Micro-organisms, bacteria, fungi, algae, protozoa or viruses, are present in our lives, some of them are fundamental for the correct function of our health, some are in our food industry and some of them are pathogenic. In the same way, polymeric materials are very familiar in our lives. Hence, join these two extent areas, this chapter intends to introduce readers to the antimicrobial polymeric materials, give a general vision about not only about the micro-organisms' world and the classification of these antimicrobial systems, but also the different approaches that are employed to fight against different diseases and the analytical procedures to know how effective is our system.
This Chapter seeks to bring the readers, in a very brief way, the wonders and the threats that microbes suppose and how human beings fight against them using polymeric materials.
1.1 Short Overview of the World of Micro-Organisms
Microbes are everywhere in the world and their presence constantly affects the environment in which they are growing. The effects of micro-organisms can be beneficial or harmful for their surroundings. Some of them can be positive, sometimes essential, in association with higher forms of organisms (e.g. bacteria and other microbes in the intestines of animals and insects digest nutrients and produce vitamins and growth factors). Moreover, microbes are also used in the manufacture of fermented foods, such as yeasts employed in the fabrication of beer, wine or breads, lactic acid bacteria used to make yogurt, cheese, and other fermented milk products. In addition, microbes are a source in medicine of antibiotics (substances produced by micro-organisms that kill or inhibit other microbes and, then, are used in the treatment of infectious diseases) and vaccines (substances derived from micro-organisms developed to immunise against diseases) for the treatment and prevention of infectious diseases. These advantages come also to biotechnological processes, playing a primary role in recombinant DNA technology and genetic engineering.
Despite these benefits, some microbes cause diseases in animals and plants (pathogens), and they are agents of spoilage and decomposition of foods, textiles and dwellings since nothing lasts forever, and the microbial decomposition of any organic substance will occur with time. Fungi and bacteria are the major microbial agents of decomposition in aerobic environments, while only bacteria can act in anaerobic media. Focusing the attention on the human population, microbial infections still cause around one quarter of all deaths worldwide, especially in undeveloped countries where there are contaminated water or food, unsanitary disposal of human waste, poor personal hygiene, inferior sanitary conditions and lack of access to medical assistance. The magnitude of these infectious diseases (e.g. cholera, dysentery, human immunodeficiency virus infection /acquired immunodeficiency syndrome, malaria, tuberculosis, etc.) is in those countries as significant as they become the first cause of mortality. On the contrary, morbidity and mortality is triggered in developed countries by the increasing incidence of antibiotic-resistant pathogens along with an easily migratory mobility that allow new paths for micro-organisms to run into human hosts to be created.1,2 Approximately 25 000 people die each year in the European Union from antibiotic-resistant bacterial infections. For example, Gram-positive Staphylococcus aureus has evolved from penicillin-resistant phenotypes into a methicillin-resistant strain (MRSA), which has become a global epidemic3,4 and it is responsible for the main surgical site infections.5,6 Countries with the highest rates of resistant infections, such as Greece, Cyprus, Italy, Hungary and Bulgaria, also tend to be the ones with the highest uses of antibiotics. One of the Global Strategy Recommendations dictated by the World Health Organization (WHO) is to make the control of antimicrobial resistance7 a priority for National Governments and Health Systems. Therefore, new prevention and control strategies are urgently required.
1.1.1 Classification of Micro-Organisms
There are five major groups of micro-organisms: bacteria, algae, fungi, protozoa, and viruses. They are divided into prokaryotic (“before nucleus”) and eukaryotic (true nucleus). The former are organisms whose cells lack a cell nucleus (karyon), or any other membrane-bound organelles (only the bacteria and the archaea); the eukaryotic micro-organisms have internal membrane-bound structures, membrane bound nucleus and membrane-bound organelles such as mitochondria, chloroplasts and the Golgi apparatus (algae, protozoa, fungi).8
In a simple way, bacteria are prokaryotic and unicellular with a size 1000 times less than the volume of a typical eukaryotic cell, exhibiting different shapes: bacillus (rod), coccus (spherical), spirillum (spiral), vibrio (curved rod). They are usually classified into two distinct types, Gram-positive and Gram-negative, that differ in the properties of their bacterial cell walls. Gram-positive bacteria are those that are stained dark blue or violet by Gram staining because of the high amount of peptidoglycan in the cell wall. On the contrary, the peptidoglycan layer is thinner in Gram-negative bacteria and is protected by an outer membrane. Consequently, they cannot retain the crystal violet stain, turning in this case reddish or pink by counter-stain (safranin, fuchsine or other stains). In general, Gram-negative bacteria are more resistant against antibiotics compared with Gram-positive ones, because of their outer membrane.
Algae are eukaryotic and unicellular or multicellular; fungi are eukaryotic and unicellular (yeasts) or multicellular (moulds); protozoa (first animals) are eukaryotic and unicellular and viruses are acellular and, then, they are forced to live as intracellular parasites.9
1.1.2 Methods of Measuring Microbial Growth
It is of great importance to know the population of micro-organisms and the rates of their growth to inhibit or prevent microbes proliferation. There are numerous techniques of counting microbial growth,10 measuring either cell mass or cell number, the following are examples:
(a) Dry/wet weight measurement:
This method is a direct approach to determine the net weight of cells. A known volume of culture sample is centrifuged to sediment micro-organisms to the bottom of a vessel. The sedimented cells (called a cell pellet) are, then, washed and weighted in case of wet measurements. Dry weight is measured after drying the centrifuged cells. Dry weight is usually about 10–20% of the wet weight, and gives more consistent results and normally is taken as the reference method. These techniques are simple but highly time consuming. In addition, they are not very sensitive and also cannot distinguish between live and dead bacteria.
(b) Absorbance/turbidity:
Absorbance is measured by using a spectrophotometer. Light scattering rises with the increase in cell number. When light is passed through bacterial cell suspension, light is scattered by the cells and transmission decays. At a particular wavelength, light absorbance is proportional to the cell concentration of micro-organisms present in the suspension. This is a nondestructive method that is also very simple, rapid and accurate. Both live and dead cells are, however, able to scatter light and, therefore, both are counted.
(c) Total cell count:
Cell growth is also measured by counting the total cell number of the microbes present in the sample. Total cells (both live and dead) are microscopically counted by using special microscope glass slide or counting chamber, such as, Helber or Petroff–Hausser slides. Typically, this chamber consists of a slide with a grid with etched squares of known area. For example, the surface of the platform is etched with a grid system in the case of Petroff-Hausser chamber. This consists of 25 large squares, each of which is divided into 16 smaller squares. Cells are then counted (normally more than 500) with a phase contrast microscope using a sufficient and appropriate numbers of squares. The number of cells per mL of sample is subsequently calculated from the average cell number per square divided by the volume of a single square. The dilution factors should be taken into account. The main disadvantages of this method are that a high concentration of bacteria is required and the complexity to distinguish between living or dead cells. On the other hand, this is a simple method and does not need any incubation time.
(d) Viable count:
A viable cell is defined as a cell that is able to divide and increase cell numbers. The normal way to perform a viable count is to determine the number of cells in the sample that are capable of forming colonies on a suitable medium. It is assumed that each viable cell will form one colony. Therefore, the viable count is often called the plate count or colony count. This method requires an incubation period of ca. 24 h or longer and can be done in selective and differential. There are two ways of forming plate count: (i) Spread count method: a volume of culture is spread over the surface of an agar plate by using a sterile glass spreader. The plate is incubated to develop colonies. Then, the number of colonies is counted. (ii) Pour plate method: a known volume of the culture is added into sterile Petri dishes. Subsequently, the melted agar medium is poured and gently mixed and, next, incubated. After that, the colonies growing on the surface of the agar are counted. The major shortcoming of this method is the assumption that each colony is generated from a single bacterial cell, thus, sometimes it entails underestimation of the true population. Besides, this technique is time consuming and labour intensive. Despite its disadvantages, the viable plate count is the most frequently used method for measuring cell number because it is very sensitive and allows counting only living bacteria.
(e) Cell-counting instruments:
Coulter counters and flow cytometers are extensively used to count total cells in dilute solutions. Coulter counters are based on electrical impedance. That is, the cells contained in the liquid cause a variation in the electrical impedance that is proportional to the size of the particle. Consequently, the size and the number of cells within a solution can be determined. Flow cytometry is a powerful technique for cell counting that simultaneously measures and, then, analyses physical properties of the cells, such as the light scattering or fluorescence. In this technique, cells are carried in a fluid stream to a laser intercept, thus, thousands of cells pass through a laser beam and the light that emerges from each cell is collected and examined. Flow cytometry can also be used to count organisms to which fluorescent dyes or tags have been attached.
Moreover, there are other methods among all of these common measurements, such as: determination of the amount of a given element, usually nitrogen; acid titration with a pH indicator to quantify acid production; the carbon dioxide formation by using a molecule that fluoresces when the medium becomes slightly more acidic (this gas can be trapped in an inverted Durham tube in a tube of broth); and also ATP measurement using firefly luciferase catalyses light-emitting reaction. However, these methods are more tedious and not often used.
1.1.3 Mechanisms of Action against Micro-Organisms
There are different modes of action against micro-organisms: 1) by affecting their proteins, i.e. denaturation or alteration of their protein structure. This denaturation can be either permanent and, then, the action mechanism is called bactericidal, fungicidal, etc., or temporary if their initial and standard structure can be restored, being then called bacteriostatic, fungistatic, etc. The common mechanisms of denaturation include disruption of hydrogen and disulfide bonds. Another mechanism is 2) by affecting their cell membrane proteins or membrane lipids. Concerning proteins, the mode of action consists of denaturalisation whereas lipids are dissolved, for instance by a surfactant, and their cell membrane turns out to be damaged. Others mechanisms are 3) by affecting the cell-wall formation through blocking its synthesis; 4) by preventing replication, transcription and translation of the nucleic acid structure or 5) by disturbing the metabolism.
1.2 Antimicrobial Polymeric Materials
1.2.1 Brief Introduction
World Health Organization (WHO) has elaborated a catalogue collecting the major concerns about health. The list is the following:
Alcohol and health.
Avian influenza A (H5N1).
Child and adolescent health and development.
Cholera.
Environmental and health (household air pollution, outdoor air pollution).
Expenditures on health (investment on health and on research).
HIV/AIDS.
Integrated management of childhood illness (IMCI).
Influenza.
Malaria.
Maternal and reproductive health.
Meningococcal disease.
Mortality and burden of disease.
Neglected tropical disease.
Noncommunicable diseases (cardiovascular diseases, cancer, diabetes and chronic respiratory diseases).
Pandemic (H1N1) 2009.
Poliomyelitis.
Substance use and substance abuse.
Tobacco.
Tuberculosis.
Violence and injuries.
Water, sanitation and health.
As can be noticed, many of them are caused by micro-organisms. For example, influenza is a virus and the main strategy to prevent this illness is the vaccination treatment. Cholera is an infection in the small intestine caused by the bacterium Vibrio cholerae. The main symptoms are profuse, watery diarrhoea and vomiting. Transmission occurs primarily by drinking water or eating food that has been contaminated by the faeces of an infected person, including one with no apparent symptoms. In this sense, inadequate access to safe water and sanitation services as well as poor hygiene practices, kills and sickens thousands of children every day, and leads to impoverishment and diminished opportunities for thousands more.11 Various factors lead to water deterioration, including population growth, rapid urbanisation, agricultural land uses, industrial discharge of chemicals, etc. During recent years, it has been shown that the pharmaceuticals are only partially removed in wastewater treatment plants and have been detected in water bodies.1,12,13 Hospitals contribute in a large extent to the load of wastewater treatment plants, they should be taking into consideration for point-source measures, such as implementing methods to decrease pharmaceuticals or introducing single-use pocket urinals to remove X-ray contrast agents (90–94% are excreted with the urine). In this sense and very recently, Kovalova et al.14 described a pilot-scale membrane bioreactor operating during one year at a Swiss hospital where 68 target analytes (56 pharmaceuticals, such as antibiotics, antimycotics, antivirals, iodinated X-ray contrast media, anti-inflammatory, cytostatics, etc., 10 metabolites, and 2 corrosion inhibitors) were studied. They make an improvement in the pollutant elimination, almost 90%, when only pharmaceuticals and metabolites are considered without iodinated X-ray contrast media.
Therefore, the cleaning, disinfection and sterilisation of wastewater and/or air is an important target in the antimicrobial policy. However, the contaminants are not only concentrated at outdoor sources; there are also chemical contaminants from indoor supplies. Legionella bacteria and Legionella pneumophila causes legionellosis, a collection of infections that emerged in the second half of the 20th century, and cause a high level of morbidity and mortality in the people exposed.15 These micro-organisms can be raised in stationary places due to inadequate ventilation, from stationary water, principally in humidifiers or cooling towels, spa pools, spread from air vent systems and/or from water that has been collected on carpets or wood furniture.
Although most of the infectious diseases, such as malaria, meningitis, poliomyelitis, among others, are most frequently given in undeveloped countries, the sexual diseases, such as chlamydia, gonorrhoea, genital herpes, HIV/AIDS, human papilloma viruses (HPV), hepatitis, syphilis or trichomoniasis, are of great concern even in technologically advanced countries because these infections are present all over the world. Moreover, fungal keratitis is a leading cause of ocular morbidity throughout the world, and it is also a major eye disease that leads to blindness in Asia.16,17 In relation to common problems of human beings, bad odour is one of the most recurrent struggles and it is produced by different bacteria when they digest sugars. Bacillus subtilis and Staphylococcus epidermidis, contribute to foot odour and the latter is also responsible along with Corynebacterium xerosis for underarm odour.18,19
All these facts indicate the importance of investing not only in prevention but also in new formulations to combat the micro-organisms. At this point, polymeric materials come into play within the game of antimicrobial systems. In general, the antibiotics, antifungals or antivirals are based on natural products or low molecular weight components, but they have the problem of residual toxicity, even when suitable amounts of the agents are added.20,21 The use of antimicrobial polymeric materials offers a guarantee for enhancing the efficacy of some existing antimicrobial agents and for minimising, at the same time, the environmental problems that escort conventional antimicrobial agents by reducing their residual toxicity, increasing their efficiency and selectivity, and prolonging their lifetime. In addition, these antimicrobial polymeric materials are nonvolatile and chemically stable.22 This fact is essential for developing antimicrobial systems that are not easily susceptible to resistance.23 It is important to remark that the effectiveness of an antimicrobial agent is affected by time, temperature, pH, and concentration, among other factors.
1.2.2 Classification of Antimicrobial Polymeric Materials
Antimicrobial polymers involved traditionally covalent linkages of groups with antimicrobial activity. The synthesis of antimicrobial polymers and copolymers based on 2-methacryloxytroponones was described for the first time by Cornell and Dunaruma24 in 1965. Many of these polymers showed a good and broad spectrum of antibacterial activity. The group of Dunaruma25–29 worked very actively on the synthesis of new polymers with antimicrobial activity, such as sulfonamide-dimethylolurea copolymers, N-acylsulfanilamide, sulfonamide or sulfapyridine-formaldehyde copolymers. Ascoli et al.30 also developed a polymeric nitrofuran derivative with extended antibacterial action. Later, Ackart et al.31 described a series of carboxyl-containing ethylene copolymers that exhibited long term antibacterial and antifungal properties. These authors tried to blend these polymers with commodity polymers and made water emulsions to test their applicability as components of protecting coatings. Panarin et al.32 synthesised copolymers with N-vinylpyrrolidone with (2-methacryloxyethyl)triethylammonium iodine or bromide and studied the influence of these macromolecules, their size and the amount of quaternary ammonium groups on the antimicrobial activity. Vogl and Tirrell33 demonstrated that nondegradable polymers with functional groups, i.e. polymers and copolymers of 4-vinylsalicylic acid and 5-vinylsalicylic acid derivatives were very active against Gram-positive and/or Gram-negative bacteria. The activity of poly(4-vinylsalicylic acid) and poly(5-vinyl-salicylic acid) was found to be independent of molecular weight. In addition, selective activity was obtained by preparing copolymers of 4-vinylsalicylic acid or 5-vinylsalicylic acid with methacrylic acid, a comonomer whose homopolymer is inactive.
A large number of antimicrobial polymers have appeared since those days. Recently, several reviews have summarised the state-of-the-art.22,34–40 Different parameters are discussed, such as molecular weight, type and degree of alkylation, distribution of charge, hydrophobic/hydrophilic ratio and their influence on the activity, and the action mode of antimicrobial polymeric materials is evaluated. Although there are several ways to classify these systems, we have arranged them in this book into four categories38 (see Figure 1.1): a) polymers with antimicrobial activity; b) polymers that undergo chemical modifications to achieve antimicrobial activity; c) polymers containing antimicrobial organic compounds and; d) polymers incorporating antimicrobial inorganic compounds.
Representation of (a) polymers with antimicrobial activity; (b) chemical modification of polymers to achieve antimicrobial properties; (c) incorporation of antimicrobial organic compounds (either of low or high molecular weight) with antimicrobial activity into polymers and; (d) introduction of antimicrobial inorganic materials to polymers to achieve antimicrobial activity.
Representation of (a) polymers with antimicrobial activity; (b) chemical modification of polymers to achieve antimicrobial properties; (c) incorporation of antimicrobial organic compounds (either of low or high molecular weight) with antimicrobial activity into polymers and; (d) introduction of antimicrobial inorganic materials to polymers to achieve antimicrobial activity.
(a) Polymers with antimicrobial activity. As their name indicates they display antimicrobial activity by themselves. Usually, their chemical structure is used as the key characteristic to make the categories. Therefore, polymers can be found with quaternary nitrogen atoms (acrylic and methacrylic polymers, cationic conjugated polyelectrolytes, polysiloxanes, polyoxazolines, polyionenes, etc.), guanidine-containing polymers, polymers mimicking natural peptides (synthetic peptides, arylamide and phenylene ethynylene backbone polymers, halogen polymers, polynorbornene derivatives), halogen polymers (fluorine or chlorine-containing polymers, polymeric N-halamines), polymers containing phospho- and sulfo-derivatives, phenol and benzoic acid derivative polymers, organometallic polymers and others.
(b) Polymers that undergo chemical modifications to achieve antimicrobial activity. There are different approaches to incorporate antimicrobial activity into polymers. In particular, several scenarios can be distinguished if chemical modification is involved: i) a small molecule with antimicrobial activity is covalently attached to the polymer; (ii) antimicrobial peptides are fixed on an inactive polymer and (iii) antimicrobial polymers are grafted to regular polymers. In all these cases, it is desirable that chemical modification does not cause a deterioration of the properties of the final polymeric material.
(c) Polymers containing antimicrobial organic compounds. In this case, the antimicrobial activity is due to (i) noncovalent links between antimicrobial agents, either natural or synthetic, and polymers with the corresponding compound release and (ii) the mixture/blend of antimicrobial polymers and nonactive polymers to confer their biocide characteristics.
(d) Polymers incorporating antimicrobial inorganic compounds. In this category, the antimicrobial activity in the final material is obtained by transfer of the biocidal action of inorganic systems, such as metals, metallic oxides or modified clays, into the polymers.
As we will notice in subsequent chapters the present classification is only performed from a chemical point of view. If we focus our attention on the final applications, we realise that this division shows weak points, since one system depending on its characteristics can be applied for several purposes or functions. Anyway, we would like to give to the reader an extensive picture on how these polymeric materials can be synthesised and their potential applications.
1.2.3 Methods for Determining In Vitro Antimicrobial Activity
The increasing resistance to antibiotics and the appearance of new antimicrobial systems make necessary the establishment of methods that can assess the antimicrobial activity of these agents. The killing effect of an antimicrobial agent on a micro-organism can be measured by different approaches. Antimicrobial susceptibility tests (AST) are routinely used in clinical microbiology laboratories to evaluate the microbial pathogens susceptibility or detect resistance to antimicrobial agents. ATS methods commonly include diffusion (disk and E test diffusion) and dilution (agar dilution and broth microdilution) methodologies that measure the inhibitory activity of the tested agent. Other different methods that are not routinely applied to all micro-organisms but very advantageous in some situations, such as time-kill kinetic studies, MBC determination, serum bactericidal test41 are now described:
(a) Disk diffusion method. This is commonly referred to as the Kirby–Bauer test and gives a quantitative measure of the effect of an antimicrobial agent against bacteria grown in culture. In this test, a 6-mm filter paper disks impregnated with a known amount of antimicrobial agent is placed onto an agar plate and water from the agar is absorbed into the disk. Then, the antimicrobial agent starts to diffuse into the surrounding agar. The plates are incubated overnight, and the inhibition zone of bacterial growth is used as a measure of susceptibility. If the organism is accessible to a specific antimicrobial agent, there will be no growth around the disc containing the antibiotic. Thus, large zones of inhibition indicate that the organism is susceptible, while a small or absent zone of inhibition indicates resistance. This method is simple, economical and there are several commercially available disks. However, not all organisms can be accurately tested, especially slow growing organisms.
(b) Epsilometer test, E test. This is a well-established commercially available method to directly quantify the susceptibility in terms of minimal inhibitory concentration (MIC). The procedure is briefly as follows: bacteria are grown on an agar plate and the E test plastic strip is placed on the top. Subsequently, the antimicrobial agent starts to diffuse into the agar and an exponential gradient of antimicrobial concentration is generated. After the incubation, the MIC can be directly read from the test strip according to the instructions of the manufacturer, where the elliptical zone of inhibition intersects with the MIC scale on the strip.
(c) Broth dilution test. This is one of the earliest antimicrobial susceptibility testing methods. This procedure involves the preparation of serial dilutions of the antimicrobial agents that are inoculated with a standardised number of micro-organisms in tubes and incubated overnight. The tubes are examined for visible bacterial growth by turbidity. The lowest concentration of antimicrobial agent that prevents the appearance of turbidity is considered the MIC. In addition to the determination of the MIC, the minimal bactericidal concentration (MBC) can also be estimated. Its main disadvantage consists in that this method is very tedious and laborious.
(d) Time-kill-kinetic assay. The lethal activity can be expressed as the rate of killing at a given concentration of antimicrobial under controlled conditions. This rate is determined by measuring the number of viable micro-organisms at various time intervals. The resulting graphic representation is known as the time-kill curve. Micro-organism killing rates are, in some way, dependent on the class of antimicrobial system and the concentration of it. The rate of killing rises for certain classes of antimicrobial systems with increasing antimicrobial concentrations up to a point of maximum effect. This is termed concentration-dependent bactericidal activity. In contrast, the killing rates of other antimicrobial agents are relatively slow and continue only as long as the concentrations are in excess of the minimal inhibitory concentration, that is, the lowest concentration of antimicrobial agent that inhibits the growth of the micro-organism. This rate of killing is termed the time-dependent bactericidal activity. There is also a third category, consisting of antibiotics with both time-dependent and concentration-dependent effects.42
(e) MBC determination. The minimal concentration of antimicrobial needed to kill most (≥ 99.9%) of the viable organisms after incubation for a fixed period of time (generally 24 h) under a given set of conditions. It is the most common estimation of bactericidal activity and is known as either the minimal bactericidal concentration (MBC), minimal fungicidal concentration (MFC) or the minimal lethal concentration (MLC). The definition of the MBC (99.9% killing of the final inoculums, which is the growth method or direct suspension equivalent to 0.5 McFarland standard) is somewhat arbitrary and its determination is, moreover, subject to methodological variables. MBC determination is mainly indicated in some cases of endocarditis, osteomyelitis, meningitis, and sepsis in neutropenic patients, since they consist of serious infections in immune-compromised patients requiring antibiotic levels lethal to the infecting organism, or infections located in a site that is difficult to reach with antibiotics.
(f) Serum bactericidal test. The serum of a patient receiving an antimicrobial agent may be tested against the infecting micro-organism. This can be done using time-kill curve methodology (i.e. serum bactericidal rate, SBR) or using dilution methodology (i.e. serum bactericidal titer, SBT). The principles of these methods and the influence of biological and technical factors are similar.
Tables 1.1–1.4 collect the common micro-organisms tested for analysing the antimicrobial polymer capacity. Micro-organisms can be easily located from these tables, where it can be seen if they are pathogenic or not for humans, the disease that they can cause and where they can be usually found.
Features of different Gram-positive and Gram-negative bacteria.
| Group | Micro-Organisms | Pathogenic Disease | Source |
|---|---|---|---|
| Gram-negative bacteria | Bacteroides forsythus | Periodontal diseases | Oral cavity |
| Cellulophaga lytica | Nonpathogenic | Marine environment | |
| Chlamydia pneumonia | Respiratory illness | Respiratory secretions | |
| Chlamydia trachomatis | Urethritis, proctitis, trachoma and infertility | Eyes infection, also in genital tract, rectum | |
| Escherichia coli | Harmless, some serotypes cause food poisoning | Contaminated food | |
| Haemophilus influenza | Bacterial meningitis, upper respiratory tract infections, pneumonia, bronchitis | Upper respiratory system | |
| Klebsiella pneumoniae | Pneumonia and other respiratory inflammations | Respiratory infections | |
| Mycoplasma gallisepticum | Nonpathogenic, chronic respiratory diseases in birds | Chickens, turkeys, birds | |
| Neisseria gonorrhoeae | Gonorrhoea, ophthalmia neonatorum, septic arthritis | Sexually transmitted infection | |
| Porphyromonas gingivalis | Periodontal diseases | Oral cavity | |
| Proteus mirabilis | Urinary tract infections and the formation of stones | Human gastrointestinal tract and also in free living in water and soil | |
| Proteus vulgaris | Urinary tract infections and wound infections | Intestinal tracts of humans and animals and also in soil, water and faecal matter | |
| Pseudomonas aeruginosa | Inflammation and sepsis. Bacteraemia, infections of eye, ear skin, urinary, bone, respiratory system, gastrointestinal tract, nervous system. Secondary pneumonia and endocarditis | Soil, water, skin flora, in medical equipment | |
| Pseudomonas fluorescens | Nonpathogenic | Soil and water | |
| Pseudomonas putida | Nonpathogenic | Soil | |
| Pseudoalteromonas haloplanktis | Intoxication by production of tetraodontoxin | Marine environment | |
| Salmonella enteritidis | Fever, abdominal cramps, and diarrhoea | Food-borne eggs | |
| Salmonella typhi | Typhoid fever, Dysentery, Colitis | Food-borne faecal contaminated, food or drinking water | |
| Salmonella typhimurium | Salmonellosis with gastroenteritis and enterocolitis | Intestinal lumen | |
| Serratia liquefaciens | Urinary tract infections, bloodstream infections, sepsis, pneumonia, meningocephalitis | Soil, water, plants, and the digestive tracts of rodents, insects, fishes, and humans | |
| Shigella boydii | Diarrhoea and shigellosis | Intestine and rectum of humans and other primates. Faeces and soil and/or food/water contaminated with faecal matter | |
| Shigella dysenteriae | Dysentery | Faecal-oral contamination and in contaminated food and water | |
| Shigella sonnei | Shigellosis in general | Faecal-oral contamination and in contaminated food and water | |
| Spiroplasma citri | Nonpathogenic | Citrus trees | |
| Spiroplasma floricola | Nonpathogenic | Flowers of tulip tree | |
| Spiroplasma melliferum | Nonpathogenic | Honeybees | |
| Stenotrophomonas maltophilia | Bacteraemia, pneumonia, urinary tract infection | Aqueous environments, soil and plants. Breathing tubes, and indwelling urinary catheters | |
| Yersinia enterocolitica | Gastric infections, diarrhoea | Food-borne route | |
| Yersinia pseudotuberculosis | Tuberculosis-like symptoms | Food-borne pathogen, intestinal tract, liver, spleen, and lymph nodes | |
| Gram-positive bacteria | Acholeplasma laidlawii | Nonpathogenic | Animals, and some plants and insects |
| Actinomyces viscosus | Periodontal disease in dogs and cattle. Human dental calculus and root surface caries | Oral cavity of dogs and humans | |
| Bacillus coagulans | Nonpathogenic (beneficial bacteria) | Food products | |
| Bacillus cereus | Severe nausea, vomiting and diarrhoea | Foodborne pathogen (when food is improperly refrigerated) | |
| Bacillus megaterium | Nonpathogenic | Soil | |
| Bacillus subtilis | Nonpathogenic for humans | Soil and vegetation | |
| Bacillus thuringiensis | Nonpathogenic for humans | Soil | |
| Bifidobacterium bifidum | Nonpathogenic | Digestive system, mouth, breast milk and the vagina | |
| Bifidobacterium breve | Nonpathogenic | Lower digestive tract of the human body | |
| Broehothrix thermosphacta | Nonpathogenic | Chilled raw meats and processed meat products stored aerobically or under modified atmospheres | |
| Clostridium difficile | Colitis, inflammation and mucosal injury to the colon | Faeces, Foodborne | |
| Enterococcus faecalis | Lower urinary tract infections (cystitis, prostatitis, and epididymitis) as well as intra-abdominal, pelvic, and soft tissue infections. Less common infections include meningitis, haematogenous, osteomyelitis, septic arthritis, and pneumonia | Nosocomial environments/long-term care | |
| Enterococcus faecium | Bacteraemia, surgical wound infection, endocarditis, and urinary tract infections | Nosocomial environments | |
| Enterococcus hirae | Pathogenic mainly in animals and very rare in human (septicaemia, endocarditis) | Intestinal flora of domestic animals, foods of animal origin and water | |
| Lactobacillus casei | Nonpathogenic | Fermentation processes (cheese, yogurt, fermented milks, fermented Sicilian green olives, and other products) | |
| Lactobacillus salivarius | Nonpathogenic | Oral cavities, intestines, and vagina | |
| Listeria monocytogenes | Listeriosis. Noninvasive: gastroenteritis. Invasive: septicaemia and meningitis | Foodborne pathogen | |
| Micrococcus luteus | Pruritic eruptions and severe itching. In immuno-compromised patients: septic shock, pneumonia endocarditis or sepsis | Soil, dust, water and air, and as part of the skin flora of mammal | |
| Mycobacterium smegmatis | Nonpathogenic | Soil, water, and plants | |
| Mycobacterium tuberculosis | Tuberculosis | Mammalian respiratory system | |
| Pediococcus pentosaceus | Nonpathogenic | Plant, ripened cheese, and a variety of processed meats | |
| Staphylococcus aureus (methicillin-resistant Staphylococcus aureus, MSRA) | Mild skin infections (impetigo, folliculitis, etc.), invasive diseases (wound infections, osteomyelitis, bacteremia, etc.), toxin mediated diseases (food poisoning, toxic shock syndrome, scaled skin syndrome, etc.) and pneumonia. | Contaminated food and nosocomial environments | |
| Staphylococcus epidermidis | Inflammation and pus secretion, endocarditis, sepsis | Nosocomial infections (sutures, indwelling catheters, and implanted joints) | |
| Staphylococcus haemolyticus | Septicaemia, peritonitis, infections of urinary tract, wound, bone and joints | Skin flora of humans, in axillae, perineum, and inguinal areas. Nosocomial infections due to insertion of foreign bodies, such as prosthetic valves | |
| Staphylococcus hominis | Bacteraemia | Human skin especially common in the axillae and the pubic area, where apocrine glands are numerous. Nosocomial infections | |
| Staphylococcus saprophyticus | Urinary tract infections | Gastrointestinal tracts, meat, cheese and vegetable products | |
| Streptococcus mutans | Dental caries under frequent and prolonged acidic conditions. | Oral cavity | |
| Streptococcus pneumoniae | Pneumonia, acute sinusitis, otitis media, meningitis, bacteraemia, sepsis, osteomyelitis, septic arthritis, endocarditis, peritonitis, pericarditis, cellulitis, and brain abscess | Respiratory tracts of mammals | |
| Streptococcus pyogenes | Pharyngitis, tonsillitis, sinusitis, otitis, pneumonia, impetigo, erysipelas, cellulitis, joint or bone infections, necrotising fasciitis, myositis, meningitis, endocarditis, scarlet fever, rheumatic fever and glomerulonephritis | Respiratory specimens, skin lesions, blood, sputum and wound |
| Group | Micro-Organisms | Pathogenic Disease | Source |
|---|---|---|---|
| Gram-negative bacteria | Bacteroides forsythus | Periodontal diseases | Oral cavity |
| Cellulophaga lytica | Nonpathogenic | Marine environment | |
| Chlamydia pneumonia | Respiratory illness | Respiratory secretions | |
| Chlamydia trachomatis | Urethritis, proctitis, trachoma and infertility | Eyes infection, also in genital tract, rectum | |
| Escherichia coli | Harmless, some serotypes cause food poisoning | Contaminated food | |
| Haemophilus influenza | Bacterial meningitis, upper respiratory tract infections, pneumonia, bronchitis | Upper respiratory system | |
| Klebsiella pneumoniae | Pneumonia and other respiratory inflammations | Respiratory infections | |
| Mycoplasma gallisepticum | Nonpathogenic, chronic respiratory diseases in birds | Chickens, turkeys, birds | |
| Neisseria gonorrhoeae | Gonorrhoea, ophthalmia neonatorum, septic arthritis | Sexually transmitted infection | |
| Porphyromonas gingivalis | Periodontal diseases | Oral cavity | |
| Proteus mirabilis | Urinary tract infections and the formation of stones | Human gastrointestinal tract and also in free living in water and soil | |
| Proteus vulgaris | Urinary tract infections and wound infections | Intestinal tracts of humans and animals and also in soil, water and faecal matter | |
| Pseudomonas aeruginosa | Inflammation and sepsis. Bacteraemia, infections of eye, ear skin, urinary, bone, respiratory system, gastrointestinal tract, nervous system. Secondary pneumonia and endocarditis | Soil, water, skin flora, in medical equipment | |
| Pseudomonas fluorescens | Nonpathogenic | Soil and water | |
| Pseudomonas putida | Nonpathogenic | Soil | |
| Pseudoalteromonas haloplanktis | Intoxication by production of tetraodontoxin | Marine environment | |
| Salmonella enteritidis | Fever, abdominal cramps, and diarrhoea | Food-borne eggs | |
| Salmonella typhi | Typhoid fever, Dysentery, Colitis | Food-borne faecal contaminated, food or drinking water | |
| Salmonella typhimurium | Salmonellosis with gastroenteritis and enterocolitis | Intestinal lumen | |
| Serratia liquefaciens | Urinary tract infections, bloodstream infections, sepsis, pneumonia, meningocephalitis | Soil, water, plants, and the digestive tracts of rodents, insects, fishes, and humans | |
| Shigella boydii | Diarrhoea and shigellosis | Intestine and rectum of humans and other primates. Faeces and soil and/or food/water contaminated with faecal matter | |
| Shigella dysenteriae | Dysentery | Faecal-oral contamination and in contaminated food and water | |
| Shigella sonnei | Shigellosis in general | Faecal-oral contamination and in contaminated food and water | |
| Spiroplasma citri | Nonpathogenic | Citrus trees | |
| Spiroplasma floricola | Nonpathogenic | Flowers of tulip tree | |
| Spiroplasma melliferum | Nonpathogenic | Honeybees | |
| Stenotrophomonas maltophilia | Bacteraemia, pneumonia, urinary tract infection | Aqueous environments, soil and plants. Breathing tubes, and indwelling urinary catheters | |
| Yersinia enterocolitica | Gastric infections, diarrhoea | Food-borne route | |
| Yersinia pseudotuberculosis | Tuberculosis-like symptoms | Food-borne pathogen, intestinal tract, liver, spleen, and lymph nodes | |
| Gram-positive bacteria | Acholeplasma laidlawii | Nonpathogenic | Animals, and some plants and insects |
| Actinomyces viscosus | Periodontal disease in dogs and cattle. Human dental calculus and root surface caries | Oral cavity of dogs and humans | |
| Bacillus coagulans | Nonpathogenic (beneficial bacteria) | Food products | |
| Bacillus cereus | Severe nausea, vomiting and diarrhoea | Foodborne pathogen (when food is improperly refrigerated) | |
| Bacillus megaterium | Nonpathogenic | Soil | |
| Bacillus subtilis | Nonpathogenic for humans | Soil and vegetation | |
| Bacillus thuringiensis | Nonpathogenic for humans | Soil | |
| Bifidobacterium bifidum | Nonpathogenic | Digestive system, mouth, breast milk and the vagina | |
| Bifidobacterium breve | Nonpathogenic | Lower digestive tract of the human body | |
| Broehothrix thermosphacta | Nonpathogenic | Chilled raw meats and processed meat products stored aerobically or under modified atmospheres | |
| Clostridium difficile | Colitis, inflammation and mucosal injury to the colon | Faeces, Foodborne | |
| Enterococcus faecalis | Lower urinary tract infections (cystitis, prostatitis, and epididymitis) as well as intra-abdominal, pelvic, and soft tissue infections. Less common infections include meningitis, haematogenous, osteomyelitis, septic arthritis, and pneumonia | Nosocomial environments/long-term care | |
| Enterococcus faecium | Bacteraemia, surgical wound infection, endocarditis, and urinary tract infections | Nosocomial environments | |
| Enterococcus hirae | Pathogenic mainly in animals and very rare in human (septicaemia, endocarditis) | Intestinal flora of domestic animals, foods of animal origin and water | |
| Lactobacillus casei | Nonpathogenic | Fermentation processes (cheese, yogurt, fermented milks, fermented Sicilian green olives, and other products) | |
| Lactobacillus salivarius | Nonpathogenic | Oral cavities, intestines, and vagina | |
| Listeria monocytogenes | Listeriosis. Noninvasive: gastroenteritis. Invasive: septicaemia and meningitis | Foodborne pathogen | |
| Micrococcus luteus | Pruritic eruptions and severe itching. In immuno-compromised patients: septic shock, pneumonia endocarditis or sepsis | Soil, dust, water and air, and as part of the skin flora of mammal | |
| Mycobacterium smegmatis | Nonpathogenic | Soil, water, and plants | |
| Mycobacterium tuberculosis | Tuberculosis | Mammalian respiratory system | |
| Pediococcus pentosaceus | Nonpathogenic | Plant, ripened cheese, and a variety of processed meats | |
| Staphylococcus aureus (methicillin-resistant Staphylococcus aureus, MSRA) | Mild skin infections (impetigo, folliculitis, etc.), invasive diseases (wound infections, osteomyelitis, bacteremia, etc.), toxin mediated diseases (food poisoning, toxic shock syndrome, scaled skin syndrome, etc.) and pneumonia. | Contaminated food and nosocomial environments | |
| Staphylococcus epidermidis | Inflammation and pus secretion, endocarditis, sepsis | Nosocomial infections (sutures, indwelling catheters, and implanted joints) | |
| Staphylococcus haemolyticus | Septicaemia, peritonitis, infections of urinary tract, wound, bone and joints | Skin flora of humans, in axillae, perineum, and inguinal areas. Nosocomial infections due to insertion of foreign bodies, such as prosthetic valves | |
| Staphylococcus hominis | Bacteraemia | Human skin especially common in the axillae and the pubic area, where apocrine glands are numerous. Nosocomial infections | |
| Staphylococcus saprophyticus | Urinary tract infections | Gastrointestinal tracts, meat, cheese and vegetable products | |
| Streptococcus mutans | Dental caries under frequent and prolonged acidic conditions. | Oral cavity | |
| Streptococcus pneumoniae | Pneumonia, acute sinusitis, otitis media, meningitis, bacteraemia, sepsis, osteomyelitis, septic arthritis, endocarditis, peritonitis, pericarditis, cellulitis, and brain abscess | Respiratory tracts of mammals | |
| Streptococcus pyogenes | Pharyngitis, tonsillitis, sinusitis, otitis, pneumonia, impetigo, erysipelas, cellulitis, joint or bone infections, necrotising fasciitis, myositis, meningitis, endocarditis, scarlet fever, rheumatic fever and glomerulonephritis | Respiratory specimens, skin lesions, blood, sputum and wound |
Features of different fungi, differentiating yeasts.
| Group | Micro-Organisms | Pathogenic disease | Source |
|---|---|---|---|
| Fungi | Alternaria alternate | Upper respiratory tract infections and asthma | Leaves of trees |
| Aspergillus flavus | Hepatitis, immunosuppression, hepatocellular carcinoma, and neutropenia | Cereal grains and legumes | |
| Aspergillus fumigatus | Pulmonary infections | Soil and decaying organic matter | |
| Aspergillus niger | Lung diseases | Certain fruits and vegetables | |
| Aspergillus terreus | Rare, only in people with deficient immune systems pulmonary diseases | In tropical and subtropical areas. It is common in stored crops | |
| Byssochlamys fulva | Nonpathogenic | Acidic canned fruits | |
| Botrytis cinerea | “Winegrower's lung”, a rare form of hypersensitivity pneumonitis | Many plant species, such as wine grapes | |
| Chaetosphaeridium globosum | Nonpathogenic | Fresh water | |
| Cladosporium cladosporioides | Very rare, agents of phaeohyphomycosis | Herbaceous and woody plants and dead organic matter | |
| Eurotium tonophilum (Aspergillus tonophilus) | Nonpathogenic | Soybeans, rice | |
| Fusarium moniliforme | Nonpathogenic | Rice, sugarcane and maize | |
| Fusarium oxysporum | Rare, some cases of fungal keratitis, Onychomycosis, hyalohyphomycosis | Banana trees and many plants | |
| Microsporum gypseum | Tinea capitis, tinea corpus, ringworm, and other skin and hair diseases | Warm humid weather | |
| Mucor circinelloides | Mucormycosis | Plants | |
| Penicillium citrinum | Nonpathogenic | Cereal plants | |
| Penicillium digitatum | Nonpathogenic | Citrus fruits | |
| Penicillium funiculosum | Nonpathogenic | Tropical areas: water, soil, food products, etc. | |
| Penicillium pinophilum | Nonpathogenic | Tomato and cotton plants | |
| Pyrobaculum islandicum | Nonpathogenic | Submarine hydrothermal systems | |
| Rhizoctonia bataticola | Rare cases of cutaneous and renal infections | Many plants such as soybean, peanut, and corn | |
| Rhizopus oryzae | Mucormycosis | Dead organic matter | |
| Rhizopus stolonifer | Nonpathogenic | Bread, soft fruits such as bananas and grapes, etc. | |
| Sporotrichum pulverulentum | Nonpathogenic | Plants | |
| Stachybotrys chartarum | Chronic fatigue, fever, irritation to the eyes, nausea, vomiting, pulmonary haemorrhage | Building materials rich in cellulose when they are wet | |
| Trichoderma lignorum | Nonpathogenic | Soil | |
| Trichophyton rubrum | Tinea pedis (athlete's foot), tinea cruris, ringworm | Environmental heat and humidity: swimming pools, tight shoes | |
| Trichophyton mentagrophytes | Cutaneous infections | Soil, floor of swimming pools, animals, footwear | |
| Trichoderma virens | Nonpathogenic | Soil | |
| Trichoderma viridis | Nonpathogenic | Soil | |
| Yeasts | Aureobasidium pullulans | Dyspnea, cough, fever, chest infiltrates, acute inflammatory reaction and hypersensitivity pneumonitis | In different environments (e.g. soil, water, air and limestone) |
| Candida albicans | Infections in the skin, mucouses and visceras, causing mild inflammation. Also vaginal thrush | Saprophyte of the human and animal digestive tract | |
| Candida glabrata | Infections of the urogenital tract and bloodstream | Normal flora of healthy individuals and also nosocomial environments | |
| Candida parapsilosis | Sepsis and of wound and tissue infections | Domestic animals, insects and soil. Nosocomial infections: hands of health-care workers, indwelling catheters, etc. | |
| Candida tropicalis | Bloodstream infection and less commonly tissue invasive candidiasis. Rarely biofilm infections or oral or vaginal thrush | Tropical and subtropical marine environments. It can also be cultured from various fruits, faeces and soil | |
| Candida utilis/Pichia jadinii | Urinary tract infections | Cellulose-rich substrates such as wood, leaf litter, and paper pulp | |
| Cryptococcus neoformans | Lung infection, fungal meningitis and encephalitis | Soil | |
| Debaryomyces hansenii | Nonpathogenic | All types of cheeses and chilled food | |
| Hanseniaspora guilliermondii | Nonpathogenic | Dates, grapes, tomatoes, figs and in soil | |
| Kluyveromyces fragilis or marxianus | Poorly pathogenic pulmonary infection in an immunosuppressed cardiac transplant patient | Grape, milk, cheese and other food products. | |
| Pichia stipitis | Nonpathogenic | Guts of passalid beetles, forests or areas high in agricultural waste, among others | |
| Rhodotorula rubra | Fungal peritonitis, fungemia, endocarditis and meningitis in patients on dialysis and chemotherapy | Airborne contaminant of skin, lungs, urine and feces | |
| Saccharomyces cerevisiae | Nonpathogenic | Skin of grapes |
| Group | Micro-Organisms | Pathogenic disease | Source |
|---|---|---|---|
| Fungi | Alternaria alternate | Upper respiratory tract infections and asthma | Leaves of trees |
| Aspergillus flavus | Hepatitis, immunosuppression, hepatocellular carcinoma, and neutropenia | Cereal grains and legumes | |
| Aspergillus fumigatus | Pulmonary infections | Soil and decaying organic matter | |
| Aspergillus niger | Lung diseases | Certain fruits and vegetables | |
| Aspergillus terreus | Rare, only in people with deficient immune systems pulmonary diseases | In tropical and subtropical areas. It is common in stored crops | |
| Byssochlamys fulva | Nonpathogenic | Acidic canned fruits | |
| Botrytis cinerea | “Winegrower's lung”, a rare form of hypersensitivity pneumonitis | Many plant species, such as wine grapes | |
| Chaetosphaeridium globosum | Nonpathogenic | Fresh water | |
| Cladosporium cladosporioides | Very rare, agents of phaeohyphomycosis | Herbaceous and woody plants and dead organic matter | |
| Eurotium tonophilum (Aspergillus tonophilus) | Nonpathogenic | Soybeans, rice | |
| Fusarium moniliforme | Nonpathogenic | Rice, sugarcane and maize | |
| Fusarium oxysporum | Rare, some cases of fungal keratitis, Onychomycosis, hyalohyphomycosis | Banana trees and many plants | |
| Microsporum gypseum | Tinea capitis, tinea corpus, ringworm, and other skin and hair diseases | Warm humid weather | |
| Mucor circinelloides | Mucormycosis | Plants | |
| Penicillium citrinum | Nonpathogenic | Cereal plants | |
| Penicillium digitatum | Nonpathogenic | Citrus fruits | |
| Penicillium funiculosum | Nonpathogenic | Tropical areas: water, soil, food products, etc. | |
| Penicillium pinophilum | Nonpathogenic | Tomato and cotton plants | |
| Pyrobaculum islandicum | Nonpathogenic | Submarine hydrothermal systems | |
| Rhizoctonia bataticola | Rare cases of cutaneous and renal infections | Many plants such as soybean, peanut, and corn | |
| Rhizopus oryzae | Mucormycosis | Dead organic matter | |
| Rhizopus stolonifer | Nonpathogenic | Bread, soft fruits such as bananas and grapes, etc. | |
| Sporotrichum pulverulentum | Nonpathogenic | Plants | |
| Stachybotrys chartarum | Chronic fatigue, fever, irritation to the eyes, nausea, vomiting, pulmonary haemorrhage | Building materials rich in cellulose when they are wet | |
| Trichoderma lignorum | Nonpathogenic | Soil | |
| Trichophyton rubrum | Tinea pedis (athlete's foot), tinea cruris, ringworm | Environmental heat and humidity: swimming pools, tight shoes | |
| Trichophyton mentagrophytes | Cutaneous infections | Soil, floor of swimming pools, animals, footwear | |
| Trichoderma virens | Nonpathogenic | Soil | |
| Trichoderma viridis | Nonpathogenic | Soil | |
| Yeasts | Aureobasidium pullulans | Dyspnea, cough, fever, chest infiltrates, acute inflammatory reaction and hypersensitivity pneumonitis | In different environments (e.g. soil, water, air and limestone) |
| Candida albicans | Infections in the skin, mucouses and visceras, causing mild inflammation. Also vaginal thrush | Saprophyte of the human and animal digestive tract | |
| Candida glabrata | Infections of the urogenital tract and bloodstream | Normal flora of healthy individuals and also nosocomial environments | |
| Candida parapsilosis | Sepsis and of wound and tissue infections | Domestic animals, insects and soil. Nosocomial infections: hands of health-care workers, indwelling catheters, etc. | |
| Candida tropicalis | Bloodstream infection and less commonly tissue invasive candidiasis. Rarely biofilm infections or oral or vaginal thrush | Tropical and subtropical marine environments. It can also be cultured from various fruits, faeces and soil | |
| Candida utilis/Pichia jadinii | Urinary tract infections | Cellulose-rich substrates such as wood, leaf litter, and paper pulp | |
| Cryptococcus neoformans | Lung infection, fungal meningitis and encephalitis | Soil | |
| Debaryomyces hansenii | Nonpathogenic | All types of cheeses and chilled food | |
| Hanseniaspora guilliermondii | Nonpathogenic | Dates, grapes, tomatoes, figs and in soil | |
| Kluyveromyces fragilis or marxianus | Poorly pathogenic pulmonary infection in an immunosuppressed cardiac transplant patient | Grape, milk, cheese and other food products. | |
| Pichia stipitis | Nonpathogenic | Guts of passalid beetles, forests or areas high in agricultural waste, among others | |
| Rhodotorula rubra | Fungal peritonitis, fungemia, endocarditis and meningitis in patients on dialysis and chemotherapy | Airborne contaminant of skin, lungs, urine and feces | |
| Saccharomyces cerevisiae | Nonpathogenic | Skin of grapes |
Features of different algae and protozoa.
| Group | Micro-Organism | Pathogenic diseases | Source |
|---|---|---|---|
| Algae | Amphora coffeaeformis | Nonpathogenic | Brackish water habitats and can tolerate a very wide spectrum of environmental conditions |
| Dunaliella tertiolecta | Nonpathogenic | Marine green flagellate | |
| Navicula incerta | Nonpathogenic | Phytoplankton |
| Group | Micro-Organism | Pathogenic diseases | Source |
|---|---|---|---|
| Algae | Amphora coffeaeformis | Nonpathogenic | Brackish water habitats and can tolerate a very wide spectrum of environmental conditions |
| Dunaliella tertiolecta | Nonpathogenic | Marine green flagellate | |
| Navicula incerta | Nonpathogenic | Phytoplankton |
Features of different viruses.
| Group | Micro-Organisms | Pathogenic diseasis | Transmission |
|---|---|---|---|
| Viruses | Herpes simplex | Disorders based on the site of infection | Skin, mucous membrane, body fluid |
| Human Immunology Influenza A | Disease of the respiratory tract, flu | People cough and sneeze and by indirect spread from respiratory secretions on hands, tissues | |
| Simian 40 | Tumors, but most often persists as a latent infection | Probably first “from polio vaccine” and then by horizontal infection | |
| Varicella zoster | Chickenpox (varicella) | Directly touching the blisters, saliva or mucus of an infected person. Also through the air by coughing and sneezing |
| Group | Micro-Organisms | Pathogenic diseasis | Transmission |
|---|---|---|---|
| Viruses | Herpes simplex | Disorders based on the site of infection | Skin, mucous membrane, body fluid |
| Human Immunology Influenza A | Disease of the respiratory tract, flu | People cough and sneeze and by indirect spread from respiratory secretions on hands, tissues | |
| Simian 40 | Tumors, but most often persists as a latent infection | Probably first “from polio vaccine” and then by horizontal infection | |
| Varicella zoster | Chickenpox (varicella) | Directly touching the blisters, saliva or mucus of an infected person. Also through the air by coughing and sneezing |
MINECO is fully acknowledged for financial support (MAT2010-17016 and MAT2010-19883). A. Muñoz-Bonilla also thanks MINECO for her Juan de la Cierva postdoctoral contract.
