Organisms that are indicators of fecal contamination

The use of typical enteric organisms as indicators of fecal contamination (rather than pathogenic agents themselves) is a generally accepted principle for monitoring and assessing the microbiological safety of water supplies. Ideally, the detection of such indicator bacteria should indicate the possible presence of all pathogenic agents associated with such contamination. Indicator microorganisms must be easily isolated from water, identified and quantified. At the same time, they should survive longer in the aquatic environment than pathogenic agents, and should be more resistant to the disinfecting effect of chlorine than pathogenic ones. Almost no single organism can meet all of these criteria, although many of them do in the case of coliform organisms, especially E. coli, an important indicator of water contamination from human and animal feces. Other organisms that meet some of these requirements, although not to the same extent as coliform organisms, may also be used as additional indicators of fecal contamination in some cases.

Coliform organisms used as indicators of fecal contamination include common coliforms, incl. and E. coli, fecal streptococci, sulfite-reducing spore-bearing clostridia, especially Clostridium perfringens. There are other anaerobic bacteria (for example, bifidobacteria) that are found in large quantities in feces. At the same time, routine methods for their detection are too complex and time-consuming. For this reason, specialists in the field of aquatic bacteriology have settled on simple, accessible and reliable methods for the quantitative detection of indicator coliform microorganisms, using the titration method (serial dilutions) or the membrane filter method.

Coliform organisms have long been considered useful microbial indicators of drinking water quality, mainly because they are easy to detect and quantify. These are gram-negative rods, they have the ability to ferment lactose at 35-37 °C (common coliforms) and at 44-44.5 °C (thermotolerant coliforms) to acid and gas, oxidase-negative, do not form spores and include species E. coli, Citrobacter , Enterobacter, Klebsiella.

According to SanPiN, general coliform bacteria should be absent in 100 ml of drinking water.

Before sterilization. The air is assessed by the content of Staphylococcus aureus entering it from the upper respiratory tract and oral cavity. It is considered an indicator of droplet air pollution. Other microbes that reflect the sanitary problems of a particular object are yeast and mold fungi, Pseudomonas aeruginosa, and salmonella.

General and thermotolerant coliform bacteria (in 3 samples of 100 ml of water)

When determining water quality, it is necessary to calculate the amount of coliform bacteria present to determine whether the water meets established standards. To count positive coliform tests (presumptive, confirmatory and fecal), a (Multiple fermentation tubes) is used. When counting, a method of statistical processing of test results carried out with serial dilution of the sample is used. Research results are presented in the form of the most probable number of coliform bacteria (MPN). For example, NP 10 means that there are 10 coliform bacteria per 100 ml of water.

In most cases, the study of the restoration of the number of bacteria was carried out on the total and fecal coliform groups of bacteria. At the same time, the question of how dangerous the restoration of the number of coliform bacteria is to health remains open, since different types of bacteria have different pathogenic properties, in addition, neither general nor fecal coliform groups of bacteria are the only pathogenic microbiological factors operating in the water environment.

The purpose of this work was to investigate the phenomenon of apparent recovery of these three major subgroups of coliform bacteria in chlorinated wastewater. Recovery of bacteria in chlorinated waters and their survival in non-chlorinated waters have been carried out. In cases where, over long periods of time after chlorination, the destruction of bacteria does not differ significantly from natural, the feasibility of chlorination is questionable, especially if the wastewater is not immediately used by humans after it is discharged.

The data presented shows how statistically significant the increase in the content of coliform bacteria is. It was found that the content of all subgroups of bacteria increases; the maximum content is observed on the fourth or fifth day (Table 13.5).

Rice. 12.3. Diagram of a typical installation for biological wastewater treatment and tests that must be carried out to determine the degree of efficiency of its operation / - determination of flow parameters g - coarse impurities 3 - sand trap 4 - primary settling tank 5 - sediment from primary settling tanks 5 - compactor 7 - sludge water 8 compacted sediment 9 - vacuum filter / O -filtrate - conditioning chemicals t - cake 13 - biological treatment and sedimentation 14 - excess activated sludge 5 - chlorination C - flow rate 55 - suspended solids content U55 - loss on ignition of suspended solids - dry residue coliorts - content of fecal coliform bacteria

A study of the quality of drinking water treated with an active water device (still version) in terms of bacterial contamination was carried out according to the main indicators standardized by SanPiN 2.1,4.559-96 Drinking water. Hygienic requirements for the quality of water from centralized domestic and drinking water supply. Quality control (total coliform bacteria, thermotolerant coliform bacteria and total microbial number) and by additional indicators characterizing water pollution by microorganisms that are most resistant to disinfecting agents.

The effectiveness of the disinfection process is determined by analysis of a group of coliform bacteria, which are indicators of water quality. The sensitivity of bacteria to chlorination is well known, while the effect of chlorination on protozoa and viruses is not entirely clear. Protozoan larvae and intestinal viruses are more resistant to chlorine than coliforms and other intestinal bacteria. However, there is very little evidence to suggest that current water treatment practices are deficient. There have been no documented outbreaks of diseases associated with the consumption of water containing viral or protozoal infections.

Almost all states now require coliform testing of treated water, with the number of tests required depending on the population served. Fecal coliform counting, although usually unnecessary from a regulatory perspective, is straightforward and can provide additional insight into the situation. Sometimes, in relation to a particular installation, limit values ​​for certain indicators are specifically set, such as the concentration of residual chlorine, turbidity, content of dissolved solids, nitrates, and color. The concentration of residual chlorine in the distribution system is measured to determine whether chlorination is sufficient. Other laboratory tests are related to monitoring chemical treatments, identifying and correcting certain problems occurring in distribution system facilities, and consumer complaints about water quality. Chemical reagents must meet the requirements of the relevant specifications and should be subjected to traditional analysis, with a fine imposed on the supplier if they deviate from the specifications. For example, lime is typically purchased at 88-90% CaO, alum at 17% AI2O3, and activated carbon to specifications for phenol content. If the chemical supply contract specifies penalties for the supplier based on laboratory test results, this can prevent the water treatment plant from receiving substandard materials.

Restoring the content of coliform bacteria in chlorinated waters

Initial

Sanitary microbiology

Reviewer: Head Department of Epidemiology PGMA,

© State Educational Institution of Higher Professional Education “PGMA named after. ak. E.A. Wagner Roszdrav"

1. Subject of sanitary microbiology p3
2. Principles and methods of conducting sanitary microbiological studies c3
3. Main groups of sanitary indicative microorganisms (SIM) c5
4. Sanitary microbiology of water p11
5. Sanitary microbiology of soil p14
6. Sanitary microbiology of air p15
7. Sanitary and microbiological research in medical institutions p16
8. Test tasks p19

Sanitary microbiology– a science that studies the microflora of the environment and its impact on human health and the ecological situation in various biotopes. The main task of practical sanitary microbiology is the early detection of pathogenic microflora in the external environment. It should be remembered that humans and warm-blooded animals are the main reservoir of pathogens of most infectious diseases and the overwhelming number of pathogens are transmitted through aerogenic and fecal-oral mechanisms.

The beginning of the development of sanitary microbiology can be considered in 1888, when the French doctor E. Mace proposed to consider E. coli as an indicator of fecal contamination of water.

Principles of sanitary microbiological research

1. Proper sampling. It is carried out in compliance with all necessary conditions regulated for each object under study. Sterility is maintained. If immediate analysis is not possible, the material is stored in the refrigerator for no longer than 6-8 hours.
2. Seriality of the analyzes performed. Most of the studied objects contain a wide variety of microorganisms, distributed extremely unevenly. A series of samples are taken from different areas of the object. In the laboratory, the samples are mixed and then the required amount of material is precisely measured (usually an average of the entire material being tested).
3. Repeated sampling. As a rule, in the objects under study, the composition of the microflora changes quite quickly; in addition, pathogenic microorganisms are distributed unevenly in them. Accordingly, repeated sampling allows one to obtain more adequate information.
4. The use of only standard research methods makes it possible to obtain comparable results in different laboratories.
5. Using a set of tests: direct (detecting pathogens) and indirect.
6. Assessment of objects based on the totality of the results obtained - taking into account other hygienic indicators (organoleptic, chemical, physical, etc.)

Methods for conducting sanitary microbiological studies

Practical sanitary microbiology uses two main methods for assessing the sanitary and epidemiological state of the environment.

I. Methods for direct pathogen detection. They are the most accurate and reliable criteria for assessing the epidemic danger of the external environment. The main disadvantage is low sensitivity.

Difficulty isolating pathogenic microorganisms on nutrient media are determined by the following factors:

1. Relatively low content of pathogenic microorganisms in the external environment, constituting 1/30,000 of the total species composition of the microflora of the external environment. In addition, it is unevenly distributed.
2. Isolation of one pathogen does not always indicate the presence of other types of pathogens. That is, it is necessary to conduct research on almost every pathogen, which is not feasible.
3. Pathogen variability. The latter, entering the external environment, acquire new properties that make them difficult to recognize.
4. Competitive relationships between pathogens and saprophytes when grown together on nutrient media.
5. Insufficient selectivity of culture media and the need to use laboratory animals and tissue cultures.

II. Methods for indirect indication of the possible presence of a pathogen in the external environment.

Two criteria are used by which one can indirectly judge the possible presence of a pathogen in the external environment:

1. Total microbial count (TMC)
2. Content of sanitary indicative microorganisms (SIM)

- Total microbial count (TMC) determined by counting all microorganisms in 1 gram or 1 ml of substrate.

In this case, they proceed from the assumption that the more an object is contaminated with organic substances, the higher the TMC and the more likely the presence of pathogens. However, this is not always the case, since the TMC may be large due to saprophytes, while pathogens may be absent. Therefore, it is more adequate to evaluate TMC as an indicator of the intensity of pollution of the external environment with organic substances.

OMC determined by two methods:

1. Direct counting. They are carried out under a microscope using special cameras, for example, Petrov or Goryaev, or special electronic counters. The pre-tested sample is homogenized and a dye (usually erythrosine) is added. Direct counting can also be carried out on membrane filters through which the test liquid or suspension is passed. The method is used in emergency cases. If an urgent answer is needed about the quantitative content of bacteria (for example, in case of accidents in the water supply system, when assessing the efficiency of treatment facilities, etc.). The main disadvantage is the inability to count bacteria when their clusters form or when they “stick” to the particles of the substrate under study. It is impossible to count small microorganisms, not to mention viruses. And finally, it is impossible to distinguish living from dead microorganisms.
2. Quantitative inoculation on nutrient media. From the prepared serial tenfold dilutions of the test liquid or suspension, 1 ml is transferred into sterile Petri dishes and poured into MPA, melted and cooled to 45-50 0 C. The liquids are mixed evenly and after the agar has hardened, the dishes are placed in a thermostat. After incubation, the number of grown colonies is counted and, taking into account dilutions, the number of viable microbes per unit volume of the object under study is calculated. In this case, only mesophilic aerobic and facultative anaerobic bacteria capable of multiplying on MPA are identified. Thus, the resulting figures are significantly lower than the true number of microorganisms in the object under study.

-Microorganisms are called sanitary indicators, by which you can indirectly judge the possible presence of pathogens in the external environment. It is assumed that the more an object is contaminated with human and animal extracts, the more sanitary indicative microorganisms there will be and the more likely the presence of pathogens.

Main characteristics of SPM:

1. The microorganism must constantly live in the natural cavities of humans and animals and be constantly released into the external environment.
2. The microbe should not multiply in the external environment (excluding food products), or multiply only slightly.
3. The duration of survival of a microbe in the external environment should be no less, but even longer, than that of pathogenic microorganisms.
4. The stability of SPM in the external environment should be similar to or exceed that of pathogenic microorganisms.
5. The microbe should not have “doubles” or analogues in the external environment with which they can be confused.
6. The microbe should not change in the external environment, at least during the survival period of pathogenic microorganisms.
7. Methods for identifying and differentiating microorganisms must be simple.

SPMs are conventionally divided into 3 groups.

There are no clearly defined boundaries between them; Some microorganisms are both indicators of fecal and airborne pollution. All sacred natural sites are regarded as indicators of biological pollution.

Group A includes inhabitants of the intestines of humans and animals; microorganisms are regarded as indicators of fecal contamination. It includes the so-called coliform bacteria - coliforms. (for drinking water according to the new regulatory document - Sanitary microbiological analysis of drinking water. Guidelines MUK 4.2.1018-01 - this group is called common coliform bacteria OKB); Coliform bacteria - OCB, Escherichia, Enterococcus, Proteus, Salmonella; as well as sulfite-reducing clostridia (including Cl.perfringens), thermophiles, bacteriophages, Pseudomonas aeruginosa, Candida, Acinetobacter and Aeromonas.

Group B includes inhabitants of the upper respiratory tract and nasopharynx; microorganisms are regarded as indicators of airborne pollution. It includes alpha- and beta-hemolytic streptococci, staphylococci (plasmacoagulating, lecithinase-positive, hemolytic and antibiotic-resistant; in some cases, the type of staphylococcus is determined - aureus).

Group C includes saprophytic microorganisms living in the external environment; microorganisms are regarded as indicators of self-purification processes. It includes ammonifying bacteria, nitrifying bacteria, some spore-forming bacteria, fungi, actinomycetes, etc.

SPM titer– the smallest volume of the material under study (in ml) or weight quantity (in g) in which at least one SPM specimen was found.

SPM Index– the number of SPM individuals found in a certain volume (quantity) of the object under study. For water, milk and other liquid products – 1 liter; for soil, food products - in 1 g. The index is the reciprocal of the titer, therefore the recalculation of the titer into the index and back can be done using the formula: T = 1000/I; I=1000/T – for liquids. Accordingly, for soil and food products T = 1/I, I = 1/T.

As an additional indicator, the most probable number index (MPI) is currently also used, which has confidence limits within which the true number of the desired microbe can fluctuate with 95% probability. To determine NHF, studies are carried out 3, 5, and 10 times. The indicator is determined using special Hoskens-Mouret tables.

Main groups of DMAs

Coli bacteria

Under the general name “coliform bacteria” – coliforms – bacteria of the family Enterobacteriaceae childbirth Escherichia, Citrobacter, Enterobacter, Klebsiella. According to new regulatory documents issued after 2001, this group is called common coliform bacteria - TCB. The characteristics of these groups are the same; coliform bacteria include gram-negative, non-spore-forming rods that ferment lactose and glucose to acid and gas at a temperature of 37 0 C in 24 hours and do not have oxidase activity. The use of two names for the same group of bacteria is due to the use of regulatory documents of different years of issue. For example, in the current Order No. 720 of July 31, 1978 “On improving medical care for patients with purulent surgical diseases and strengthening measures to combat nosocomial infections,” this group is called coliform and in the results of studies conducted in accordance with this Order, it will be noted – coliforms detected (not detected). And when examining drinking water according to the guidelines from 2001, it will be noted - OKB detected (not detected).

Escherichia coli

The microorganism is the ancestor of all SPMs. This is the main representative of the OCB group; depending on the purpose and object of the study, this group includes a subgroup of TCB - thermotolerant coliform bacteria.

Common coliform bacteria - OKB – gram-, oxidase-, non-spore-forming rods, capable of growing on differential lactose media, fermenting lactose to KG at t 0 37 0 C for 24 hours.

Thermotolerant coliform bacteria - TCB – are included in the group of OKB, have all their characteristics, in addition, they are capable of fermenting lactose to KG at t 0 44 0 C for 24 hours.

As an additional test, the determination of glucose fermentation at different cultivation temperatures is used, since it is known that OCB isolated from chlorinated water (tap, swimming pools, etc.) are not capable of causing fermentation of glucose with the formation of gas at a temperature of 44 0 C.

Significant disadvantages E.coli as SPM are:

1. Abundance of analogues in the external environment;

2. Insufficient resistance to adverse environmental influences, for example, to various chemicals and pH changes. At the same time, some pathogenic microorganisms, especially enteroviruses, are more resistant to them;

3. High variability, as a result of which the issues of its ecology and diagnostics are not completely resolved;

4. Relatively short survival time in food, while some pathogenic microorganisms (e.g. S. sonnei, S. schottmuelleri, enteroviruses) persist for a long time;

5. E. coli multiplies in water with an organic substance content of at least 280 µg/l;

6. E. coli is a fuzzy indicator. For example, outbreaks of salmonellosis of water origin are known with pathogen contents of up to 17 bacteria per 1 liter, while the content E.coli did not exceed 4 bacteria per 1 liter, that is, it remained almost normal.

Bacteria genus Enterococcus

SPMs were proposed by Houston (1910). The genus includes 16 species, the main lesions in humans are caused by E. faecalis, E. faecium, E. durans. These bacteria meet a number of requirements for SPM.

1. Enterococci are permanent inhabitants of the human intestine, despite the fact that they are quantitatively smaller than E. coli.

2. Bacteria are practically unable to reproduce in the external environment (the temperature should be 20 0 C and the content of organic substances should be 375 µg/l).

3. Enterococci do not show pronounced variability in the external environment, which facilitates their recognition.

4. Enterococci have no analogues in the external environment.

5. Enterococci die off in the external environment much earlier than E. coli therefore they always indicate fresh fecal contamination.

6. The most important advantage of enterococci is their resistance to adverse external influences. Enterococci are differentiated using Sherman resistance tests.

a) Enterococci are resistant to heating up to 65 C for 30 minutes, which makes them an indicator of the quality of heat treatment or pasteurization.

b) Enterococci are resistant to high concentrations of NaCl (6.5-17%) - SPM in the study of sea water.

c) Enterococci are resistant to pH fluctuations (3-12), which allows them to be used as an indicator of fecal contamination in acidic and alkaline products (wastewater). In such conditions E.coli quickly loses its properties and becomes difficult to recognize.

Based on the number and ratio of enterococci and E. coli, the severity and timing of fecal contamination are judged.

Bacteria genus Proteus

They are the third (most important) group of sacred natural sites. They were proposed as SPM back in 1911. The genus includes 4 species; are of greatest importance P.vulgaris, P.mirabilis. Wherein P. vulgaris is usually considered as an indicator of contamination of an object with organic substances (since it is more often found in rotting residues), and P.mirabilis – as an indicator of fecal contamination (more often found in feces). P.rettgeri is more often detected in feces during intestinal infections - therefore its detection indicates an epidemiological problem. Representatives of the genus Proteus give a characteristic “creeping” growth on Endo and Lewin’s media, often covering the entire plate. You can isolate Proteus using the Shukevich method - by inoculating freshly cut MPA into the condensate (at the bottom of the test tube) - if there is Proteus in the sample, it will cover the entire agar slope.

The presence of proteas in water, food products, and washings always indicates contamination of an object with decomposing substrates and an extremely poor sanitary condition. Food products contaminated with Proteus are usually discarded; Water containing Proteus should not be drunk. Determination of Proteas is recommended when studying water from open reservoirs and therapeutic mud. And when examining food products, the detection of Proteus is provided for by GOST.

Clostridium perfringens

How the SPM was proposed back in 1895, almost simultaneously with E.coli. Wilson and Blair (1924-1925) proposed an iron-sulfite medium, which allows the differentiation of clostridia of fecal origin from clostridia living in the external environment. Intestinal clostridia reduce sulfites and cause blackening of the medium, while free-living clostridia do not have sulfite reductase and do not change the color of the medium. Some other microorganisms can also cause blackening of the medium, therefore, to suppress the growth of accompanying microflora, it is recommended to cultivate crops at 43-44.5 0 C or warm up samples at 80 0 C for 15-20 minutes. That., Clostridium perfringens easy to highlight and differentiate. However, Clostridium perfringens As SPM there are certain disadvantages.

1. The bacillus is not always present in the human intestine.
2. Clostridium perfringens persists for a long time in the external environment due to sporulation. Therefore, the detection of this microorganism indicates that fecal contamination once occurred. This is an indicator of the possible presence of enteroviruses.
3. Clostridium perfringens can reproduce in the external environment (in some types of soil). For spores to germinate, a “temperature shock” is required, i.e. warming up at 70 0 C for 15-30 minutes.

Currently, it is proposed to judge the age of fecal contamination of an object by comparing the number of spore and vegetative forms Clostridium perfringens. For this purpose, the number of clostridia in heated and unheated samples is determined.

A) In heated samples, the index will be represented only by spore forms, indicating long-standing contamination (in fresh feces, 80-100% are vegetative cells).

B) In unheated samples, vegetative and spore forms are detected.

Quantitative recording of clostridia is provided for in the study of soil, therapeutic mud, and open water.

Clostridium perfringens should not be found in 100 ml of water in food processing plants. The microbe is also identified in some food products, but as a possible causative agent of food poisoning. Critical level Clostridium perfringens in ready-made dishes is equal to 10 cells in 1 ml or 1 g of product. Ready-made canned food should not contain Clostridium perfringens.

Based on the ratio of the amounts of E. coli, enterococci and clostridia, the age of fecal contamination is judged.

Bacteria genus Salmonella

They are the most common pathogens of acute respiratory infections and therefore can be indicators of the possible presence of other infectious agents with similar pathogenesis and epidemiology.

In recent decades, Salmonella has become widespread in the external environment. The number of bacteria carriers has increased (up to 9.2%), releasing millions and billions of cells into the external environment with every gram of feces; carriage in animals is even more pronounced. In wastewater from meat processing plants, salmonella is found in 80-100% of samples, in treated wastewater - in 33-95% of samples; bacteria are also found in chlorinated wastewater.

Features of Salmonella as SPM

1. These microorganisms enter the external environment only with human and animal feces. Their detection always indicates fecal contamination.
2. Salmonella does not grow in soil; in water they reproduce only at high temperatures and high levels of organic matter.
3. When determining Salmonella, it is necessary to determine not only the percentage of positive findings, but also the NFP. Only NHF makes it possible to predict the rise of salmonellosis and other acute diseases with a similar etiology.

Bacteria viruses

It is proposed to use bacteriophages of intestinal bacteria (Escherichia, Shigella, Salmonella) as SPMs. Intestinal phages are constantly found where there are bacteria to which they are adapted. However, they have some disadvantages as indicators of the possible presence of pathogenic bacteria. For example, bacteriophages survive in the external environment longer (8-9 months) than the corresponding bacteria (4-5 months). But as indicators of fecal contamination, bacteriophages have significant value.

1. Bacteriophages are isolated from wastewater with the same frequency as many pathogenic viruses (poliomyelitis, Coxsackie, hepatitis A).

2. Similarity to enteropathogenic viruses complements resistance to disinfectants.

3. Methods for detecting phages are quite simple. Inoculations are carried out in broth with an indicator bacterial culture. After incubation, subcultures are made on dense agar, CFUs in the experiment and control are compared and conclusions are drawn.

Bacteria genus Staphylococcus

Staphylococci are representatives of normal microflora. The main place of their localization is the mucous membranes of the upper respiratory tract of humans and some warm-blooded animals, as well as the skin. Staphylococci are also present in the intestines of healthy people. Staphylococci enter the environment when talking, coughing, sneezing, and also from the skin. Contamination of water in reservoirs and swimming pools occurs when people bathe, while in swimming pools the number of staphylococci can reach tens of thousands in 1 liter of water. The spread of staphylococci in the environment is closely related to the problem of nosocomial infections of staphylococcal nature, which is associated with the carriage of pathogenic staphylococci in people, especially among medical personnel. All this allows us to classify staphylococci as indicator bacteria of airborne pollution.

Staphylococci belong to the family Micrococcaceae family Staphylococcus. View S. aureus refers to pathogenic.

As sanitary indicator microorganisms, staphylococci have some features:

1. They are unpretentious to nutrient media; methods for indicating them in the environment are simpler than, for example, for streptococci
2. Staphylococci have significant resistance to various physical and chemical factors. Based on the resistance of staphylococci to disinfectants (especially chlorine preparations), it is proposed to use them as SPM for water pollution in recreational areas of water bodies (including sea waters) and swimming pools.
3. They are an objective indicator of indoor air pollution, since there is a correlation between the sanitary and hygienic condition of the premises, the number of people in them, the number of carriers of pathogenic staphylococci and the content of staphylococci in the air.

Bacteria genus Streptococcus

Streptococci, like staphylococci, are inhabitants of the upper respiratory tract of humans and many animals. They are constantly and in large quantities present in the oral cavity and nasopharynx of patients with chronic streptococcal infections of the upper respiratory tract, as well as healthy people, and therefore can enter the indoor air with bacterial aerosol when talking and coughing.

The main difficulty in using streptococci as sanitary indicator microorganisms is that streptococci represent a large group that includes a large number of species: from saprophytes to pathogenic streptococci that cause diseases such as scarlet fever, erysipelas, sepsis and many purulent-inflammatory processes.

Streptococci belong to the family Streptococcaceae, family Streptococcus. View S.pyogenes is of greatest importance in human pathology .

In the environment, streptococci are represented mainly by α-hemolytic streptococci (they do not completely destroy red blood cells, they form greenish zones around the colonies). This is due to the fact that almost 100% of healthy people have α-hemolytic streptococci on the surface of the tonsils, while β-hemolytic streptococci (cause lysis of red blood cells and form a hemolysis zone) are found in only 25-75%. It is generally accepted that it is advisable to consider sanitary Indicative air microbes include α- and β-hemolytic streptococci.

Features of streptococci as SPM:

1. Streptococci are not very stable in the environment; they can only survive for several days in the dust of rooms, on linen, and household items of the patient. However, the period of preservation of their viability is close to the life expectancy of a number of pathogenic bacteria that enter the environment by airborne droplets (for example, such as the causative agent of diphtheria, etc.)
2. An indicator of more recent indoor air pollution is α-hemolytic streptococcus as the least resistant. Streptococci are not found in the air of premises uninhabited by humans.
3. Methods for the indication and identification of streptococci are more complex and labor-intensive compared to those of staphylococci.

Thermophiles

A special place among SPMs is occupied by thermophilic microbes, the presence of which in the soil or water of reservoirs indicates their contamination with manure, compost or decomposed human feces.

Thermophilic microorganisms include gram-positive bacteria, cocci, bacilli, spirilla, actinomycetes, and a few types of fungi that can actively reproduce at temperatures of 60 0 C and above. Most thermophiles are aerobes.

Thermophilic microorganisms multiply in compost heaps and manure, in which, due to their vital activity, the surface layers are heated to 60-70 0 C. Under such conditions, the process of biothermal neutralization of organic masses undergoing self-heating takes place, pathogenic microorganisms and E. coli die.

Thus, the presence of thermophiles indicates long-standing soil contamination with composts, while coliform bacteria (OCB) are detected in insignificant quantities. And, on the contrary, a high titer of coliform bacteria (OCB) with a small number of thermophiles is an indicator of fresh fecal contamination.

Thermophiles also serve as sanitary indicator microorganisms for characterizing individual stages of the mineralization process of organic waste.

Analysis of drugs from the benzenesulfonylamide group

Analysis of drugs from the benzenesulfonylamide group. In the control and analytical laboratory, the content of sulfadimethoxine in tablets was determined by nitritometry

Analysis of drugs from the group of salts of aliphatic carboxylic acids and hydroxy acids, ascorbic acid, aliphatic amino acids and their derivatives

Coliform bacteria Coliform bacteria

gram-asporogenic oxidase-negative enterobacteria, growing on Endo medium and fermenting lactose with the formation of lactose and gas at 37°C for 48 hours. K.b. are standardized according to international standards as an indicator of fecal contamination of K. b. together with similar bacteria, but fermenting glucose with the formation of acid and gas during the day, they form a group of Escherichia coli, which is standardized as an indicator of fecal contamination.

(Source: Dictionary of Microbiology Terms)

See what “Coliform bacteria” is in other dictionaries:

coliform bacteria- 3.2 coliform bacteria: Lactose-positive bacteria that are oxidase negative when tested using a standard test. Source: GOST R 52426 2005: Drinking water...

Coliform bacteria are thermotolerant- bacteria that have all the characteristics of common coliform bacteria and are capable of fermenting lactose to acid and gas at a temperature of 44 C for 24 hours. Indicate fecal matter that has recently entered the water... ... Official terminology

Common coliform bacteria- Common coliform bacteria are gram-negative, non-spore-forming rods that produce aldehyde on differential lactose media, do not have oxidase activity, ferment lactose or mannitol with the formation of acid and gas when... ... Official terminology

thermotolerant coliform bacteria- Bacteria that have the characteristics of common coliform bacteria, and are also capable of fermenting lactose to acid, aldehyde and gas at a temperature of 44 ° C for 24 hours. Note An indicator group of bacteria indicating fecal... ...

thermotolerant coliform bacteria- 64 thermotolerant coliform bacteria; thermotolerant coliforms: Bacteria that have the characteristics of common coliform bacteria, and are also capable of fermenting lactose to acid, aldehyde and gas at a temperature of 44 ° C for 24 hours... ... Dictionary-reference book of terms of normative and technical documentation

common coliform bacteria- common coliforms: Gram-negative, oxidase-negative, non-spore forming rods, capable of growing on differential lactose media, fermenting lactose to acid, aldehyde and gas at a temperature of 37 °C for 24-48 hours. Note... Technical Translator's Guide

Escherichia coli (Latin: Escherichia coli) is a microorganism discovered in 1885 by Escherich from the remains of human activity. This microorganism is a permanent inhabitant of the large intestine of humans and animals. In addition to E. coli, the group... ... Wikipedia

See also: Escherichia coli Bacteria of the Escherichia coli group (coliforms, also called coliform and coliform bacteria) are a group of bacteria of the enterobacteria family, conditionally distinguished by morphological and cultural characteristics, used ... ... Wikipedia

GOST 30813-2002: Water and water treatment. Terms and Definitions- Terminology GOST 30813 2002: Water and water treatment. Terms and definitions original document: 65 Escherichia coli; E. coli: Aerobic and facultative anaerobic heat-stable coliform bacteria that ferment lactose or mannitol at... ... Dictionary-reference book of terms of normative and technical documentation

GOST R 52426-2005: Drinking water. Detection and quantification of Escherichia coli and coliform bacteria. Part 1. Membrane filtration method- Terminology GOST R 52426 2005: Drinking water. Detection and quantification of Escherichia coli and coliform bacteria. Part 1. Membrane filtration method original document: 3.4 Escherichia coli (E.coli): Bile-resistant bacteria that... Dictionary-reference book of terms of normative and technical documentation

Coliform bacteria (coliform bacteria)

The detection of coliforms in food products indicates their fecal contamination. Coliforms can get into products from water, equipment, the hands of workers, and other sources. Coliforms are divided into two subgroups:

• 1) common coliform bacteria, which break down glucose, lactose and mannitol to form acid and gas at 37°C for 24 hours;
• 2) thermotolerant coliform bacteria that break down glucose and lactose to form acid and gas at 43-44.5°C.

The coliform group includes childbirthEscherichia , Enterobacter, Citrobacter, Klebsiella , Serratia (Table 12.2).

Genus Escherichia. The type species of this genus is Escherichia coli. It plays an important role in the intestinal microbiocenosis of humans and animals.

E. coli- small gram-negative rods with rounded ends measuring (2-3) x (0.5-0.7) microns. They do not form spores and are immobile. There are variants that are motile due to peritrichially located flagella, but do not have capsules. Facultative anaerobes. They receive energy both through respiration and fermentation. When fermenting carbohydrates E. coli accumulate acids - lactic, acetic, succinic (positive reaction with methyl red) and gases - CO 2 and H 2 (fermentation test). Escherichia grows well on simple nutrient media. The optimal growth temperature is 37°C, the optimal pH value is 7.0-7.4.

Table 12.2

Signs of labor related to coliforms

	Mobility	Fermentation	Education	Education anetoina	Split citrates	Reaction with methyl red
Escherichia
Klebsiella
Enterobacler
Citrobacter
Serratia

Genus Enterobacter. Representatives of the genus are found in fresh water, soil, wastewater, on plants, vegetables; They are isolated from the intestines of humans and animals. Species of the genus have been isolated in recent years for acute gastrointestinal diseases, dyspepsia, biliary and urinary tract infections, purulent lesions of the meninges, sepsis in humans and animals. Typical view - E. cloacae.

Cells Enterobacter- straight rods measuring (2-3) x (0.5-0.6) microns, peritrichous, gram-negative, do not form spores or capsules. The optimal growth temperature is 30-37°C. Biochemical characteristics of species of this genus: the formation of acetoin during the fermentation of carbohydrates (positive Voges-Proskauer reaction), the breakdown of sodium citrate in Simmons' medium.

Genus Citrobacter (citrus- (lemon) and bacter). Representatives of this genus are present in human and animal feces, soil, wastewater, and food products. Under certain conditions, they can cause diseases such as gastroenteritis and dyspepsia. With the development of purulent-inflammatory processes, the most significant is the type C. freundii, which is the type species of this genus. Citrobacter cells are straight rods measuring (1-6) x (0.5-0.8) microns, single or in pairs. Peritrichous. They do not form spores and cysts, and do not form capsules. WITH. freundii produces hydrogen sulfide. On blood agar, clear zones of hemolysis form around the colonies.

Genus Klebsiella named after the bacteriologist E. Klebs. Bacteria of this genus are isolated from water, soil, and food products. They are present in the biocenoses of the nasopharynx and intestines. Causes the disease klebsiellosis in children under 1 year of age. The disease occurs in the form of diarrhea, meningitis, bronchopneumonia, purulent-septic inflammation. Representatives of the genus: K. pneumonia,

K. mobilis and saprophytic species: K. planticola, K. terrigena. These are straight rods measuring (0.6-6.0) x (0.3-1.0) microns, single or in pairs. They differ from other enterobacteria by characteristic features: they have a classic polysaccharide capsule and lack flagella. Typical view - Klebsiella pneumonia.

Genus Serratia. The name of the genus is associated with the name of the Italian physicist Serafino Serrati. They are found in soil, water, on the surface of plants, and also in the digestive tract of humans, insects and rodents as commensals. In persons with a weakened immune system, serrations can cause purulent inflammation of various locations. Typical view - Serratia marcescens. Serratia marcescens - these are straight small rods measuring (0.5-0.8) x (0.9-2.0) microns. Peritrichs, under certain conditions, are capable of forming a capsule. Most colonies Serratia colored in various shades of red due to the formation of the pigment prodigiosin.

When characterizing coliforms, the following differential diagnostic features are taken into account:

• 1) incubation of crops at a single temperature - 37°C;
• 2) the ability to ferment lactose - the growth pattern on Endo medium (the so-called lactose test). Colonies that are counted are dark red, with or without a metallic sheen;
• 3) oxidase test: colonies on Endo medium are examined for the presence of oxidase. For further identification, oxidase-negative colonies are left. Colonies with a positive oxidase test belonging to gram-negative bacteria of the genera Pseudomonas, Aeromonas, Vibrio, are not taken into account;
• 4) preparations from characteristic colonies are stained using Gram stain - gram-negative rods are taken into account;
• 5) fermentation test on Hiss medium with glucose to detect the ability of bacteria to ferment glucose with the formation of acid and gas.

In addition to coliform bacteria, the causative agents of intestinal diseases caused by the consumption of contaminated food products can also be bacteria of the genera Morganella And Providencia from the family Enteribacteriaceae.