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Microbiology (Bacteriology/Virology/Mycology)

A microbiological test laboratory is a laboratory devoted to the culturing, examination, and identification of microorganisms including bacteria, fungi, yeasts, etc. The microbiology laboratory has a crucial role in effective infection prevention and control. Applications for Microbiology Managements are :

1. Bioburden Testing : 

Bioburden testing, or total viable count testing, is the measure of microbial contamination levels on or in a product. Bioburden can be introduced from the raw materials used in the manufacturing process, or be introduced via the workforce or manufacturing environment.

Bioburden test results may be used to:

  • Demonstrate microbial quality control of the manufacturing process through routine monitoring and trending (ISO 11737)
  • Determine radiation dose for terminally sterilized product (ISO 11137)
  • Investigate root cause of contamination excursions from routine production (Alert and Action levels)
  • Test raw and finished product materials for microbiological examination of non-sterile products (USP<61>)
  • Methods for the absence of specified or objectionable microorganisms can be developed. These methods not only give total viable counts, but also identify the presence or absence of specified microorganisms, providing complete, robust test results. (USP<62>, USP<60>)

Bioburden testing is used for:

  • Medical devices
  • Pharmaceuticals
  • Packaging
  • Raw materials
  • Human Tissue
  • Animal Tissue
  • Cosmetics

2. Air Quality Testing :

The systematic, long-term assessment of pollutant levels by measuring the quantity and types of certain pollutants in the surrounding, outdoor air.

  • Indoor Air Quality Testing:Specifically designed for indoor spaces, our tests assess factors such as VOCs, mold, allergens, and other contaminants that may impact indoor air quality.
    • Air quality testing involves various methods such as collecting air samples, using specialized equipment to measure pollutants, analyzing particulate matter, and assessing ventilation systems to evaluate the overall quality of the air. Air quality is measured using instruments that detect various pollutants, including volatile organic compounds (VOCs), particulate matter, carbon monoxide, ozone, and more. These instruments provide readings indicating the concentration levels of these pollutants.


Good air quality is indicated by low levels of pollutants, minimal presence of allergens, balanced humidity, adequate ventilation, and a comfortable environment free from odors or irritants.

  • Aeronautical environments: These environments are typically characterized by high temperatures, low pressures, and high humidity.
  • Military environments: These environments are typically characterized by extreme temperatures, humidity, dust, sand, and shock.
  • Automotive environments: These environments are typically characterized by high temperatures, vibration, and shock.
  • Industrial environments: These environments are typically characterized by high temperatures, humidity, dust, and chemicals.
  • Consumer electronics environments: These environments are typically characterized by moderate temperatures, humidity, and vibration.

3. Analytical Testing : Also known as materials testing—involves using skilled techniques to identify the characteristics of a chemical sample. Common applications include the assurance of safety and quality of food, water, and pharmaceuticals, alongside the provision of precise measurements and documentation.

4. Antimicrobial Testing : Antimicrobial susceptibility testing (AST) is a laboratory procedure performed by technologists to identify which antimicrobial regimen is specifically effective for different specimen. Commercial systems also became available utilizing both phenotypic and genotypic characterization of bacterial resistance. While routine antimicrobial susceptibility testing for gram-positive (e.g., Staphylococcus aureus) and gram-negative bacteria (e.g., Pseudomonas aeruginosa) are commonly available in peripheral laboratories, drug susceptibility testing (DST) for Mycobacterium tuberculosis are usually carried out within more complex facilities like reference laboratories.

5. Bacteria Testing :

To do the test, you will need to give a sample. The type of sample depends on where the infection seems to be located. To find out what type of bacteria you may have, a professional will need to examine a large number of bacteria cells.

Enzyme-linked immunosorbent assay (ELISA) ELISA can test for specific organisms either by detecting bacterial antigen during an infection or antibacterial antibody. The detection of the antibody confirms contact with an organism at some time but it is not necessarily the reason for a current infection.

3 types of bacteria culturing method

Agar plates – Organisms are placed or streaked onto petri dishes

Agar based dipsticks – Essentially miniature agar plates in the form of dipsticks

Selective and differential media – Organisms are cultured in/on specific media to select for or differentiate between certain ones

6. Biofilm Testing : Biofilms are not just bacterial slime layers but biological systems; the bacteria organize themselves into a coordinated functional community. Tissue Culture Plate (TCP) assay as described by Christensen’s et al., 1995 is the most widely used method and is considered as the standard method for detection of biofilm formation. Plaque that forms on teeth is an example of a biofilm. Most bacteria are capable of forming biofilms. However, certain species have more of a disposition toward biofilms than others. In addition to plaque-forming bacteria on teeth, streptococci staphylococci, and lactobacilli also frequently form biofilms. Biofilms are commonly characterized by physical traits like size, adhesion, and a matrix made of extracellular substances. They display distinct phenotypic features, such as metabolic activity and antibiotic tolerance. However, the relative importance of these traits depends on the environment and bacterial species.

7. Contaminant Identification :

A strategic, technical, multi-disciplinary approach is required to fully identify an unknown contaminant. Main Contamination Detection Technologies. The two mainstream physical contamination detection technologies available are: Metal Detection and X-ray Inspection. Our skilled chemists choose the most applicable method based on the material to be analyzed and the nature of the contamination. The chemical analysis lab employs the following methods and is ISO 17025 accredited.

Ion Chromatography (IC)

Useful for identifying contamination consisting of charged particles. In addition to being general contaminants, common anions, including chloride, sulfide, nitrate, nitrite, and fluoride can be precursors to corrosion and cause defects in electrical performance. Ion chromatography is an effective and sensitive instrumental technique that allows the separation and quantitation of ionic contamination. IC analysis requires a liquid sample; however, solid components can be measured for surface contamination by specialized rinsing and wiping techniques. IC can be combined with Parr oxygen bomb preparation to determine total contamination in certain solid matrices. IC is incredibly sensitive, allowing detection to part per billion (ppb) levels in some instances. This sensitivity makes it an ideal technique for contamination analyses.

Inductively Coupled Plasma (ICP)

It is an especially flexible methodology, commonly used in analyzing metal, polymer, liquid, powder, and many other sample matrices. This makes ICP analysis ideal for the evaluation of a variety of products for trace elemental evaluation. ICP is the go-to method for determining lead content in consumer products and is equally suited to determine both the composition and the purity of raw materials. Liquid samples may be analyzed directly, while solid samples are digested with mixed acids to determine their elemental composition, including trace element contamination down to part per million (ppm) levels.

Fourier-Transform Infrared Spectroscopy (FTIR)

FTIR analysis is the go-to technique for identifying non-metallic contamination such as oil, grease, plastic, and rubber. FTIR allows comprehensive compound identification capabilities for these material types and is well suited to both the identification of complete unknowns and comparison of contaminants to suspected source materials. ATS can perform FTIR analysis by the standard transmission technique, by use of microscope, and via attenuated total reflectance (ATR). Analysis flexibility is critical in order to properly test and identify the vast majority of potential contaminants.

Liquid Chromatography-Mass Spectrometry (LC/MS)

It is a powerful analytical technique used for separation, identification, and quantification of both unknown and known compounds as well as to elucidate the structure and chemical properties of different molecules.

8. Cosmetic Testing :

Testing cosmetic products is essential for anyone wanting to produce and sell cosmetics, it is required by law and applies to all; big manufacturers and small or independent brands.  Cosmetics are often used in close contact with the skin, therefore need to be composed of materials that aren’t harmful and are free from contaminants.

Cosmetic product testing can be broken down into three main areas; safety, efficacy and stability.

Microbiology tests are performed to ensure that the product is free from harmful levels of bacteria. The source of which can be accidental contamination during the manufacturing process or contaminated raw materials. This is usually done through batch testing – checking a selection of products before release. It’s often referred to as QC or sterility checks. For cosmetics and personal care products, this testing requires Enumeration of Aerobic Mesophilic Bacteria and Yeasts & Moulds and Determining Absence of Specified Organisms. Preservative Efficacy Testing is carried out to determine that the preservative system of a product is working effectively. This test is carried out on products during the development stage. Finally, stability testing is carried out to determine what the shelf life of a product will be when released onto the market. It also determines if a product needs to be protected from any environmental conditions eg; daylight.

Parameters of cosmetic testing

  • Color
  • Odor
  • pH
  • Viscosity
  • Appearance
  • Package compatibility
  • Specific gravity

9. Disinfectant Testing :

Disinfectant tests are used to validate sanitizing agents for effectiveness against organisms, which is an increasing area of concern to manufacturers and regulatory agencies. Disinfectant efficacy must be established before a new disinfectant can be put on the market. Materials tested typically include household and industrial disinfectant agents, sporicides, fungicides, and hand sanitizers.

Tests for disinfectants

They are subdivided into suspension tests, carrier and surface disinfection tests and other practice-mimicking tests. The suspension tests comprise qualitative and quantitative suspension tests, and, as derived tests, the determination of the phenol coefficient and capacity tests.

10. Endotoxin Testing :

The Bacterial Endotoxin Test, or Lumulus Amebocyte Lysate (LAL) Test, quantifies endotoxins that are part of the cell wall of gram-negative bacteria. Performed as a lot release test, the Bacterial Endotoxin or LAL Test assesses medical devices coming in contact with cerebrospinal fluid or the cardiovascular system. Endotoxins (lipopolysaccharides, LPS) are agents of pathogenicity of Gram-negative bacteria, implicated in the development of Gram-negative shock. Endotoxin reacts with lipopolysaccharide-sensitive cells producing endogenous mediators such as tumour necrosis factor alpha (TNFα). E. coli, Salmonella, Shigella, Vibrio cholerae, and Neisseria meningitidis are some bacteria that produce endotoxins.

Three basic LAL methodologies have been developed: gel-clot, chromogenic and turbidimetric. The gel-clot technique can form the basis of a very simple detection method by adding the reagent to a sample in a test tube and incubating at 37oC for one hour.

11. Environmental Testing :

Environmental testing simulates the different climatic conditions and mechanical stress that products are exposed to during their lifetime. As a result, these tests expose weaknesses in a product’s design or performance that could occur in service, particularly at extreme levels.

Environmental testing is the measurement of the performance of equipment under specified environmental conditions, such as:

  • extremely high and low temperatures
  • large, swift variations in temperature
  • blown and settling sand and dust
  • salt spray and salt fog
  • very high or low humidity
  • wet environments, waterproofness, icing
  • presence of corrosive material
  • fungus, fluids susceptibility
  • vibrations (airborne and structural), gun fire
  • accelerations
  • solar radiation
  • high and low pressures (especially for aeronautical and space equipment)
  • operating at angles (especially for marine, aeronautical and space equipment)
  • electromagnetic interference (EMI), ESD, Lightning
  • acoustic measurements
  • power input variations

Micro-organisms in cosmetics may cause spoilage or chemical change in the product and can possibly harm cosmetic, health, beauty, and personal care product consumers. Cosmetics do not need to be sterile, but their preservative system must be able to take care of harmful microbial contamination.
For the
manufacturer of cosmetic and personal care products, it is important to ensure that their products are free of pathogenic microorganisms and are safe for consumer use.

 Required Testing for Micro Biology

  • Food
  • Water
  • Air

Microbiological Testing for Food

Middle East Testing Services LLC, accredited, full service analytical laboratory, specializes in microbiological analysis for the food, beverage and environmental industries. Microbiological analysis of food products is the use of biological, biochemical, molecular or chemical methods for the detection, identification or enumeration of microorganisms in a material (e.g. food, drink, environmental or clinical sample). It is often applied to disease causing and spoilage microorganisms. Microbiological sampling is conducted to test for pathogens in food products, this may be done in response to a complaint or to obtain further information about a premises (E.g. to determine temperature abuse, inadequate hand washing etc.

To ensure food safety and quality, food samples require certain microbiological tests considering following relevant points

Ø  The homogeneity of the food, the relative sizes of the sample to be taken.

Ø  The potential degree of variation of the parameters for analysis,

Ø  The significance and intended use of the analytical result.

  The microorganisms can be found in various foods & beverages and they can be harmful if they enter into a human body. Some of these microorganisms could prove to be resistant to one or more types of antibiotics.

Food testing is critical for ensuring food safety and quality. It helps in identifying harmful contaminants in food that can cause foodborne illnesses, allergies, or other health problems. In recent years, foodborne illnesses have become a significant public health concern globally. According to the World Health Organization (WHO), an estimated 600. 

Food testing helps in identifying the source of contamination and taking corrective measures to prevent the spread of the contamination. It also helps in ensuring that food products meet regulatory and industry standards. Food testing is essential for both the food industry and consumers. It helps in maintaining consumer trust in food products and ensuring that food products are safe for consumption.

In today’s world, food safety is becoming an increasing concern for people. This is often due to fear of spoilage or contamination of food items. Thus, it has become essential for businesses in the food industry to prioritize food safety and quality. This is needed to meet customer satisfaction and expectations.Food safety is an integral part of the production of all foods and the shared responsibility of all segments of the supply chain. In recent times there has been increased awareness for the need to evaluate the food safety practices in the production of agricultural products.


Listeria is a genus of bacteria that acts as an intracellular parasite in mammals. It is a Gram-positive, motile, facultative anaerobic pathogen that can be readily isolated from soil, water, and vegetation, including raw produce designated for human consumption without further processing.

Different species of Listeria are,

Listeria monocytogens

Listeria seeligeri

Listeria ivanovii

Listeria inoccua

It can contaminate many foods. People who eat those foods can get infected with Listeria. The infection is called listeriosis. Listeria are most likely to sicken people who are pregnant and their newborns, adults aged 65 or older, and people with weakened immune systems. L.monocytogenes can cause severe, life threatening infections. Pregnant women, newborn babies, the elderly and the immuno-compromised are particularly at risk. The infective dose for vulnerable individuals is not known, but could be very low (<100 CFU/g) in some cases. The incubation period is typically 30 days, but can vary from 1-90 days. Initial flu-like symptoms are often followed by vomiting and diarrhoea and in a few cases potentially fatal meningitis and septicemia may develop. Infection in pregnant women can lead to miscarriage and overall mortality rates of 30% are typical in outbreaks.

So it is necessary to detect and enumerate Listeria species from food items, to determine the level of contamination and take corrective action.

METS Laboratories, accredited, full service analytical laboratory, specializes in microbiological analysis for the food, beverage and environmental industries.

Enumeration of Listeria is carried out by standard methods like ISO, BAM etc…by using selective enrichment broth like BLEB , FRASER BROTH ..typical  colonies were isolated and enumerated.


Salmonella is a Gram negative rods genus belonging to the Enterobacteriaceae family. Within 2 species, Salmonella bongori and Salmonella enterica, over 2500 different serotypes or serovars have been identified. Salmonella Enteritidis, one of the most common serotypes of Salmonella reported worldwide.

Salmonella is a ubiquitous and hardy bacteria that can survive several weeks in a dry environment and several months in water. While all serotypes can cause disease in humans, a few are host-specific and can reside in only one or a few animal species:

 For example:

Salmonella enterica serotype Dublin in cattle and Salmonella enterica serotype Choleraesuis in pigs. When these particular serotypes cause disease in humans, it is often invasive and can be life-threatening. Most serotypes, however, are present in a wide range of hosts. Typically, such serotypes cause gastroenteritis, which is often uncomplicated and does not need treatment, but disease can be severe in the young, the elderly, and patients with weakened immunity. This group features Salmonella enterica serotype Enteritidis and Salmonella enterica serotype Typhimurium, the two most important serotypes of Salmonella transmitted from animals to humans in most parts of the world.

Disease caused by salmonella is,

Salmonellosis is a disease caused by the bacteria Salmonella. It is usually characterized by acute onset of fever, abdominal pain, diarrhoea, nausea and sometimes vomiting.

The onset of disease symptoms occurs 6–72 hours (usually 12–36 hours) after ingestion of Salmonella, and illness lasts 2–7 days.

Symptoms of salmonellosis are relatively mild and patients will make a recovery without specific treatment in most cases. However, in some cases, particularly in children and elderly patients, the associated dehydration can become severe and life-threatening.

Salmonella detection :

Rapid detection of the foodborne pathogen Salmonella in food processing is of crucial importance to prevent food outbreaks and to ensure consumer safety. Salmonella analysis done by using culture plate method on the basis of ISO standard.

Isolation of bacteria are based on cultures grown on differential agar media and subsequent colony counting. The basic steps for the detection of Salmonella in food include a pre-enrichment in buffered peptone water and an enrichment in selective media, followed by isolation on differential media and serological confirmation. Moreover, two to four days are required to obtain the initial results, and four to six additional days are necessary to confirm a positive result.

Bacillus cereus

Bacillus cereus is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. It is a toxin-producing facultatively anaerobic bacterium. The bacteria are commonly found in the environment and can contaminate food. It can quickly multiply at room temperature with an abundantly present preformed toxin.

Bacillus cereus is a foodborne pathogen that can produce toxins, causing two types of gastrointestinal illness: the emetic (vomiting) syndrome and the diarrhoeal syndrome. When the emetic toxin (cereulide) is produced in the food, vomiting occurs after ingestion of the contaminated food.

What Are the Types of Bacillus cereus?

There are two types of B. cereus. They affect different areas of your body:

Non-intestinal. This form affects other parts of your body. It can be found in plants, dust, soil, or water. Non-intestinal B. cereus can lead to even worse infections. Your risk continues to go up if you have this type alongside a weak immune system or other wounds or injuries from trauma or surgery.

Non-intestinal B. cereus tends to happen in your:

  • Respiratory system (the parts of the body that help you breathe)
  • Wounds
  • Eyes

Intestinal. This type affects your digestive system. It causes food poisoning. Usually, it can go away quickly on its own. But if you have a weak immune system, it can affect you more severely

What are the different types of intestinal Bacillus cereus?

There are two forms of intestinal B. cereus:

Enterotoxins (diarrheal syndrome). This type is the most common in the United States and Europe. With this version, your body makes the toxin in your small intestine after you’ve eaten food with the bacteria or spores (the cells they make). Food poisoning will usually show up 6 to 15 hours after you’ve eaten the food with the bacteria.

You might get this form of B. cereus from fish, meat, dairy, sauces, vegetables, soups, or stews.

Emetic (vomiting syndrome). With this form, the toxins are already in the food before you eat it. You’ll usually get sick between 1 and 6 hours after you consumed the food with the bacteria.

The most common food for this to happen in is rice. Not all rice has B. cereus. But it can form in it when cooked rice is unrefrigerated for too long. This illness can also happen with cheese and starchy foods like pastries, pasta, sushi, and potatoes.

What Are the Symptoms of Bacillus cereus?

The symptoms of food poisoning from B. cereus include:

  • Belly pain, watery diarrhea, and stomach cramping with enterotoxins
  • Nausea and vomiting with emetic syndrome

For non-intestinal B. cereus, the symptoms will be different based on the type of issue the bacteria creates in your body. The most severe complication is endophthalmitis, which is inflammation of the inner part of your eye. This creates the highest number of serious illnesses. You may even lose an eye with this complication. In some cases, it can be life-threatening.

The symptoms of this issue include:

  • Fever
  • Fatigue
  • Eye pain
  • Leukocytosis, or a high white blood cell count
  • Low vision
  • Red vision
  • A ring-shaped corneal ulcer.

Bacillus detection from food samples is very important to make a healthy community. It is mainly done on the basis of ISO standards. Mannitol egg yolk polymyxin agar and blood agar were used for the culturing of organism.


Enterobacteriaceae are a large family of Gram-negative bacteria that includes a number of pathogens such as KlebsiellaEnterobacterCitrobacterSalmonellaEscherichia coliShigellaProteusSerratia and other species.

Enterobacteriaceae family contains a large number of genera that are biochemically and genetically related to one another. This group of organisms includes several that cause primary infections of the human gastrointestinal tract. Members of this family are major causes of opportunistic infection (including septicemia, pneumonia, meningitis and urinary tract infections). Examples of genera that cause opportunistic infections are: Citrobacter, Enterobacter, Escherichia, Hafnia, Morganella, Providencia and Serratia.

Enterobacteriaceae are usually considered by food manufacturers as hygiene indicators and therefore used to monitor the effectiveness of implemented preventive pre-requisite measures such as Good Manufacturing Practices and Good Hygiene Practices (GMP/GHP).

Enterobacteriaceae are important zoonotic foodborne bacteria capable of endangering human health. A high ongoing prevalence and occasional outbreaks of these bacteria cause global morbidity and mortality, leading to huge economic losses. They are either motile or nonmotile and are non-spore-forming. Enterobacteriaceae can cause a wide range of illnesses, which include wound infections, urinary tract infections, gastroenteritis, meningitis, pneumonia, septicemia, and hemolytic uremic syndrome.

Some members of the Enterobacteriaceae have had a large impact on infectious diseases, clinical microbiology and public health. They are involved in diarrhoeal diseases and recognised as one of the major bacterial food-borne pathogens. Members of the Enterobacteriaceae are widely distributed. Although strains of some species are harmless commensals, such as some strains of E. coli, others are important human and animal pathogens, and some are pathogenic to plants and insects. Their ubiquitous distribution means that it is inevitable that some members of the Enterobacteriaceae will enter the food chain. Members of the family are responsible for causing foodborne disease and some also cause food spoilage and therefore contribute to substantial economical losses and food wastage.

ENTEROBACTERIACEAE can be detected and enumerated from food samples by using violet red bile glucose agar on the basis of standard method. According to colony characteristics and biochemical confirmation presence of Enterobacteriaceae is confirmed.

Clostridium perfringens

Clostridium perfringens is a Gram-positive, bacillus, anaerobic, spore-forming pathogenic bacterium of the genus Clostridium. C. perfringens is ever-present in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates, insects, and soil.

Common sources of C. perfringens infection include meat, poultry, gravies, and other foods cooked in large batches and held at an unsafe temperature. Outbreaks tend to happen in places that serve large groups of people, such as hospitals, school cafeterias, prisons, and nursing homes, and at events with catered food.

Under certain conditions, such as when food is kept at an unsafe temperature (between 40°F and 140°F), C. perfringens spores can transform into active bacteria, which multiply in the food. After someone eats food containing C. perfringens, it can produce a toxin (poison) that causes diarrhea. Clostridium perfringens is a common food poisoning causing bacteria. It causes diarrhea and stomach cramps

Clostridium normally grows at 44 °C, whereas some other clostridia are inhibited at this temperature. This property is used in ISO methods to give the medium more selectivity4. For detection of C. perfringens, mCP and TSC agar have been recommended. polymerase chain reaction (PCR) is one useful method for detecting Clostridium spp. in some samples such as food raw materials. Clostridium detection was performed using 16S rDNA-based PCR method with Clos 58 – f and Clos 780 – r primers.

Vibrio parahaemolyticus

V. parahaemolyticus is a curved, rod-shaped, Gram-negative bacterial species found in the sea and in estuaries. V. parahaemolyticus is oxidase positive, facultatively aerobic, and does not form spores. Like other members of the genus Vibrio, this species is motile, with a single, polar flagellum.

Vibrio parahaemolyticus infection can be acquired by eating raw or undercooked shellfish or drinking contaminated water. Eating raw oysters is the most common way the infection is spread as the organism naturally lives in the warm tidal waters where oysters grow. You also can get an infection if you have an open wound that comes in contact with raw or undercooked seafood, their juices, or their drippings. Vibrio parahaemolyticus is an intestinal infection that is characterized by lower gastrointestinal distress such as diarrhea and cramps. In some cases, nausea, vomiting, fever and headache may also be present.

Cases of Vibrio parahaemolyticus usually occur during the summer months, due to the fact that the organism can be found floating free in coastal waters and in fish and shellfish. During cooler months, the organism is commonly found in silt or mud on the bottom of marine environments.

V. parahaemolyticus was isolated more frequently from naturally contaminated seafood samples using the chromogenic agar than thiosulfate citrate bile salts sucrose agar medium, which is currently used for the isolation of V. parahaemolyticus.

To establish effective control measures to reduce the risk of V. parahaemolyticus infection and to ensure the safety of foods, efficient analytical methods for the detection of V. parahaemolyticus in foods and the environment must be available. Selective enrichment with alkaline peptone water (APW) or salt polymyxin broth (SPB) and plating of the enrichment culture onto thiosulfate citrate bile salts sucrose (TCBS) agar have been widely used for selective isolation of V. parahaemolyticus from foods.


Aflatoxins are various poisonous carcinogens and mutagens that are  produced by certain fungi that are found on agricultural crops such as maize (corn), peanuts, cottonseed, and tree nuts. The main fungi that produce aflatoxins are Aspergillus flavus and Aspergillus parasiticus, which are abundant in warm and humid regions of the world.

Large doses of aflatoxins can lead to acute poisoning (aflatoxicosis) and can be life threatening, usually through damage to the liver. Aflatoxins have also been shown to be genotoxic, meaning they can damage DNA and cause cancer in animal species. There is also evidence that they can cause liver cancer in humans. Aflatoxin-producing fungi can contaminate crops in the field, at harvest, and during storage.

Aflatoxins are a major source of disease outbreaks due to a lack of knowledge and consumption of contaminated food and feed worldwide. Excessive levels of aflatoxins in food of non-industrialized countries are of major concern.

Here are several different toxins in the aflatoxin group. They are designated aflatoxin B1 and aflatoxin B2 (because they appear blue under ultraviolet, or UV, light), aflatoxin G1 and G2 (because they appear green under UV light) and aflatoxin M1, which may be found in milk of cows fed aflatoxin-contaminated feed.

Toxicity and potency of aflatoxins make them the primary health hazard as well as responsible for losses associated with contaminations of processed foods and feeds. Determination of aflatoxins concentration in food stuff and feeds is thus very important.

The analytical methods for aflatoxin include thin layer chromatography (TLC), High performance liquid chromatography (HPLC), and enzyme-linked immunosorbent assay (ELISA). TLC has been most widely used method. Aflatoxins are extremely potent carcinogens in many animals.


Histamine is an organic nitrogenous compound involved in local immune responses, as well as regulating physiological function in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Histamine is involved in the inflammatory response and has a central role as a mediator of itching.

Lactic acid

Lactic acid is an alpha-hydroxy acid (AHA) due to the presence of carboxyl group adjacent to the hydroxyl group. It is used as a synthetic intermediate in many organic synthesis industries and in various biochemical industries. The conjugate base of lactic acid is called lactate.

Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common encapsulated, Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance.

Staphylococcus aureus

Staphylococcus aureus is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin.  It is capable of causing a wide range of infections such as endocarditis, food poisoning, cellulitis, toxic shock syndrome, skin and soft tissue infections, bone and joint infections, pneumonia and bloodstream infections.  This is because it has the ability to express multiple virulence factors and harbour multiple antibiotic resistance genes. S aureus strains may not always be resistant to antibiotics but they can acquire resistance. Cloxacillin is an antibiotic that has been used to treat infections caused by S. aureus and this has resulted in the emergence of methicillin-resistant Staphylococcus aureus (MRSA).  This pathogen can cause community- and healthcare-associated infections (HAIs).

Staphylococcal food poisoning is an acute intoxication that occurs when food contaminated with enterotoxin produced by this bacterium is consumed. Although precise data regarding the exact number of cases is lacking, staphylococcal food poisoning is considered to be among the most common causes of gastroenteritis worldwide. The presence of staphylococcal enterotoxin in food is usually due to cross contamination of ready to eat food with either raw food or, most likely, contamination from a food handler that is carrying Staphylococcus aureus.

Various types of foods serve as an optimum growth medium for S. aureus. Foods that have been frequently implicated in Staphylococcus food born disease(SFD) are meat and meat products, poultry and egg products, milk and dairy products, salads, bakery products, especially cream-filled pastries and cakes, and sandwich fillings.Foods implicated with SFD vary from country to country, particularly due to variation in consumption and food habits. If food is prepared in a central location and widely distributed, SFD outbreaks can have grave consequences impacting thousands of people.

The conventional S.aureus detection method is performed by the culture-based technique. On the basis of ISO standard method for the detection of S.aureus from food samples carried out by using Baired parker agar.

Vibrio cholerae

Vibrio cholerae is a Gram-negative, comma-shaped bacterium. The bacterium’s natural habitat is brackish or saltwater and attach themselves easily to the chitin-containing shells of crabs, shrimps, and other shellfish.

Vibrio cholerae is a non-spore forming, curved rod that is oxidase positive. It is very motile and has a single polar flagellum. The bacterium size is 1- 3 µm by 0.5-0.8 µm. It is a facultative anaerobe and is part of the Vibronaceae family. Serogroups O1 (classical and El Tor biotypes) and O139 are primarily responsible for cholera outbreaks. Pathogenic serogroups produce cholera toxin (CT) while non pathogenic strains may or may not produce this toxin. Recently, V. cholerae serogroup O75 strains possessing the cholera toxin gene were isolated from patients with severe diarrhea, and serogroup O141 has been associated with sporadic cholera-like diarrhea and bloodstream infections in the United States. Some serotypes may serve as a reservoir for the cholera toxin phage genome. Serotypes that do not produce cholera toxin can still cause illness in humans (i.e. enteritis).

Cholera is an acute diarrheal illness caused by infection of the intestine with Vibrio cholerae bacteria. People can get sick when they swallow food or water contaminated with cholera bacteria. The infection is often mild or without symptoms, but can sometimes be severe and life-threatening.

The cholera bacteria is passed through feces (poop). It is spread by eating or drinking food or water contaminated by the feces (poop) of an infected person. This occurs more often in underdeveloped countries lacking proper water supplies and sewage disposal.

The deadly effects of the disease are the result of a toxin the bacteria produces in the small intestine. The toxin causes the body to secrete enormous amounts of water, leading to diarrhea and a rapid loss of fluids and salts.

Alkaline saline peptone water is an enrichment broth used for the detection of Vibrio cholerae. Colony characteristics and salt tolerance are the major two factors used for the differentiation of V. cholerae from other vibrios.


Coliform’s count is a hygienic indicator and high level of coliform counts generally indicates unsanitary condition or poor hygiene practices during or after food production. It must be stressed that some members of coliforms are present as normal inhabitants in the environment, e.g., soil, vegetation and water.

Coliform bacteria are defined as either motile or non-motile Gram-negative non-spore forming bacilli that possess β-galactosidase to produce acids and gases under their optimal growth temperature of 35–37 °C. They can be aerobes or facultative aerobes.

Coliform bacteria include a large group of many types of bacteria that occur throughout the environment. They are common in soil and surface water and may even occur on your skin. Large numbers of certain kinds of coliform bacteria can also be found in waste from humans and animals. Most types of coliform bacteria are harmless to humans, but some can cause mild illnesses and a few can lead to serious waterborne diseases.

Coliform bacteria are often referred to as “indicator organisms” because they indicate the potential presence of disease-causing bacteria in water. The presence of coliform bacteria in water does not guarantee that drinking the water will cause an illness. Rather, their presence indicates that a contamination pathway exists between a source of bacteria (surface water, septic system, animal waste, etc.) and the water supply. Disease-causing bacteria may use this pathway to enter the water supply.

Specific types of coliform bacteria may be tested for, especially after a total coliform bacteria test is positive. These subgroups of coliform bacteria include fecal coliform and Escherichia coli or E. coli. Fecal coliform bacteria are specific to the intestinal tracts of warm-blooded animals, including humans, and thus require a more specific test for sewage or animal waste contamination. E. coli is a type of fecal coliform bacteria commonly found in the intestines of animals and humans. A positive E. coli result is much more serious than coliform bacteria alone because it indicates that human or animal waste is entering the water supply. There are hundreds of strains of E. coli. Although most strains are harmless and live in the intestines of healthy humans and animals, a few strains can produce a powerful toxin and can cause severe illness and death.

Water systems test for indicator organisms, like coliforms, to check for possible contamination by biological pathogens. Most coliforms are not harmful, but they come from the same sources as other bacteria and organisms that could make you sick.

VRBA is the suitable and specific medium used to detect and confirm the presence of coliforms from food samples.

Viable count

Viable count is a method used in cell culture to determine the number of living cells in a culture. This is different from other cell counting techniques because it makes a distinction between live and dead cells.


It is a genus of Gram-negative, non-spore-forming, facultatively anaerobic, rod-shaped bacteria from the family Enterobacteriaceae.

Mold & Yeast

Mold is a type of fungus that grows in multicellular filaments called hyphae. These tubular branches have multiple, genetically identical nuclei, yet form a single organism, known as a colony. In contrast, yeast is a type of fungus that grows as a single cell.

Microbiological Testing for Water

According to the World Health Organisation (WHO) more than 3.4 million people die each year from waterborne disease, most of whom are young children. In addition, it is estimated that around 50% of the population in developing countries is suffering from a water-related disease at any one time.

That makes infections contracted from contaminated water supplies a leading cause of illness and death worldwide and helps to explain why the provision of safe drinking water testing is such a high priority for governments and aid agencies.

Microbiological testing procedure uses samples of water and from these samples determines the concentration of bacteria. It is then possible to draw inferences about the suitability of the water for use from these concentrations. This process is used, for example, to routinely confirm that water is safe for human consumption or that bathing and recreational waters are safe to use.

Heterotrophic plate count

Heterotrophic plate count (HPC) is a method that measures colony formation on culture media of heterotrophic bacteria in drinking water. Thus, the HPC test (also known as Standard Plate Count) can be used to measure the overall bacteriological quality of drinking water in public, semi-public and private water systems.


Coliform bacteria are a large group of bacteria that are found in very high concentrations in the fecal matter of warm-blooded animals such as dogs, deer, and humans.  Some coliform bacteria can cause disease in humans, but most do not.  But when any coliform bacteria are detected in a water supply it is a clear indication that the water has been contaminated with animal fecal matter.  Fecal matter may contain other, much more dangerous organisms.  So, coliform bacteria are classified as an indicator organism.  The presence or absence of coliform bacteria suggests the presence or absence of more dangerous disease-causing agents in the water.

Faecal Coliform

A faecal coliform is a facultatively anaerobic, rod-shaped, gram-negative, non-sporulating bacterium. Coliform bacteria generally originate in the intestines of warm-blooded animals.


The genus Legionella is a pathogenic group of Gram-negative bacteria that includes the species L. pneumophila, causing legionellosis (all illnesses caused by Legionella) including a pneumonia-type illness called Legionnaires’ disease and a mild flu-like illness called Pontiac fever.

pseudomonas aeruginosa

Pseudomonas aeruginosa is a common encapsulated, Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance.

Faecal streptococci

Faecal streptococci. Like coli bacteria, streptococci are present in human and animal intestines, but also in the stomach. Many species of streptococcus are pathogenic. They cause diseases such as bacterial pneumonia, ear infection and bacterial meningitis.

Escherichia coli

Escherichia coli (E. coli) is a bacterium commonly found in the gut of warm-blooded organisms. Most strains of E. coli are not harmful but are part of the healthful bacterial flora in the human gut. However, some types can cause illness in humans, including diarrhoea, abdominal pain, fever, and sometimes vomiting.

Escherichia coli is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms. Escherichia coli (E. coli) is a bacterium that is commonly found in the gut of humans and warm-blooded animals. Most strains of E. coli are harmless. Some strains however, such as Shiga toxin-producing E. coli (STEC), can cause severe foodborne disease. It is transmitted to humans primarily through consumption of contaminated foods, such as raw or undercooked ground meat products, raw milk, and contaminated raw vegetables and sprouts.

An E. coli infection is any illness you get from strains of E.coli bacteria. For instance, there are harmful strains of E.coli that cause watery diarrhea, stomach pain and other digestive symptoms gastroenteritis if you accidentally ingest them. These are sometimes called diarrheagenic E.coli and they’re often what people mean when they talk about E.coli infections. But the E.coli that usually live in your gut can also get in places they’re not supposed to be (like your urinary tract). This causes an E.coli infection there.

E.coli can be contagious (spread from person to person). While you don’t get it from sneezing or coughing, you can get it from caring for someone with an E.coli infection, especially if you come in contact with their poop. You can also get it from objects, surfaces or food someone with an E.coli infection has touched if they don’t wash their hands well enough.

Health department evaluation of all diagnosed E. coli infections in food workers is mandatory before they may return to work. If symptoms include diarrhea or vomiting, exclude food employee from food establishment, Must be symptom free for at least 24 hours before returning to work.

Eosine  methylene blue (EMB) is a selective medium for the detection of E.coli from food samples. On the basis biochemical confirmation and colony characteristics presence of E.coli confirmed.

Legionella water

Legionella bacteria is commonly found in water. The bacteria are dormant below 20°C and do not survive above 60°C. Legionnaires disease is a potentially fatal type of pneumonia, contracted by inhaling airborne water droplets containing viable Legionella bacteria.


Endotoxin is a type of pyrogen and is a component of the exterior cell wall of Gram-negative bacteria, like E. coli. Endotoxin is a lipopolysaccharide or LPS. LPS consists of the lipid A portion containing fatty acids and disaccharide phosphates, core polysaccharides and the O-antigen.

Microbiological Testing for Air

The most important sources of contamination in any specific manufacturing operation and they will probably come up with people, raw materials and water as the top three. This is a perfectly reasonable response, but there is one other factor that is always present and that is air. Viable microorganisms can be found in the atmosphere almost anywhere – bacterial spores can be isolated from the jet stream several miles above the Earth’s surface – but the microbiology of the air is sometimes overlooked.

Viable count

Viable count is a method used in cell culture to determine the number of living cells in a culture. This is different from other cell counting techniques because it makes a distinction between live and dead cells.

Mould & Yeast

Mould is a type of fungus that grows in multicellular filaments called hyphae. These tubular branches have multiple, genetically identical nuclei, yet form a single organism, known as a colony. In contrast, yeast is a type of fungus that grows as a single cel