5 Coliform Bacteria Examples :Detailed Explanations

Coli form bacteria are the gram negative, rod shaped structures.

Coli form bacteria are gram negative, rod shaped organisms. They can be motile or non-motile forms. They can be known as indicator organisms.

Coliform Bacteria Examples:

Escherichia coli:

E.coli comes under fecal coli form bacteria. E.coli is generally present in warm blooded animals and reproduce rapidly in such conditions.

E.coli is gram negative, rod shaped, facultative anaerobic bacteria. The some species of E.coli are generally non- pathogenic and found in intestine of humans and animals. The non-pathogenic strains assist the host in the production of vitamins like K2.

E.coli can cause diseases in case of food poising and sometimes can cause urinary tract infections (UTI). E.coli commonly come out of the body through the faecal matter.

These species help in the detection of water purity. If water contain the Escherichia species we can say that the water is contaminated with the faecal matter or sewage water.


Citrobacter species are gram negative coli form bacteria. They come under Enterobacteriaceae family.

The citrobacter species like C.  amalonaticus, C. koseri and C. freundii are the most common types of coliform bacteria.

The species of citrobacter are divided basing on the ability of converting tryptophan into indole, fermentation of lactose and usage of malonate.

Thses are generally non-pathogenic bacteria but occassionally can cause infecions.

They may cause infections like neonatal sepsis, urinary tract infections and meningitis. Occasionally they may cause pneumonia.

coliform bacteria examples
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Enterobacter is a gram negative, bacilli form and facultative anaerobic bacteria. These species come under the family of entero-bactericeae.The enterobacter species generally present on the skin, gastrointestinal tract, water, soil, some food products.

There are several species of enterobacter among them some species are pathogenic and cause generally infections like nosocomial infections but rarely cause infections like urinary tract infections, soft tissue infections, endocarditis, osteomyelitis and respiratory infections. The common species of enterobacter are enterobacter cloacae and enterobacter aero-genes.


Hafnia is a gram negative, facultative anaerobic, bacilli. These speceis come under the family of hafniaceae.

There are some species of hafnia group among them H.alvei is the normal flora of humans. This is commonly found in the gastrointestinal tract of humans and can act as a probiotic. H.alvei is used in dairy products in fermentation process. This is commonly non-pathogenic but sometimes may cause diarrhea, meningitis, urinary tract infections, wound infections, intra-abdominal infections.


Klebsiella is a gram negative, aerobic and rod shaped bacterium. These organisms generally referred as normal flora of humans as they present in the intestine of humans and they are non- pathogenic in nature.

There are some Klebsiella species like Klebsiella pneumonia and Klebsiella oxytoca can cause infections in humans like pneumonia, meningitis. Usually these are transmitted through person to person in contact.


Serratia is a gram negative, facultative anaerobic, bacilli form bacteria. The moist environment, phosphorous and fatty rich environment is suitable for the growth of this bacteria. It can grow even on soaps and toilet area. It is generally non-pathogenic but occasionally may cause infections like urinary tract infections, endocarditis, respiratory tract infections and ocular lens infections.


Yersinia is a gram negative, facultative anaerobic bacteria. These are pathogenic organisms. It can cause acute diarrhea, sepsis and pseudo appendicitis.

It may be transmitted not only through the raw food items, unprocessed food items like raw meat but also through the contaminated water and unpasteurized milk.

Types of Coliform Bacteria:

There are three types of coli form bacteria in nature.

Total coli form Bacteria:

This class of coli form bacteria includes all the species of coli form bacteria in the nature.

Fecal coli form Bacteria:

This is sub- class of total coli form bacteria. This class of species are abundantly found not only in the intestine and fecal matter of humans but also in pigs, cow, dogs. These organism are non pathogenic and pathogenic in nature.

The presence of fecal coli form bacteria indicates the contamination of water with fecal matter.


E.coli is the sub class of fecal coli form bacteria, this is the best indicator of coli form bacteria in water contamination. This is abundantly found in the intestine of warm blooded animals and comes out through the fecal matter.

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Frequently Asked Questions:

What is Osteomyelitis?

The osteomyelitis is a bone infection caused by the pathogenic bacteria like streptococcus bacteria and serratia. An osteomyelitis can cause pain, swelling and redness in the affected area.

What is an indicator test for coliform bacteria?

The presence of coliform bacteria is indicated by the membrane test and filtration technique.

In membrane bound test the cellulose ester membrane and agar are used. After incubation period the blue color can be observed this indicates the presence of Beta-Glucuronidase enzyme of E.coli. This enzyme breakdowns the Indoxyl-beta glucuronide which is present in MI- agar medium.

Narne Naga Srilakshmi

Hi...I am Nagasrilakshmi Narne, a postgraduate in Biotechnology and English. also completed my B.Ed. I worked in Vimtalabs as a project trainee and I have work experience as a faculty of English. So I can explain topics in simple language. Let's connect through LinkedIn:https://www.linkedin.com/in/narne-naga-srilakshmi-55069334

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