Coliform Bacteria Overview

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Questions and Answers

Which species of Bifidobacterium was identified as most representative in a highly contaminated stream near Bologna, Italy?

B.animalis

B.angulatum

B.breve

B.adolescentis (correct)

What common issue arises when attempting to isolate bifidobacteria from environmental waters?

High contamination from other bacteria (correct)

Formation of toxic byproducts

Complete absence of bifidobacteria

High recovery percentages

What is a characteristic feature of Clostridia in terms of their reaction to oxygen?

They are strictly aerobic

Most species are obligate anaerobes (correct)

They thrive in high-oxygen environments

They are facultative anaerobes

What type of bacteria is included in the genus Clostridium?

Gram-positive rods Signup and view all the answers

Which of the following species is NOT typically associated with Bifidobacterium?

C.perfringens Signup and view all the answers

What is the primary role of Clostridia in the environment?

Degrading organic material to acids and alcohols Signup and view all the answers

Which statement accurately describes the survival capabilities of Clostridia?

They can resist dryness, heat, and aerobic conditions Signup and view all the answers

Which of the following statements about the isolation of bifidobacteria is true?

False positives are common in the isolation process Signup and view all the answers

Which of the following characteristics is true of total coliforms?

They ferment lactose with gas production at 35–37 °C. Signup and view all the answers

What is the traditional temperature at which fecal coliforms are defined to ferment lactose?

44.5 °C Signup and view all the answers

Which of the following genera is NOT included in the total coliform definition?

Pseudomonas Signup and view all the answers

What is a limitation of the multiple-tube fermentation technique for testing coliforms?

It requires several days to complete. Signup and view all the answers

Which coliform species is commonly detected in environmental polluted waters?

Klebsiella pneumoniae Signup and view all the answers

What is the key difference between total coliforms and fecal coliforms?

Fecal coliforms are a subset of total coliforms that ferment lactose at a specific higher temperature. Signup and view all the answers

What does the Voges–Proskauer reaction test for in coliform differentiation?

Presence of acetoin Signup and view all the answers

Which detection method is more sensitive for estimating low levels of contamination in water samples?

Filtration through membrane Signup and view all the answers

What types of salmonellosis can be caused by Salmonella pathogenic to humans?

Typhoid and paratyphoid fever Signup and view all the answers

Which species of Salmonella is primarily pathogenic only to humans?

Salmonella typhi Signup and view all the answers

What is the primary mode of transmission for typhoid fever?

Water and food contaminated with feces Signup and view all the answers

Which serovar of Salmonella is known to frequently cause gastroenteritis in humans?

Salmonella enteritidis Signup and view all the answers

What is the minimal infective dose of Salmonella that can cause clinical symptoms?

Less than 1,000 cells Signup and view all the answers

Which serovar causes fowl typhoid and is mainly isolated from birds?

Salmonella gallinarum Signup and view all the answers

In pediatric settings, how is salmonellosis typically transmitted?

Hands of medical staff Signup and view all the answers

Which of the following options is NOT associated with Salmonella paratyphi?

Causes gastroenteritis in animals Signup and view all the answers

Study Notes

Coliforms

Coliforms are a group of bacteria that are gram-negative, oxidase-negative, non-sporeforming rods, that ferment lactose with gas production at 35–37 °C, after 48h, in a medium with bile salts and detergents.
Coliforms are classified as a group due to their similar biochemical properties, but these properties can vary within the group.
When carrying out coliform testing of environmental waters, several species of the four Enterobacteriaceae genera Escherichia, Klebsiella, Enterobacter, and Citrobacter give positive results
The environmental significance of said species is not uniform, meaning counting coliforms does not necessarily equate to fecal pollution.
Fecal coliforms (or thermotolerant coliforms) are coliforms that ferment lactose at 44.5 °C in a medium with bile salts.
The range of species detected by the experimental procedure is much lower than that of total coliforms.
Traditional tests for total and fecal coliforms are carried out either by the multiple-tube fermentation technique or by filtration through membrane.
The multiple-tube fermentation technique is used for medium or highly contaminated waters, and filtration through a membrane is used for low or very low contaminated waters.
Filtration through membrane is a very sensitive technique since it can detect one (culturable) cell in 500 or even 1,000 mL of water.
Both methods take several days to complete and do not detect viable but non-culturable bacteria.
The limitations of these methods have led to the discovery of alternative methods, faster and, if possible, less prone to false negative results such as those caused by the viable but non-culturable bacteria.

Bifidobacterium

Identification of Bifidobacterium species in polluted water can, in principle, provide information on the origin of fecal pollution.
Bifidobacteria are the less studied of all fecal bacteria, due to the technical difficulties in their isolation and cultivation.
Other Gram-positive bacteria, such as Streptococcus and Lactobacillus, can inhibit the growth of Bifidobacterium.
Although selective media has been designed for the isolation of bifidobacteria from environmental waters, the outcome is still unsatisfactory, with appreciable numbers of false positives and low recovery percentages.

Clostridia

The genus Clostridium is one of the largest genera of the prokaryotes containing 168 validly published species.
Clostridia are Gram-positive rods, forming endospores.
Most of the clostridial species are motile with peritrichous flagellation.
Cells are catalase-negative and do not carry out a dissimilatory sulphate reduction.
Clostridia usually produce mixtures of organic acids and alcohols from carbohydrates and proteins.
The genus Clostridium includes psychrophilic, mesophilic, and thermophilic species.
The major role of these organisms in nature is in the degradation of organic material to acids, alcohols, CO2, H2, and minerals.
Frequently, a butyric acid smell is associated with the proliferation of clostridia.
The ability to form spores that resist dryness, heat, and aerobic conditions makes the clostridia ubiquitous.
Most species are obligate anaerobic, although tolerance to oxygen occurs.
Oxygen sensitivity restricts the habitat of the clostridia to anaerobic areas or areas with low oxygen tensions.

Salmonella

Salmonellae pathogenic to humans can cause two types of salmonellosis: typhoid and paratyphoid fever (do not confuse with typhus, a disease caused by a rickettsia); gastroenteritis.
Salmonellae pathogenic to humans can cause two types of salmonellosis: typhoid and paratyphoid fever (do not confuse with typhus, a disease caused by a rickettsia); gastroenteritis.
Low infective doses (less than 1,000 cells) are sufficient to cause clinical symptoms.
Salmonellosis of newborns and infants presents diverse clinical symptoms, from a grave typhoid-like illness with septicemia to a mild or asymptomatic infection.
In pediatric wards, the infection is usually transmitted by the hands of staff.

Salmonella - Taxonomy and Nomenclature

Salmonella is a genus of bacteria containing 2,600 serovars.
The classification of Salmonella is complex and under constant revision.
There are four main serovars: Salmonella enterica, Salmonella bongori, Salmonella subterranea, and Salmonella diarizonae.
Salmonella enterica is responsible for most human salmonellosis.
Most infections involving Salmonella enterica subsp. enterica are due to serovars that are pathogenic to both humans and animals.
Salmonella enterica subsp. enterica serovars are found in a wide variety of hosts, including poultry, cattle, pigs, and humans.
Salmonella enterica subsp. enterica can cause a wide range of infections, including gastroenteritis, typhoid fever, and paratyphoid fever.
The serovars Enteritidis and Typhimurium cause the most cases of gastroenteritis.
The serovars Paratyphi A, Paratyphi B, and Paratyphi C cause typhoid and paratyphoid fever.
Salmonella Typhi is the only serovar that causes typhoid fever, and it is often transmitted by contaminated water and food.
The serovars Gallinarum causes fowl typhoid, a disease that mainly affects chickens.
The serovar Abortusovis is pathogenic to sheep.
The serovar Typhisuis is pathogenic to swine.

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Description

This quiz covers key aspects of coliform bacteria, including their classification, biochemical properties, and significance in environmental testing. It explores both total and fecal coliforms and their implications in assessing water quality. Test your understanding of these important microorganisms and their roles.