Lecture 20 Flashcards
What is the classification of Enterococci/Faecal Streptococci, and what are some examples?
Enterococci/Faecal Streptococci are members of the genera Streptococcus and Enterococcus within the Family Streptococcaceae.
They are catalase-negative, coagulase-negative bacteria.
In 1984, Enterococci were separated from Streptococci and given formal genus status due to a more distant relationship. Enterococcus faecalis (mainly human, also animal)
Enterococcus faecium (important in clinical, food, and water microbiology)
Other species: Enterococcus avium (birds, poultry), Enterococcus durans (swine), Enterococcus casseliflavus (animal), Enterococcus gallinarum (animal).
What are the sources of Enterococci/Faecal Streptococci?
Found primarily in the intestinal tract of humans, animals, birds, and poultry.
More numerous in animal faeces than in human faeces.
Enterococcus faecalis is predominant in human intestines, while E. faecium is more common in animal faeces.
Also found in various environments (plants, soil, dust) due to dissemination in animal excrement.
What are the characteristics and pathogenicity of Enterococci/Faecal Streptococci?
Characteristics:
Gram-positive, ovoid cocci
Non-motile, non-spore-forming
Catalase-negative, facultative anaerobes
Bile and salt tolerant, ferments lactose with acid production
More resistant to environmental stresses than coliforms
Pathogenicity:
Prominent nosocomial pathogens
Infections include urinary tract infections (UTIs) and endocarditis
Concern due to multiple antibiotic resistance
How are Enterococci/Faecal Streptococci used as indicator organisms in water and food
Use as Indicators in Water:
Presence indicates faecal contamination from warm-blooded animals.
Absence suggests no such contamination.
Act as secondary faecal indicators, confirming faecal pollution in doubtful cases.
They are more reliable for detecting viruses than coliforms.
Rarely multiply in polluted water, making them better indicators for swimming pools than coliforms.
Use as Indicators in Food:
Presence indicates exposure to conditions that may allow undesirable microbial growth.
Better indicators for frozen foods than coliforms.
More persistent in water and shellfish than coliforms.
Can multiply in food processing plants, indicating poor hygiene.
What are what are the limitations of Enterococci/Faecal Streptococci
Their high resistance to environmental conditions makes them somewhat unreliable as general indicators of faecal pollution.
Alone, faecal streptococci counts provide little information. Total viable counts or coliform/E. coli counts are needed for more accurate analysis.
