Enterococci ppt mahadi

Sharq Elneil College
School of Medical Laboratory Sciences
Department of Microbiology
Medical Bacteriology course

Enterococci
Dr.Mahadi Hassan Mahmoud
mahadi2010sd@yahoo.com
Bsc, Msc, MIBMS Microbiology

The Natural habitat
Normal components of the flora of:
 Intestinal tract
 Oral cavity
 Vaginal canal of humans and
animals

Morphology
 Gram-positive cocci (0.5 and
1.25 micrometers in diameter)

usually occur in pairs or short
chains
Non-capsulate
Non-motile.

General properties:
production of gas from glucose
(most enterococci are negative)
Have ability to grow at both
45°C and 10°C temperatures).
Can grow on media containing
Bile aesculin,

Medically Important species

At least 12 different species have
been associated with various illnesses

Enterococcus faecalis and E.
faecium — have emerged as a major
cause of nosocomial infections

Culture &chaacteristics:
Enterococci are aerobic organisms
capable of growing over a wide
temperature range,
10–45 ºC
On blood agar,
Enterococci are mainly nonhaemolytic
but some strains show alpha or beta-
haemolysis

ON MacConkey &CLED

Ferments lactose, producing small dark-
red magenta colonies on MacConkey aga

small yellow colonies on CLED (cysteine
lactose electrolyte-deficient) agar

Enterococcus species are also
able to grow in the presence of 6.5%
sodium chloride and 40% bile.

 When grown on media containing
aesculin, enterococci hydrolyze the
aesculin, producing black colonies.

Virulence Factor

 Polysaccharides on the surface of
enterococci represent an effective way to
prevent phagocytosis.
 Secreted factors (cytolysin/hemolysin,
gelatinase and serine protease)
 cell surface-located proteins or
adhesins (Esp) and the adhesin of
collagen Adhesins (Acm and SagA)

Pathogeicity:
Enterococcus faecalis, causing about 95% of
enterococcal infections including infections
of the

Urinary tract infection

 Biliary tract,ulcers (e.g. bed sores)

 Wounds (particularly abdominal)

 Occasionally endocarditis or meningitis

Laboratory diagnosis
specimens:
Collection of Spacimen
Direct Exam
Culture
Identificaion
Serology
Molecular characterization

Biochemical Tests
Catalase negative
Ferment lactose (also
mannitol and other sugars).
Hydrolyze aesculin
Reduce litmus milk

grow on reduce sorbitol glycerol, D- L- melibios
0.4% tetrazol tagatose arabinos e
telluride ium to e
formaz
an

E. yes Yes Acid Acid Acid No Acid No Acid
faecalis
E. No No No Acid No Acid No Acid Acid Acid
faecium

Lancefield Grouping
Enterococci possess Lancefield
Group D antigen (as also some
streptococci).
The Group D antigen of enterococci
is unlike that of other Lancefield
groups.
It is not extracted by traditional acid
extraction techniques. Enzyme
techniquesbased on Maxted’s enzyme
are required.

Antibiotic Resistant
Most enterococci are susceptible to
ampicillin and resistant to
cephalosporins.

Resistance is shown against
penicillin. Vancomycinand ampicillin
resistance appear to be
emerging,associated particularly with
hospital infections.

Penicillin or Ampicillin
Vancomycin
For urine isolates
Fluoroquinolones
Nitrofurantoin
Fosfomycin
Vancomycin-resistant strains
(VRE)

Enterococci ppt mahadi

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