Corynebacterium Flashcards
Also known as the diphtheria bacillus or Kleb-Loffler bacillus
C. diph
It is not part of the indigenous microbiota of the respiratory tract,
and only inhabits the human nasopharynx in a carrier state
o carrier state – harbors the bacteria but asymptomatic
C.diph
It rarely enters the bloodstream
C.diph
It is readily killed by heat and by most usual disinfectants
• It is a glucose and maltose fermenter
C.diph
Preferred medium: Regular culture media enriched with
serum, cysteine, and potassium tellurite
C.diphth
Its cells have rounded ends and “club-shaped sweiings”
o Its highly pleomorphic cells are arranged in pairs and
create X, V, Y and L formations that closely resembles
Chinese letters
C,diph
Biochemical tests: (-) Urease, (+) nitrate reduction
C.diph
Best specimens: Nasopharyngeal and throat swabs
C.diph
Toxin: It favors an alkaline pH (7.8-8.0), an aerobic
environment, and sufficient amount of iron in the
medium consumed
Diph toxin
It causes tissue necrosis and exudate formations over
the tonsils, larynx and pharynx
C.diph: diph toxin
t is an acute, infectious disease that is characterized by
the production of a systemic toxin and a false membrane
lining of the throat mucous membrane that may
eventually lead to respiratory obstruction
Respiratory diphtheria
o Non-healing ulcers with dirty gray membrane
o Infection of the skin/non-respiratory sites
• Cutaneous or skin diphtheria (Veldt sore)
Systemic infection affecting various organs
▪ Demyelinating peripheral neuritis
▪ Cardiac failure Systemic infection affecting various organs
▪ Demyelinating peripheral neuritis
▪ Cardiac failure
Cutaneous or skin diphtheria (Veldt sore)
• It is one of the most frequently isolated and most clinically
significant Corynebacteria species
C. urea
It is a urinary pathogen, a strict aerobe, and lipophilic
C.urea
It does not ferment glucose and maltose
C.urea
Microscopy: Arranged in V-shaped forms and palisades
C.urea
Culture: BAP - Colonies are pinpoint, white, smooth, and are
non-hemolytic
C.urea
Biochemical test: Rapid urease producer
C.urea
It is an indigenous microbiota of the human nasopharynx
o indigenous microbiota
▪ normal inhabitants but limited population
▪ not easy to isolate
C.pseudo
It causes respiratory infection, UTI, and cutaneous wound
infections in immunocompromised patient, such as those who
have AIDS
C.pseudo
Microscopy: Cells are arranged in parallel rows or palisades
and do not exhibit any other characteristic “pleomorphism” that
is similar to other corynebacteria
C.pseudo
Biochemical test: (+) Urease and nitrate production
C.pseudo
It is a skin microbiota that is found in inguinal, axillary, and rectal
sites
Corynebacterium jeikeium
It is an obligate aerobe and a multi-antibiotic resistant bacterium
C.jeikye
It is isolated from immunocompromised individuals
C.jeik
It is a common cause of diphtheroid prosthetic valve
endocarditis in adults
C.jeik
Microscopy: Pleomorphic, club-shaped, and arranged in V-
shaped forms
C.jeik
BAP - Colonies appear large when added with 1%
Tween 80
C.jeik
Biochemical test: (-) Urease and nitrate reduction.
C.jeik
It is acquired through animal contact or ingestion of
unpasteurized dairy products
C.ulcer
It is also isolated from skin ulcers and exudative pharyngitis
C.ulcer
• It is associated with diphtheria-like sore throats since a
significant isolates have shown to produce a diphtheria-like
toxin
C.ulcer
BAP - Colonies have a narrow zone of Beta hemolysis
o CTBA (Cysteine-Tellurite Blood Agar) - Colonies have a
surrounding brown halo
o Loeffler’s serum agar - Colonies exhibit growth
C.ulcer
Biochemical test: (+) Urease and gelatinases, (-) nitrate
reduction
C.ulcer
It produces a dermonecrotic toxin that causes death of
various cell types
C.pseudotuberculosis
CTBA - Colonies exhibit a black color and are
surrounded with a brown halo
o BAP - Colonies are small and yellowish-white
C.pseudotuberculosis
Biochemical test: (+) Urease (-) gelatinase
C.pseudotuberculosis
Methylene blue staining: Bacterial cells exhibit a
beaded formation
C.diph
are used for staining
metachromatic granule
Neisser’s and Albert’s stains
staining method is composed mainly
of either methylene blue or crystal violet
Neisser’s staining
stain is composed of malachite green
and toluidine
Albert’s stain
It is the preferred medium for the isolation and
identification of corynebacteria
Cytine tellutite blood agar (CTBA)
The multiplication of corynebacteria occurs
within the range of what degree celsius?
15°C to 40°C
+) Result: Colonies of corynebacteria exhibit a
black or brown color after 48 hrs of incubation
CTB
It contains sheep blood, bovine serum, cysteine,
and potassium tellurite
CTBA
It is composed of sheep blood, cysteine,
potassium tellurite, and sodium thiosulfate
Tindsdale agar
gram-positive and urease negative with brown halo
C. diphtheriae
It is useful for observing the microscopic
morphology and metachromatic granules of C.
diphtheriae
Loeffler’s serum agar
▪ (+) Result: C. diphtheriae colonies exhibit a
“poached-egg” appearance
o Loeffler’s serum agar
The metachromatic granules of C. diphtheriae
are called
“Babes-Ernst” bodies
This is used to observe the urease production of
C. uralyticum
Christensen urea slant
In vitro diphtheria toxin detection using
immunodiffusion
Elek’s Test
Precipitin lines are observed
- slant lines found in the junction where the
growth of inoculum and filter paper meet
Elek’s Test
All staph are Aerobic or facultative anaerobic except for
S. saccharolyticus
