Gram Positive Bacilli, non- encapsulated, non-motile, non-spore forming Flashcards
Majority of the species are found as indigenous microbiota on the skin and mucous membranes
of humans and animals
Corynebacterium
corynebacterium species are glucose and maltose fermenters except
C. urealyticum and C.
pseudodiphtheriticum
Slightly curved, gram-positive rods with unparallel sides and slightly wider ends that
produce a ―club-like shape
Corynebacterium
BAP-colonies have a small zone of Beta hemolysis, although some strains nonhemolytic
Corynebacterium
The members of this group are fastidious corynebacteria that require 48 hours of
incubation before any growth can be observed
The addition of lipids in the culture medium can enhance the bacterial growth
. Lypophilic corynebacteria
Examples of lipophilic corynebacteria
Corynebacterium jeikeium and C. urealyticum
The members of this group exhibit fermentative or oxidative metabolism
. Non-lipophilic corynebacteria
examples of non-lipophilic corynebacteria
: C. diphtheria, C.pseudodiphtheriticum, C. pseudotuberculosis,C.
ulcerans
o Corynebacterium species that are associated with human infections and diseases.
: C. diphtheria, C. jeikenum, C. pseudotuberculosis,
C.pseudodiphtheriticum, and C. urealyticum
It is also known as the diphtheria bacillus or Kleb-Loffler bacillus
Corynebacterium diphtheria
It is a non-lypophilic, facultative anaerobe but grows best under aerobic conditions
It is not part of the indigenous microbiota of the respiratory tract, and only inhabits the human
nasopharynx in a carrier state
Corynebacterium diphtheria
It is acquired through inhalations of contaminated respiratory droplets or direct contact with
infected cutaneous lesion
Corynebacterium diphtheria
it rarely enters the bloodstream
Corynebacterium diphtheria
It is a glucose and maltose fermenter
Corynebacterium diphtheria
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
Corynebacterium diphtheria
Corynebacterium diphtheria biochemical test
(-) Urease (+)nitrate reduction
Three biotypes of Corynebacterium diphteriae:
very small, flat, dry, and grayish-black colonies; non-hemolytic
Intermedius
Three biotypes of Corynebacterium diphteriae:
small, black, and covex colonies that have a ―”fried-egg” appearance; hemolytic
mitis
Three biotypes of Corynebacterium diphteriae:
large, flat, and dark gray colonies that have a ―”daisy-head” appearance; nonhemolytic
Gravis
o It is a heat-labile polypeptide
o It is produced by strains with a lysogenic beta-phage that carries the TOX gene
Diphtheria Toxin
It causes tissue necrosis and exudate formations over the tonsils, larynx and pharynx
Diphtheria Toxin
It favors an alkaline pH (7.8-8.0), an aerobic environment, and sufficient amount of iron
in the medium consumed
Diphtheria Toxin
the toxin is absorbed systemically but is less severe
. Cutaneous or skin diphtheria (Veldt sore)- C. diptheria
It is one of the most frequently isolated and most clinically significant Corynebacteria species
Corynebacterium urealyticum
It is a urinary pathogen, a strict aerobe, and lipophilic
Corynebacterium urealyticum
It does not ferment glucose and maltose
Corynebacterium urealyticum
Arranged in V-shaped forms and palisades
Corynebacterium urealyticum
: BAP- Colonies are pinpoint, white, smooth, and are non-hemolytic
Corynebacterium urealyticum
Biochemical test: Rapid urease producer
Corynebacterium urealyticum
(Hoffman bacillus)
Corynebacterium pseudodiptheriticum
It is an indigenous microbiota of the human nasopharynx
Corynebacterium pseudodiptheriticum
It causes respiratory infection, UTI, and cutaneous wound infections in immunocompromised
patient, such as those who have AIDS
Corynebacterium pseudodiptheriticum
Cells are arranged in parallel rows or palisades and do not exhibit any other
characteristic ―pleomorphism‖ that is similar to other corynebacteria
Corynebacterium pseudodiptheriticum (Hoffman bacillus)
(+) Urease and nitrate production
Corynebacterium pseudodiptheriticum (Hoffman bacillus)
It is a skin microbiota that is found in inguinal, axillary, and rectal sites
Corynebacterium jeikenum
It is an obligate aerobe and a multi-antibiotic resistant bacterium
Corynebacterium jeikenum
It is isolated from immunocompromised individuals
Corynebacterium jeikenum
It is a coomon cause of diphtheroid prosthetic valve endocarditis in adults
Corynebacterium jeikenum
Microscopy: Pleopmorphic, club-shaped, and arranged in V-shaped forms
Corynebacterium jeikenum
BAP- Colonies appear large when added with 1% Tween 80
Corynebacterium jeikeium
(-) Urease and nitrate reduction.
Corynebacterium jeikenum
It is acquired through animal contact or ingestion of unpasteurized dairy products
It is also isolated from skin ulcers and exudative pharyngitis
Corynebacterium ulcerans
It is associated with diphtheria-like sore throats
Corynebacterium ulcerans
CTBA- Colonies have a surrounding brown halo
Corynebacterium ulcerans
BAP- Colonies have a narrow zone of Beta hemolysi
Corynebacterium ulcerans
Loeffler‘s serum agar- Colonies exhibit growth
Corynebacterium ulcerans
(+) Urease and gelatinases, (-) nitrate reduction
Corynebacterium ulcerans
It is an animal pathogen that humans can contract through direct contact with infected animals
Corynebacterium pseudotuberculosis
It produces a dermonecrotic toxin that causes death of various cell types
It can also produce diphtheria toxin
Corynebacterium pseudotuberculosis
CTBA- Colonies exhibit a black color and are surrounded with a brown halo
Corynebacterium pseudotuberculosis
BAP-Colonies are small and yellowish-white
Corynebacterium pseudotuberculosis
(+) Urease (-) gelatinase
Corynebacterium pseudotuberculosis
best specimens for isolation of C. diptheriae
Nasopharyngeal and throat swabs
Swab preferred for collection
calcium alginate swab
: Bacterial cells exhibit a beaded formation
Methylene blue statining
used for staining metachromatic granule
Neisser‘s and Albert‘s stains
Neisser‘s staining method is composed mainly of either
r methylene blue or crystal violet
the components of Albert‘s stain.
Malachite green and toluidine
CTBA and Tinsdale agar should be incubated for at least
48 hours at 35C
The multiplication of corynebacteria occurs within the range of
15C to 40C
It is the preferred medium for the isolation and identification of
corynebacteria
Cytine tellutite blood agar (CTBA)
It is a modification of Tinsdale agar
It is both a selective and differential medium
Cytine tellutite blood agar (CTBA)
It contains sheep blood, bovine serum, cysteine, and potassium tellurite
Cytine tellutite blood agar (CTBA)
Colonies of corynebacteria exhibit a black or brown color after
48 hrs of incubation
Cytine tellutite blood agar (CTBA)
(+) Black or brown colonies surrounded by a brown halo
CTBA: C. diphtheria, C.
ulcerans, and C. pseudotuberculosis
(+) Result: Colonies exhibit a black colorand are surrounded by abrown
halo
Tinsdale agar
It is useful for observing the microscopic morphology and metachromatic
granules of C. diphteriae
Loeffler‘s serum agar
(+) Result: C. diphteriae colonies exhibit a ―”poached-egg” appearance
Loeffler‘s serum agar
The metachromatic granules of C. diptheriae are called
―Babes-Ernst
bodies
This is used to observe the urease production of C. uralyticum
Christensen urea slant
it is a skin test used to determine the susceptibility of a person to diphtheria
. Schick test
The procedure involves the intradermal introduction of a small amount of diphtheria toxin
into the arm of the individual who is suspected to be harboring the disease
o (+) Result: Redness and Swelling around the site
Schick test
It produces a dermonecrotic toxin that causes death of various cell types
Corynebacterium pseudotuberculosis
