CORYNEBACTERIUM Flashcards
- Catalase positive, gram-positive rods
- Non–acid-fast, non–spore-forming, and mostly
non-branching rods
CORYNEBACTERIUM
C. jeikeiumand C. urealyticum
Lipophilic Corynebacteria
o C. diphtheriae, C. pseudotuberculosis,
C. pseudodiphtheriticum, C. striatum, C.
ulceransand C. xerosis
Non-Lipophilic Corynebacteria
a can be divided into non lipophilic
and lipophilic species
* Majority of the species are found as indigenous
microbiota of the skin and mucous membrane of
humans and animals. Species are pathogenic to
animals, plants, and humans.
found in fresh water.
Corynebacterium are also found in salt water,
soil, and air
Species are non-motile, non-encapsulated, nonspore forming and highly theomorphic rod
Specie are glucose and maltose fermenters
except
C. pseudodiphthericum and C. urealyticum.
slightly curved, grampositive rods
“club shape” or coryneform
Cells are arranged singly, in “palisades” of
parallel cells or in pairs of cells connected after
cell division to form V or L shapes: “Chinese
letters” appearance
“diphtheria-like
Specie causing human infections in Corynebacterium
C.
diphtheriae, C. jeikeium, C. pseudotuberculosis,
C. pseudodiphthericum, C. ulcerans, and C.
urealyticum
Majority of the species are found as indigenous microbiota of the skin and mucous membrane of humans and animals. Species are pathogenic to animals, plants, and humans.
CORYNEBACTERIUM
AKA: diphtheria bacillus or Kleb-Loffler bacillus
CORYNEBACTERIUM DIPHTHERIAE
Facultative anaerobe, Inhabits the human nasopharynx in carrier
CORYNEBACTERIUM DIPHTHERIAE
inhalation of contaminated respiratory droplets or direct contact with infected cutaneous lesions.
MOA for Corynebacterium diphtheriae
Readily killed by heat and by most of the usual disinfectants.
• Glucose and maltose fermenter
CORYNEBACTERIUM DIPHTHERIAE
VF OF CORYNEBACTERIUM DIPHTHERIAE
Diphtheria toxin
Preferred medium for Preferred medium
Enriched medium with
serum, cysteine and potassium tellurite
o Rounded ends and “club-shaped swelling”
o highly pleomorphic cells are arranged in pairs and create X, V, Y and L formation that closely resembles Chinese letters.
Microscopy of CORYNEBACTERIUM DIPHTHERIAE
(-) Urease; (+) Nitrate reduction.
Biochemical Test for CORYNEBACTERIUM DIPHTHERIAE
Nasopharyngeal and throat swabs
Best specimen for CORYNEBACTERIUM DIPHTHERIAE
THREE BIOTYPES OF CORYNEBACTERIUM DIPHTHERIAE
• Intermedius
• Mitis
• Gravis
Very small, flat, dry, and grayish-black
colonies; non-haemolytic
Intermedius
Small, black and convex that have
“fried-egg appearance
Mitis
Large, flat and dark gray colonies
“daisy-head appearance”
Gravis
used for the visualization of metachromatic granules which is also known as Much granules.
Albert stain
• Heat-labile
• Produced by strains with a lysogenic b-phage
that carries the TOX gene.
DIPHTHERIA TOXIN
• Tissue necrosis and exudates formation
(psedomembrane lining) over the tonsils, larynx
and pharynx
• Alkaline pH (7.8 to 8.0), aerobic environment
and sufficient amount of iron in the medium.
DIPHTHERIA TOXIN
Acute, infectious disease characterized by production of systemic toxin and false membrane lining (Pseudomembranous formation) of the throat mucous membrane → respiratory obstruction.
RESPIRATORY DIPHTHERIA
(+): 4 mm to 5 mm fine precipitin lines at 45 angle to the streaks.
Immunodiffusion Test - Elek’s Test
AKA: diphtheria antitoxin test (in
vivo test)
Guinea pig lethal Test
detection of diphtheria antitoxin
(in vitro)
Tissue Culture Test
used for detection of toxin
genes
Polymerase Chain Reaction
Preferred medium
for isolation and identification of
crynebacterium
Cystine Tellurite Blood Agar
o Modification of
the Tinsdale agar o Selective and
Differential
o Contains sheep blood, bovine serum,
cysteine
Cystine Tellurite Blood Agar
Positive reaction for Cystine Tellirite Blood Agar
Colonies of corynebacterial exhibit a
black or brown color after 48 hours
C. diphtheriae, C. ulcerans and C.
pseudotuberculosis.
Positive organism for CTBA
Sheep blood,
cystine, potassium tellurite and sodium thiosulfate
Tinsdale Agar
o (+) Black color surrounded by halo
o (+) all bio types of C. diphtheriae
Tinsdale Agar
Urea production: C. urealyticum
Christensen Urea Slant
Microscopic and metachromatic
granules of C.
diphtheriae.
Pai’s Slant or Loeffler’s Serum Agar
(+): C. diphtheriae
exhibit “poached- egg” appearance
Pai’s Slant or Loeffler’s Serum Agar
Metachromatic diphtheriaeare called
Babes ernst bodies
o Used to determine the susceptibility of a
person to diphtheria.
o Involves the intradermal introduction of
a small amount of the diphtheria toxin
into the arm of the suspected individual.
Schick Test
(+): Redness and Swelling around the
site.
Schick Test
Most frequently isolated and most clinically significant.
• Urinary pathogen, strict aerobe and lipophilic
• Do not ferment glucose and maltose
• Microscopy: V shaped and palisades
• Culture: BAP –pinpoint, white smooth, non-
haemolytic
• Urease producer
• Most frequent isolated and most clinically
significant among them all.
C. UREALYTICUM
• Normal flora of nasopharynx
• Respiratory infection, UTI, cutaneous wound
infection in immunocompromised.
• Microscopy: arranged in parallel rows or
palisades and do not exhibit any other characteristics “pleomorphism” that is similar to other.
• Urease and nitrate positive
C. PSEUDODIPHTHERITICUM
• Skin normal flora in inguinal, axillary and rectal sites.
• Obligate aerobe and antibiotic resistant
• Immunocompromised, Common cause of diphtheroid prosthetic valve endocarditis in
adults.
• Microscopy: Pleomorphic, club-shaped and
arranged in V-shaped
• Urease and Nitrate negative
C. JEIKEIUM
• Animal contact and unpasteurized dairy products.
• Skin ulcers and exudative pharyngitis
• Associated with diphtheria-like sore throats.
• Culture: BAP-narrow zone of b-hemolysis
• CTBA - brown halo
• Loeffler’s serum agar: Exhibit growth
• (+): Urease and gelatinase; (-) nitrate reduction.
C. ULCERANS
• Animal pathogens that human can contract thru direct contact with infected animals.
• Dermonecrotic toxin causes death of various cell types
• Diphtheria toxin (causative agent)
• Culture: CTBA –black color and surrounded by
brown halo
• BAP: small and yellowish-white
• (+) urease; (-) gelatinase
C. PSEUDOTUBERCULOSIS
Preferred for collection.
Calcium alginate swa
