P.O. Box 131375, Bryanston, 2074
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Bryanston Gate, 170 Curzon Road
Bryanston, Johannesburg, South Africa
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MICROBIOLOGY LEGEND
CYCLE 36 ORGANISM 5
Corynebacterium
Corynebacteria (from the Greek words koryne, meaning club, and bacterion, meaning little rod) are
gram-positive, catalase-positive, aerobic or facultatively anaerobic, generally nonmotile rods. The
genus contains the species Corynebacterium diphtheriae and the nondiphtherial Corynebacteria,
collectively referred to as diphtheroids.
Nondiphtherial Corynebacteria, originally thought to be mainly contaminants, have increasingly
over the past 2 decades been recognized as pathogenic, especially in the elderly and
immunocompromised hosts. They are ubiquitous in nature and commonly colonize human skin and
mucous membranes. Some of these species are also pathogenic in animals, especially in livestock;
others appear specific to humans.
Specific pathogenic groups or species include the following:
 Corynebacterium ulcerans
 C. pseudotuberculosis (also known as Corynebacterium ovis)
 Corynebacterium pyogenes
 A. haemolyticum (formerly known as Corynebacterium haemolyticum)
 Corynebacterium aquaticum
 C. pseudodiphtheriticum (also known as Corynebacterium hofmannii)
 Group D2 (also known as Corynebacterium urealyticum)
 Group E
 C. jeikeium (i.e., group JK)
Laboratory Identification
 Small, nonmotile, irregularly staining pleomorphic Gram-positive rods with club-shaped
swelled ends but no spores; may be straight or slightly curved
 Palisade arrangement of cells in short chains ("V" or "Y" configurations) or in clumps
resembling "Chinese letters"
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Page 1 of 3
P.O. Box 131375, Bryanston, 2074
Ground Floor, Block 5
Bryanston Gate, 170 Curzon Road
Bryanston, Johannesburg, South Africa
804 Flatrock, Buiten Street, Cape Town, 8001
www.thistle.co.za
Tel: +27 (011) 463 3260
Fax: +27 (011) 463 3036
Fax to Email: + 27 (0) 86-557-2232
e-mail : service@thistle.co.za
 Cells tend to lie parallel to one another (palisades) or at acute angles (coryneforms), due to
their snapping type of division
 Vary greatly in dimension, from 0.3 to 1 um in diameter and 1.0 to 8.0 um in length
 May also contain inclusion bodies, known as metachromatic granules, which are composed of
inorganic polyphosphates (volutin) that serve as energy reserves and are not membrane
bound
 Internal metachromatic granules densely stain ruby red while the rest of the bacillus stains
blue, when stained with an aniline dye such as toluidine blue O or methylene blue
 Cells appear to be banded or beaded with irregularly staining granules; may show alternate
bands of stained and unstained material (giving the appearance of septa)
 Aerobic or facultatively anaerobic
 Fermentative metabolism (carbohydrates to lactic acid); form acid but not gas from certain
carbohydrates
 Fastidious; Slow growth on enriched medium
 Catalase positive
 Cell wall containing unusual lipids: meso-diaminopimelic acids; arabino-galactan polymers;
short-chain mycolic acids (member of CMN (Corynebacterium, Mycobacterium, Nocardia)
group)
 Corynebacterium urealyticum strongly urease positive
Blood agar plate culture of Corynebacterium
pseudodiphtheriticum
Gram stain of Corynebacterium spp. demonstrating
"Chinese letters" formations
Distinguishing Characteristics of Corynebacterium spp.
CELLULAR
MORPHOLOGY
ORGANISM
HEMOLYSIS
SUGAR
FERMENTATION
GLUCOSE
SUCROSE
TOXIN
C. diphtheriae
Slender pleomorphic rods; often
club-shaped; often banded or
beaded with irregularly staining
granules
+
+
-
+
C. pseudodiphtheriticum
Short rods; no granules; clubs rare
-
-
-
-
C. xerosis
Polar staining rods; few club forms
-
+
+
-
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Accredited to ISO 17043
Certificate available on request or at www.sanas.co.za
Page 2 of 3
P.O. Box 131375, Bryanston, 2074
Ground Floor, Block 5
Bryanston Gate, 170 Curzon Road
Bryanston, Johannesburg, South Africa
804 Flatrock, Buiten Street, Cape Town, 8001
www.thistle.co.za
Tel: +27 (011) 463 3260
Fax: +27 (011) 463 3036
Fax to Email: + 27 (0) 86-557-2232
e-mail : service@thistle.co.za
Clinical Syndromes
Determined by site of infection, host immunity, and virulence of the organism
 Corynebacterium diphtheriae: toxigenic strains cause diphtheria in humans
 Corynebacterium jeikeium: opportunistic infections (especially in immunocompromised
patients)
 Corynebacterium urealyticum: urinary tract infections (UTI’s); rare but important
 Corynebacterium pseudotuberculosis: subacute relapsing lymphadenitis
 Corynebacterium ulcerans: pharnygitis
 Corynebacterium xerosis: bacteraemia, skin infections, pneumonia in immunocompromised
hosts (e.g., patients with blood disorders, bone marrow transplants, intravenous catheters)
and pharyngitis
 Corynebacterium pseudodiphtheriticum: endocarditis and lower-respiratory tract infections
Treatment, Prevention & Control
 C. diphtheriae
 Diphtheria antitoxin (DAT), has been the mainstay of therapy - used for neutralizing
exotoxin, effective in conjunction with antibiotic therapy
 Toxoid - toxoid preparations are used for vaccines as active immunization for
diphtheria. Usually given in conjunction with pertussis and tetanus vaccines (DPT vaccine)
or as a booster with tetanus (TD)
 Supportive care is also important, including rest, airway management, observation for
development of secondary lung infections and management of cardiac and neurologic disease
complications.
 Diphtheroids
 Antibiotics are the treatment of choice for nondiphtherial Corynebacteria infections. Many
species and groups are sensitive to various antibiotics, including penicillins, macrolide
antibiotics, rifampin, and fluoroquinolones. However, antibiotic susceptibility can vary, and
susceptibility testing is recommended.
References
1. http://en.wikipedia.org/wiki/Corynebacterium
2. http://emedicine.medscape.com/article/215100-overview#a0199
3. http://www.life.umd.edu/classroom/bsci424/pathogendescriptions/Corynebacterium.htm
Questions
1. Discuss the morphological characteristics of Corynebacterium spp.
2. How would you distinguish between the different species in your laboratory?
3. Discuss the role of Corynebacterium in disease.
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Certificate available on request or at www.sanas.co.za
Page 3 of 3