Corynebacterium species


  • As a term, "coryneform ("club-shaped") bacteria" is sometimes used to denote a wide range of Gram-positive rods based on staining characteristics and DNA content (specific G/C ratios).
    • Corynebacterium spp. included, but also others (Arcanobacterium, Rothia mucilaginosa).
  • A genus with two major human species:
    • Corynebacterium diphtheriae (see separate module)
    • Non-diphtherial species are also referred to as "diphtheroids." This group is now classified based on RNA homology rather than within the previous coryneform group.
      • Many are part of normal human skin flora.
    • Below is a partial listing of the most commonly encountered pathogens and a more complete listing (53 pathogens) in Bernard[10].
      • Organisms remain uncommon causes of human infection.
    • Zoonoses (usually), rare human pathogen:
      • C. pseudotuberculosis: cause of caseous lymphadenitis in goats and sheep; human infection typically derived from contact with infected animals. Occasional agent of human lymphadenitis or respiratory diphtheria.
      • C. ulcerans: infection from handling infected animals or contact with contaminated milk.
        • An occasional cause of human respiratory diphtherial infection.
        • See the diphtheria module for public health and treatment recommendations.
    • Other occasional human pathogens: often afflicting hospitalized/immunocompromised patients; organisms typically with significant antibiotic-resistance profiles.
      • C. amycolatum: may be under-recognized as frequently misidentified as C. jeikeium or C. urealyticum.
      • C. bovis: bacteremia (rare)
      • C. hemolyticum: now Arcanobacterium hemolyticum.
      • C. jeikeium: originally termed group JK, may cause bacteremia, endocarditis, device/prosthesis infections, and wound infections, especially in immunocompromised patients with hematological disorders or vascular catheters.
      • C. kroppenstedtii: implicated as a cause of granulomatous mastitis.
      • C. striatum: described as an emerging nosocomial pathogen; endocarditis, lung or bone infections, device infections, septic arthritis
        • Often resistant to fluoroquinolones, aminoglycosides, TMP/SMX, aminoglycosides and many beta-lactams.
        • One comprehensive review described that 100% of isolates were susceptible to vancomycin, linezolid, teicoplanin, piperacillin-tazobactam, amoxicillin-clavulanate and cefuroxime.[3]
      • C.tuberculostearicum:may be misidentified by lab; often multidrug-resistant.
      • C. urealyticum: capable of hydrolyzing urea. Genitourinary infections (encrusted cystitis) >> bacteremia, endocarditis, wound infections.
      • C. xerosis: rare and usually afflicting immunocompromised or cardiac valve patients.
  • Species identification is recommended for any isolate thought to be causing human infection.
  • Non-diphtheriae Corynebacterium spp. that may carry the tox-gene that could produce diphtheria toxin:
    • Corynebacterium belfantii, Corynebacterium rouxii, Corynebacterium ulcerans, Corynebacterium pseudotuberculosis and Corynebacterium silvaticum.
  • Gram-positive rods [Fig 1], catalase-positive and non-motile.
    • It may be aerobic or facultatively anaerobic.
    • Not acid-fast.
    • Most grow on conventional media, though some require the addition of lipids for growth.

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Last updated: June 8, 2024