Cardiobacterium hominis

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Cardiobacterium hominis
Cardiobacterium hominis on blood agar plate
Scientific classification
C. hominis

Cardiobacterium hominis is a Gram-negative bacillus (rod-shaped) bacterium commonly grouped with other bacteria into the HACEK group. It is one of several bacteria that is normally present in the mouth and upper part of the respiratory tract such as nose and throat. However, it may also rarely cause endocarditis, an infection of the heart valves.[1]


C. hominis is a catalase-negative, oxidase-positive, indole-producing, Gram-negative rod.[2] Its morphology has classically been described as highly pleomorphic and irregularly staining, although homogeneous bacilli with uniform shapes may be seen with the addition of yeast extract.[2]


Cardiobacterium hominis-induced lacrimal abscess of the right eye with surrounding acute inflammation

Historically, C. hominis has been sensitive to penicillin and penicillin derivatives such as ampicillin.[3] However, penicillin-resistant strains, including those that produce beta-lactamases, have been described with increasing frequency.[4] Clinical guidelines thus recommend that C. hominis and other HACEK organisms be presumed to harbor ampicillin resistance and therefore be treated with a third-generation cephalosporin.[3] C. hominis and other HACEK organisms also exhibit in vitro susceptibility to trimethoprim-sulfamethoxazole, fluoroquinolones, and aztreonam.[3] C. hominis is often resistant to erythromycin.[5] Since cefotaxime use may be not appropriate for C. hominis endocarditis, an alternative regimen might include association of co-amoxiclav and gentamicin.[6]


  1. Malani, AN; Aronoff, DM; Bradley, SF; Kauffman, CA (September 2006). "Cardiobacterium hominis endocarditis: Two cases and a review of the literature". European Journal of Clinical Microbiology & Infectious Diseases. 25 (9): 587–95. doi:10.1007/s10096-006-0189-9. PMC 2276845. PMID 16955250.
  2. 2.0 2.1 Savage, DD; Kagan, RL; Young, NA; Horvath, AE (January 1977). "Cardiobacterium hominis endocarditis: Description of two patients and characterization of the organism". Journal of Clinical Microbiology. 5 (1): 75–80. PMC 274535. PMID 833269.
  3. 3.0 3.1 3.2 Wilson, WR; Karchmer, AW; Dajani, AS; Taubert, KA; et al. (December 1995). "Antibiotic treatment of adults with infective endocarditis due to streptococci, enterococci, staphylococci, and HACEK microorganisms. American Heart Association". JAMA. 274 (21): 1706–13. doi:10.1001/jama.274.21.1706. PMID 7474277.
  4. Lu, PL; Hsueh, PR; Hung, CC; Teng, LJ; et al. (May 2000). "Infective endocarditis complicated with progressive heart failure due to beta-lactamase-producing Cardiobacterium hominis". Journal of Clinical Microbiology. 38 (5): 2015–7. PMC 86656. PMID 10790145.
  5. Pfaller, Michael A.; Murray, Patrick R.; Rosenthal, Ken S. (2009). Medical Microbiology. Philadelphia: Mosby / Elsevier. p. 374. ISBN 0-323-05470-6.
  6. Torok, Estee; Moran, Ed; Cooke, Fiona (2009). Oxford Handbook of Infectious Diseases and Microbiology. Oxford University Press. ISBN 9780198569251.[full citation needed]

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