universe84a

Diphtheroids in Gram Stain

Diphtheroids in Gram stain showing Gram-positive bacilli short and thick evenly stained as shown above picture. They are defined as aerobic, pleomorphic, non-sporulating Gram-positive bacilli which are more uniformly stained, lack the metachromatic granules, and are arranged in a palisade arrangement. Even though they are usually commensals of the skin and mucous membranes they are frequently reported in association with nosocomial infections and a vast majority of them are exhibiting antibiotic resistance too.

The list of Diphtheroids are-

1. Corynebacterium pseudotuberculosis,
2. Coryne- bacterium ulcerans,
3. Corynebacterium renale,
4. Corynebacterium bovis,
5. Corynebacterium striatum,
6. Corynebacterium minutissimum,
7. Corynebacterium pseudodiphtheriticum
8. Corynebacterium haemolyticum, etc.

Medical Importance of Diphtheroids

1. Studies have reported multidrug-resistant Corynebacterium striatum, which was otherwise considered as a saprophyte of skin and mucous membrane to be a cause of long-standing open wound infections and more recently as a cause of septic arthritis of a native knee joint and shoulder joint.
2. Corynebacterium pseudotuberculosis has been shown to cause lymphadenitis in humans and because of the potential to cause zoonotic infections, milk and meat consumers are exposed to greater risk.
3. C. pseudodiphtheriticum has been mostly found to cause respiratory tract infections, nosocomial pneumonia, tracheitis, bronchitis, and a number of other infections
4. Corynebacterium minutissimun has been isolated from superficial skin infections and very rarely from invasive infections
5. Corynebacterium ulcerans toxigenic strains have been isolated from nasopharyngeal infections.
6. Corynebacterium xerosis species have been found in the conjunctival sac and on the skin and mucous membranes.
7. A study conducted on the topic ‘Diphtheroids-Important Nosocomial Pathogens’ by Rashmi Chandran and et.al. shown various species of diphtheroids isolated as pure growth from clinical specimens whose Gram’s smear revealed numerous inflammatory cells with Gram-positive bacilli and had clinical evidence.
8. From the same study, diphtheroids isolated from bloodstream infections were considered clinically significant if clinical condition favored infection and if there was pure growth of diphtheroids within 48 hours.
9. From the same study, nosocomial strains of diphtheroids survive in the form of biofilms and cause multidrug-resistant infections.

Further  Readings

1. Bernard K. The genus Corynebacterium and other medically relevant coryneform-like bacteria. J Clin Microbiol. 2012;50:3152–58. [PMC free article] [PubMed] [Google Scholar]
2. Funke G, Bernard KA. Manual of Clinical Microbiology. Ninth Edition. Washington DC: ASM Press; 2007. Coryneform Gram-positive rods. In: Murray PR, Baron EJ, Jorgensen JH, Landry ML, Pfaller MA, Eds; pp. 485–514. [Google Scholar]
3. Funke G. Topley and Wilson’s Microbiology and Microbial Infections, Bacteriology. Tenth Edition. Volume 2. ASM Press; 2010. Corynebacteria and rare coryneform. In: Borriello SP, Murray PR, Kunke G, Eds; pp. 977–97. [Google Scholar]
4. Purbasha G, Khushboo Kama M, Yugal Kishor S, Rabindra Nath M, Kedar Nath D. Co-infection of Herpes genitalis with Corynebacterium amycolatum: A rare case report from the district of Western Maharashtra, India. JCDR. 2012;6(7):1298–300. [Google Scholar]
5. Biswal I, Dawar R, Deb M, Gaind R, Mohapatra S. Corynebacterium striatum: An emerging nosocomial pathogen in a case of laryngeal carcinoma. Indian J Med Microbiol. 2014;32(3):323–24. [PubMed] [Google Scholar]
6. Westblade LF, Shams F, Duong S, Tariq O, Bulbin A, Klirsfeld D, et al. Septic arthritis of a native knee joint due to Corynebacterium striatum. J Clin Microbiol. 2014;52:1786–88. [PMC free article] [PubMed] [Google Scholar]
7.  Feced Olmos CM, Alegre Sancho JJ, Ivorra Cortés J, Román Ivorra JA. Septic arthritis of the shoulder due to Corynebacterium striatum. Rheumatol. Clin. 2013;9:383. [PubMed] [Google Scholar]
8. Bastos BL, Portela RW Dias, Dorella FA, Ribeiro D, Seyffert N, Castro T L de Paula, et al. Corynebacterium pseudotuberculosis: Immunological Responses in Animal Models and Zoonotic Potential. J Clin Cell Immunol. 2012; S4:005. [Google Scholar]
9.  Camello TCF, Souza MC, Martins CAS, Damasco PV, Marques EA, Pimenta FP, et al. Corynebacterium pseudodiphtheriticum isolated from relevant clinical sites of infection: a human pathogen overlooked in emerging countries. Lett Appl Microbiol. 2009;48(4):458–64. [PubMed] [Google Scholar]
10. Shin JY, Lee WK, Seo Y-H, Park YS. Postoperative abdominal infection caused by Corynebacterium minutissimum. Infect Chemother. 2014;46(4):261–63. [PMC free article] [PubMed] [Google Scholar]
11. Nagassar RP, Nicholson AM, Williams W, Bridgelal-Nagassar RJ. Diphtheroids as a cause of endocarditis in a haemodialysis patient. BMJ Case Reports. 2012 doi:10.1136/bcr.10.2011.4894. [PMC free article] [PubMed] [Google Scholar]
12. Dalal A, Likhi R. Corynebacterium minutissimum bacteremia and meningitis: a case report and review of literature. J Infect. 2008;56(1):77–79. [PubMed] [Google Scholar]