Emergence of coryneforms in osteomyelitis and orthopaedic surgical site infections

Background Coryneform species other than Corynebacterium diphtheriae are coming up as important pathogens with the potential to cause serious and life-threatening infections not only in immunocompromised but in immunocompetent individuals as well. The exact infectious potential of these bacteria and their rational antimicrobial treatment is a challenging but essential task. Method The study was conducted in the Department of Microbiology and the Department of Orthopaedics, JNMCH, AMU, Aligarh between August 2007 and May 2009. Pus samples were collected from patients of osteomyelitis and other bone infections including orthopaedic surgical site infections. The Corynebacterium species isolated in the study was identified using standard microbiological techniques and antimicrobial sensitivity testing was done by Kirby bauer disc diffusion method. Results A total of 312 Corynebacterium species were isolated. The majority of the coryneforms were isolated from the immunocompetent patients 270 (86.54%). C.jeikium was the most common coryneform isolated. Nearly half of the patients 153 (49.04%) had acute infection caused by Corynebacterium species after orthopaedic surgery, a quarter 66 (21.15%) had chronic infection and 72 (23.08%) patients had device-related infection. Coryneforms exhibited maximum resistance to aminoglycosides (58.65%) and ß-lactams (penicillin group-57.55%. C.jeikium was found to be the most resistant amongst all the Corynebacterium species. Conclusion The study highlights the fact that the coryneforms are no longer just opportunistic pathogens but they are also becoming important pathogens among immunocompetent individuals as well. The emergence of drug resistance amongst these isolates is of most concern. More studies should be done on identification and on antimicrobial susceptibility of these organisms for the proper treatment of patients with such infections.