Emergence of coryneform bacteria as pathogens in nosocomial surgical site infections in a tertiary care hospital of North India

Purpose: A prospective study was conducted to assess the role of coryneform bacteria in surgical site infections among obstetric and gynecological patients undergoing surgery. Materials and methods: The surgery was graded according to the degree of contamination, and surgical site infections (SSIs) were classified as superficial or deep. Pus samples were collected from SSIs according to rigorous aseptic precautions, and the quality of specimens was assessed by Q-score. A detailed clinical and treatment history was elicited from all patients. The samples were processed using standard protocols. Coryneform bacteria were considered significant pathogens only if they fulfilled rigorous clinical and microbiological criteria. Antibiotic susceptibility testing was performed using the Kirby-Bauer method according to the CLSI guidelines. Results: In total, 127 patients developed SSIs among 882 postoperative patients. Of these, 89 (70.1%) were culture positive: 40 (44.9%) were Gram-positive cocci, 27 (30.3%) were coryneform, and 22 (24.7%) were Gram-negative bacilli. All coryneform-infected patients had fever and post-operative wound dehiscence leading to a prolonged hospital stay. The most commonly isolated organism was Staphylococcus aureus (33.7%), followed by Corynebacterium amycolatum (11.2%), Escherichia coli (8.9%), Citrobacter spp. (7.8%) and coagulase-negative Staphylococci (6.7%). In our study, 45.5% were ESBL producers, 18.2% were Amp C producers, and 40% were MRSA. All the coryneform bacteria were multidrug resistant, and 51.8% of isolates were sensitive to only gatifloxacin and vancomycin. Symptomatic improvement was observed in all coryneform-infected patients after the administration of appropriate therapy. Conclusion: Coryneform bacteria appear to be emerging as significant nosocomial surgical site pathogens. The high level of multidrug resistance observed in coryneform bacteria in our study is cause for alarm.