Biofilm colonization of Mycobacterium abscessus: New threat in hospital-acquired surgical site infection.

INTRODUCTION: Rapidly growing non-tuberculous mycobacteria (NTM) are hazardous cause of post-operative soft tissue infection leading to nosocomial outbreaks following various surgical procedures, especially laparoscopic surgeries using heat sensitive, non-autoclavable surgical instruments.

METHODOLOGY: Surgery department of our hospital noticed increase in rate of post-laparoscopic abdominal port site infection (PSI) and informed the Microbiology Department. A prospective investigational study of defined cases with the aim of source tracing and formulation of infection control measures was initiated. Pus or wound scrapings were collected and processed for aerobic, anaerobic bacteria and Mycobacterium, both by staining and culture. Environmental samples were collected from laparoscopic instruments, and different parts of operation theatre (OT). Mycobacterial isolates were speciated by line probe assay. All the cases were treated with clarithromycin and ofloxacin±amikacin.

RESULTS: Among 15 cases of PSI, 11 patients had undergone laparoscopic cholecystectomy, 3 had laparoscopic mesh hernioplasty and one had laparoscopic orchidopexy. Of the 13 pus/discharge specimens examined, 11 revealed growth of NTM. All the isolates were identified as Mycobacterium abscessus by line probe assay. Scraping of biofilm from the disinfectant tray also produced growth of the same organism. Plastic trays used for disinfectants were replaced with metal trays and instructed to do mechanical scrubbing before autoclaving at regular interval. No similar PSI cases were notified after those measures were taken, till date.

CONCLUSIONS: This study has shown the need of culture and identification of pathogens causing persistent post surgical wound infections and illuminated importance of rapid source tracing in resource constraint situation which could control outbreak.