Streptococcus gallolyticus Bacteremia: Experience from a Tertiary Center in South India

Introduction: Streptococcus gallolyticus is an important cause of bacteremia and infective endocarditis in adults. Studies from other parts of the world has shown a strong association between S. gallolyticus bacteremia and colonic neoplasia. The profile of S. gallolyticus bacteremia is understudied in Indian population. Materials and methods: We retrospectively analyzed the data of 16 patients with S. gallolyticus bacteremia obtained from microbiology registry. BacT/ALERT positive samples were inoculated into blood agar, chocolate agar, and MacConkey agar. Organisms were identified by the VITEK 2 microbial identification system, and susceptibility was done by the microbroth dilution method as per Clinical and Laboratory Standards Institute (CLSI) M100 guidelines. Clinical details were obtained from electronic medical records. Results: Majority of our isolates were S. gallolyticus subspecies pasteurianus. Total 16 patients had S. gallolyticus isolated from blood over a 1 year period. The median age was 58 years (IQR: 46.5-66). Eleven were males; type II diabetes mellitus and chronic liver disease were the common comorbidities observed in our patients. None of our patients had underlying infective endocarditis or colonic malignancy. Penicillin sensitivity was 81.2% while all the isolates were susceptible to ceftriaxone. Ampicillin resistance was seen in only one of the isolates. In-hospital mortality was 12.5%. Conclusion: Streptococcus gallolyticus subsp. pasteurianus is the commonest subspecies of S. gallolyticus isolated in our population. Unlike previous studies, colonic neoplasia and infective endocarditis were rare in our patients. Type II diabetes mellitus and chronic liver disease were the commonest risk factors identified in patients with S. gallolyticus bacteremia.