Microbiological profile and antibiotic susceptibility pattern of Gram-positive isolates at a tertiary care hospital

Gram-positive infections such as those by Staphylococcus aureus have contributed to the disease burden by increasing the morbidity and mortality rates in India. This study aims to determine the prevalence and the antibiotic susceptibility pattern of Gram-positive pathogens at a tertiary care hospital, Mumbai, Maharashtra, India.

This retrospective cross-sectional study was carried out from January, 2015 to December, 2017, at a tertiary care hospital in Mumbai, India. The clinical isolates were cultured, and identification was done using Vitek 2 culture system. The antibiotic susceptibility testing was done as per the Clinical Laboratory Standard Institute guidelines.

Out of 2132 (29%) Gram-positive isolates, S. aureus (49%) was the most common encountered pathogen, followed by Enterococcus spp. (24.5%) and coagulase-negative Staphylococcus (16%). Majority of the S. aureus were observed in patients with skin and soft-tissue infections (61.2%) followed by those suffering from respiratory (41%) and bloodstream infections (35%). Among the infections caused by S. aureus, the prevalence of methicillin resistance was 30%. While the MRSA isolates showed lower sensitivity toward co-trimoxazole (39%), clindamycin (30%), erythromycin (23%), and ciprofloxacin (10%), they showed higher susceptibility to linezolid (98%), vancomycin (98%), and teicoplanin (98%). All the isolates were found to be sensitive to daptomycin and tigecycline. While vancomycin-resistant enterococci (VRE) formed 7.5%, the linezolid-resistant enterococcus species was as high as 4.1%.

The study showed a high prevalence of MRSA and VRE, thereby emphasizing the increasing antimicrobial resistance pattern of the Gram-positive pathogens. Therefore, there is an urgent need for novel antimicrobial stewardship to restrict the ongoing resistance rate among the isolates.