Understanding the Local Epidemiology of Methicillin-Resistant Staphylococcus aureus by Pulsed-Field Gel Electrophoresis in an Indian Tertiary Care Centre

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of community and hospital-acquired infections (HAIs). In the year preceding this study, our laboratory reported an MRSA isolation rate of 2% from 50,549 specimens. Molecular typing of MRSA identifies sources of infection, transmission chains and informs infection control practices, and pulsed-field gel electrophoresis (PFGE) is the gold standard. This study was conducted to gain an understanding of the local molecular epidemiology of MRSA in our hospital using PFGE, to inform hospital infection control practices.Methods: This prospective longitudinal study was conducted in the microbiology laboratory of our 2,200-bed tertiary care teaching hospital in Mumbai, India.The antibiotic susceptibility profiles and pulsed-field profiles (PFPs) of 100 consecutive non-duplicate clinical isolates of MRSA were obtained. The PFPs were compared to check for relatedness of isolates. The distribution of various pulsotypes across disciplines and hospital locations was examined.Results: Clinical specimens accounted for 86 (86%) of the MRSA isolates, whilst 14 (14%) were from screening of healthcare workers. Maximum isolates, 68 (68%), were from surgical disciplines. Confirmed HAIs accounted for 25 (25%) MRSA isolates. Seventeen antibiotypes were obtained and there was no correlation between antibiotype and pulsotype. Totally 43 pulsotypes were identified, with most isolates, 40 (40%), belonging to pulsotype 1. Seven clusters were identified. Cluster I had maximum pulsotypes, 14, and 58 (58%) isolates. Isolates belonging to clusters I and II were found in all hospital locations. Relatedness was observed between isolates from HAIs and screening specimens, and between community and HAI isolates.Conclusions: PFGE typing revealed the disciplines at greatest risk from MRSA in our hospital. The commonality between MRSA isolated from HAIs and screening of healthcare workers, and between MRSA isolated from HAIs and from community-acquired infections highlighted the horizontal transmission of MRSA and the need to reinforce infection control measures to limit this.

Cluster Analysis of Clinical, Food, and Handler Methicillin-Resistant Staphylococcus Aureus Isolates Characterized by Pulse Field Gel Electrophoresis

“…The S. aureus forms no spores, however, may result in contaminating the food products throughout the processing and preparation of the food (6) . It is capable of https://www.indjst.org/ growing in many different temperature values (7 -48.5 o C; optimal 30-37 o C), pH (4.2 -9.3; optimal 7-7.5), and concentration of the NaCl up to 15%.…”

“…The contamination of the S. aureus in the food products may take place from environment throughout the processing and handling (13) . Incorrect practices of the food handling in retail food industries have been considered to be contributing to high numbers of the outbreaks of the (1,6) . The researchers showed that most outbreaks of the FBD are a result of those practices (4) .…”

“…Pulse Field Gel Electrophoresis (PFGE) is viewed as gold standard for the S. aureus of the genotyping due to its efficiency (its reproducibility and discriminatory powers) and practice (3,4) . For the purpose of identifying epidemiologic properties of the isolates of the MRSA and more significantly, for studying the progression and the spreading of the epidemic clones, the CDC established a molecular network of the sub typing (Pulse Net) for the surveillance of the foodborne diseases and have created a national database of the S. aureus profiles to investigate the outbreaks of the MRSA and the global tracking of its strain type (6) . This study aimed at applying the PFGE-based method as a valuable tool used by epidemiological and source tracking study of MRSA isolates from various environments in Iraq, particularly those causing food poisoning.…”