Bacteriology & Applied Microbiology

A total of 375 Staphylococci were isolated from clinical samples received in a tertiary care hospital of Nepal during 2015-2017 were included to study antibiotic susceptibility pattern, biofilm formation and persister cells development. Standard microbiological procedure was used to identify staphylococcal species and CLSI guideline was followed to determine antibiotic susceptibility pattern. Biofilm production was detected using both phenotypic and genotypic methods.Among 375 Staphylococcal isolates, 161 isolates were identified as S. aureus comprising 81% methicillin resistant and 19% methicillin sensitive S. aureus and remaining coagulase negative Staphylococcus spp. While most of the isolates were resistant to Penicillin, these were sensitive towards Chloramphenicol, Tetracycline and Clindamycin. Among different

phenotypic assays used for detection of biofilm formation, tissue culture method detected biofilm production in 22.1% isolates followed by tube method and Congo red agar method which detected only 16.8% and 5.3%, respectively. On further verification, PCR detected ica genes in 23% of staphylococcal isolates thus revealing the biofilm formation in these samples. In-vitro persister assay is undergoing to study the causal link between persister cells and treatment failures in these isolates.