Prevalence of methicillin resistant staphylococcus aureus and its SCCmec type among students at a private dental college hospital in Chennai

Background: Since asymptomatic nasal carriage of Methicillin-resistant S. aureus (MRSA) is on the rise among healthcare professionals (HCPs), their prompt detection and decolonization would substantially decrease disease transmission. The study's primary goal was to identify MRSA nasal carriers among dental students/CRIs and determine their SCCmec type and their susceptibility to mupirocin. Methods: Anterior nasal swabs from 102 healthy dental students/ CRIs were collected aseptically and subjected to standard microbiological testing. The antibiotic susceptibility pattern of the S. aureus isolates was determined by Kirby Bauer disc diffusion method and mecA-mediated oxacillin (methicillin) resistance was determined using the cefoxitin disc method. PCR analysis of MRSA isolates determined the presence of mecA and their SCCmec types. D test deduced inducible clindamycin resistance. Results: Of the 102 participants screened, only 8(7.8%) carried S. aureus. Antibiotic susceptibility testing revealed that 5/8(62.5%) were MRSA isolates. Of which, only 2 MRSA isolates harbored mecA, and both belonged to the SCCmec type V. All S. aureus isolates were sensitive to Vancomycin, teicoplanin, and tigecycline when tested using agar screening method while 2/8 (25%) of the S. aureus isolates were D test positive and belonged to iMLSB phenotype. Conclusion: MRSA nasal carriers amongst HCWs/dental students are a cause of concern as they are a significant reservoir for transmission of MRSA among their co-workers as well as the community. Our results signify the need for screening for MRSA carriage and decolonization with mupirocin to substantially decrease the transmission of MRSA among dental students/patients

Antibiotic resistance and Staphylococcal super antigenic determinants in methicillin resistant Staphylococcus aureus isolated from anterior nares of dental students

Background: Staphylococcus aureus primarily inhabits the human anterior nares. Asymptomatic Methicillin-resistant Staphylococcus aureus (MRSA) nasal carriage in healthcare professionals makes them potential MRSA reservoirs. Since identification and decolonization would promote cross-contamination reduction and curb communal transmission, this study was designed to identify MRSA nasal carriers among dental students and detect staphylococcal super antigenic determinants among them. Methods: Staphylococci isolates (n=52) from dental students(n=42) were investigated in the study. Following initial microbial speciation and antimicrobial susceptibility determination using standard identification methods, the MRSA strains were identified phenotypically using cefoxitin disc (30 µg). Genes encoding the virulence determinants, namely, TSST (test), enterotoxins (sea and seb), and cytotoxin (pvl), were looked for by PCR. Results: Only 15.09% of isolates were identified as Staphylococcus aureus, and all of them (n=8) were scored as MRSA using the cefoxitin disc diffusion method. None of the tested isolates showed the presence of virulence determinants in standard molecular techniques. Conclusion: Lower prevalence of S. aureus, MRSA, coupled with the absence of virulence determinants in the strains, suggests strategies for better surveillance. Tracking virulence-causing genes in nasal carrier S. aureus strains could enhance efforts to prevent infection outbreaks