Detection of Methicillin-resistant Staphylococcus aureus (MRSA) and biofilm formation among dental patients and dental health care workers: cross sectional study

Abstract

Objectives: Dental clinics can harbor and transmit Methicillin-resistant Staphylococcus aureus (MRSA) which is a challenging antibiotic-resistant pathogen with global health implications. The aim of the study was to assess the prevalence, resistance patterns and biofilm formation by Staphylococcus aureus (S. aureus) isolated from dental patients and dental health care workers (DHCWs) .

Materials and methods: Two hundred nasal swab specimens were collected aseptically from 120 dental patients and 80 DHCWs across Egypt including Cairo, Giza, and Upper Egypt over a 12 –month period. The study incorporated a comprehensive analysis to identify MRSA isolates using disk diffusion test with cefoxitin, to confirm MRSA isolates by molecular detection of the mecA gene and the prevalence intercellular adhesion gene A and D (icaA and icaD) using Polymerase chain reaction assays, to evaluate the antimicrobial resistance profiles of S. aureus using Kirby-Bauer disk diffusion method, and to detect the qualitative and quantitative characteristics of the biofilm formation using Congo red agar plates and microtiter plate method respectively. Statistical package for social science was used for data analysis.

Results: Results were interpreted following the Clinical and Laboratory Standards Institute 2023 guidelines. S. aureus was identified in 47.1% of the collected Staphylococcus species with 66.6% of these S. aureus isolates carried mecA genes and identified as MRSA. The identification rate of icaA and icaD in MRSA isolates was significant compared to Methicillin-Sensitive Staphylococcus aureus (MSSA) isolates, with detection rates of 88.6% and 40.9% respectively. Regarding antimicrobial resistance patterns, all isolates were resistant to Penicillin (100%) with notable resistance to other antibiotics including Clindamycin (60.6%), Erythromycin (42.4%), and Gentamicin (24.2%). Biofilm formation ability was detected in 72.7% of the MRSA isolates with high incidence of strong and moderate biofilm formation in 93.1% of these isolates compared to MSSA isolates (50%).

Conclusions: The high MRSA colonization rates among DHCWs and patients, along with significant antibiotic resistance and biofilm-forming abilities, highlight the urgent need for regular screening and enhanced infection control measures in dental healthcare settings. Future research should aim to expand sampling and clarify more site selection criteria to better inform infection control strategies and improve generalizability.

Clinical relevance: Given the persistent threat of MRSA in dental settings, the implementation of rigorous infection control protocols and comprehensive antibiotic stewardship strategies is imperative to mitigate transmission risks and enhance patient safety.