Abstract
Objective Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main causative agents of nosocomial infections that has posed a major threat to those with compromised immune systems such as nursing home residents. The aim of this study was to determine the rates of MRSA strains and the types of Staphylococcal Cassette Chromosome mec (SCCmec)in nursing homes in Saudi Arabia. Methods A total of 188 nasal swabs were collected from the residents and nursing staff in two nursing homes in Riyadh, Saudi Arabia. All MRSA isolates were tested for antimicrobial susceptibility and analyzed for mecA and SCCmec typing by multiplex PCR assay. Detection of the Panton–Valentine leukocidin (PVL) gene was also tested in all positive MRSA isolates by multiplex PCR using specific primers. Results Among the 188 collected nasal swabs (105 males and 83 females), MRSA colonization rate was 9.04% (11 (5.85%) females and 6 (5.71%) males). About 47% of MRSA were multidrug resistant (MDR) as acquired resistance to beta-lactam, macrolide, and aminoglycoside antibiotics. However, all the MRSA isolates showed susceptibility to vancomycin, tigecycline, and linezolid. All the MRSA isolates (n = 17) were mecA-positive with the SCCmec IVc (n = 7, 41.18%) as the most common SCCmec type followed by SCCmec V (n = 5, 29.41%) and SCCmec IVa (n = 2, 11.76%). The remaining isolates (n = 3) were nontypeable (17.65%). In addition, the PVL toxin gene was only detected in four of the male samples. Conclusion MRSA nasal colonization is a common incident among nursing home residents. The prevalence of community-associated (CA) MRSA (SCCmec IV and V) was more common than hospital-associated (HA) MRSA in our study samples. It is crucial to investigate such rate of incidence, which is a key tool in preventive medicine and would aid in determining health policy and predict emergent outbreaks.
Highlights
Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), is one of the main nosocomial pathogens associated with morbidity and mortality in both hospital and community settings [1]
S. aureus isolates have gained resistance to methicillin due to the Staphylococcal cassette chromosome Staphylococcal Cassette Chromosome mec (SCCmec) genetic element integrated into S. aureus genomic chromosomal DNA downstream the orfX gene [8]. is cassette contains the methicillin resistance gene, which is responsible for resistance to antibiotics such as methicillin, Canadian Journal of Infectious Diseases and Medical Microbiology penicillin, and other penicillin-like antibiotics and additional antibiotic resistance determinants [8]
Identification of methicillin resistance strains was confirmed by the detection of the mecA gene in a multiplex PCR
Summary
Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), is one of the main nosocomial pathogens associated with morbidity and mortality in both hospital and community settings [1]. E prevalence of MRSA in nursing homes varied substantially from 1% to 23% between countries in Europe [3]. Nursing homes have been denoted to increase MRSA transmission and infection due to their propensity to admit old-age residents with premorbid conditions and weakened immune systems [4,5,6]. A 2005 cross-sectional survey carried out by a Belgian cohort demonstrated that, on average, 19% of the screened nursing home residents were MRSA carriers [7]. S. aureus isolates have gained resistance to methicillin due to the Staphylococcal cassette chromosome SCCmec genetic element integrated into S. aureus genomic chromosomal DNA downstream the orfX gene [8]. Studies have proven a strong correlation between MRSA strains and their accrued resistance to commonly used groups of antibiotics such as tetracycline, fluoroquinolones, aminoglycosides, chloramphenicol, and macrolides [9]
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