Molecular analysis and susceptibility patterns of methicillin-resistant Staphylococcus aureus strains causing community- and health care-associated infections in the northern region of Palestine

Abstract

Community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is a major global problem. This study attempted to investigate the prevalence of nasal carriage of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) strains among 360 healthy university students at An-Najah National University, Palestine. For the purpose of comparing the staphylococcal cassette chromosome methicillin resistant determinant (SCCmec) type of MRSA, 46 clinical MRSA isolates were also included in this study. Susceptibility testing was performed by the disc diffusion method. The genetic association of MRSA isolates was investigated by SCCmec typing. A selected number of isolates were also used to amplify and sequence mecA. Nasal carriage of S aureus was found in 86 of 360 students (24%). MRSA accounted for 9% of S aureus isolates. All 86 strains of S aureus were sensitive to vancomycin. Resistance to penicillin G, amoxicillin/clavulanic acid, ciprofloxacin, erythromycin, and clindamycin was found in 98%, 93%, 33%, 23%, and 12% of the isolates, respectively. Resistance rates of the MRSA isolates were as follows: 100% resistant to penicillin G and amoxicillin/clavulanic acid, 96% to ethromycin, 52% to clindamycin, and 48% to ciprofloxacin. No vancomycin-resistant isolates were identified. In our study, nearly half (52%) of the MRSA isolates belonged to SCCmec types IVa and V. However, SCCmec types II and III are represented by 48%, whereas SCCmec type I was completely absent. The findings of this study indicate the existence of SCCmec type IVa in both student nasal carriers and health care settings. This emphasizes the need for implementation of a revised set of control measures in both settings. Moreover, the rational prescription of appropriate antibiotics should also be considered.