Molecular Characterization of Methicillin Resistant Staphylococcus aureus in West Bank-Palestine

Methicillin-resistant (MRSA) is a public health threat and a major cause of hospital-acquired and community-acquired infections. This study aimed to investigate the genetic diversity of MRSA isolates from 2015 to 2017 and to characterize the major MRSA clones and anti-biogram trends in Palestine. Isolates were obtained from 112 patients admitted to different hospitals of West Bank and East Jerusalem, originating from different clinical sources. Antibiotic susceptibility patterns, staphylococcal chromosomal cassette (SCC ) typing, and protein A ( ) typing were determined. Also, a panel of toxin genes and virulence factors was studied, including: Panton-Valentine Leukocidin (PVL), ACME- A, Toxic Shock Syndrome Toxin-1 (TSST-1), and Exfoliative Toxin A (ETA). Of the 112 confirmed MRSA isolates, 100% were resistant to all β-lactam antibiotics. Resistance rates to other non- β-lactam classes were as the following: 18.8% were resistant to trimethoprim-sulfamethoxazole, 23.2% were resistant to gentamicin, 34.8% to clindamycin, 39.3% to ciprofloxacin, and 63.4% to erythromycin. All MRSA isolates were susceptible to vancomycin (100%). Of all isolates, 32 isolates (28.6%) were multidrug- resistant (MDR). The majority of the isolates were identified as SCC type IV (86.6%). The molecular typing identified 29 types representing 12 MLST-clonal complexes (CC). The most prevalent types were: type t386 (CC1)/(12.5%), type t044 (CC80)/(10.7%), type t008 (CC8)/(10.7%), and type t223 (CC22)/(9.8%). PVL toxin gene was detected in (29.5%) of all isolates, while ACME- gene was present in 18.8% of all isolates and 23.2% had the TSST-1 gene. The two most common types among the TSST-1positive isolates were the type t223 (CC22)/(Gaza clone) and the type t021 (CC30)/(South West Pacific clone). All isolates with the type t991 were ETA positive (5.4%). USA-300 clone ( type t008, positive for PVL toxin gene and ACME- genes) was found in nine isolates (8.0%). Our results provide insights into the epidemiology of MRSA strains in Palestine. We report a high diversity of MRSA strains among hospitals in Palestine, with frequent SCC type IV carriage. The four prominent clones detected were: t386-IV/ CC1, the European clone (t044/CC80), Gaza clone (t223/CC22), and the USA-300 clone (t008/CC8).