Abstract
Background: Methicillin-resistant Staphylococcus aureus (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.Methodology: 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 mec (SCCmec) typing, and Staphylococcus aureus protein A (spa) typing were determined. Also, a panel of toxin genes and virulence factors was studied, including: Panton-Valentine Leukocidin (PVL), ACME-arcA, Toxic Shock Syndrome Toxin-1 (TSST-1), and Exfoliative Toxin A (ETA).Results: 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 SCCmec type IV (86.6%). The molecular typing identified 29 spa types representing 12 MLST-clonal complexes (CC). The most prevalent spa types were: spa type t386 (CC1)/(12.5%), spa type t044 (CC80)/(10.7%), spa type t008 (CC8)/(10.7%), and spa type t223 (CC22)/(9.8%). PVL toxin gene was detected in (29.5%) of all isolates, while ACME-arcA gene was present in 18.8% of all isolates and 23.2% had the TSST-1 gene. The two most common spa types among the TSST-1positive isolates were the spa type t223 (CC22)/(Gaza clone) and the spa type t021 (CC30)/(South West Pacific clone). All isolates with the spa type t991 were ETA positive (5.4%). USA-300 clone (spa type t008, positive for PVL toxin gene and ACME-arcA genes) was found in nine isolates (8.0%).Conclusions: 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 SCCmec 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).
Highlights
Methicillin-resistant Staphylococcus aureus (MRSA) is an important bacterial pathogen in both community and healthcarerelated settings in different parts of the world
Defining which virulence factors a strain may harbor is important for understanding the virulence of the strain, and for studying the epidemiology of different common clones. Among these are: Panton-Valentine Leukocidin toxin (PVL); a pore-forming cytotoxin that can highly cause leukocyte destruction and tissue necrosis [14], Toxic Shock Syndrome Toxin-1 (TSST-1); a superantigen that can mediate fever, hypotension, rash, multi-organ dysfunction, and lethal shocks [15], Exfoliative Toxin A (ETA); a toxin that can lead to hydrolysis of the superficial skin layers leading to cutaneous infections and staphylococcal scalded skin syndrome (SSSS) [16] and arcA; a surrogate marker for Arginine Catabolic Mobile Element (ACME) I
From November 2015 to July 2017, a total of 112 MRSA isolates were collected from major hospitals in the West Bank-Palestine
Summary
Methicillin-resistant Staphylococcus aureus (MRSA) is an important bacterial pathogen in both community and healthcarerelated settings in different parts of the world. Methicillin resistance is caused by an alteration in the penicillin-binding protein (PBP2a) which has a lower affinity to the β-lactam antibiotics; including: all penicillins, all cephalosporins (except the fifth generation ceftaroline), and carbapenems [6, 7] It is encoded by the mecA gene carried on a staphylococcal chromosomal cassette (SCCmec).; the therapeutic options of MRSA strains are lowered and limited. Defining which virulence factors a strain may harbor is important for understanding the virulence of the strain, and for studying the epidemiology of different common clones Among these are: Panton-Valentine Leukocidin toxin (PVL); a pore-forming cytotoxin that can highly cause leukocyte destruction and tissue necrosis [14], Toxic Shock Syndrome Toxin-1 (TSST-1); a superantigen that can mediate fever, hypotension, rash, multi-organ dysfunction, and lethal shocks [15], Exfoliative Toxin A (ETA); a toxin that can lead to hydrolysis of the superficial skin layers leading to cutaneous infections and staphylococcal scalded skin syndrome (SSSS) [16] and arcA; a surrogate marker for Arginine Catabolic Mobile Element (ACME) I. 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
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