A typical hospital-acquired methicillin-resistant Staphylococcus aureus clone is widespread in the community in the Gaza strip

Abstract

Epidemiological data on community acquired methicillin-resistant-Staphylococcus aureus (CA-MRSA) carriage and infection in the Middle-East region is scarce with only few reports in the Israeli and Palestinian populations. As part of a Palestinian-Israeli collaborative research, we have conducted a cross-sectional survey of nasal S. aureus carriage in healthy children and their parents throughout the Gaza strip. Isolates were characterized for antibiotic susceptibility, mec gene presence, PFGE, spa type, SCCmec-type, presence of PVL genes and multi-locus-sequence-type (MLST). S. aureus was carried by 28.4% of the 379 screened children-parents pairs. MRSA was detected in 45% of S. aureus isolates, that is, in 12% of the study population. A single ST22-MRSA-IVa, spa t223, PVL-gene negative strain was detected in 64% of MRSA isolates. This strain is typically susceptible to all non-β-lactam antibiotics tested. The only predictor for MRSA carriage in children was having an MRSA carrier-parent (OR=25.5, P=0.0004). Carriage of the Gaza strain was not associated with prior hospitalization. The Gaza strain was closely related genetically to a local MSSA spa t223 strain and less so to EMRSA15, one of the pandemic hospital-acquired-MRSA clones, scarcely reported in the community. The rapid spread in the community may be due to population determinants or due to yet unknown advantageous features of this particular strain.

Figure 1. Molecular relatedness of ST22 isolates in this survey.

Dendrogram of all isolates corresponding to ST22, by deduction from PFGE patterns (see Methods), including MRSA SSCmec IV and V, MSSA and EMRSA-15 isolate as a reference strain.

Figure 2. Molecular characterization and relatedness of MRSA isolates carried by parent-child pairs.

Figure 3. Distribution of MLSTs among MRSA and MSSA isolates tested.

Black – MRSA, Grey- MSSA, striped – ST22.