BackgroundCommunity-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a global healthcare problem. The purpose of this study was to characterize CA-MRSA clones and their distribution in Kuwait hospitals.MethodsIn total, 135 CA-MRSA isolates, carrying the SCCmec IV or V genetic elements, isolated in eight hospitals were characterized using antibiogram, pulsed-field gel electrophoresis, multilocus sequence typing, and carriage of genes for Panton-Valentine Leukocidin (PVL), capsular polysaccharides types (cap) 5 and 8, accessory genes regulators (agr), Staphylococcal enterotoxins (SE) and toxic shock syndrome toxin 1 (tst).ResultsThey were susceptible to vancomycin, teicoplanin and linezolid but resistant to kanamycin (62%), fusidic acid (42.2%), tetracycline (39.3%), erythromycin and clindamycin (21.5%), gentamicin (5.9%), streptomycin (6.7%), trimethoprim (5.9%), mupirocin (6.6%) and cadmium acetate (82.2%). They consisted of 10 pulsotypes with the majority belonging to PFGE type I (51.1%), type II (22.2%), type IV (13.3%) and type III (3.7%). They belonged to 10 sequence types (ST) comprising ST80 (51.1%), ST30 (22.2%), ST5 (14.1%), ST1 (4.45), ST6 (3.7%), ST88 (1.5%), ST834 (1.5%), ST8 (0.7%), ST46 (0.7%) and ST950 (0.7%). Genes for PVL, cap 8, cap 5 and agr III, agr I and agr II were detected in 61.5%, 77.3%, 20.7% and 62.2%, 17% and 8.1% of the isolates respectively. Nine (6.7%) isolates contained tst while 103 isolates were positive for SE genes with sei (63.0%), seg (41.5%) and sed (29.6%) as the common SE genes.ConclusionsST80-SCCmecIV was the most common CA-MRSA clone in Kuwait hospitals presenting new challenges for infection control.

A total of 29 meticillin-resistant Staphylococcus aureus (MRSA) isolates were obtained from 15 neonates and three healthcare workers (HCWs) in a neonatal intensive care unit (NICU) and special care baby unit (SCBU) and four patients in a medical ward of a Kuwait hospital between 10 and 30 April 2007. The isolates were characterized using antibiogram results, coagulase gene RFLP (coa-RFLP), PFGE, staphylococcal cassette chromosome mec (SCCmec) typing and multilocus sequence typing (MLST). All isolates were assessed for the carriage of PantonValentine leukocidin (PVL) and arginine catabolic mobile element (ACME) genes. The isolates belonged to three SCCmec types, six coa-RFLP types, six pulsotypes and six sequence types. One isolate was positive for PVL. None were positive for ACME. All MRSA isolates from the 15 neonates were phenotypically and genetically different from the MRSA isolates obtained from HCWs and those from patients in other wards. They were resistant to gentamicin, kanamycin and fusidic acid, had identical coa-RFLP and PFGE patterns, carried the type V SCCmec element and belonged to MLST sequence type ST97. The results showed the transmission of a rare clone of community-associated MRSA belonging to ST97 with the SCCmec-V genotype among neonates in a NICU and SCBU.

Four community-associated meticillin-resistant Staphylococcus aureus (CA-MRSA) isolates expressing high-level mupirocin resistance (MIC .1024 mg l "1 ) were isolated from four sites of a diabetic patient and characterized for the genetic location of their resistance determinants and typed using PFGE, staphylococcal cassette chromosome mec (SCCmec), the coagulase gene and multilocus sequence typing to ascertain their relatedness. The presence of genes for resistance to high-level mupirocin (mupA), tetracycline (tetK) and fusidic acid (far1), PantonValentine leukocidin (PVL), accessory gene regulators (agr) and capsular polysaccharide (cap) were detected in PCR assays. The isolates were resistant to kanamycin, streptomycin, tetracycline, fusidic acid and cadmium acetate, and harboured mupA, tetK, far1, PVL, agr3 and cap8. They had identical PFGE patterns and coagulase gene type, possessed the type IV SCCmec element and belonged to sequence type 80 (ST80). However, they had three different plasmid profiles: (i) 28.0 and 26.0 kb; (ii) 28.0, 21.0 and 4.0 kb; and (iii) 41.0 and 4.0 kb. Genetic studies located the resistance to tetracycline, fusidic acid and cadmium acetate on the 28 kb plasmid and mupA on the related non-conjugative 26 and 21 kb plasmids. One of the 21 kb mupirocin-resistance plasmids was derived from the~41 kb plasmid during transfer experiments. The emergence of high-level mupirocin resistance in the ST80-SCCmec IV MRSA clone demonstrates the increasing capacity of CA-MRSA clones to acquire resistance to multiple antibacterial agents. The presence of different plasmid profiles in genetically identical isolates creates difficulty in the interpretation of typing results and highlights the weakness of using plasmid analysis as the sole method for strain typing.

Methicillin-resistant Staphylococcus aureus (MRSA) belonging to clonal complex 361 (CC361-MRSA) is rare among patients’ populations globally. However, CC361-MRSA has been isolated with an increasing trend among patients in Kuwait hospitals since 2010. This study investigated the molecular characteristics of CC361-MRSA isolated from patients in Kuwait hospitals in 2016–2018 to understand their genetic relatedness and virulence determinants. Of 5,223 MRSA isolates investigated by DNA microarray, 182 (3.4%) isolates obtained in 2016 (N = 55), 2017 (N = 56), and 2018 (N = 71) were identified as CC361-MRSA. The CC361-MRSA isolates were analyzed further using antibiogram, spa typing and multi locus sequence typing (MLST). Most of the isolates were resistant to fusidic acid (64.8%), kanamycin (43.4%), erythromycin (36.3%), and clindamycin (14.3%) encoded by fusC, aphA3, and erm(B)/erm(C) respectively. Nine isolates (4.9%) were resistant to linezolid mediated by cfr. The isolates belonged to 22 spa types with t3841 (N = 113), t315 (N = 16), t1309 (N = 14), and t3175 (N = 5) constituting 81.3% of the spa types, four genotypes (strain types), CC361-MRSA-[V/VT + fus] (N = 112), CC361-MRSA-IV, WA MRSA-29 (N = 36), CC361-MRSA-V, WA MRSA-70/110 (N = 33) and CC361-MRSA-[V + fus] variant (N = 1). MLST conducted on 69 representative isolates yielded two sequence types: ST361 (11/69) and ST672 (58/69). All CC361-MRSA isolates were positive for cap8, agr1, and the enterotoxin egc gene cluster (seg, sei, selm, seln, selo, and selu). The tst1 was detected in 19 isolates. The immune evasion cluster (IEC) genes type B (scn, chp, and sak) and type E (scn and sak) were detected in 20 and 152 isolates, respectively. The CC361-MRSA circulating in Kuwait hospitals consisted of two closely related sequence types, ST361 and ST672 with ST672-MRSA [V/VT + fus] as the dominant genotype. The dissemination of these newly emerged clones and the emergence of linezolid resistance limits therapeutic options, as well as present significant challenges for the control of MRSA infections in Kuwait hospitals.

s e345 values were not influenced by oxacillin or vancomycin susceptibility patterns for S. aureus and enterococci, respectively (0.25 mg/L for total S. aureus and enterococci, MSSA, MRSA, VRS, and VRE). Resistance patterns noted were: tetracycline (see Table), ESBL-and fluoroquinolone resistance in Enterobacteriaceae (28.8, 33.7%, respectively), VRE (9.9%), MRSA (47.7%) and Acinetobacter spp. carbapenem (imipenem)-resistant (76.1%).