Antibiotic Resistance and Genomic Diversity of Methicillin-Resistant Staphylococcus aureus Clonal Complex 45 Isolates...

Background/Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) causes hospital- and community-acquired infections. MRSA is a highly diverse strain that includes several epidemic clones, including CC45. A previous study conducted among MRSA isolates in Kuwait identified CC45 in two isolates in the early 2000s. This study provides an update on the prevalence and molecular characteristics of CC45 among MRSA isolates in Kuwait hospitals, during 2016-2022. Methods: A total of 13,276 MRSA isolates were collected during 2016-2022 and typed using antibiogram, DNA microarray, Staphylococcal protein A (spa) typing, pulsed-field gel electrophoresis (PFGE), and multi-locus sequence typing (MLST). Results: CC45 was detected in 87 (0.65%) of the 13,276 MRSA isolates. The isolates were resistant to fusidic acid (n = 71), erythromycin (n = 16), and inducible clindamycin resistance (n = 15). Twenty-one isolates were resistant to multiple antibiotics. Spa typing identified 19 types, with t362 (n = 35) and t132 (n = 27) as the dominant types. DNA microarray identified seven genotypes with CC45-MRSA-[IV + fus] (n = 36) and CC45-MRSA-[VI + fus] (n = 30) as the dominant types. MLST identified six sequence types (STs): ST7119, ST508, ST45, ST46, ST9548, and ST10699. PFGE clustered the isolates into two major types, A and B, with type A being the major type (n = 83), mostly consisting of CC45-MRSA-[IV + fus] isolates. The CC45-MRSA-[IV + fus] and CC45-MRSA-[VI + fus] genotypes were detected throughout the study period (2016-2022), whereas the other genotypes were detected less frequently. Conclusions: The CC45-MRSA circulating in Kuwait hospitals comprises genetically diverse isolates that may have originated from different sources. The emergence of multidrug resistance among the isolates poses challenges for therapy and infection prevention.