New Sequence Types of Staphylococcus aureus Strains Isolated from Hospitals and Community Settings in Southern Iran

Background: Staphylococcus aureus is a significant bacterial pathogen globally recognized as the primary cause of numerous uncomplicated skin infections and severe invasive infections. The emergence of methicillin-resistant S. aureus (MRSA) poses a serious threat, leading to severe infections in both hospitals and community settings. Objectives: The aim of this study was to identify antibiotic resistance patterns and perform molecular classification of S. aureus strains isolated from both hospital and community settings in southern Iran. Methods: In this cross-sectional study conducted in Bandar Abbas between 2020 and 2021, a total of 156 clinical strains of S. aureus were collected. Antibiotic susceptibility was determined using the disk-diffusion agar method. The presence of the pvl gene, Sccmec types, and Agr group was identified through PCR analysis. Additionally, Multilocus sequence typing (MLST) was performed on selected isolates. Results: The study identified 156 strains, with 79 obtained from inpatients and 77 from outpatients, sourced from clinical samples. Among these isolates, 70 (44.8%) were classified as MRSA. The highest resistance was noted against azithromycin (83%), while the lowest resistance was observed for linezolid (5%) and gentamicin (7%). The presence of the pvl gene was detected in isolates from both hospital and community sources. Significant differences were noted in the occurrence of agr I and agr III genes between hospital and community isolates. Sccmec III was more predominant than other SCCmec types. Furthermore, MLST analysis revealed the presence of five distinct novel sequence types (STs): ST8634, ST8640, ST8650, ST8651, and ST8652. Conclusions: The findings indicate that the potential spread of hospital-acquired S. aureus strains to the community and vice versa poses a significant public health risk. This underscores the urgent need for robust infection control strategies and the identification of potential environmental and hospital sources of resistant strains, particularly MRSA strains.