Clinical MRSA Profiles Reveal Age- and Gender-Specific Transmission Dynamics in a Tertiary Care Hospital: High Burden in ICU Elderly and Emerging Community Patterns in Youth

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a devastating global health concern. Hypervirulent-strains are on the rise causing morbidities and mortalities worldwide. In tertiary care hospitals, critically-ill, invasive-procedures, pediatrics, and geriatrics are at risk. It is not clear how the strains specialized in humans in a clonal-genome. This study investigates the influence of age-, gender-, and source- (clinical, ICU vs. non-ICU)-specificity profiles in the evolution into hospital-associated (HA-MRSA) versus community-associated (CA-MRSA) lineages. Methods: 253 non-duplicate S. aureus isolates were obtained from May 2023 to March 2025). Patients were stratified by age and gender in ICU and non-ICUs. Standard microbiology methods and CLSI guidelines were used for identification and susceptibility testing, with cefoxitin and oxacillin disk diffusions and molecular diagnosis confirming MRSA. Mann-Whitney U and Chi-square tests assessed demographic distributions, clinical specimen sources, and MRSA/MSSA prevalence. Results: Of 253, 41.9% originated from ICUs (71% male, 29% female) and 58.1% from non-ICU wards (64% male, 36% female). In both settings, MRSA colonized the two extremes of age (10–29 and 70+) for males and females, with different mid-life peaks or declines by gender. However, the overall demographic distribution did not differ significantly between ICU and non-ICU groups (p = 0.287). Respiratory specimens constituted 37% and had the highest MRSA rate (42%), followed by blood (24.5%) and wounds (10.3%). In contrast, MSSA dominated wound (20.3%). Overall, 73.9% were resistant to cefoxitin and cefotaxime, whereas vancomycin, linezolid, daptomycin, and tigecycline remained highly effective. Younger non-ICU patients (10–29) had higher MSSA, whereas older ICU ones showed pronounced HA-MRSA profiles. By the virtue of methicillin-resistance, all MRSA were classified as multidrug resistance. Thus, MRSA colonization of the two extremes of life mostly in ICU seniors and the dominance of invasive MSSA and CA-MRSA patterns in non-ICU youth, imply early age- and gender-specific adaptations of the three lineages. Conclusion: MRSA colonizes both ICU and non-ICU populations at extremes of age gender-specificically. High β-lactam-resistance underscores the importance of robust stewardship and age- and gender-specific targeting in screening. These findings also indicate host- and organ-specificity in sequalae of MSSA, CA-MRSA, HA-MRSA evolutionary-dynamics emphasizing the need for continued surveillance to mitigate MRSA transmission and optimize patient outcomes in tertiary care settings.