Molecular and Source-Specific Profiling of Hospital Staphylococcus Aureus Reveal Dominance of Skin Infection and Age-Specific Selections in Pediatrics and Geriatrics

The changing epidemiology of Staphylococcus aureus has created several gaps in its population structure and emergence of strains. Two global shifts in the aftermath of the past methicil-lin-resistant S. aureus (MRSA) pandemic are: a rise in healthcare-associated infections and evolu-tion of cutaneous and soft tissue infections with high morbidities and mortalities. Furthermore, bitter lessons from COVID-19 showed S. aureus necrotizing-pneumonia and skin conditions ag-gravating Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) and Monkeypox manifestations. Limited data and paucity of high-quality evidence exist for many key clinical questions. Using clinical microbiology, molecular characterization, hospital data on age and in-fection sites, and antibiograms, we have investigated S. aureus infection patterns. We showed that age-specific distribution in both intensive care unit (ICU) and non-ICU revealed highest infection rates (94.7%) in senior-patients >50 years; most were MRSA (81.99%). However, specific distribu-tions of geriatric MRSA and MSSA rates were 46.5% and 4.6% in ICU and 35.48% and 8.065% in non-ICU, respectively. Intriguingly, age groups 0-20 years showed uniquely similar MRSA pat-terns in ICU and non-ICU patients (13.9%, 9.7%, respectively) and MSSA in ICU (11.6%). In age groups 20-50 years, MRSA were 2-fold in non-ICU (35%) than ICU (18.6%). Interestingly, highly significant association was found between infection-site and age-groups (P-value .000). Skin in-fections remained higher in all ages; pediatrics 32.14%, adults 56%, and seniors 25% while res-piratory infections were lower in pediatrics (14.3%) and adult 17%), and highest in seniors (38%). Blood and “other” sites in pediatrics recorded (28.6%; 25%, respectively), slightly lower in adults (18.6%; 8.6%) and seniors (14%); 22.8%), respectively. Further, significant association existed between infection-site and MRSA (Chi-Square Test, P-value .002). The common cutaneous infec-tions across all age-groups and the significant association of MRSA to geriatric-respiratory infec-tions have a high potential for skin-carriage as reservoir for endogenous infection. The similar frequencies of both lineages in youth in all settings imply MSSA-carriage as potential evolutionary origins for MRSA. These findings have important clinical implications for strategic planning in patient management and S. aureus control particularly in age-specific infections and vigilance for potential viral coinfections.