Seasonal and hospital settings variations in antimicrobial resistance among clinical isolates from cardiac patients: insights from a 7-Year study.

Background: Antimicrobial resistance (AMR) is a growing global health challenge, particularly in specialized tertiary care settings. Despite its significance, data on the effects of seasonal variations, demographics, and healthcare settings on AMR in Pakistan are scarce.

Aim: This study aimed to evaluate the prevalence and resistance patterns of AMR and identify the key contributing factors at a cardiac hospital in Faisalabad from 2012 to 2019 to inform targeted infection control strategies.

Methodology: This retrospective cross-sectional analysis of 3,035 patient records adhered to STROBE guidelines. AMR profiles, including the multiple antibiotic resistance (MAR) index and antibiotic resistance genes (ARGs), were examined in relation to seasonality, hospital settings, and patient demographics.

Results: This study identified Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli as the most prevalent pathogens, with S. aureus and K. pneumoniae classified among the ESKAPE group (Enterococcus faecium, S. aureus, K. pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.). Isolation rates were higher in inpatients (IPs) than outpatients (OPs), with peak occurrences in autumn and winter among IPs and in spring among OPs. Age and sex significantly influenced pathogen isolation rates. The multiple antibiotic resistance (MAR) index was highest for S. aureus isolates between 2017 and 2019, which showed complete resistance to vancomycin and oxacillin. Key resistance genes mecA, vanA, tetM, and aph(3') were frequently co-detected in S. aureus. Polymyxin B and colistin remained the most effective antibiotics against multidrug-resistant (MDR) strains.

Conclusion: These findings highlight the critical need for year-round AMR surveillance, with an enhanced focus during seasonal peaks, particularly for high-risk IPs in winter and autumn. Implementing localized antimicrobial stewardship programs (ASPs) and robust infection control measures is essential to reduce the AMR burden and curb its spread in inpatient settings, especially in resource-constrained healthcare systems, such as Pakistan.