Journal of Preventive Medicine & Infectious Diseases

Abstract

Background: Serratia marcescens is a Gram-negative opportunistic pathogen linked to hospital-acquired infections and increasing multidrug resistance. Data on its resistance patterns in Pakistan, particularly car bapenem resistance, remain limited. This study assesses antimicrobial resistance trends of S. marcescens over seven years at a tertiary hospital in Rawalpindi.

Methods: A retrospective registry-based study was conducted at the Microbiology Department, Fauji Foun dation Hospital, Rawalpindi, from January 2017 to December 2023. Clinical isolates from patients aged 10–80 years were obtained using consecutive non-probability sampling. Standard microbiological techniques, including API 10S® (bioMérieux), were employed for identification of Serratia marcescens. Antimicrobial susceptibility testing was performed using the modified Kirby-Bauer disc diffusion method on Mueller-Hinton agar, by CLSI guidelines. Data were analyzed using Microsoft Excel 19.0. We identified the number of strains resistant to different antibiotics.

Results: A total of 108 S. marcescens isolates were identified, with a marked increase in incidence in 2022 (45.4%) and 2023 (28.7%). Most isolates were from the Medicine (39.8%), Surgical (31.5%), and ICU (21.3%) wards. Pus (47.2%), blood (20.4%), and bronchial washings (12.0%) were the most common clinical samples. High resistance was observed against amoxicillin-clavulanate (97.3%), ampicillin (94.2%), and ceftazidime (58.2%). ciprofloxacin showed moderate resistance (43.5%). Lower resistance rates were found for tigecy cline (5.3%), minocycline (12.8%), meropenem (24.6%), and imipenem (25.9%).

Conclusion: The study shows rising multidrug resistance in S. marcescens, including emerging carbapenem resistance, threatening empirical treatment. Strengthened surveillance and antimicrobial stewardship are essential to limit spread in healthcare settings.