ANTIMICROBIAL RESISTANCE TRENDS AMONG BLOODSTREAM PATHOGENS IN A TERTIARY CARE SETTING, PESHAWAR

ABSTRACT OBJECTIVES This study aimed to identify common pathogens isolated from blood cultures and evaluate their antimicrobial resistance patterns. METHODOLOGY This retrospective observational study was conducted at Rehman Medical Institute, Peshawar, from January to December 2024. All positive blood cultures during the study period were processed using standard microbiological techniques and the Vitek 2.0 system. Antimicrobial susceptibility testing was performed according to Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2024 guidelines. Organisms were categorized as per standard resistance classification. Data were analyzed in SPSS v27, with p<0.05 considered significant. RESULTS Among 569 blood cultures, the most common isolates were Staphylococcus aureus (27.9%), Salmonella (25%), and Klebsiella (13.8%). Organism distribution varied significantly with age (p<0.001). Most S. aureus were methicillin-resistant S. aureus (MRSA, 88.6%), with no vancomycin resistance. Enterococcus and Streptococcus showed minimal resistance except to erythromycin. Salmonella included 31% multidrug-resistant (MDR) and 55.6% extensively drug-resistant (XDR) strains, with XDR significantly more common in S. typhi, pediatric patients, and age groups (p<0.001, 0.001, 0.2). Highly resistant Klebsiella were frequent: extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-E) 83.3% and carbapenem-resistant Enterobacteriaceae (CRE) 62.8%, with ESBL significantly associated with age (p 0.04). In Escherichia coli, 69.4% were ESBL and 12.2% were CRE, with ward-specific variation in CRE (p=0.002). Serratia showed ESBL (66.6%) and CRE (50%), with CRE more frequent in males (p=0.02). About 84% of Acinetobacter strains were difficult-to-treat resistance (DTR) strains, significantly associated with intensive care unit (ICU) patients and middle-aged individuals (p<0.03, 0.04). Pseudomonas showed lower resistance, with a 23.5% DTR, strongly associated with ICU (p=0.006). CONCLUSION Highly resistant pathogens were found in BSI, particularly MRSA, XDR Salmonella, and ESBL/CRE-producing Klebsiella and Serratia. Significant associations with patient age and hospital location underscore the urgent need for continuous surveillance, strengthened infection control, and robust antimicrobial stewardship programs.