DefinePK

Abstract

Antimicrobial resistance (AMR) in bloodstream infections (BSIs) presents a critical threat to global health, complicating treatment and increasing mortality. This retrospective, cross-sectional study characterized AMR patterns in bacterial isolates from a tertiary care hospital in Pakistan. Standard microbiological methods were used to identify isolates from blood cultures, and antimicrobial susceptibility testing was performed via Kirby-Bauer disc diffusion against a comprehensive panel of antibiotics, following CLSI 2024 guidelines. The results revealed high rates of multidrug resistance among key pathogens. Gram-positive isolates, particularly methicillin-resistant Staphylococcus aureus (MRSA), showed significant resistance to beta-lactams and macrolides (>80%), though remained largely susceptible to vancomycin (85%), linezolid (88%), and chloramphenicol (82%). Gram-negative isolates exhibited even more alarming resistance, with high rates to carbapenems (e.g., 83% for meropenem), third-generation cephalosporins (98–100%), and fluoroquinolones (60%). Despite this, colistin (85% susceptible) and tigecycline (91% susceptible) retained efficacy against most Gram-negative isolates. These findings underscore a severe and evolving AMR landscape in BSIs within the studied region, emphasizing the urgent need for robust antimicrobial stewardship and evidence-based empirical therapy. Sustained surveillance and prudent antibiotic use are essential to mitigating further resistance spread and guiding clinical practice