Evaluation of the Effectiveness of Selected Antibiotics Against Bacterial Isolates Obtained from Clinical Samples in Tarhuna General Hospital and Private Clinics in Tarhuna City, Libya

Abstract

Antimicrobial resistance (AMR) is a critical global public health threat, exacerbated in regions with limited surveillance data. In Libya, information on local antimicrobial susceptibility patterns, particularly in semi-urban areas like Tarhuna, is scarce. This data deficit complicates the formulation of effective evidence-based empirical antibiotic therapies. This study aimed to evaluate the in-vitro efficacy of selected antibiotics against bacterial isolates from clinical samples in Tarhuna, Libya. The primary objective was to characterize local AMR patterns to inform and guide clinical prescribing practices. A descriptive cross-sectional, laboratory-based study was conducted on 78 bacterial isolates obtained from diverse clinical specimens (urine, blood, wound swabs, respiratory samples) at Tarhuna General Hospital and associated private clinics. Bacterial identification was performed using standard microbiological protocols. Antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method, with interpretation based on the latest Clinical and Laboratory Standards Institute (CLSI) guidelines. Resistance profiles were analyzed using descriptive and inferential statistics. The most frequently isolated pathogen was Escherichia coli, predominantly from urine specimens (n=24/78), confirming its role as the leading uropathogen. A significant proportion of patients (65.4%) reported recent antibiotic use. Gram-negative isolates, particularly Klebsiella pneumoniae and Pseudomonas aeruginosa, demonstrated extensive resistance to multiple antibiotic classes, including penicillins, fluoroquinolones, and macrolides, indicating the circulation of multidrug-resistant (MDR) strains. However, urinary E. coli isolates retained high susceptibility to Nitrofurantoin (85.7%). Among Gram-positive isolates, all Staphylococcus aureus strains were 100% susceptible to Vancomycin, and Streptococcus pyogenes remained 100% susceptible to Penicillin. This study reveals a high burden of antimicrobial resistance among clinical isolates in Tarhuna, especially concerning Gram-negative pathogens. The findings underscore the diminished efficacy of several empirically used antibiotics and highlight the critical need for localized surveillance to guide rational antibiotic use. The data strongly support the implementation of routine antibiotic susceptibility testing and antimicrobial stewardship programs to optimize patient outcomes and mitigate the further spread of resistance in this region.