CLINICAL AND MICROBIOLOGICAL CHARACTERIZATION OF ANTIMICROBIAL-RESISTANT GRAM-NEGATIVE PATHOGENS ISOLATED FROM HOSPITALIZED AND OUTPATIENT POPULATIONS

Abstract

Emergence of antimicrobial resistance in Gram-negative bacteria is a major threat to effective clinical settings, epically in that management where empirical use of antibiotics is common. Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae are among the most frequently isolated pathogens and clinically pathogens worldwide. These pathogens are frequently implicated in both hospital and community-acquired infections, including, wound infections, urinary tract infections (UTIs), blood stream infections, and severe infections in persons that have weak immunity. Current study has determined the antimicrobial susceptibility patterns of E. coli, P. aeruginosa, and K. pneumoniae isolated from 200 clinical that were processed in microbiology laboratory of the Department of Microbiology, Abbottabad University of Science and Technology. Bacterial isolation and identification were performed using standard microbiological techniques. Antimicrobial susceptibility testing was carried out using the Kirby–Bauer disc diffusion method on Mueller–Hinton agar, and results were interpreted according to clinical laboratory standards guidelines. Demographic and clinical data, including age, gender, hospitalization status, prior antibiotic use, and presence of indwelling medical devices, were analyzed. Statistical analysis was performed using the chi-square test, with a p-value < 0.05 considered statistically significant. Of the 200 samples analyzed, 168 (84%) yielded bacterial growth. E. coli was the most frequently isolated organism (44%), followed by P. aeruginosa (31%) and K. pneumoniae (25%). High levels of resistance were observed against commonly used antibiotics, with P. aeruginosa showing the highest proportion of multidrug-resistant isolates. Multidrug resistance was significantly associated with prolonged hospitalization, diabetes mellitus, prior antibiotic exposure, and the presence of indwelling devices (p < 0.05). The study demonstrates a substantial burden of multidrug-resistant E. coli, P. aeruginosa, and K. pneumoniae in clinical samples. P. aeruginosa exhibited the highest level of multidrug resistance, followed by K. pneumoniae and E. coli. These findings underscore the importance of routine antimicrobial susceptibility testing, rational antibiotic use, and strengthened antimicrobial stewardship programs to mitigate the spread of resistance