Antimicrobial Resistance Patterns in Bacterial Isolates from Hospital-Acquired Infections
Dhuha Abdullah Abbas, Alyaa Abdulhussein Alsaedi, Baraa Abdulameer Hadi, Mahmood Hameed Al-Safi
Abstract
Hospital-acquired infections (HAIs) is a important source of morbidity with mortality worldwide. The increasing prevalence from antimicrobial resistance (AMR) among HAI pathogens complicates empirical therapy and infection control. This study characterizes the antimicrobial resistance patterns of bacterial isolates recovered from HAIs at a tertiary-care hospital. We conducted a retrospective cross-sectional study of bacterial isolates obtained from patients with HAIs between January 1, 2024 and December 31, 2024. Clinical specimens (blood, urine, wound/tissue, respiratory secretions, and catheter tips) submitted to the microbiology laboratory were included if cultures met criteria for HAI. Species identification and antimicrobial susceptibility testing (AST) were performed using standard laboratory methods and interpreted according to CLSI/EUCAST guidelines. Data were analyzed for pathogen distribution, resistance rates to key antibiotic classes, multidrug resistance (MDR) prevalence, and trends by specimen type and ward. A total of 400 non-duplicate isolates from 380 patients met inclusion criteria. Gram-negative bacteria comprised 72% (n=288) of isolates; Gram-positive bacteria comprised 28% (n=112). The most common organisms were Escherichia coli (22%), Klebsiella pneumoniae (18%), Pseudomonas aeruginosa (12%), Acinetobacter baumannii complex (10%), Staphylococcus aureus (9%), and Enterococcus spp. (6%). Resistance to third-generation cephalosporins was observed in 56% of E. coli isolates and 62% of K. pneumoniae isolates. For carbapenems, resistance rates were 14% in E. coli, 24% in K. pneumoniae, 28% in P. aeruginosa, and 46% in A. baumannii. Extended-spectrum beta-lactamase (ESBL) phenotype was detected in 48% of Enterobacterales. Methicillin-resistant S. aureus (MRSA) accounted for 36% of S. aureus isolates. Overall MDR (resistance to ≥3 antibiotic classes) prevalence was 39%. Intensive care unit (ICU) isolates had significantly higher MDR rates (58%) compared to general wards (31%) (p<0.001). This study reveals high rates of resistance among common HAI pathogens, particularly Gram-negative organisms and ICU isolates. Strengthened antimicrobial stewardship, targeted infection control measures, and continual local surveillance are essential to optimize empirical therapy and limit AMR spread.