Antimicrobial resistance in major bacterial and fungal pathogens in hospital-acquired infections from a tertiary care hospital in Lodhran, Pakistan.

Abstract

The distribution of antimicrobial resistance in major pathogens was analyzed in a tertiary care hospital of Lodhran, Pakistan. Altogether, 1910 patients diagnosed and treated at Shahida Islam Medical Complex Hospital from December 2023 to August 2025 were selected. The antimicrobial resistance of major bacterial and fungal pathogens was quantified, and logistic regression analysis was used to identify the risk factors for infection. Methicillin-resistant Staphylococcus aureus (MRSA) isolates retained susceptibility to vancomycin (58.3%), while ceftazidime/avibactam showed activity against Escherichia coli (80%), Klebsiella pneumoniae (82%), and Pseudomonas aeruginosa (78%). Vancomycin-resistant Enterococcus (VRE) demonstrated resistance to nearly all antibiotics. PCR confirmed TEM and SHV in 23/51 (45%) of E. coli isolates, while in K. pneumoniae TEM and SHV were each detected in 20/35 (56%). Among P. aeruginosa isolates, VIM, NDM, and OXA-48 were each present in 14/37 (37%). The mecA was found in 47/49 (95%) of S. aureus isolates (MRSA), vanA in 34/49 (70%) of S. aureus (VRSA), and vanA in 34/43 (80%) of Enterococcus isolates (VRE). MLST analysis of representative multidrug-resistant isolates identified ST131 (1/3, 33%) among E. coli, ST11 (1/3, 33%) and ST258 (1/3, 33%) among K. pneumoniae, ST175 (1/3, 33%) and ST233 (1/3, 33%) among P. aeruginosa, ST5 (1/3, 33%) and ST22 (1/3, 33%) among S. aureus, and ST17 (1/3, 33%) among Enterococcus spp. PCA revealed distinct clustering of species, with Gram-negatives overlapping, Gram-positives forming separate groups, and fungi clustering independently. Logistic regression identified age ≥65, ICU admission, comorbidities, prior antibiotic exposure, invasive procedures, and immunosuppressive therapy as significant AMR risk factors, while infection control and stewardship reduced risk (P < 0.05). This study demonstrates a high burden of antimicrobial resistance, primarily mediated by TEM and SHV β-lactamases in E. coli and K. pneumoniae, and by VIM, NDM, and OXA-48 carbapenemases in P. aeruginosa. Additionally, MRSA, VRSA, and VRE showed multidrug resistance. Effective infection control and antibiotic stewardship remain critical to limit the spread of resistant pathogens and to reduce hospital-acquired AMR risk.