Prevalence and Antimicrobial Susceptibility of Klebsiella Species in Clinical Specimens of Indoor and Outdoor Patients at a Tertiary Care Hospital, Rawalpindi, Pakistan

Background: Klebsiella spp. are Gram-negative, non-motile, capsulated rods that function as opportunistic pathogens responsible for a broad spectrum of nosocomial infections, including urinary tract infections (UTIs) and respiratory tract infections. The escalating prevalence of multidrug resistant (MDR) strains and Extended Spectrum Beta-Lactamase (ESBL) producing isolates constitutes a critical global public health challenge, particularly in developing nations such as Pakistan. Objective: To determine the prevalence and antimicrobial susceptibility pattern of Klebsiella species isolated from clinical specimens of indoor and outdoor patients at a tertiary care hospital in Rawalpindi, Pakistan. Methods: A cross-sectional descriptive study was conducted over three months at the Microbiology Laboratory, Holy Family Hospital, Rawalpindi. A total of 143 consecutive non-probability clinical isolates of Klebsiella spp. were obtained from various specimen types. Identification was confirmed by Gram staining and standard biochemical tests. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method on Mueller-Hinton agar, interpreted according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: Klebsiella pneumoniae was the predominant isolate. Urine was the most frequent specimen source (44.1%), followed by pus (18.2%) and wound swabs (16.8%). Female patients (55.2%) showed higher prevalence than males (44.8%); inpatients contributed more isolates (62.2%) than outpatients (37.8%). Highest resistance was recorded against amoxicillin-clavulanate (98%), cefotaxime (97%) and cefixime (96.7%). Colistin demonstrated the greatest efficacy (96.6% susceptibility), followed by gentamicin (82%), amikacin (78.1%) and tigecycline (75.5%). Conclusion: K. pneumoniae isolates at this tertiary care centre exhibit alarmingly high resistance to commonly prescribed beta-lactam antibiotics. Colistin and aminoglycosides remain the most active agents. Continuous antimicrobial surveillance and stringent antibiotic stewardship policies are urgently required. Keywords: Klebsiella pneumoniae; antimicrobial susceptibility; antibiotic resistance; ESBL; multidrug resistance; nosocomial infections; Pakistan