Antibiotic Sensitivity of Multidrug Resistant Bacteria isolated among Patients Admitted to a Tertiary Care Centre in Southern Sri Lanka

Abstract

Multidrug-resistant bacteria, including extended-spectrum beta-lactamase (ESBL) producing Gram-negatives, are increasingly isolated in both community and hospital-acquired infections. Treatment of these infections is challenging because of the scarcity of effective antimicrobials and limited evidence of efficacy. Carbapenems and aminoglycosides are commonly used to treat these infections. Thus, this study was performed to determine in-vitro susceptibilities of different antibiotics against clinical isolates of ESBL-producing Gram-negative pathogens isolated in the Microbiology laboratory in Teaching Hospital, Karapitiya. A total of 157 clinical isolates of ESBL-producing Gram-negative bacteria were collected from patients admitted to Teaching Hospital, Karapitiya, from November 2021 to July 2022. Double disc synergy test was used to identify ESBL producers. Antibiotic sensitivity patterns of those isolates against different antibiotics including carbapenem and aminoglycosides were performed by disc diffusion test according to Clinical Laboratory Standard Institute (CLSI) guidelines. Collected data were analysed using SPSS -25 statistical software. The mean age of the patients was 49.4 years (n=157; SD± 20.8), ranging from newborn to 92 years. The majority (55.4%) were females. The ESBL Gram-negatives were predominantly isolated from urine at 40.1% (n=63), followed by sputum at 19.7% (n=31), and blood at 14.0% (n=22). Klebsiella spp (33.8%) and E. coli (27.4%) were the predominant isolates. The overall sensitivity of the ESBL producers against meropenem, ertapenem, and imipenem were 93.6%, 91.7%, and 90.5%, respectively. The sensitivity to ciprofloxacin and cotrimoxazole was 8.9% and 30.6% respectively. Of all, a majority (81.0%) showed sensitivity to amikacin in comparison to gentamicin (49.2%). Among the urinary pathogens, the majority (63.3%) were sensitive to nitrofurantoin whereas the majority showed resistance to nalidixic acid (88.9%) and norfloxacin (82.1%). Carbapenems, amikacin, and nitrofurantoin were better antibiotics in the treatment of infections caused by ESBL-producing Gram-negative bacteria. Therefore, the selection of the best antibiotic needs to be guided by an in-vitro sensitivity assay of the isolated pathogen.