Screening of Extended Spectrum Beta Lactamase (ESBL) Producing Citrobacter freundii in Clinical and Animal Samples Isolated from Lagos, Nigeria

The emergence in recent times of extended-spectrum beta-lactamases (ESBLs) producing pathogenic bacteria poses a serious antibiotic management problem. Citrobacter sp., though less commonly isolated are regarded as an emerging nosocomial multidrug-resistance (MDR) pathogen. The main objective of this study is to screen for ESBLs in Citrobacter freundii isolates. Over a period of two months, 50 clinical samples were collected from patients attending tertiary health institutions in Lagos state, and 45 animal samples were collected from cattle and poultry farms giving a total of 95 samples. The samples were cultured by standard procedures. Isolates were identified using standard methods. Antimicrobial susceptibility testing was performed on all isolates by Clinical and Laboratory Standards Institute (CLSI) guidelines. The isolates were further screened for ESBL production using double disk diffusion synergy techniques. Four of the 48 Isolates were positive for Citrobacter freundii (8.33%). Other bacterial pathogens identified included Citrobacter koseri (14.58%), Escherichia coli (33.33%), E. coli O157 (10.42%), Klebsiella oxytoca (20.83%), Staphylococcus spp. (12.5%), and Pseudomonas aeruginosa (2.08%). Antimicrobial susceptibility testing revealed that high antibiotic resistance was observed in ceftazidime (100%), cefuroxime (100%), augmentin (100%), and low in ciprofloxacin (50%). Susceptibility was observed in gentamicin (100%), nitrofurantoin (100%), cefixime (75%) and ofloxacin (75%). It was observed that none of the strains of Citrobacter freundii isolates showed ESBL production. Gentamicin and nitrofurantoin were found to be effective drugs for the Citrobacter freundii-associated infections.