Prevalence of Extended-Spectrum Beta- Lactamase-Producing Gram-Negative Pathogens

Abstract

Aim: This study determined the prevalence of extended spectrum β-lactamase (ESBL) producing Gram negative bacilli (GNB) and its genetic variants in clinical infections. Method: A total of 359 non-duplicate GNB were recovered from various clinical samples which were aseptically collected and processed following standard microbiological methods. Antibiotic susceptibility testing was carried out by standard disk diffusion method. ESBLs producers were confirmed by combination disk test and their genetic variants determined by polymerase chain reaction-based protocols. Results: Among 359 GNB, 94 (26.2%) produced ESBL which were mainly distributed across genera as Citrobacter (n=27; 28.7%), Escherichia (n=25; 26.6%), Klebsiella (n=14; 14.9%) Enterobacter (n=12; 12.8%) and Proteus (n=5; 5.3%). Urine was the main source of ESBL producers (n-35; 37.2%) but ESBL production was most prevalent among isolates from sputum (35.7%). Among bacterial species, Klebsiella pneuminiae had the highest prevalence of ESBL- producing phenotypes (44.8%), followed by Enterobacter cloacae (38.5%), Citrobacter freundii (37.7%), Enterobacter aerogenes (36.8%) and Escherichia coli (29.8%). Seventeen bacteria (19.8%) had single ESBL genes while 69 (80.2%) had multiple genes of which 24 harboured blaTEM, blaSHV and blaCTX-M, 40 harboured blaCTX-M and blaTEM, three haboured blaCTX-M and blaSHV and two haboured blaTEM and blaSHV. Among the ESBL-producing strains, blaCTX-M was the most common harboured gene (74; 78.7%), closely followed by blaTEM (72; 76.6%). Conclusion: This study reveals a high prevalence of ESBL-producing bacteria which could complicate antibiotic treatment of clinical infections. There is a need for continuous antibiotic resistance surveillance to inform improved antibiotic stewardship and infection prevention and control.