Phenotypic detection of Extended-spectrum â-lactamases (ESBLs) among Enterobacteriaceae and Pseudomonas aeruginosa from Mubi, Adamawa State, Nigeria

Abstract

Background: Extended-Spectrum â-Lactamases (ESBLs) are group of enzymes produced by bacterial species which enable them to withstand the effect of cephalosporin antibiotics. They are mostly reported among Enterobacteriaceae and other Gram-negative bacteria especially Pseudomonas aeruginosa.
Method: One hundred clinical samples comprising of urine, high vaginal swab (HVS), sputum, stool, semen and wound swab were analysed for bacterial growth. Bacterial species isolated were subjected to antibiotic susceptibility testing and phenotypic extended-spectrum â-lactamase production (ESBL).
Result: Only 62(62.0%) of the clinical samples yielded bacterial growth which belonged to eight (8) genera. Escherichia coli (35.5%) was the most predominant, followed by P. aeruginosa (16.1%), while the least was P. mirabilis (1.6%). Extended-spectrum â-lactamases (ESBLs) was observed in 27/62 isolates, an overall prevalence of 43.5% with a predominance of E. coli (40.7%), followed by P. aeruginosa (22.2%). Although the number of non-ESBL isolates (35) was more than that of ESBL isolates (27%) but with no statistical difference (P=0.703). The antimicrobial susceptibility profile of all the isolates showed that 61(98.4%) and 56(90.3%) of the isolates were resistant to the â-lactam antibiotics, ceftriaxone and cefpodoxime respectively and were variable to other antibiotics. All the ESBL producers were found resistant (100%) to ceftriaxone and cefpodoxime (all cephalosporins). Also, all ESBL producing P. mirabilis, K. pneumoniae and P. agglomerans were found resistant (100%) not only to cephalosporins antibiotics, but also to other classes of antibiotics. However, resistance to all fluoroquinolones (sparfloxacin, ciprofloxacin, perfloxacin and ofloxacin) and gentamycin was moderately low especially among ESBL producing E. coli and P. aeruginosa, while ESBL producing K. pneumoniae was susceptible to the afore mentioned antibiotics.
Conclusion: The finding of this study is worrisome considering the fact that most of the ESBLs strains exhibit MDR phenotype. This constitutes a threat to therapy not only in the hospital environment but also in the community.

Keywords: Phenotypic, ESBLs, Enterobacteriaceae, Mubi