Phenotypic and genotypic detection of extended spectrum β-lactamases among Escherichia coli and Klebsiella pneumoniae isolates from type 2 diabetic patients with urinary tract infections|
Elmi, Souad Youssouf Kani; Ashour, Medhat Saber; Alsewy, Fathy Zakaria & Azzam, Nashwa Fawzy Abd El Moez
Background: T2DM patients are more likely to have UTIs caused by resistant organisms such as ESBLs producing bacteria.
Challenging reliable identification and prompt characterization of in-vitro susceptibilities of these bacteria are the first steps
of deciding the appropriate antimicrobial therapy for UTIs caused by them.
Objectives: To isolate and identify E. coli and K. pneumoniae from urine of T2DM patients with UTIs, to determine antibiotic
resistance pattern among isolates, and to identify ESBLs production phenotypically and genotypically.
Material and method: All samples were cultured on Cystine-Lactose-Electrolyte-Deficient Agar medium (CLED) by using
calibrated loop. Growth of 100 colonies or more, i.e. 105 colony forming units (CFU)/mL urine was considered as significant
bacteriuria. Isolation and identification were done according to standard method. All isolates were tested for antibiotic
susceptibility testing by the disc diffusion method according to CLSI guidelines. Phenotypic detection of ESBLs was done
by double-disk synergy test. Genotypic detection of blaTEM, blaSHV and blaCTX-M genes by using PCR.
Results: Results of this study showed that E. coli and K. pneumoniae were the dominant bacterial isolates, they constituted 103
(91.2%) out of 113 urine isolates. E. coli (58. 4%) K. pneumoniae (32.7%), Enterococcus spp. (4.4%), Proteus spp. (2.7%) and Pseudomonas
spp. (1.8%). About 25 (24.3%) out of 103 E. coli and K. pneumoniae isolates were ESBLs positive by DDST, and
22 (88.0%) out of them had ESBLs encoding genes by conventional PCR. The most common gene detected was blaTEM
(59.1%), followed by blaSHV (27.3%). CTX-M had not been detected in any of testes isolates.
Conclusion: blaTEM and blaSHV genes were detected in 22 out of 25 ESBLs producing E. coli and K. pneumoniae isolates
phenotypically detected by DDST. blaTEM was found to be the predominant gene (59.1%), while blaCTX-Mene was not
detected in any of tested isolates.
Extended Spectrum β-Lactamases; Type 2 diabetes mellitus; Urinary tract infections; Phenotypic and genotypic methods.