Background The context and purpose of the study: The spready dissemination of resistance mechanisms among extended spectrum beta-lactamases (ESBL) producing bacterial isolates has increasingly been reported. There is an urgent need to explore the antibacterial property of nontoxic biosafe compounds. This In-vitro experimental study aimed to evaluate the effect of silver nanoparticles (AgNPs) alone and in combination with ineffective antibiotics against ESBL producing isolates. Results Ciprofloxacin with AgNPs combination had the highest synergistic percentage against 91.43% of ESBL Escherichia coli isolates, and it was additive against 8.57% of them. As regards ESBL K. pneumoniae isolates, AgNPs with cefotaxime were synergistic against 75.00% of them, followed by ceftazidime and ciprofloxacin (62.50%). The least effective combination was ampicillin with AgNPs. The greatest enhancement of activity of the antibiotics was observed at silver minimum inhibitory concentration (MICAg) MICAg/2 and MICAg/4. At lower AgNPs concentrations, enhanced effects were less obvious. AgNPs inhibited the production of beta-lactamase enzymes in 91.43% of E. coli and 75% of Klebsiella pneumoniae isolates. Conclusion AgNPs are a valuable alternative to combat drug resistance, as they had synergistic effects when combined with different ineffective antibiotics against ESBL producing bacteria. AgNPs had lowered MIC values of antibiotics by several folds. Moreover, they inhibited the production of beta-lactamase enzymes.

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 signifi- cant 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 Pseu- domonas 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. Keywords: Extended Spectrum β-Lactamases; Type 2 diabetes mellitus; Urinary tract infections; Phenotypic; genotypic methods.