Phenotypic and Molecular Characterization of Extended-Spectrum β-Lactamase Produced by Escherichia coli, and Klebsiella pneumoniae Isolates in an Educational Hospital

Abstract

Background:Extended-spectrum beta-lactamases (ESBLs) are a group of enzymes that hydrolyze antibiotics, including those containing new cephalosporins, and they are found in a significant percentage of Escherichia coli and Klebsiella pneumoniae strains. With the widespread use of antibiotics, difficulties with infection therapy caused by drug resistant organisms, especially those that have acquired resistance to beta-lactams, such as broad-spectrum cephalosporins, have amplified the above-mentioned organisms.Objectives:This study was conducted to characterize ESBLs among E. coli and K. pneumonia isolates by molecular and phenotypic methods.Materials and Methods:Different strains of E. coli and K. pneumonia were collected from patients with urinary tract infections. The ESBL phenotype was determined by a double disk diffusion test (DDDT). In addition, polymerase chain reaction (PCR) analysis specific for β-lactamase genes of the TEM and SHV family was carried out. The PCR products were run on agarose and examined for DNA bands.Results:A total of 245 E. coli and 55 K. pneumonia strains were isolated from different samples. In total, 128 of the 300 isolates were confirmed as potential ESBLs producers as follows: 107 (43.67%) E. coli and 21 (38.18%) K. pneumonia. ESBLs genes were found in 24 isolates (18.75%): 21 E. coli and 3 K. pneumonia isolates. The TEM gene was present in 13 (12.14%) E. coli strains, but it was not detected in K. pneumonia. In addition, the SHV gene was present in 8 (7.47%) E. coli and 3 (14.28%) K. pneumonia isolates. Five (4.67%) of the E. coli isolates harbored both TEM and SHV genes. All isolates (100%) were susceptible to imipenem. The lowest rates of resistance to other antibiotics were observed for; piperacillin-tazobactam (6.25%), amikacin (12.5%) and gentamicin (14.84%). The rates of resistance to other antibiotics were as follow: nitrofurantoin (16.4%), nalidixic acid (23.43), co-trimoxazole (25%), cefepime (32%), ciprofloxacin (55.46%), ampicillin (69.53%), ceftazidime (100%), and cefotaxime (100%).Conclusions:The results of this study indicate the widespread prevalence of ESBLs and multiple antibiotic resistance in E. coli and K. pneumoniae. Therefore, beta-lactam antibiotics and beta-lactamase inhibitors or carbapenems should be prescribed based on an antibacterial susceptibility test.

Frequency Assessment of OXA-10 and PER β-Lactamase Genes and Determination of Minimum Inhibitory Concentration in Klebsiella Strains Isolated from Urinary Tract Infections

“…In a study conducted by Gholipour et al in Isfahan, the results of the antibiotic resistance pattern for nalidixic acid, gentamicin, cefepime, and amikacin were lower than those reported in this study, which is consistent with our study for the low resistance to amikacin (24). The confirmed phenotypic test results in this study indicated that 66.6% and 17.7% of the isolates were able to produce ESBL among inpatients and outpatients.…”

The Urinary System Infections caused by Extended-Spectrum-β-Lactamase-producing Escherichia coli and Klebsiella pneumoniae Strains

“…Carbapenems are potent antibiotics which possess the broadest spectrum of activity. Carbapenems, such as imipenem and meropenem, are commonly used for the treatment of ESBL-positive and Gram-negative bacterial infections (1,3,18). Resistance rates of carbapenems have been reported between 0-11.1% (1,18).…”

“…ESBL-producing strains have been reported by numerous studies in different parts of the world. In multicenter studies, the rates of ESBL-producing bacteria vary between 1-74% depending on the countries and regions (3,10,11). In Turkey, however, the rates of ESBL-positive E. coli and K. pneumoniae strains have been reported between 21-29% and 35-49%, respectively (5,(12)(13)(14).…”

“…In many USI, the treatment fails due to increased bacterial resistance against antibiotics. Moreover, this resistance may also be increased by the antibiotics used in the treatment (2,3). Production of β-Lactamase enzymes is an important mechanism of resistance in Gramnegative bacteria.…”

Molecular Characterisation of ESBL producer E. coli

“…Thus present study data indicated that OXA gene demonstrated in 100% of ESBL E. coli uropathogenic isolates tested in this study, while TEM gene presented in 66.7% of the isolates and 60% were harbouring SHV gene. Previous studies reported variable gene frequencies, 76% for OXA in Ireland [31], while TEM gene reported in 86.24% of E. coli ESBL isolates in Turkey [28], 40% in Japan [29], 34% in Ireland [31], 16.81% in Iran [36], 10% in Iraq [33], 5% in Kenya [37], and 0.9% in Japan [15]. But TEM genotype was found in 80% of E. coli ESBL isolates in Japan [29], 72.23% in Turkey [28], 12.1% in Iran [36], 3.33% south Korea [32], 3% in Ireland [31], 3% in Kenya [37] and 2.8% in Japan [15].…”