BackgroundResistance to cephalosporins in Enterobacteriaceae is mainly due to the production of extended-spectrum beta-lactamase (ESBL). Little is known about ESBL-producing bacteria in Bangladesh. Therefore, the study presents results of phenotypic and molecular characterization of ESBL-producing Escherichia coli from hospitals in Bangladesh.MethodsA total of 339 E. coli isolated from patients with urinary tract and wound infections attending three different medical hospitals in urban and rural areas of Bangladesh between 2003–2007 were screened for ESBL-production by the double disk diffusion test. Isolates with ESBL-phenotype were further characterized by antibiotic susceptibility testing, PCR and sequencing of different β-lactamase and virulence genes, serotyping, and XbaI-macrorestriction followed by pulsed-field gel electrophoresis (PFGE).ResultsWe identified 40 E. coli with ESBL phenotype. These isolates were resistant to ceftriaxone, ceftazidime, cefotaxime, aztreonam, cefepime, and nalidixic acid but remained susceptible to imipenem. All but one isolate were additionally resistant to ciprofloxacin, and 3 isolates were resistant to cefoxitin. ESBL genes of blaCTX-M-1-group were detected in all isolates; blaTEM-type and blaOXA-1-type genes were detected in 33 (82.5%) and 19 (47.5%) isolates, respectively. Virulence genes that are present in diarrhoeagenic E. coli were not found. Class-1 integron was present in 20 (50%) isolates. All the ESBL-producing E. coli isolates harbored plasmids ranging between 1.1 and 120 MDa. PFGE-typing revealed 26 different pulsotypes, but identical pulsotype showed 6 isolates of serotype O25:H4.ConclusionThe prevalence of multidrug-resistant ESBL-producing E. coli isolates appears to be high and the majority of the isolates were positive for bla CTX-M. Although there was genetic heterogeneity among isolates, presence of a cluster of isolates belonging to serotype O25:H4 indicates dissemination of the pandemic uropathogenic E. coli clone in Bangladesh.

Urinary tract infection (UTI) is a very common disease among women. It has been estimated that about 50 to 60.0% of women will get at least one urinary tract infection in their lifetime 1 . In uncomplicated UTI the infection is not associated with structural or functional disorders of the urinary tract. After this uncomplicated UTI around 25% of women experience a recurrent infection within 6 to 12 months, and around 5.0% have several episodes within a year 2 . Recurrent UTIs are mostly occurred in young women; however, postmenopausal women are also often affected 3 . It has been found that about 75 to 85% of uncomplicated UTIs are caused by Escherichia coli 4 . According to the classic understanding of pathogenesis, almost all recurrent UTIs are ascending re-infections by the same clone or a different clone from the rectal reservoir 5 . However, an alternative pathway has emerged. In murine cystitis, uropathogenic E coli binds to, invades, and replicate within the bladder urothelium to form intracellular bacterial communities, which dissociate and ultimately establish intracellular reservoirs that can seed recurrent UTIs 6 . The presence of exfoliated intracellular bacterial communities and filamentous bacteria in the urine of women with acute cystitis suggests that the same intracellular bacterial community pathogenic pathway could have a role in human beings. These findings support the occurrence of an intracellular bacterial niche in some women with cystitis that could have important implications for recurrence and treatment of UTIs 7 . According to international guidelines, prevention of recurrent UTIs includes counselling and behavioural modifications followed by non-antimicrobial measures; antimicrobial prophylaxis is indicated only when nonantimicrobial measures are ineffective 5 .For the prevention of UTI many non-antimicrobial measures have been tested like local hormonal support in postmenopausal women, cranberry products, probiotics, immunoactive prophylaxis, dmannose, endovesical instillation of hyaluronic acid and chondroitin sulphate 8. Evidence for most of these interventions is low or supported only by results from small prospective randomised clinical trials. Immunoprophylaxis with UroVaxom is the only intervention that has grade B recommendation because it was more efficacious than placebo in several randomised placebo-controlled trials 8 . Although UroVaxom is made from an extract of heat-killed uropathogenic E. coli and thus can stimulate an improved immune response at infected sites, such as the urinary tract, it cannot be considered a vaccine against infections exclusively caused by uropathogenic E coli. Development of a specific vaccine against extra-intestinal pathogenic E coli, including uropathogenic E coli, would offer another non-antimicrobial option for prevention of recurrent UTIs, which could provide a great clinical advantage.Huttner et al 9 have tested a bioconjugate vaccine containing the O-antigens of four E coli serotypes. This tetravalent vaccine candidate was well tolerated...

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The prevalence of extended-spectrum β-lactamases (ESBL) producing E. coli in the town of Sylhet was assessed over 12 months period. One hundred patients who had symptomatic urinary tract infections were selected for this study and urine samples were collected from the private laboratories of the community. These isolates were further confirmed as ESBL-producing E. coli by phenotypic methods were identified and selected. Patients having urinary tract infection showed 72% were female and the rest 28% were male. The investigations were carried out on female population only. The patient's age ranged from 4 years to 60 years. The highest age incidence of UTI patient was 21-30 years (28%) followed by 31-40 years (20%). Patients in the age range 41-50 years showed15% and patients above 50 years 19%. The antibiotic susceptibility test for non-ESBL showed 100% sensitivity to imipenem and meropenem. There was multidrug resistance to amoxicillin-clavulanic acid 30% ceftazidime 40%, ceftriaxone 35%, and ciprofloxacin 60%. The ESBL group were also 100% sensitive to carbapenems and the rest of resistance by percentage were amoxicillin-clavulanic acid -80%, ceftazidime-55%, ceftriaxone-80 %, ciprofloxacin 80%. The ESBL and non ESBL producing strains were separated for plasmid profile analysis. The plasmid profile showed 60% of isolates exhibit high molecular weight plasmids (>140MDa) in ESBL groups and similar results were seen in Non ESBL groups (64%). These findings suggests that both ESBL and non ESBL producing isolates harbour large size plasmids, despite the fact that ESBL-producing strains cause wide range of multi-drug resistance in the community.