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ObjectivesUropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections (UTIs). Here, we determined whether sensitivity to antibiotics was related to the prevalence of iron scavenging genes, or to biofilm and hemolysis formation.MethodsA total of 110 UPEC and 30 E coli isolates were collected from the urine of UTI patients and feces of healthy individuals without UTI, respectively. The presence of iron receptor genes and phenotypic properties were evaluated by polymerase chain reaction and phenotypic methods, respectively. Susceptibility to routine antibiotics was evaluated using the disc diffusion method.ResultsThe prevalence of iron scavenging genes ranged from 21.8% (ireA) to 84.5% (chuA) in the UPEC. Resistance to ceftazidime and cefotaxime was significantly correlated with the presence of fyuA and iutA iron genes. Biofilm production was significantly associated with the prevalence of fyuA and hma iron genes. A higher degree of antibiotic resistance was exhibited by isolates that produced biofilms than by their non-biofilm producing counterparts.ConclusionOur study clearly indicates that biofilm production is associated with antibiotic resistance, and that iron receptors and hemolysin production also contribute to reduced antibiotic sensitivity. These results further our understanding of the role that these virulence factors play during UPEC pathogenesis, which in turn may be valuable for the development of novel treatment strategies against UTIs.

Purpose: Proteus mirabilis is one of the most important agents of urinary tract infection (UTI). As there are limited data abou the pathogenicity P. mirabilis isolated from Iran, we investigated the virulence characteristics and antibiotic resistance in the isolates. Finally, the genotypic patterns were evaluated by Pulse field gel electrophoresis (PFGE). Methods: A total of 110 isolates of P. mirabilis causing UTIs were isolated from patients in Tehran, Iran. The virulence characteristics and antimicrobial susceptibility were assayed using phenotypic methods. Extended-spectrum β-lactamases (ESBLs) production was assayed by the combination disk diffusion test (CDDT). Presence of virulence genes and antimicrobial-resistant genes was detected by Polymerase chain reaction (PCR). Finally, thirty-three isolates were selected for PFGE. Results: All isolates showed the ability of biofilm and hemolysin formation. Antibiotic resistance ranged from 59.1% about cotrimoxazole to 2.7% about amoxicillin-clavulanic acid. Sixteen (14.5%) of the isolates were classified as multi-drug resistant (MDR). All isolates amplified mrpH, mrpA, pmfA, ureG and hpmA genes. Furthermore, the prevalence of zapA, fliC, ptaA, and ucaA genes was 98.2%, 98.2%, 95.5%, and 95.5%, respectively. The prevalence of plasmidmediated quinolone resistance (PMQR) genes was 4.5% and 0.9% for aac(6ʹ)-Ib-cr and qnrA, respectively. Twenty-eight pulsotypes were detected among the 33 isolates by PFGE that pulsotypes 1, 2 and 4 with two isolates and pulsotype 3 with three isolates were the most prevalent ones. Conclusion: It was found that the P. mirabilis isolates had high frequency of virulence factors. In addition, antibiotic resistance to some antibiotics and also production of ESBLs is alarming and shows the need for hygienic procedures to prevent the dissemination of antibiotic resistance. Although PFGE showed genetic diversity among the isolates, finding of several pulsotypes among the isolates should be considered an alarm to prevent these infections in hospital environments.

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Culture supernates of 16 strains of EPEC belonging to 6 different serogroups, when assayed on Chinese Hamster Ovary (CHO) cells up to 96–120 h, induced distinct morphological changes. The supernate activities were heat‐labile, unrelated to heat‐labile enterotoxin (LT), verotoxin (VT), or hemolysin, did not show necrosis in rabbit skin and caused no fluid secretion in the rabbit ileal loop assay (RILA). Simulatneous production of CLDT and heat‐stable enterotoxin (ST) were detected in four EPEC strains.

Summary. Three hundred and nine strains of Escherichia coli isolated from infants and children with diarrhoea but not belonging to any recognised classes of diarrhoeagenic E. coli were investigated for their ability to adhere to HeLa cells in the presence of D-mannose. An enteroadherent-aggregative pattern (EAgg) was observed in 32-03 YO, localised adherence (LA) in 4.5 YO, diffuse adherence (DA) in 5.8 YO, and LA/DA and EAgg/LA in 1.9 YO and 1.2 YO of the isolates respectively. The results obtained with 100 control isolates were: EAgg 17 YO, LA 2 %, DA YO, LA/DA 2%, EAgg/LA 6 % and DA/EAgg 1 %. No adherence was manifested by 168 (54.36 YO) of 309 diarrhoeal isolates and 70 YO of the 100 control isolates. The results of this study showed that amongst non-enteropathogenic E. coli, strains exhibiting the EAgg pattern are significantly associated with diarrhoea (p < 0.005). Most of these strains showed a pattern of multiple drug resistance.

Uropathogenic Escherichia coli (UPEC) are common pathogens in urinary tract infections (UTIs), which show resistance to antibiotics. Therefore, there is a need for a vaccine to reduce susceptibility to the infection. In the present study, bioinformatics approaches were employed to predict the best B and T-cell epitopes of UPEC virulence proteins to develop a multiepitope vaccine candidate against UPEC. Then, the efficacy of the candidate was studied with and without Freund adjuvant. Using bioinformatics methods, 3 epitope-rich domains of IutA and FimH antigens were selected to construct the fusion. Molecular docking and Molecular dynamics (MD) simulation were employed to investigate in silico interaction between designed vaccine and Toll-like receptor 4 (TLR4). Our results showed that the levels of IgG and IgA antibodies were improved in the serum and mucosal samples of the vaccinated mice, and the IgG responses were maintained for at least 6 months. The fusion protein was also able to enhance the level of cytokines IFN.γ (Th1), IL.4 (Th2), and IL.17. In challenge experiments, all vaccine combinations showed high potency in the protection of the urinary tract even after 6 months post first injection. The present study indicates that the designed candidate is able to evoke strong protective responses which warrant further studies.

In this study, the silk fibroin nanoparticle (SFNP) was used as a nanoadjuvant in combination with a multiepitopebased vaccine for urinary tract infection (UTI). Nanoparticles containing the fusion protein were analyzed for physicochemical properties, toxicity, release profile, and in vivo potency. The synthesized nanovaccine showed a spherical shape with a mean particle size of 180 nm and an encapsulation efficiency of 88%. Antigen release from SFNPs was 18% after 42 days. The SFNPs showed a zeta potential of −29 mV and had no toxic effect on the L929 cells in vitro. SFNPs in the vaccine formulations promoted humoral and cellular (IFN-γ, IL-4, and IL-17) immune responses in comparison to controls. Immunization of mice with antigen-encapsulated SFNPs significantly increased the total IgG as well as IgG2a/IgG1 ratio. In addition, this formulation triggered concurrently type 1 (Th1) and type 2 (Th2) immune responses, with a Th1-polarized response. Furthermore, highly effective protection of the bladder and kidney against experimental UTI was obtained by using the nanoadjuvant containing the antigen for 6 months. The results demonstrated that SFNPs can be proposed as potent adjuvants or vaccine carriers to develop new and more effective nanovaccine formulations in the future.