Molecular typification of Escherichia coli from community-acquired urinary tract infections in Mexico.

One hundred and five uropathogenic Escherichia coli (UPEC) strains from patients with community-acquired urinary tract infections were characterized according to phylogenetic group, virulence factors, serogroup, antibiotic resistance, and genotype. The pathogenic phylogenetic groups (B2, D, and F) were found in 71.4% of the tested strains. Among them, the main uropathogenic serogroups were O8, O25, and O75, in which 97.1% of the strains had a multidrug-resistant profile. Sixteen virulence genes were analysed using a combination of polymerase chain reaction (PCR) assays, with the fimH, irp-2, iutA, aer, iucC, PAI, sat, iroN, usp, and cnf1 genes being mainly found in pathogenic phylogroups. The E. coli O25b-ST131 clone was identified in 32% of the strains assigned to the pathogenic phylogroup B2. These findings demonstrate that virulence genes encoding adhesin components, iron-acquisition systems, toxins, and pathogenicity-associated islands were highly prevalent among the pathogenic phylogroup of UPEC strains.

Identification and characterization of class 1 integrons among multidrug-resistant uropathogenic Escherichia coli strains in Mexico.

This study aimed to identify and characterize integrons among multidrug-resistant (MDR) uropathogenic Escherichia coli (UPEC) from outpatients in Mexico City, Mexico. PCR assays were used to screen for the presence of class 1, 2 and 3 integrons, whose PCR products were sequenced to identify the inserted gene cassettes within the variable regions. Out of 83 tested strains, 53 (63.9%) were positive for the presence of class 1 integrons, whereas no integrons were detected in the remaining strains, regardless of their classes. Most of the strains carrying the intI1 gene belonged to the extraintestinal B2 (41.5%) and commensal A (32.1%) phylogroups, and to a lesser extent, the extraintestinal D (20.8%) and commensal B1 (5.7%) phylogroups. Moreover, 8 different gene cassette arrangements were detected, with dfrA17 and aadA5 being the most common (32.1% of the class 1 integron-positive strains), which confer resistance to trimethoprim/sulfamethoxazole and aminoglycosides, respectively. Our results suggest that class 1 integrons are widely distributed among MDR-UPEC strains in Mexico, which may directly or indirectly contribute to the selection of MDR strains. These findings are important for a better understanding of the factors and mechanisms that promote multidrug resistance among UPEC strains.

|Isolation and characterization of novel bacteriophages as a potential therapeutic option for Escherichia coli urinary tract infections.

Urinary tract infections (UTIs) are mainly caused by uropathogenic Escherichia coli (UPEC), whose impact can be exacerbated by multidrug-resistant (MDR) strains. Effective control strategies are, therefore, urgently needed. Among them, phage therapy represents a suitable alternative. Here, we describe the isolation and characterization of novel phages from wastewater samples, as well as their lytic activity against biofilm and adherence of UPEC to HEp-2 cells. The results demonstrated that phage vB_EcoM-phiEc1 (ϕEc1) belongs to Myoviridae family, whereas vB_EcoS-phiEc3 (ϕEc3) and vB_EcoS-phiEc4 (ϕEc4) belong to Siphoviridae family. Phages showed lytic activity against UPEC and gut commensal strains. Phage ϕEc1 lysed UPEC serogroups, whereas phages ϕEc3 and ϕEc4 lysed only UTI strains with higher prevalence toward the O25 serogroup. Moreover, phages ϕEc1 and ϕEc3 decreased both biofilm formation and adherence, whereas ϕEc4 was able to decrease adherence but not biofilm formation. In conclusion, these novel phages showed the ability to decrease biofilm and bacterial adherence, making them promising candidates for effective adjuvant treatment against UTIs caused by MDR UPEC strains. KEY POINTS: Phage with lytic activity against MDR UPEC strains were isolated and characterized under in vitro conditions. A novel method was proposed to evaluate phage activity against bacterial adherence in HEp-2 cell.. Phages represent a suitable strategy to control infections caused by MDR bacteria.

Characterization of a novel AraC/XylS-regulated family of N-acyltransferases in pathogens of the order Enterobacterales.

Enteroaggregative Escherichia coli (EAEC) is a diarrheagenic pathotype associated with traveler's diarrhea, foodborne outbreaks and sporadic diarrhea in industrialized and developing countries. Regulation of virulence in EAEC is mediated by AggR and its negative regulator Aar. Together, they control the expression of at least 210 genes. On the other hand, we observed that about one third of Aar-regulated genes are related to metabolism and transport. In this study we show the AggR/Aar duo controls the metabolism of lipids. Accordingly, we show that AatD, encoded in the AggR-regulated aat operon (aatPABCD) is an N-acyltransferase structurally similar to the essential Apolipoprotein N-acyltransferase Lnt and is required for the acylation of Aap (anti-aggregation protein). Deletion of aatD impairs post-translational modification of Aap and causes its accumulation in the bacterial periplasm. trans-complementation of 042aatD mutant with the AatD homolog of ETEC or with the N-acyltransferase Lnt reestablished translocation of Aap. Site-directed mutagenesis of the E207 residue in the putative acyltransferase catalytic triad disrupted the activity of AatD and caused accumulation of Aap in the periplasm due to reduced translocation of Aap at the bacterial surface. Furthermore, Mass spectroscopy revealed that Aap is acylated in a putative lipobox at the N-terminal of the mature protein, implying that Aap is a lipoprotein. Lastly, deletion of aatD impairs bacterial colonization of the streptomycin-treated mouse model. Our findings unveiled a novel N-acyltransferase family associated with bacterial virulence, and that is tightly regulated by AraC/XylS regulators in the order Enterobacterales.

Characterization of auto-agglutinating and non-typeable uropathogenic Escherichia coli strains.

INTRODUCTION: Uropathogenic Escherichia coli (UPEC) are the main etiological agent of urinary tract infections (UTIs). Association between different serotypes and UTIs is known, however, some strains are incapable to be serotyped. The aim of this work was to study bthe phenotypical and genotypical characteristics of 113 non-typeable (NT) and auto-agglutinating (AA) E. coli strains, isolated from UTIs in children and adults. METHODOLOGY: The 113 UPEC strains were analyzed by PCR assays using specific primers to determine their serogroups, fimH, papC, iutA, sat, hlyCA and cnf1, virulence associated genes, and chuA, yjaA and TSPE4.C2 for phylogroup determination. Additionally, the diffusion disk method was performed to evaluate the antimicrobial resistance to 18 antimicrobial agents. RESULTS: Using the PCR assay, 63% (71) of the strains were genotyped showing O25 and O75 as the most common serogroups. The virulence genes fimH (86%) and iutA (74%) were the most prevalent, in relation to the phylogroups the commensal (A and B1) and virulent (B2 and D) showed similar frequencies (P > 0.05). The antimicrobial susceptibility test showed a high percentage (73%) of multidrug-resistant strains. CONCLUSIONS: The genotyping allowed identifying the serogroup in many of the strains that could not be typed by traditional serology. The strains carried virulence genes and were multidrug-resistant in both, commensal and virulent phylogroups. Our findings revealed that, in addition to the classical UPEC serogroups, there are pathogenic serogroups not reported yet.

Characterization of Escherichia coli causing community acquired urinary tract infections in Mexico City.

The O25-ST131 clone was identified within 169 uropathogenic Escherichia coli (UPEC) strains. The 44.8% of the 29 O25-ST131 clones detected were positive to least to one extended-spectrum ß-lactamase gene. The phylogroup D was mainly found. The O25-ST131 clone appeared to be associated with community-acquired UTI in Mexico City.