Dataset Information

Molecular epidemiological and phylogenetic associations of two novel putative virulence genes, iha and iroN(E. coli), among Escherichia coli isolates from patients with urosepsis.

ABSTRACT: Two novel putative Escherichia coli virulence genes, iha and iroN from E. coli (iroN(E. coli)), were detected in 55 and 39%, respectively, of 67 E. coli isolates from patients with urosepsis. iha and iroN(E. coli) exhibited divergent associations with other putative virulence genes, phylogenetic markers, host characteristics, and antimicrobial resistance.

SUBMITTER: Johnson JR

PROVIDER: S-EPMC97527 | biostudies-literature | 2000 May

REPOSITORIES: biostudies-literature

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Molecular epidemiological and phylogenetic associations of two novel putative virulence genes, iha and iroN(E. coli), among Escherichia coli isolates from patients with urosepsis.

Johnson J R JR Russo T A TA Tarr P I PI Carlino U U Bilge S S SS Vary J C JC Stell A L AL

Infection and immunity 20000501 5

Two novel putative Escherichia coli virulence genes, iha and iroN from E. coli (iroN(E. coli)), were detected in 55 and 39%, respectively, of 67 E. coli isolates from patients with urosepsis. iha and iroN(E. coli) exhibited divergent associations with other putative virulence genes, phylogenetic markers, host characteristics, and antimicrobial resistance. ...[more]

PMID: 10769012

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Project description:Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen that causes acute and chronic diarrhea among children, human immunodeficiency virus-infected patients, and travelers to developing regions of the world. The pathogenesis of EAEC strains involves the production of biofilm. In this study, we determined the association between presence of putative EAEC virulence genes and biofilm formation in 57 EAEC isolates (as defined by HEp-2 adherence) from travelers with diarrhea and in 18 EAEC isolates from travelers without diarrhea. Twelve nondiarrheagenic E. coli isolates from healthy travelers were used as controls. Biofilm formation was measured by using a microtiter plate assay with the crystal violet staining method, and the presence of the putative EAEC virulence genes aap, aatA, aggR, astA, irp2, pet, set1A, and shf was determined by PCR. EAEC isolates were more likely to produce biofilm than nondiarrheagenic E. coli isolates (P = 0.027), and the production of biofilm was associated with the virulence genes aggR, set1A, aatA, and irp2, which were found in 16 (40%), 17 (43%), 10 (25%), and 27 (68%) of the biofilm producers versus only 4 (11%), 6 (6%), 2 (6%), and 15 (43%) in non-biofilm producers (P = 0.008 for aggR, P = 0.0004 for set1A, P = 0.029 for aatA, and P = 0.04 for irp2). Although the proportion of EAEC isolates producing biofilm in patients with diarrhea (51%) was similar to that in patients without diarrhea (61%), biofilm production was related to the carriage of aggR (P = 0.015), set1A (P = 0.001), and aatA (P = 0.025). Since aggR is a master regulator of EAEC, the presence of aap (P = 0.004), astA (P = 0.001), irp2 (P = 0.0006), pet (P = 0.002), and set1A (P = 0.014) in an aggR versus an aggR-lacking background was investigated and was also found to be associated with biofilm production. This study suggests that biofilm formation is a common phenomenon among EAEC isolates derived from travelers with or without diarrhea and that multiple genes associated with biofilm formation are regulated by aggR.

Project description:BackgroundAntibiotic resistance is an increasing phenomenon in many bacterial pathogens including uropathogenic Escherichia coli. Hypothetical anti-virulent agents could be a solution, but first clear virulence associated gene-pool of antibiotic resistant isolates have to be determined. The aim of this study is to investigate the significant associations between genes encoding VFs with antibiotic resistance and phylogenetic groups in UPEC isolates.ResultsThe majority of 248 UPEC isolates belonged to phylogenetic group B2 (67.3%). The maximum and minimum resistance was attributed to amoxicillin (90.3%) and both fosfomycin and imipenem (1.6%) respectively. 11.3% of isolates were resistant to all antibiotic agents except that of imipenem, nitrofurantoin and fosfomycin. These highly resistant isolates were placed only in group B2 and D. The most prevalent virulence gene was ompA (93.5%). The hlyA was the only virulence gene that was significantly more prevalent in the highly resistant isolates. The ompA, malX and hlyA genes were obviously more abundant in the antibiotic resistant isolates in comparison to susceptible isolates. The papC gene was associated with amoxicillin resistance (p-value = 0.006, odds ratio: 26.00).ConclusionsIncreased resistance to first line drugs prescribed for UTIs were detected in CA-UPEC isolates in our study.. Minimal resistance was observed against nitrofurantoin, fosfomycin and imipenem. Therefore, they are introduced for application in empirical therapy of UTIs. Fosfomycin may be the most effective antibiotic agent against highly resistant UPEC isolates. The presence of the ompA, malX and hlyA genes were significantly associated with resistance to different antibiotic agents. We assume that the ability of UPEC isolates to upgrade their antibiotic resistance capacity may occurs in compliance with the preliminary existence of specific virulence associated genes. But, more investigation with higher number of bacterial isolates, further virulence associated genes and comparison of gene pools from CA-UPEC isolates with HA-UPEC are proposed to confirm these finding and discovering new aspects of this association.

Project description:Escherichia coli often carries linked antimicrobial resistance genes on transmissible genetic elements. Through coselection, antimicrobial use may select for unrelated but linked resistance or virulence genes. This study used unconditional statistical associations to investigate the relationships between antimicrobial resistance phenotypes and antimicrobial resistance genes in 151 E. coli isolates from healthy pigs. Phenotypic resistance to each drug was significantly associated with phenotypic resistance to at least one other drug, and every association found that the probability of observing the outcome resistance was increased by the presence of the predictor resistance. With one exception, each statistical association that was identified between a pair of resistance genes had a corresponding significant association identified between the phenotypes mediated by those genes. This suggests that associations between resistance phenotypes might predict coselection. If this hypothesis is confirmed, evaluation of the associations between resistance phenotypes could improve our knowledge of coselection dynamics and provide a cost-effective way to evaluate existing data until large-scale genotypic data collection becomes feasible. This could enable policy makers and users of antimicrobials to consider coselection in antimicrobial use decisions. This study also considered the unconditional relationships between resistance and virulence genes in E. coli from healthy pigs (aidA-1, eae, elt, estA, estB, fedA1, stx1, and stx2). Positive statistical associations would suggest that antimicrobial use may select for virulence in bacteria that may contaminate food or cause diarrhea in pigs. Fortunately, the odds of detecting a virulence gene were rarely increased by the presence of an antimicrobial resistance gene. This suggests that on-farm antimicrobial use did not select for the examined virulence factors in E. coli carried by this population of healthy pigs.

Dataset Information

Molecular epidemiological and phylogenetic associations of two novel putative virulence genes, iha and iroN(E. coli), among Escherichia coli isolates from patients with urosepsis.

Publications

Molecular epidemiological and phylogenetic associations of two novel putative virulence genes, iha and iroN(E. coli), among Escherichia coli isolates from patients with urosepsis.

Similar Datasets

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