Abstract
The present work set out to search for a virulence repertoire distinctive for Escherichia coli causing primitive acute pyelonephritis (APN). To this end, the virulence potential of 18 E. coli APN strains was genotypically and phenotypically assessed, comparatively with 19 strains causing recurrent cystitis (RC), and 16 clinically not significant (control, CO) strains. Most of the strains belong to phylogenetic group B1 (69.8%; p<0.01), and APN strains showed unique features, which are the presence of phylogroup A, and the absence of phylogroup B2 and non-typeable strains. Overall, the most dominant virulence factor genes (VFGs) were ecpA and fyuA (92.4 and 86.7%, respectively; p<0.05), and the mean number of VFGs was significantly higher in uropathogenic strains. Particularly, papAH and malX were exclusive for uropathogenic strains. APN and RC strains showed a significantly higher prevalence of fyuA, usp, and malX than of CO strains. Compared to RC strains, APN ones showed a higher prevalence of iha, but a lower prevalence of iroN, cnf1, and kpsMT-II. Hierarchical cluster analysis showed a higher proportion of two gene clusters (malX and usp, and fyuA and ecpA) were detected in the APN and RC groups than in CO, whereas iutA and iha clusters were detected more frequently in APN strains. The motility level did not differ among the study-groups and phylogroups considered, although a higher proportion of swarming strains was observed in APN strains. Antibiotic-resistance rates were generally low except for ampicillin (37.7%), and were not associated with specific study- or phylogenetic groups. APN and RC strains produced more biofilm than CO strains. In APN strains, iha was associated with higher biofilm biomass formation, whereas iroN and KpSMT-K1 were associated with a lower amount of biofilm biomass. Further work is needed to grasp the virulence and fitness mechanisms adopted by E. coli causing APN, and hence develop new therapeutic and prophylactic approaches.
Highlights
Acute pyelonephritis (APN) is a very common community infection in women [1]
We examined the distribution of both genotypic (VFGs, phylogenetic groups), and phenotypic traits among E. coli isolates from women with primitive acute pyelonephritis (APN), as compared to those isolated from women with recurrent cystitis (RC) and healthy controls
We found no differences in virulence factor genes (VFGs) score among phylogroups within each study-group, only B1 strains showed the following virulence traits: namely, that iha is significantly associated with APN, kpsMT-II and malX are associated with RC, whereas fyuA is significantly more prevalent in clinical (APN and RC) than control strains
Summary
Acute pyelonephritis (APN) is a very common community infection in women [1]. the associated mortality is only 0.7%, APN sometimes progresses to sepsis, uremia and multiorgan failure and, there can be dismal outcomes [2].Pyelonephritis is usually caused by ascent of bacteria from the bladder. Acute pyelonephritis (APN) is a very common community infection in women [1]. The most common pathogens in APN belong to the Enterobacteriaceae family, with Escherichia coli representing the leading cause in more than 80% of cases [3, 4]. Other microorganisms contributing to the pathogenesis of APN include Citrobacter spp, Proteus spp, Klebsiella spp, and enterococci [3, 4]. Uropathogenic E. coli (UPEC) expresses a variety of virulence factors that contribute to its capacity to colonize the urinary tract and cause disease. Several studies have shown that virulence factors do not act individually but in a coordinated way to guarantee the successful survival and persistence of UPEC in the hostile environment of the urinary tract [6,7,8]
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