Are Quinolone‐Resistant UropathogenicEscherichia coliLess Virulent?

Abstract

The prevalence of hemolysin, type 1 fimbriae, P fimbriae, cytotoxic necrotizing factor-1 (CNF-1), aerobactin, and autotransporter toxin (sat) was analyzed by polymerase chain reaction and phenotypic assays of 42 epidemiologically unrelated Escherichia coli strains causing acute pyelonephritis in women (21 nalidixic acid-susceptible and 21 nalidixic acid-resistant strains) and 58 E. coli strains causing cystitis in women (29 nalidixic acid-susceptible and 29 nalidixic acid-resistant strains). Hemolysin and CNF-1 were less prevalent (P<.05) in nalidixic acid-resistant than in nalidixic acid-susceptible E. coli strains from patients with either pyelonephritis (14.3% vs. 52.4%) or cystitis (0% vs. 31.0%). Among E. coli strains causing cystitis, type 1 fimbriae expression was less prevalent (P<.05) in the nalidixic acid-resistant group (55.2%) than in the nalidixic acid-susceptible group (86.2%). None of the nalidixic acid-resistant and 20.7% of the nalidixic acid-susceptible strains causing cystitis showed the proteolytic toxin Sat (P<.05). These results suggest that resistance to quinolones may be associated with a decrease in the presence or the expression of some virulence factors in uropathogenic E. coli.

The Role of Host Factors and Bacterial Virulence Genes in the Development of Pyelonephritis Caused by Escherichia coli in Renal Transplant Recipients

“…Although some investigators suggested that virulence genes increased antibiotic resistance of previously resistant strains (16), others observed that quinoloneresistant E. coli strains were more prone to induce Cys rather than PN (17,18,20) because of decreased renal invasive capacity concomitantly acquired by the mutation. Our findings, in agreement with those reports, showed a lower proportion of E. coli resistance to first-generation quinolones in PN isolates: the risk of resistance in PN isolates to nalidixic acid was reduced in the whole sample (OR ϭ 2.90) and to pipemidic acid in the Tx group (OR ϭ 2.57).…”

“…On the other hand, other investigators have suggested that quinolone resistance involves a genotypic change associated with the loss of virulence factors in E. coli (17)(18)(19)(20).…”

Antibiotic Resistance in Extra Intestinal Pathogenic Escherichia Coli

“…Vila suggested that a possible reason for this is that virulence genes could be lost concomitant with a mutation at codon 83 of the gyrA gene, which affects super coiling of DNA, leading to changes in gene expression. Another reason is that with exposure to quinolones and development of resistance to these agents, there is a concomitant increase in the deletion and transposition of pathogenicity islands (PAIs) [7]. Soto et al [6] found that uropathogenic E. coli strains incubated with sub inhibitory concentrations of ciprofloxacin showed partial or total loss of virulence genes encoded within PAIs [6].…”

Antibiotic resistance and virulence genes of extraintestinal pathogenic Escherichia coli from tropical estuary, south India

“…More recent data demonstrate a similar negative association between antibiotic resistance and virulence factors or a B2 phylogenetic background [33,34,42]. This has been interpreted as loss of virulence factors concomitant with mutation to resistance [43]. However, this hypothesis does not account for the phylogenetic shifts (away from group B2) observed among resistant isolates, which suggest that resistant isolates derive primarily from distinct, less virulent bacterial populations [44,45].…”