Fluoroquinolone resistance in Escherichia coli isolates after exposure to non-fluoroquinolone antibiotics: a retrospective case-control study

Nitrofurantoin resistance as an indicator for multidrug resistance: an assessment of Escherichia coli urinary tract specimens in England, 2015-19

Objectives

To determine whether MDR occurs more frequently in nitrofurantoin-resistant Escherichia coli urinary isolates in England, compared with nitrofurantoin-susceptible isolates.

Methods

Using routine E. coli urine isolate antibiotic susceptibility laboratory surveillance data for England, 2015-19 inclusive, the percentage of MDR or XDR phenotype was estimated for nitrofurantoin-susceptible and nitrofurantoin-resistant laboratory-reported urinary tract samples by region, patient sex and age group.

Results

Resistance to nitrofurantoin among E. coli urinary samples decreased slightly year on year from 2.9% in 2015 to 2.3% in 2019. Among E. coli UTIs tested for nitrofurantoin susceptibility and  ≥3 additional antibiotics, the percentage that were MDR was consistently 15%-20% percentage points higher for nitrofurantoin-resistant isolates compared with nitrofurantoin-susceptible isolates. Similarly, the percentage of isolates with an XDR phenotype was higher among nitrofurantoin-resistant versus -susceptible isolates (8.7% versus 1.4%, respectively, in 2019); this disparity was greater in male patients, although variation was seen by age group in both sexes. Regional variation was also noted, with the highest MDR percentage amongst nitrofurantoin-resistant E. coli urinary samples in the London region (36.7% in 2019); the lowest was in the North East (2019: 16.9%).

Conclusions

MDR and XDR phenotypes occur more frequently in nitrofurantoin-resistant E. coli urinary isolates in England, compared with nitrofurantoin-susceptible isolates. However, nitrofurantoin resistance is low (<3%) overall. This latest study provides important insights into trends in nitrofurantoin resistance and MDR, which is of particular concern for patients ≥75 years old and those who are male. It also emphasises geographical heterogeneities within England in nitrofurantoin resistance and MDR.

Comparative study of subcutaneous, intramuscular, and oral administration of bovine pathogenic Escherichia coli bacterial ghost vaccine in mice

Escherichia coli is one of the most common bacterial pathogens in cattle. Prophylactic vaccines are considered promising strategies with the potential to reduce the incidence of colibacillosis. Some studies suggested that bacterial ghosts may serve as a novel approach for preventing bacterial infections. However, the roles of administration route on vaccine immunogenicity and efficacy have not been investigated. In this study, the efficacy of vaccination via different immune routes in generating humoral and cellular immune response was compared through subcutaneous (SC), intramuscular (IM), and oral (O) administration in female BALB/c mice with bacterial ghosts prepared using wild type Escherichia coli isolates CE9, while phosphate buffer saline (PBS) and inactivated vaccines containing aluminum adjuvants (Killed) were used as control. Our results showed that the plasmid pBV220-E-aa-SNA containing E. coli was efficiently cleaved at 42°C with 94.8% positive ratio as assessed by colony counts. Transmission electron microscopy (TEM) confirmed bacteria retained intact surface structure while devoid of cytoplasmic component. We found that total IgG titers in killed, IM and SC groups showed significant increase on 7, 14, 21 and 28 days post-immunization. The IgA level of the IM group was higher than that of all other groups on the 28th day. Meanwhile, four experimental groups showed a significant difference in IgA levels compared with PBS control. In the IM group, an increase in the relative percentages of CD3+CD4+ T cells was accompanied by an increase in the relative percentages of splenic CD3+CD8+ T cells. In comparison with the inactivated vaccine, intramuscular CE9 ghosts immunization elicited higher levels of IL-1β, IL-2, IL-6 and IL-12. Subcutaneous and intramuscular immunizations were significantly associated with improved survival in comparison with oral route, traditional vaccine and the control. Pathologic assessment revealed that less severe tissue damage and inflammation were found in lung, kidney, and intestine of IM group compared with other groups. The results above demonstrate that immunization of Escherichia coli CE9 ghosts via intramuscular injection elicits a more robust antigen-specific immune response in mice to prevent the Escherichia coli infection.

Antibiotic resistance of Escherichia coli urinary tract infections at a North Carolina community hospital: Comparison of rural and urban community type

OBJECTIVE

We aimed to identify differences in urinary E. coli resistance rates based on community type of patient residence (rural and urban).

METHODS

This cross-sectional study examined antibiotic resistance of E. coli isolates from 12,604 urine specimens at a North Carolina hospital between 2016 and 2018. Using multivariable logistic regression modeling, we investigated the association between resistance and community type, adjusting for patient age, gender, season, and setting of infection onset. Analyses were performed using SAS Version 9.3 (SAS Institute, Cary, NC) at alpha = 0.05.

RESULTS

Prevalence of resistance was highest for ampicillin (42.2%), ampicillin-sulbactam (24.7%), ciprofloxacin (21.8%), trimethoprim-sulfamethoxazole (SXT) (21.6%), and levofloxacin (21.4%). Rural compared to urban community type was significantly associated with resistance of E. coli urinary isolates to ciprofloxacin (adjusted odds ratio [aOR] = 1.29, 95% confidence interval [CI] = 1.16-1.43, P < .0001), levofloxacin (aOR = 1.28, 95% CI = 1.15-1.42, P < .0001), SXT (aOR = 1.15, 95% CI = 1.04-1.27, P = .01), and nitrofurantoin (aOR = 1.57, 95% CI = 1.13-2.17, P = .01).

CONCLUSIONS

Rural community type may influence urinary E. coli resistance to fluoroquinolones, SXT, and nitrofurantoin, indicating the need for antimicrobial stewardship interventions in medically underserved populations.