Genetic Predictive Factors for Nonsusceptible Phenotypes and Multidrug Resistance in Expanded-Spectrum Cephalosporin-Resistant Uropathogenic Escherichia coli from a Multicenter Cohort: Insights into the Phenotypic and Genetic Basis of Coresistance

Antibiotic Resistance of Urinary Tract Infection Recurrences in a Large Integrated US Healthcare System

BACKGROUND

Data on antibiotic resistance of uropathogens for urinary tract infection (UTI) recurrences are lacking.

METHODS

In a retrospective cohort of adults at Kaiser Permanente Southern California with culture-confirmed index uncomplicated UTI (uUTI) between January 2016 and December 2020, we examined the number and characteristics of subsequent culture-confirmed UTIs through 2021.

RESULTS

We identified 148 994 individuals with a culture-confirmed index uUTI (88% female, 44% Hispanic; mean age, 51 years [standard deviation, 19 years]), of whom 19% developed a subsequent culture-confirmed UTI after a median 300 days (interquartile range, 126-627 days). The proportion of UTI due to Escherichia coli was highest for index uUTI (79%) and decreased to 73% for sixth UTI (UTI 6) (P for trend < .001), while the proportion due to Klebsiella spp increased from index UTI (7%) to UTI 6 (11%) (P for trend < .001). Nonsusceptibility to ≥1 and ≥3 antibiotic classes was observed in 57% and 13% of index uUTIs, respectively, and was higher for subsequent UTIs (65% and 20%, respectively, for UTI 6). Most commonly observed antibiotic nonsusceptibility patterns included penicillins alone (12%), and penicillins and trimethoprim-sulfamethoxazole plus ≥1 additional antibiotic class (9%).

CONCLUSIONS

Antibiotic nonsusceptibility is common in UTIs and increases with subsequent UTIs. Continuous monitoring of UTI recurrences and susceptibility patterns is needed to guide treatment decisions.

Harvesting and amplifying gene cassettes confers cross-resistance to critically important antibiotics

Amikacin and piperacillin/tazobactam are frequent antibiotic choices to treat bloodstream infection, which is commonly fatal and most often caused by bacteria from the family Enterobacterales. Here we show that two gene cassettes located side-by-side in and ancestral integron similar to In37 have been "harvested" by insertion sequence IS26 as a transposon that is widely disseminated among the Enterobacterales. This transposon encodes the enzymes AAC(6')-Ib-cr and OXA-1, reported, respectively, as amikacin and piperacillin/tazobactam resistance mechanisms. However, by studying bloodstream infection isolates from 769 patients from three hospitals serving a population of 1.2 million people in South West England, we show that increased enzyme production due to mutation in an IS26/In37-derived hybrid promoter or, more commonly, increased transposon copy number is required to simultaneously remove these two key therapeutic options; in many cases leaving only the last-resort antibiotic, meropenem. These findings may help improve the accuracy of predicting piperacillin/tazobactam treatment failure, allowing stratification of patients to receive meropenem or piperacillin/tazobactam, which may improve outcome and slow the emergence of meropenem resistance.

Antimicrobial resistance profiles of Escherichia coli isolated from clinical and environmental samples: findings and implications

Background

The overuse and misuse of antimicrobials has worsened the problem of antimicrobial resistance (AMR) globally. This study investigated the AMR profiles of Escherichia coli isolated from clinical and environmental samples in Lusaka, Zambia.

Methods

This was a cross-sectional study conducted from February 2023 to June 2023 using 450 samples. VITEK® 2 Compact was used to identify E. coli and perform antimicrobial susceptibility testing. Data analysis was done using WHONET 2022 and SPSS version 25.0.

Results

Of the 450 samples, 66.7% (n = 300) were clinical samples, whereas 33.3% (n = 150) were environmental samples. Overall, 47.8% (n = 215) (37.8% clinical and 10% environmental) tested positive for E. coli. Of the 215 E. coli isolates, 66.5% were MDR and 42.8% were ESBL-producers. Most isolates were resistant to ampicillin (81.4%), sulfamethoxazole/trimethoprim (70.7%), ciprofloxacin (67.9%), levofloxacin (64.6%), ceftriaxone (62.3%) and cefuroxime (62%). Intriguingly, E. coli isolates were highly susceptible to amikacin (100%), imipenem (99.5%), nitrofurantoin (89.3%), ceftolozane/tazobactam (82%) and gentamicin (72.1%).

Conclusions

This study found a high resistance of E. coli to some antibiotics that are commonly used in humans. The isolation of MDR and ESBL-producing E. coli is a public health concern and requires urgent action. Therefore, there is a need to instigate and strengthen interventional strategies including antimicrobial stewardship programmes to combat AMR in Zambia.

Early-Onset Infection Caused by Escherichia coli Sequence Type 1193 in Late Preterm and Full-Term Neonates

Using whole-genome sequencing, we characterized Escherichia coli strains causing early-onset sepsis (EOS) in 32 neonatal cases from a 2019-2021 prospective multicenter study in France and compared them to E. coli strains collected from vaginal swab specimens from women in third-trimester gestation. We observed no major differences in phylogenetic groups or virulence profiles between the 2 collections. However, sequence type (ST) analysis showed the presence of 6/32 (19%) ST1193 strains causing EOS, the same frequency as in the highly virulent clonal group ST95. Three ST1193 strains caused meningitis, and 3 harbored extended-spectrum β-lactamase. No ST1193 strains were isolated from vaginal swab specimens. Emerging ST1193 appears to be highly prevalent, virulent, and antimicrobial resistant in neonates. However, the physiopathology of EOS caused by ST1193 has not yet been elucidated. Clinicians should be aware of the possible presence of E. coli ST1193 in prenatal and neonatal contexts and provide appropriate monitoring and treatment.

Aromatic Diboronic Acids as Effective KPC/AmpC Inhibitors

Over 30 compounds, including para-, meta-, and ortho-phenylenediboronic acids, ortho-substituted phenylboronic acids, benzenetriboronic acids, di- and triboronated thiophenes, and pyridine derivatives were investigated as potential β-lactamase inhibitors. The highest activity against KPC-type carbapenemases was found for ortho-phenylenediboronic acid 3a, which at the concentration of 8/4 mg/L reduced carbapenems' MICs up to 16/8-fold, respectively. Checkerboard assays revealed strong synergy between carbapenems and 3a with the fractional inhibitory concentrations indices of 0.1-0.32. The nitrocefin hydrolysis test and the whole cell assay with E. coli DH5α transformant carrying blaKPC-3 proved KPC enzyme being its molecular target. para-Phenylenediboronic acids efficiently potentiated carbapenems against KPC-producers and ceftazidime against AmpC-producers, whereas meta-phenylenediboronic acids enhanced only ceftazidime activity against the latter ones. Finally, the statistical analysis confirmed that ortho-phenylenediboronic acids act synergistically with carbapenems significantly stronger than other groups. Since the obtained phenylenediboronic compounds are not toxic to MRC-5 human fibroblasts at the tested concentrations, they can be considered promising scaffolds for the future development of novel KPC/AmpC inhibitors. The complexation of KPC-2 with the most representative isomeric phenylenediboronic acids 1a, 2a, and 3a was modeled by quantum mechanics/molecular mechanics calculations. Compound 3a reached the most effective configuration enabling covalent binding to the catalytic Ser70 residue.