Escherichia coli O25b-ST131 is an important cause of antimicrobial-resistant infections in women with uncomplicated cystitis

Genotypic and phenotypic profiles of antibiotic-resistant bacteria isolated from hospitalised patients in Bangladesh

OBJECTIVES

Characterisation of resistance phenotype and genotype is crucial to understanding the burden and transmission of antimicrobial resistance (AMR). This study aims to determine the spectrum of AMR and associated genes encoding aminoglycoside, macrolide and β-lactam classes of antimicrobials in bacteria isolated from hospitalised patients in Bangladesh.

METHODS

430 bacterial isolates from patients with respiratory, intestinal, wound infections and typhoid fever, presenting to clinical care from 2015 to 2019, were examined. They included Escherichia coli (n = 85); Staphylococcus aureus (n = 84); Salmonella typhi (n = 82); Klebsiella pneumoniae (n = 42); Streptococcus pneumoniae (n = 36); coagulase-negative staphylococci (n = 28); Enterococcus faecalis (n = 27); Pseudomonas aeruginosa (n = 26); and Acinetobacter baumannii (n = 20). Reconfirmation of these clinical isolates and antimicrobial susceptibility tests was performed. PCR amplification using resistance gene-specific primers was done, and the amplified products were confirmed by Sanger sequencing.

RESULTS

53% of isolates were multidrug-resistant (MDR), including 97% of Escherichia coli. There was a year-wise gradual increase in MDR isolates from 2015 to 2018, and there was an almost twofold increase in the number of MDR strains isolated in 2019 (P = 0.00058). Among the 5 extended-spectrum β-lactamases investigated, CTX-M-1 was the most prevalent (63%) followed by NDM-1 (22%); Escherichia coli was the major reservoir of these genes. The ermB (55%) and aac(6')-Ib (35%) genes were the most frequently detected macrolide and aminoglycoside resistance genes, respectively.

CONCLUSION

MDR pathogens are highly prevalent in hospital settings of Bangladesh.

Association of Escherichia coli ST131 lineage with risk of urinary tract infection recurrence among young women

OBJECTIVES

The aim of this study was to test the hypothesis that urinary tract infections (UTIs) caused by Escherichia coli of the sequence type 131 (ST131) lineage are more likely to recur than UTIs caused by other E. coli lineages.

METHODS

Isolates from 221 young women with UTI caused by E. coli participating in a randomised controlled trial were used. Participants were followed for 6 months or until UTI recurrence.

RESULTS

Sequence type was not associated with risk of recurrence. Isolates in the ST131 lineage were more resistant than other STs to quinolones (6.2% vs. 1.3%) but not trimethoprim/sulfamethoxazole (15.4% vs. 15.0%).

CONCLUSIONS

These results do not support an increased risk of recurrent UTI among otherwise healthy women with UTI caused by E. coli ST131.

Emergence of extended spectrum-β-lactamase-producing Escherichia coli O25b-ST131: a major community-acquired uropathogen in infants

BACKGROUND

Escherichia coli sero-group O25b-sequence type 131 (O25b-ST131), a multidrug-resistant clonal group, is a significant pathogen in adults and children. This study investigated the genotyping and role of extended spectrum β-lactamase (ESBL)-producing E. coli O25b-ST131 and non-O25b-ST131 in urinary tract infections in infants.

METHODS

Clinical and laboratory data from 111 infants less than 1 year of age, who were hospitalized for urinary tract infections caused by ESBL-producing E. coli between 2009 and 2012 were collected. Polymerase chain reactions and multi-locus sequence typing were used to identify E. coli O25-ST131 clones. The gene blaCTX-M groups 1, 2 and 9, a specific polymerase chain reaction of CTX-M 14 and 15, were also determined in ESBL-producing E. coli isolates.

RESULTS

O25b-ST131 accounted for 65% of the 111 isolates, although 92 isolates belonged to the blaCTX-M group 9, of which most were CTX-M-14. Those with O25b-ST131 clones had similar risk factors, clinical features and outcomes as those with non-O25b-ST131. The E. coli O25b-ST131 isolates were more resistant to ciprofloxacin and gentamicin, but more susceptible to cefoxitin, minocycline and trimethoprim/sulfamethoxazole than the non-O25b-ST131 isolates. Most of the infants (78%) were previously healthy with no apparent risk factors.

CONCLUSIONS

E. coli O25b-ST131 is a major community-acquired uropathogen in the infant population. Regardless of O25b-ST131 or non-O25b-ST131 clones, CTX-M-14 accounts for majority of the ESBL genotype. The O25b-ST131 clone is not associated with more severe clinical disease, but it may make the diagnosis and selection of antimicrobials for treatment more challenging.

Escherichia coli ST131, an intriguing clonal group

In 2008, a previously unknown Escherichia coli clonal group, sequence type 131 (ST131), was identified on three continents. Today, ST131 is the predominant E. coli lineage among extraintestinal pathogenic E. coli (ExPEC) isolates worldwide. Retrospective studies have suggested that it may originally have risen to prominence as early as 2003. Unlike other classical group B2 ExPEC isolates, ST131 isolates are commonly reported to produce extended-spectrum β-lactamases, such as CTX-M-15, and almost all are resistant to fluoroquinolones. Moreover, ST131 E. coli isolates are considered to be truly pathogenic, due to the spectrum of infections they cause in both community and hospital settings and the large number of virulence-associated genes they contain. ST131 isolates therefore seem to contradict the widely held view that high levels of antimicrobial resistance are necessarily associated with a fitness cost leading to a decrease in pathogenesis. Six years after the first description of E. coli ST131, this review outlines the principal traits of ST131 clonal group isolates, based on the growing body of published data, and highlights what is currently known and what we need to find out to provide public health authorities with better information to help combat ST131.

Antimicrobial resistance in Asia: current epidemiology and clinical implications

Antimicrobial resistance has become one of the most serious public health concerns worldwide. Although circumstances may vary by region or country, it is clear that some Asian countries are epicenters of resistance, having seen rapid increases in the prevalence of antimicrobial resistance of major bacterial pathogens. In these locations, however, the public health infrastructure to combat this problem is very poor. The prevalence rates of methicillin-resistant Staphylococcus aureus (MRSA), macrolide-resistant Streptococcus pneumoniae, and multidrug-resistant enteric pathogens are very high due to the recent emergence of extremely drug-resistant gram-negative bacilli in Asia. Because antimicrobial options for these pathogens are extremely limited, infections caused by antimicrobial-resistant bacteria are often associated with inappropriate antimicrobial therapy and poor clinical outcomes. Physicians should be aware of the current epidemiological status of resistance and understand the appropriate use of antimicrobial agents in clinical practice. This review focuses on describing the epidemiology and clinical implications of antimicrobial-resistant bacterial infections in Asian countries.