Clinical study on the distribution of ESBL genotypes in drug-resistant escherichia coli in urinary tract infection
Objective:Genotyping of non-extended-spectrum β-lactamase(ESBL)and ESBL-producing Esche-richia coli strains isolated from urinary tract infections(UTIs)and determination of uropathogenic Escherichia co-li(UPEC)strain lineages.Methods:Four hundred and ninety-nine strains of E.coli from the urine of UTI-diag-nosed patients were collected from the clinical laboratory of Nanjing First Hospital.The isolates were obtained from different wards of our hospital from November 2018 to March 2022,including inpatients in urology,neph-rology,ICU,internal medicine,pediatrics.Polymerase chain reaction(PCR)was performed using ampicillin-re-sistant E.coli isolates to study the beta-lactamase gene.All isolates were subjected to multilocus sequence typing(MLST)by multiplex PCR assay.Results:Drug resistance to ampicillin,ciprofloxacin,or trimethoprim-sulfame-thoxazole was found in 244(49％)isolates;128(26％)isolates were multidrug resistant(MDR),including 34(7％)ESBL-producing strains.The probability of isolation of MDR E.coli and ESBL-producing E.coli was sig-nificantly higher in subjects＞59 years old than those in other age groups(P＜0.01).MLST analysis showed that the drug-resistant isolates mainly belonged to STs of phylogeny D and B2.Among them,CC69(n=75)was the most common,and all isolates were included in ST69(n=75,100％).CC131(n=48),including ST131(n=42,86％),ST2279(n=4,8％),ST2657(n=1,2％),and ST1195(n=1,2％)followed.Among the 255 suscepti-ble strains,only 2 ST69 strains and 3 ST131 strains were detected.Of the 34 ESBL-producing isolates,31(91％)contained the blaCTX-M type gene;17(55％)contained blaCTX-M-15,and 9(29％)contained blaCTX-M-8.Conclusion:Enterobacteriaceae detected from UTI has a high incidence of ESBL and increased resistance to com-monly used antibiotics.Increased resistance is associated with UPEC isolates belonging to ST69 and ST131.
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