Resistance to quinolones, cephalosporins and macrolides in Escherichia coli causing bacteremia in Peruvian children

Noemí Palma, Maria J Pons, Cláudia Gomes, Judit Mateu, Maribel Riveros, Wilfredo García, Jan Jacobs, Coralith García, Theresa J Ochoa, Joaquim Ruiz

Research output: Contribution to journalA1: Web of Science-articlepeer-review


OBJECTIVE: To characterize the β-lactam, quinolone and macrolide resistance levels and mechanisms in 62 Escherichia coli isolates causing children bacteremia.

METHODS: Minimal inhibitory concentration of ciprofloxacin, nalidixic acid (NAL) and azithromycin was determined in presence and absence of Phe-Arg-β-Naphtylamyde. Additionally, the susceptibility levels to other 14 antimicrobial agents was established. Extended Spectrum β-lactamases (ESBLs) were identified, while mutations in gyrA and parC genes, presence of transferable mechanisms of quinolone-resistance (TMQR) and macrolide-resistance (TMMR) was also determined.

RESULTS: Forty-Nine (79.0%) isolates were multidrug resistant. High proportions of resistance to ampicillin (93.6%), NAL (66.1%) and cotrimoxazole (64.5%) was observed. No isolate showed resistance to carbapenems and only two were resistant to nitrofurantoin. Twenty-seven isolates carried ESBL-encoding genes: 2 blaSHV-12, 13 blaCTX-M-15, 4 blaCTX-M-2, 6 blaCTX-M-65 and 2 non-identified ESBLs. In addition 27 blaTEM-1 and 9 blaOXA-1-like genes were detected. All quinolone-resistant isolates showed target-mutations, while TMQR were present in 4 isolates; Efflux pumps played a role in the constitutive NAL-resistance levels. The association between quinolone-resistance and ESBL-production was significant (P=0.0011). The mph(A) gene was the most frequent TMMR (16 isolates), in addition msr(A) and erm(B) genes were detected. Only 1 TMMR carrying isolate (presenting the mph(A) and the erm(B) genes concomitantly) remained azithromycin-resistant when efflux pumps were inhibited.

CONCLUSIONS: A variety of ESBL encoding genes and widespread of blaCTX-M-15 in the area has been showed. The role of efflux pumps in azithromycin resistance needs to be further evaluated, as well as an effective control in the use of antimicrobial agents.

Original languageEnglish
JournalJournal of Global Antimicrobial Resistance
Pages (from-to)28-33
Number of pages6
Publication statusPublished - 2017


  • Journal Article


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