Extended spectrum B-lactamase and plasmid mediated AmpC resistance in clinical isolates of escherichia coli from the central hospital of Maputo, Mozambique.

Abstract

Antibiotic resistance is one of the main public health problems worldwide, reducing treatment options and increasing morbidity and mortality. The production of extendedspectrum β-lactamases (ESBLs), plasmid mediated (pAmpC) β-lactamases are the most important resistance mechanisms that hamper antimicrobial treatment of infections caused by Enterobacteriaceae. This study describes the detection and characterization of pAmpC- and/or ESBL-producing clinical isolates of Escherichia coli (n=230) from urine and blood samples at the Central Hospital of Maputo, Mozambique from midAugust to mid-November 2015. Antimicrobial susceptibility testing was performed by the disc diffusion method. Isolates with reduced susceptibility to cefotaxime and/ or ceftazidime (n=75) were subjected to phenotypic AmpC- and/or ESBL testing as well as PCR-detection of blaCTX-M, blaTEM, blaSHV, blaCMY, blaMOX, blaFOX and blaDHA. A total of 75/230 (32.6 %) isolates were ESBL positive, and twenty-five of these were pAmpC positive. The most prevalent ESBL and pAmpC were CTX-M (77%) and FOX (32%), respectively. Most CTX-M negative ESBL-strains were blaSHV positive indicating a SHV-ESBL-type. The presence of co-resistance (R and I) to clinically important antibiotics were also frequent; blood ciprofloxacin (CIP; n= 12/17: 70.6%), gentamicin (GEN; n= 8/17: 47.1 %) and trimethoprim-sulfamethoxazole (SXT; n= 17/17; 100%) and urine CIP (n=40/58; 68.9%), GEN (n= 27/58; 46.5 %) and SXT (n= 55/58; 94.8%). Multidrug resistance was observed in 17/17 (100 %) and 58/58 (100 %) blood and urinary isolates, respectively. ERIC-PCR analysis revealed a large genetic diversity of strains with some minor clusters indicating intra hospital spread. The study has shown that: (i) a large proportion of clinical isolates of E. coli from the urinary tract and blood cultures from the Central Hospital are pAmpC and/or ESBLproducing. (ii) CTX-Ms and FOX were the dominant ESBL- and pAmpC-types, respectively. (iii) All ESBL- and pAmpC-producing strains were MDR-strains only susceptible to antibiotics that are not easily available in the current location. The overall findings strongly support the urgent need for strengthened and rapid diagnostic services to guide correct treatment of serious life-threatening infections and improved infection control measurements.