Prevalence and molecular characterisation of carbapenemase-producing Enterobacterales in an outbreak-free setting in a single hospital in Uruguay

Abstract

Objectives: This study aimed to characterise all carbapenemase-producing enterobacteria (CPE) isolates obtained from an outbreak-free setting in Uruguay. Methods: We studied 12 CPE isolated from Hospital de Clínicas between 2012–2016. Bacterial identification and antibiotic susceptibility testing were performed using VITEK®2 and Sensititre or agar dilution, respectively. Antimicrobial resistance genes and mobile genetic elements were identified by PCR and sequencing. Multilocus sequence typing was performed for Klebsiella pneumoniae. Plasmid conjugation was assessed, plasmid size was estimated by S1-PFGE and plasmid incompatibility groups were sought by PCR. Results: Among 8364 enterobacteria, 12 CPE were isolated from urine, blood culture, wound, peritoneal fluid and punch samples. NDM-1 was the most prevalent carbapenemase, followed by VIM-2 and KPC-2. All isolates were resistant to gentamicin, cefotaxime, ceftazidime, trimethoprim/sulfamethoxazole, ciprofloxacin and imipenem and were susceptible to fosfomycin. We characterised six class 1 integrons: dfrA12–orfF–aadA2; aacA4–blaOXA-2–orfD; aadB–aadA2; dfrA1; aadB–blaOXA-10–aadA1; and blaVIM-2-dfrA7. An association between various aminoglycoside, β-lactam and fluoroquinolone resistance genes were observed, some of them located in transferable plasmids belonging to incompatibility groups IncC, IncHI1 and IncM1. We described a new composite transposon (assigned Tn6935) including blaNDM-1 flanked by two directly-oriented copies of a Tn3-like element ISKox2-like family transposase. The sequence types of K. pneumoniae isolates were ST11, ST14 and ST661. Conclusions: The presence of CPE is sporadic and could be due to measures taken by the Public Health Committee. Nevertheless, the coexistence of several resistance mechanisms and their presence in conjugative plasmids and high-risk clones is worrisome.

Keywords

• Carbapenemase
• Carbapenemase-producing Enterobacterales
• Plasmid incompatibility group