Introduction: Carbapenemase-producing Enterobacterales (CPE) have emerged as a substantial cause of morbi-mortality worldwide, with a prevalence of approximately 5% in areas with high endemicity. However, available data may not be representative of developing countries, such as Ecuador. In this study, the incidence of CPE in Ecuador and risk factors for infection/colonisation were evaluated.
Methodology: A prospective cohort study was performed from February to April 2016 in seven intensive-care units of Guayaquil, Ecuador. Samples were processed according to the Centers for Disease Control and Prevention laboratory protocol and the CHROMagar mSuper CARBA agar method. Resistance to carbapenems was defined according to Clinical and Laboratory Standards Institute breakpoints. A modified carbapenemase inactivation method was used to identify carbapenamase production phenotypically with molecular confirmation by multiplex polymerase chain reaction.
Results: In total, 640 patients were enrolled. The incidence of CPE was 36.4% (N = 233). A multivariate analysis indicated that several factors were associated with CPE acquisition, included a long intensive care unit stay (OR 1.05; 95% CI 1.03–1.08; p < 0.01), tracheostomy (OR 3.52; 95% CI 1.90–6.75; p < 0.01), hospitalisation 3 months prior to admission (OR 2.07; 95% CI 1.17–3.71; p < 0.01), vancomycin use (OR 3.31; 95% CI 2.02–5.18; p < 0.01), and macrolide use (OR 3.31; 95% CI 1.43–7.76; p < 0.01).
Conclusions: Macrolide use was a risk factor for CPE acquisition. This association should be evaluated further, especially in developing countries.
Background
In low‐ and middle‐income countries, the use of colistin in therapeutic regimens is common, to treat infections produced for Carbapenemase‐producing
Enterobacterales
(CPE) due to limited access to the recently discovered‐approved antibiotics. Furthermore, the technical limitations to perform colistin susceptibility tests make it difficult to assess the suitability of this treatment for each patient, as well as to monitor the rates of resistance. In the present study, we describe the use of agar dilution using a unique colistin concentration of 3 μg/ml to discriminate isolates with colistin resistance in CPE obtained from clinical samples.
Methods
Clinical Laboratory Standards Institute (CLSI) colistin broth microdilution method and dilution agar with a colistin concentration of 3 μg/ml were performed in 168 isolates of CPE obtained from clinical samples in Guayaquil, Ecuador. Broth microdilution was considered our gold standard using CLSI breakpoints as reference (≤2 μg/ml intermediate and ≥4 μg/ml resistant). Categorical agreement was defined as obtaining a reading within the same category with both methodologies.
Results
Isolates obtained from respiratory samples were the most prevalent (26.19%;
n
= 44).
Klebsiella pneumoniae
was the predominant specie (94.04%;
n
= 158). KPC‐like carbapenemase was present in all the isolates, and interestingly, colistin resistance was not mediated by MCR‐1 production. Categorical agreement between both methods resulted in 97.02%.
Conclusion
We propose the use of dilution agar with a colistin concentration of 3 μg/ml, as a valid method for screening colistin resistance in low‐ and middle‐income countries to monitor resistance and to perform epidemiological studies.
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