ABSTRACT
OBJECTIVES: The objectives were to determine the prevalence of colistin resistance in clinical isolates of Enterobacteriaceae, and to gain knowledge on the epidemiological and clinical features of the patients. METHODS: All colistin-resistant Enterobacteriaceae consecutively isolated from clinical samples in our institution from 2012 to 2015, were included in this cross-sectional study. Intrinsic-resistant species were excluded. Minimum inhibitory concentration was performed by gradient diffusion. Detection of plasmid-encoded colistin resistance genes mcr-1 and mcr-2 was performed by amplification. Epidemiological and clinical features were reviewed. RESULTS: Of 13579 Enterobacteriaceae isolates, 91 were colistin-resistant. The overall prevalence of colistin resistance was 0.67%. The rates were higher in Enterobacter cloacae (4.2%) than Escherichia coli (0.5%) and Klebsiella pneumoniae (0.4%). One third of the isolates were multi-drug resistant (MDR). While mcr-2 was not detected, mcr-1 was detected only in E. coli. Regarding these infections, 23% were community-acquired. 89% of the patients had not received colistin previously. There were no significant differences between infections caused by mcr-1 and non-mcr-1-carrying isolates. CONCLUSIONS: Colistin resistance was not restricted to MDR isolates and to clinical settings. Most patients had no record of previous administration of colistin.
Subject(s)
Anti-Bacterial Agents/pharmacology , Colistin/pharmacology , Drug Resistance, Bacterial , Enterobacteriaceae Infections/drug therapy , Enterobacteriaceae Infections/epidemiology , Enterobacteriaceae/drug effects , Adolescent , Adult , Aged , Aged, 80 and over , Analysis of Variance , Anti-Bacterial Agents/therapeutic use , Child , Colistin/therapeutic use , Cross-Sectional Studies , Enterobacteriaceae/isolation & purification , Female , Humans , Male , Microbial Sensitivity Tests , Middle Aged , Prevalence , Prospective Studies , Retrospective Studies , Spain/epidemiology , Tertiary Care Centers , Young AdultABSTRACT
Colistin resistance was detected in 53 of 10,011 Escherichia coli (0.5%) by prospective phenotypic testing of consecutive clinical isolates in a single hospital in Barcelona, Spain (2012-15). The mcr-1 gene was retrospectively identified by PCR and sequencing in 15 of 50 available isolates. Each isolate had a unique PFGE pattern except for two. This clonal diversity supports the hypothesis of horizontal dissemination of the mcr-1 gene in the local study population.
Subject(s)
Anti-Bacterial Agents/pharmacology , Colistin/pharmacology , Drug Resistance, Bacterial/genetics , Escherichia coli Infections/drug therapy , Escherichia coli/drug effects , Escherichia coli/isolation & purification , Adolescent , Adult , Aged , Aged, 80 and over , Child , Electrophoresis, Gel, Pulsed-Field , Escherichia coli/genetics , Escherichia coli Infections/epidemiology , Genotype , Humans , Microbial Sensitivity Tests , Middle Aged , Phenotype , Polymerase Chain Reaction , Prevalence , Prospective Studies , Spain/epidemiology , Young AdultABSTRACT
Mortality from bloodstream infections (BSIs) correlates with diagnostic delay and the use of inappropriate empirical treatment. Early PCR-based diagnosis could decrease inappropriate treatment, improving patient outcome. The aim of the present study was to assess the clinical utility of this molecular technology to diagnose BSIs. We assessed a new dual-priming oligonucleotide-based multiplex PCR assay, the Magicplex Sepsis Test (MST) (Seegene), along with blood culture (BC). A total of 267 patients from the intensive care unit and haematology and emergency departments were enrolled. Clinical data were also used by physicians to determine the likelihood of infection. Ninety-eight (37â%) specimens were positive: 29 (11â%) by both the MST and BC, 29 (11â%) by the MST only, and 40 (15â%) by BC only. The proportion of agreement between the two methods was 73â% (Cohen's κ: 0.45; 0.28-0.6; indicating fair to moderate agreement). According to clinical assessment, 63 (64â%) positive specimens were considered BSIs: 23 (36â%) were positive by both the MST and BC, 22 (35â%) were positive only by BC, and 18 (29â%) were positive only by the MST. Thirty-eight (14â%) positive specimens by the MST and/or BC were considered as contaminants. Of 101 specimens collected from patients receiving antibiotics, 20 (20â%) were positive by the MST and 32 (32â%) by BC. Sensitivity and specificity were 65â% and 92â%, respectively, for the MST and 71â% and 88â%, respectively for BC. We concluded that the MST shows a high specificity but changes in design are needed to increase bacteraemia detection. For viability in clinical laboratories, technical improvements are also required to further automate the process.
Subject(s)
Bacteremia/diagnosis , Multiplex Polymerase Chain Reaction/methods , Humans , Oligonucleotides/genetics , Prospective Studies , Sensitivity and SpecificityABSTRACT
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