Dataset Information

Use of Ancillary Carbapenemase Tests To Improve Specificity of Phenotypic Definitions for Carbapenemase-Producing Enterobacteriaceae.

ABSTRACT: Carbapenemase-producing Enterobacteriaceae (CPE) are a significant threat to public health. In 2015, CDC revised the surveillance definition for CPE to include all Enterobacteriaceae resistant to any carbapenem tested. However, this definition is associated with poor specificity. We evaluated the performance of this definition, compared to carbapenemase PCR, for a collection of 125 Enterobacteriaceae We also investigated the impact of ancillary testing for carbapenemase of isolates that met the CDC CPE surveillance definition. The two ancillary tests evaluated were the Xpert Carba-R assay, a molecular test, and the carbapenem inactivation method (CIM). Two variables were evaluated for the CIM: suspension of organisms in double-distilled water (ddH2O) versus tryptic soy broth (TSB) to incubate disks, and incubation of plates for 6 h versus 18 to 20 h. The sensitivity and specificity of the Carba-R assay were 100% compared to the results of in-house PCR. The sensitivities of the CIM performed with TSB were 94.6% when read at 6 h and 97.7% when read at 18 to 20 h; the sensitivities with ddH2O were 88.0% when read at 6 h and 93.0% when incubated for 18 to 20 h. The specificity was 100% for all variables tested. Without ancillary testing, the sensitivity of the CDC definition was 98.9% for CPE, and the specificity was 6.1%. Testing isolates that screened positive by the CDC definition with the Xpert Carba-R did not change the sensitivity, and it improved the specificity to 100%. Similarly, the use of the CIM (TSB and 18 to 20 h of incubation) to confirm screen-positive isolates resulted in a sensitivity of 95.6% and specificity of 100%.

SUBMITTER: Miller SA

PROVIDER: S-EPMC5442539 | biostudies-other | 2017 Jun

REPOSITORIES: biostudies-other

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Use of Ancillary Carbapenemase Tests To Improve Specificity of Phenotypic Definitions for Carbapenemase-Producing Enterobacteriaceae.

Miller Shelley A SA Hindler Janet A JA Chengcuenca Angelo A Humphries Romney M RM

Journal of clinical microbiology 20170329 6

Carbapenemase-producing Enterobacteriaceae (CPE) are a significant threat to public health. In 2015, CDC revised the surveillance definition for CPE to include all Enterobacteriaceae resistant to any carbapenem tested. However, this definition is associated with poor specificity. We evaluated the performance of this definition, compared to carbapenemase PCR, for a collection of 125 Enterobacteriaceae We also investigated the impact of ancillary testing for carbapenemase of i ...[more]

PMID: 28356417

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Project description:BackgroundCarbapenem-resistant Enterobacteriaceae (CRE) are responsible for worldwide outbreaks and antibiotic treatments are problematic. The polysaccharide poly-(?-1,6)-N-acetyl glucosamine (PNAG) is a vaccine target detected on the surface of numerous pathogenic bacteria, including Escherichia coli. Genes encoding PNAG biosynthetic proteins have been identified in two other main pathogenic Enterobacteriaceae, Enterobacter cloacae and Klebsiella pneumoniae. We hypothesized that antibodies to PNAG might be a new therapeutic option for the different pan-resistant pathogenic species of CRE.MethodsPNAG production was detected by confocal microscopy and its role in the formation of the biofilm (for E. cloacae) and as a virulence factor (for K. pneumoniae) was analysed. The in vitro (opsonophagocytosis killing assay) and in vivo (mouse models of peritonitis) activity of antibodies to PNAG were studied using antibiotic-susceptible and -resistant E. coli, E. cloacae and K. pneumoniae. A PNAG-producing strain of Pseudomonas aeruginosa, an organism that does not naturally produce this antigen, was constructed by adding the pga locus to a strain with inactive alg genes responsible for the production of P. aeruginosa alginate. Antibodies to PNAG were tested in vitro and in vivo as above.ResultsPNAG is a major component of the E. cloacae biofilm and a virulence factor for K. pneumoniae. Antibodies to PNAG mediated in vitro killing (>50%) and significantly protected mice against the New Delhi metallo-?-lactamase-producing E. coli (P?=?0.02), E. cloacae (P?=?0.0196) and K. pneumoniae (P?=?0.006), against K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae (P?=?0.02) and against PNAG-producing P. aeruginosa (P?=?0.0013). Thus, regardless of the Gram-negative bacterial species, PNAG expression is the sole determinant of the protective efficacy of antibodies to this antigen.ConclusionsOur findings suggest antibodies to PNAG may provide extended-spectrum antibacterial protective activity.

Dataset Information

Use of Ancillary Carbapenemase Tests To Improve Specificity of Phenotypic Definitions for Carbapenemase-Producing Enterobacteriaceae.

Publications

Use of Ancillary Carbapenemase Tests To Improve Specificity of Phenotypic Definitions for Carbapenemase-Producing Enterobacteriaceae.

Similar Datasets

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