الفهرس | Only 14 pages are availabe for public view |
Abstract Carbapenem Resistant Enterobacteriaceae (CRE) has become an increasingly recognized cause of infection during the past decade, likely because of the emergence of carbapenemase-producing strains. The ability to limit the spread of these pathogens will require effective laboratory methods to rapidly identify patients infected with these organisms. The objective of this study was to evaluate the Carbapenem inactivation assay (Modified Hodge Test) as a confirmatory test for carbapenemase production among clinical isolates of Enterobacteriaceae. Seventy samples of urine were collected during a month, from May ٢٠١١ to June ٢٠١١from patients with indwelling urinary catheters for more than ٤٨ hours of catheterization (to reach a final number of Sixty one Gram negative rod isolates ). All patients were hospitalized in different ICUS of Ain Shams University and Kobry El kobba Military Hospitals. All urine samples were centrifuged, and then the deposit of each sample was inoculated onto the surface of different culture media; Blood, MacConkey’s agar and the new chromogenic Uriselect ٤ media. All inoculated media were incubated aerobically at ٣٧oC for ٢٤ hours. The growing colonies were identified by standard microbiological techniques. The sixty one isolates included in this study with Gram negative rod, morphology and negative oxidase test results were completely identified down to species level using the overnight ID ٣٢ E strips. Thirty six isolates of them were E.coli (٥٩٫٠٢٪) while ٢٥ isolates were Klebsiella pneumoniae (٤٠٫٩٨٪).Twenty eight E.coli isolates (٧٨%) among ٣٦ E.coli isolates were identified as ESBL producers using the standard disk diffusion method. while a total number of ١٦ E.coli isolates (٤٤٫٤٤٪) were identified as ESBLs by disk approximation method. Eleven Klebsiella pneumoniae isolates (٤٤٪) among ٢٥ Klebsiella pneumoniae isolates were identified as ESBL producers using the disk diffusion method. while ١٥ Klebsiella pneumoniae isolates (٦٠٪) were identified as ESBLs by disk approximation method. The comparison between the disc diffusion and the disc approximation methods for detection of ESBLs among the study isolates showed ٦٢٪ rate of positive agreement. As regards detection of CRE, disc diffusion method identified ١٨ isolates (١١ E.coli and ٧ K. pneumoniae) as resistant. The Sensitivity, Specificity, positive predictive value and negative predictive value of Disk diffusion test in correlation with MIC as a standard test for detection of CRE isolates were ١٠٠٪, ٨٦%, ٦١% and١٠٠٪ respectively. All Enterobacteriaceae isolates were tested for carbapenemases production using The Modified Hodge Test. Eight (٢٢٫٢٢٪) among ٣٦ E.coli isolates were positive for the Modified Hodge testing. While ٣ out of the ٢٥ Klebsiella pneumoniae isolates (١٢٪) were positive for carbapenemases production detected by the Modified Hodge testing. All isolates giving positive MHT were identified as being resistant to imipenem by tube dilution method (MIC ≥٤ μg/mL).MHT showed high performance quality in comparison to tube dilution method for detection of CRE (١٠٠٪ for sensitivity, specificity, PPV and NPV). |