Rapid detection of carbapenemases producing Enterobacteriaceae (CPE) by ChromaticTM CPE media in intensive care units in Ain Shams University Hospitals

Document Type : Original Article


1 Medical Microbiology and Immunology Department, Faculty of medicine, 6 October Univeristy, Cairo, Egypt

2 Medical Microbiology and Immunology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt

3 Clinical pathology department , Faculty of Medicine, Ain Shams University, Cairo, Egypt


Background: The evolution and springing up of carbapenemase-producingEnterobacteriaceae (CPE) threatens worldwide health. The capability of carbapenemases to degrade all β-lactam antibiotics leads to less antibiotics retaining activity against infections caused by CPE that are associated with high mortality and bad prognosis. There is an urgent need to define robust standardized screening methods for the effective detection of CPE in order to control their spread. This study aimed to detect the efficiency of Chromatic TM CPE medium in identifying CRE directly from ICU clinical samples. Methods: A Cross section study was conducted at intensive care units and Medical Microbiology and Immunology laboratory, Faculty of medicine, Ain Shams university. The sample was directly inoculated on CRE chromagar plate and incubated at 35°C aerobically. Isolation and identification of CPE was performed according to Manual of Clinical Microbiology 2019 then antimicrobial susceptibility test by Kirby-Baur disc diffusion. The sensitivity and specificity of CRE screening by CRE chromogenic media were detected using Modified carbapenemase inactivation method (mCIM) as the standard method. Results: One hundred and fifty-eight isolates were obtained from hospitalized ICU patients in Ain shams university hospital between April to November 2022. There were different types of samples, the most common one was sputum. Among 71 isolates grew on blood and MacConkey agar media, 59 (83.15%) showed growth on chromogenic media while 12 (16.9%) showed no growth on chromogenic media. Fifty-four (76.1%) showed MDR Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii. Among 54 MDR isolates, 50 (92.6%) were positive carbapenemase production, while 4 (7.4%) were negative carbapenemase production using mCIM test as confirmatory test. The sensitivity of chromogenic media was 98%, specificity was 50% in all isolates and the accuracy of the test was 94.4%. While the sensitivity of chromogenic media in all Enterobacteriaceae was 96.9%, specificity was 33.3%. Conclusion: This study revealed that CRE chromogenic is highly sensitive in the screening of CRE detection. It efficiently saves more time in identifying CRE as compared to mCIM method. The use of a single chromogenic medium can reduce the cost of sample processing and be an effective tool for rapid detection of CRE. Accurate and fast detection of patients colonized by CPEs is clinically important in applying proper infection control precautions.


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