الفهرس 
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Abstract
Carbapenem-resistant Enterobacteriaceae (CRE) are emerging as a global threat. They cause serious infections in debilitated and immunocompromised patients, in association with prolonged hospital stays and increased mortality rates, ranging from 24% to as high as 70%, depending on the study population. They can colonize or infect not only those patients who are debilitated, but also those who were previously healthy and became colonized or infected in healthcare settings practicing poor infection control.
The plasmid-borne carbapenemase gene blaKPC is the predominant mechanism conferring carbapenem resistance.
Over the past 10 years, dissemination of Klebsiella pneumoniae carbapenemase (KPC) has led to an increase in the prevalence of carbapenem-resistant Enterobacteriaceae (CRE).
Detection of KPC-harboring organisms remains challenging. Difficulties in KPC detection may lead to an underestimation of the true prevalence and incidence of KPC-producing organisms.
Rectal swab culture is the best accepted method for detecting stool carriage. The standard method for detecting
C
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colonization of patients with carbapenemase-producing organisms is to culture rectal or perianal swab samples on differential and selective agar plates, such as MacConkey agar, sometimes supplemented with a carbapenem disk, followed by antimicrobial susceptibility testing or with carbapenems incorporated within MacConkey agar during preparation.
Confirmatory testing for KPC-producing bacteria is recommended in geographical locations where Entero-bacteriaceae are noted to have decreased susceptibility to carbapenems or resistance to most non-carbapenem beta-lactams by routine testing.
The aim of the present study was to evaluate different screening agar plates for the detection of Klebsiella Pneumoniae carbapenemase (KPC) producing Carbapenem Resistant Enterobacteriaceae (CRE) in ICU patients.
In the present study, rectal swabs from 138 patients (3 swabs from each patient) were collected from different Intensive Care Units (Geriatric, Internal Medicine, Surgery and Neurosurgery) over the period from April 2014 to September 2014 (one swab for real time PCR, stored in 5 ml trypticase soy broth at 20°C, and the other two swabs used immediately for phenotypic methods).
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The microbiological work and PCR were carried out at the central Microbiology Laboratory, Ain Shams University Hospital.
Swabs from the 138 patints were subjected to the following:
1- Phenotypic detection of Carbapenemase production by culturing on:
a. MacConkey agar supplemented with 1μg/ml imipenem.
b. MacConkey agar supplemented with 1μg/ml ertapenem.
c. MacConkey agar with 10μg antibiotic discs of imipenem, meropemen and ertapenem.
d. MacConkey agar as primary culture followed by antibiotic susceptibility of the recovered isolates using imipenem (10μg), meropenem (10μg) and ertapenem (10μg) discs according to Clinical Laboratory Standard Institute 2012 (CLSI 2012).
2- Confirmation of Carbapenemase production by Modified Hodge test from isolates recovered from a, b and c.
3- Only 100/ 138 swabs were subjected to PCR for detection of blaKPC gene.
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One hundred and two (102/138) patients were carriers of CRE by MacConkey agar supplemented with ertapenem of whom 95/102 were CPE by MHT.
Seventy four out of one hundred (74%) had blaKPC gene by PCR.
MacConkey agar supplemented with ertapenem showed sensitivity of 86.5% in relation to PCR, and 100% in relation to MHT.
ManConkey agar supplemented with imipenem showed sensitivity of 78.4% in relation to PCR, and 90.6% in relation to MHT.
ManConkey agar with carbapenem disks showed sensitivity of 79.7% in relation to PCR, and 92.2% in relation to MHT.
All used screening methods showed the same specificity in relation to PCR (73.1%) and MHT (80.6%).
There was significant difference (P< 0.05) between MacConkey agar supplemented with imipenem and MacConkey agar supplemented with ertapenem as regard their sensitivity with PCR as reference test.
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Moreover, there was a significant difference (P< 0.05) between MacConkey supplemented with ertapenem and MHT as regard their sensitivity with PCR as reference test.