الفهرس 
Klebsiella PneumoniaeOnly 14 pages are availabe for public view
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Abstract
Carbapenems resistance among Enterobacteriaceae, is an emerging problem worldwide. Several resistance mechanisms have been reported to circumvent the efficacy of carbapenems. Expression of carbapenemase, porin loss or efflux pumps, which pump out any drugs or harmful chemicals that enter through the porins and alterations in PBP, are all associated with carbapenem resistance in Gram-negative rods.
KPC-type carbapenemases (Class A carbapenemases) which include blakpc are being an increasingly important mechanism of acquired resistance to carbapenems and other β-lactams. These resistance determinants are present in K. pneumoniae and other gram-negative pathogens.
The KPC enzyme confers resistance to all β-lactam agents including penicillins, cephalosporins, monobactams, and carbapenems.
The present study aimed to determine carbapenem resistance among klebsiella pneumoniae isolates by routine disc diffusion test and E- test, determine carbapenemase production by Modified hodge test and study the presence of blakpc gene in carbapenem-resistant and carbapenem sensitive klebsiella pneumoniae isolates.
The study was conducted at the National institute of diabetes and endocrinology in the period from September 2012 to June 2013. The study included 50 klebsiella pnumoniae isolates obtained from specimens reaching the microbiology laboratory for routine culture and susceptibility testing. Isolates were obtained from 36 (72%) urine samples and 14 (28%) wound swabs.
All 50 isolates were subjected to testing of antibiotic susceptibility to three carbapenems by the Kirby-Bauer disc diffusion method. It showed that 13/50 (37%) isolates were resistant to both meropenem and ertapenem while only 11/50 (22%) isolates were resistant to imipenem and 2 (4%) were in the intermediate zone.
The 50 isolates were subjected to determination of minimum inhibitory concentration (MIC) to ertapenem using E-test. Results were interpreted according to (CLSI, 2012): 11out of 50 (22%) had MIC ≥ 2 μg/ml and recorded as resistant strains, 2 (4 %) had MIC > 0.5 μg/ml and < 2 μg/ml and were recorded as intermediate sensitive strains, 37 out of 50 isolates (74%) showed MIC ≤ 0.5 μg/ml so they were considered susceptible to ertapenem.
Ertapenem sensitivity tests revealed that there was a discrepancy between the results of E-test and disc diffusion method in two strains. The two strains were reported resistant by disc diffusion method and intermediate sensitive by E-test.
Modified hodge test for detection of carbapenemase has been done for all 50 isolates, 13 out of 50 (26%) showed positive modified hodge test while 37 out of 50 were negative (74%).
Modified hodge test was negative for all isolates sensitive to ertapenem by disc diffusion and E- test. MHT was positive for all isolates resistant to ertapenem by disc diffusion and E- test with 100% agreement.
Twenty-six k.pneumoniae isolates were subjected to PCR for detection of blakpc gene. Thirteen confirmed carbapenem resistant isolates by disc diffusion, E-test and MHT and 13 confirmed carbapenem sensitive isolates by the same tests. All of these 26 isolates were negative for blakpc gene.