Abstract - Detection of extended-spectrum & Plasmid-mediated AmpC Beta-Lactasmases in nosocomial Klebsiella isolates

摘要

The coexistence of enzymes in the same Klebsiella strain may result in false-negative tests for the detection of ESBLs as pAmpCs resist inhibition by clavulanic acid so masking ESBL presence. This study was to highlight the detection rates of ESBLs and pAmpCs by using phenotypic method; MAST 4-disc test and multiplex polymerase chain reaction (PCR) method. In addition, it aimed to evaluate the sensitivity of the phenotypic method in detection of these enzymes. Methods Klebsiella isolates were collected from clinical samples in different wards in Zagazig University Hospitals. The antibiogram of these bacteria was determined by disc diffusion method. The presence of ESBLs and pAmpCs within the isolates was determined using the phenotypic MAST 4-disc test followed by a multiplex PCR method. Results In total, 38 Klebsiella pneumoniae strains were evaluated. Among these isolates, 65.8% were ESBL producers, 2.6% were pAmpC producers, and 31.6% were neither ESBL nor pAmpC producers. The most frequent genotype of ESBL was SHV (84%); followed by TEM (44%) pAmpC producers were of DHA genotype. The distribution of different ESBL genotypes was SHV (84%), TEM (44%), CTX-M II genotype (28%) and followed by SHV and CTX-M IV genotype (24%). Using multiplex PCR as a reference method, MAST 4-disc test was of 92% sensitivity and 86.7% specificity. Conclusion A rising alarm of ESBL producing strains among K. pneumoniae isolates. The exact detection of ESBLs in isolates that produce both enzymes is important for both treatment and epidemiology. Volume 03, Number 01 (2013)