Detection of Plasmid Mediated AmpC alpha-Lactamases in Nosocomial Isolates of Klebsiella pneumoniae at Mansoura University Hospitals

ABSTRACT

Plasmid-mediated AmpC alpha-lactamases [pAmpC] have been discovered most frequently in Klebsiella pneumoniae. At this time, there is no st and ardized phenotypic method for the screening and detection of AmpC enzymes. The aim of the present study was to evaluate three phenotypic methods [modified three dimensional test, AmpC test and Hodge test] to detect pAmpC, to determine the rate of pAmpC in nosocomial isolates of Klebsiella pneumoniae from six hospitals in Mansouraandstudy antibiotic sensitivity pattern for isolates carrying pAmpC. A total of 112 consecutive nosocomial isolates of Klebsiella pneumoniae were included in the study. The presence of pAmpC was evaluated by cefoxitin screening test, modified three dimensional test, Hodge test, AmpC disc and multiplex polymerase chain reaction. Antibiotic susceptibility test was done by disc diffusion method for Klebsiella pneumoniae isolates carrying pAmpC gene. Phenotypic tests showed that three dimensional test, was the best regarding sensitivity and specificity when compared to Hodge test, AmpC disc. The multiplex PCR detect pAmpC in 54 [48%] isolates, DHA family in 34 [63%] isolates, followed by gene family ACC family in 17 [31.5] and both DHAandACC in three [5.6%] isolates. All isolates were resistant to third generation cephalosporins, 57% of isolates were sensitive to imipenem and 100% of isolates were sensitive to tigycyclin. Conclusions: pAmp C was detected in 48% of the study isolates. The most common pAmp C was the DHA family. tigycyclin is the most effective antibiotics in all isolates carrying p AmpC