Determination of Resistance Pattern of Plasmid-Mediated AmpC

The widespread use of β -lactam antibiotic has lead to the development of resistance to this group of antibiotics in bacterial pathogens due to β -lactamase production. This study was undertaken to determine the AmpC β -lactamase production in pathogens isolated from hospitalized patients at selected university hospitals of Tehran. Non-repeat clinical isolates (154) from clinical specimens of selected hospital were taken. Disk agar diffusion and minimum inhibitory concentration (MIC) with β -lactam antibiotic included Ceftazidim, Ceftriaxon and Cefepim and Clavulanic acid as a β -lactamase inhibitor for detection of extended spectrum β -lactamase (ESBLs) producing organisms w ere done. In addition, the susceptibility of these organisms to Cefoxitin was examined. All isolates were examined by Multiplex PCR method for finding the different kind of gene family encoded AmpC β -lactamases Isolates had divided in three group included of P+, P+C+, P+C- based on ESBLs phenotypic test criteria with 57.15% (n=88), 53.9% (n=83) and 3.25% (n=5) respectively. Isolates that their result became P+C+ and P+C- were selected and the Multiplex PCR for them were done. The results of molecular testing showed that 5.7% of isolates, in the other hand 5 strains of E. coli were positive for AmpC β -lactamase. This is the first report of AmpC β -lactamase producing bacteria from Iran. If the type of β -lactamase produced by the pathogen could be detected along with antibiogram before administrating the β -lactamase drug to the patient therapeutic failure might be avoided. Because of significance of these organisms in produce nosocomial infection and in order to prevent them from spread, we need to more study for showing the actual prevalence of them.