PCR detection of PER &VEB &SHV and TEM β-lactamases in multidrug resistant P. aeruginoasa isolated from wound infections in two hospitals of Tehran

Class A serine beta-lactamases such as SHV, TEM, PER and VEB are among the most important resistance determinants emerging in gram negative bacterial pathogens. PER betalactamase is an enzyme of notable clinical importance due its ESBL (extended spectrum beta-lactamases) activity and fully characterized in P. aeruginosa. The present investigation was under taken to assess theprevalence of beta-lactamase genes belonging to SHV, TEM, PER and VEB in P. aeruginosa isolates from wound infections in two hospitals of Tehran. Totally 100 isolates of Multi Drug Resistant P. aeroginosa from wound infections were collected over one year period in two hospitals of Tehran. Susceptibility to antibiotics and MICs for ceftazidime and imipenem of these 100 isolates were assessed using disc diffusion and microdilution methods, respectively. Isolates showing MIC≥16 microgram/ml for ceftazidime were subjected to PCR using four primer sets including SHV, TEM, PER and VEB types of beta-lactamases. Only 6 of 100 studied isolates showed MIC≥4 for imipnem. Resistance to ceftazidime was determined in 42% of the isolates and 46% of the isolates showed MIC≥16 microgram/ml for ceftazidime.PCR assay indicated that out of 46 isolates showing MIC≥16 microgram/ml for ceftazidime, 28%, 11%, 13% and 11% were positive for SHV, TEM, PER and VEB beta-lactamase genes. Imipenem was the most effective antibiotic against multidrug resistant P. aeroginosa isolates from wound infections in this research. SHV beta-lactamase was more observed than three other studied genes among the isolates recovered from wound in two studied hospitals of Tehran. It is the first report ofbla PER and bla VEB in P. aeruginosa in Iran.