detection of <italic>blaspm-1 </italic>metallo-?-lactamase gene in imipenem-resistant <italic>pseudomonas aeruginosa</italic> strains isolated from hospitalized patients in isfahan hospitals

Background]<italic>pseudomonas aeruginosa</italic> is an opportunistic human pathogen, which causes serious problems especially in people who have immunodeficiency. recently, metallo?lactamase (mbls) resistance in this bacterium has led to some difficulties in treating bacterial infections. the <italic>blaspm1 </italic>is one of the mbl gene families, which induces resistance to the carbapenem class antibiotics; this gene has not been previously assessed in iran.[objectives]detection and quantification of <italic>blaspm1</italic> metallo?lactamase gene among resistant <italic>pseudomonas aeruginosa</italic> strains (imipenem), isolated from patients in isfahan hospitals.[patients and methods]a total of 180 samples were isolated from various nosocomial infections. these isolates were identified as <italic>pseudomonas aeruginosa</italic> by using biochemical tests. in order to determine their bacterial drug resistancepattern the kirbybauer disk diffusion method was utilized. presence of mbls in imipenem isolates was detected using the combine disk technique (impedta). similarly, an etest on muellerhinton agar was used to determine the minimal inhibitory concentration (mic) of imipenem isolates. the imipenem isolates were then subjected to polymerase chain reaction (pcr) to detect the <italic>blaspm1 </italic>gene. data were analyzed using the spss software (version 16, spss inc., chicago, il, usa).[results]in total, 96 isolates of <italic>pseudomonas aeruginosa</italic> were collected. of all isolates, 34 (35.41%) were found to be imipenemresistant <italic>p. aeruginosa</italic>. the mic levels in all imipenemresistant strains were mic ? 32 ?g/ml. thirteen (38.23%) of the imipenemresistant <italic>p. aeruginosa</italic> isolates were mbl positive. none of the isolates carried the <italic>blaspm1 </italic>gene, as indicated by the pcr assay.[conclusions]the rate of imipenem resistance due to mbl has increased dramatically. early detection and infectioncontrol practices are the best antimicrobial strategy for this organism.