Detection of TEM, SHV and PER type extended-spectrum B-Lactamase genes among clinical strains of pseudomonas aemginosa isolated from burnt patients at Shafa-Hospital, Kerman, Iran

This study was carried out to evaluate the existence of the TEM, SHY and PER ESBL genes in ESBL producing strains of Pseudomonas aeruginosa isolated from burnt patients at Shafa-hospital, Kennan, Iran. A total of 120 strains of P. aeruginosa were isolated from 245 patients in burn unit of Shafa-hospital during January 2006 to December 2007. MIC of antibiotics was measured using agar dilution test ESBL producing strains were detected by double-disc synergy method containing amoxicillin and amoxicillin+clavulanic acid and phenotypic confirmatory test. All the clinical isolates resistant to imipenem [IMP] were screened for the production of MBL by E-test with IMP/IMP+EDTA strips. PCR and multiplex-PCR performed for the detection of different types of ESBL producing genes in ESBL positive isolates. Of 120 the isolates, 3-5% showed MIC greater than 16 mg/ml to IMP and meropenem, 66% showed MIC greater than 32 mg/ml to ceftazidime, 42% to azteronam and 60% of the isolates showed MIC greater than 64 mg/ml to cefotaxime, 41 [34%] contlnned as ESBL producers. Not any isolate could produce MBL [pœ0.05]. The PCR assay of all ESBL producing isolates revealed that 6.6%, 4.1% and 2.5% of them were positive for SHY, PER and TEM genes, respectively. Many ESBL producing strains of P. aeruginosa isolated from patients in burn unit of Shafa-hospital. However, none could produce MBL enzyme. The genes among ESBL producing strains were SHY, PER as well as TEM type of b-lacatamases

Plasmid mediated metal and antibiotic resistance in pseudomonas aeruginosa strains isolated from burn patients

Pseudomonas aeruginosa is a leading cause of bum infections, and antibiotic-resistant strains of this bacterium are emerging due to extensive application of antibiotics in the bum unit of hospitals. In this study 50 strains of P. aeruginosa were isolated from bum patients infected with this micro-organism in the burn unit of a general hospital in Kerman, Iran over one year [May 1999-ApriL 2000]. Sensitivity/ resistance of the isolates for antibiotics and metals was determined by MIC test. 46% of the isolates were resistant to ciprofloxacin, kanamycin [K], gentamicin [Gm], tetracycline [Te] and chloramphenicol [c]. 35% were resistant to amikacin [AN], ceftriaxone [Ceft], and cefotaxime [CTX], and 10% were resistant to imipenem [Imp] and piperacillin [PIP]. The isolates exhibited varied MIC's to metal ions. 87% were sensitive to cadmium [Cd], 62% to lead [Pb], 91% to mercury [Hg], 54% to zinc [Zn], 85% to chromium [Cr], and 83% to arsenate [Ars]. Among them, strain 16 was found to be resistant to Pb, Cr, and Zn as well as Te, C, Gm, and K. Conjugation and transformation experiments revealed the transfer of Te[r], C[r], K[r] and Gm[r] along with Pb[r] to a sensitive strain of P. aeruginosa PTCC1074.1 [Rif [r]] but not to E. coli K12 HB101.1 [Rif [r]]. Subsequent plasmid isolation and agarose gel electrophoresis [0.7%] confirmed the presence of three-plasmid bands in strain 16 and the transconjugant. Furthermore, strain 16 accumulated a maximum amount of Pb [50[micro]M] within 60 min and reached a plateau afterwards