Prevalence of ESBLs genes among multidrug-resistant isolates of Pseudomonas aeruginosa isolated from patients in Tehran.
Drug susceptibility testing and PCR assay were used to determine the antibiotic susceptibility patterns and prevalence of genes encoding five different extended spectrum betalactamases (ESBLs) (PER, VEB, SHV, GES, and TEM) among 600 isolates of Pseudomonas aeruginosa cultured from patients at two hospitals in Tehran. Susceptibility of isolates to 12 different antibiotics was tested using disk diffusion method. The MICs for ceftazidime and imipenem were also determined using microbroth dilution assay. Isolates showing MICs >or=16 for ceftazidime were subjected to PCR targeting bla(SHV), bla(PER), bla(GES), bla(VEB), and bla(TEM) genes that encode ESBL. The rates of resistance were as follows: tetracycline (92%), carbenicillin (62%), cefotaxime (56%), ceftriaxon (53%), piperacilin (46%), gentamicin (31%), piperacilin/tazobactam (28%), ceftazidime (25%), amikacin (23%), ciprofloxacin (19.5%), and imipenem (6%). Thirty-nine percent of isolates (n = 234) showed MICs >or=16 microg/ml for ceftazidime, and 5.45% showed MICs >or=16 microg/ml for imepenem. The imipenem-resistant isolates showed high rate of susceptibility to colistin (89%) and polymixin B (95.5%). The frequency of bla(VEB), bla(SHV), bla(PER), bla(GES), and bla(TEM) among the ESBL isolates (MIC >or=16) were 24%, 22%, 17%, 0%, and 9%, respectively. Isolates containing bla(VEB) were resistant to almost all tested antibiotics except imepenem. This is the first report on the existence of bla(VEB), and bla(PER) in Iran. Colistin and polymixin B are highly potent against the imipenem-resistant isolates of P. aeruginosa.
Shahcheraghi
Freshteh
F
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran. shahcheraghi@pasteur.ac.ir
Nikbin
Vajiheh-Sadat
VS
Feizabadi
Mohammad Mehdi
MM
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D006761:Hospitals; D006801:Humans; D007492:Iran; D008826:Microbial Sensitivity Tests; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics*; D047090:beta-Lactams / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D017931:DNA Primers; D004269:DNA, Bacterial; D047090:beta-Lactams; D001618:beta-Lactamases