title: Frequency of PER, VEB, SHV, TEM and CTX-M Genes in Resistant Strains of Pseudomonas aeruginosa Producing Extended Spectrum β-Lactamases.
abstract: BACKGROUND
  Pseudomonas aeruginosa is the most common pathogen causing nosocomial infections. Resistance of P. aeruginosa strains to broad-spectrum cephalosporins may be mediated by extended-spectrum β-lactamases (ESBLs).
  
  
  OBJECTIVE
  We intended to investigate the prevalence of ESBLs and antimicrobial susceptibilities of P. aeruginosa isolated from patients in Zahedan, Iran.
  
  
  METHODS
  In this cross-sectional study, during 2012-2013, 116 P. aeruginosa isolates were collected from a teaching hospital in Zahedan, Iran. Susceptibility to eight antimicrobial agents was carried out by disk diffusion method. The ESBL producing strains were detected by combination disk test (CDT). ESBL positive isolates as well as other isolates showing minimum inhibitory concentrations (MICs) ≥ 4 μg/mL for ceftazidime, cefotaxime, ceftriaxone and aztreonam, were screened for the presence of the genes encoding blaTEM, blaSHV, blaPER-1 and blaVEB-1, by polymerase chain reaction (PCR).
  
  
  RESULTS
  Ciprofloxacin and piperacillin were the most efficient antipseudomonal agents. The results disclosed that 19 (16.37%) of the isolates were multidrug resistant and 8 (6.89%) were ESBL-positive. Of the 116 isolates, 30 (25.86%) were resistant to at least one of the antibiotics ceftazidime, ceftriaxone, cefotaxime or aztreonam and among these 30 (100%), 4 (13.3%), 2 (6.6%) and 2 (6.6%), amplified blaTEM, blaVEB-1, blaPER-1 and blaSHV, respectively. From the 30 TEM-positive isolates, 22 were ESBL-negative. Sequencing of the ESBL genes verified the accuracy of the PCR products.
  
  
  CONCLUSIONS
  According to our results, blaTEM-116 was the most frequent isolated ESBL gene among the P. aeruginosa strains isolated from patients.
authors: Department of Microbiology, School of Medicine, Zahedan University of Medical Sciences, Zahedan, IR Iran ; Research Center for Infectious Diseases and Tropical Medicine, Zahedan University of Medical Sciences, Zahedan, IR Iran.
authors: Mohmmad
authors: M
authors: Bokaeian
authors: Department of Microbiology, School of Medicine, Zahedan University of Medical Sciences, Zahedan, IR Iran.
authors: Shahram
authors: S
authors: Shahraki Zahedani
authors: Department of Microbiology, School of Medicine, Zahedan University of Medical Sciences, Zahedan, IR Iran.
authors: Morteza
authors: M
authors: Soltanian Bajgiran
authors: Health Promotion Research Centre, Zahedan University of Medical Sciences, Zahedan, IR Iran.
authors: Alireza
authors: A
authors: Ansari Moghaddam
keywords: Extended-Spectrum beta-Lactamase; Pseudomonas aeruginosa