Pseudomonas aeruginosa is one of the most common opportunistic microorganisms causing infections in a wide variety of patients. Increasing intrinsic and acquired resistance to antibiotics is a global challenge for the treatment of infections. The aim of this study is to evaluate the extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase activity of Pseudomonas anrogenase isolated from clinical specimens. In this research 55 strains of Pseudomonas aeruginosa isolated from clinical patients were identified by biochemical methods and then their antibiotic resistance pattern was determined by diffusion method. The strains producing ESBLs were evaluated by combined test and AmpC by the double synergism phenotypic method. Molecular methods were also used to detect strains carrying ACC, FOX, MOX, DHA, MIR, CMY, TEM, SHV and CTX genes. In this study, the highest resistance was to the antibiotic meropenem (52.7%) and the lowest resistance was to the antibiotic colistin (1.8%). When the synergism of the double discs was examined, 61.8% of the strains were found to produce AmpC. None of the strains in this study were ESBLs. The frequencies of DHA, MOX, FOX, ACC, SHV and CTX genes were 30.9%, 12.7%, 81.8%, 27.3%, 5.5% and 5.5%, respectively. MIR, CMY and TEM genes were not observed in any of the strains in this study. The results showed the frequency of the FOX gene among the strains and the greater resistance of these strains to the antibiotic meropenem, and AmpC β-lactamase activity was evaluated as an important factor in the occurrence of antibiotic resistance.

Background: Extensive use of cotrimoxazole has been associated with increasing level of Escherichia coli resistance.Objectives: In the current study, we focused on assessing the prevalence of E. coli resistance to cotrimoxazole and frequency of its associated genes.Materials and Methods: One-hundred and forty-four E. coli isolates were identified during March 2007 to April 2012 at Ilam hospitals and Milad (Tehran) hospital. Antibiotic susceptibility for screening of resistance isolates was done by the Kirby-Bauer method. The sul1, sul2, sul3, dfrA1, dfrA5, int1, blaTEM, blaSHV and CTX-M genes were detected by polymerase chain reaction (PCR) amplification. Plasmid curing was done for identifying correlations between resistance genes and plasmids.Results: Amongst the 144 E. coli isolates, seventy-two (50%) Extended Spectrum Beta Lactamase (ESBL) -producing and seventy-two (50%) non-ESBL-producing E. coli isolates were identified; eighty-seven isolates (60.41%) were resistant to cotrimoxazole. Frequencies of sul1, sul2 and sul3, were 81% (116 isolates), 67% (96 isolates) and 2.29% (three isolates), respectively. Furthermore, 50.57% (72 isolates) had sul1 and sul2, 2.29% (3 isolates) contained sul2 and sul3, and 2.29% (three isolates) contained sul1, sul2 and sul3 genes, simultaneously. Thirty-four (39.1%) of the isolates had the dfrA1 gene. Five (5.7%) of the isolates had the dfrA5 gene. Sixty-eight (78.2%) strains contained the int1 gene. Furthermore, dfrA1 and dfrA5 were present in three (3.4%) of the isolates. The results showed that of the ESBL-producing isolates, 85.2% (n=122), 53.2% (n=76) and 26.1% (n=37) were blaTEM, blaSHV and CTX-M harboring isolates, respectively.Conclusions: Our study indicated a high frequency of cotrimoxazole resistance gene in E. coli isolates from Ilam and Tehran (Milad) hospitals, and sul genes had a major role in cotrimoxazole resistance of these isolates.

Purpose: To evaluate ciprofloxacin resistance (CR) and extended-spectrum beta-lactamase (ESBL) positivity in the rectal flora, antibiotic prophylaxis received, and post-biopsy infectious complications in patients undergoing prostate biopsy. Material & Methods: Rectal swab samples collected from 99 patients suspected of prostate cancer two days before prostate biopsy were tested for microbial susceptibility and ESBL production. All patients were given standard ciprofloxacin and ornidazole prophylaxis. Ten days post-biopsy, the patients were contacted by phone and asked about the presence of fever and/or symptoms of urinary tract infection. Results: Escherichia coli (E. coli) was the most common isolate detected in 82 (75%) of the rectal swab samples. Ciprofloxacin resistance was detected in 33% and ESBL positivity in 22% of the isolated E. coli strains. No microorganisms other than E. coli were detected in blood, urine, and rectal swab cultures of patients who developed post-biopsy complications. CR E. coli strains also showed resistance to other antimicrobial agents. The lowest resistance rates were to amikacin (n = 2, 7. 4%) and nitrofurantoin (n = 1, 3. 7%). Seven patients (7. 6%) developed infectious complications. There was no significant difference in probability of hospitalization between patients with CR strains (14. 3%) and those with ciprofloxacin-susceptible strains (14. 3% vs. 4. 7%; p = 0. 194). However, strains that were both CR and ESBL-positive were associated with significantly higher probability of hospitalization compared to ciprofloxacin-susceptible strains (28. 6% vs. 3. 8%; p = 0. 009). Conclusion: The higher rate of infectious complications with CR and ESBL-positive strains suggests that the agents used for antibiotic prophylaxis should be reevaluated. It is important to consider local resistance data when using extended-spectrum agents to treat patients presenting with post-biopsy infectious complications.