Objectives: Drug resistance among gram-negative bacteria is a worldwide challenge. Due to the importance of drug-resistant Klebsiella pneumoniae and Escherichia coli strains in hospital-acquired infections, we aimed to determine the phenotypic and genotypic characteristics of ESBL-, AmpC-, and carbapenemase-producing isolates obtained from hospitalized patients in Tehran and Ilam (Iran). Materials and Methods: In total, 90 K. pneumoniae isolates and 65 E. coli isolates were collected from various infections. Phenotypic identification of bacterial isolates was performed using standard methods. Phenotypic screening of ESBL, AmpC, and carbapenemase enzymes was carried out. Detection of ESBL, AmpC, and carbapenemase genes was also performed by the PCR method. Results: Phenotypic detection tests showed that 36 (40%) K. pneumoniae and 23 (35.4%) E. coli isolates were ESBL producers. Moreover, 18 (20%) and 6 (9.2%) K. pneumoniae and E. coli isolates were AmpC producers, respectively. Modified Hodge test results indicated that 39 (43.3%) K. pneumoniae and 18 (27.7%) E. coli isolates produced carbapenemase. Molecular tests showed that 40% of K. pneumoniae and 36.9% of E. coli isolates were ESBL positive. AmpC was detected in 24.4 and 13.8% of K. pneumoniae and E. coli isolates. Carbapenemase was detected in 34 (37.8%) K. pneumoniae and 13 (20%) E. coli isolates. ­Conclusion: In this study, 3 K. pneumoniae isolates simultaneously carried ESBL, AmpC, and carbapenemase genes. Up-to-date strategies such as combination therapy or utilization of new antimicrobial agents might help to combat such drug-resistant organisms.

The current study aimed to investigate the prevalence of vancomycin-resistant Enterococcus in E. faecalis and E. faecium and antimicrobial susceptibility patterns, then dominant genes responsible for vancomycin resistance were determined. For this propose, 180 clinical isolates of Enterococcus were subjected for identification and antibiotic susceptibility assay. Then, the gene responsible vancomycin resistant strains were determined. The results demonstrated the E. faecalis as a dominant Enterococcus. Resistance to erythromycin was dominant and multidrug resistance strains observed in E. faecalis. vanA was responsible for vancomycin resistance. In conclusion, a high rate of resistance to antibiotics in Enterococcus is clearly problematic, and a novel strategy is needed to decrease resistance in Enterococcus.

Background: Typing of nosocomial pathogens is necessary to determine the source of an outbreak. The aim was to determine the genomic variability among Pseudomonas aeruginosa (P. aeruginosa) by random amplification of polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus (ERIC) methods. Methods: Fifty P. aeruginosa isolates were obtained from the hospitals. The source of these isolates were burn wound and urinary tract infections. After detection of P. aeruginosa by biochemical methods, chromosomal deoxyribonucleic acid (DNA) was extracted by a DNA extraction kit. ERIC-PCR and RAPD-PCR was done by standard methods. The polymerase chain reaction (PCR) products were run and visualized in 1.5% agarose gels stained with ethidium bromide. Results: Fifty P. aeruginosa isolates were analyzed by ERIC-PCR and RAPD-PCR methods. Multiple PCR fragment sizes generated by two PCR methods and PCR product size were between 200-3500 bp, and 10 and 7 different PCR patterns were detected by ERIC-PCR and RAPD-PCR, respectively. Eleven isolates were not detected by ERIC-PCR method. Fifteen isolates were typed to a single genotype by the RAPD-PCR method. Conclusions: We suggested that ERIC and RAPD PCR are equally suitable, inexpensive, fast, reproducible, and discriminatory as rapid DNA typing tools for effective epidemiological surveillance of P. aeruginosa isolates. Our results suggest that these DNA typing tools could be used in routine epidemiological surveillance, outbreak surveillance, and in the identification of the source of transmission of P. aeruginosa.