Background: Brucellosis is a major cause of zoonosis disease and is endemic in hamadan Province in Iran. The purpose of this study was to isolate Brucella species from brucellosis patients and identify different species of this bacterium in order to determine the prevalence of the species.

Materials and Methods: This study was descriptive- cross sectional and fifty blood samples were obtained from brucellosis patients with clinical symptoms. The samples were cultured in BACTEC system and incubated for 14 days. Then, the samples were cultured on Brucella agar and biochemical tests were done for identification of bacteria. Finally, Polymerase Chain Reaction (PCR) applied for confirmation and isolated identification with specific primers.

Results: Seven Brucella strains were isolated from 50 blood samples of the patients with brucellosis by blood culture and PCR. The PCR results on blood specimens showed 4 positive in spite of the negative results of blood culture. PCR and biochemical methods revealed that all the 11 isolated bacteria were Brucella Melitensis.

Conclusion: This study was designed to evaluate PCR technique as a diagnostic tool for brucella spp in comparison to conventional techniques. This study showed a high prevalence of brucellosis due to Brucella Melitensis in Hamadan Province and efforts in this region should be aimed at the eradication of this bacterium.

Background: Pseudomonas aeruginosa is one of the most common nosocomial pathogens with high mortality rates. OprD is the major resistance mechanism to carbapeneme antibiotics. The aim of this study was to determine the expression of the genes encoding these efflux pumps using qRT-PCR.

Materials and Methods: This study examined 100 strains of Pseudomonas aeruginosa isolated from patients admitted to various hospitals in the Hamedan. Conventional phenotypic tests were used for identifying the 100 collected samples, then 31 samples were selected based on type of collected specimen and antibiotic susceptibility test i.e. antibiotic disk diffusion method performed for aminoglycoside, quinolone and carbapenem antibiotics. Furthermore, MIC method was performed for imipenem. Finally, RNA was extracted and converted to cDNA for determining the efflux pump genes expression using qRT-PCR.

Results: Among 8 selected antibiotics, the greatest resistance was for levofloxacin (61.2%, n=19) and the lowest one for imipenem (9.6%, n=3). The results of MIC were to imipenem 12 samples (38.7%) resistant, 13 samples (41.93%) intermediate, and 6 samples (19.35%) sensitive. The OprD gene was present in all strains but different expression has been observed. The strains with over expression of OprD gene showed high sensitivity towards carbapenems family antibiotics especially imipenem.

Conclusion: Identifying of bacterial resistance mechanisms is very complicated and extensive due to different mechanisms involved for similar antibiotics. OprD is main cause of attachment to the carbapenems family antibiotics. The more expression of OprD shows the more antibiotic sensitivity.

Background: Agr systems, is responsible for control and coordination in production of virulence factors, exotoxins secretory and hemolysins in Staphylococcus aureus. The aim of this study was to determine and identify the frequency of agr genes in susceptible and methicillin-resistant Staphylococcus aureus strains in clinical samples and carriers employed in remedial centers.

Materials and Methods: This descriptive study was done among a total of 200 strains of Staphylococcus aureus isolated from clinical samples and healthy carriers in Hamadan. Antibiotic susceptibility pattern of all isolates was determined by disk diffusion methods. After DNA extraction, the presence of mecA and agr genes was investigated using PCR. SPSS software package version 20 was used to perform statistical tests.

Results: All 200 Staphylococcus aureus strains were susceprible to vancomycin. The prevalence of mecA was 50%. The PCR results showed that agrA was the most perevalent gene followed by the agrC in all isotated Staphylococcus aureus strains. None of the isolates harbored the agrB and agrD gene.

Conclusion: Pathogenesis of Staphylococcus is dependent on some proteins other superficial or excreted which under controlling of agr system. In the present study, the feequency of agrA gene in the methicillin-resistant strains, methicillin-sensitive strains isolated from clinical samples and carriers employed in remedial centers was higher than the other agr types. Therefore, presumably, agrA gene plays an important role Staphylococcal infections.