Journal of School of Public Health and

Background and Aim: Considering the increasing drug resistance to Aspergillus fumigatus,

search for genes involved in its pathogenicity and identifying alternative antifungal drugs is of utmost importance. The aim of this study was to determine the effects of diclofenac sodium on the growth and sidB gene expression in Aspergillus fumigatus.

Materials and Methods: In this study, Aspergillus fumigatus was cultured and a fungal suspension prepared, followed by determining the minimum inhibitory concentration of diclofenac sodium at a concentration of 25-1000 µg/ml. Then, RNA was extracted from the suspension at concentrations of 500,700 and 900 µg/ml of the drug. Finally, the extent of expression of the gene was determined by measuring different levels of mRNA-sidB by Real-time PCR.

Results: With increasing concentrations of diclofenac sodium, mycelium production decreased. Concentrations higher than 500 µg/ml had considerable inhibitory effects on the growth of Aspergillus fumigatus.

Conclusion: Findings of this study indicate that diclofenac sodium can cause a sharp reduction in the growth rate of Aspergillus fumigatus. Accordingly, it can be considered as one of the effective pharmacological agents for inhibiting the growth of this fungus.

Background and Aim: In the last few decades co-trimoxazole, an antibacterial combination of trimethoprim and sulfamethoxazole, has been used for treatment of bacterial infections, but due to the vast usage of these drugs, resistant strains have appeared throughout the world. One of the reasons for resistance to co-trimoxazole is related to drf genes, which are responsible for trimethoprim resistance, while the sulfamethoxazole resistance is due to sulfonamide sul genes. The aim of this study was to investigate drug resistance and frequencies of resistance genes in gram-negative bacteria isolated from clinical specimens.

Materials and Methods: Clinical samples were collected from patients in Pars Hospital, Tehran, Iran, in which presence of gram-negative bacteria was confirmed by biochemical tests. Then antibiotic susceptibility tests were performed for 5 antibiotics by disk diffusion agar technic. DNA was extracted from bacteria resistant to co-trimoxazole, followed by PCR using specific primers for sul1, sul2, sul3, and drf7 genes.

Results: In the co-trimoxazole-resistant bacteria, 26%, 74%, 2% and 16% of the isolates contained sul1 gene, sul2 gene, sul3 gene and drf7 gene, respectively. Further analysis of the data showed that 51% of the isolates were resistant to gentamicin, 74% to ceftriaxone, 65% to ciprofloxacin and 3% to colistin. For resistance to trimethoprim only the drf 7 gene was used.

Conclusion: The results of this study show that in the isolates of co-trimoxazole-resistant gram-negative bacteria, the sul 2 gene has a major role in development of resistance to sulfonamides. In this study only the drf 7 gene was used to assess the resistance of trimethoprim, so we recommend to conduct studies also on other drf genes, so that the importance of each in resistance to co-trimoxazole can be determined.