Objective: This study aimed to investigate the antibiotic susceptibility and biofilm forming capacity of isolates of Salmonella spp., and the effect of different environmental conditions and the presence of ciprofloxacin (CIP) on biofilm forming ability.

Materials and Methods: Forty-four Salmonella spp. strains isolated in 2012 in Ege University, Faculty of Medicine, Bacteriology Laboratory of Department of Medical Microbiology, were included in this research. CIP susceptibilities were determined by microdilution method according to the CLSI recommendations and biofilm forming capacities were examined using crystal violet by spectrophotometric microplate method. Afterwards, the effects of different ambient temperatures, NaCl concentrations, pH values and presence of CIP (1/2MIC, MIC, 2MIC) on their biofilm forming capaciies were assessed. The impact of each parameter on biofilm formation in Salmonella strains with moderate and strong biofilm forming capacities at standard conditions (pH 7.3- NaCl 0.5%- 37°C) were tested singly while the other two parameters were kept at fixed levels (temperature: 4°C, 20°C, 37°C; pH: 4, 6, 7.3; NaCl: 0.5%, 4%, 6%).

Results: Under standart conditions, a total of 28 isolates of Salmonella spp. with moderate (59%) and strong biofilm (5%) forming capacities showed higher biofilm forming ability at pH 6, NaCl concentration of 6%, and ambient temperature of 20°C when compared with pH 4, NaCl concentration of 4%, and ambient temperature of 4°C. CIP resistance was found in one Salmonella spp. isolate, and one isolate demonstrated intermediate resistance to CIP. CIP inhibited both biofilm formation and showed inhibitory effect on pre-formed biofilm layer in a modarate biofilm producer.

Conclusion: This study revealed that Salmonella isolates increased their changes of staying alive in certain conditions by increasing their biofilm forming ability and CIP was found to be effective on biofilm formation.