Relationship between Biofilm Formation and Antibiotic Resistance and Adherence Genes in Strains Isolated from Raw Cow Milk in Shahrekord, Iran.

The production of biofilms by contributes significantly to treatment failures. The present study aims to establish the relationship between biofilm formation and antibiotic resistance and adhesion genes in strains isolated from raw cow milk in Shahrekord, Iran. A total of 90 samples of raw cow's milk were collected. Presumptive strains were obtained using Baird-Parker plates after enrichment in tryptone soy broth, and final colonies were selected from brain heart infusion. Additional tests such as coagulase were done, and the identification was confirmed by the detection of the gene. Biofilm producing strains were screened using a spectrophotometry method applied to microplates. Crystal violet staining was used to quantify the formation of biofilm. An antibiotic susceptibility test was performed using the Kirby-Bauer disc diffusion method. PCR was used to detect several biofilm and antibiotics resistance related genes. The chi-square test and Fisher's exact test were used to establish a statistically significant relationship between biofilm reaction and antibiotic resistance ( value <0.05). Results show a moderate (38.88%) recovery rate of in milk and 65.71% of the isolates were strong biofilm producers. Antibiotic susceptibility tests show an alarming rate of resistance to beta-lactam antibiotics, especially penicillin (100%), ampicillin (91.42%), and oxacillin (71.42%). This finding correlates with antibiotic resistance gene detection, in which the gene was most found (71.42%), followed by and (42.85%). Detection of biofilm-related genes shows that all the genes targeted were found among isolates. Statistical tests show a significant correlation between biofilm production and antibiotic resistance in . This study revealed that there is a significant correlation between biofilm production and antibiotic resistance in isolated from raw milk. These results highlight the need for regular surveillance of the occurrence of strains in milk and milk products in Iran.