Isolation Pseudomonas aeruginosa bacteria and genes integron class I of subclinical mastitis in dairy cows in Tehran

Pseudomonas aeruginosa is an important opportunistic pathogen that causes subclinical mastitis resistant to treatment, in lactating dairy cows. The Purpose of this study, were to identify class I integrons and determining antibiotic susceptibility of Pseudomonas aeruginosa isolated from mastitis. In this cross-sectional study, 150 samples of raw milk were collected from different farms, transported to the laboratory and cultured on specific media. Antimicrobial susceptibility test conducted by disk diffusion method and MIC (Minimum Inhibitory Concentration) determination test performed by E-test in accordance with CLSI guidelines, in various groups. To identify Class I integron gene PCR test were used. Of total number 150 milk samples, 51 samples (34%) were contaminated with Pseudomonas aeruginosa. Antibiotic test results showed that the highest rate of resistance were observed to Ampicillin, Tetracycline and Kanamycin at the rate of 100%, 94.2% and 94.2%, respectively. Most multiple resistances were observed against Kanamycin, Ampicillin and Tetracycline antibiotics. MIC results showed that isolated bacteria were sensitive to Gentamicin in concentration 0.75-2 μg, Ciprofloxacin at 0.094-0.38 μg and Amikacin at 0.05-4 μg. Results molecular tset showed, one isolate (1.96%) were carried Integrons gene (int-1). Since most integrons genes coding enzymes that inactive antibiotics, presence of Integrons genes in samples of raw milk, treatment infections caused by Pseudomonas aeruginosa wich carring these genes, because of the lack of new antibiotics that have a broad therapeutic range, would creat the major problems.