Mice pathology study of toxA and exoS genes bearing Pseudomonas aeruginosa isolated from bovine Sub-clinical mastitis in West Begal with their Antibiogram

Abstract

Sub-clinical Mastitis is one of the major problems in India which is among the largest milk producing countries in the world, hampering national economy. Among 422 bovine milk samples screened from different cattle farms of West Bengal with history of infection and drop in milk yield by on-spot bromothymol blue (BTB) test, 371 samples were considered for collection and secondary screening by somatic cell count study. The collected milk samples showed significantly high average SCC value of 3.26-4.88 lakh cells/ml of milk which was indicative of infection. Samples (23, 6.53%) were found to be positive for Pseudomonas sp. showing distinct bluish-green pigmentation on cetrimide agar, typical results on morphological and in biochemical characterization. Presence of 19 (5.39%) Pseudomonas aeruginosa isolates were confirmed by fluorescent technique for detection of characteristic blue-green fluorescence by the pigment pyoverdin. PCR of these positive isolates revealed that 11 isolates were positive for toxA and 6 isolates for exoS genes with 2 isolates possessing both the genes. In Mice pathogenicity test, highest fatality (100%) was shown by the isolates with both the genes followed by isolates with toxA (66.67%) and exoS (41.67%) respectively with successful re-isolation of P. aeruginosa from the dead mice. Post-mortem examination of the dead mice showed marked haemorrhages on liver, blackish discoloration of intestines and haemorrhages on lungs. Antibiogram revealed that the isolates were highly sensitive to drugs like amikacin (89.47%), imipenem (84.21%), meropenem (78.95%) and cefoperazone-sulbactam (84.21%) but resistant to tetracycline (68.42%), piperacillin (63.16%), oxacillin (52.63%), mecilinam (47.37%) and others.

Comparative study on genotypic properties of Pseudomonas aeruginosa isolated from subclinical mastitis in Türkiye

“…While few studies have reported the isolation of P. aeruginosa from milk samples with subclinical mastitis in our country, the isolation rate has varied between 1.1% and 7.9% (Sahin and Erbas, 2015;Tel et al, 2009;Ozturk et al, 2019). In the previous studies, conducted in the world, the isolation rate has been reported as 6.5% (Banerjee et al, 2017) in India, 26.6% (Neamah et al, 2017) in Iraq, and 34% in Iran (Mokhtari et al, 2016). These differences in isolation rates may be due to regional variations and differences between isolation methods.…”

“…Neamah (2017) reported that the toxA gene was detected in 100% of strains while the exoS gene was in 75% of P. aeruginosa isolates isolated from the milk of cows with mastitis. Banerjee et al (2017) detected the toxA gene at a rate of 63.2% and the exoS gene at a rate of 36.8%. Similar to these studies (Banerjee et al, 2017;Neamah et al, 2017), many studies including virulence factors such as toxA and exoS have generally been reported at high rates and have supported the data of our study.…”

“…Banerjee et al (2017) detected the toxA gene at a rate of 63.2% and the exoS gene at a rate of 36.8%. Similar to these studies (Banerjee et al, 2017;Neamah et al, 2017), many studies including virulence factors such as toxA and exoS have generally been reported at high rates and have supported the data of our study.…”

“…To our knowledge, P. aeruginosa isolated from mastitis in dairy cattle has not been reported as imipenem resistant in Türkiye. However, there are very few studies examining integron (Mokhtari et al, 2016) or virulence genes carried by the bacteria (Banerjee et al, 2017;Neamah et al, 2017). P. aeruginosa with many virulence factors affects the outcome of infections.…”