title: Characterisation of Pseudomonas aeruginosa related to bovine mastitis.
abstract: Pseudomonas aeruginosa is one of the causative pathogens of bovine mastitis. Most P. aeruginosa strains possess the type III secretion system (TTSS), which may increase somatic cell counts (SCCs) in milk from mastitis-affected cows. Moreover, most of P. aeruginosa cells can form biofilms, thereby reducing antibiotic efficacy. In this study, the presence and effect of TTSS-related genotypes on increase of SCCs among 122 P. aeruginosa isolates obtained from raw milk samples from mastitis-affected cows and their antibiotic susceptibility at planktonic and biofilm status were investigated. Based on the presence of TTSS-related genes a total of 82.7% of the isolates were found to harbour exoU and/or exoS genes, including the invasive (exoU-/exoS+, 69.4%), cytotoxic (exoU+/exoS-, 8.3%) and cytotoxic/invasive strains (exoU+/ exoS+, 5.0%). Milk containing exoS-positive isolates had higher SCCs than those containing exoS-negative isolates. The majority of isolates showed gentamicin, amikacin, meropenem and ciprofloxacin susceptibility at planktonic status. However, the susceptibility was decreased at the biofilm status. Based on minimum biofilm eradication concentration (MBEC)/minimum inhibitory concentration (MIC) ratios, the range of change in antibiotic susceptibility varied widely depending on the antibiotics (from ≥ 3.1-fold to ≥ 475.0-fold). In conclusion, most P. aeruginosa isolates studied here had a genotype related to increase in SCCs. The efficiency of antibiotic therapy against P. aeruginosa-related bovine mastitis could be improved by analysing both the MBEC and the MIC of isolates.
authors: Seoul National University Department of Microbiology and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine Seoul Korea.
authors: Hye Rim
authors: HR
authors: Park
authors: University of Science and Technology Viral Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology Daejeon Korea.
authors: Min Ki
authors: MK
authors: Hong
authors: Seoul National University Department of Microbiology and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine Seoul Korea.
authors: Sun Young
authors: SY
authors: Hwang
authors: Seoul National University Department of Microbiology and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine Seoul Korea.
authors: Young Kyung
authors: YK
authors: Park
authors: Seoul National University Department of Microbiology and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine Seoul Korea.
authors: Ka Hee
authors: KH
authors: Kwon
authors: Seoul National University Department of Microbiology and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine Seoul Korea.
authors: Jang Won
authors: JW
authors: Yoon
authors: Seoul National University Department of Microbiology and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine Seoul Korea.
authors: Sook
authors: S
authors: Shin
authors: Seoul National University Laboratory of Avian Disease and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine San 56-1, Daehak-dong Seoul 151-742 Korea.
authors: Jae Hong
authors: JH
authors: Kim
authors: Seoul National University Department of Microbiology and Brain Korea 21 Program for Veterinary Science, College of Veterinary Medicine Seoul Korea.
authors: Yong Ho
authors: YH
authors: Park
keywords: Pseudomonas aeruginosa; biofilm; bovine mastitis; minimum biofilm eradication concentration (MBEC); type three secretion system (TTSS)