First case of Serratia liquefaciens isolated from urinary tract infection in sows and associated clinicopathological and pathological findings

An incident of sudden deaths in the breeding stock was reported from a farrow‐to‐finish commercial pig farm in Greece. The 8·4% of sows during lactation and gestation period presented anorexia, fever, haematuria, return‐to‐oestrus and sudden deaths (mortality rate: 2·3%). Blood and urine samples were collected from four diseased sows. Furthermore, swabs from urine bladders were collected from two dead sows and four culled sows at the slaughterhouse. Blood testing demonstrated mild leucocytosis and absence of azotaemia. Urinalysis revealed haematuria, proteinuria, bilirubinuria and active urine sediment with bacilli, epithelial cells and leucocytes, crystals and granular casts. Histopathological evaluation of the bladder demonstrated chronic active polypoid cystitis. The bacterial culture revealed the presence of Serratia liquefaciens. The antibiotic susceptibility testing showed high resistance to the most common antibiotics, with the highest sensitivity of the isolate towards quinolones. After the administration of a single dose of 7·5 mg kg−1 body weight enrofloxacin intramuscularly, the mortality rate decreased to less than 0·5% along with a remarkable reduction in the severity of clinical signs. Based on our findings, S. liquefaciens induced severe clinical signs and deaths in sows, mainly due to urinary infection. Inadequate water sanitation might have been responsible for increased exposure to S. liquefaciens. Significance and Impact of the Study In this study, the isolation of Serratia liquefaciens from the urinary tract of pigs associated with clinical signs and increased mortality was described for the first time. Serratia liquefaciens is an important cause of hospital‐acquired human infections. The isolate in this study was resistant to the most common antibiotics. Therefore, the use of quinolones which are drugs of last resort for treatment of infections was the only therapeutic option. The presence of the resistant bacterium in the urinary tract raises concerns for its zoonotic potential. Significance and Impact of the Study: In this study, the isolation of Serratia liquefaciens from the urinary tract of pigs associated with clinical signs and increased mortality was described for the first time. Serratia liquefaciens is an important cause of hospital‐acquired human infections. The isolate in this study was resistant to the most common antibiotics. Therefore, the use of quinolones which are drugs of last resort for treatment of infections was t