Serratia liquefaciens mastitis in a dairy herd

Abstract

Serratia liquefaciens mastitis was detected and investigated in a 41-cow Holstein herd.Twenty cows were treated for mastitis over a 3-month period.Serratia liquefaciens was isolated from milk samples obtained from 8 of 12 cows tested during the epizootic.Results of an epidemiologic investigation suggested that extensive frostbite of the teats decreased the udder defense.Poor milking technique and hygiene were responsible for increased exposure of the dam aged teats to potential udder pathogens.Treatment of each cow resulted in initial clinical improvement, but exacerbations occurred in 75% of the cows with documented S liquefaciens infections.Serratia spp are gram-negative motile bacilli of the family Enterobacteriaceae, tribe Klebsielleae.Commonly found in soil and water, they were consid ered nonpathogenic saprophytic bacteria.More re cently, antibiotic-resistant Serratia spp have been associated with nosocomial infections in both human and veterinary hospitals.1"4Serratia marcescens and Serratia liquefaciens have been incriminated as causes of mastitis in dairy cows.5-9Serratia marcescens mastitis has been associ ated with contaminated water.Howell reported that most S marcescens infected quarters responded to treatment with broad-spectrum antibiotics, but some were refractory.7 Australian investigators found S liquefaciens in the milk of 5 cows with clinical mastitis in a 120-cow herd.By inoculating clinically normal udder quarters of cows with a suspension of S liquefaciens organisms, these investigators were able to induce mild clinical mastitis.5During December 1983, veterinary service was requested for a 3-year-old first-lactation cow with acute mastitis.Abnormal physical findings included rectal temperature of 39.7 C and moderate edema of one udder quarter.Milk from the affected quarter was of normal color, but was slightly watery, with occasional clots.Serratia liquefaciens was isolated from the milk.No previous Serratia mastitis in fections had been identified in this herd.The cow responded favorably to intramammary infusion of gentamicin sulfate and iv administration of chloram phenicol.The mastitic cow belonged to a 41-cow Holstein dairy herd managed as part of a family farm.The