The recovery of small numbers of Staphylococcus aureus infused into the bovine teat cistern

Abstract

SummarySmall volumes of milk each containing an average of less than 10 colonyforming units of Staphylococcus aureus were injected into the teat cisterns of 39 quarters of 10 cows.Typical staphylococci were recovered from only 14 quarters following overnight incubation of milk stripped manually from each quarter 10 min after injection. There was an inverse relationship between the total leucocyte count of the milk taken from the quarter before infusion and recovery of staphylococci.From 4 of 8 quarters from which Staph. aureus could not be recovered by enrichment it was possible to recover the organism by centrifuging the milk and culturing the deposit of leucocytes and bacteria.It is suggested that release of ingested staphylococci from defunct phagocytes may be important in initiation of infection, failure of antibiotic therapy and recurrence of infection.