Aseptic technique for blood culture collection in the field to diagnose Salmonella Dublin in calves.

Abstract

Objective: To demonstrate an aseptic technique for blood culture collection on a Salmonella Dublin-suspect dairy calf in the field setting with the use of minimal restraint and basic supplies.

Animals: A neonatal Holstein heifer calf presenting with a fever of 41 °C (105 °F) and increased respiratory effort from a Salmonella Dublin-endemic dairy farm.

Methods: Appropriate supplies needed for the procedure are shown. The calf is lightly restrained by on-farm personnel, and the left side of the neck is clipped. A surgical preparation is performed. Wearing sterile gloves, the veterinarian draws blood from the left jugular vein. The top of the blood culture vial is disinfected with an alcohol wipe, and a new needle replaces the old one on the syringe. While changing the needle, the alcohol evaporates and the rubber stopper has time to dry. The blood culture media is inoculated with 2 to 3 mL of blood and inverted a few times. The blood culture vial is packaged in bubble wrap and surrounded by room-temperature ice packs for overnight delivery to a veterinary diagnostic laboratory.

Results: An aseptic blood culture sample is properly collected under field conditions without contamination of the blood culture media.

Clinical relevance: Salmonella Dublin is the host-adapted Salmonella serovar in cattle and causes high morbidity and mortality in young dairy calves. It is also multidrug resistant and zoonotic. A blood culture is currently the gold standard to diagnose Salmonella Dublin in live bovine neonates presenting with clinical signs.