Effect of Storage Temperature and Sample Volume on Brucella melitensis Isolation from Goat Milk

Aim: To determine the impact of storage temperature and sample volume on milk culture success under a simulated field setting.
Study Design: Prospective cohort study.
Place and Duration of Study: Centro de Salud Global UPCH, Tumbes, Peru and Naval Medical Research Unit SIX, Lima, Peru. April, May and June 2010.
Methodology: We aseptically collected milk from unvaccinated goats, and then experimentally inoculated the pooled milk sample with B. melintensis in order to compare the effect of two different sample volumes (2ml and 5ml) and two different storage temperatures (4ºC and -20ºC) on culture success.
Results: We achieved higher culture success in refrigerated (4ºC) versus frozen (-20ºC) samples (OR 4, 95% CI 1.7, 9.6) and with 5-ml versus 2-ml aliquots (OR 9, 95% CI 3.3, 26.6).
Conclusion: In resource-poor field settings where cold-chain and transportation are unreliable, use of ice for sample storage and transport of goat milk is an acceptable method for the purpose of culturing B. melintensis.