Authors
Abstract
Azidiol is a chemical compound with bacteriostatic effect recommended for preserving raw milk samples, which will be used for compositional and hygienic-sanitary analyses. However, its use to preserve milk samples which will be used in the diagnosis of mastitis-causing pathogens, has not been clearly documented. The objective of this study was to evaluate the effect of azidiol on the microbiological culture detection of mastitis-causing bacteria. Milk samples, with and without azidiol, were inoculated with two bacterial concentrations from each strain included (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Escherichia coli). The results demonstrated that bacteria of Streptococcus and Staphylococcus genera, were isolated from the samples containing azidiol 24 hours after the inoculation with both bacterial concentrations, although no culture exceeded the number colony forming units inoculated at the beginning. S. agalactiae was the only bacterium that could be isolated at 48 and 72 hours of incubation of the samples inoculated with both bacterial concentrations and that contained the preservative, while E. coli was not isolated from any sample with azidiol. In the control samples (without preservative) the four strains were isolated during the three incubation times. In conclusion, the milk samples preserved with azidiol can be used on the diagnosis of mastitis-causing Gram-positive bacteria within 24 hours after the collection of milk samples, but this is not recommended neither for preserving milk samples which will be processed after this time, nor in the diagnosis of the mastitis-causing Gram-negative bacteria.
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