Investigation of Brucella agents in soil-fertilizer mixtures and animal feed samples from cattle farms after extinguished brucellosis outbreaks

Although brucellosis is under control in developed countries, it still threatens the health of animals and humans in the endemic regions. In these endemic regions although the outbreaks in some cattle farms have been officially extinguished, the farmers have wondered whether the bacteria are still present in some farm materials after extinguishment processes. The situation must be clarified so that farm production activities can continue and new animals can be procured in time. With this study, it was aimed to investigate the presence of Brucella bacteria in critical materials that may effectively transmit the disease after extinguishment procedures. For this reason, soil-fertilizer mixtures and animal feed were selected and investigated in three cattle farms where the disease was officially extinguished after the brucellosis outbreaks. The samples were collected approximately twenty days after completing extinction procedures for brucellosis. The soil-fertilizer mixtures and animal feed samples were collected in 68 and 55 pieces, respectively. The classic culture methods for the bacterial diagnosis of brucellosis were used with some modifications. After the growth of bacterial colonies on selective media, they were diagnosed by genus and species-specific PCRs. Five positive results were obtained by genus-specific PCR, but only one could be confirmed with species-specific multiplex PCR. For the remaining four, it was thought that they could belong to some soil bacteria genetically close to the Brucella genus. As a result, the brucellosis extinguishment procedures implemented could be considered adequate, and the farms were safe regarding the contamination. Although the official rules for disease extinction are fully implemented after outbreaks, similar studies are needed on more farms for more robust evaluations.