A comparative evaluation of carried bacterial strains in sheep and goats raised in a mixed heard.

Summary Most of carried bacterial flora is found in respiratory and digestive tract of healthy animals or humans and exerts no pathogenic effect under physiolgical circumstances. When favoring factors induce immune suppression, aparently harmless strains can become highly pathogenic for animals and consumers or people who work in animal sector. The aim of the study was to identify and compare ported digestive and respiratory bacterial strains from goats and sheep cohabiting in a mixed heard. The research was carried out on 30 healthy animals (15 goats and 15 sheep) from the same heard. Nasal and rectal samples were cultured on glucose agar and on special media (McConkey, Chapman) and subsequently the isolates were identified by use of API 20 E and API 20 Staph biochemical tests. Bacterial isolates from sheep respiratory tract were Erwinia spp.(22%), Serratia liquefaciens (8%), Serratia marcescens (13%), Serratia ficaria (9%) Staphylococcus xylosus (22%), and Enterobacter cloacae (26%). The majority of bacterial isolates from goats’ respiratory tract consisted of E. coli strains (54%) while other strains were similarly represented (Serratia liquefaciens 20 %, Serratia marcescens 13%, Staphylococcus xylosus 13%). E. coli prevailed in isolates from the digestive system of both sheep (67%) and goats (62%), the rest of bacterial strains being in sheep E. vulneris (17%), Serratia marcescens (11%), and Staphylococcus xylosus (5%) and Staphylococcus xylosus (24%), E. vulneris 5% and Enterobacter cloacae (9%) in goats. Interestingly, bacteria of fecal origin such as E. coli were identified in the respiratory system of goats but not of sheep, while E. cloacae strains were represented in the respiratory tract of sheep but not of the goats. Although the flock was of mixed species, there were differences between the bacterial isolates, suggesting differentiated susceptibility and feeding behavior in these species. Nevertheless, the carried bacterial isolates from clinical healty goats and sheep could exert pathogenic effects under stressfull circumstances, underlining the importance of early identification of pathogens and the acurate sanitary management of the heard.