Clinical case of isolation and identification of <I>Streptococcus equi subsp. Zooepidemicus</I>

Abstract

Streptococci manifest their pathogenic properties by reducing the overall resistance of the organism or individual tissues.Purpose of the work: isolation, identification and study of the biological properties of isolates isolated from the foal.A pure culture was obtained, morphological, cultural and biochemical properties were studied.For the subsequent identification of streptococci to species, two api 20 Strep test systems (BIOMERIEUX, France) were used. To determine the serological group of streptococci, a latex agglutination test was used using a kit for diagnosing streptococci of groups A, B, C, D, F, and G (OXOID, UK).Laboratory methods of diagnostics for the identification of causative agents of streptococcosis and their species differentiation have been studied. Virulent Streptococcus equi subsp. zooepidemicus caused abscesses in the area of the elbow joint of the foal. Isolation of bacterial cultures was carried out by the bacteriological method. Isolated Streptococcus equi subsp. zooepidemicus had the fermentation of a number of carbohydrates: sorbitol, there was no splitting of lactose, tregolose. Streptococcus equi subsp. zooepidemicus hydrolyzed esculin, no D-ribose fermentation was noted. However, the fermentation of carbohydrates is not a stable and clear sign, therefore it is not used for differentiation and identification of streptococci.When inoculated on blood agar with 5% sheep blood after cultivation for 24 hours at 37 0C, small gray-white colonies were found, surrounded by a wide transparent zone of beta-hemolysis. Catalase test is negative.As a result, it was found that the isolated culture belongs to the species Streptococcus equi subsp. zooepidemicus belonging to group C according to Lancefield.Modern laboratory diagnostics requires an integrated approach to identification, which includes bacteriological and serological methods - polyphase analysis. When identifying streptococci, the determination of their serological group according to Lancefield is of great importance. For this purpose, a latex agglutination reaction is convenient using a kit for diagnosing streptococci of groups A, B, C, D, F and G (OXOID, UK), coagglutination "Streptotest A, B, C, D, G" (AQUAPAST).