Evaluation of hematologic screening methods for early detection of Rhodococcus equi pneumonia in foals

Abstract

isolated 3 strains with different colonies sizes on the blood agar plate, UBA8Ch (0.5mm), UBA8Md (2mm) andUBA8Gd (4 mm). Expression of capsule was observed by negative staining with India ink solution and with electron microscopywith fosfotungstic acid.Diskdiffusion testwereusedas recommended by Clinical and Laboratory Standards Institute (CLSI). The antibiotic tested were: erithromycin (ERY), penicillin (PEN), ciprofloxacine (CIP), enrofloxacin (ENR), tetracycline (TET) trimethoprim-sulfamethoxazole (TMS), cefotaxime (CTX) and florfenicol (FFC). Results were categorized by using the guidelines recommended by the CLSI 2008, 2010 [3]. The capsule was observed in the 3 strains with optical microscope and with electron microscope. The strains expressed different levels of capsule, UBA8Ch: small sized, UBA8Md:medium sized andUBA8Gd: high sized. The UBA8Ch and UBA8Gd strains were susceptible for all the antimicrobials tested. The UBA8Md strain was intermedia susceptibility for ERY, ENR and TMS. The immune status of the host and the guttural pouch environment could influence in the phenotypic characteristics variation of the strains. Itwas isolated three strains froma same sample that expressed different levels of capsule, different colonies sizes on the blood agar plate and antibiotic sensibility. This suggests the presence of different clones of See in carriers.