BWH Image Archive: Rhodococcus equi

Brief synopsis: HIV+ male (CD4 count <100). Presented after 1 week history of fevers and cough. Non-compliant with anti-retrovial therapy.

Initial sputum and blood cultures grew Rhodococcus equi.

Images

Kinyoun modified acid-fast stain of non-lysed sputum, 100X.
AFB+ cocci can be seen in a macrophage.

AFB stain of Rhodococcus
Kinyoun modified acid-fast stain of non-lysed sputum, 100X.
AFB+ cocci present in field.

Chocolate agar plate of Rhodococcus
Chocolate agar plate of initial sputum culture. Arrow points to mucoid, "salmon colored" colony of R. equi.

Positive CAMP test for Rhodococcus
CAMP test for cholesterol oxidase produced by R. equi. R = Rhodococcus; S = lecithinase producing, hemolytic Staphylococcus aureus. Arrows point to additional zones of beta-hemolysis where secreted cholesterol oxidase works with lecithinase secreted by the Staphylococci to cause hemolysis of sheep's RBCs in the media.

References

Identification and mutagenesis by allelic exchange of choE, encoding a cholesterol oxidase from the intracellular pathogen Rhodococcus equi. (MEDLINE).