Rhodococcus equi--an emerging human pathogen in immunocompromized hosts: a report of four cases from Malaysia.

Rhodococcus equi, a recognized pathogen in horses, is emerging as a human opportunistic pathogen, especially in immunocompromized hosts. We describe four immunocompromized patients who had serious R. equi infections with an overall mortality of 75%. The natural habitat of R. equi is soil, particularly soil contaminated with animal manure. Necrotizing pneumonia is the commonest form of infection but extrapulmonary infections, such as wound infections and subcutaneous abscess, have also been described in humans. R. equi is cultured easily in ordinary non-selective media. Large, smooth, irregular colonies appear within 48 hours. It is a facultative, intracellular, nonmotile, non-spore forming, gram-positive coccobacillus, which is weakly acid-fast staining and bears a similarity to diphtheroids. It forms a salmon-colored pigment usually after 48 hours incubation. A particular characteristic of this organism is that it undergoes synergistic hemolysis with some bacteria on sheep blood agar. R. equi may be misidentified as diphtheroids, Mycobacterium species, or Nocardia. In vitro R. equi is usually susceptible to erythromycin, ciprofloxacin, vancomycin, aminoglycosides, rifampin, imipenem and meropenem. The organism can be difficult to eradicate, making treatment challenging. Increased awareness of the infection may help with early diagnosis and timely treatment.

Salmonellosis in persons infected with human immunodeficiency virus: a report of seven cases from Malaysia.

Persons infected with human immunodeficiency virus (HIV) have an increased risk of salmonellosis when compared to the general population. We describe seven such patients with Salmonella bacteremia, of whom two had recurrent salmonellosis. In the latter two cases the infection was unusually severe, characterized by widespread infection, bacteremia and relapse, despite standard antimicrobial therapy. HIV-infected individuals will benefit from education on the source of Salmonella, mode of acquisition and prevention through safe food handling and food preparation practices. Because of the difficulty of eradicating Salmonella infection in patients with acquired immunodeficiency syndrome, long-term suppressive treatment with antimicrobials is warranted.