Rhodococcus equi Pneumonia in a Patient with Human Immunodeficiency Virus
Rhodococcus equi Pneumonia in a Patient with Human Immunodeficiency Virus
Rhodococcus equi is a facultative, intracellular, gram-positive coccobacillus increasingly reported as an opportunistic pathogen in patients positive for human immunodeficiency virus (HIV). An HIV-positive man developed R. equi pneumonia and sepsis. He failed to improve despite surgical drainage of localized infection and many empiric antibiotics. Time-kill studies of R. equi isolated from the patient were performed against various antimicrobial agents to optimize therapy. Levofloxacin seemed to offer excellent in vitro bactericidal activity. Antagonism was observed with certain antibiotic combinations. Our anecdotal case report suggests that fluoroquinolones such as levofloxacin may offer superior efficacy to standard therapy in rhodococcal infections; their clinical utility deserves further investigation. In view of potential antagonism, prospective susceptibility testing for various drugs and drug combinations should be considered when clinically indicated.
Rhodococcus equi (previously known as Corynebacterium equi), a soil saprophyte and gram-positive, pleomorphic coccobacillus, is well known to veterinary microbiologists because it causes suppurative bronchopneumonia in foals and other animals. It also can cause invasive cavitary pneumonia as an opportunistic pathogen in immunocompromised patients. Tissue Gram's stain may reveal clusters of gram-positive cocci and rods within the spindle cells. This finding suggests the existence of longstanding infection. Rhodococcus species, which may be acid fast, can be distinguished from mycobacterial species by the 14-day arylsulfatase test, as Rhodococcus is negative for this reaction.
Rhodococcus equi is a facultative, intracellular, gram-positive coccobacillus increasingly reported as an opportunistic pathogen in patients positive for human immunodeficiency virus (HIV). An HIV-positive man developed R. equi pneumonia and sepsis. He failed to improve despite surgical drainage of localized infection and many empiric antibiotics. Time-kill studies of R. equi isolated from the patient were performed against various antimicrobial agents to optimize therapy. Levofloxacin seemed to offer excellent in vitro bactericidal activity. Antagonism was observed with certain antibiotic combinations. Our anecdotal case report suggests that fluoroquinolones such as levofloxacin may offer superior efficacy to standard therapy in rhodococcal infections; their clinical utility deserves further investigation. In view of potential antagonism, prospective susceptibility testing for various drugs and drug combinations should be considered when clinically indicated.
Rhodococcus equi (previously known as Corynebacterium equi), a soil saprophyte and gram-positive, pleomorphic coccobacillus, is well known to veterinary microbiologists because it causes suppurative bronchopneumonia in foals and other animals. It also can cause invasive cavitary pneumonia as an opportunistic pathogen in immunocompromised patients. Tissue Gram's stain may reveal clusters of gram-positive cocci and rods within the spindle cells. This finding suggests the existence of longstanding infection. Rhodococcus species, which may be acid fast, can be distinguished from mycobacterial species by the 14-day arylsulfatase test, as Rhodococcus is negative for this reaction.
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