title: Increasing awareness of Rhodococcus equi pulmonary infection in the immunocompetent adult: a rare infection with poor prognosis.
abstract: The aim of this case report and review is to increase awareness of this uncommon infection with Rhodococcus equi (R. equi), in immunocompetent adults. R. equi is a soil-dwelling Gram-positive bacillus that frequently causes infection in grazing livestock. Human infection is rare and mostly limited to the immunocompromised hosts. We present a case of pneumonia caused by R. equi infection in a 55-year-old male builder who presented with cough, dyspnoea and night sweats, initially suspected to have pulmonary tuberculosis. Following biopsy of the mediastinal lymph nodes, R. equi was cultured, which is usually not a contaminant. Despite extensive investigations a host immune defect was not identified. The patient recovered after three months of combination antibiotic treatment, initially with intravenous vancomycin and meropenem followed by oral clarithromycin and rifampicin. To further clarify this rare disease we did a literature review that identified 26 adult patients with R. equi infection, without an identified host immunosuppressive condition. In this cohort, the median age at presentation was 53 years and infection holds a strong male predominance 19 (73%). An environmental exposure (e.g. farming, horse breeder) was found in 13 (50%). Ten (38%) of these patients had pulmonary infection. All deaths 3 (12%) occurred in the patients had pulmonary infection. R.equi is an infection that is difficult to diagnose and carries a high mortality if prompt treatment is not established. It is important to realise the potential for this disease to be misdiagnosed as pulmonary tuberculosis or community acquired pneumonia. Clinical suspicion is important especially if an environmental exposure is suspected.
authors.affiliation: Respiratory and Interventional Pulmonology, The Montreal Chest Institute, McGill University, 3650, Rue St-Urbain, Montreal, H2X2P4, Canada. scherath@yahoo.com.
authors.forename: Samantha
authors.initials: S
authors.lastname: Herath
authors.forename: Christopher
authors.initials: C
authors.lastname: Lewis
authors.forename: Mitzi
authors.initials: M
authors.lastname: Nisbet
mesh_terms: D000193:Actinomycetales Infections / Q000175:diagnosis / Q000188:drug therapy / Q000601:surgery; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D006801:Humans; D007121:Immunocompetence; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000000981:diagnostic imaging / Q000382:microbiology*; D011859:Radiography; D012141:Respiratory Tract Infections / Q000175:diagnosis / Q000188:drug therapy / Q000601:surgery; D016929:Rhodococcus equi; D017678:Sex Distribution
chemical_list: D000900:Anti-Bacterial Agents