Increasing awareness of Rhodococcus equi pulmonary infection in the immunocompetent adult: a rare infection with poor prognosis

N Z Med J. 2013 Dec 13;126(1387):165-74.

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.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Actinomycetales Infections* / diagnosis
  • Actinomycetales Infections* / drug therapy
  • Actinomycetales Infections* / surgery
  • Anti-Bacterial Agents / therapeutic use
  • Humans
  • Immunocompetence
  • Lung / diagnostic imaging
  • Male
  • Middle Aged
  • Pneumonia, Bacterial / diagnostic imaging
  • Pneumonia, Bacterial / microbiology*
  • Radiography
  • Respiratory Tract Infections / diagnosis
  • Respiratory Tract Infections / drug therapy
  • Respiratory Tract Infections / surgery
  • Rhodococcus equi*
  • Sex Distribution

Substances

  • Anti-Bacterial Agents