Nocardia

OVERVIEW

• gram positive bacilli that form weakly acid-fast beaded branching filaments
• found worldwide in soil and some form part of healthy oral flora
• usually transmitted by inhalation or traumatic inoculation
• disease of the immunocompromised – esp T-cell mediated immunity (AIDS, SCID, immunosuppressant therapy)

CLINICAL FEATURES

• pneumonia + brain abscess
• meningitis
• spinal cord
• granulomatous disease

INVESTIGATIONS

• sample graunloma
• gram stain
• culture
• BAL
• lung biopsy

MANAGEMENT

In general

• co-trimoxazole (first line agent)
• ceftriaxone (second line agent)

Brain abscess

• Expert advice recommended.
• Empiric therapy:
  trimethoprim-sulfamethoxazole 320+1600 mg (child more than 2 months: 8+40 mg/kg up to 320+1600 mg) IV or orally, 12-hourly
  PLUS EITHER
  imipenem 500 mg (child: 12.5 mg/kg up to 500 mg) IV, 6-hourly
  OR
  meropenem 2 g (child: 40 mg/kg up to 2 g) IV, 8-hourly (meropenem has a lower risk of seizures than imipenem, but there is less published data to support its use)
  OR
  amikacin (adult and child) 15 mg/kg IV, daily or amikacin (adult and child) 7.5 mg/kg IV, 12-hourly
• Subsequent therapy should be guided by species identification and susceptibility results.
  — Ceftriaxone 4 g (child: 100 mg/kg up to 4 g) IV, once daily (or in 2 divided doses) can replace the carbapenem and/or amikacin if the organism is susceptible.
  — trimethoprim-sulfamethoxazole up to 320+1600 mg (child more than 2 months: 8+40 mg/kg up to 320+1600 mg) orally, 12-hourly for up to a further 12 months.
  — amoxycillin+clavulanate, minocycline, linezolid and moxifloxacin have also been successful in small numbers of cases, particularly for some of the more unusual species.
• Duration:
  — Initial parenteral therapy should be continued for 3 to 6 weeks.
  — Oral therapy is continued for up to a further 12 months.

Prophylaxis in lung transplant patients

• low-dose trimethoprim/sulfamethoxazole prophylaxis to protect against Pneumocystis jiroveci pneumonia, toxoplasmosis and nocardial infection.

References and Links

• Brown-Elliott BA, Brown JM, Conville PS, Wallace RJ Jr. Clinical and laboratory features of the Nocardia spp. based on current molecular taxonomy. Clin Microbiol Rev. 2006 Apr;19(2):259-82. PMC1471991
• Kanne JP, Yandow DR, Mohammed TL, Meyer CA. CT findings of pulmonary nocardiosis. AJR Am J Roentgenol. 2011 Aug;197(2):W266-72. PMID: 21785052
• Leis JA, Bunce PE, Lee TC, Gold WL. Brain and lung lesions in an immunocompromised man. CMAJ. 2011 Mar 22;183(5):573-6. PMC3060186
• Saubolle MA, Sussland D. Nocardiosis: review of clinical and laboratory experience. J Clin Microbiol. 2003 Oct;41(10):4497-501. PMC254378