Internal Medicine

0521779407-15 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:43

Nocardiosis 1051

NOCARDIOSIS

RICHARD A. JACOBS, MD, PhD

history & physical

History

■Nocardiaare aerobic, Gram-positive, branching filamentous organ-

isms that appear beaded on Gram stain and are acid-fast.

■They are ubiquitous in nature, found in soil and organic matter.

■N. asteroidesis most common species causing human infection;

other human pathogens includeN. brasiliensis, N. farcinica, N. nova,

N. transvalensis, N. otitidiscaviarum.

■Transmission to humans is by inhalation or direct inoculation into

skin; human-to-human transmission does not occur.

■Risk factors include immunosuppression (organ transplantation),

corticosteroids, chronic lung disease (especially alveolar prote-

inosis) and diabetes; one third have no predisposing conditions.

Signs & Symptoms

■Pulmonary infection presents as cough, fever, weight loss, malaise

and can be insidious or acute.

■Cutaneous disease results from direct inoculation and presents as

mycetoma (usually tropical areas), chronic nodular lymphangitis

with nodular lesions following the distribution of lymphatics (usu-

allyN. brasilinsis) or as cellulitis indistinguishable from other bac-

terial causes of cellulitis; cutaneous involvement resulting from

hematogenous dissemination manifests as multiple, diffuse subcu-

taneous nodules that may be tender

■CNS disease presents insidiously with headache, nausea, vomiting,

visual changes or focal neurologic findings resulting from abscess

formation; meningitis occurs less frequently and usually presents

subacutely with headache

tests

■Routine laboratory tests rarely helpful in making diagnosis; blood

cultures almost always negative; in meningitis, CSF may be culture

positive with hypoglycorrhachia and a neutrophilic pleocytosis

■Chest x-ray nonspecific-consolidation, nodules with or without cav-

itation, reticulonodular pattern and effusion all described

■CT or MRI of brain may reveal abscess