NAME: Nocardia spp.
SYNONYM OR CROSS REFERENCE: Nocardiosis, N. cyriacigeorgica, N. farcinica, N. abscessus, N. asteroides, N. brasiliensis, N. nova, N. otitidiscaviarum, N. paucivorans, N. pseudobrasiliensis, N. transvalensis, N. veterana and N. wallacei are the most frequently reported pathogens from this genus. Rare or infrequent pathogens include: N. africana, N. anaemiae, N. araoensis, N. arthritidis, N. asiatica, N. beijingensis, N. blacklockiae, N.brevicatena, N. carnea, N. concavca, N. corynebacteroides, N. elegans, N. exalbida, N. higoensis, N. ignorata, and N. inohanensis(1) .
CHARACTERISTICS: Nocardia are actinomycetes and there are over 70 species in the genus, of which ~ 25 species are pathogenic to humans(2). They are gram positive aerobic bacteria that are 0.5-1.0 μm in diameter with branched vegetative hyphae that split into pleomorphic rods and cocci(2,3,4).
PATHOGENICITY/TOXICITY: Nocardial infections are predominantly opportunistic infections. As such, patients who are immunosuppressed (transplant patients and patients with HIV, systematic lupus erythematosis, chronic granulomatous disease, malignancies, trauma, or intravenous catheters) are at higher risk of contracting nocardiosis(2,3). Nocardial infections occur in three main forms: pulmonary, systemic, and cutaneous(3,4). Pulmonary infections usually cause acute, chronic, or relapsing bronchopneumonia that sometimes spreads to cavities and pleura(3). Symptoms include coughing, dyspnea, and fever. Pulmonary infection can lead to systemic or neurologic complications such as meningitis and brain abscesses(2,3). Nocardia brain abscesses are commonly found in the brain stem, basal ganglia, and cerebral cortex(5), and the mortality rate for patients who develop brain abscesses is about 50%(6). Systemic infections of Norcardia are rare and commonly occur in immunocompromised individuals(7). Cutaneous infection, called mycetoma, is characterized by pustules, fever, tender lymphadenitis in local lymph nodes, abscess, and yellow-white grainy discharge(3,8). Mycetoma can affect the underlying bone and is most common in adult males who walk bare foot or who have burn injuries(8). With appropriate antibiotic treatment, it is usually healed within a few weeks, though it may take up to 3 months for full clearance(8).
EPIDEMIOLOGY: Nocardia have a worldwide distribution as they are commonly present in the environment and soil; however, certain species are more common in specific geographic areas(2,3,6). N. cyriacigeorgica, N. farcinica, and N. nova are often found in non-tropical countries whereas N. brasiliensis is found in tropical and subtropical climates of America and N. otitidiscaviarum is found in the US, India, Japan, and Tunisia(2,4,6). Cases are sporadic with a majority of cases occurring in people between the ages of 21 and 50 years old, with a male/female ratio of 3:1(6).
HOST RANGE: Humans and a variety of animals (cattle, cats, dogs, chickens, ducks, fish, goats, sheep and swine) have been shown to carry the bacterium(4).
INFECTIOUS DOSE: Unknown
MODE OF TRANSMISSION: The pulmonary form is caused by inhalation of the bacteria in dust whereas the cutaneous form is caused by inoculation (for example thorn prick, cat scratch or insect bite)(2,3). Nosocomial infections have been reported(2,4).
INCUBATION PERIOD: Unknown(6)
COMMUNICABILITY: The bacterium is not transmitted from human-to-human but rather through contact with it in the environment(3).
DRUG SUSCEPTIBILITY: Most species are susceptible to trimethoprim-sulfamethoxazole, amikacin, ampicillin, carbenicillin, broad-spectrum cephalosporins, minocycline, erythromycin, ciprofloxacin, clindamycin, imipenem, and cotrimoxazol, but resistant to penicillin and antituberculous, and antifungal agents(3,4,8).
SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 2-5% phenol, 1% sodium hypochlorite, 4% formaldehyde, 2% glutaraldehyde, 70% ethanol, 70% propanol, 2% peracetic acid, 3-6% hydrogen peroxide, and iodine(9).
SURVEILLANCE: Monitor for symptoms. ELISA for detection of Nocardia -specific mAbs, PCR, sequence-based identification methods, and microscopic observation can be used to identify the presence of species in the host(2,4,11,12).
Note: All diagnostic methods are not necessarily available in all countries.
LABORATORY-ACQUIRED INFECTIONS: None reported to date
PRIMARY HAZARDS: Primary are mucocutaneous contact with the infective agent, accidental parenteral inoculation, and aerosol exposure(14).
SPECIAL HAZARDS: None
RISK GROUP CLASSIFICATION: Risk group 2(15). This risk group classification applies to the genus as a whole, and may not reflect the risk group classification of every species within the genus.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infected or potentially infected materials, animals, or cultures.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes(16).
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities(16).
SPILLS: Allow aerosols to settle, then, wearing protective clothing, gently cover the spill with absorbent paper towel and apply appropriate disinfectant, starting at the perimeter and working towards the center. Allow sufficient contact time before starting the clean up(16).
DISPOSAL: All wastes should be decontaminated before disposal either by steam sterilization, incineration or chemical disinfection(16).
STORAGE: The infectious agent should be stored in a sealed and identified container(16).
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: November 2010
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.
Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2010