AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Advanced laboratory diagnostic techniques have improved the isolation and identification of nontuberculous mycobacteria. Mycobacterium gordonae, a commonly found species of mycobacteria, is named after its discoverer, the American bacteriologist Ruth E. Gordon. It is classified in Runyon group 2 as a scotochromogenic organism. Cultures grow slowly, are smooth, and are pigmented yellow. M gordonae is referred to as the tap water bacillus because it is a frequent isolate in tap water.

M gordonae is ubiquitous and may be found in soil, water (eg, ground, tap, bottled), whirlpools, unpasteurized milk, mucous membranes of healthy persons, urine, and gastric fluid. It is the most commonly encountered nontuberculous mycobacterium in water, with concentrations as high as 1000 colony-forming units per liter.

New cases of M gordonae disease should always be published to increase the knowledge of this disease. Many isolates represent contamination of the specimen or colonization, but not true disease. Discussing positive culture findings with microbiology laboratory personnel is useful. The authors are willing to discuss any possibly new case of M gordonae infection and are willing to offer support to write up cases of actual disease.

Pathophysiology

M gordonae is one of the least pathogenic of the mycobacteria. It is usually a contaminant or colonizer in patients who are not infected with HIV. However, in patients who are infected with HIV and have severe immunosuppression (count of <100 CD4⁺ cells/µL), M gordonae may infect the lungs, blood, bone marrow, and other organs. In the few published case reports of M gordonae disease, pathogenicity was not always established because of the presence of single isolates, the lack of confirmation by a reference laboratory, or the rapid improvement of pulmonary infiltrates, which are not characteristic features of infections from other mycobacterial species.

Frequency

United States

M gordonae disease is rare. While more than 100 cases have been reported, most documentation supports contamination or colonization rather than pathogenicity. Nosocomial pseudo-outbreaks have been described from tap water, ice machines, antimicrobial and laboratory solutions, instrumentation, fiberoptic bronchoscopes and colonoscopes (especially if the working channel is not adequately exposed to disinfectant), aerosol devices, and (possibly) continuous ambulatory peritoneal dialysis fluid.

International

Worldwide distribution is probable. Additional studies with adequate documentation are warranted to investigate the pathogenicity of M gordonae.

Mortality/Morbidity

The mortality rate is less than 0.1%. M gordonae may be a marker of severe immunosuppression in patients infected with HIV. One death was reported in a patient who was HIV positive and had severe immunosuppression, acute respiratory distress syndrome, and multiple isolates of M gordonae.

Race

No racial predilection is recognized.

Sex

No sexual predilection is known.

Age

No age predilection has been determined.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

• Fever (eg, >2 wk)

Physical

• Patients without HIV
• • Possible skin granuloma or nodule following injuries involving soil exposure (eg, gardeners)
  • Keratitis of the cornea (associated with previous trauma)
  • Lung infiltrates and/or nodules, small and thin-walled cavities in lungs
  • Possible hepatic or peritoneal infiltration or infection
  • Possible infection in urine
  • Possible prosthetic aortic valve or ventriculoatrial shunt infection
• Patients with HIV
• • Respiratory specimens with repeatedly high colony counts
  • Pulmonary infiltrates
  • Adult respiratory distress syndrome
  • Evidence of dissemination and disease (eg, cornea, peritoneal cavity, synovial fluid, urine)
  • Blood sepsis or dissemination

Causes

Positive HIV status with severe immunosuppression (<50 CD4⁺ cells/µL) is a risk factor.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Acquired immunodeficiency syndrome
Nontuberculous mycobacteria infection
Pseudo-outbreak
Colonization
Saprophyte
Contaminant

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Documentation of M gordonae disease
• Microbiologic characteristics
• • Smear-positive specimens for acid-fast bacilli
  • Isolation of organism in large numbers, quantified as growth per culture in colony-forming units (ie, >100)
  • Repeated isolation of M gordonae (ie, more than twice)
  • Detection of specific biochemical characteristics (to prove identity)
  • Consideration of confirmation from a reference laboratory
• Isolation of M gordonae from a sterile source
• Positive result from tissue culture
• Histopathologic changes characteristic of M gordonae infection
• Repeat mycobacterial cultures of sputum, blood, bone marrow, and urine (if disease is suspected)
• Blood cultures to determine presence of mycobacterial organisms

Imaging Studies

• Obtain a chest radiograph in patients with respiratory symptoms.
• Use CT scanning of the lungs, abdomen, or both to evaluate for possible dissemination.
• Consider performing abdominal ultrasonography.

Procedures

• Fiberoptic bronchoscopy helps evaluate for infiltrates.
• Consider obtaining biopsy specimens (eg, from bone marrow) to help diagnose possible dissemination.

Histologic Findings

Acid-fast stains are positive for M gordonae, and/or granulomas are present.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

Collect more data to establish the presence of disease. Clinical response to specific antimycobacterial therapy indicates possible disease presence. As with other mycobacterial organisms, slow resolution of radiographic infiltrates is expected.

• The most effective treatment regimen has not been established, but in vitro susceptibilities suggest clarithromycin and, possibly, azithromycin, quinolones (especially levofloxacin), and ethambutol as treatment options. Rifabutin may be beneficial, and rifampin shows variable results.
• The recommended duration of therapy is not established, although treating patients until culture results are documented as negative is reasonable.
• Whether additional or extended (as with tuberculosis) treatment prevents relapse remains unknown.

Consultations

• Infectious disease specialist
• Pulmonologist
• Hematologist (if bone marrow is involved)

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

While the most effective treatment regimen has not been established, in vitro susceptibilities suggest clarithromycin and, possibly, azithromycin, quinolones (eg, levofloxacin, moxifloxacin), and ethambutol as treatment options. Rifabutin may be beneficial, and rifampin has shown variable results.

In vivo activity of doxycycline and trimethoprim-sulfamethoxazole is not known.

M gordonae has been shown to be resistant to isoniazid, pyrazinamide, and streptomycin.

The recommended duration of therapy is not established.

Drug Category: Antimycobacterials

Empiric antimycobacterial therapy must be comprehensive.

Drug Name	Ethambutol (Myambutol)
Description	Standard drug for nontuberculous mycobacterial disease. Diffuses into actively growing mycobacterial cells and impairs cell metabolism by inhibiting synthesis of one or more metabolites, which, in turn, causes cell death. No cross-resistance demonstrated. Mycobacterial resistance is frequent with previous therapy. Use in these patients in combination with second-line drugs that have not previously been administered. Administer qd until permanent bacteriological conversion and maximal clinical improvement is observed. Absorption not significantly altered by food.
Adult Dose	15 mg/kg (7 mg/lb) PO qd
Pediatric Dose	<12 years: Not recommended >12 years: Administer as in adults
Contraindications	Documented hypersensitivity; optic neuritis (unless clinically indicated)
Interactions	Aluminum salts may delay and reduce absorption (administer several hours before or after ethambutol dose)
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Liver disease (only a few cases of liver toxicity have been observed); reduce dose in patients with impaired renal function; may cause adverse visual effects that may be reversible if promptly discontinued; monthly monitoring of visual acuity and color vision is recommended; approximately 1% of ophthalmologic complications occur with doses of 15 mg/kg PO qd; approximately 10% of ophthalmologic complications occur with doses of 25 mg/kg PO qd

Drug Name	Levofloxacin (Levaquin)
Description	May be useful. Aide effects are very rare (eg, GI or CNS abnormalities, tendinitis). For treatment of mycobacterial infection in combination with rifampin and other antituberculosis agents.
Adult Dose	500-1000 mg PO qd or divided bid
Pediatric Dose	<12 years: Not established >12 years: Administer as in adults
Contraindications	Documented hypersensitivity
Interactions	Antacids, iron salts, and zinc salts may reduce serum levels; administer antacids 2-4 h before or after taking fluoroquinolones; cimetidine may interfere with metabolism; reduces therapeutic effects of phenytoin; probenecid may increase serum concentrations; may increase toxicity of theophylline, caffeine, cyclosporine, and digoxin (monitor digoxin levels); may increase effects of anticoagulants (monitor PT)
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions	In prolonged therapy, periodically evaluate organ system functions (eg, renal, hepatic, hematopoietic); adjust dose in renal function impairment; superinfections may occur with prolonged or repeated antibiotic therapy

Drug Name	Rifampin (Rifadin, Rimactane)
Description	For use in combination with at least one other antituberculous drug. Inhibits DNA-dependent bacterial but not mammalian RNA polymerase. Cross-resistance may occur. Often used for nontuberculous mycobacterial disease.
Adult Dose	600 mg PO qd
Pediatric Dose	10-20 mg/kg PO; not to exceed 600 mg/d
Contraindications	Documented hypersensitivity
Interactions	Induces microsomal enzymes, which may decrease effects of acetaminophen, oral anticoagulants, barbiturates, benzodiazepines, beta-blockers, chloramphenicol, oral contraceptives, corticosteroids, mexiletine, cyclosporine, digitoxin, disopyramide, estrogens, hydantoins, methadone, clofibrate, quinidine, dapsone, tazobactam, sulfonylureas, theophyllines, tocainide, and digoxin; blood pressure may increase with coadministration of enalapril; coadministration with isoniazid may result in higher rate of hepatotoxicity than with either agent alone (discontinue one or both agents if alterations in LFT results occur)
Pregnancy	C - Fetal risk revealed in studies in animals but not established or not studies in humans; may use if benefits outweigh risk to fetus
Precautions	Obtain CBC counts and baseline clinical chemistry values prior to and throughout therapy; in liver disease, weigh benefits against risk of further liver damage; interruption of therapy and high-dose intermittent therapy are associated with thrombocytopenia that is reversible if therapy is discontinued as soon as purpura occurs; if treatment is continued or resumed after appearance of purpura, cerebral hemorrhage or death may occur

Drug Name	Rifabutin (Mycobutin)
Description	Ansamycin antibiotic derived from rifamycin S. Inhibits DNA-dependent RNA polymerase, preventing chain initiation in susceptible strains of Escherichia coli and Bacillus subtilis but not in mammalian cells. If GI upset occurs, administer dose bid with food. May be more active with nontuberculous species.
Adult Dose	300-600 mg PO qd
Pediatric Dose	Not established; 5 mg/kg/d PO suggested
Contraindications	Documented hypersensitivity; uveitis; thrombocytopenia
Interactions	Reduce to 150 mg PO qd with coadministration of protease inhibitor (eg, indinavir, nelfinavir); decreases levels of many other medications (eg, estrogens); do not exceed 300 mg qd when used with clarithromycin; steady-state zidovudine plasma levels may decrease after repeated rifabutin dosing, but this does not affect inhibition of HIV by zidovudine
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Do not administer to patients with active tuberculosis; periodically perform hematologic studies in patients receiving prophylaxis because of association with neutropenia and, more rarely, thrombocytopenia

Drug Name	Azithromycin (Zithromax)
Description	Treats mild-to-moderate microbial infections. Dosing qwk is possible.
Adult Dose	10 mg/kg PO on day 1, 5 mg/kg on days 2-5, then 10 mg/kg qwk; 1200 mg PO qwk used in adults
Pediatric Dose	10 mg/kg PO on day 1, 5 mg/kg on days 2-5, then 10 mg/kg qwk
Contraindications	Documented hypersensitivity; hepatic impairment; do not administer with pimozide
Interactions	May cause QT prolongation with cisapride, itraconazole, sparfloxacin, and other medications (probably very rare); may increase toxicity of theophylline, warfarin, and digoxin; effects are reduced with coadministration of aluminum and/or magnesium antacids; nephrotoxicity and neurotoxicity may occur when coadministered with cyclosporine
Pregnancy	B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions	Site reactions can occur with IV route; bacterial or fungal overgrowth may result with prolonged antibiotic use; may increase hepatic enzymes and cholestatic jaundice; caution in patients with impaired hepatic function or prolonged QT intervals; caution in patients who are hospitalized, geriatric, or debilitated

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• Treat until symptoms resolve. Prolonging treatment may prevent relapse, but the optimal treatment duration is unknown. Three, 6, and 12 months of therapy have been used. The improvement of objective abnormalities (eg, chest radiograph findings) may also be useful in determining the optimal duration of treatment. If the treatment time is too short, relapse may occur. If the treatment time is too long, the adverse effects of medication may become a concern.
• Isolation is not indicated (once active tuberculosis infection is excluded); however, the presence of acid-fast organisms on a stain should prompt immediate isolation unless the patient is clearly not acutely contagious.

Further Outpatient Care

• Treat in an outpatient setting. Evaluate monthly for adverse effects.

In/Out Patient Meds

• At least 2 daily drugs are indicated for documented disease. Intermittent therapy has not been evaluated.

Transfer

• Transfer to other facilities is not necessary. Consultation with an expert from the National Jewish Medical and Research Center in Denver, Colo; Centers for Disease Control and Prevention in Atlanta, Ga; local infectious disease experts; or the department of health may be useful.

Complications

• Dissemination is a concern. Death is an unlikely outcome, except in patients who are immunocompromised.
• Monotherapy may induce resistance.

Prognosis

• With treatment, the reported prognosis is excellent.

Patient Education

• Inform patients that they are not infectious and are not dangerous to other people.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• The only known medical or legal pitfall is misdiagnosing the patient with tuberculosis and any subsequent repercussions. However, if the culture report arrives after discharge, evaluate the patient for possible disease. In most cases, the isolates represent laboratory contamination of submitted specimens.

Special Concerns

• Complications during pregnancy have not been reported.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

• American Thoracic Society. Diagnosis and treatment of disease caused by nontuberculous mycobacteria. This official statement of the American Thoracic Society was approved by the Board of Directors, March 1997. Medical Section of the American Lung Association. Am J Respir Crit Care Med. Aug 1997;156(2 Pt 2):S1-25. [Medline].
• Konishi M, Uno K, Kasahara K, Mori K, Yoshimoto E, Maeda K, et al. [A case of pulmonary Mycobacterium gordonae infection progressed for no therapy]. Nihon Kokyuki Gakkai Zasshi. May 2007;45(5):436-40. [Medline].
• Lalande V, Barbut F, Varnerot A, Febvre M, Nesa D, Wadel S, et al. Pseudo-outbreak of Mycobacterium gordonae associated with water from refrigerated fountains. J Hosp Infect. May 2001;48(1):76-9. [Medline].
• Lessnau KD, Milanese S, Talavera W. Mycobacterium gordonae: a treatable disease in HIV-positive patients. Chest. Dec 1993;104(6):1779-85. [Medline].
• Sneath PH, Mair NS, Sharpe ME, eds. The Mycobacteria. Genus Mycobacterium. In: Bergey's Manual of Systematic Bacteriology. Vol 2. 2^nd ed. Baltimore, Md: Williams & Wilkins; 1986:1447.
• Weinberger M, Berg SL, Feuerstein IM, Pizzo PA, Witebsky FG. Disseminated infection with Mycobacterium gordonae: report of a case and critical review of the literature. Clin Infect Dis. Jun 1992;14(6):1229-39. [Medline].

Article Last Updated: Aug 15, 2007