Mycobacterium Fortuitum Treatment & Management

Updated: Nov 18, 2019
  • Author: Sami M Akram, MD, MHA, RDMS; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Treatment

Medical Care

Tissue samples from biopsy, respiratory samples, or other appropriate specimens should be sent for culture and species identification. Antibiotic pattern of susceptibilities may not be sufficient to differentiate between rapidly growing mycobacterial isolates. [22] DNA sequencing (PCR) restriction endonuclease assay (PRA) may be required. In vitro susceptibility tests with MIC determination should be performed to select appropriate antibiotics. [23] Dual antibiotic therapy is recommended for treating M fortuitum infections to prevent development of resistance. No specific combination of antibiotics has been determined to be optimal. [22] M fortuitum isolates are usually susceptible to multiple oral antimicrobial agents, including the newer macrolides and quinolones, doxycycline and minocycline, and sulfonamides. Isolates are susceptible to amikacin (100%), ciprofloxacin and ofloxacin (100%), sulfonamides (100%), cefoxitin (50%), imipenem (100%), clarithromycin (80%), and doxycycline (50%). [24]

All M fortuitum isolates have been demonstrated to contain erm gene, which can be induced, causing methylation of 23sRNA and conferring macrolide resistance. [24] A 2018 study showed that the least resistance occurred with tigecycline. [25] M fortuitum is resistant to antituberculous medications. [25]

Pulmonary infections should be treated until sputum results are negative for 12 months. Treatment should be based on susceptibility results. An initial combination of amikacin and cefoxitin with or without levofloxacin is usually used for first 2-6 weeks, based on response, followed by trimethoprim-sulfamethoxazole plus doxycycline or levofloxacin to complete 6-12 months. Disseminated infections are also treated with similar parenteral followed by oral combination regimens for 4-6 months. [19]

Skin infections should be treated for at least 4-6 months with minocycline or doxycycline and either trimethoprim-sulfamethoxazole or a fluoroquinolone, based on susceptibility results. For bone infections, 6 months of therapy is recommended. [22] How much additional therapy is needed to prevent relapse is unclear.

Local wound care for cutaneous lesions is always appropriate. Small lesions may improve with local care and antibiotics without surgical intervention.

In vitro susceptibilities may not correlate with in vivo activities. Before considering major surgery, a course of at least 2 drugs may be useful, even with resistant organisms.

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Surgical Care

Consider antibiotic therapy for 2 months prior to surgery, even with resistant species. Surgery is generally indicated in cases of extensive disease, abscess formation, or unsuccessful drug therapy. Removal of foreign bodies, such as breast implants and percutaneous catheters, is important and essential to achieving cure, as M fortuitum forms biofilm.

Surgical debridement of cutaneous or subcutaneous lesions is often required to achieve cure. Surgical debridement of ocular and bone lesions is almost always required.

Surgical excision of pulmonary lesions may be considered if response to therapy is lacking or if the organism is relatively resistant to antibiotics.

Surgical excision of lymphadenitis is the therapy of choice and is usually curative.

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Consultations

Obtain consultation with an infectious disease specialist for diagnostic and therapeutic guidance.

Obtain consultation with a pulmonologist for lung lesions, for possible bronchoscopy, and for therapeutic guidance.

Obtain consultation with a surgeon for debridement and/or biopsy. Indwelling intravenous catheter placement may also be necessary if long-term antibiotics are to be administered.

Obtain consultation with a dermatologist for possible biopsy of cutaneous lesions.

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Prevention

No specific deterrence methods are available. M fortuitum is a ubiquitous organism. Avoiding exposure to tap water in the operating room and during cosmetic skin procedures helps to prevent infection. M fortuitum is resistant to chlorine disinfection. A combination of silver and copper has been shown to be more effective and holds promise as secondary disinfectants. [26]

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Long-Term Monitoring

The frequency of outpatient visits is determined by the extent of the disease and whether the patient is receiving oral or intravenous therapy. Initially, at least monthly follow-up care for adverse effects is reasonable. More frequent visits may be necessary for patients with central catheters to evaluate for line infections.

Outpatients taking aminoglycoside therapy should undergo periodic (at least weekly) assessment of renal function and antibiotic levels. Patients on aminoglycosides also need periodic audiology assessments to detect any hearing loss.

Monthly sputum cultures may be useful in patients with pulmonary disease to demonstrate the efficacy of the treatment plan.

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Further Inpatient Care

Many, if not most, patients do not require inpatient care. The duration of inpatient care is dictated by the time needed to recover from any procedures performed.

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Inpatient & Outpatient Medications

Administer antibiotics daily (see Medication).

Intermittent dosing (eg, 2-3 times/wk) has not been evaluated for M fortuitum infection and is not recommended.

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Transfer

Patients who require intravenous antibiotic therapy but who are unable to receive home intravenous therapy may need to be placed in an extended-care facility capable of administering antibiotics.

Patients with refractory disease may require a referral to a specialty center (usually as an outpatient rather than as an inpatient transfer).

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