Mycobacterium Abscessus Infection of a Puncture Wound of the Hand

An elderly patient with a traumatic, nonhealing wound underwent surgical debridement of the affected area. Operative cultures grew Mycobacterium species.

Case Report
A 90-year-old woman suffered a puncture wound to the dorsum on her left hand while using scissors that she owned for the past 70 years. Her primary care physician initially treated the wound with povidone-iodine soaks and Xeroform^™ gauze dressings (Tyco Healthcare/Kendall, Mansfield, Mass). Her wound failed to heal with this regimen, and she was referred for evaluation and treatment of her wound approximately 60 days post injury (Figure 1).

Her past medical history was significant for peptic ulcer disease, angina, osteoporosis, osteoarthritis, hypothyroidism, hypertension, and anemia.
On examination, this frail, elderly woman was afebrile and in no acute distress. She had no palpable lymphadenopathy and her sclera were clear. There were no intraoral lesions and her lungs were clear. Her abdomen was soft, flat, non-tender and no masses were visible or organomegaly palpable. There was no guarding, rebound or rigidity. There was a 7-mm x 5-mm open wound of the dorsum of the left hand, with induration, edema, slight erythema, and was tender to the touch. There was no increased warmth, necrosis, exudate, or maceration. Some gray discharge was evident.
The patient underwent an excisional debridement in the operating room on an elective basis. The subcutaneous tissue was noted to be brownish in color when it was debrided. A tissue sample was submitted to the North Shore-Long Island Jewish Health System Laboratories (Lake Success, NY). The sample was processed according to standard laboratory procedures for the detection of Mycobacterium spp. The tissue sample was ground, decontaminated, and digested using an N-acetyl-L-cysteine (NALC) procedure(Alpha-Tec Systems Inc,Vancouver,Wash). The processed sample was used to inoculate a MIGT tube incubated at 37^°C, Lowenstein-Jensen (LJ) agar slants (37^°C and 30^°C), and a chocolate agar slant (30^°C). Fluorochrome stained smear of the processed sample was negative. The initial cultures grew Staphylococcus aureus. Growth was detected on day 13 in the MGIT tube, and LJ media incubated at 25^°C and 30^°C. Subcultures grew within 7 days at 25^°C, 30^°C, and 37^°C. DNA probes of M tuberculosis and M avium-intracellulare complex were negative. Standard biochemical tests used to identify mycobacteria and growth on MacConkey agar suggested the organism belonged to the Mycobacterium chelonae/abscessus group. Final identification of the organism was performed at the National Jewish Medical and Research Center (Denver, Colo). The isolate was subsequently identified as Mycobacterium abscessus. The patient was admitted to the hospital and was started on cefoxitin and amikacin intravenously (IV) after a consultation with the infectious disease specialist. The isolate was eventually reported to be susceptible to amikacin, kanamycin, tobramycin, tigecycline, clarithromycin, and azithromycin, with intermediate sensitivity to imipenem, ciprofloxacin, linezolid, and resistant to cefoxitin, doxycycline, and gatifloxacin, moxifloxacin, amoxicillin/clavulanate potassium, and trimethoprim/sulfamethoxazole.
The patient received 6 days of in-patient IV antibiotic therapy with amikacin and cefoxitin. She was discharged from the hospital on clarithromycin 500 mg po BID. She was seen in the author’s office weekly and was referred to the Visiting Nurse Service of Long Island for home care. Treatment regimen consisted of washing the wound with a wound cleanser and rinsing with normal saline. SilvaSorb Gel^™ (Medline, Mundelein, Ill) was applied topically to the wound and was covered by a dry sterile dressing. Dressing changes were performed 3 times a week—Monday, Wednesday, and Friday.
The patient resided in a senior citizen complex. Several weeks after discharge, she tripped while using her walker, fell, and struck her head. She was transported via ambulance to a different hospital where she had been previously treated. A CT scan of the brain revealed an acute right subdural hematoma. The patient underwent an evacuation of the hematoma. She made an uneventful recovery, and was discharged home. During this admission, an IV was started near the infected site on her left hand.
While at home, visiting nursing service was reinstituted using the same wound care protocol. Within a week, the patient developed mental status changes and required readmission to the hospital.A CT scan revealed a left subdural hematoma. This hematoma was also evacuated. On this admission, an IV was also started in the affected hand near the wound site. The patient recovered and was again discharged to home.
During the 6 months after starting treatment on clarithromycin, and 3 times weekly dressing changes, the wound slowly improved. After the initial course of therapy, it was noted that there was persistent edema and induration around the wound. The wound closed after 180 days of therapy (Figure 2). The patient continued to complain of pain and tenderness in the area. She continued on clarithromycin because of persistent complaints of pain and physical findings of edema and mild erythema. A dressing was applied to the hand as a protectivemeasure. On 1-month follow-up the wound was found to be open. The area surrounding the wound was palpated, and a small amount of purulent material was drained. The previous wound care regimen was resumed and the wound closed again in about 2 weeks.
The patient completed a 9-month course of oral clarithromycin, after which the wound has remained closed. There was no induration, edema, tenderness, or erythema when antibiotic therapy and wound care were completed.

Discussion
Moore and Frerichs¹ recovered a rapidly growing mycobacterium (RGM) from a knee abscess in 1953 that was identified as a new species, Mycobacterium abscessus. M abscessus is an acid-fast rod classified as pathogenic nontuberculous mycobacteria, formerly classified as M chelonae subspecies abscessus. Although these organisms are ubiquitous in the environment and have been found in municipal and well water, soil, and dust, they rarely cause disease.² The species of RGM capable of producing disease in humans consist primarily of the M fortuitum group, the M chelonae/abscessus group, and the M smegmatis group.³ Human infections caused by these organisms have been reported in most areas of the world.⁴ Species of RGM have been recovered from 30% to 78% of soil samples throughout the United States.⁵ Outbreaks can involve exposure to tap water or water sources, such as ice and water-based solutions.⁶M abscessus infections have been recognized in patients with cystic fibrosis,⁷ with implantable devices,⁸ after cosmetic surgery,^9–12 after eye surgery,¹³ in hemodialysis patients,¹⁴ after cardiac surgery,¹⁵ as a cause of osteomyelitis,¹⁶ after injections,^17–19 as a cause of peritoneal catheter associated infections,²⁰ in tsunami survivors,²¹ and in animals.²² Bacteremia and disseminated infections, although rare, occur most commonly in immunocompromised hosts.^23,24

Diagnosis and Treatment
Clinical disease can be recognized when a wound fails to heal or when a previously healed wound recurs, as seen in the presented case. Frequently the disease begins as a localized abscess and cellulitis that progresses to multiple, recurrent skin abscesses and fluctuant nodules. The wounds are often tender and have mild surrounding erythema. Chronic ulcerative lesions can develop, which might have extensive subcutaneous necrosis. The extent of the necrosis is often not appreciated until the wound is debrided. The lesions can be multiple and are frequently surrounded by indurated tissue.^25,26 Diagnosis of infection relies on culture and identification of the organism. Rapidly growing mycobacterium grow in common laboratory broth (eg, tryptic soy broth) in 5–8 days without supplementation.²
Treatment involves excision, debridement, and curettage of all infected tissue, and excision of foreign bodies and infected implanted devices, as well as antimicrobial therapy.^27–29 Pneumonectomy, lobectomy, or wedge resection, may be required for pulmonary disease.³⁰
Rapidly growing mycobacterium are resistant to antituberculous agents, but are susceptible to a number of traditional antibacterial agents.²⁰ Isolates of M abscessus are susceptible to clarithromycin (100%), clofazimine (90%), amikacin (90%), cefoxitin (70%), and imipenem (50%).^31,32 No controlled clinical trials of treatment for M abscessus comparing one form of treatment with another have been performed; however, guidelines have been suggested for drug therapy on nonpulmonary disease caused by RMG.³³ The only clinical trial on M chelonae skin disease was done with clarithromycin. Of patients (all adults) treated with monotherapy at 500 mg twice a day for 6 months, all were cured except one patient who relapsed with an isolate that developed resistance to clarithromycin.³⁴ Azithromycin also appears to work well, but there is less clinical experience with this agent.² Serious, extensive, or disseminated infection requires intravenous therapy initially.¹⁸ Generally, treatment should continue for 4 to 6 months for skin, soft tissue, and bone infections.

Conclusion
Nonhealing wounds should be biopsied and cultured. Tissue should be cultured for aerobic, anaerobic, and Mycobacterium species. Prolonged treatment for Mycobacterium infection is common.

Acknowledgment 
The authors give special thanks to the Visiting Nurse Association of Long Island and to Elizabeth Brown, RN for the care of this patient. Special thanks to Nancy Caporasa of the North Shore-Long Island Jewish Health Systems Microbiology Laboratory for her assistance with organism identification and explanation of the process used in identifying the organism.