Infection with nontuberculous mycobacteria is rare; however, orthopedic infections involving these species have increased since 1985.1 At least 15 different species of atypical mycobacteria have been mentioned in the literature as the cause of orthopedic infections.1Mycobacterium arupense is a recently discovered slow-growing type of non-chromogenic mycobacteria.2M arupense is closely related to the Mycobacterium terrae complex. A review of the literature found M arupense cited as the cause of a single case of tenosynovitis of the hand. To the authors’ knowledge, it has never been cited as the cause of a large joint infection.
This report describes a case of knee osteoarticular infection caused by M arupense in a 69-year-old woman with no known immunocompromising comorbidities. The patient had more than a decade of knee pain and infection refractory to multiple surgical debridements and broad-spectrum antibiotics. Radical debridement with synovectomy and large-quantity bone resection cleared the infection with greater than 2 years of follow-up.
A 69-year-old woman presented with a 3-week history of left knee pain, swelling, and inability to bear weight. She had a history of traumatic knee arthrotomy 12 years earlier that required multiple surgical debridements. The pathogenic bacteria at initial debridement were unknown. The most recent debridement was 1 year earlier for mycobacterial infection believed to be with M terrae species. On presentation to the authors’ hospital, the patient had discontinued the oral antibiotic treatment and had a recurrence of symptoms, including significant pain and swelling of the knee. Physical examination showed a small knee effusion with painful range of motion. The knee was not overtly warm or erythematous. The patient’s antibacterial regimen had been azithromycin, ethambutol, and rifampicin. Despite previous antibiotic therapy and surgical debridement, the infection persisted and the patient was presumed to have chronic nontuberculous mycobacterial osteoarticular infection.
In view of clinical evidence of infection, the patient underwent surgical debridement. Intraoperative findings of extensive soft tissue and bony infection dictated radical surgical debridement, including synovectomy with resection of the distal femur and proximal tibia. A temporary antibiotic cement spacer with tobramycin 5 g and amikacin 500 mg was placed (Figure A). The antibiotic regimen after spacer placement included azithromycin, rifampin, and ethambutol. Microbiologic findings showed acid-fast bacilli, and culture at 4 weeks grew M arupense.
Anteroposterior radiographs showing staged treatment of Mycobacterium arupense osteoarticular infection with an antibiotic spacer (A) and later tumor prosthesis (B).
The antibiotic spacer was left in place and the patient was followed closely, with no clinical signs of infection. At 4 months, the patient underwent joint aspiration and tissue cultures through an open biopsy. All findings were negative. Given the absence of infection, the patient underwent total knee arthroplasty. Because of the previous resection of the infected bone, a tumor prosthesis was necessary (Figure B). The patient continued treatment with the appropriate antibiotic regimen, according to infectious disease recommendations. At 24 months postarthroplasty, the patient had no signs of recurrence of infection and was ambulating without knee pain or the use of an assistive device.
Most attribute the increase in the incidence of musculoskeletal nontuberculous mycobacterial infections to immunosuppressive diseases.3 At least 15 species of nontuberculous mycobacteria have been mentioned in the literature as the cause of musculoskeletal infection.1 The most commonly cited nontuberculous mycobacteria species that cause osteoarticular and tenosynovial infections are Mycobacterium marinum, Mycobacterium kansasii, and the Mycobacterium avium complex.1,4,5
First isolated from clinical samples in 2006, M arupense is a slow-growing type of nonchromogenic mycobacteria.2M arupense is closely genotypically related to the M terrae complex; however, these species have different antibiotic susceptibility.2,6 Orthopedic infection caused by the M terrae complex (M terrae, Mycobacterium nonchromogenicum, and Mycobacterium triviale) and related species has been infrequently described.7–19 Most cases of orthopedic infection caused by the M terrae complex involve the tenosynovium of the hand and wrist.6,8,10–14,16,17 To the authors’ knowledge, only 3 cases of M terrae infection in large joints have been reported.7 Furthermore, only 1 report in the current literature describes an orthopedic infection caused by M arupense; this infection was a tenosynovitis of the hand.6 Review of the literature found no previous report of a large joint infection caused by M arupense.
Identification of a novel species of Mycobacterium involves gene sequencing in the microbiology laboratory. At least 30 new species of mycobacteria have been described in the past 5 years.2 Appropriate patient management depends on correct characterization and susceptibility testing of these new species. In the current case, the patient had carried a diagnosis of M terrae complex infection because the microbiology laboratory identified M arupense from intraoperative cultures. Identifying this novel species is important because the M terrae complex and M arupense have different susceptibility. Although there is no true empiric therapy for the M terrae complex, recent literature recommended clarithromycin, rifampicin, and ethambutol.7 This regimen has shown consistent inhibition of the M terrae complex. On the other hand, M arupense has been found to be resistant to rifampicin. Overall susceptibility testing of M arupense showed general susceptibility to ethambutol, clarithromycin, and rifabutin and resistance to rifampicin, linezolid, streptomycin, and the quinolones.2 In the current case, the patient had been taking a regimen that included rifampicin before the symptoms recurred and the diagnosis of M arupense infection was made.
The overall management of nontuberculous mycobacteria infection is still considered controversial. Described treatments include debridement alone, antimicrobial therapy alone with monotherapy or multiple-drug therapy, and a combination of debridement and antimicrobial treatment. The authors’ strategy, involving a combination of debridement and multiple antibiotic agents for a prolonged period, has been supported in the literature.16,17 The authors believe that the operative principles and techniques that apply to other bacterial osteoarticular infections are not adequate and should include more aggressive debridement. Additionally, this case shows the importance of correctly characterizing nontuberculous mycobacterial species to guide the selection of antibiotic agents.
- Canale ST, Beaty JH, eds. Campbell’s Operative Orthopaedics. 11th ed. Philadelphia, PA: Mosby; 2008.
- Cloud JL, Meyer JJ, Pounder JJ, et al. Mycobacterium arupense sp. nov.: a non-chromogenic bacterium isolated from clinical specimens. Int J Syst Evol Microbiol. 2006; 56:1413–1418. doi:10.1099/ijs.0.64194-0 [CrossRef]
- Kim RS, Kim JS, Choi DH, et al. M chelonae soft tissue infection spreading to osteomyelitis. Yonsei Med J. 2004; 45:169–173.
- Marchevsky AM, Damsker B, Green S, Tepper S. The clinicopathological spectrum of nontuberculous mycobacterial osteoarticular infections. J Bone Joint Surg Am. 1985; 67:925–929.
- Zenone T, Boibieux A, Tigaud S, et al. Nontuberculous mycobacterial tenosynovitis: a review. Scand J Infect Dis. 1999; 31:221–228. doi:10.1080/00365549950163482 [CrossRef]
- Tsai TF, Lai CC, Tsai IC, et al. Tenosynovitis caused by Mycobacterium arupense in a patient with diabetes mellitus. Clin Infect Dis. 2008; 47:861–863. doi:10.1086/591281 [CrossRef]
- Milne BW, Arnold MH, Hudson B, et al. Infectious arthritis of the knee caused by Mycobacterium terrae: a case report. J Orthop Surg. 2009; 17(1):103–108.
- Deenstra W. Synovial hand infection from Mycobacterium terrae. J Hand Surg Br. 1988; 13:335–336. doi:10.1016/0266-7681(88)90105-2 [CrossRef]
- Dijkmans BA, Mouton RP, Macfarlane JD, et al. Bacterial arthritis caused by Mycobacterium terrae. Infection. 1981; 9:204–207. doi:10.1007/BF01640981 [CrossRef]
- Fodero J, Chung KC, Ognenovski VM. Flexor tenosynovitis in the hand caused by Mycobacterium terrae. Ann Plast Surg. 1999; 42:330–332. doi:10.1097/00000637-199903000-00017 [CrossRef]
- Karthigasu KT, Spagnolo DV, Gow BL. Mycobacterium terrae tenosynovitis. Pathology. 1990; 22:106–107. doi:10.3109/00313029009063789 [CrossRef]
- Kremer LB, Rhame FS, House JH. Mycobacterium terrae tenosynovitis. Arthritis Rheum. 1988; 31:932–934. doi:10.1002/art.1780310721 [CrossRef]
- Love GL, Melchior E. Mycobacterium terrae tenosynovitis. J Hand Surg Am. 1985; 10:730–732. doi:10.1016/S0363-5023(85)80221-5 [CrossRef]
- May DC, Kutz JE, Howell RS, Raff MJ, Melo JC. Mycobacterium terrae tenosynovitis: chronic infection in a previously healthy individual. South Med J. 1983; 76:1445–1447. doi:10.1097/00007611-198311000-00033 [CrossRef]
- Rougraff BT, Reeck CC Jr, Slama TG. Mycobacterium terrae osteomyelitis and septic arthritis in a normal host: a case report. Clin Orthop Relat Res. 1989; 238:308–310.
- Smith DS, Lindholm-Levy P, Huitt GA, Heifets LB, Cook JL. Mycobacterium terrae: case reports, literature review, and in vitro antibiotic susceptibility testing. Clin Infect Dis. 2000; 30:444–453. doi:10.1086/313693 [CrossRef]
- Zenone T, Boibieux A, Tigaud S, et al. Non-tuberculous mycobacterial tenosynovitis: a review. Scand J Infect Dis. 1999; 31:221–228. doi:10.1080/00365549950163482 [CrossRef]
- Eskesen AN, Skramm I, Steinbakk M. Infectious tenosynovitis and osteomyelitis caused by Mycobacterium nonchromogenicum. Scand J Infect Dis. 2007; 39:179–180. doi:10.1080/00365540600798817 [CrossRef]
- Phillips MS, von Reyn CF. Nosocomial infections due to nontuberculous mycobacteria. Clin Infect Dis. 2001; 33:1363–1374. doi:10.1086/323126 [CrossRef]