Successful treatment of cutaneous Mycobacterium chelonae infection with roxithromycin

Abstract

Dear Editor, Mycobacterium chelonae is a rapidly growing mycobacterium that causes illnesses ranging from disseminated cutaneous infection, localized cellulitis, abscess, osteomyelitis, to catheter infection in immunocompetent or immunosuppressed patients. 1 Recent studies have shown that isolates of M. chelonae are usually susceptible to clarithromycin, 1,2 and thus it has been the drug of choice for cutaneous M. chelonae infection. 3 However, there have been case reports of clarithromycin resistance in patients with M. chelonae infection. [4][5][6][7] We report a case of cutaneous M. chelonae infection which exhibited resistance to clarithromycin and was successfully treated with roxithromycin.A 36-year-old, previously healthy, Japanese woman presented in April 2006 with a 4-week history of a painful subcutaneous nodule on the right upper arm. She had no previous history of trauma. Physical examination revealed a firm subcutaneous nodule 3 cm in diameter on the outside of her right upper arm. There was no discoloration of the overlying skin. Magnetic resonance imaging (MRI) of the nodule demonstrated a subcutaneous mass with similar signal intensity to muscle on T1-weighted images (Fig. 1), and a high signal on T2-weighted images. Postcontrast T1-weighted images demonstrated intense enhancement of the subcutaneous nodule, suggesting a hypervascular tumor. A presumptive clinical diagnosis of a subcutaneous tumor such as angioleiomyoma was made, and the tumor was excised. Histological examination of the tumor revealed a dense infiltrate of neutrophils, monocytes and lymphocytes ( Fig. 2a). A few granulomas with multinuclear giant cells were also seen ( Fig. 2b). A diagnosis of an abscess with an infectious granuloma was suggested, but Ziehl-Neelsen, Gram, and periodic acid-Schiff staining did not reveal any microorganisms. Two months later, a subcutaneous nodule recurred beside the excision site. A biopsy specimen of the nodule revealed the same histological findings. A culture of the nodule revealed a rapidly-growing Mycobacterium, which was identified as M. chelonae by DNA-DNA hybridization. Susceptibility testing of the organism was not performed. Oral minocycline, 100 mg twice daily, was started and subsequently discontinued due to gastrointestinal symptoms. After identification of the organism, she was treated with oral clarithromycin, 200 mg twice daily, for 5 weeks but the subcutaneous nodule enlarged. The treatment was changed to oral roxithromycin, 150 mg twice daily, which resolved the nodule within the first 4 weeks. Figure 1. Transverse magnetic resonance imaging (MRI) of the nodule on the right upper arm. T1-weighted imaging demonstrates a mass with similar signal intensity to muscle in the subcutaneous fat (arrow).

Mycobacterium chelonae Is an Ubiquitous Atypical Mycobacterium

“…Obtaining in vitro susceptibilities is essential in directing treatment [ 8 ], but since it usually takes some time to obtain the antibiogram, suggested initial regimens include clarithromycin with the addition of imipenem, tobramycin or amikacin [ 12 , 14 ]. Many other newer antibiotics were successful in treating M. chelonae infections, like faropenem [ 13 ] and roxithromycin [ 15 ], and other treatment modalities should be considered in more recalcitrant or small lesions, such as surgical excision or cryotherapy [ 10 ].…”

The fish tank strikes again: Metachronous nontuberculous mycobacterial skin infection in an immunosuppressed host

“…Table 1 outlines the recommended treatment for selected cutaneous NTM infections. 4,9,[11][12][13][14] Treatment guidelines need refinement, however clarithromycin is recommended as a first-line therapy. 15 To avoid acquired resistance a second agent should be added based on sensitivity testing, particularly for M. chelonae, although tolerability and multi-resistant organisms are limiting factors and further antibiotic development is needed.…”

“…A repeat biopsy is advised if treatment failure or relapse is suspected. Clarithromycin, minocycline, doxycycline, co-trimoxazole or combination of rifampicin and ethambutol for 3-6 months 9,13,14 Clarithromycin for 3-6 months (azithromycin or roxithromycin may also be considered); with addition of second antibiotic based on results of sensitivity testing to prevent acquired resistance 9,[11][12]…”

Cutaneous Mycobacterium chelonae infection successfully treated with faropenem

“…In our case, the dose might have been insufficient, but the drug was thought to be ineffective because the eruption showed no changes after clarithromycin administration for 4 weeks. There are several similar reports in which initial clarithromycin treatment had no effect, 7 and an in vitro study showed that only 49% of M. chelonae clinical isolates are susceptible to this agent 8 . Thus, clarithromycin may not be a universal treatment for M. chelonae infection.…”