Atypical mycobacterial infections

Ms Montague and her colleagues (March 2003 JRSM¹) are unsure about the value of chemotherapy in atypical mycobacterial cervical adenitis. They refer to encouraging results with the macrolide clarithromycin, but both primary and secondary resistance to this agent are well recognized. There is evidence that combination therapy with rifabutin or rifampicin alongside clarithromycin has a synergistic effect, particularly against Mycobacterium avium-intracellulare complex.² This not only ensures maximum antimycobacterial activity but also may protect against the development of secondary clarithromycin resistance. Multidrug regimens employing standard antimycobacterials (isoniazid, ethambutol and/or streptomycin) used with the above combination have proven effective in cases of disseminated atypical mycobacterial infections, particularly in patients with AIDS.³ With excision biopsy early diagnosis is feasible with tools such as the polymerase-chain-reaction linked ELISA with mycobacterial DNA probes. The antimicrobial susceptibility of atypical mycobacteria can be assessed rapidly in tissue specimens by use of mycobacteria growth indicator tubes, which also give an indication of minimum inhibitory concentrations.⁴ These tools for rapid diagnosis, not yet widely available, can be helpful in decisions about postoperative chemotherapy.