Generally, actinomycetoma is amenable to medical treatment with antibiotics and other chemotherapeutic agents. Combined drug therapy is always preferred to a single drug to avoid drug resistance and for disease eradication. Cure is possible, although a prolonged period of treatment is needed.
In the past, the treatment of actinomycetoma was by combination of streptomycin sulfate 14 mg/kg daily for 1 month, then on alternate days, and 4,4´-diaminodiphenyl sulfone (dapsone) 1.5 mg/kg twice daily until cure. The cure rate varied between 60 and 90%. This treatment regime needs a long duration to achieve cure and has many side effects.
For patients who do not respond to treatment or those who had persistent side effects to dapsone, the dapsone is replaced by co-tri-moxazole 1.5 mg/kg twice daily. Certain actinomycetes, such as Actinomadura pelletierii, had good response to this combination, and it was used as the first-line treatment.
Many other drugs, such as rifampin, sulfadoxine and pyrimeth-amine (Fansidar ®), and sulfonomides, had been tried as a second line of treatment for actinomycetoma for patients who did not respond to the first-line treatment or who developed serious drug side effects. However, these drugs take a long time to achieve cure, the mean duration was approximately one year and the recurrence rate was high. They have many side effects, and some of these were serious, such as Stevens–Johnson syndrome.
Currently, many reports showed excellent clinical response to the combination of amikacin sulfate and co-tri-moxazole, the Welsh regimen. They were given in a form of cycles; each one consisted of amikacin sulfate 15 mg/kg twice daily for three weeks and co-tri-moxazole in a dose of 1.5 mg/kg twice daily for 5 weeks and the cycles were repeated until cure.
The number of cycles ranged between five and ten cycles. Renal failure and ototoxicity are well-recognized complications, and resistant cases to this regimen have been recently reported.
Presently, a good number of antibiotics and antimicrobials drugs were tested for the treatment of actinomycetoma either in clinical trials or in experimental animal models either as monotherapy and in different combination. That includes gentamicin and kanamycin, sulfonamides, netilmicin, linezolid, amoxicillin–clavulanic acid, ciprofloxacin, moxifloxacin, meropenem, and few others. The results of these studies were not remarkable, some drugs showed several side effects and somewhere not cost effective.
The actinomycetoma causative bacteria rapidly become resistant to various antibiotics and antimicrobials; therefore, it is necessary to regularly test the sensitivity of the available drugs, both in vitro and in vivo, and clinicians should be on the lookout for novel treatments.
Whichever regimen is used, regular and close follow-up of patients, along with renal, hepatic and hematological assessments and evidence of ototoxicity, are mandatory.
In actinomycetoma, combined medical and surgical treatments are beneficial. This regime facilitates surgery, accelerates healing and reduces the chance of relapse; however, a good number of patients respond to medical treatment alone.
Recurrence is more common after an incomplete or irregular course of medical treatment. With drug incompliance, there is a good chance for the organism to develop drug resistance.
Medical treatment for both types of mycetoma must continue until the patient is clinically, radiologically, ultrasonically and cytologically cured. Cure is considered when the skin becomes normal, the mass disappears, the sinuses heal and the organisms are eliminated from the tissue. Clinical improvement is judged by reduction in the size of the mass and healing of most of the sinuses.
Radiological examination is an essential tool for follow up of patients on medical treatment. It usually shows reappearance of normal bone pattern and the disappearance of the soft-tissue mass. Absent grains cytologically with type III tissue reaction and the disappearance of the grains and cavities ultrasonically are reliable evidences for cure.