Refractory craniofacial actinomycetoma due to Streptomyces somaliensis that required salvage therapy with amikacin and imipenem

Clinical characteristics and treatment of actinomycetoma in northeast Mexico: A case series

Background

Mycetoma is a neglected tropical disease characterized by nodules, scars, abscesses, and fistulae that drain serous or purulent material containing the etiological agent. Mycetoma may be caused by true fungi (eumycetoma) or filamentous aerobic bacteria (actinomycetoma). Mycetoma is more frequent in the so-called mycetoma belt (latitude 15° south and 30° north around the Tropic of Cancer), especially in Sudan, Nigeria, Somalia, India, Mexico, and Venezuela. The introduction of new antibiotics with fewer side effects, broader susceptibility profiles, and different administration routes has made information on actinomycetoma treatment and outcomes necessary. The objective of this report was to provide an update on clinical, therapeutic, and outcome data for patients with actinomycetoma attending a reference center in northeast Mexico.

Methodology/principal findings

This was a retrospective, cross-sectional, descriptive study of 31 patients (male to female ratio 3.4:1) diagnosed with actinomycetoma by direct grain examination, histopathology, culture, or serology from January 2009 to September 2018. Most lesions were caused by Nocardia brasiliensis (83.9%) followed by Actinomadura madurae (12.9%) and Actinomadura pelletieri (3.2%). About 50% of patients had bone involvement, and the right leg was the most commonly affected region in 38.7% of cases. Farmers/agriculture workers were most commonly affected, representing 41.9% of patients. The most commonly used treatment regimen was the Welsh regimen (35.5% of cases), a combination of trimethoprim/sulfamethoxazole (TMP/SMX) plus amikacin, which had a 90% cure rate, followed by TMP/SMX plus amoxicillin/clavulanic acid in 19.4% of cases with a cure rate of 100%. In our setting, 28 (90.3%) patients were completely cured and three (9.7%) were lost to follow-up. Four patients required multiple antibiotic regimens due to recurrences and adverse effects.

Conclusions/significance

In our sample, actinomycetoma was predominantly caused by N. brasiliensis. Most cases responded well to therapy with a combination of TMP/SMX with amikacin or TMP/SMX and amoxicillin/clavulanic acid. Four patients required multiple antibiotics and intrahospital care.

Mycetoma is a chronic skin disease that can invade bone or underlying organs. Inadequate treatment may lead to long-lasting disability. Information about treatment is scarce. We report the outcomes of 31 patients with a diagnosis of bacterial actinomycetoma attending a tertiary care hospital in northeast Mexico. Most cases were treated with a combination of antibiotics including TMP/SMX plus amikacin or TMP/SMX plus amoxicillin/clavulanic acid. Cure was achieved in 90% of patients and only one required surgery.

Human cervicofacial mycetoma caused by Streptomyces griseus: First case report

Streptomyces griseus causes subcutaneous mycetomas in felines and dolphins; however, human mycetoma caused by S. griseus has not previously been reported. Hereby, we report a case of a 50-year-old female presenting with swelling in the left upper cervical region and the left cheek that lasted for 6 months. The fine needle aspiration (FNA) performed on the swelling yielded purulent material; on microscopy, actinomycosis was diagnosed. On culturing, the pus grew S. griseus. To the best of our knowledge, this is the first reported case of human mycetoma caused by S. griseus.

Efficacy of imipenem therapy for Nocardia actinomycetomas refractory to sulfonamides

BACKGROUND

Actinomycetomas are chronic, granulomatous, subcutaneous infections caused by actinomycetes bacteria. Despite prolonged high-dose and combination antibiotic therapies, some cases remain resistant with risks of bone and visceral involvement.

OBJECTIVES

We sought to evaluate the efficacy and safety of imipenem monotherapy, and in combination with amikacin for the treatment of severe and refractory disease, and to identify the disease characteristics that might predict therapy failure with first-line sulfonamides.

METHODS

A retrospective study was performed of all microbiologically confirmed cases of actinomycetomas treated since 1995 at a tertiary center for mycology. Eleven patients (Nocardia, n = 10) were treated with sulfonamide combinations (trimethoprim/sulfamethoxazole and dapsone). Eight patients (Nocardia, n = 7) refractory to previous therapies including sulfonamides received a 3-week course of either parenteral imipenem monotherapy (1.5 g daily, n = 3) or combination therapy with amikacin (1 g daily, n = 5), which was repeated at 6-month intervals.

RESULTS

Eleven patients with limited disease and mean disease duration of 1.7 years responded successfully to sulfonamides after a mean treatment period of 15 months (range 6-48 months). Patients receiving imipenem had mean disease duration of 10 years, with visceral and bone involvement in 4 patients. Imipenem treatment was well tolerated, and 4 patients achieved clinical and microbiological cure after one to two courses of treatment, the others demonstrating greater than 75% clinical improvement and negative culture results.

LIMITATIONS

Patient cohorts in this study were small because strict criteria for inclusion included species identification and adequate follow-up periods. The efficacy data for imipenem +/- amikacin therapy cannot be extrapolated to all Nocardia mycetomas, as the cohort treated in this study had particularly refractory infection.

CONCLUSIONS

Sulfonamides are effective for limited disease of relatively short duration. Imipenem monotherapy or in combination with amikacin is well tolerated and demonstrates efficacy in severe disease refractory to sulfonamides.