P019

M. abscessus spp. are known for their potential to cause agressive skin and tissue infections, often posing a diagnostic challenge, as underscored by following case.

A 47-year-old male farmer presented with a progressive painful swelling of the arm that started 6 months earlier after a banal injury between the first and second finger of the right hand.

Initially, antibiotic therapy under the form of clindamycin and amoxicillin / clavulanic acid was started, but failed to improve symptoms. A tentative diagnosis of reactive tenosynovitis was made, but NSAID’s and cortisone infiltrations only temporarily relieved symptoms.

Despite consulting multiple physicians from various disciplines, no conclusive diagnosis could be made. Eventually, a tissue biopsy was performed and cultured, which unexpectedly yielded mycobacterial colonies which were  identified as M. abscessus. Unfortunately, the significance of this result was initially misclassified as irrelevant contamination, further delaying appropriate treatment.

Finally, another consulted clinician correctly recognised M. abscessus as the causative pathogen, and adequate treatment consisting of amikacin, azithromycin, clofazimine and linezolid was initiated. In the reference lab, the NTM was subtyped as  M. abscessus subspecies abscessus, with the antibiogram showing no need to change the antibiotic combination. The patients symptoms steadily improved, and therapy was maintained during 9 months.

NTM skin infections still remain underdiagnosed and due to their atypical presentation, they can pose significant challenges in diagnosis and management, particularly in individuals with compromised immune systems or predisposing skin conditions.