Cutaneous Atypical Mycobacterial Infections: A Brief Review

Abstract

Nontuberculous mycobacterial (NTM) infections are increasingly recognized, particularly in tropical regions and are often found in immunocompetent individuals. These infections are emerging as significant health concerns, especially pulmonary NTM, which is reported more frequently and is known to be associated with hospital environments. While pulmonary NTM infections are on the rise, partly due to drug resistance and possible patient-to-patient transmission, there is no current evidence indicating an increase in cutaneous NTM infections. The clinical manifestations of NTM infections, except for well-known entities like Buruli ulcer and fish tank granuloma, are diverse and nonspecific, often mimicking other chronic infections. History of minor trauma at the site of infection can be misleading and may complicate the diagnosis of cutaneous NTM. Surgical-site and port-site NTM infections typically present with erythema, edema, and abscesses and are commonly caused by rapidly growing mycobacteria like M. fortuitum and M. chelonae. These infections may not respond to standard antibiotics, suggesting the need for NTM-specific treatment. Diagnostically, histopathology may not be conclusive, and standard staining techniques often lack sensitivity. Molecular methods offer better speciation and drug resistance profiling for pulmonary NTM but are expensive and not widely available for cutaneous forms. The high cost and limited availability of diagnostic tools necessitate an empirical treatment approach, which is also recommended by the INDEX-Tb guidelines for extrapulmonary tuberculosis. Empirical treatment regimens for NTM, such as combinations of clarithromycin, doxycycline, and cotrimoxazole or fluoroquinolones, have shown promise, but there is a lack of rigorous studies to establish standardized treatments. Monitoring for adverse effects and continued evaluation of the causative organism is essential during empirical treatment, allowing for adjustment if the initial regimen fails.

Keywords: Atypical mycobacteria; NTM infections; empirical treatment; non-tuberculous mycobacterial infections; skin infections.

Figure 1

Suspected cases with cutaneous atypical mycobacterial infections. a) Multiple nodules and abscesses, with scars of healed abscesses, which started a few weeks after laparoscopic surgery. b) Nodules and abscesses forming sinuses after arthroscopic surgery through ports over the left knee, with no response to amoxicillin-clavulanic acid given for 2 weeks. c) A persisting pus-discharging sinus, appearing after the breakdown of a few pustules at the same site, after sternotomy for open heart surgery for valve repair. d) Linear scars following rupture of abscesses and healing of sinuses after initial abscess formation due to intramuscular injections for pain and multiple incision and drainage procedures for recurrent furuncles over the left buttock. e) Deep wide ulcers with pus discharge, swelling, and inflammation, which started months after intralesional steroid injections and excision for the hypertrophic scar over the hand, and did not respond to cefixime given for a week

Figure 2

Empirical treatment for post-surgical cutaneous atypical mycobacterial infection by rapid growers. a) Development of multiple abscesses which ruptured to form sinuses over port sites, 5 weeks after laparoscopic surgery. b) Good response in terms of stoppage of pus discharge and healing of sinuses after 1 month of treatment with clarithromycin 500 mg, doxycycline 100 mg, and cotrimoxazole 800/160 mg, each twice daily. There was complete healing with scarring with 3 months of therapy