Non-tubercular mycobacterial infections are becoming increasingly common. Among them, the rapidly growing organisms, such as M chelonae
, M fortuitum
and M abscessus
are widespread in nature and in hospital environments. These can be isolated from water, soil and dust, and have been identified in cutaneous and joint abscesses. Infections caused by rapid-growing NTM have been reported in immunocompromised patients, frequently in renal transplant recipients1
with few reports in liver transplant recipients.2
There is no report of a surgical site infection with M abscessus
in a liver transplant recipient.
The commonest presentation of NTMs described in literature is cutaneous nodules separate from the wound sites mainly on the extremities. These infections have also been commonly described at laparoscopy port sites.3
Typically, wound infections due to NTM do not occur as an immediate postoperative complication. There is apparent immediate postoperative healing and, gradually over a variable period of time, the scar breaks down to a persistent non-healing superficial wound with discharging sinuses. This was also the presentation in our patient. These wounds are painless and patients are afebrile with no other systemic illness. Therefore, mycobacterial infection should always be ruled out in patients with chronic non-healing wounds. Investigations should include AFB smear and culture in addition to the routine gram stain and culture. These wounds do not respond to antibiotics used for the usual infections and persist for a prolonged period of time,4 5
as was observed in our patient.
Treatment of the disease depends largely on its extent and the host immune status. Surgical intervention, such as drainage of abscesses, removal of foreign bodies or wound debridement, may be required as anti-mycobacterial treatment may be less effective if dead or foreign material is present at the infection site. As the three pathogenic species of rapidly growing mycobacteria differ in antimicrobial sensitivity, susceptibility testing is recommended for successful treatment. M abscessus
has been described to infect surgical sites in non-transplant patients5
and also other organs, including lungs, prosthetic valves, lymph nodes and eyes.6
This bacterium is usually resistant to most traditional anti-mycobacterial agents. Also, M abscessus
is resistant to drugs used for NTMs, including tetracyclines, fluoroquinolones and sulphonamides. Our patient too did not respond to levofloxacin. This infection is usually sensitive to amikacin, clarithromycin and azithromycin. As clarithromycin is available in oral formulation, it is usually the first-line treatment for localised disease. Disseminated disease may require parenteral treatment with intravenous amikacin or cefoxitin, together with clarithromycin. The recommended duration of treatment is 6 months. Although our patient had localised disease, combination treatment was given in the view of her immunocompromised state. Newer drugs that have been reported to be efficacious against M abscessus
combined with clarithromycin and tigecycline.8
- Chronic non-healing surgical site infections are often misdiagnosed as bacterial or fungal infections.
- Any chronic non-healing wound should raise a suspicion of non-tuberculous mycobacteria, including a post-transplant setting.
- All chronic non-healing wounds should have acid fast bacillus smear and culture done from the wound scrapings or discharge.
- Reverse line blot hybridisation assay is useful in identifying species of non-tuberculous mycobacteria.
- Non-tuberculous mycobacteria do not respond to routine anti-mycobacterial drugs and need treatment for up to 6 months.
- M abscessus surgical site infection can occur in a liver transplant recipient.