Case Study: Persistent infection in surgical wounds: Atypical mycobacteria and its surgical treatment

Summary

The non-tuberculous mycobacteria (NTM) have become significant opportunistic pathogens recently, and occur in epidemic proportions in some centers. For example, atypical mycobacterial infections are a frequent problem found at the port site in laparoscopic surgery patients. The NTM, which include Mycobacterium fortuitum and M. chelonae, are classified as rapid growing mycobacteria (RGM) and are grouped as M. fortuitum-chelonae complex. Non-healing postoperative wound infections that are not responsive to the types of antibiotics that are used for pyogenic infections, and have sterile routine aerobic cultures should raise a suspicion of NTM. Clinical diagnosis can be difficult, because RGM have no characteristic clinical features. There is no defined standard of antibiotics for treating RGM infections. I’ve encountered histopathology for 41 cases over 9 months of such post-operative wound infection where ultimately surgical excisions were done to get relief from the persistent and resistant infection!

Background

Atypical mycobacteria can be found in the soil, tap water, and natural water, so they can also contaminate solutions and especially disinfectants in hospital settings. This kind of infection causes significant morbidity for patients recovering from laparoscopic and other surgeries [1]. Improper sterilization of instruments is mainly responsible for such infections, and it adds to post-operative morbidity in our country and developing countries.

There is controversy about therapy for atypical mycobacteria infection. Anti-tuberculosis drugs have a limited effect on the microorganisms, so the standard treatment uses combinations of second-line anti-tuberculosis drugs, such as macrolides (e.g., clarithromycin), quinolones (ciprofloxacin), tetracyclines (doxycycline), and aminoglycosides (amikacin). When clinical symptoms are observed, the standard treatment is 28 days of oral clarithromycin and ciprofloxacin or amikacin. Local administration of aminoglycosides can also be highly effective for treating any stubborn nodules and sinuses that remain afterward [2].

But what should we do if the wound still does not heal?

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Case Presentation

  1. Surgical history: laparoscopic (11 cases) and open (5 cases) cholecystectomy, laparoscopic (3 cases) and open (2 cases) appendectomy, herniotomy (3 cases), Caesarean section (5 cases), laparoscopic ovarian cystectomy (4 cases), minor surgeries for epidermal cyst, lipoma, fistula/sinuses, breast lumps or diagnostic biopsies (8 cases).
  2. Interval after surgery: 3 to 4 weeks
  3. Age: 16 to 65 years
  4. Sex: male 12, female 29 (M:F = 1:2.4)
  5. Clinical features: a) First stage: Erythematous nodules in or around the surgical scar with mild pain and tenderness. b). Second stage: Caseating nodules with discharge of sterile pus
  6. The wounds are non-responsive to routine antibiotics and the situation worsens; discharging sinuses may develop
Figure 1: Histology of the excised wound: granulomatous inflammation with Langhans as well as foreign-body type of giant cells

Figure 1: Histology of the excised wound: granulomatous inflammation with Langhans as well as foreign-body type of giant cells

Investigations

  1. Clinical diagnosis based on the presentation
  2. NTM cultures and PCR-based assays are critical in diagnosing nontuberculous mycobacterial infection. These are time-consuming and cause a delay in therapy
  3. Cultures as well as Gram and AFB staining of specimens were all negative, so RGM infection was suspected. Sometimes aspirated material may reveal intracellular AFB. (See Figures 1 and 2.)
Figure 2: Ziehl–Neelsen-stained smear of the wound aspirate: highlights predominantly intracellular

Figure 2: Ziehl–Neelsen-stained smear of the wound aspirate: highlights predominantly intracellular

Note: Diagnosing RGM infections is difficult. High clinical suspicion should be exercised!

Differential Diagnosis

  1. Fungal abscess
  2. Mycobacterial infection
  3. Pyogenic bacterial abscess
  4. Infection with atypical mycobacteria
  5. Scar endometriosis in post-CS wounds
  6. Infected suture granulomas and other foreign-body granulomas
  7. Infections with bacteroides and other rare atypical or commensal causative organisms
  8. Malignancy

Treatment

Figure 3: Granulomatous inflammation in the case that was suspected as endometriosis in the CS scar.

Figure 3: Granulomatous inflammation in the case that was suspected as endometriosis in the CS scar.

  1. Combination antibiotic therapy (clarithromycin and ciprofloxacin, 500 mg each, twice daily for 28 days to 3 months)
  2. For resistant nodules: intra-lesion injection of Amikacin (500 mg, twice daily for five days)
  3. Drainage of surgical abscesses where productive secretions are noticed
  4. Surgical removal of the whole lesion with a few millimeters of healthy tissue with proper asepsis and precaution. This was the ultimate therapy for all cases discussed here, and no relapses occurred.

A note on prevention:

Figure 4: Small Granulomas in the infected wound, post-herniorrhaphy

Figure 4: Small Granulomas in the infected wound, post-herniorrhaphy

  1. Use good mechanical cleansing of surgical instruments to remove organic soil
  2. Exposure to 2 to 2.5% glutaraldehyde for 8-12 hours to kill endospores, and use of higher concentration (3.4%) of glutaraldehyde
  3. Use of autoclaved water to rinse off the glutaraldehyde
  4. Use of alternative systems of sterilization such as ETO gas and STERRADS, etc.
  5. Use of formalin chamber
  6. Use of disposable laparoscopic instruments

Outcome and Follow-Up

All 41 patients fully recovered from the disease, and no relapse was noted during follow-up, up to 1 year after surgery. Some patients complained of cosmetic problems and reduction in mobility.

Discussion

This is generally a localized infection, as there is little evidence of disseminated disease after these infections, except in immunocompromised hosts [3]. After the diagnosis is made, treatment can be started with a combination of second-line anti-tuberculosis drugs. Aminoglycosides have proven to be very effective in treatment of atypical mycobacterial infections of laparoscopic wounds [2-5]. Treatment in some cases has been reported to last up to six months, and sometimes, surgical excision may be necessary after the long therapy [5, 6], as it was done in the cases presented here. The surgical excision of the nasty wounds has cured the disease. Histopathological examination confirmed granulomatous inflammation with Langhans as well as foreign-body type of giant cells in most of the cases (see Figure 1). In other cases it was just an abscess wall. Occasionally, Ziehl-Neelsen-stained smears may highlight predominantly intracellular AFB [Figure 2].

Though, surgical wound debridement is generally not necessary or desired in all cases, because it also leaves a nasty wound which could risk the spread of bacteria into other areas, as mentioned by some studies. This should be used only in critical cases involving gross tissue destruction with necrosis of skin, and should not be used for every case.

Learning Points/Take Home Messages

Unresponsive nasty wound infection: suspect atypical mycobacteria.
Resistant or drug non-compliance: better go for excision.

About The Author

Dr-Swapan-Samanta-64x80
Dr. Samanta, MBBS, MD is currently a consultant at Suraksha diagnostic PVT. LTD. Kolkata, India for histopath, cytopath and hematology. His other interests are: oncopathology, bone marrow and neuropathology.

 

References (click to show/hide)

  1. Gayathri Devi DR, Sridharan D, Indumathi VA, Babu PRS, Sandhya Belwadi MR, Swamy ACV. Isolation of Mycobacterium Chelonae from wound infection following laparoscopy: a case report. Indian J Tuberc. 2004; 51:149–51.
  2. Stone HH, Kolb LD, Geheber CE, Dawkins EJ. Use of aminoglycosides in surgical infections. Ann Surg.1976; 183(6):660–66.
  3. Kalita JB, Rahman H, Baruah KC. Delayed post-operative wound infections due to non-tuberculous Mycobacterium. Indian J Med Res. 2005; 122:535–39.
  4. Muthusami JC, Vyas FL, Mukundan U, Jesudason MR, Govil S, Jesudason SR. Mycobacterium fortuitum: an iatrogenic cause of soft tissue infection in surgery. ANZ J Surg. 2004; 74(8):662–66.
  5. Rappapport W, Dunington G, Norton L, Ladin D, Peterson E, Ballard J. The surgical management of mycobacterial soft tissue infections. Surgery. 1990; 108(1):36–39.
  6. Chaudhuri S, Sarkar D, Mukerji R. Diagnosis and Management of Atypical Mycobacterial Infection after Laparoscopic Surgery. Indian J Surg 2010. 72(6):438–42.


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