Atypical Mycobacteria Infections of Surgical Sites: A Case Series

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ATB are mycobacteria other than Mycobacterium tuberculosis and Mycobacterium leprae. They are also referred to as “nontuberculous mycobacteria” or “mycobacteria other than tuberculosis.” They comprise a group of acid-fast bacilli classified into 4 groups according to the Runyon classification: group I, photochromogens; group II, scotochromogens; group III, nonchromogens; and group IV, rapid growers.^1,2,3 Although SSIs caused by ATB are documented in abdominal surgery, their incidence following clean cases such as breast conservation surgery for early breast cancer is relatively unknown.^4,5,6

This is an observational retrospective descriptive study. Scientific and ethical clearance was granted by the Ethical Clearance Committee at M.S Ramaiah Medical College and Hospital, Bengaluru. Written informed consent was obtained from all patients included in this study.

A total of 5 female patients were included in the study. All of them presented to M.S Ramaiah Medical College and Hospital in Bengaluru, India, with clinical features suggestive of SSI that was not resolving despite standard treatment protocol. The characteristic features of each case are reported in the Table.

Discharge or wound scrapings from patients with delayed-onset SSI unresponsive to established therapeutic protocols were examined for the causative agent. ATB isolates were identified using solid and liquid culture methods. 

The cases are individually summarized below.

Case 1 

A perimenopausal, 40-year-old female with no known comorbidities presented 2 months after she underwent excisional biopsy of a right breast lump measuring 1.5 cm in a peripheral hospital. On physical examination a tender surgical scar was noted over the outer quadrant of the right breast, with overlying skin showing erythema and induration (Figure 1).

The patient underwent breast conservation surgery with a sentinel lymph node biopsy. Intraoperatively, approximately 3 mL of seropurulent fluid was noted at the previous surgical site. Three weeks later, the surgical site showed signs of inflammation with seropurulent discharge; eventually, multiple sinuses developed. 

Serial conventional culture and sensitivity tests of the pus discharge revealed no growth. Four such tests were performed. Thus, ATB infection was suspected, and the patient was started on clarithromycin and ciprofloxacin in tablet form. Over the course of treatment, there was regression of inflammation with healing of sinuses (Figure 2). A culture of curetted tissue from the sinus tracts showed the growth of Mycobacterium fortuitum. The wound healed completely in 3 months (Figure 2).

Case 2

A 26-year-old female with no known comorbid conditions presented with a gaping Pfannenstiel scar 6 months after lower segment caesarean section performed at a peripheral hospital (Figure 3). The wound did not regress despite a standard regimen of antibiotics and debridement. Multiple sinuses and indurated areas containing odorless seropurulent fluid developed at the surgical site. A trial of negative pressure wound therapy was unsuccessful.

Serial conventional wound swabs were negative for bacterial growth. Ziehl-Neelsen staining of curetted granulation tissue from the sinus tracts showed the presence of acid-fast organisms. Culture confirmed the presence of M fortuitum.

The patient was empirically started on clarithromycin and ciprofloxacin for a duration of 6 months. Gradually, over a period of 4 months, the surgical site showed complete resolution (Figure 4).

Case 3

A 45-year-old female who had previously undergone intraperitoneal onlay mesh repair for umbilical hernia and with known type II diabetes mellitus (hemoglobin A1c, 7.1%) presented with signs of mesh infection. She underwent incision and debridement with mesh explantation. Postoperatively, the patient developed multiple nodules with sinuses around the surgical site (Figure 5).

The nodules were excised and sent for culture and sensitivity testing. The report revealed the growth of M abscessus. 

The patient was treated with clarithromycin and ciprofloxacin for a period of 3 months and showed complete healing of the wound and sinuses. An incisional hernia occurred, which was repaired later.

Case 4

One month after undergoing an open appendectomy in a peripheral hospital, a 34-year-old female patient with no known comorbidities presented with signs of SSI and a sinus in the scar.

Ultrasonography of the surgical site revealed the presence of a stitch sinus. Wound exploration was undertaken. Intraoperatively, white, creamy pultaceous material was noted over the external oblique aponeurosis with intact absorbable, synthetic sutures made from polyglactin 910. This material was sent for culture and sensitivity testing, which exhibited the growth of M fortuitum. The patient was treated with clarithromycin and ciprofloxacin, and complete healing was noted after 3 months (Figure 6).

Case 5

A 32-year-old female with no known comorbidities presented with a history of open umbilical hernioplasty performed 2 months prior at a peripheral hospital. Signs of SSI were noted at the surgical scar. Minimal clear, odorless fluid was found to be exuding from the wound (Figure 7).

The patient was managed with empirical antibiotics and debridement, but there were no signs of wound healing. Results were negative for the fluid sent for Ziehl-Neelsen staining. 

Subsequently, wound scrapings were found to be positive for acid-fast bacilli. Culture and sensitivity testing revealed the presence of M chelonae.

The patient fully recuperated after receiving a combination of clarithromycin and ciprofloxacin for a period of 3 months (Figure 6).

ATB infections are an unusual cause of SSIs, affecting about 6% of surgical sites.^7,8 Such infections frequently occur in children, immunocompromised individuals, and those who have undergone implant surgeries.⁸

All 5 patients in the present series were operated on at outlying hospitals with questionable operating room sterility practices. Therefore, the nidus of infection in these illustrated cases could possibly be attributed to tainted instruments or the operating theatre milieu. 

A high grade of suspicion is vital for the diagnosis of an ATB infection. The treating surgeon should be wary of a surgical wound that heals initially but in which inflammation, serous odorless discharge, recurring sinus formation, and induration subsequently occur without systemic signs. The infection tends to track toward formerly healed scars and is classically insensitive to conventional SSI treatment regimens. Typically, sequential wound cultures are negative for bacterial growth.⁴

ATB infections occur more frequently in implant surgeries than in non-implant surgeries. A case series by Cicilioni et al illustrated 6 cases of ATB infection following prosthetic breast reconstruction.⁶ An epidemiologic review by Al-Halabi et al involving 171 patients who underwent breast implant surgery showed a 52.6% incidence of ATB infection. In the present series, 1 case (case 3) involved an implant (infected mesh), which required explantation to achieve cure.⁹

In a case series, Chaudhuri et al demonstrated 19 cases of ATB infection of port sites following laparoscopic cholecystectomy, which points toward the prominence of such infection in clean-contaminated surgeries.¹⁰

In the present series, ATB were isolated in 3 clean surgeries (3 of 5 [60%]) and 2 clean-contaminated surgeries (2 of 5 [40%]). The diagnosis can be established with negative Gram staining, positive Ziehl-Neelsen staining, and culture of discharge and tissue sample specimens. Specimens should be inoculated in liquid (BacT/Alert [Biomérieux], BACTEC [Becton Dickinson]) and/or solid media (Löwenstein-Jensen culture medium). The duration required to yield growth of the offending organism may vary from 1 week (rapid growers) to more than 3 months (slow growers). Caution must be exercised while obtaining test specimens, because environmental contamination may yield erroneous results.¹¹

In the current case series, the yield was better from tissue specimens than from simple discharge cultures. Discharge alone did not yield growth in any of the cases (0%), whereas tissue scrapings revealed ATB in 5 of 5 patients (100%). The most common organism cultured was M fortuitum (60%), followed by M abscessus (20%) and M chelonae (20%). 

Acid-fast bacilli staining of wound exudate was positive in only 1 of 5 patients (20%). This indicates the probability of misdiagnosis if only Ziehl-Neelsen stained smears are used for diagnosis.¹²

The cornerstone of treatment includes a combination of appropriate antibiotics against ATB along with minor wound debridement. First-line drugs include macrolides (eg, clarithromycin), fluoroquinolones (eg, ciprofloxacin, ofloxacin), and aminoglycosides (eg, amikacin).¹⁰ Second-line drugs include minocycline, ethambutol, rifamycin, clofazimine, and co-trimoxazole.¹³ 

Clarithromycin and ciprofloxacin are the classic first-line drugs initiated. They must be continued for a minimum of 28 days and may be needed up to 3 to 6 months, depending on the resolution of lesions.¹⁰

An adjunct modality described in the literature is the direct injection of amikacin at nodule formation or induration sites.^8,10 However, the patients in the present series achieved remission without the need for amikacin.

In the present series, treatment with clarithromycin and ciprofloxacin alone for a period of 3 to 6 months yielded a 100% cure rate (5 of 5 patients). Clarithromycin resistance must be considered in cases in which there is no response after 3 months.

No recurrence was seen after a mean follow-up period of 3 years in the patients in the present series. 

The findings of the present study are not exclusive to India and may be relevant globally. While India has a higher prevalence of ATB infections due to factors such as dense population and health care challenges, similar infections are seen in other regions, especially in parts of Southeast Asia, Africa, and even in some higher-income countries. Global travel also increases the risk of the spread of these infections. Therefore, while the data from India are vital for local health care, the issue of ATB infections is of broader concern and should be addressed globally.

This study has a few important limitations. First, the sample size is relatively small, which may not accurately reflect the disease overall. Additionally, there was limited information available about the initial presentation and the course of treatment following the primary surgery. Finally, the study includes only female patients, which may limit applicability of the results to the broader population. These issues could affect the findings and their relevance in a wider context.

ATB infections have a very low incidence following clean and clean-contaminated surgeries and are not widely documented in the literature. Diagnosis of ATB infection must be considered in patients who present approximately 1 month postoperatively with stubborn wound infection despite conventional therapy and negative sterile cultures. Management is multimodal, with antimycobacterial antibiotics and adequate surgical debridement. It is hoped that the present case series sheds light on a poorly reported but serious cause of postoperative morbidity.