Surgical Site Infection Owing to Mycobacterium mageritense After Immediate Breast Reconstruction Using a Deep Inferior Epigastric Perforator Flap

Summary:

Mycobacterium mageritense is a rare, rapidly growing, nontuberculosis mycobacterium that belongs to type IV of the rapidly growing mycobacteria. These bacteria are found in soil and water, and cause localized skin and soft tissue infections; however, they are challenging to culture, leading to diagnostic delays. To our knowledge, there have been 12 reported cases of surgical site infections (SSIs) caused by M. mageritense, with only 2 cases following breast reconstruction. A 51-year-old woman underwent nipple-sparing mastectomy and immediate breast reconstruction using a deep inferior epigastric perforator flap for invasive ductal carcinoma of the left breast. One month after surgery, she developed an SSI caused by M. mageritense. Despite initial outpatient treatment, the infection persisted, requiring multiple hospitalizations, administration of intravenous antibiotics, and several debridements under general anesthesia. Negative pressure wound therapy and a coordinated approach among various medical specialties are essential for managing infections. The patient experienced side effects from prolonged antibiotic use but eventually exhibited no signs of infection recurrence. This case highlights the challenges in diagnosing and treating M. mageritense SSIs, emphasizing the need for comprehensive surgical and medical management, together with patient-centered care, to effectively manage long-term treatment.

Mycobacterium mageritense (M. mageritense) is a rare type of nontuberculosis mycobacterium.¹ It is difficult to culture and sometimes requires prolonged time to reach a definitive diagnosis.² There have been 12 reported cases of SSIs caused by M. mageritense.^2–10 The characteristics of M. mageritense SSIs include an absence of pronounced inflammation, lack of established treatment methods, and prolonged treatment duration.^2,3 We present a case of SSI caused by M. mageritense that developed after breast reconstruction with a brief literature review.

CASE

A 51-year-old woman was diagnosed with invasive ductal carcinoma of the left breast. She underwent nipple-sparing mastectomy and immediate breast reconstruction using a deep inferior epigastric perforator (DIEP) flap. The patient had no medical history and was allergic to contrast agents. The navel culture results were negative before surgery. The patient showed favorable progress postoperatively and was discharged on postoperative day (POD) 11. On POD 27, a discharge of pus occurred from her navel, and she visited our hospital. The patient had no fever, and a 6-mm dehiscence was observed at the abdominal flap harvest site, with mild redness and exudate. Culture results were positive for acid-fast bacilli and M. mageritense was detected. Due to the rarity of this bacterium, prompt intervention by the infectious diseases department was requested, and daily wound irrigation initially improved the wound.

On POD 41, redness and purulent discharge were observed in the navel; however, culture results were negative. Subsequently, the redness initially improved. On POD 68, a fluctuation in the abdomen was noted, and culture results demonstrated the presence of M. mageritense. The abdominal scar and naval wound were continuous. Blood tests showed a white blood cell count of 6300 per μL and C-reactive protein level of 0.47 mg/dL, indicating a minimal inflammatory response, with mild redness around the navel. The infection worsened, necessitating hospitalization.

She was hospitalized, and antibiotics were started on POD 77. On POD 78, debridement was performed from the navel to the lower abdomen under general anesthesia. Upon making an incision from the navel to the lower abdomen, scars were observed along the suture line. Examination of excised specimens revealed multiple small abscesses within scars. The scars around the navel were larger than those around the lower abdomen. (Fig. 1) The internal infection was severe relative to the blood test results and superficial inflammatory findings. Postoperatively, the wound was cleaned daily, and once signs of infection subsided, local negative pressure wound therapy was used. The wound was closed 12 days after debridement. The patient was switched to oral antibiotics and discharged on POD 100.

Fig. 1.

Picture taken after during the first debridement. Incision was made around the navel to the lower abdomen. On the right are the multiple small abscesses within scars which were taken out.

On POD 101, purulent discharge was observed from the naval. An incision and drainage was performed, followed by daily cleansing. On POD 110, purulent discharge was observed in the left breast. Contrast-enhanced computed tomography revealed multiple abscess cavities in the abdomen and subcutaneous tissue of the breast. Despite the need for hospitalization, the patient could not be hospitalized due to busy work schedule. Therefore, the following plan was established: (1) during busy work periods, outpatient treatment with antibiotics and minor debridement was conducted and (2) if there was little improvement, hospitalization for further treatment was considered.

Consequently, the patient was readmitted on POD 126, once her work schedule permitted. Antibiotics were switched to intravenous administration, and debridement was performed under general anesthesia. On POD 128, local negative pressure wound therapy was initiated. The wound was closed on the POD 144, and the patient was switched to oral antibiotics before discharge. Follow-up was conducted at an outpatient clinic, where side effects of the antibiotics, such as anemia, visual impairment, and numbness in the lower limbs, were observed. As there was no recurrence of SSI, antibiotics were discontinued on POD 201. There was no recurrence of infection after POD 888 after breast cancer resection and reconstruction (Fig. 2).

Fig. 2.

Picture taken at POD 888. No recurrence of infection was shown even after all the antibiotics were stopped.

DISCUSSION

There have been 12 reported cases of SSIs caused by M. mageritense. (See Supplemental Digital Content 1, which describes previous reports of SSI caused by M. mageritense and sensitivity test results performed at our hospital, https://links.lww.com/PRSGO/E78.)^2–10 The characteristics include a lack of pronounced inflammatory findings, lack of established treatment methods, and long treatment durations.² For rapidly growing mycobacteria, the treatment of mild cases often involves either no treatment, careful observation, or surgical intervention. However, in severe cases, a combination of surgical treatment and antibiotic therapy is common.²

Initially, it was difficult to determine whether M. mageritense was the true causative pathogen. As the wound worsened and no other common bacteria were detected, we concluded that infection was caused by this organism.

For treatment, we referred to previous literature² and the sensitivity test results performed at our hospital (Supplemental Digital Content 1, https://links.lww.com/PRSGO/E78). The following treatment regimens were selected: imipenem 1 g twice daily (IV) + levofloxacin 500 mg once daily (IV). Considering outpatient treatment, the regimen was switched to linezolid 600 mg once daily (oral) + levofloxacin 500 mg once daily (oral). Subsequently, purulent discharge from the breast, which had not been an issue initially, was observed. However, M. mageritense was not detected in the discharge. This was interpreted not as treatment failure but as a manifestation of preexisting multiple abscesses that became apparent over time.

Although long-term outpatient treatment was initially planned, anemia and visual impairment suspected to be caused by linezolid led to its discontinuation on POD 194, and the regimen was changed to doxycycline. Later, neurological side effects were observed, and the antimicrobial therapy was completed after a total of 4 months.

M. mageritense is sometimes regarded as a contaminant but can serve as a causative pathogen in SSI. Although nontuberculous mycobacterial infections are often associated with immunocompromised individuals, M. mageritense can cause skin infections, including abscess formation, even in immunocompetent patients. Because it may form abscesses not only at the surgical site but also systemically, a comprehensive evaluation is essential when the infection is determined to be genuine.

There is no established treatment regimen for M. mageritense infections. In this case, the treatment regimen was challenging due to the limited hospitalization period and the side effects of the antibiotics. Although the therapy was completed in a relatively short period of 4 months, recurrence has not been observed (whereas other reports recommend treatment durations of 6 mo or longer). This raises the possibility that antibiotic therapy could be shortened for patients with favorable outcomes, but further research is needed to confirm this.

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this article.

PATIENT CONSENT

Written informed consent was obtained from the patient.

ETHICAL APPROVAL

Permission from the hospital’s institutional review board was not required for case reports.