Mycobacteroides abscessus: Identification and Treatment Challenges

J Clin Aesthet Dermatol. 2025;18(1–2 Suppl 1):S12–S14.

by Blair Ferguson, APRN, DNP

Mr. Ferguson is with Natura Dermatology and Cosmetics in Fort Lauderdale, Florida.

Funding: No funding was provided for this article.

Disclosures: The author reports no conflicts of interest relevant to the content of this article.

ABSTRACT: Cutaneous mycobacterial infections present an ongoing challenge in terms of diagnosis and treatment options. Accurate diagnosis of cutaneous mycobacterial infections can take eight weeks, and they often provide few medication options. Increasing antibiotic resistance limits treatment options, especially by mouth. Negative diagnostic tests such as biopsies, serology, and cultures in the presence of a cutaneous mycobacterial infection are common and could prolong the diagnosis. This report highlights key features, including the atypical appearance of discharge, the eruption of an adjacent abscess with potential sinus tract formation, and lack of pain in discomfort that is often seen in cellulitis. The purpose of this case report is to discuss the lengthy process from suspected diagnosis to treatment, as well unanticipated challenges such as laboratory errors, to assist clinicians in prompt decision making.

KEYWORDS: Cutaneous mycobacterial infections, mycobacterium abscessus, mycobacteroides abscessus

Introduction

Cutaneous mycobacterial infections are relatively common, with a three-fold increase from 1980 to 2009,¹ and are associated with a number of difficulties. Mycobacterial infections can mimic other dermatological conditions and might not present as a typical cellulitis case, which can delay diagnosis. Mycobacterial infections are selectively responsive to a more narrow range of antibiotics, and a culture might be necessary to identify the most appropriate medication.² Mycobacterial cultures, whether it be from a fresh tissue specimen or a swab, are test specific² and might produce a negative result if a standard aerobic and anaerobic culture and sensitivity is ordered. Therefore, the provider must suspect a mycobacterial infection first, so that the appropriate test can be ordered; otherwise, diagnosis and treatment might be delayed. Mycobacterial infections further present with an additional complication; current laboratory timeframes for cultures take two months.³ Unfortunately, oral therapies are limited, and many antibiotics are intramuscular or intravenous only. While waiting two months for culture and sensitivity results, trial and error can result in a wide variety of broad spectrum antibiotic usage, which can lead to other health complications including, but not limited to, intestinal dysbiosis.⁴ This case report discusses the unique challenges of identifying, diagnosing, and treating cutaneous mycobacterial infections, as well as addressing extraneous complications along the way.

Case Report

A 61-year-old caucasian female presented to the dermatology office with a complaint of a draining abscess to her right upper anterior thigh. Generally, she was in good health, and her medical history included an allergy to penicillin, hypertension, cervical radiculopathy with herniated discs. Medications included gabapentin, enalapril, hydrocodone with acetaminophen, and intermittent use of phentermine for weight loss. The patient reported she was helping a friend move, and she was exposed to various old boxes containing dirt and dust but does not specifically remember an injury to her leg. Prior to her arrival at the dermatology practice, she was seen by an urgent care clinic and was given doxycycline 100mg twice daily, along with trimethoprim/sulfmethoxazole 800mg twice daily, and a culture and sensitivity (C&S), was performed. She stated she was unable to take the doxycycline due to nausea, and she was told by urgent care a few days later her C&S was negative. Upon examination, she had a firm draining abscess to her right anterior thigh (Figure 1). She did not have any systemic symptoms such as fever, chills or sweats. The abscess was incised and drained again, and no further action was taken at this time given the negative C&S report. The patient was seen for a follow-up visit two weeks later, the wound had not fully closed from the incision, but the abscess appeared to remain drained. The patient was then seen two weeks later, and the abscess had reformed, along with a smaller adjacent abscess, and tender inguinal lymphadenopathy (Figure 2). The patient reported the abscess was not painful or tender, and her more concerning symptom was the discomfort she felt in the inguinal region related to lymphadenopathy. The abscess was easily drained by applying light pressure, and resulted in drainage from the smaller abscess, as if they were connected by a sinus tract. The drainage amount was significant, but not purulent and not keratinacious or cyst-like. The drainage had a light yellow appearance and could be described as watery. An aerobic and anaerobic C&S was repeated, and the patient was instructed to take doxycycline 50mg four times daily, to minimize nausea, but allow a 200mg daily total dose.

Doxycycline was chosen specifically because of its strong anti-inflammatory effect.⁵ The C&S results returned a few days later, and the result was, once again, negative for organisms. At this point, the differential diagnosis widened. Differential diagnoses included a cutaneous mycobacterial infection, atypical hidradenitis supurrativa, lymphgranuloma venereum, and atypical pyoderma gangrenosum. Laboratory studies were ordered, including complete blood count, comprehensive metabolic panel, sedimentation rate, and quantiferon gold. A punch biopsy was formed for standard pathology H&E, hematoxylin and eosin stain, as well as fresh tissues cultures for fungus, aerobic, anaerobic and mycobacterium. A note was placed on the H&E biopsy to run stains looking for organisms. Serological findings were within normal limits. White blood cells, sedimentation rate, and quantiferon were within normal limits. The H&E biopsy returned with a diagnosis of non specific granulomatous inflammation and ulcer. An addendum was later sent, which included a negative periodic acid-schiff stain, negative for organisms, and negative for acid-fast bacilli. The aerobic and anaerobic fresh tissues cultures were negative for organisms. Given the benign serology findings, benign H&E biopsy, partial tissue cultures, and the lack of fever, chills and sweats, the patient was given clarithromycin 500mg to treat for cutaneous mycobacterium,⁵ with the most likely causative agent, mycobacterium chelonae. The patient was closely monitored with daily check-ins, she tolerated the medication well, but after two weeks, did not see an improvement in symptoms, such as right inguinal lymphadenopathy, and both abscesses were still draining, although not as much as baseline. Approximately three weeks later, the patient was started on prednisone 40mg daily for inflammation related to lymphadenopathy. The patient was kept under close supervision with daily check-ins and advised to go to the emergency room with any fever, chills or sweats. Prednisone was given due to discomfort, and most safety concerns had been ruled out at this point, given negative serology, negative laboratory findings, and general lack of systemic systems, as well as broad spectrum coverage with antibiotics including clarithromycin to cover for mycobacterial infection. The patient responded well to prednisone, and her lymphadenopathy began to subside, her abscesses remained the same, and no other complications or systems presented. The patient was instructed to set up an appointment with infectious disease, in case a percutaneous intravenous line was needed to deliver medication. The prednisone was then slowly tapered while awaiting the remaining tissue cultures. At this point, the cultures were submitted over one month ago, and the laboratory was contacted for an estimated wait time­—they stated the tissue cultured for mycobacterium take eight weeks. During the waiting period, a critical alert fax was received from the laboratory, and results listed under the fungal culture, stated gram positive bacilli. This was puzzling, as the bacterial identification was found under the fungal culture, and the critical alert suggested a diagnosis of cutaneous anthrax. The presentation did not fit well for a cutaneous anthrax diagnosis, which typically has a black eschar appearance.⁷ The laboratory was generally unhelpful in discussing this case further, or explaining why this identification was found under a fungal culture. Nonetheless, the patient was started on ciprofloxacin 500mg twice daily for 60 days to cover for the potential of cutaneous anthrax. An additional two weeks passed, and the laboratory portal showed the mycobacterium fluorochrome smear was listed as a test not performed due to an unexpected system failure. The laboratory was contacted to ensure that the fresh tissues cultures were still being processed and not affected by the system failure that resulted in the swab culture not being done. The laboratory stated the cultures should be ready within 24 hours. Three days later, partial tissue cultures were received, and identified mycobacterium abscessus. The identified pathogen is also known as Mycobacteroides abscessus. Resistance was shown to all oral agents and many intravenous agents as well. However, the report noted that clarithromycin testing was still pending, and required a special sensitivity test, which could take an additional 72 hours. Once the final report was returned, clarithromycin was in fact, sensitive, at a minimum inhibitory concentration of 1mcg/mL. The patient had an appointment with infectious disease the next day and was switched to azithromycin 500mg daily with omadacycline (Nuzyra, Paratek Pharmaceuticals, Inc., Boston, MA) 300mg daily and continued to make a slow recovery.

Discussion

It is likely that many different specialties and medical fields encounter patients with cutaneous mycobacterial infections including dermatology, infectious disease, urgent care and emergency room centers as well as primary care practices. The difficult nature of identifying the initial cause, testing, susceptibility, as well as limited treatment options create a puzzle that contains many pieces with a high chance of failure if one piece is missing. Reflecting back, the diagnosis and appropriate treatments were started as quickly and as reasonably possible. There are however, three specific areas that could have been improved upon. The first is the notation that the drainage was not typical of a traditional staphylococcus infection. There was no way to know that the infection was a mycobacterial infection so early on, or the specific type, and its sensitivity, but the consistency and color of the drainage should have been given more weight. Second, as both serological and tissue tests were negative, the condition was narrowing away from an infectious etiology. After a few weeks of clarithromycin, the decision to start prednisone was made to address patient discomfort. Oral prednisone with an active cutaneous bacterial infection is not ideal, but in this particular case, it provided the patient comfort and did not appear to exacerbate her condition. Knowing the end result was infectious in nature, and that prednisone could exacerbate the condition,⁶ prednisone usage was a delicate balance between managing patient symptoms, comfort, and avoiding exacerbation of the condition. Third, was the decision to involve infectious disease at a later date, instead of earlier. There was a wait time for the patient to be seen, and it didn’t seem useful to involve infectious disease when initially there was no laboratory evidence of an infectious disease; however, the wider familiarity with this particular organism could potentially have prompted an earlier treatment option with azithryomycin, which was not tested in the C&S report. It is difficult to speculate why the patient responded poorly to clarithromycin given its susceptibility; there was no reason to suspect patient nonadherence, but anytime a proven treatment is ineffective, it would be wise to at least ponder that consideration. No further information was gained from the result of the gram positive bacilli finding under the fungal culture, as they did not further identify if the specimen was in fact cutaneous anthrax, or discuss the possibility of laboratory cross- contamination or an error in reporting. The H&E biopsy investigating the presence of acid-fast bacilli has been shown to stain positive in only 30 percent of cases for a related organism, mycobacterium marinum.⁸ The laboratory has no control over how fast an organism grows with current technology, but having to rely on an eight-week culture result, and additional time for sensitivity results, creates a guessing game of antibiotic choice, albeit, an educated guessing game.

Conclusion

After a few months of a puzzling mystery mixed with plenty of roadblocks along the way, the patient was expected to make a full recovery without any further complication. This case demonstrated the complicated nature of a quick diagnosis and treatment. If a mycobacterial infection is suspected, the earlier cultures are submitted the better, as an eight-month lag time prolongs the unknown. A few key takeaway elements include a high suspicion for a cutaneous mycobacterial infection if an abscess produces a discharge that is thinner and more pale yellow in appearance and is not nearly as painful or tender as a typical inflamed cyst or staphylococcus abscess. A negative aerobic and anaerobic C&S should also trigger suspicion of a mycobacterial infection. The third element was the addition of the second draining lesion, which appeared as if they were connected by a sinus tract; when one was palpated, the other expressed drainage. This case further highlights the need for improved testing, with a quicker turnaround time, as well as the need for more advancements in oral formulations of anti-mycobacterial antibiotics.

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