Title : Mycobacterium abscessus complex causing rapidly progressive necrotizing pneumonia
Abstract:
Introduction:
Mycobacterium abscessus complex is a group of fast growing, multidrug resistant mycobacteria that are clinically challenging to treat given rapid progression and antibiotic resistance patterns of this group. Treatment for this group requires a multidrug regimen for long durations with relatively poor overall resolution and high risk of side effects. We present a case of rapidly progressive mycobacterium abscessus causing necrotizing pneumonia complicated by a bronchopulmonary fistula and subcutaneous emphysema.
Case Description:
Our patient is a 71-year-old female with a medical history significant for mycobacterium abscessus causing severe bronchiectasis previously treated with azithromycin, and hypothyroidism that initially presented with hemoptysis and shortness of breath. Initial imaging showed likely right lower lobe pulmonary artery hemorrhage, large right upper lobe cavitary lesion, and extensive right lower lobe cavitation. She underwent IR embolization for the pulmonary artery hemorrhage. Empiric antimicrobials consisting of piperacillin-tazobactam, linezolid, and voriconazole were started. She was admitted to the ICU for septic shock and acute hypoxic respiratory failure requiring intubation. On serial imaging she developed a loculated pneumothorax, the consolidative findings on the right rapidly progressed, and she developed new consolidations on the left. She also developed substantial subcutaneous emphysema that was present on imaging and physical exam. Given rapid progression and continued clinical deterioration with overall poor prognosis, the family opted to transition the patient to comfort care, and she passed shortly thereafter.
Discussion:
Mycobacterium abscessus complex most commonly causes skin/soft tissue infections and pulmonary infections but has been associated with infections in virtually all organ systems.1 Treatment is due to high rates of resistance to macrolides, which comes from an inducible erm41 gene that is present in approximately 20% of isolates in the United States.2,3 Treatment to macrolide susceptible strains requires at least three medications, while treatment of macrolide resistant strains requires at least four medications.2 Antimicrobials commonly used include amikacin, imipenem/cefoxitin, tigecycline, azithromycin/clarithromycin, clofazimine, and linezolid.2 Ideal treatment duration is unclear due to a lack of robust data, but recommendations are typically to treat for at least 12 months, with at least 4 months of those being with parenteral therapy.2
Conclusion:
Mycobacterium abscessus complex infection confers significant mortality/morbidity, with up to 15% of patients experiencing impaired quality of life or death, given its rapid clinical progression and rising prevalence of resistance to antimicrobials, especially due to the erm41 gene.3,4 Treatment should ideally be started after acquiring susceptibility results and should be done in conjunction with infectious disease specialists given the need for close monitoring of progression and medication side effects.2 Furthermore, nontuberculous mycobacterium infections overall have several shortcomings in current treatment strategies - development of additional antimicrobial therapeutics and further delineation of optimal treatment strategies are needed.2 This case highlights the need for having efficacious treatment options without significant toxicity as this would likely have led to the patient pursuing more aggressive early treatment and avoiding progression of the infection to this extent.
