Invasive Mycobacterium abscessus Complex Infection After Cardiac Surgery: Epidemiology, Management, and Clinical Outcomes

Abstract

Background: We recently mitigated a clonal outbreak of hospital-acquired Mycobacterium abscessus complex (MABC), which included a large cluster of adult patients who developed invasive infection after exposure to heater-cooler units during cardiac surgery. Recent studies have detailed Mycobacterium chimaera infections acquired during cardiac surgery; however, little is known about the epidemiology and clinical courses of cardiac surgery patients with invasive MABC infection.

Methods: We retrospectively collected clinical data on all patients who underwent cardiac surgery at our hospital and subsequently had positive cultures for MABC from 2013 through 2016. Patients with ventricular assist devices or heart transplants were excluded. We analyzed patient characteristics, antimicrobial therapy, surgical interventions, and clinical outcomes.

Results: Ten cardiac surgery patients developed invasive, extrapulmonary infection from M. abscessus subspecies abscessus in an outbreak setting. Median time from presumed inoculation in the operating room to first positive culture was 53 days (interquartile range [IQR], 38-139 days). Disseminated infection was common, and the most frequent culture-positive sites were mediastinum (n = 7) and blood (n = 7). Patients received a median of 24 weeks (IQR, 5-33 weeks) of combination antimicrobial therapy that included multiple intravenous agents. Six patients required antibiotic changes due to adverse events attributed to amikacin, linezolid, or tigecycline. Eight patients underwent surgical management, and 6 patients required multiple sternal debridements. Eight patients died within 2 years of diagnosis, including 4 deaths directly attributable to MABC infection.

Conclusions: Despite aggressive medical and surgical management, invasive MABC infection after cardiac surgery caused substantial morbidity and mortality. New treatment strategies are needed, and compliance with infection prevention guidelines remains critical.

Keywords: Mycobacterium abscessus; hospital outbreak; nontuberculous mycobacteria.

Figure 1.

Clinical photographs of Mycobacterium abscessus subsp abscessus infections following cardiac surgery. A, Sternal wound at time of diagnosis of M. abscessus subsp abscessus mediastinal infection. B, Sternal wound and abdominal wall abscess in patient with chronic M. abscessus subsp abscessus mediastinal infection and infected epicardial pacing lead at abdominal wall. In this cohort, disseminated infection commonly presented with mild, nonpurulent drainage from sternal wounds.

Figure 2.

Clinical courses of 10 patients who developed invasive Mycobacterium abscessus subsp abscessus infection after cardiac surgery. Incubation period is given from time of presumed inoculation in operating room to time that the first positive culture was obtained. Time periods of antibiotic therapy are given in weeks.

Figure 3.

Antibiotic-associated adverse events experienced by 10 cardiac surgery patients treated for invasive Mycobacterium abscessus subsp abscessus infection. Therapy-limiting adverse events required changes in antibiotic regimen. Gastrointestinal (GI) adverse events consisted of nausea, vomiting, or diarrhea. Both patients with ototoxicity developed hearing loss and tinnitus. The single hematologic adverse event was thrombocytopenia. One patient experienced 2 distinct GI adverse events attributed to different antibiotics; this patient’s GI symptoms are represented by a single bar on the figure. Abbreviation: C. difficile, Clostridioides difficile.