Incidence and management of mycobacterial infection in solid organ transplant recipients

Management and prophylaxis of bacterial and mycobacterial infections among lung transplant recipients

Bacterial and mycobacterial infections are associated with morbidity and mortality in lung transplant recipients. Infectious complications are categorized by timing post-transplant: <1, 1–6, and >6 months. The first month post-transplant is associated with the highest risk of infection. During this period, infections are most commonly healthcare-associated, and include infections related to surgical complications. The lungs and bloodstream are common sites of infections. Common healthcare-associated organisms include methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative bacilli such as Pseudomonas aeruginosa, and Clostridioides difficile. More than 1-month post-transplant, opportunistic infections can occur. Tuberculosis occurs in 0.8–10% of lung transplant recipients which reflects variation in background prevalence. The majority of post-transplant tuberculosis stems from reactivation of untreated or undiagnosed latent tuberculosis. Most post-transplant tuberculosis occurs in the lungs and develops within a year of transplant. Non-tuberculous mycobacteria commonly colonize the lungs of lung transplant candidates and are often hard to eradicate even with prolonged courses of antimycobacterial agents. Drug interactions between antimycobacterial agents and calcineurin and mTOR inhibitors also complicates treatment post-transplant. Given that infection adversely impacts outcomes after lung transplant, and that anti-infective therapy is often less effective after transplant, infection prevention is key to long-term success. A comprehensive approach that includes pre-transplant evaluation, perioperative prophylaxis, long-term antimicrobial prophylaxis, immunization, and safer living at home and in the community, should be employed to minimize the risk of infection.

Management of infections due to nontuberculous mycobacteria in solid organ transplant recipients-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the epidemiology, diagnosis, prevention, and management of nontuberculous mycobacterial infections in the pre- and post-transplant period. NTM commonly cause one of five different clinical syndromes: pleuropulmonary disease, skin and soft tissue infection, osteoarticular infection, disseminated disease, including that caused by catheter-associated infection, and lymphadenitis. Diagnosis of these infections can be challenging, particularly when they are isolated from nonsterile spaces, owing to their ubiquity in nature. Consequently, diagnosis of pulmonary infections with these pathogens requires fulfillment of microbiologic, radiographic, and clinical criteria to address this concern. A combination of culture and molecular diagnostic techniques is often required to make a species-level identification. Treatment varies depending on the species isolated and is complex, owing to drug toxicities, need for long-term multidrug regimens, and consideration of complex drug-drug interactions between antimicrobials and immunosuppressive agents. Given these treatment challenges, efforts should be made in both the hospital and community settings to limit exposure to these pathogens to the extent feasible.

Epidemiology and Outcomes of Nontuberculous Mycobacterial Infections in Solid Organ Transplant Recipients at a Midwestern Center

BACKGROUND

Nontuberculous mycobacterial (NTM) infections have the potential to affect outcomes in solid organ transplant (SOT) recipients.

METHODS

Retrospective cohort of adults who underwent SOT at a Midwestern hospital between January 1, 2004, and December 31, 2013. NTM-infected patients had at least 1 positive culture for NTM posttransplant. NTM disease was defined by 1) American Thoracic Society/Infectious Disease Society of America criteria for respiratory specimens or 2) NTM cultured from a sterile site with a compatible clinical syndrome. The remaining NTM infected patients were classified as colonized. Cox regression analysis was used to determine the association of NTM with mortality among lung transplant recipients.

RESULTS

Of 3338 SOT recipients, 50 (1.5%) had NTM infection during a median 1038 days (range, 165-3706) follow-up posttransplant. Forty-three patients (86%) with NTM infection were lung transplant recipients; 18 of 43 (41.8%) were treated for NTM and 6 (13.9%) met disease criteria. Isolation of the same species on multiple occasions was associated with treatment among the colonized lung transplant recipients (8/12 [67%] vs 3/25 [12%] who were not treated, P = 0.014). NTM infection was not associated with increased mortality in lung transplant recipients (9/43 [20.9%] in infected died versus 161/510 [31.6%] in uninfected, age-adjusted hazard ratio, 0.56; 95% confidence interval, 0.2-1.1; P = 0.091). Three of 6 lung transplant recipients with NTM disease died compared with 6 of 37 colonized (hazard ratio, 7.0; 95% confidence interval, 1.5-31.5; P = 0.003).

CONCLUSIONS

Among SOT patients, NTM were most frequently identified from lung transplant recipients. NTM infection was not associated with increased mortality, although NTM disease was associated with increased mortality compared with colonization in lung transplant recipients.

Early onset of nontuberculous mycobacterial pulmonary disease contributes to the lethal outcome in lung transplant recipients: report of two cases and review of the literature

Lung transplant (LuTx) recipients represent a population at risk of nontuberculous mycobacterial pulmonary disease (NTM-PD). Yet the risk factors, the timing of NTM-PD after transplantation, and the association with allograft dysfunction all remain poorly defined. We report 2 cases of early-onset NTM-PD and review the literature, focusing on NTM-PD in LuTx recipients not colonized with NTM prior to transplantation. In addition, we summarize the main characteristics and differences between early- and late-onset disease.

Clinical features and outcomes of tuberculosis in transplant recipients as compared with the general population: a retrospective matched cohort study

There are no previous studies comparing tuberculosis in transplant recipients (TRs) with other hosts. We compared the characteristics and outcomes of tuberculosis in TRs and patients from the general population. Twenty-two TRs who developed tuberculosis from 1996 through 2010 at a tertiary hospital were included. Each TR was matched by age, gender and year of diagnosis with four controls selected from among non-TR non-human immunodeficiency virus patients with tuberculosis. TRs (21 patients, 96%) had more factors predisposing to tuberculosis than non-TRs (33, 38%) (p <0.001). Pulmonary tuberculosis was more common in non-TRs (77 (88%) vs. 12 TRs (55%); p 0.001); disseminated tuberculosis was more frequent in TRs (five (23%) vs. four non-TRs (5%); p 0.005). Time from clinical suspicion of tuberculosis to definitive diagnosis was longer in TRs (median of 14 days) than in non-TRs (median of 0 days) (p <0.001), and invasive procedures were more often required (12 (55%) TRs and 15 (17%) non-TRs, respectively; p 0.001). Tuberculosis was diagnosed post-mortem in three TRs (14%) and in no non-TRs (p <0.001). Rates of toxicity associated with antituberculous therapy were 38% in TRs (six patients) and 10% (seven patients) in non-TRs (p 0.014). Tuberculosis-related mortality rates in TRs and non-TRs were 18% and 6%, respectively (p 0.057). The adjusted Cox regression analysis showed that the only predictor of tuberculosis-related mortality was a higher number of organs with tuberculosis involvement (adjusted hazard ratio 8.6; 95% CI 1.2-63). In conclusion, manifestations of tuberculosis in TRs differ from those in normal hosts. Post-transplant tuberculosis resists timely diagnosis, and is associated with a higher risk of death before a diagnosis can be made.

Fatal aortic pseudoaneurysm from disseminated Mycobacterium kansasii infection: case report

Mycobacterium kansasii is a photochromogenic, slow-growing mycobacterium species that can cause pulmonary infection in patients with predisposing lung diseases, as well as extrapulmonary or disseminated disease in immunosuppressed patients. We describe a patient with a myelodysplastic syndrome, disseminated M kansasii infection, and ruptured aortic aneurysm. He had a recent diagnosis of mycobacterium cavitary lung lesions and was transferred to our facility for possible surgical intervention of an aortic aneurysm. Few hours after admission, the patient suddenly collapsed and died despite resuscitation efforts. A complete autopsy was performed and showed ruptured ascending aortic pseudoaneurysm with hemopericardium, disseminated necrotizing and nonnecrotizing granulomas with acid-fast bacilli in the aortic wall, lungs, heart, liver, spleen, and kidneys. Further genetic studies were consistent with monocytopenia and mycobacterial infection syndrome.

Risk factors for nontuberculous mycobacterial infections in solid organ transplant recipients: a case-control study

BACKGROUND

The epidemiology of nontuberculous mycobacteria (NTM) disease in solid organ transplant recipients is poorly defined.

METHODS

We identified all solid organ transplant recipients with NTM disease at a single center over a 7.5-year period, and collected data on patient demographics, co-morbidities, immunosuppressive medications, and rejection. We conducted a case-control study to identify risk factors for disease, matching 3 control patients to each case patient by date of transplantation.

RESULTS

A total of 34 cases of NTM disease occurred during the study period, involving 6 single lung, 13 bilateral lung, 8 heart, 4 liver, 2 kidney, and 1 pancreas-kidney recipients. Cases were predominantly male (24/34), with a median age of 55 years (interquartile range [IQR]: 46-61 years), and developed after a median of 8 months post transplantation (IQR: 2-87 months). Mycobacterium abscessus and Mycobacterium avium complex were the most common pathogens, and the lung (including pleura) was the most common site of disease. In the adjusted case-control analysis, lung transplant recipients had the highest risk of NTM disease.

CONCLUSIONS

Additional studies are needed to evaluate the role of targeted surveillance measures for NTM disease in high-risk patients, particularly lung transplant recipients, and to characterize the mechanisms of disease acquisition.