Clinical significance of Aspergillus species isolated from respiratory specimens in patients with Mycobacterium avium complex lung disease

Chronic pulmonary aspergillosis: comprehensive insights into epidemiology, treatment, and unresolved challenges

Chronic pulmonary aspergillosis (CPA) is a challenging respiratory infection caused by the environmental fungus Aspergillus. CPA has a poor prognosis, with reported 1-year mortality rates ranging from 7% to 32% and 5-year mortality rates ranging from 38% to 52%. A comprehensive understanding of the pathogen, pathophysiology, risk factors, diagnosis, surgery, hemoptysis treatment, pharmacological therapy, and prognosis is essential to manage CPA effectively. In particular, Aspergillus drug resistance and cryptic species pose significant challenges. CPA lacks tissue invasion and has specific features such as aspergilloma. The most critical risk factor for the development of CPA is pulmonary cavitation. Diagnostic approaches vary by CPA subtype, with computed tomography (CT) imaging and Aspergillus IgG antibodies being key. Treatment strategies include surgery, hemoptysis management, and antifungal therapy. Surgery is the curative option. However, reported postoperative mortality rates range from 0% to 5% and complications range from 11% to 63%. Simple aspergilloma generally has a low postoperative mortality rate, making surgery the first choice. Hemoptysis, observed in 50% of CPA patients, is a significant symptom and can be life-threatening. Bronchial artery embolization achieves hemostasis in 64% to 100% of cases, but 50% experience recurrent hemoptysis. The efficacy of antifungal therapy for CPA varies, with itraconazole reported to be 43-76%, voriconazole 32-80%, posaconazole 44-61%, isavuconazole 82.7%, echinocandins 42-77%, and liposomal amphotericin B 52-73%. Combinatorial treatments such as bronchoscopic triazole administration, inhalation, or direct injection of amphotericin B at the site of infection also show efficacy. A treatment duration of more than 6 months is recommended, with better efficacy reported for periods of more than 1 year. In anticipation of improvements in CPA management, ongoing advances in basic and clinical research are expected to contribute to the future of CPA management.

A Systematic Review of Factors Associated with Mortality among Patients with Mycobacterium avium Complex Lung Disease

PURPOSE

As the number of patients with Mycobacterium avium complex lung disease is significantly increasing worldwide, several studies have focused on the prognostic factors associated with the disease. This systematic review investigated the factors associated with mortality among patients with Mycobacterium avium complex lung disease.

METHODS

Two investigators independently identified studies that were designed to determine risk factors for mortality in patients with Mycobacterium avium complex lung disease from PubMed, the Cochrane Register of Control Trial database, and EMBASE (accessed on 25 November 2022).

RESULTS

Of the 1133 titles and abstracts screened, 54 full texts were selected for review, and 15 studies were finally included in this systematic review. The most commonly studied risk factors were advanced age and low body mass index (11 studies for each), followed by male sex (8 studies), hypoalbuminemia (5 studies), and cavity (5 studies). In each study, these factors were mostly associated with increased all-cause mortality among patients with Mycobacterium avium complex lung disease as confirmed via multivariate analysis.

CONCLUSIONS

Advanced age, male sex, low body mass index, hypoalbuminemia, and cavity are likely to be the common risk factors for all-cause mortality among patients with Mycobacterium avium complex lung disease, suggesting that patients with these factors need to be carefully monitored.

Risk factors for clinical progression in patients with pulmonary Mycobacterium avium complex disease without culture-positive sputum: a single-center, retrospective study

OBJECTIVES

Limited data are available on the progression of pulmonary Mycobacterium avium complex (MAC) disease without culture-positive sputum. The aim of this study was to identify the risk factors associated with clinical progression of pulmonary MAC disease diagnosed by bronchoscopy.

METHODS

A single-center, retrospective, observational study was conducted. Pulmonary MAC patients diagnosed by bronchoscopy without culture-positive sputum from January 1, 2013, to December 31, 2017 were analyzed. Clinical progression after diagnosis was defined as having culture-positive sputum at least once or initiation of guideline-based therapy. Then, clinical characteristics were compared between clinically progressed patients and stable patients.

RESULTS

Ninety-three pulmonary MAC patients diagnosed by bronchoscopy were included in the analysis. During the 4-year period after diagnosis, 38 patients (40.9%) started treatment, and 35 patients (37.6%) had new culture-positive sputum. Consequently, 52 patients (55.9%) were classified into the progressed group, and 41 patients (44.1%) were classified into the stable group. There were no significant differences between the progressed and the stable groups in age, body mass index, smoking status, comorbidities, symptoms, or species isolated from bronchoscopy. On multivariate analysis, male sex, monocyte to lymphocyte ratio (MLR) ≥ 0.17, and the presence of combined lesions in the middle (lingula) and lower lobes were risk factors for clinical progression.

CONCLUSIONS

Some patients with pulmonary MAC disease without culture-positive sputum progress within 4 years. Therefore, pulmonary MAC patients, especially male patients, having higher MLR or lesions in the middle (lingula) and lower lobes might need careful follow-up for a longer time.

Clinical features and treatment outcomes of pulmonary Mycobacterium avium-intracellulare complex with and without co-infections

Coinfections are more common in patients with cystic fibrosis and bronchiectasis. Infiltrates on imaging studies are seen more commonly in patients with coinfections, but coinfections did not affect treatment outcomes of pulmonary Mycobacterium avium complex.

Aspergillus isolation in nontuberculous mycobacterial pulmonary disease: Associated with antimycobacterial treatment initiation but not response

PURPOSE

Chronic pulmonary aspergillosis is a serious complication of nontuberculous mycobacterial pulmonary disease (NTM-PD), and diagnosis remains challenging. The present study examined associations between the respiratory isolation of Aspergillus and the clinical characteristics and treatment outcomes of patients with NTM-PD.

METHODS

All patients meeting NTM-PD criteria as defined by the ATS/IDSA statement, with at least one respiratory sample cultured for fungi, were included in this retrospective cohort analysis. Patients with at least one respiratory sample isolating Aspergillus were compared to patients who did not isolate Aspergillus. The primary outcomes were culture conversion and radiologic evolution 12 months after NTM-PD treatment initiation.

RESULTS

During a 12 year period, 497 patients meeting the inclusion criteria were seen in our tertiary care center, of whom 130 grew Aspergillus. Median follow up after NTM-PD diagnosis was 46 months. Inhaled corticosteroid use, a nodular-bronchiectatic CT pattern and NTM-PD treatment initiation were more frequent in patients who isolated Aspergillus compared to those who did not (p-value respectively 0.01, 0.03 and < 0.001). Rates of culture conversion (63.0% vs. 62.2%, respectively; p-value 1) and radiologic evolution (improvement or stability in 69.7% vs. 77.2%, respectively; p-value 0.25) were not significantly different between treatment groups. Likewise, culture reversion rate and 5-year mortality were not significantly different. Additionally, A. fumigatus and repeated detection of Aspergillus were not associated with treatment outcomes.

CONCLUSION

There was no association between respiratory isolation of Aspergillus and NTM-PD treatment outcomes in this cohort. However, treatment for NTM-PD was initiated more frequently in patients who isolated Aspergillus.

New/Different Look at the Presence of Aspergillus in Mycobacterial Pulmonary Diseases. Long-Term Retrospective Cohort Study

Chronic pulmonary aspergillosis (CPA) has been reported to be associated with poor prognosis in non-tuberculous mycobacteria (NTM)-pulmonary disease (PD) patients. However, whether isolation of Apergillus species is associated with poor outcome or mostly just the reflection of colonization is a widely debated issue and a yet unsolved question. We conducted this single-centered retrospective cohort study of 409 NTM-PD patients to assess the impacts and prevalence of Aspergillus isolation and CPA development. The median observation time was 85 months. Aspergillus species were isolated from 79 (19.3%) and 23 (5.6%) developed CPA. Isolation of Aspergillus species was not associated with mortality in NTM-PD patients (p = 0.9016). Multivariate logistic regression analysis revealed that higher CRP (p = 0.0213) and AFB stain positivity (p = 0.0101) were independently associated with Aspergillus isolation. Different mycobacterial species were not associated with Aspergillus isolation. Survival curves for patients with CPA diagnosis were significantly and strikingly different from those without (p = 0.0064), suggesting that CPA development severely affects clinical outcome. Multivariate logistic regression analysis revealed that the use of systemic steroids (p = 0.0189) and cavity (p = 0.0207) were independent risk factors for the progression to CPA. Considering the high mortality rate of CPA in NTM-PD, early diagnosis and treatment are essential to improve outcomes for NTM-PD patients.

Chronic Pulmonary Aspergillosis Following Nontuberculous Mycobacterial Infections: An Emerging Disease

Chronic pulmonary aspergillosis (CPA) following nontuberculous mycobacterial (NTM) lung disease is being increasingly recognized, especially in countries where tuberculosis is not endemic, with an incidence rate of 3.9–16.7%. NTM lung disease has been identified as a predictor of mortality in CPA patients. The major risk factors for NTM-associated CPA include fibrocavitary NTM lung disease, the presence of pulmonary emphysema, and high-dose corticosteroid use. The onset of CPA is 1.5–7 years following the diagnosis of NTM lung disease. The diagnosis can be made using standard criteria; however, serological diagnosis using Aspergillus precipitin has demonstrated a higher sensitivity and specificity when compared with fungal culture from respiratory specimens. Treatment is challenging since rifampicin and oral triazoles should not be used concomitantly. The prognosis is poor, and the factors associated with worse prognosis are corticosteroid use and high C-reactive protein level.

Opportunist Coinfections by Nontuberculous Mycobacteria and Fungi in Immunocompromised Patients

Nontuberculous mycobacteria (NTM) and many fungal species (spp.) are commonly associated with opportunistic infections (OPIs) in immunocompromised individuals. Moreover, occurrence of concomitant infection by NTM (mainly spp. of Mycobacterium avium complex and Mycobacterium abscessus complex) and fungal spp. (mainly, Aspergillus fumigatus, Histoplasma capsulatum and Cryptococcus neoformans) is very challenging and is associated with poor patient prognosis. The most frequent clinical symptoms for coinfection and infection by single agents (fungi or NTM) are similar. For this reason, the accurate identification of the aetiological agent(s) is crucial to select the best treatment approach. Despite the significance of this topic it has not been sufficiently addressed in the literature. This review aims at summarizing case reports and studies on NTM and fungi coinfection during the last 20 years. In addition, it briefly characterizes OPIs and coinfection, describes key features of opportunistic pathogens (e.g., NTM and fungi) and human host predisposing conditions to OPIs onset and outcome. The review could interest a wide spectrum of audiences, including medical doctors and scientists, to improve awareness of these infections, leading to early identification in clinical settings and increasing research in the field. Improved diagnosis and availability of therapeutic options might contribute to improve the prognosis of patients’ survival.

Concomitant Presence of Aspergillus Species and Mycobacterium Species in the Respiratory Tract of Patients: Underestimated Co-occurrence?

Objectives

Aspergillus and Mycobacterium are opportunistic pathogens that can cause severe pulmonary diseases. To date, the clinical significance of their concomitant isolation and potential interactions in the lung remains poorly understood. The aim of this study was to assess the prevalence of their concomitant isolation from respiratory samples, and to depict the related clinical and microbiological characteristics.

Methods

A retrospective monocentric study was conducted from January 2011 to December 2017, including all in-patients from whom positive cultures of Aspergillus and Mycobacterium were obtained on respiratory samples within a 3-month period. Clinical, radiological and laboratory data were analyzed. Patients were categorized by a clinical and microbiological committee as "infected" or "colonized" by both pathogens according to current guidelines.

Results

Overall, 140 patients had ≥1 respiratory samples positive for Mycobacterium and concomitantly sent for fungal culture, and 708 were positive for Aspergillus, concomitantly sent for mycobacterial culture. Only 50 had at least one positive culture for both Mycobacterium sp. and Aspergillus sp. Men represented 63% of patients, mean age was 61 years. A third of patients were immunocompromised and 92% had underlying lung diseases. Aspergillus was primarily found as a colonizing agent. Proportion of Mycobacterium Avium Complex (p = 0.02) was higher in patients co-carrying Aspergillus spp.

Conclusion

In this first study focusing on co-isolation of Mycobacteria and Aspergillus in patient's respiratory samples, co-infection remains rare. Further studies are warranted in order to precise the exact relationship between these opportunistic pathogens and the clinical impact of co-isolations.