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

Abstract

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.

Post-tuberculosis chronic pulmonary aspergillosis: An emerging public health concern

“…In one study, co-isolation of Aspergillus in respiratory samples of patients with confirmed M. tuberculosis was achieved in 50 out of 140 (35.7%) patients, of whom 92% had underlying lung conditions, 35 (70%) had positive Aspergillus IgG, and 3 (6%) were confirmed to have CPA [33]. Among HIV-TB co-infected Ugandans, 9% of the patients had a positive Aspergillus IgG at the end of their TB treatment [35].…”

Opportunist Coinfections by Nontuberculous Mycobacteria and Fungi in Immunocompromised Patients

“…Person to person transmission has been suggested for M. abscessus but has not been fully demonstrated [68][69][70]. This ubiquity and exposure poses an enormous challenge for clinicians, since isolation of NTM from a clinical sample may only indicate a transient or persistent colonization, or an infection [71]. Aspergillus, Cryptococcus and Histoplasma, as typical environmental fungi, are not transmissible between humans.…”

“…the severity of the clinic manifestations being conditioned by the host immune status [93]. The existence of underlying pulmonary disease and immune disorders favor infections by both opportunistic pathogens fungi and NTM [71].…”

“…Acquired immunosuppression induced by drugs such as corticosteroids, chemotherapeutics to treat cancer, immunosuppressive drugs to prevent rejection after organ transplant, TNF-α antagonists and other biologic chemotherapeutics to treat inflammatory conditions, are other factors that could promote OPIs [68,71,94]. Macrophages play a key role in mycobacterial pathogenesis.…”

“…isolation in patients' samples. The case reports describe infection cases [116][117][118][119][120][121][122][123][124][125][126], but for several prospective and retrospective studies either it is not clear, or both infection and colonization are present [71,120,[127][128][129][130][131][132]. There is evidence that coinfection by fungal and mycobacterial spp.…”