Fungal-Bacterial Di-Kingdom Microbial Communities Associated with Chronic Pulmonary Disease

Abstract

Fungal-bacterial co-colonization and co-infections are emerging among TB-suspected patients, yet the underlying mechanisms that enable and arise from their interactions are poorly understood. Understanding how environmental microbes such as fungi and bacteria co-evolve and develop traits to evade host immune responses and resist treatment is critical to controlling opportunistic co-infections. Our previous work has demonstrated that fungal-bacterial interactions can have dramatic impacts on fungal pathogenesis and drug resistance. Here, we, therefore, hypothesize that cross-kingdom synergistic interactions between environmental fungi and bacteria may influence both fungal and bacterial virulence, antimicrobial resistance patterns and aetiology. Through this, we aimed to establish the prevalence of fungal–bacterial microbial communities associated with chronic primary or opportunistic pulmonary infections. Concordantly, through surveilling 302 clinical samples from 151 patients, we established the prevalence of TB (0.7%) to be lower than that of fungi (1.3%) and non-TB bacterial (4.6%) mono-aetiologies Figure 2. However, our main observation was the unexpected taxonomic diversity with a striking twist of fungal-bacterial di-kingdom aetiological conformities. Interestingly, the majority of the patients presented with at least a di or mono-kingdom aetiological pairings. Importantly, fungi and non-TB bacteria formerly regarded as atypical opportunists are now frequently isolated as possible aetiology for chronic pulmonary infection. Hence, we revealed many di-kingdom aetiological pairings here but their significance remains a question of further examination. Among which Acremonium spp + K. pneumoniae (n=5), Acremonium spp +Streptococcus pneumoniae (n=4), Acremonium spp + C. albicans + K. pneumoniae (n=3) were among the most dominant aetiological pairings observed. Interestingly, Acremonium spp + K. pneumoniae pairings were also seen to be the most commonly associated with pulmonary TB both during and after treatment. Isolation from the same infection niche as seen here calls for further investigations into any interaction signatures that may exist between these organisms. Taken together, our data suggest that fungal-bacterial co-existence may influence their virulence attributes and antimicrobial resistance patterns, with relevance to patient outcomes. Therefore, our data reveals an array of fungal-bacterial pairings that may influence the prognosis of chronic pulmonary disease. Importantly, suggesting that the diversity of pulmonary infective fungi and bacteria, and their complex population structures may pose challenges to the analysis and interpretation of conventional data. Thus, there is a need to redirect our diagnostic approaches to encompass polymicrobial aetiology in order to enhance our suspicion index for better management of opportunistic fungal-bacterial co-infections.