Introduction: Aspiration pneumonia is a subclass of community-acquired pneumonia that is expected to have an increasing contribution in mortality and morbidity, particularly in the elderly population over the next coming decades. While studies have revealed significant progress in identifying risk factors for aspiration pneumonia, the clinical presentation and diagnosis remain challenging to healthcare providers. Areas covered: We conducted a broad literature review using the MeSH heading in PubMed/MEDLINE of 'aspiration pneumonia' from January 1970 to July 2019. The understanding of the microbiology of aspiration pneumonia has evolved from a possible shift in the causative organisms away from anaerobes to traditional community-acquired pneumonia organisms. The importance of this shift is not yet known, but it has questioned the pathogenic role of anaerobes, appropriate anaerobic testing and the role of these pathogens in the pulmonary microbiome in patients with pneumonia. The identification of risk factors led to strategies to prevent or minimize the risk of aspiration pneumonia with moderate success. Expert opinion: Our expert opinion is that further research is needed to determine the role of the microbiome with aspiration pneumonia and patient risk factors. There is also a great need to develop clinical tools to help providers diagnose, treat, and prevent aspiration pneumonia.
Keywords: Aspiration; anaerobes; community-acquired; microbiome; pneumonia.