Literature review on micro-organisms from domestic goats potentially causing human pneumonia

Background: In the Netherlands, living in proximity to goat farms has been consistently associated with an increased incidence of community-acquired pneumonia (CAP). The cause remains largely unknown though airborne microbial agents could play a role. Objective: The aim of this study is to explore micro-organisms present in goats that can cause human pneumonia. Methods: An extensive literature review was conducted to identify all micro-organisms detected in goats that are associated with human pneumonia. Additionally, the identified micro-organisms were prioritized using a self-developed scoring system and expert opinion. Results: Through extensive literature review, 4309 references describing 302 different micro-organisms in goats or on goat farms were identified. Additional searches and reviews for human respiratory disease caused by each of these micro-organisms yielded a final list of 76 bacteria, 7 viruses, 7 fungi, and 6 protozoa. They were assigned scores based on pneumonia type, diagnosis of respiratory disease, patient immune status, and evidence strength. Based on these scores, the most likely potential causal micro-organisms included Moraxella spp. Chlamydia psittaci, Staphylococcus aureus, and Streptococcus pneumoniae. Subsequently, the list of micro-organisms was reviewed by external experts on their perceived likelihood of the organism causing this CAP. Conclusion: Results of this literature study can give insight into the possible causes of pneumonia. Nonetheless, no unambiguous conclusion on the actual cause of the increased CAP risk around goat farms can be drawn solely based on these results.