Etiology of community-acquired pneumonia in Western Australian metropolitan hospitals: Missed opportunities for pneumococcal vaccination

Background and Objectives: Community-Acquired Pneumonia (CAP) is a leading cause of hospitalization and death worldwide. Knowledge of local pathogens guides antimicrobial treatment, however the etiology of CAP in Western Australia has not been well studied. We hypothesized that Streptococcus pneumonia, Chlamydia pneumonia, Mycoplasma pneumonia and respiratory viruses would be common pathogens detected in patients hospitalized with CAP. We further hypothesized that the pneumococcal vaccination would impact upon rates of Streptococcus pneumonia detection. Methods: A retrospective analysis of two hospital medical record databases identified all patients 18 years or older admitted with CAP in 2015. Patients with recent hospitalization, significant immune suppression, chronic respiratory disease or active cancer were excluded. All investigations ordered during admission were reviewed. Results: 184 patients met the necessary criteria with radiographic evidence and clinical features of CAP. Mean age was 66 years (range, 20-96), 19 patients required admission to intensive care and 3 patients died. There were 75 pathogens detected in 55 patients (30%). The most common pathogens detected were influenza virus (7%), Streptococcus pneumonia (7%) and Haemophilus influenza (7%). Only one of seven ‘high-risk’ patients with isolated Streptococcus pneumonia was appropriately vaccinated. Conclusions: Causative agents were not detected in the majority of patients. Bacteria were most frequently detected, however influenza virus was the most common single pathogen detected. There were missed opportunities in administering pneumococcal vaccinations in the community. We believe a prospective study ensuring consistent and updated diagnostic protocols is overdue