A small study looked at older adults in the emergency room with breathing trouble and tested whether blood levels of the natural peptide LL‑37 (and other antimicrobial peptides) could help tell if they have pneumonia. The researchers found that LL‑37 and a couple of other peptides showed some promise as markers, but the results are still early and not ready for everyday use.

Pneumonia, chronic obstructive pulmonary disease (COPD), and heart failure (HF) exacerbations can present similarly in the older adult in the Emergency Department (ED), leading to sub-optimal treatment from over- and under-diagnosis. There may be a role for antimicrobial peptides (AMPs) in improving the accurate diagnosis of pneumonia in these patients. This pilot was a prospective, observational cohort study of older adults (aged ≥65 years of age) who presented to the ED with dyspnea or elevated respiratory rate. To identify biomarkers of pneumonia, serum levels of white blood cell count, procalcitonin (PCT), and antimicrobial peptides (human beta defensin 1 and 2 [HBD-1, -2], human neutrophil peptides 1–3 [HNP1–3] and cathelididin [LL-37]) were compared between those with and without pneumonia. Criterion standard reviewers retrospectively determined the diagnoses present in the ED. Three hundred ninety-one patients were screened, 140 were eligible, and 79 were enrolled. Based on criterion standard review, pneumonia was present in 10 (12.7%), COPD in 9 (11.4%) and HF in 31 (39.2%) with a co-diagnosis rate of 10.1% by criterion standard review. Comparatively, emergency medicine attending physicians diagnosed pneumonia in 16 (20.3%), COPD in 12 (15.2%), and HF in 30 (38.0%) with co-diagnosis rate of 15.2%. Emergency physicians agreed with criterion standard diagnoses in 90% of pneumonia, 75% of COPD and 65% of HF diagnoses. Differences in leukocyte count (p<0.01) and two novel AMPs (DEFA5 (p=0.08) and DEFB2 (p=0.09)) showed promise for diagnosing pneumonia. Emergency physicians continue to have poor diagnostic accuracy in dyspneic older adult patients. Serum AMP levels are one potential tool to improve diagnostic accuracy and outcomes for this important population and require further study.