Non-Ventilator-Associated Hospital-Acquired Pneumonia: Implications for the Clinical Laboratory

Health care-associated pneumonia develops after >48 h of hospitalization; it is sub-categorized as ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP). HAP is further sub-categorized based on a patient's need for mechanical ventilation. Case definitions include patients requiring mechanical ventilation (V-HAP) or not requiring ventilation (NV-HAP). As of 2020, case definitions, clinical diagnosis, surveillance criteria, and laboratory-based criteria for NV-HAP are not fully standardized and are not commonly used. Therefore, substantial variability in descriptions of NV-HAP exists worldwide. Comparison of NV-HAP rates between health care organizations is challenging. Ideally, a combination of clinical and laboratory findings should improve the NV-HAP case definition and enhance the predictive power of all pneumonia diagnoses, including NV-HAP. Clinical laboratories can explore emerging technology and develop collaborative, interdisciplinary relationships to improve the real-time identification of NV-HAP cases. Monitoring the downstream impact and improvements of such technology is of critical importance. The review describes the current epidemiology, risk factors, etiology, diagnosis, treatment, and clinical outcomes of NV-HAP. Molecular microbiology testing methods are discussed.