CTTI Risk Factors for HABP/VABP Study

Inclusion Criteria (Adult arm =\> 18 years old): * Admission to participating ICU * Hospitalized for \>48 hours or admitted \<7 days after discharge from an inpatient acute or chronic care facility High-Risk Inclusion (Adult arm =\> 18 years old): Treated with one or more of the following respiratory modalities for at least 12 hours, either currently or within the prior 7 days: * Invasive mechanical ventilation * Noninvasive ventilation (BiPAP or CPAP for any indication other than obstructive sleep apnea) * High-flow, supplemental oxygen therapy via nasal cannula. Only include systems that using an air/oxygen blender capable of delivering a precise FiO2 level, not just a flow in LPM. * High flow supplemental oxygen therapy delivering at least 50% FiO2 via aerosol facemask or tracheostomy collar (mask). Only include systems using an air/oxygen blender capable of delivering a precise FiO2 level, not just a flow in LPM. * Supplemental oxygen therapy delivered via either partial or non-rebreather face mask Other-ICU Inclusion(Adult arm =\> 18 years old): All patients who meet ICU and time-frame eligibility criteria, but do not fulfill high-risk criteria, and are receiving an antibiotic for treatment of LRTI or undifferentiated sepsis. Exclusion Criteria(Adult arm =\> 18 years old): * Age \<18 years old * Pregnancy (current) or breastfeeding * Lung cancer or another malignancy metastatic to the lungs (currently receiving treatment) * Patient previously enrolled and treated…