Snapshot A 36-year-old woman is brought to the emergency department for seizures that began 10 minutes prior to presentation with no clear precipitating cause. On physical exam, the patient is having a generalized tonic-clonic seizure. She is administered lorazepam and a second intravenous line is obtained for fosphenytoin, but the seizures do not abort. The patient is intubated, given propofol, and is admitted to the medical intensive care unit. On hospital day 3, the patient is difficult to wean from anticonvulsants and remains intubated. Her temperature is 101°F (38.9°C), blood pressure is 138/99 mmHg, pulse is 101/min, and respirations are 19/min with an oxygen saturation of 89% on room air. Physical examination is notable for crackles on the right anterior chest and a chest radiograph demonstrates a right lung lobar consolidation. Blood and sputum cultures are obtained and she is started on empiric antibiotic treatment, vancomycin and piperacillin-tazobactam, while cultures and sensitivities return. Introduction Definition hospital-acquired pneumonia (nosocomial pneumonia) pulmonary infection that occurs ≥ 48 hours after admission to the hospital ventilator-acquired pneumonia pulmonary infection that develops ≥ 48 hours after endotracheal intubation Microbiology common pathogens include aerobic gram-negative bacilli Escherichia coli Klebsiella pneumoniae Enterobacter spp Pseudomonas aeruginosa Acinetobacter spp gram-positive cocci Staphylococcus aureus including methicillin-resistant S. aureus (MRSA) Streptococcus spp risk factors for multidrug-resistant organisms prolonged hospitalization recent exposure to antibiotics Epidemiology Incidence one of the most common hospital-acquired infections in the hospital setting Risk factors mechanical ventilation increasing age immunocompromised chronic lung disease Pathogenesis Virulent microorganisms enter the lower respiratory tract, resulting in an immunse response to the pathogen primary route of infection of the lungs is via microaspiration of organisms colonized in the oropharyngeal and gastrointestinal tract Presentation Symptoms productive or non-productive cough dyspnea pleuritic chest pain fatigue and malaise Physical exam fever tachypnea increased work of breathing pulmonary auscultation rales/crackles rhonchi tactile fremitus egophony dullness to percussion Imaging Chest radiograph findings lobar consolidation pleural effusion cavitary lesions Studies Making the diagnosis new lung infiltrate noted on chest imaging and fever purulent sputum leukocytosis decline in oxygenation Sputum Gram stain and culture Blood cultures acquire before administering antibiotics Other studies depend on clinical suspicion urine Legionella antigen testing induced sputum acid-fast bacillus stain and mycobacterial culture for tuberculosis direct fluorescent-antibody or PCR testing of a nasopharyngeal swab or sputum for viral causes Bronchoscopy is considered in critically ill patients patients who fail to respond to therapy chronic pneumonia immunosuppressed Differential COPD exacerbation differentiating factor patient has a history of COPD Community-aquired pneumonia differentiating factor patients develop pneumonia outside the hospital and healthcare setting Treatment Medical empiric antibiotic treatment indication initial medical therapy of choice administered after cultures are obtained approach antibiotic choice should cover Staphylococcus aureus Pseudomonas aeruginosa other gram-negative bacilli medications vancomycin or linezolid piperacillin-tazobactam cefepime levofloxacin imipenem Complications Respiratory failure Sepsis Septic shock Empyema requires drainage with a chest tube in addition to antibiotics Prognosis Associated with high mortality rates without antibiotics