pulmonary disorders
Ventilator Associated Pneumonia
Etiology of Ventilator Associated Pneumonia
The most common cause of ventilator-associated pneumonia is microaspiration of bacteria that colonize the oropharynx and upper airways in seriously ill patients. Endotracheal intubation is the major risk factor for ventilator-associated pneumonia. Endotracheal intubation breaches airway defenses, impairs cough and mucociliary clearance, and facilitates microaspiration of bacteria-laden secretions that pool above the inflated endotracheal tube cuff. In addition, bacteria form a biofilm on and within the endotracheal tube that protects them from antibiotics and host defenses. The highest risk of VAP occurs during the first 10 days after intubation. Ventilator-associated pneumonia occurs in 9 to 27% of mechanically ventilated patients. Pathogens and antibiotic resistance patterns vary significantly among institutions and can vary within institutions over short periods (eg, month to month). Local antibiograms at the institutional level that are updated on a regular basis are essential in determining appropriate empiric antibiotic therapy. In general, the most important pathogens are Pseudomonas aeruginosa Methicillin-sensitiveStaphylococcus aureus Methicillin-resistantS. aureus(MRSA) Other important pathogens include enteric gram-negative bacteria (mainlyEnterobacterspecies,Klebsiella pneumoniae,Escherichia coli,Serratia marcescens,Proteusspecies, andAcinetobacterspecies). Methicillin-sensitiveS. aureus,Streptococcus pneumoniae, andHaemophilus influenzaeare most commonly implicated when pneumonia develops within 4 to 7 days of hospitalization, whereasP. aeruginosa, MRSA, and enteric gram-negative organisms become more common with increasing duration of intubation or hospitalization. infection in VAP ( Etiology reference ). Infection with a resistant organism markedly increases mortality and morbidity. Other risk factors for antibiotic-resistant organisms specific to VAP include Septic shock at time of VAP Acute respiratory distress syndrome (ARDS) preceding VAP Hospitalization for ≥ 5 days prior to the occurrence of VAP Acute renal replacement therapy prior to VAP onset infections. Chronic suppurative lung diseases such as Cystic Fibrosis and 1.Kalil AC, Metersky ML, Klompas M, et al: Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society.Clin Infect Dis63(5):e61–111, 2016. 