What are the risk factors for developing hospital-acquired pneumonia (HAP)?

Updated: Apr 15, 2021
  • Author: Kartika Shetty, MD, FACP; Chief Editor: John L Brusch, MD, FACP  more...
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The stomach appears to be an important reservoir of gram-negative bacilli that can ascend and colonize the respiratory tract. A prospective observational study found that patients who used acid-suppressive medications were more likely to develop hospital­ acquired pneumonia (HAP) than were patients who did not (5% vs 2%). Further evaluation by drug class showed that the risk for pneumonia was significantly increased with proton pump inhibitors, but not with histamine 2-blocking agents. [8]

Endotracheal intubation is an independent risk factor with multiple associated factors such as:  

  • Micro aspiration around endotracheal tube
  • Endotracheal intubation
  • Prolonged duration of ventilation
  • Abnormal swallowing function
  • Secretions pooled above endotracheal tube

The endotracheal tube, which acts as a foreign body, the pooling of secretions and the resultant need for suctioning can damage the tracheal mucosa. This can further facilitate tracheal colonization. Additionally, pathogenic bacteria can form a glycocalyx biofilm on the tube’s surface that protects them from both antibiotics and host defenses. This can become a contributing factor to recurrence of infection and treatment failure as well. 

Other risk factors include prior antibiotic use, cross contamination with other patients on the unit and malnutrition.

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