What Is Hospital Acquired Pneumonia?

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Hospital-acquired pneumonia (HAP), also known as nosocomial pneumonia, is a lower respiratory bacterial infection that occurs 48 hours or more after hospital admission and does not appear due to intubation at the time of admission.

People experience a host of symptoms ranging from fever and chills to shortness of breath and chest pain and are at higher risk of developing severe complications and even death. Infections are also much more likely in older adults and those who have poor health or are immunocompromised.

This article discusses the symptoms, causes, diagnosis, and treatment of hospital-acquired pneumonia.

A person with an IV on their hand lying in a bed

Skaman306 / Getty Images


The first sign of hospital-acquired pneumonia may be a change in mental status, irritability, or confusion, but cases vary widely from person to person. Other common symptoms include:

  • Productive cough (cough with greenish or pus-like phlegm called sputum)
  • Fever
  • Chills
  • General discomfort, uneasiness, or ill feeling (malaise)
  • Loss of appetite
  • Nausea and vomiting
  • Sharp chest pain that worsens with deep breathing or coughing
  • Shortness of breath

Common Causes

HAP is caused by bacteria, especially aerobic (able to grow under an air atmosphere) gram-negative bacilli, such as:

The following risk factors may put you at higher risk of acquiring HAP: 

  • Alcohol abuse
  • Prior history of chest surgery or other major surgery
  • Weak immune system from cancer treatment, certain medicines, or severe wounds
  • Chronic lung disease
  • Older age
  • Are not mentally alert due to medicines or illness
  • Are on a breathing machine


HAP is indistinguishable from other forms of pneumonia, so a diagnosis is usually made based on:

  • A person's symptoms: People with HAP often present with cough, chest pain on deep breathing, shortness of breath, and sputum production.
  • The presence of consolidation or opacities in the lungs: This is found via a chest X-ray or CT scan.

One or more of the following factors also help diagnose HAP:

Bacterial culture is considered the gold standard for confirmation of pneumonia. Cultures can be obtained from:

  • Sputum
  • Nasotracheal suction (using the nasal cavity as a route for the insertion of a suction catheter into the trachea through the larynx)
  • Bronchoscopy
  • Blood cultures

A lower respiratory culture should be obtained before initiating antibiotics; not only is this helpful in diagnosing the exact cause of your HAP, but it also allows your healthcare provider to de-escalate antibiotics and focus on killing the offending pathogen.


If there is suspicion of hospital-acquired pneumonia, your antibiotic treatment will likely be chosen based on your local sensitivity patterns, that is, the likelihood that the bacteria in question will be killed by a given antibiotic based on its responsiveness to treatment and your risk of developing antibiotic resistance.

Antibiotic-resistant organisms—bacteria that have learned to avoid the killing mechanisms of antibiotics—are of growing concern.

Antibiotics can be given by mouth or intravenously depending on your severity. Antibiotics administered in the hospital are more likely to be given via an IV placed in your arm. If you require outpatient antibiotics you will likely receive a prescription for an oral tablet that you can take by mouth.

If the risk of bacterial resistance is low in the hospital, the following antibiotics may be used to treat HAP:

  • Zosyn (piperacillin/tazobactam)
  • Maxipime (cefepime)
  • Levaquin (levofloxacin)
  • Primaxin IV (imipenem/cilastatin)
  • Merrem (meropenem)

If the risk of bacterial resistance is high, vancomycin or linezolid should be added to the treatment regime. At times, “high guns” may need to be used to vanquish pseudomonas infections that are resistant to this regimen. Adding one of the following may be effective:

  • An antipseudomonal cephalosporin (cefepime or ceftazidime)
  • An antipseudomonal carbapenem (imipenem, meropenem)
  • A beta-lactam/beta-lactamase inhibitor (piperacillin/tazobactam)
  • An antipseudomonal fluoroquinolone (ciprofloxacin or levofloxacin)
  • An aminoglycoside (amikacin, gentamicin, tobramycin)


Studies consistently show that people affected with HAP are at increased risk of all cause mortality, sometimes as high as 50%, despite the availability of effective antibiotics.

Even when people survive the primary infections that cause HAP, they are at risk of dying from associated pre-existing health conditions that may have worsened during their recovery from infection. 

Variables associated with increased mortality include:


Hospital-acquired pneumonia (HAP), also known as nosocomial pneumonia, is a lower respiratory bacterial infection that occurs 48 hours or more after hospital admission.

It is most often caused by gram-negative-bacilli bacteria and can occur in anyone, although those who are immunocompromised are at the highest risk.

A Word From Verywell

HAP is often a severe medical complication that healthcare providers take serious precautions to prevent. Still, it may be hard to determine the early signs of HAP, especially when the person affected is already sick, underscoring the importance of watching closely for any small changes that may take place in a loved one's condition.

If you suspect that a friend or a family member has HAP, notify a healthcare provider immediately, as early initiation of broad-spectrum antibiotics has been shown to decrease the likelihood of morbidity and mortality.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Hospital acquired pneumonia management and prevention guidelines.

  2. BMJ Best Practices. Hospital-acquired pneumonia (non COVID-19).

  3. UptoDate. Treatment of hospital-acquired and ventilator-associated pneumonia in adults.

  4. Giuliano KK, Baker D, Quinn B. The epidemiology of nonventilator hospital-acquired pneumonia in the United States. American Journal of Infection Control. 2018;46(3):322-327. doi:10.1016/j.ajic.2017.09.005

By Shamard Charles, MD, MPH
Shamard Charles, MD, MPH is a public health physician and journalist. He has held positions with major news networks like NBC reporting on health policy, public health initiatives, diversity in medicine, and new developments in health care research and medical treatments.