Hospital-acquired pneumonia overview
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Differentiating Hospital-Acquired Pneumonia from other Diseases |
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Diagnosis |
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Editor(s)-in-Chief: C. Michael Gibson, M.S., M.D. ; Philip Marcus, M.D., M.P.H.
Overview
American Thoracic Society (ATS) and the Infectious Disease Society of America (IDSA) definitions of Hospital acquired pneumonia, ventilator-associated pneumonia, and health care associated pneumonia [1]
Hospital-Acquired Pneumonia (HAP)
HAP is defined as pneumonia that occurs 48 hours or more after admission, which was not incubating at the time of admission
Ventilator-associated pneumonia (VAP)
VAP refers to pneumonia that arises more than 48–72 hours after endotracheal intubation. Some patients may require intubation after developing severe HAP and should be managed similar to patients with VAP.
Healthcare-Associated Pneumonia (HCAP)
HCAP includes any patient who was hospitalized in an acute care hospital for two or more days within 90 days of the infection; resided in a nursing home or long-term care facility; received recent intravenous antibiotic therapy, chemotherapy, or wound care within the past 30 days of the current infection; or attended a hospital or hemodialysis clinic. }}
Pathophysiology
Most nosocomial respiratory infections are caused by so-called skorvatch microaspiration of upper airway secretions, through inapparent aspiration, into the lower respiratory tract. Also, "macroaspirations" of esophageal or gastric material is known to result in HAP. Since it results from aspiration either type is called aspiration pneumonia. Although gram-negative bacilli are a common cause they are rarely found in the respiratory tract of people without pneumonia, which has led to speculation of the mouth and throat as origin of the infection.
Causes
The majority of cases related to various gram-negative bacilli (52%) and S. aureus (19%). Others are Haemophilusspp. (5%). In the ICU results were S. aureus(17.4%), P. aeruginosa (17.4%), Klebsiella pneumoniae andEnterobacter spp. (18.1%), and Haemophilus influenzae (4.9%). Viruses -influenza and respiratory syncytial virus and, in the immunocompromised host, cytomegalovirus- cause 10-20% of infections.
Differentiating Hospital-Acquired Pneumonia From Other Diseases
Epidemiology and Demographics
Pneumonia is a common illness in all parts of the world. It is a major cause of death among all age groups. Mortality from pneumonia generally decreases with age until late adulthood. Elderly individuals, however, are at particular risk for pneumonia and associated mortality. More cases of pneumonia occur during the winter months than during other times of the year. Pneumonia occurs more commonly in males than females, and more often in Blacks than Caucasians. Individuals with underlying illnesses such as Alzheimer's disease, cystic fibrosis, emphysema, tobacco smoking,alcoholism, or immune system problems are at increased risk for pneumonia.[2] These individuals are also more likely to have repeated episodes of pneumonia. People who are hospitalized for any reason are also at high risk for pneumonia. Following urinary tract infections, this is the second common cause of nosocomial infections, and its prevalence is 15-20% of the total number
Diagnosis
Diagnostic Criteria
In hospitalised patient who develop respiratory symptoms and fever one should consider the diagnosis. The likelyhood increases when upon investigation symptoms are found of respiratory insufficiency, purulent secretions, newly developed infiltrate on the chest X-Ray, and increasing leucocyte count. If pneumonia is suspected material from sputum or tracheal aspirates are sent to the microbiology department for cultures. In case ofpleural effusion thoracentesis is performed for examination of pleural fluid. In suspected ventilator-associated pneumonia it has been suggested that bronchoscopy(BAL) is necessary because of the known risks surrounding clinical diagnoses.
History and Symptoms
People with pneumonia often have a productive cough, fevershaking chills, Shortness of breath, pleuritic chest pain, cough up blood, headaches, sweaty, and clammy skin. Other possible symptoms are loss of appetite, fatigue, blueness of the skin, nausea,vomiting, mood swings, andjoint pains or muscle aches. In elderly people manifestations of pneumonia may not be typical. They may develop a new or worsening confusion or may experience unsteadiness, leading to falls. Infants with pneumonia may have many of the symptoms above, but in many cases they are simply sleepy or have a decreased appetite.
Laboratory Tests
Current guidelines recommend a combination of chest Xray,laboratory data as well as clinical judgment in diagnosis and management of community acquired pneumonia.
Major points and Recommendations for laboratory tests in adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia [1]
- Arterial oxygenation saturation should be measured in all patients to determine the need for supplementaloxygen. Arterial blood gas should be determined if concern exists regarding either metabolic or respiratory acidosis, and this test generally is needed to manage patients who require mechanical ventilation. These results, along with other laboratory studies (complete blood count, serum electrolytes, renal and liver function), can point to the presence of multiple organ dysfunction and thus help define the severity of illness (Level II).
- All patients with suspected VAP should have blood cultures collected, recognizing that a positive result can indicate the presence of either pneumonia or extrapulmonary infection (Level II).
- A diagnostic thoracentesis to rule out a complicating empyema or parapneumonic effusion should be performed if the patient has a large pleural effusion or if the patient with a pleural effusion appears toxic (Level III).
- Samples of lower respiratory tract secretions should be obtained from all patients with suspected HAP, and should be collected before antibiotic changes. Samples can include an endotracheal aspirate, bronchoalveolar lavage sample, or protected specimen brush sample (Level II)
For Level of evidence and classes click here.
Major points and Recommendations for Chest X Ray of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia [1]
All patients should have a chest radiograph, preferably posteroanterior and lateral if not intubated, as portable chest radiographs have limited accuracy. The radiograph can help to define the severity of pneumonia (multilobar or not) and the presence of complications, such as effusions or cavitation (Level II)
For Level of evidence and classes click here.
Treatment
Medical Therapy
Methicillin-resistant staphylococcus aureus is a common isolate in the patients with Hospital-acquired pneumonia. The treatment options commonly used are vancomycin, linezolid, and clindamycin. Linezolid may be preferred in patients with renal insufficiency as the nephrotoxicity with Linezolid is less compared to vancomycin. Additionally, in patients with vancomycin MIC ≥ 2mcg/mL linezolid is preferred. Linezolid resistance and failure are rare.
References
- ↑ 1.0 1.1 1.2 "Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia". American Journal of Respiratory and Critical Care Medicine. 171 (4): 388–416. 2005. doi:10.1164/rccm.200405-644ST. PMID 15699079. Retrieved 2012-09-12. Unknown parameter
|month=ignored (help) - ↑ Almirall J, Bolibar I, Balanzo X, Gonzalez CA. Risk factors for community-acquired pneumonia in adults: A population-based case-control study. Eur Respir J. 1999;13:349. PMID 10065680