Aspiration pneumonia bacterial infection
|
Pneumonia Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Aspiration pneumonia bacterial infection On the Web |
|
American Roentgen Ray Society Images of Aspiration pneumonia bacterial infection |
|
Risk calculators and risk factors for Aspiration pneumonia bacterial infection |
Editor(s)-in-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-632-7753; Associate Editor(s)-In-Chief: Priyamvada Singh, M.D. [2]
Overview
Aspiration pneumonia caused by bacterial infection is the commonest subtype of aspiration pneumonia. The other subtypes being chemical pneumonia, and airway obstructions.
Causes
- Normal flora of upper airways, gingival cavity or stomach.
- Caused by less virulent bacteria, such as aerobic or microaerophilic streptococci (commonest) and anaerobes (second common cause) such as
Diagnosis
History and symptoms
The manifestation depends on:
- The bacteria involved
- Time since aspiration to diagnosis
- Immune status of the host
Symptoms in aerobic microbes
- Abrupt or Indolent course
- Productive cough
- Fever
- Absence of chills and rigors
- Dyspnea
- Anorexia, weight loss
- Anemia
Lab diagnosis
Sputum culture
- Expectorated sputum is not used as an diagnostic tools as contamination by the normal flora of the mouth and airways is inevitable.
- Specimen obtained via bronchoscopy may be suitable but limited studies are available to prove this.
Symptoms in anaerobic microbes
Clinical features, which are characteristic of aspiration pneumonia involving anaerobic bacteria, include:
- Indolent course
- Presence of risk factors: altered sensorium (anesthesia, alcohol, drug, trauma, dysphagia, dental caries)
- Putrid sputum
- Absence of chills and rigors
Chest X Ray
- Lung abscess
- Empyema
- Involvement of dependent pulmonary lobes i.e., upright position lower lobe, superior segment of lower lobes or posterior segment of upper lobes in recumbent position
Natural History, Complications and Prognosis
- Lung abscess
- Necrotizing pneumonia
- Empyema
- Bronchopleural fistula
Risk factors
- Poor dental hygiene is a risk factor
- Patients with good dental hygiene and edentulous are less predisposed
Treatment
Medical therapy
Antibiotics
- Treatment of choice clindamycin
- Doses 600 mg BID
- Other agents used: Ampicillin-sulbactam (1.5 g or 3 g twice daily), Imipenem (Invanz 500 mg BID), amoxicillin-clavulnate, penicillin + metronidazole.
- Monotherapy with metronidazole is not preferred as high failure rates have been reported. This is because metronidazole is ineffective against some pathogens such as microaerophilic and aerobic streptococci
- Advantage of clindamycin :
- Cheap
- Less incidences of superimposed MRSA