RISK FACTORS: Prone to aspiration of oral flora, Periodontal disease,(gingivitis), dental abscess, dental surgery, Substance abuse, alcoholism, Epilepsy, CVA with oropharyngeal dysfunction, Sinusitis, General anesthetic with surgery
RISK FACTORS
. Prone to aspiration of oral flora
. Periodontal disease (gingivitis), dental abscess, dental surgery
. Substance abuse, alcoholism
. Epilepsy
. CVA with oropharyngeal dysfunction
. Sinusitis
. General anesthetic with surgery
. Dysphagia
. Tracheal/nasogastric tube
. Severe gastroesophageal reflux disease
. Cerebral palsy
. Large bacterial burden
. Necrotizing pneumonia
. Bacteremia
. Septic embolism (especially from endocarditis)
Medical Care: Treatment of lung abscess is guided by the available microbiology and knowledge of the underlying or associated conditions.
" Antibiotic therapy
o Standard treatment of an anaerobic lung infection is clindamycin (600 mg IV q8h followed by 150-300 mg PO qid).
o This regimen has been shown to be superior over parenteral penicillin in published trials. Several anaerobes may produce beta-lactamase (eg, various species of Bacteroides and Fusobacterium) and therefore develop resistance to penicillin.
o Although metronidazole is an effective drug against anaerobic bacteria, the experience with metronidazole in treating lung abscess has been rather disappointing because these infections are generally polymicrobial. A failure rate of 50% has been reported.
o In hospitalized patients who have aspirated and developed a lung abscess, antibiotic therapy should include coverage against S aureus and Enterobacter and Pseudomonas species.
o Cefoxitin is a second-generation cephalosporin that has gram-positive, gram-negative, and anaerobic coverage. This agent may be used when a polymicrobial infection is suspected as cause of lung abscess.
o In a prospective open, randomized, trial to compare the safety and clinical and bacteriologic efficacy of ampicillin plus sulbactam versus clindamycin with or without cephalosporin, 95 patients with pulmonary infection following aspiration were included. In patients treated with ampicillin plus sulbactam, the clinical response was 73.0% at the end of therapy and 67.5% 7-14 days after therapy. For clindamycin, the rates were 66.7% and 63.5%, respectively. Both therapies were well tolerated and proved equally effective in the treatment of aspiration pneumonia and lung abscess (Allewelt, 2004).
" Duration of therapy
o Although the duration of therapy is not well established, most clinicians prescribe antibiotic therapy generally for 4-6 weeks.
o Current recommendations are that antibiotic treatment should be continued until the chest radiograph has shown either the resolution of lung abscess or the presence of a small stable lesion.
o The rationale for extended treatment maintains that risk of relapse exists with a shorter antibiotic regimen.
" Response to therapy
o Patients with lung abscesses usually show clinical improvement, with improvement of fever, within 3-4 days after initiating the antibiotic therapy. Defervescence is expected in 7-10 days. Persistent fever beyond this time indicates therapeutic failure, and these patients should undergo further diagnostic studies to determine the cause of failure.
o Considerations in patients with poor response to antibiotic therapy include bronchial obstruction with a foreign body or neoplasm or infection with a resistant bacteria, mycobacteria, or fungi.
o Large cavity size (ie, >6 cm in diameter) usually requires prolonged therapy. Because empyema with an air-fluid level could be mistaken for parenchymal abscess, a CT scan may be used to differentiate this process from lung abscess.
o A nonbacterial cause of cavitary lung disease may be present, such as lung infarction, cavitating neoplasm, and vasculitis. The infection of a preexisting sequestration, cyst, or bulla may be the cause of delayed response to antibiotics.
Surgical Care: Surgery is very rarely required for patients with uncomplicated lung abscesses. The usual indications for surgery are failure to respond to medical management, suspected neoplasm, or congenital lung malformation. The surgical procedure performed is either lobectomy or pneumonectomy.
When conventional therapy fails, either percutaneous catheter drainage or surgical resection is usually considered. Endoscopic lung abscess drainage was considered if an airway connection to the cavity could be demonstrated. Success of this treatment represents an additional option other than percutaneous catheter drainage or surgical resection (Herth, 2005).
DRUG(S) OF CHOICE Antibiotics according to culture and sensitivity results. For presumed anaerobes,
clindamycin 600 mg every 6 hours IV, followed by 300 mg every 6 hours orally for 4 weeks.
ALTERNATIVE DRUGS
β’ Standard therapy has historically been penicillin G 1-2 million units IV every 4 hours until improved, followed
by 1.2 million units (750 mg) orally every 6 hours for 3-4 weeks.
β’ Cefoxitin 2.0 gm IV q 8 hours
β’ Piperacillin-tazobactam 3.375 gm IV q 6 hours
β’ Ticarcillin-clavulanate 3.1 gm IV q 6 hours
β’ Metronidazole has not proven as effective as clindamycin, but is often recommended for use as an adjunctive therapy (500 mg IV q 6 hours)
β’ Full course of therapy may be needed for 8 weeks
PATIENT MONITORING Serial x-rays until resolution of cavity
PREVENTION/AVOIDANCE Treat predisposing diseases; aspiration precautions; treatment of periodontal diseases
POSSIBLE COMPLICATIONS
. Extension
. Empyema
. Massive hemoptysis
. Pneumothorax
. Brain abscess
EXPECTED COURSE/PROGNOSIS
. Clinical improvement with decrease in fever expected in 3-4 days after starting antibiotics
. Defervescence (resolution of fever) expected in 7-10 days
. Overall mortality 10-15%
. Prognosis depends on the underlying disease or immunosuppression
. Patients with primary abscess (otherwise healthy, typical aspiration) have cure rate of 90-95%
. Patients with secondary abscess (underlying neoplasm, obstruction, HIV) have 75% mortality
. Certain factors tend to have worse prognosis:
. Large size of abscess (> 6 cm)
. Anatomical obstruction
. Right lower lobe location
. Certain bacteriologic species - more violent (staph aureus, Klebsiella, pseudomonas)