The Pneumonia Patient Outcome Research Team developed useful criteria called the pneumonia severity index for assessing pneumonia severity; however, that index proved to be complex and difficult to use. A simpler index called the CURB-65 (confusion, urea nitrogen, respiratory rate, blood pressure, age 65 years or older) has been shown to have sensitivity and specificity nearly equal to that of the pneumonia severity index. Both indexes can be used to guide decisions on admission to a hospital ward or intensive care unit. As shown in Figure 4.5, patients with a score of 0 or 1 can be treated as outpatients; those with a score of 2 or more warrant hospitalization. A patient with a score of 4 to 5 generally requires placement in an intensive care unit.
Empiric Treatment
The mainstay of treatment is administration of antibiotics. Antibiotic treatment should not be delayed because of difficulties with sputum collection. Therapy should be started within 4 hours of diagnosis.
Delays beyond this period have been associated with increased mortality.
In patients requiring hospitalization for acute community-acquired pneumonia, cefotaxime or ceftriaxone (covers S. pneumoniae, H. influnezae, S. aureus, Klebsiella spp, some gram-negative organisms, and aerobic mouth flora), combined with an advanced macrolide [azithromycin or clarithromycin (covers Legionella, Mycoplasma, Chlamydid)] is recommended for empiric therapy. If aspiration pneumonia is suspected, metronidazole can be added.
In ambulatory patients, either a macrolide in the form of azithromycin or clarithromycin, or a respiratory fluoroquinolone (gatifloxacin, moxifloxacin, or levofloxacin) possessing good gram-positive activity is considered efficacious. Concerns have been raised about the development of resistance to fluoroquinolones, and many experts recommend that this class of antibiotics be reserved for older patients with underlying disease. These patients are not only exposed to the standard causes of community-acquired pneumonia, they also experience an increased incidence of gram-negative bacilli that will be covered by those agents.
The appropriate duration of treatment has not been systematically studied. For S. pneumoniae, patients are generally treated for 72 hours after they become afebrile. For infections with bacteria that cause necrosis of lung (S. aureus, Klebsiella, and anaerobes), therapy should probably be continued for more than 2 weeks. Treatment for 2 weeks is generally recommended for Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella in the immunocompetent patient. Patients on intravenous antibiotics can generally be switched to oral antibiotics when their clinical condition is improving, they are hemodynamically stable, their gastrointestinal tract is functioning normally, and they are capable of taking medications by mouth. In many cases, those criteria are met within 3 days. When possible, the oral antibiotic should be of the same antibiotic class as the intravenous preparation. If staying within the class is not possible, then the oral agent should have a spectrum of activity similar to that of the intravenous agent.
Response to treatment can be assessed by monitoring temperature, respiratory rate, PaO2 and oxygen saturation, peripheral white blood cell count, and frequency of cough. The changes seen on OCR often persist for several weeks despite clinical improvement. Although OCR is not helpful for assessing improvement, conventional films can be combined with pulmonary computed tomography scan to assess the development of complications such as pneumothorax, cavitation, empyema, and adult respiratory distress syndrome (adult respiratory distress syndrome), and to document continued progression of infiltrates despite therapy.
Table. Empiric Treatment of Pneumonia, Infectious Diseases Society of America, 2003
| Disease characteristics | Drug | Dose | Comments | ||||
| Community-acquired pneumonia | |||||||
| No comorbidity
No previous antibiotics Outpatient |
Clarithromycin3
or azithromycin3 or erythromycin or doxycycline |
500 mg POq12h
500 mg PO,followed by 250 mg PO q24h 500 mg q6h 100mg POq12h |
Low serum levels,
high levels in macrophages, preferred for Haemophilus influenzae Gastrointestinal toxicity is common Bacteriostatic agent |
||||
| No comorbidity Previous antibiotics, or nursing home resident | Respiratory
fluoroquinolone: gatifloxacin or levofloxacin or moxifloxacin Advanced macrolide, plus |
400 mg PO q24h 500 mg PO q24h
400 mg PO q24h Doses as above |
Levofloxacin-resistant Streptococcus pneumoniae reported in Canada | ||||
| p-lactam antibiotic:
cefuroxime axetil or cefpodoxime or cefprozil or amoxicillin-clavulanate |
500 mg POq12h 400 mg POq12h 500 mg POq12h 2gPOq12h | If aspiration suspected, amoxicillin or amoxicillin-clavulanate recommended. | |||||
| Comorbidity
(congestive heart failure,COPD,DM, cancer, renal disease) Inpatient, medical ward No recent antibiotics |
Advanced macrolide | Doses as above | |||||
| Respiratory fluoroquinolone | Doses as above | ||||||
| Respiratory fluoroquinolone | Doses as above | ||||||
| Clarithromycin
or azithromycin, plus ceftriaxone or cefotaxime |
Dose PO as above 500 mg IV q24h
1 g IV or IM q24h 1 g IV q8h |
||||||
| Inpatient, medical ward | Advanced macrolide,
plus β-lactam antibiotic (preferred) or respiratory fluoroquinolone |
Doses as above | Regimen depends on the previous antibiotic | ||||
| Recent antibiotics | Doses as above | ||||||
| Inpatient, ICU Pseudomonas not an issue | IV p-lactam antibiotic,
plus advanced macrolide or respiratory fluoroquinolone |
Doses as above | |||||
| Inpatient, ICU Pseudomonas an issue | Piperacillin-tazobactam
or imipenem or meropenem or cefepime |
4 g/0.5 g IV q6h 0.5-1 g IV q6h 1 g IV q8h 1 -2 g IV q8h | |||||
| Aspiration pneumonia | |||||||
| Community
In hospital |
Penicillin G Clindamycin | 2X 106UIVq4h 600 mg IV q8h | Covers usual mouth flora Slightly more effective than penicillin for lung abscess | ||||
| Ceftriaxone
plus metronidazole |
1 g IV q24h 500 mg IV q8h | ||||||
| Respiratory fluoroquinolone plus metronidazole | Doses as above 500 mg IV q8h | ||||||
| Piperacillin-tazobactam | 3g/0.375glVq6h | Regimen used by the author | |||||
| ticarcillin-clavulanate | 3.1 g IVq4-6h | Requires a large fluid load | |||||
Outcome
In the United States, 45,000 deaths are attributed to pneumonia annually. In hospitalized patients, overall mortality ranges from 2% to 30%. Mortality from pneumonia and influenza is particularly high in individuals over the age of 65 years, causing 150 to 250 deaths per 100,000 population annually. Mortality is also higher in individuals with underlying diseases. Five comorbid illnesses have been identified that result in statistically significant increases in mortality:
- Neoplastic disease
- Cerebrovascular disease
- Liver disease
- Renal disease
- Congestive heart failure