1-Severity of the disease: Patient needs hospitalization or not
2-Type of pneumonia: Is it community acquired or Hospital Acquired.
Severity of the disease
Mild pneumonia can be treated without admitting the patient, however if the disease is sever the patient has to be admitted to undergo treatment. There are major determinants of severity. Read signs & symptoms of pneumonia to understand better.
Degree of hypoxia (Deprivation of oxygen supply)- If the partial pressure of oxygen is less than 60 mm of HG, oxygen saturation is below 94 percent on room air, respiratory rate above 30/minute, confusion or disorientation, uremia (building up of nitrogenous waste in the body due to renal failure caused by hypoxia in this case).
Hypotension- Systolic below 90 and diastolic below 60 mm of HG
Other markers of severity:
High fever, hypothermia, leucopenia (decrease in WBC) , usually less than 4000/ cubic mm, rapid pulse >125/min, hyponatremia (decrease in sodium content of the body), dehydration.
Patients with serious underlying illness are also needed to be hospitalized. These co-morbid conditions include cancer, renal disease, liver disease or chronic lung disease.
Treatment of Community Acquired Pneumonia:
Antibiotics are used to treat pneumonia. The specific causative germ or bacteria is not known at the time of the start of the treatment, so treatment is started with emperical therapy.
If the there is no need to admit the patient the antibiotic of choice for “Outpatient Community Acquired Pneumonia” is Macrolides (Azithromycin or Clarithromycin)
New Flouroquinolones (levofloxacin or gatifloxacin)can also be used and are generally second line drug of choice.
Macrolides or New flouroquinolones
Since mild cases of community acquired pneumonia are usually mycoplasma and chlamydia pneumoniae we do not use 2nd and 3rd gen cephalosporis as they do not cover all the atypical agents.
Hospitalized patients are usually treated with new fluoroquinolones or 2nd or 3rd generation cephalosporins (cefuroxime or ceftriaxone) combined with a macrolide or doxcycline
New Fluoroquinolones or 2nd-3rd gen cephalosporins +Macrolide / Doxycycline
Treatment of Hospital Acquired Pneumonia
Some patients might develop pneumonia while there stay in hospital usually after 48 hours of stay. Main causes of hospital aquired pneumonia are
1-Gram negative bacilli (Pseudomonas, Klebsiella, E.coli)
2-Gram positive bacilli (Methicillin resistant Staph Aureus)- MRSA
The empirical therapy is done usually with 3rd generation cephalosporins with anipseudomonal activity (Ceftazidime or cefotaxime) or carbepenems (imipenem) or beta lactam/beta lactamase inhibitaor comnination (piperacillin/tazobactam) with coverage of MRSA by Vancomycin or linezolid.
3gen cephalosporin/carbepenem/b-lactam,lactamase inhibitor + Vancomycin
Aminoglycosides like amikacin, gentamycin is added to prevent drug resistance, synergistic effect and to make better gram negative coverage.
Once the result of sputum culture or bronchoalveolar lavage or pleural fluid culture is out, we can adjust the antibiotics accordingly. Read diagnosing pneumonia for better undestanding.
Special bugs need special antibiotics
1-Peumocystis: Trimethoprim Sulfamethoxazole (TMP/SMZ). Steroids should be used if the infection is severe (arterial PO2 is less than 70mmof HG or A-a gradient is greater than 35 mm of HG). If patient is allergic to TMP/SMZ, I.V pentamidine or atovaquone can be used. Dapsone or atovaquone can be used prophylactically.
2- Coxiella Brunetti (Q-Fever)- usually treated with doxycycline or erythromycin as an alternative.
3-Coccidioidomycoses- no need for treatment for primary pulmonary disease. Treatment is required only for disseminated disease or if the patient is immunocompromised. Life threatening disease is treated with amphotericin while milder form is treated with fluconazole or itraconazole.
Those patients who are at risk for pneumonia should receive pneumococcal vaccine.