Antibiotic therapy is empirical, including both normal and atypical organisms. Outpatient therapy of immunocompetent adult patients with doxycycline, a fluoroquinolone with improved action against Streptococcus pneumoniae, or a macrolide is suitable. If the patient's condition requires hospitalization, intravenous antibiotic therapy should be initiated as soon as possible. An aminoglycoside may be added if methicillin-resistant Staphylococcus aureus (MRSA) is suspected. Vancomycin may be required in severe cases or when methicillin resistance is confirmed. Atypicals are common causes of bacterial infections that are not covered by standard antibiotics. However, many atypicals can be treated with appropriate antibiotics. The choice of drug will depend on what other medications the patient is taking and the severity of the infection. It is important to choose an antibiotic that is effective against atypicals while causing few side effects. Tetracyclines: doxycycline, minocycline Macrolides: erythromycin, azithromycin, clarithromycin