The differential should include other causes of hemolysis, such as that found in non-immune hemolytic anemia including intrinsic red cell defects, hemolysis due to extrinsic factors (ie trugs or toxins) as well as mechanical damage hemolytic anemia as found in DIC and HUS.
The best initial antibiotic choice is thought to be a macrolide. Macrolides provide the best coverage for the most likely organisms in community-acquired bacterial pneumonia (CAP). Macrolides have effective coverage for gram-positive, Legionella, and Mycoplasma organisms. Azithromycin administered intravenously is an alternative to intravenous erythromycin.
Several classes of antibiotics are effective against atypical pathogens. However, because C. pneumoniae and Legionella species are intracellular organisms and M. pneumoniae lacks a cell wall, beta-lactams are not effective. Erythromycin and, in some cases, tetracycline have been traditional choices for the treatment of pneumonia caused by atypical pathogens. There are few (if any) clinical trials demonstrating the efficacy of erythromycin for Legionella infection.