MKC-0826 is a recently developed investigational antibiotic drug that has been shown in laboratory tests to have a strong inhibitory effect on the growth of bacteria. Ceftriaxone sodium, a marketed drug has been approved by the Food and Drug Administration (FDA) for the treatment of complicated lower respiratory infections, including pneumonia. The purpose of this study is to determine whether MK-0826 is equivalent to ceftriaxone (an established cephalosporin with a prolonged serum half-life) for the treatment of community acquired pneumonia in adults with a positive Gram stain. The primary goal is comparison of clinical efficacy, secondary and tertiary goals are comparisons of safety and microbiologic effects.