This document provides guidelines for the laboratory identification and antimicrobial susceptibility testing of major bacterial pathogens. It describes methods for confirming the identification of Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, Neisseria gonorrhoeae, Salmonella Typhi, Shigella, and Vibrio cholerae. It also provides standardized protocols for antimicrobial susceptibility testing of these pathogens and discusses epidemiological data needed for treatment decisions. The document was created by the Centers for Disease Control and Prevention in cooperation with the World Health Organization to assist reference laboratories in developing countries.