The widespread availability of antimicrobial chemotherapeutics over the last half of the twentieth century has offered dramatic increases in life expectancy. Unfortunately, many pathogenic agents are exhibiting ever increasing resistance to many frontline antibiotics. New chemotherapeutic agents are urgently needed to combat this threat; this work seeks to illustrate applications in which mass spectrometric techniques may be applied to the investigation of novel, small molecule chemotherapeutics for the treatment of bacterial infections. Chapter 1 contains an introduction to mass spectrometry, as well as an overview of relevant chromatographic techniques. Chapter 2 introduces the bacterium F tularensis and M ulcerans and details the MS based investigation of their secreted virulence factors. Chapter 3 introduces a human pathogen of particular concern, M tuberculosis, and contains a detailed reporting on the MS based investigation of internally synthesized compounds for the treatment of latent Tb. vii TABLE OF CONTENTS CHAPTER 1. INTRODUCTION TO MASS SPECTROMETERY .