Dr. Griffith joined the faculty of the University of Texas Health Science Center, Tyler in 1985. He is board certified in Internal Medicine and Pulmonary Medicine. He is currently Professor of Medicine and Pulmonary Infectious Disease Division Chief. In addition to the positions at UTHSCT, he is the UT TB Program Director at the Texas Center for Infectious Diseases (TCID) in San Antonio, TX and the Assistant Medical Director for the Heartland National Tuberculosis Center, which is also based at TCID in San Antonio, TX. Since 2002, he has held the William A. and Elizabeth B. Moncrief Distinguished Professorship Chair at UTHSCT.

Dr. Griffith has been involved in patient care and research involving nontuberculous mycobacteria for more than 30 years. He has authored or co-authored more than 200 peer reviewed publications including original research manuscripts, book chapters, reviews, editorials and electronic publications, primarily related to nontuberculous mycobacterial disease. He participated in writing the 1997 American Thoracic Society (ATS) Statement on the Diagnosis and Treatment of Nontuberculous Mycobacterial Disease.He was the principal author for the most recent American Thoracic Society and Infectious Diseases Society of America Guidelines for the Diagnosis, Treatment and Prevention of Nontuberculous Mycobacterial Diseases published in 2007.

Dr. Griffith also serves on the Board of Directors for the Nontuberculous Mycobacteria Information and Research Foundation. Dr. Griffith is a frequent speaker about Nontuberculous Mycobacterial Diseases in national and international fora such as the annual meetings of the American Thoracic Society, American College of Chest Physicians (ACCP), and the European Respiratory Society (ERS).