Dr. K is Jeffrey D. Klausner, MD, MPH, a board certified internist and infectious disease specialist. He attended Cornell University Medical College, completed his residency at NYU-Bellevue Hospital Center, earned a Master's in Public Health at Harvard University and worked as an Epidemic Intelligence Service Officer at the Centers for Disease Control and Prevention.

Currently, he is a deputy health officer and director of the STD Prevention and Control Services Section at the San Francisco Department of Public Health which oversees City Clinic, San Francisco's low-cost and confidential STD clinic and supports the St. James Infirmary and MAGNET. He often practices at City Clinic during drop-in services.

He also has an AIDS practice at UCSF-San Francisco General Hospital, where he is an attending physician. He is an Associate Clinical Professor who teaches AIDS, medicine and infectious diseases at the UCSF School of Medicine. He is also the Co-Director of San Mateo San Francisco Peninsula HIV/AIDS Research Center. He is an author of over 120 scientific articles and book chapters on STDs, HIV and prevention and a well-known expert in HIV prevention and STDs in men who have sex with men, gay men and young adults. Finally, he is the Senior Editor of Lange Current Diagnosis & Treatment of Sexually Transmitted Diseases.

In 2002 he was recipient of the American STD Association's young investigator award and that same year received the San Francisco Suicide Prevention's community service award. In 2006 he received the UCSF Association of Clinical Faculty's special recognition award for his contributions in teaching.