From: Efficacy of Control Measures in Preventing Nosocomial Transmission of Multidrug-Resistant Tuberculosis to Patients and Health Care Workers Ann Intern Med. 1995;122(2):90-95. doi:10.7326/0003-4819-122-2-199501150-00002 Figure Legend: Distribution of patients with multidrug-resistant tuberculosis by date of first positive culture.The numbers 1 to 4 with arrows indicate the dates of introduction of 1) improved patient isolation, expanded criteria for isolation of patients (June to July 1991), and molded surgical masks (July 1991); 2) improved laboratory services (15 July 1991); 3) acid-fast bacilli isolation rooms on wards with negative pressure systems (September 1991); and 4) negative-pressure chambers for aerosolized pentamidine administration and sputum induction (October 1991). The months are abbreviated using the first letter of the month. Date of download: 10/27/2017 Copyright © American College of Physicians. All rights reserved.