Tuberculosis Risk Assessment among Hospital Personnel

A recent increase in the rate of tuberculosis among hospital personnel has led to a greater concern about the risk of Mycobacterium tuberculosis transmission in the hospital. A cross-sectional study was conducted to assess the risk of tuberculosis infection among hospital personnel of a governmental hospital in Bangkok by applying hospital tuberculosis control strategies, including administrative control, risk exposure, use of protective barriers when in contact with TB patients, and microbial air quality in the studied wards. Fourteen members of the infection control committee (ICC) and 118 hospital personnel were interviewed regarding the infection control policy and its implementation. The history of TB exposure at work and the use of protective barriers when in contact with TB patients were recorded for the studied hospital personnel. Air samples in the studied wards were collected to investigate bacterial and fungal counts. The results reveal that all the studied ICC members and more than 85% of studied hospital personnel knew the infection control policy and attempted to implement it. However, 35.71, 37.50, 80.90, 93.93, and 88.46% of personnel working in ER, OPD, ICU, female medical ward, and male medical ward, respectively, implemented the TB isolation policy. More than 80% of studied personnel had histories of exposure to TB patients, but only 52.73% (31.57% in OPD to 80.00% in ICU) used the appropriate barriers (N95) when in contact with TB patients. Air samples collected from the studied wards, except ICU, had high bacterial and fungal counts (> 500 cfu/m). These findings show that hospital personnel working in the studied wards, except ICU, were at risk for tuberculosis infection. The hospital ICC should advertise the use of TB standard precautions to hospital personnel and provide a ventilation system for reducing the microbial counts in the air of the studied wards. Correspondence: Pipat Luksamijarulkul, Department of Microbiology, Faculty of Public Health, Mahidol University, 420/1 Ratchawithi Road, Phayathai, Ratchathevi, Bangkok 10400, Thailand. Tel: 66 (0) 2354 8538 E-mail: [email protected] SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 1006 Vol 35 No. 4 December 2004 impaired immune systems (Sepkowitz et al, 1995; Evenson, 1999). A recent increase in the rate of tuberculosis among health care workers, as well as hospital-based outbreaks of multi-drug resistant M. tuberculosis among HIV patients, have led to greater concern about the risk of tuberculosis transmission in health care settings in many countries, including Thailand (Kantor et al,1988; Dooley et al, 1992; Sepkowitz, 1995; Harries et al,1997; Ubolsa-ard and Nakkroun, 1997; WHO, 1999; Chutimanukul et al,1999). The risk may be higher in areas where patients with tuberculosis are cared for before diagnosis or initiation of tuberculosis treatment, where diagnostic or treatment procedures that stimulate coughing are performed, and where there is inadequate ventilation. Many studies report that hospital personnel working in HIV units, internal medicine wards, emergency rooms, medical intensive care units, and outpatient departments have a higher proportion of positive purified protein derivative (PPD) tests than other groups (Kantor et al, 1988; Dooley et al, 1992; Sepkowitz, 1995; Ubolsa-ard and Nakkroun, 1997; WHO, 1999). Strategies for TB infection control in the hospital include administrative control, environmental control, and personal respiratory protection (Blumberg et al, 1995; WHO, 1999). Administrative control reduces hospital personnel and patient exposure, whereas, environmental control reduces the amount of infectious droplets. Personal respiratory protection protects hospital personnel in areas where the number of infectious droplets cannot be adequately reduced by the other controls. This study attempted to apply TB infection control strategies to the prevention of M. tuberculosis infection in hospital personnel working in different wards at a governmental hospital in Bangkok, by using administrative control (administrative policies and their implementation), reduces exposure to TB patients, use of protective barriers when in contact with TB patients, and evaluating microbial air quality on the wards. MATERIALS AND METHODS Study design and study samples A cross-sectional study of 14 infection control committee (ICC) members and 118 hospital personnel in a governmental hospital in Bangkok was conducted between June 2001 and March 2002 to assess the perceptions of infection control policy and its implementation in the hospital, the history of exposure to tuberculosis patients, and the use of protective barriers when in contact with TB patients. In addition, air samples in TB at risk wards, including male and female medical wards, the medical intensive care unit (ICU), emergency room (ER), and out-patient department (OPD), were collected to assess air quality. Study methods and research tools Interviews were by structured questionnaire, which included open-ended and close-ended questions regarding general information, the knowledge of the infection control policy, and its implementation in the hospital, history of exposure to TB patients and the use of protective barriers when in contact with TB patients. The air quality study measured bacterial counts, fungal counts, and Staphylococcus spp counts. The total bacterial count was obtained using Plate Count Agar (PCA) or Tripticase Soy Agar (TSA). The total fungal count was obtained using Sabouraud Dextrose Agar (SDA). Staphylococcus spp was cultivated in Mannitol Salt Agar. Air samples in the studied wards were collected using the Anderson N6 Viable Particle Sampler with a fixed air flow rate of 28.3 liter/minute. The air was collected for 3 minutes. Triplicate air samples were collected from each area. Air flow direction was measured using a smoke tube. After incubation of the air samples, the total counts of culturable bacteria, fungi or Staphylococcus spp (cfu/m) were calculated with the formula: Microbial count (cfu/m) = (Total colony x 10)/ air flow rate x time Interpretation of microbial air quality If the total bacterial or fungal count was more than 500 cfu/m, it indicated poor ventilation or unhygienic conditions following the American Conference of Governmental Industrial Hygienist (ACGIH) committee recommendations (Seitz, 1989). There were no guidelines for Staphylococcus spp interpretation.