Evaluation of a Western Blot Test as a Potential Screening Tool for Occupational Exposure to Mycobacterium tuberculosis in Health Care Workers

Abstract

Health care workers (HCWs) have a higher than average risk for contracting Mycobacterium tuberculosis (MTB) infection and tuberculosis (TB). No markers of MTB-exposure are available, and TB risk assessment is performed by tuberculin screening, identifying individuals with acquired MTB infection. This study evaluated a western blot (WB) anti-M. bovis A60 complex antibody as a MTB-exposure marker. WB reactivity was evaluated on 127 exposed and 28 non-exposed HCWs from four divisions of the Policlinico Hospital of Modena, and 140 non-exposed bacille Calmette-Guérin-vaccinated controls. Excess of occupational TB risk according to the Occupational Safety and Health Administration (OSHA) was calculated in each division. WB-positivity (%) was: (1) significantly higher in exposed HCWs compared with non-exposed (72% vs 25%, P < 0.00001), (2) highly related (r = 0.99) to OSHA risk excess in all divisions, (3) higher than non-exposed in HCWs with short (< 5 years) MTB-exposure (purified protein derivative [PPD], P > 0.18; WB, P < 0.04). PPD-positivity (%) was higher than controls only in HCWs with longer (> 5 years) MTB-exposure. The study suggests that the WB antibody might represent a more sensitive biological marker of MTB contact among exposed HCWs, related to the level of TB risk and detectable earlier than the PPD skin test, thus providing new tools for TB risk assessment in health care facilities.

Comparing Interferon- Release Assay with Tuberculin Skin Test Readings at 48-72 Hours and 144-168 Hours with Use of 2 Commercial Reagents

“…Finally, the need to assess the tuberculin response at 48-72 h [2,3,19] can be troublesome, especially in an indigent population [20]. Because of these shortcomings, numerous assays have been developed to quantify the response to tuberculous antigens [12,15,[21][22][23][24][25][26][27][28][29]. QuantiFERON-TB (Cellestis) is a test to aid the detection of persons infected with M. tuberculosis.…”

Legal and health aspects of sanitary waste management in Italy

“…Immune-type reactions can be caused by the dissemination of hairs or other components of animal origin that act as allergens. In the hospital sector, the commonest etiologic agents workers are exposed to are: hepatitis A, hepatitis B, hepatitis C, HIV viruses, bacteriological infections due to many different germs such as Bacillus, Staphylococcus, Mycobacterium, fungal infections from the Aspergillus variety, parasitosis; most of these occur accidentally or through the faulty application of safety procedures (Trevisan et al [3], Franchi et al [4], Lopez Hernandez et al [5]). The type of biological agent involved depends on the process units in which exposed workers are employed, but in the case of exposure to non-infectious agents, studies usually reveal exposure to bioaerosols containing live bacteria, moulds, bacterial mycotoxins and endotoxins.…”