title: 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.
authors.affiliation: Department of Medical Sciences, University of Modena, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Franchi
authors.forename: M
authors.initials: M
authors.lastname: Amicosante
authors.forename: E
authors.initials: E
authors.lastname: Rovatti
authors.forename: R
authors.initials: R
authors.lastname: Bonini
authors.forename: P
authors.initials: P
authors.lastname: Marchegiano
authors.forename: E
authors.initials: E
authors.lastname: Girardi
authors.forename: G
authors.initials: G
authors.lastname: Guaraldi
authors.forename: G
authors.initials: G
authors.lastname: Franco
authors.forename: C
authors.initials: C
authors.lastname: Saltini
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis; D015153:Blotting, Western / Q000379:methods*; D005260:Female; D006268:Health Facilities; D006282:Health Personnel; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D016273:Occupational Exposure; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000175:diagnosis* / Q000635:transmission
chemical_list: D000907:Antibodies, Bacterial