Outbreak of transient conversions of the QuantiFERON-TB Gold In-Tube test in laboratory health care worker screenings.

Gamma interferon release assays were recently introduced in health care worker (HCWs) screenings for tuberculosis surveillance. In longitudinal surveys, conversions and reversions are seen, and yet whether these changes are unspecific or are an expression of new infections and microbial clearance remains unclear. In order to further elucidate these changes, we analyzed an outbreak of 15 transient conversions in 53 HCWs who operate in the same laboratory and handle specimens potentially containing Mycobacterium tuberculosis who underwent screening by the QuantiFERON-TB Gold In-Tube (QFT-GIT) test between 11 May and 30 June 2010: 15/46 (33%) negative HCWs showed a conversion and then reverted after 7 to 107 days. To validate these results, an evaluation of methodological procedures and test reliability, as well as an analysis of results obtained during the same period and processed by the same laboratory, was carried out. For the latter purpose, QFT-GIT results determined for 78 ward HCWs who underwent screening during the same period and were employed in departments with at least 3 infectious tuberculosis patients per year or had cared for an infectious patient without airborne precautions were analyzed with the following results: 6/63 (9%) HCWs with negative results in 3 different departments showed transient conversion (P = 0.002; odds ratio, 4.60; 95% confidence interval, 1.62 to 13.04). A retrospective survey of in-house biosafety practices led to determination of a single exposure factor within the laboratory. These data emphasize the validity of the hypothesis that a transient conversion demonstrates the presence of a real tubercular infection and could be an important indicator for occupational biosafety concerns. They also confirm that subjects with recent conversion should be retested before chest radiography and chemotherapy is offered.

[Consensus Document. Update on latex exposure and use of gloves in Italian health care settings]. / Documento di Consenso. Aggiornamenti in tema di esposizione a latice e impiego di guanti in ambito sanitario.

This consensus document was prepared by an Italian working group including occupational health professionals involved for many years in the management of glove- and latex-related problems in health care settings. The aim of this document was to address the most significant technical, epidemiological, clinical, environmental and prevention problems related to the use of gloves and latex. The group's recommendations are based on scientific evidence and practical experience but they cannot be considered as final. These topics need to be periodically revised. The following points should be taken into account: glove quality seems to have improved considerably but the information on glove features provided by the manufacturers is often still inaccurate or incomplete; the regulations in force provide that the manufacturers perform tests to supply evidence for the quality of the products but they do not indicate which analytical method should be used and they do not require that the results be reported in the technical data sheets. Thus the manufacturers have only to declare that their products are "in accordance with the rules"; therefore, purchasers should require the manufacturing companies to supply detailed information and verify their reliability. Moreover, the rules should be adapted to higher quality standards; occupational physicians must be involved for the correct choice and purchase of protective gloves; the use of gloves (in particular latex gloves) and latex devices in health care settings should be based on specific criteria: procedures must be available stating which kind of gloves are suitable for specific tasks. When exposure to latex cannot be avoided it is necessary to choose products that have good biocompatibility (e.g., powder free-gloves with low allergen content); once and for all latex powdered gloves should no longer be commercially available! labels for latex devices (including gloves) should report the extractable latex allergen content. Limit values for extractable latex allergens should be established; the use of synthetic rubber gloves should be encouraged since some materials (e.g., neoprene and nitrile rubber) appear to have physical properties and protective efficacy similar to latex, plus good biocompatibility; more studies should be promoted to verify the protective efficacy of new synthetic materials; health care workers should be informed about the advisability and usefulness of using materials other than latex; health care services should not cause additional risks but rather highlight the advantages for workers and patients if the use of latex gloves and devices is minimized.

Long-term persistence of anti-HBs after vaccination against HBV: an 18 year experience in health care workers.

The aim of the present study was to evaluate the long-term persistence of seroprotection after hepatitis B virus (HBV) vaccination. A total of 422 health care workers (HCWs) were evaluated 4.8-18.8 years after primary immunization (mean follow-up 11.8 years); 241 of them had received plasma-derived vaccines and 181 had been given yeast-derived vaccines; 107 subjects received a booster dose of yeast-derived vaccine 6 years after primary immunization with either plasma-derived or yeast-derived vaccines. Seroprotection was assumed when the anti-HBs titers were >10 mIU/ml. The overall response after primary immunization was 98.8%. Among subjects who reached a 10 year follow-up, those treated with plasma-derived vaccine had a seroprotection rate of 87.8 compared to 81.6% of those vaccinated with yeast-derived vaccines (P<0.001). Anti-HBs geometric mean titers (GMTs) after primary immunization were similar in the two groups, but were significantly lower at 10 years follow-up in the group that had received a yeast-derived vaccine (104 mIU/ml versus 244 mIU/ml in those who used a plasma-derived vaccine, P<0.05). Anti-HBs GMTs in the 107 subjects given the booster dose were 242 mIU/ml pre-booster titer, and rose to 35,171 mIU/ml after the booster dose. A mean 10.1 years after the booster dose, GMTs were 952 mIU/ml. Overall, the anti-HBs seroprotection rate was 95.4% (102 subjects). Based on GMT results, no booster dose is necessary in healthy adults for at least 10 years after primary immunization.