tive predictive value of provocation tests with beta-lactams. Allergy 2010; 65: 327-332.Provocation tests with beta-lactams play an important role in the diagnosis of hypersensitivity reactions to these antibiotics (1-3). In particular, drug provocation tests are included in both of the diagnostic algorithms of the European Network for Drug Allergy (ENDA) for evaluating immediate and nonimmediate hypersensitivity reactions to beta-lactams (2, 3). Immediate reactions are those occurring within the first hour after the last drug administration and are manifested clinically by urticaria, angioedema, rhinitis, bronchospasm and anaphylactic shock. Non-immediate reactions occur more than one hour after the last drug administration. The main non-immediate reactions are maculopapular eruptions and delayed-appearing urticaria/angioedema.Indications of provocation tests with beta-lactams are extensive for the European Academy of Allergology and Clinical Immunology -ENDA group (2-4) and more restricted for the American Academy of Allergy Asthma and Immunology (5). Recently, ENDA simplified the protocol of provocation tests in patients with immediate reactions to beta-lactams by reducing the number of doses (6). In addition, the ENDA questionnaire (7) allows patients with a potential beta-lactam allergy to be identified, and recommendations on drug provocation tests are available (4).Though not well established, the negative predictive value is important for both the patient and the physician. The patient has to know whether a reaction can occur after taking a drug, which was tested negatively. It is now well known that adverse drug reaction and especially drug allergy/ hypersensitivity are sources of anxiety and led to an avoidance of the drug. On the other hand, the physician has to Keywords allergy; beta-lactams; drug provocation tests; hypersensitivity; negative predictive value. Only 118 (25.8%) were re-exposed to the negatively tested beta-lactam. Nine (7.6%) reported a non-immediate (occurring more than 1 h after drug administration) reaction: five urticaria, three exanthema and one undefined cutaneous reaction. None were severe. Only four accepted a re-challenge, negative in two cases and positive in the two others. The negative predictive value was 94.1% (89.8-98.3) (111 out of 118 patients). Conclusion: Although the negative predictive value of drug provocation tests may not be 100%, none of the false negative patients experienced a life-threatening reaction. This should reassure doctors who might hesitate to prescribe beta-lactams, even in patients with negative allergic work-ups.

The most important causes of anaphylaxis in our study were foods, and the most common symptoms were respiratory and cutaneous. The prevalence of anaphylaxis was higher in males and, in two thirds of patients there was a history of atopy. Despite being the primary and most important treatment for anaphylaxis, adrenaline is still used in only a minority of these cases.

IntroductionResults of systematic screening of healthcare workers (HCWs) for tuberculosis (TB) with the tuberculin skin test (TST) and interferon-γ release assays (IGRA) in a Portuguese hospital from 2007 to 2010 are reported.MethodsAll HCWs are offered screening for TB. Screening is repeated depending on risk assessment. TST and QuantiFERON Gold In-Tube (QFT) are used simultaneously. X-ray is performed when TST is > 10 mm, IGRA is positive or typical symptoms exist.ResultsThe cohort comprises 2,889 HCWs. TST and IGRA were positive in 29.5%, TST-positive but IGRA-negative results were apparent in 43.4%. Active TB was diagnosed in twelve HCWs - eight cases were detected during screening and four cases were predicted by IGRA as well as by TST. However, the progression rate in IGRA-positive was higher than in TST-positive HCWs (0.4% vs. 0.2%, p-value 0.06).ConclusionsThe TB burden in this cohort was high (129.8 per 100,000 HCWs). However, the progression to active TB after a positive TST or positive IGRA was considerably lower than that reported in literature for close contacts in low-incidence countries. This may indicate that old LTBI prevails in these HCWs.

The prevalence of latent tuberculosis (TB) infection (LTBI) and the incidence of active tuberculosis in healthcare workers (HCWs) in a Portuguese hospital were examined.This cross-sectional study comprises 4,735 hospital workers screened between May 2005 and September 2008. Tuberculin skin test (TST) and interferon-c release assay (IGRA) were used simultaneously in 1,219 HCWs (25.7%). Radiographs were taken in symptomatic HCWs or in testpositive HCWs. The tests were repeated annually or bi-annually depending on risk assessment.IGRA was positive in 32.6% and TST in 74.2% of the HCWs. Years spent in healthcare were a risk factor for a positive IGRA, but not for a positive TST. Repeated bacillus Calmette-Guérin vaccination increased the probability of TST+/IGRA-discordance (35.4% versus 54.4%, respectively). In those tested three times with TST during the study period (n559), the mean diameter of TST increased from 5 to 7 to 10 mm. Within 3 yrs, 31 HCWs were diagnosed with active TB (annual incidence rate 191 out of 100,000 people). In eight HCWs with active TB, TST and IGRA were performed at the time of diagnosis and each test was positive.TB burden in HCWs in Portugal is high. With IGRA, the number of radiographs needed to exclude active TB could have been reduced by about half without missing a case of active TB. Therefore IGRA should be introduced into TB screening programmes.