Clinical and laboratory investigation of latex allergy in healthcare workers

[摘要] ENGLISH ABSTRACT:Healthcare workers (HCWs) wear latex gloves to protect themselves and their patients againstthe transmission of microbial, viral and bloodborne diseases. These individuals are primarilyexposed to latex via cutaneous (direct contact) and mucocutaneous (inhalation of airborneallergens on glove powder) routes. Repeated exposure leads to the formation of circulatinglatex-specific IgE and subsequent sensitisation with varying clinical expression.The airconditioning system of the Tygerberg Hospital (TBH) complex was investigated for thepresence of aerosolised cornstarch glove powder and proteins. Dust samples were collectedfrom 14 areas with different levels of latex glove usage. Dust samples werespectrophotometrically compared to a calibration graph of pure glove powder. The detection ofstarch and proteins in all the dust samples confirmed the presence of glove powder andpossibly airborne latex allergens in the airconditioning ducts. As expected, the high exposureareas showed the highest concentrations of both starch and proteins. It is possible that otherproteins than latex were involved, but the confirmed high level of protein contamination shouldbe a cause for concern. Correlation between starch and protein levels was highly significant(p<0.01) in all instances.A total of 500 questionnaires were circulated for completion by HCWs from TBH. The responserate was 69.8%. After considering specific inclusion criteria, a study group of 152 individualswas compiled (28 males, 124 females). All subjects had current latex exposure and sufferedfrom at least three pre-defined symptoms.Serum was collected from all subjects and dermal fluid from 31 subjects. Total IgE and latex specificIgE analysis were done on all serum and dermal fluid samples. Latex-specific IgE waspositive (>0.35 IU/ℓ) in 23 serum and six dermal fluid samples. Skin prick tests (SPTs)for latexwere done on 59 subjects with negative serum latex-specific IgE and 34 had positive results.Twelve subjects with negative latex-specific IgE and latex SPTs underwent patch tests with theEuropean Standard Series, a piece of latex glove and glove powder in petrolatum. Threesubjects had positive results to one or more of these allergens.Western blot analysis for latex was done on all positive sera and dermal fluid collected fromthese subjects. Western blot analysis for latex proved to be more sensitive than the capRAST,because it was able to identify specific bands in samples with negative capRAST results. Allsubjects showed a band for Hev b 1, which has been confirmed as a powder-bound airborneallergen. Hev b 6.01 is associated with HCWs with cutaneous symptoms and this band was recognised by 81% of the subjects. These findings confirmed that airborne and cutaneousroutes are the major routes of exposure in HCWs.According to their laboratory results, subjects were divided into the following subgroups andcompared statistically: Group A (serum positive, n=23), Group B (SPT positive, n=34) andGroup C (negative, n=25). Group D (withdrawn, n=70) could not be used for statisticalcomparisons, due to incomplete results. An overall latex allergy prevalence of 38% was found.Group A differed significantly from Group B and Group C for most clinical and specialinvestigations. Group A and B were also combined to represent all subjects with positive results(Cohort AB). The Allergy Score and Class were highly significant when Cohort AB wascompared to Group C. The selection of clinical symptoms was confirmed to be relevant andwork-related deterioration on any of the symptoms should bear a high index of suspicion in theevaluation of latex allergy. Numerical indices and specific symptoms showed high positivepredictive values and the Allergy Score produced statistical significance in the positivesubgroups when compared to the negative subgroup. Paired statistical significance wasconfirmed between the Allergy Score and occupational exposure (number of years, hours andpairs per week).The areas with the highest occupational latex exposure in HCWs are the face and hands.Different occupations also have different levels of exposure and two subgroups of HCWs (16laboratory technologists and 13 theatre staff) were investigated for sebum content on differentfacial areas and the palms and dorsal areas of both hands. Baseline measurements were donebefore putting on gloves. In 21 subjects follow up measurements were done following three tofour hours of occupational exposure, but before washing their hands. Baseline and follow upvalues were compared for all the different anatomical regions. Levels on the forehead andcheeks increased over time, while the level on the nose decreased. All hand regions decreasedsignificantly during occupational exposure, suggesting that glove powder contributes to drynessof the skin.In conclusion, the problem posed by latex allergy will not be solved overnight and will probablyremain a major occupational hazard for years to come. It is currently not possible to avoidexposure to latex, but it is imperative to institute safety measures to prevent further sensitisationin predisposed individuals and manage those already affected.

[发布机构] Stellenbosch University