IgE-mediated chlorhexidine allergy: a new occupational hazard?

BACKGROUND: Chlorhexidine is an effective antimicrobial agent commonly used in UK hospitals, primarily for skin decontamination. Recent UK infection control guidelines recommend the use of 2% chlorhexidine solution in specific clinical settings, thus increasing chlorhexidine use by health care workers (HCWs). Chlorhexidine has been widely reported to cause IgE-mediated allergic reactions (from urticaria and angioedema to anaphylaxis) among patients undergoing surgery/invasive procedures. Despite its widespread use in health care settings, there are no reports of clinically confirmed occupational IgE-mediated chlorhexidine allergy. AIMS: To identify cases of chlorhexidine allergy among health care workers. METHODS: A questionnaire was distributed among HCWs in wards and operating theatres at a UK district general hospital to raise awareness of potential chlorhexidine allergy and to invite those with possible clinical allergy to come forward for further testing. Diagnosis was based on an appropriate clinical history with positive serum-specific IgE to chlorhexidine and/or positive skin prick testing. RESULTS: Four cases of occupational IgE-mediated allergy to chlorhexidine were identified. CONCLUSIONS: Despite its excellent antimicrobial properties, chlorhexidine is an occupational allergen. We suggest that chlorhexidine allergy be included in the differential diagnosis of HCWs presenting with work-related allergic symptoms. Increased awareness and easier access to chlorhexidine-specific IgE serological testing should facilitate early diagnosis of affected HCWs, allowing appropriate avoidance measures to be instigated--thus reducing the risk of potentially severe allergic reactions in the future.

Case Report: Resolution of chronic urticaria following treatment of odontogenic infection.

Background: Chronic spontaneous urticaria (CSU) is a condition characterised by the presence of hives with/without angioedema, that affects individuals on more days than not for 6 weeks or more. The role of infection as a potential trigger for CSU is well described, but the current clinical guidelines do not recommend routine screening for underlying infections. Main observations: We report a case of severe prolonged chronic spontaneous urticaria in a 19-year-old, that went into rapid remission following the treatment of dental infection. Conclusions: Clinicians should recognise the potential role that infection can have in causing chronic urticaria. There should be a low threshold to treat infection in such circumstances.

Hyper-IgM syndrome type 4 with a B lymphocyte-intrinsic selective deficiency in Ig class-switch recombination.

Hyper-IgM syndrome (HIGM) is a heterogeneous condition characterized by impaired Ig class-switch recombination (CSR). The molecular defects that have so far been associated with this syndrome - which affect the CD40 ligand in HIGM type 1 (HIGM1), CD40 in HIGM3, and activation-induced cytidine deaminase (AID) in HIGM2 - do not account for all cases. We investigated the clinical and immunological characteristics of 15 patients with an unidentified form of HIGM. Although the clinical manifestations were similar to those observed in HIGM2, these patients exhibited a slightly milder HIGM syndrome with residual IgG production. We found that B cell CSR was intrinsically impaired. However, the generation of somatic hypermutations was observed in the variable region of the Ig heavy chain gene, as in control B lymphocytes. In vitro studies showed that the molecular defect responsible for this new HIGM entity (HIGM4) occurs downstream of the AID activity, as the AID gene was induced normally and AID-induced DNA double-strand breaks in the switch micro region of the Ig heavy chain locus were detected during CSR as normal. Thus, HIGM4 is probably the consequence of a selective defect either in a CSR-specific factor of the DNA repair machinery or in survival signals delivered to switched B cells.

Anaphylaxis after disinfection with 2% chlorhexidine wand applicator.

A 54-year-old man with end-stage renal failure attended for dialysis. Within seconds of applying 2% w/v chlorhexidine (ChloraPrep 3 mL Wand Applicator) to the skin surrounding the insertion point of his dialysis catheter (Tesio catheter), he developed pruritus, urticaria, shortness of breath, hypotension and reduced responsiveness. Treatment for anaphylaxis was initiated with rapid improvement of his symptoms, and he made a full recovery. Allergy to chlorhexidine was confirmed with skin testing, and the patient was warned against all future exposure to chlorhexidine. Subsequent dialysis without chlorhexidine was uneventful.

Does the Maternal Serum IgG Level during Pregnancy in Primary Antibody Deficiency Influence the IgG Level in the Newborn?

Purpose. To find out if the serum IgG level in the newborn baby was affected by low maternal serum IgG during pregnancy in two newly diagnosed primary antibody deficient patients. Method. Infant cord blood IgG level was compared with maternal IgG level in 2 mothers with newly diagnosed primary antibody deficiency, who declined replacement IgG treatment during pregnancy. Results. Both mothers delivered healthy babies with normal IgG levels at birth. Conclusions. The normal IgG levels and sound health in these 2 babies in spite of low maternal IgG throughout pregnancy raise interesting discussion points about maternofoetal immunoglobulin transport mechanisms in primary antibody deficiency.