IgE-mediated allergy to chlorhexidine

Severe anaphylactic reaction to chlorhexidine during total hip arthroplasty surgery. A case report

Two consecutive hip surgery procedures in the same patient were aborted following a severe anaphylactic reaction of the patient. After the second procedure, the patient was diagnosed to be allergic to chlorhexidine, a component of the gel used to insert a urinary catheter. Chlorhexidine allergy is rare, and the delayed presentation may make it easy to overlook. In hip arthroplasty surgery, this may result in an abandoned procedure and the need for re-operation.

Perioperative allergy: uncommon agents

Anesthesia may often be considered as a high-risk procedure and anaphylaxis remains a major cause of concern for anesthetists who routinely administer many potentially allergenic agents. Neuromuscular blocking agents, latex and antibiotics are the substances involved in most of the reported reactions. Besides these three agents, a wide variety of substances may cause an anaphylactic reaction during anesthesia. Basically all the administered drugs or substances may be potential causes of anaphylaxis. Among them, those reported the most in literature include hypnotics, opioids, local anesthetics, colloids, dye, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), Iodinated Contrast Media (ICM), antiseptics, aprotinin, ethylene oxyde and formaldehyde, and protamine and heparins. No premedication can effectively prevent an allergic reaction and a systematic preoperative screening is not justified for all patients; nevertheless, an allergy specialist should evaluate those patients with a history of anesthesia-related allergy. Patients must be fully informed of investigation results, and advised to provide a detailed report prior to future anesthesia.

Anaphylaxis to ethylene oxide - a rare and overlooked phenomenon?

Spina bifida patients have been reported to be at increased risk of anaphylactic reactions during general anaesthesia. Following a reaction, latex is often incriminated as spina bifida patients are known to have an increased incidence of latex allergy. Ethylene oxide (EO) has recently been suggested to be an alternative cause, but in many cases reported in the literature, it seems that EO has not been considered as a cause. EO is a highly reactive gas widely used to sterilise heat-sensitive medical devices, and traces of EO can be found in many of the same products as latex. We present the case of a spina bifida patient with a known latex allergy, where EO was found to be the cause of an anaphylactic reaction during general anaesthesia. In addition, we describe measures taken during preparation of a subsequent general anaesthesia to minimise exposure to EO. Spina bifida patients seem to be at increased risk of sensitisation against EO due to repeated exposure, but only limited literature is available. To ensure that EO is considered as a cause in these cases, we recommend that testing for latex and EO go hand in hand following an anaphylactic reaction in this high-risk population.

An increase in serum tryptase even below 11.4 ng/mL may indicate a mast cell-mediated hypersensitivity reaction: a prospective study in Hymenoptera venom allergic patients

BACKGROUND

During a systemic hypersensitivity reaction (SR), an increase in serum tryptase compared to the baseline value is an indicator of mast cell activation, most often due to an IgE-mediated mechanism.

OBJECTIVE

To study the relevance of an increase in serum tryptase below the upper normal value of 11.4 ng/mL.

METHODS

Serum tryptase levels were measured in 35 patients with Hymenoptera venom hypersensitivity before and during venom exposure. Of these, 20 developed SR to stings or following venom injections during immunotherapy (reactors), while 15 tolerated reexposure to stings or venom injections during immunotherapy without SR (non-reactors). Serum tryptase was estimated at 2, 5 and 24 h after exposure and was compared to a baseline value obtained before or at least 72 h after exposure.

RESULTS

Considering circadian variation of serum tryptase, a relative increase to ≥135% of the baseline value (relative delta bound) was defined to indicate mast cell activation. Such an increase was observed in 17 of 20 reactors (85%), but none of 15 non-reactors. A serum tryptase of ≥11.4 ng/mL following venom exposure was observed in eight of the 20 reactors (40%) and 2 (13.3%) of the 15 non-reactors. Both these non-reactors also had an elevated baseline serum tryptase.

CONCLUSIONS AND CLINICAL RELEVANCE

Serum tryptase values obtained during a suspected hypersensitivity reaction must always be compared to a baseline value. A relative tryptase increase to ≥135% of the baseline value during a suspected hypersensitivity reaction indicates mast cell activation even below 11.4 ng/mL.

Perioperative anaphylaxis

The incidence of immune-mediated anaphylaxis during anesthesia ranges from 1 in 10,000 to 1 in 20,000. Neuromuscular blocking agents are most frequently incriminated, followed by latex and antibiotics, although any drug or substance used may be a culprit. Diagnosis relies on tryptase measurements at the time of the reaction and skin tests, specific immunoglobulin E, or basophil activation assays. Treatment consists of rapid volume expansion and epinephrine administration titrated to symptom severity.

BSACI guidelines for the investigation of suspected anaphylaxis during general anaesthesia

Investigation of anaphylaxis during general anaesthesia requires an accurate record of events including information on timing of drug administration provided by the anaesthetist, as well as timed acute tryptase measurements. Referrals should be made to a centre with the experience and ability to investigate reactions to a range of drug classes/substances including neuromuscular blocking agents (NMBAs) intravenous (i.v.) anaesthetics, antibiotics, opioid analgesics, non-steroidal anti-inflammatory drugs (NSAIDs), local anaesthetics, colloids, latex and other agents. About a third of cases are due to allergy to NMBAs. Therefore, investigation should be carried out in a dedicated drug allergy clinic to allow seamless investigation of all suspected drug classes as a single day-case. This will often require skin prick tests, intra-dermal testing and/or drug challenge. Investigation must cover the agents administered, but should also include most other commonly used NMBAs and i.v. anaesthetics. The outcome should be to identify the cause and a range of drugs/agents likely to be safe for future use. The allergist is responsible for a detailed report to the referring anaesthetist and to the patient's GP as well as the surgeon/obstetrician. A shorter report should be provided to the patient, adding an allergy alert to the case notes and providing an application form for an alert-bracelet indicating the wording to be inscribed. The MHRA should be notified. Investigation of anaphylaxis during general anaesthesia should be focussed in major allergy centres with a high throughput of cases and with experience and ability as described above. We suggest this focus since there is a distinct lack of validated data for testing, thus requiring experience in interpreting tests and because of the serious consequences of diagnostic error.

The role of antibacterial therapy in atopic eczema

IMPORTANCE OF THE FIELD

Atopic eczema is highly colonized with Staphylococcus aureus in lesional as in non-lesional skin. Antimicrobial therapy as part of a comprehensive therapeutic concept in atopic eczema has been discussed for a long a time.

AREAS COVERED IN THIS REVIEW

A complete literature review of the accessible publications concerning antibacterial and antiseptic therapy has been undertaken.

WHAT THE READER WILL GAIN

This review covers the literature on antimicrobial therapy in atopic eczema and will try to weigh the different publications in the field.

TAKE-HOME MESSAGE

A beneficial role for antibacterial/antiseptic therapy on top of anti-inflammatory therapy in atopic eczema has to be questioned. However, a role in prevention of overt skin infection seems possible.

[Anaphylaxis during anaesthesia]

BACKGROUND

Anaphylaxis is a serious life-threatening generalized or systemic hypersensitivity reaction. The aim of this paper is to provide knowledge on how to diagnose, treat and follow up patients with suspected anaphylaxis during general and local anaesthesia.

MATERIAL AND METHODS

The article is based on literature identified through a non-systematic search in PubMed, the Scandinavian Guidelines on anaphylaxis during anaesthesia and on own research.

RESULTS

Anaphylactic symptoms during anaesthesia vary with respect to severity. Manifestations from skin and the cardiovascular and respiratory systems are present simultaneously in approximately 70 % of patients. Early treatment with adrenaline, fluid and extra oxygen may be vital for survival without sequelae. The following patients should be assessed before anaesthesia: those with moderate or serious reactions or with reactions that raise suspicion of allergy which may cause problems in connection with future treatment. Neuromuscular blocking agents are the main cause of IgE-mediated anaphylaxis during anaesthesia in Norway. New research has shown that allergy towards neuromuscular blocking agents can develop after ingestion of cough syrup containing pholcodine (stimulates asymptomatic production of antibodies). These antibodies cause cross-sensibilisation with neuromuscular blocking agents. The cough syrup Tuxi was withdrawn from the Norwegian market during spring 2007.

INTERPRETATION

Allergic reactions during anaesthesia are rare and potentially life-threatening; patients should be followed up and treated in a standardized way.

Anaphylaxis to Patent Blue V. II. A unique IgE-mediated reaction

BACKGROUND

Patent Blue V (PBV) is injected in order to map sentinel nodes during cancer staging procedures. Anaphylactic reactions, allegedly IgE antibody mediated, have been reported. The aim of the study was to explore the immunological mechanism of anaphylaxis to PBV.

METHODS

PBV allergen threshold basophil sensitivity, CD-sens, was performed on cells from nine patients diagnosed as having had adverse reactions to PBV. The mechanisms of the CD-sens were studied by immunological and immuno-chemical methods.

RESULTS

Five of the nine patients had a positive CD-sens to PBV which was completely eliminated by washing the cells in phosphate buffered saline before allergen challenge. However, the positive CD-sens was completely reconstituted by incubating the cells in plasma or serum of that patient or the other PBV-anaphylactic patients for 15 min at room temperature. In some patients the factor mediating CD-sens was completely or partially destroyed by heating at +56 degrees C for 30 min or being exposed to the low pH used for elution from anti-Ig columns. A 1000-fold excess of monoclonal IgE blocked the reconstitution by approximately 50%.

CONCLUSION

Anaphylactic reactions to PBV are mediated by IgE antibodies giving a classical CD-sens reaction. However, the allergenic configuration seems to constitute a structure completely dependent on PBV, as a hapten, linked to a, so far, unknown carrier that seems to be unique for patients having experienced a PBV-induced reaction. Further studies are needed to characterize the postulated carrier.

The basophil activation test in immediate-type drug allergy

Diagnosis of drug allergy involves first the recognition of sometimes unusual symptoms as drug allergy and, second, the identification of the eliciting drug. This is an often difficult task, as the clinical picture and underlying pathomechanisms are heterogeneous. In clinical routine, physicians frequently have to rely upon a suggestive history and eventual provocation tests, both having their specific limitations. For this reason both in vivo (skin tests) and in vitro tests are investigated intensively as tools to identify the disease-eliciting drug. One of the tests evaluated in drug allergy is the basophil activation test (BAT). Basophils with their high-affinity IgE receptors are easily accessible and therefore can be used as indicator cells for IgE-mediated reactions. Upon allergen challenge and cross-linking of membrane-bound IgE antibodies (via Fc-epsilon-RI) basophils up-regulate certain activation markers on their surface such as CD63 and CD203c, as well as intracellular markers (eg, phosphorylated p38MAPK). In BAT, these alterations can be detected rapidly on a single-cell basis by multicolor flow cytometry using specific monoclonal antibodies. Combining this technique with in vitro passive sensitization of donor basophils with patients' serum, one can prove the IgE dependence of a drug reaction. This article summarizes the authors' current experience with the BAT in the diagnostic management of immediate-type drug allergy mediated by drug-specific IgE antibodies.

Surface disinfection properties of the combination of an antimicrobial peptide, ranalexin, with an endopeptidase, lysostaphin, against methicillin-resistant Staphylococcus aureus (MRSA)

AIMS

To characterize the antibacterial synergy of the antimicrobial peptide, ranalexin, used in combination with the anti-staphylococcal endopeptidase, lysostaphin, against methicillin-resistant Staphylococcus aureus (MRSA), and to assess the combination's potential as a topical disinfectant or decolonizing agent for MRSA. MRSA causes potentially lethal infections, and pre-operative patients colonized with MRSA are often treated with chlorhexidine digluconate and mupirocin cream to eradicate carriage. However, chlorhexidine is unsuitable for some patients, and mupirocin resistance is increasingly encountered, indicating new agents are required.

METHODS AND RESULTS

Using an ex vivo assay, ranalexin and lysostaphin tested in combination reduced viable MRSA on human skin to a greater extent than either compound individually. The combination killed bacteria within 5 min and remained effective and synergistic even in high salt and low pH conditions.

CONCLUSIONS

The combination is active against MRSA on human skin and under conditions that may be encountered in sweat.

SIGNIFICANCE AND IMPACT OF THE STUDY

Although the exact mechanism of activity remains unresolved, considering its specific spectrum of activity, fast killing kinetics and low likelihood of resistance arising, the combination of ranalexin with lysostaphin warrants consideration as a new agent to eradicate nasal and skin carriage of Staph. aureus, including MRSA.

In vitro evaluation of the antimicrobial activity of HM-242, a novel antiseptic compound

The antimicrobial activities of N(4)-octyl-6,6-dimethyl-N(2)-(4-methylbenzyl)-1,6-dihydro-1,3,5-triazine-2,4-diamine (HM-242), a novel synthetic compound, were compared with those of chlorhexidine gluconate (CHG). HM-242 was a more potent microbicide than CHG in vitro; however, its minimal inhibitory concentrations were similar. In particular, HM-242 killed various Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis, both efficiently and rapidly. HM-242 also showed potent virucidal activity against enveloped viruses such as influenza virus and herpes simplex virus. These characteristics suggest that HM-242 may well be useful as an antiseptic.

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.

Antibiotics for the allergist: part 2

OBJECTIVE

To review antibiotic use and selection for disorders commonly seen in allergy practice.

DATA SOURCES

MEDLINE searches were performed cross-referencing antibiotic, antimicrobial, management, and treatment with multiple disorders commonly seen in allergy practice. References of the chosen articles were also examined.

STUDY SELECTION

Articles were selected based on their relevance to the subject matter.

RESULTS

A large body of research is available relevant to both conventional and novel uses of antibiotics. The use of antibiotics is in question for some disorders, whereas novel approaches to therapy with macrolide antibiotics are areas of active investigation. Meanwhile, patterns of microbial resistance continue to evolve.

CONCLUSION

For decades, antibiotics have been traditional first-line treatment for many disorders. Currently, this paradigm appears to be shifting as periods of observation come into favor and nonbacterial causes of inflammation are under greater scrutiny. Nonetheless, appropriate antibiotic selection often remains a key element in the treatment of these disorders. Knowledge of the relevant microbiology is an inherent requirement in selecting antibiotic therapies and necessitates awareness of current trends in bacterial resistance.

The basophil activation test in immediate drug allergy

Diagnosis of drug allergy is not always straight forward for several reasons. First, a broad spectrum of drugs can elicit various immune-mediated diseases with distinct pathomechanism, secondly, although exact epitope identification is not mandatory for clinical diagnosis, the epitope that causes the reaction is frequently unknown, thirdly in vitro or in vivo test results might not be predictive of a clinical situation, and finally the gold standard or reference test for diagnosis, the drug challenge, is a complicated and sometimes dangerous endeavour. Upon challenge with specific allergens that cross-link membrane-bound IgE antibodies, basophils upregulate the expression of different activation markers such as CD63 and CD203c. These immunophenotypic alterations can be detected on a single-cell basis by multicolour flow cytometry using specific monoclonal antibodies in the basophil activation test (BAT). This review intends to summarise our current experience with the BAT in the diagnostic management of immediate-type allergy to drugs and related compounds that are generally (but not always) mediated by drug-specific IgE antibodies.

Improving adherence to surgical hand preparation

At present, no universal agreement on detailed practice for surgical hand preparation exists. In order to fill this gap, in 2002 a Franco-German recommendation for surgical hand preparation was published as a first step towards a generally accepted European recommendation. Based on an assessment of the actual literature, a protocol for surgical hand preparation is discussed with the aim to recommend evidence-based standard procedures including prerequisites, washing and disinfection phase, and its practical implementation. In contrast to hygienic hand disinfection, for surgical hand preparation compliance is not an issue, since it mostly is regarded as a ceremony which is carried out without exception. Nevertheless, the following factors influence acceptance and efficacy: skin tolerance, ease of use, duration of procedure, and recommended time), potential for impaired efficacy due to incorrect performance of the procedure, possibility of systemic risks and irritating potential by applied preparations, religious restrictions, ecological aspects, costs and safety. Here, we report our experience with the introduction of a new hand preparation regime in all surgical disciplines in our university hospital based on the above factors. The following statements were evaluated: 1) The immediate efficacy of an alcohol-based hand disinfectant is impaired by a preceding hand wash for up to 10 minutes. Therefore hands should not be routinely washed before the disinfection period unless there is a good reason for it such as visible soiling. 2) A shortened application time (1.5 minutes) is equal to 3 min in terms of efficacy. 3) Hands should be air dried before gloves are put on, otherwise the perforation rate of gloves will increase. 4) The efficacy of alcohol-based disinfectants is significantly higher when hands are allowed to dry for 1 minute after the washing phase and before the disinfection phase. To clarify the above questions before the establishment of the modified technique, the surgical team was invited to a meeting. As a result, the heads of surgical departments supported the new technique and decided to change their practice.