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Background Antituberculosis (anti-TB) drug allergy often involves multiple concurrently administered drugs which subsequently need to be reinitiated as no better alternatives exist. Objective To describe the results of tailored sequential desensitization-rechallenge (D-R) for anti-TB drug allergy. Methods Consecutive patients who had undergone D-R to anti-TB drugs between 1 September 1997 and 31 January 2012 were recruited. Following resolution of the acute reaction, anti-TB drug was restarted at 1:6,000 to 1:3 of the final daily dose (FDD), with gradual single or multiple step daily dose escalation to the FDD. Subsequent drugs were sequentially added ≥3 days later when the preceding drug was tolerated. Full blood count and liver function tests were monitored prior to addition of each new drug. Results There were 11 patients of whom 10 were male, predominantly Chinese (8 patients). Regimens comprised at least 3 drugs: isoniazid (INH), rifampicin (RIF), ethambutol (EMB), pyrazinamide (PZA), or streptomycin. All patients had nonimmediate reactions, with cutaneous eruptions, where maculopapular exanthema (MPE) was the most common (8 patients). Drug-induced hypersensitivity syndrome (DIHS) occurred in 6 patients, and Stevens Johnson syndrome (SJS) in 2 patients. D-R to INH was successful in 7/9 patients (77.8%) and to RIF/EMB/PZA/streptomycin in all. Of the 2 patients who failed INH D-R, 1 developed fever and MPE on day 3, the other MPE on day 8. D-R with INH and RIF respectively was successful in 2 patients with SJS. Among DIHS patients, 1 failed D-R with INH (fever and MPE on day 3). There were 23/25 (92%) successful D-R among the 11 patients. All patients completed TB treatment of ≥5 months' duration with no cases of drug-resistant TB. Conclusion Tailored sequential TB drug D-R is successful where no better alternative therapies are available, with careful dose escalation and close monitoring, and after a careful risk-benefit assessment.

Background All Singaporean males undergo medical screening prior to compulsory military service. A history of possible food allergy may require referral to a specialist Allergy clinic to ensure that special dietary needs can be taken into account during field training and deployment. Objective To study the pattern of food allergy among pre-enlistees who were referred to a specialist allergy clinic to work up suspected food allergy. Methods Retrospective study of all pre-enlistees registered in the Clinical Immunology/Allergy New Case Registry referred to the Allergy Clinic from 1 August 2015 to 31 May 2016 for suspected food allergy. Results One hundred twenty pre-enlistees reporting food allergy symptoms other than rash alone were referred to the Allergy Clinic during the study period. Of these, 77 (64.2%) had food allergy. Among those with food allergy, mean age was 19.1 ± 1.5 years. They comprised predominantly Chinese (66.2%) and Malays (20.8%). The most commonly reported foods were shellfish/crustaceans (78%), peanut (15.6%), and egg (6.5%). Self-limiting oral allergy syndrome, OAS (itchy lips and throat with/without lip angioedema) was the most common manifestation (n = 33, 42.9%) followed by anaphylaxis (n = 23, 29.9%). Majority of OAS was from shellfish/crustacean (90.6%); of which shrimp (30.3%), crab (15.2%), and lobster (3.0%) were the most common. Mild childhood asthma (69.7%), allergic rhinitis (6.3%), and eczema (6.1%) were the most common atopic conditions among individuals with shellfish/crustacean OAS. This pattern was similar for shellfish/crustacean anaphylaxis. Skin prick tests were most commonly positive for shrimp (OAS 87.1% vs. anaphylaxis 100%), crab (OAS 95.8% vs. 90.9%), and lobster (OAS 91.7% vs. 63.6%). Conclusion OAS to shellfish/crustaceans was more common than anaphylaxis among this study population of young males referred for food allergy symptoms other than rash alone.

Background:Blomia tropicalis is an important domestic dust mite in the tropics and subtropics. This study describes cDNA cloning of the group 4 allergen of B. tropicalis, and the evaluation of the sensitization of this allergen in atopic populations from 2 geographic regions. Methods: cDNA cloning was carried out using the Smart RACE cDNA amplification kit. The full-length Blo t 4 cDNA was isolated by cDNA library screening, 5′ and 3′ rapid amplification of cDNA ends and long-distance PCR. Sequence analysis was performed with a combination of the Clustal W, CGC and Blast program packages. The cDNA was expressed in Pichia pastoris yeast. The skin prick test was used to evaluate the sensitization profile of recombinant Blo t 4, crude dust mite allergen extracts and major B. tropicalis recombinant allergen Blo t 5. Results: The cloned Blo t 4 had a molecular weight of 56 kDa and had 68% amino acid homology with group 4 allergens of Dermatophagoides pteronyssinus and 65% with those of Euroglyphus maynei. A sensitization profile to the expressed recombinant Blo t 4 allergen (28%) showed an unusually higher frequency than to the major allergen Blo t 5 (22%) in allergic subjects from Chengdu, PR China. In comparison, the subjects from Singapore showed very low sensitization to Blo t 4 (4%) compared with Blo t 5 (84%). Conclusions: Group 4 allergens of B. tropicalis may be an important dust mite allergen in certain distinct populations.

ummary Background The importance of assessing health-related quality of life (HRQL) of patients with allergic rhinitis (AR) has been well established, but the specific roles of rhinitis-specific or general health instruments have not been delineated. Objective We analysed the psychometric properties of a disease-specific instrument, the Rhinoconjunctivitis Quality-of-Life Questionnaire (RQLQ) and the general health instrument, the Medical Outcome Short-Form 36 (SF-36) as they are employed in combination in patients with persistent AR in clinical practice. Method We analysed the data collected from a prospective study of 43 newly diagnosed patients with persistent AR and 44 controls. We interviewed the patients four times, at baseline, weeks 4, 8 and 10. Results The RQLQ and SF-36 have good discriminative property, internal consistency, and test–retest reliability. The RQLQ is superior to the SF-36 as an evaluative instrument because more of its domains respond to change, the magnitude of change was greater, and the response was faster. The SF-36 is more susceptible to floor and ceiling effects. Both instruments are unsuitable for mildly symptomatic patients based on Rasch model analysis. Each questionnaire assesses a distinct and significant portion of the total HRQL of persistent AR. Conclusion The SF-36 and RQLQ are good for discriminating rhinitis patients from controls, but the former is poor for detecting changes in QOL. Both are inappropriate for mildly symptomatic patients. Each instrument measures non-overlapping halves of the measurable HRQL. For an assessment of the HRQL in persistent AR that is complete and responsive both instruments should be employed together.

Background Drug allergies are unpredictable immunologic adverse effects, usually immunoglobulin E-mediated immediate hypersensitivity or T-cell-mediated delayed hypersensitivity. There is a paucity of accurate prospective data on drug allergy in hospitalized patients. Objective To describe the incidence, manifestations, and outcome of drug allergy in hospitalized patients. Methods All newly developed cases, confirmed or suspected, of drug allergy in inpatients using a network-based electronic notification system. Each notification was evaluated by an allergist-immunologist during the same admission. Results From December 1, 1997 to December 31, 1999, 366 cases were reported from a total of 90,910 admissions. After review, only 210 cases were verified to have drug allergy. Antimicrobials and anti-epileptic drugs comprised 75% of the drug allergies reported. Cutaneous eruptions were the most common clinical presentation (95.7%), with maculopapular rash being the most common morphology. Systemic manifestations occurred in 30%, of which hepatitis was the most common. Serious adverse reactions such as Stevens-Johnson syndrome, toxic epidermal necrolysis, and generalized exfoliative dermatitis occurred in 11 (5.2%) patients. There was no case of anaphylaxis attributable to drug allergy. After adjusting for underreporting, the incidence of drug allergy in our hospitalized patients was 4.20 per 1,000 (95% confidence interval [CI] 2.93 to 5.46), drug allergy developing during the course of inpatient treatment 2.07 per 1,000 (95% CI 1.45 to 2.69), and mortality attributable to drug allergy 0.09 per 1,000 (95% CI 0.06 to 0.12) hospitalizations. Conclusions A network-based, allergist-immunologist-verified, surveillance system enables more accurate labeling of drug allergy. The incidence of drug allergy and mortality in hospitalized patients is low.

SummaryBackground Shellfish allergy in Singapore is highly prevalent, and shrimp allergy is the most common. Objective This study aims to evaluate the clinical characteristics and immunological phenotype of shellfish allergy in this population. Methods Patients with self-reported shellfish allergy were recruited from outpatient clinics of three large hospitals and from a population survey. Open oral food challenges (OFC) to glass prawn (Litopenaeus vannamei) and tiger prawn (Penaeus monodon) were carried out on all patients except for those who had a history of severe anaphylaxis. Skin prick tests (SPT) and specific IgE to crude and recombinant allergens were carried out to evaluate shrimp and dust mite sensitization. Immunoblots were used to assess IgE-binding proteins. Results The 104 patients recruited were categorized into shellfish allergic (SA) when OFC was positive or had a history of severe anaphylaxis (n = 39), shellfish tolerant (ST) when OFC was negative (n = 27), and house dust mite positive controls (HDM+) who were ST (n = 38). Oral symptoms (87.1%) were the predominant clinical manifestation. Positive challenge doses ranged from 2 to 80 g of cooked shrimp, with 25/52 patients reacting to either one or both shrimps challenged. The presence of specific IgE to shrimp either by SPT and/or ImmunoCAP® assay provided diagnostic test sensitivity of 82% and specificity of 22.2%. The inclusion of specific IgE to shrimp tropomyosin and IgE immunoblots with shrimp extracts did not improve the diagnostic proficiency substantially. Conclusions and Clinical Relevance This study highlights the predominance of oral symptoms in shrimp allergy in tropical Asia and that a high provocation dose may be necessary to reveal shrimp allergy. Furthermore, specific IgE diagnostic tests and immunoblots were of limited use in this population.

Blomia tropicalis is an important domestic dust mite in the tropics and subtropics. This study describes cDNA cloning of the group 4 allergen of B. tropicalis, and the evaluation of the sensitization of this allergen in atopic populations from 2 geographic regions.cDNA cloning was carried out using the Smart RACE cDNA amplification kit. The full-length Blo t 4 cDNA was isolated by cDNA library screening, 5' and 3' rapid amplification of cDNA ends and long-distance PCR. Sequence analysis was performed with a combination of the Clustal W, CGC and Blast program packages. The cDNA was expressed in Pichia pastoris yeast. The skin prick test was used to evaluate the sensitization profile of recombinant Blo t 4, crude dust mite allergen extracts and major B. tropicalis recombinant allergen Blo t 5.The cloned Blo t 4 had a molecular weight of 56 kDa and had 68% amino acid homology with group 4 allergens of Dermatophagoides pteronyssinus and 65% with those of Euroglyphus maynei. A sensitization profile to the expressed recombinant Blo t 4 allergen (28%) showed an unusually higher frequency than to the major allergen Blo t 5 (22%) in allergic subjects from Chengdu, PR China. In comparison, the subjects from Singapore showed very low sensitization to Blo t 4 (4%) compared with Blo t 5 (84%).Group 4 allergens of B. tropicalis may be an important dust mite allergen in certain distinct populations.

pared to Group1B (Der p 10 [33.3%vs9.7%], and Pen m 1 [33.3%vs9.7%], p

Background Type I hypersensitivity reaction to metronidazole and its skin testing are rarely reported. A 69 year old lady had laproscopic cholecystectomy on 27September 2010. Post surgery, IV ciprofloxacin 400mg and metronidazole 500mg were infused at 8.00 pm. Within 30 minutes, she experienced pruritus and noted erythema on her left forearm followed by urticaria over upper limbs and chest. She reported mild shortness of breath and dizziness. There was no hypotension or angioedema. This was her first such reaction to drugs. Both antibiotics were stopped and IV hydrocortisone and oral chlorpheniramine prescribed. She was referred to our allergy service for suspected allergy to either ciprofloxacin or metronidazole. On assessment, she had received antibiotics on several occasions in the past and had reacted to ceftriaxone with pruritic maculopapular rashes. She had consumed metronidazole in June 2009 and ciprofloxacin in June 2009 and July 2010. A clinical diagnosis of Type I allergy to metronidazole was made.