Rapid oral desensitization to trimethoprim-sulfamethoxazole in infants and children.

BACKGROUND: Although trimethoprim-sulfamethoxazole is the preferred chemoprophylaxis against Pneumocystis carinii pneumonia, there are frequent IgE-mediated reactions among children infected with the human immunodeficiency virus (HIV). Oral desensitization allows more patients to receive chemoprophylaxis, but it has been studied in only a limited number of children. METHODS: We desensitized five children infected with the HIV using a rapid, 4-h oral protocol. RESULTS: Three children (including two infants) successfully completed desensitization and started maintenance therapy, but the other two experienced reactions that precluded further administration of trimethoprim-sulfamethoxazole. CONCLUSIONS: We conclude that a rapid, oral trimethoprim-sulfamethoxazole desensitization protocol is safe and, in some instances, effective among HIV-infected children and infants with a history of non-life-threatening, IgE-mediated reactions to trimethoprim-sulfamethoxazole.

Latex hypersensitivity in children: clinical presentation and detection of latex-specific immunoglobulin E.

OBJECTIVE: To better understand the clinical characteristics, diagnosis, and possible prevention of immediate hypersensitivity reactions to latex in a hospitalized, pediatric patient population. METHODS: We performed a retrospective case analysis of the first 35 patients with latex allergy evaluated by our service over a 2-year period at our institution. Characteristics of patients and clinical reactions were analyzed and the presence of latex-specific immunoglobulin E was assessed using in vitro methods. In a limited group of patients, the success of strict environmental control and premedication with steroids and antihistamines was evaluated for the prevention of latex allergic reactions. RESULTS: The majority of our patients had life-threatening reactions. In previous reports, most pediatric patients underwent reactions in the perioperative period and belonged to two well-recognized "high-risk" patient groups (spina bifida and genitourinary malformations). In our series, 21 patients (60%) had reactions outside of the operating room setting, and 14 patients (40%) had primary diagnoses outside of the previously recognized "high-risk" groups. Many patients had a history of multiple surgical procedures, and a history of a surgical procedure in the first year of life was very common. A pre-existing clinical history of latex allergy was present in only 18 of the 35 patients, and a severe or life-threatening allergic reaction was the presenting feature of latex allergy in 11 of the 35 patients. Using in vitro assays, we were able to detect latex-specific immunoglobulin E in the sera of all but two of our patients. Latex gloves and latex-containing intravenous sets were common triggers for reactions. When exposure to latex occurs systemically, as through an intravenous line, premedication with steroids and antihistamines may fail to protect against anaphylaxis. CONCLUSIONS: Our experience indicates that the incidence of latex hypersensitivity in children is increasing, that the circumstances (patient profile, hospital location, route of exposure) in which life-threatening reactions may occur are more broad than previously reported, and that a better understanding of both environmental sources of latex antigens and host responses to latex exposure are needed for improved prevention of serious reactions.

Flow cytometric measurement of immunoglobulin E to natural latex proteins.

Immediate hypersensitivity to natural latex (NL) occurs in sensitized individuals after repeated exposure to products or devices containing NL components. Since allergic reactions to NL proteins are quite frequent and may be quite serious, diagnostic assays are needed to identify individuals at risk. A number of latex proteins have been considered the major antigens, but they have been incompletely characterized. There is no standard material available for skin testing. In vitro diagnostic tests, such as the radioallergosorbent test (RAST), are time consuming and their sensitivity and specificity remain to be proven. We have developed a rapid microsphere-based, fluorescence-activated flow cytometry assay for the measurement of NL protein-specific human immunoglobulin E and have compared it with both the enzyme-linked immunosorbent assay and radioallergosorbent test methods. By using the total purified NL protein fraction isolated from raw ammoniated NL sap as the antigen, the flow cytometry assay was both sensitive and specific for the detection of NL protein-specific human immunoglobulin E in the sera of sensitized pediatric patients.

Latex hypersensitivity reactions despite prophylaxis.

Latex rubber hypersensitivity represents a significant problem facing the medical, surgical, radiologic, and dental professions. As a tertiary care center, the Childrens Hospital of Philadelphia has a large population of patients with spina bifida and complex genitourinary anomalies; a number of these children have latex rubber allergy, which may first present as intraoperative anaphylaxis. Although there is no substitute for complete antigen avoidance, all medical products containing latex rubber may not have suitable alternatives. Therefore, we have formulated a protocol to prevent perioperative reactions through the use of prophylactic medications and the limitation of latex exposure. This regimen includes steroids, antihistamines, and bronchodilators when indicated. In four children, prophylaxis failed perioperatively because of parenteral infusion of latex rubber proteins.