Radioallergosorbent testing for penicillin allergy in family practice.

OBJECTIVES: To determine (a) the prevalence of patients supposedly allergic to penicillin who have a positive radioallergosorbent test (RAST) result for penicillin G or V and (b) the predictive power of family physicians'' clinical judgement that a patient who is supposedly allergic to penicillin will have a positive RAST result. DESIGN: Prospective multicentre cross-sectional observational study. SETTING: Eleven primary care practices in Newfoundland; 10 were in a rural setting. PATIENTS: Of 110 consecutive adult patients with a supposed allergy to penicillin 97 agreed to participate in the study; 92 underwent RAST. INTERVENTIONS: Patients helped physicians complete a questionnaire and had a venous blood sample taken for the RAST. Physicians examined the clinical history and judged whether the patient was likely to have a positive RAST result. MEAN OUTCOME MEASURES: Rates of positive and negative RAST results for penicillin V and G. RESULTS: Of the 92 patients 8 had a positive RAST result and 84 a negative one. The positive predictive power of a "good" clinical history (e.g., urticaria, swollen eyes, tongue or lips, or an anaphylactic reaction witnessed by a physician) was low (10%); the negative predictive power of a "poor" clinical history (e.g., nausea, vomiting, diarrhea, fever, nonspecific rash or fainting) was 92%. CONCLUSIONS: Less than 10% of primary care patients with a supposed allergy to penicillin will have a positive RAST result. In addition, physicians'' predictions of allergy in such patients are imprecise.     

Diagnosis of penicillin allergy by skin testing: the Manitoba experience.

The reliability of skin testing in the diagnosis of penicillin allergy was studied in 86 adults and 167 children with a history of possible hypersensitivity reactions to penicillin. Skin testing was done with the major antigenic determinant of benzylpenicillin and minor determinants of benzylpenicillin, ampicillin, cloxacillin, methicillin and cephalothin. The overall frequency of positive skin reactions was 11.5%. Among the patients with positive skin reactions about half had a history of immediate or accelerated reactions to penicillins, but 2 of 11 adults and 50% of the children in this group had a history of maculopapular rash of delayed onset. There was a low frequency of positive skin reactions when there was a long interval between the times of clinical reaction and skin testing. Of 169 patients reacting negatively to skin testing who received a specific drug challenge only 2 manifested mild urticaria; this indicates the reliability of the skin tests in predicting penicillin allergy. The major and minor determinants of benzylpenicillin were the most useful reagents. One fifth of the patients with penicillin hypersensitivity would have been missed if the major determinant of benzylpenicillin alone had been used for skin testing. The additional use of the minor determinants of other penicillin derivatives, however, did not increase substantially the clinical reliability of the skin testing procedure.     

In vitro diagnosis of penicillin and streptomycin allergy. The specific leukocyte alteration reaction using luminescence microscopy]

The method of fluorescent microscopy was used for studying the diagnostic value of the reaction of the leucocyte specific alteration (LSA) in patients with different syndromes of hypersensitivity, allergy in the anamnesis and without hypersensitivity to penicillin and streptomycin. It was found that only markedly positive results of the LSA reaction (independent of the sensibilization type) were of diagnostic value, the results of the reaction being stated in half of the patient with hypersensitivity in the anamnesis and in 3/5 of the patients with allergy. Simultaneous use of other tube immunological or skin tests was recommended for the other patients with lower levels of the positive results of the LSA reaction with a purpose of etiological diagnostics or revealing latent sensibilization before treatment with the antibiotics. The LSA reaction is recommended for practical use in complex with other methods of allergological examination.     

Testing the sterility of injection preparations of penicillin series antibiotics]

The efficiency of 3 variants of the method for determination of microbial flora was compared on the injection preparation of potassium benzylpenicillin artificially infected with Staph. aureus 209P and the spores of Bac. subtilis ATCC 6633 in different doses and with different amounts of the preparation in the vials. The procedure of the preparation dissolution in the vial with the thioglycol medium containing penicillinase proved to be most effective. The microbe detection amounted to 100 per cent. The procedure was less labour- and time-consuming since addition of penicillinase to each vial with the thioglycol medium was excluded. The risk of the medium occasional infection with microbial flora during the assay was decreased.