Skin tests ensure safe penicillin use
Most patients with a history of allergy to penicillin can use the drug without harmful reactions. This finding is encouraging news in view of increasing resistance to antibiotics. Approximately 10% to 20% of the patients admitted to a hospital have a history of allergic reaction to penicillin, but many do not remember the type of reaction they had.
Most who report a history of penicillin allergy routinely are placed on alternative antibiotic therapies to avoid the risk of severe reaction to penicillin. "A person with a history of penicillin allergy and a negative reaction to a skin test may be able to use a penicillin compound that could reduce the use of certain alternative antibiotics and cut down on the increasing emergence of resistant microorganisms," says Mercedes Arroliga, MD, of the pulmonary and critical care department at the Cleveland Clinic. Skin tests have a reaction rate between 0.3% and 1.2% with no serious adverse side effects. Arroliga’s comments are based on findings from a recent pilot study.1
This study suggests that skin tests are a safe, reliable method of determining the patient’s true risk of an immediate systemic allergic reaction. Arroliga adds, "When a skin test is done by personnel skilled in performing and interpreting the test, 97% of patients with negative reactions to the skin test will tolerate a penicillin compound. Penicillin skin testing can be a safe and effective strategy to reduce the use of broad spectrum antibiotics, as well as a useful strategy to modify antibiotic use."
Although the tests were conducted on patients admitted to a medical intensive care unit (MICU), according to the researchers, "this strategy can be extended to the general wards and outpatient areas." To err on the side of safety by using alternative antibiotics is understandable.
After all, it has been estimated that penicillin compounds cause most drug-mediated anaphylactic deaths in the United States. But safety has its price: Infections caused by multidrug-resistant pathogens are associated with increased severity of illness and higher mortality rates.
Despite its small sample size, the study suggests that penicillin skin tests could enhance efforts to modify antibiotic use in intensive care as well as inpatient and outpatient areas.
Here are a few highlights from the three-month penicillin skin test study, conducted from April to June, 1999:
• Of the 257 patients admitted to the MICU, 24 labeled as penicillin allergic were enrolled in the study.
• The three patients who had recent episodes of immediate reaction to penicillin, including anaphylaxis (toxic reaction), were not given the skin test.
• Of the 21 patients given the skin test, 11 did not know the type of penicillin allergy they had; six had had skin rash; and four had developed urticaria (hives or rash) when given penicillin 30 years ago.
• In 20 patients, the skin test results for penicillin were negative. In one patient, the test could not be read due to lack of skin reactivity to histamine; a later dose challenge with piperacillin was well tolerated.
• Treatment with penicillin was started in 10 of the 21 patients as a result of the negative skin test results. No side effects were reported.
Reference
1. Arroliga ME, Wagner W, Bobek MB, et al. A pilot study of penicillin skin testing in patients with a history of penicillin allergy admitted to a medical ICU. Chest 2000; 118:1,106-1,108.
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