Carriage rate of Staphylococcus aureus among patients receiving allergy injections

The relative frequency of positive cultures for Staphylococcus aureus was studied among healthy young patients undergoing desensitization for allergies to determine whether the administration of repeated injections under aseptic conditions had any effect on the carriage rate of S. aureus. Three groups of patients were considered: group I, 11 patients receiving injections for the first time; group II, 20 patients already receiving injections; and group III, 20 control patients who did not receive any injections. Skin, nose and throat cultures were obtained once every two weeks for four months. Among group I patients the rate increased from 18% to 55% following the first injection, after which it fell to a 30-35% level. A rate of 25-35% was found in group II patients as compared to 15-20% in group III. Skin carriage of Staphylococcus aureus was found only among group I and group II patients. No local or systemic staphylococcal infections were found during the course of the study. The initial increase in carriage rate of staphylococcus among the healthy young adults in group I is unexplained. Thus, the results of this study further support our initial theory that regular use of needles alone increases the carriage rate of S. aureus, even under strict aseptic conditions.