University of Southern Denmark Simplified screening in an emergency department detected methicillin-resistant Staphylococcus aureus

IntroductIon: All patients admitted to Danish hospitals are screened for methicillin-resistant Staphylococcus aureus (MRSA) by a questionnaire consisting of 19 questions issued by the Danish Health and Medicines Authority (DHMA). This study aimed to evaluate which of the questions were most useful. Furthermore, we assessed if other questions were more adequate and if a simplified screening model would perform equal to or better than the one presently used. Methods: Swabs were obtained for MRSA culture from patients who were more than ten years old and who had been admitted to an emergency department (ED). All DHMA questions together with a range of additional questions were answered. results: Among the 1,220 patients who participated, 0.9% were MRSA carriers. Only three DHMA questions were associated with a significant risk of MRSA carriage. The additional questions associated with MRSA were “stayed with a non-Danish family within the past three years” and “daily contact with children at a nursery or kindergarten”. A new model with only five questions increased the sensitivity insignificantly from 18-55% to 73% in the revised model, whereas no changes were seen for specificity, predictive values or likelihood ratios. conclusIons: The DHMA’s targeted screening for MRSA detection contained only few questions with significant association to MRSA carrier stage. A model based on only five questions seems to insignificantly improve the MRSA screening in this population. In order to develop a more simple and effective screening model, we recommend that our findings be tested in another ED patient population. FundIng: Southern Jutland Hospital funded this study. trIal regIstratIon: not relevant. The burden of methicillin-resistant Staphylococcus aureus (MRSA) varies between countries. In Denmark, the prevalence has increased in the past decade [1]. New MRSA strains have been identified which are associated with pig farming [2], but many other strains have been isolated as well, suggesting that there are multiple sources of community-acquired MRSA [3]. Since the majority of patients who are admitted to hospital pass through the emergency departments (ED), the EDs play a crucial role in early identification of MRSA carriers. All patients admitted to Danish hospitals are screened for exposure to MRSA by a questionnaire issued by the Danish Health and Medicines Authority (DHMA) [4]. The questionnaire consists of a mandatory section to be used for all admissions with four main questions and five sub-questions addressing common risk situations, a section used in special risk situations (five questions) and five individual risk factors; a total of 19 variables are to be checked if the full screening procedure is followed. The procedure is quite complex, it requires some instruction and is time-consuming. In a recent ED study, we used this questionnaire approach and found a 0.9% MRSA prevalence, and we were able to identify 18-27% of the MRSA carriers if the mandatory general risk questions were answered, and up to 55% of the MRSA carriers if all the general risk, specific risk and individual risk questions were answered. Only 9% of the MRSA carriers would be isolated using the DHMA isolation recommendations. The ED study also revealed that the majority of MRSA clones originated from pigs and Northern Germany, which reflects the fact that the ED was situated only 25 km from the Danish-German in a rural area with several pig farms [5]. The DHMA screening questionnaire was based on the knowledge of an established range of known risk factors for MRSA acquisition, such as contacts to local outbreaks or other MRSA carriers, travelling and nonDanish origin, or skin diseases [6, 7]. Acknowledging that the majority of MRSA cases in our study derived from pigs and Northern Germany, we hypothesised that a minor part of the DHMA questions together with other additional questions more targeted to these risk factors for MRSA would detect the MRSA carriers to the same or at a higher extent than the currently used DHMA screening. The aim of the present study was: first, to evaluate which of the 19 questions in the DHMA screening were most useful for detecting MRSA; second, to analyse if other questions regarding MRSA exposure would perform better than the ones currently included in the screening; and third, if a more simplified screening model combining the most accurate questions for detection of MRSA risk would perform equally to or better than the presently used DHMA MRSA screening in this area of Denmark. simplified screening in an emergency department detected methicillin-resistant staphylococcus aureus Christian Backer Mogensen1, Poul Kjældgaard2, Charlotte Jensen1 & Ming Chen2