Feedback on difficulties raised by the interpretation of serological tests for the diagnosis of Lyme disease.

We had for objectives: i) to evaluate the accuracy of serologic testing for Lyme borreliosis performed in a private medical laboratory (PML); ii) to evaluate the impact of these tests on the practices of infectious diseases specialists (IDS).This study was performed in two steps: i) retrospective study of patients followed in a university hospital infectious diseases outpatient clinic for suspected Lyme borreliosis, tested (ELISA and Western blot) by both the PML and the National Reference Center (NRC); ii) national survey on IDS practices concerning patients consulting for suspected Lyme borreliosis.Between July 2008 and July 2011, 128 patients consulting for suspected Lyme borreliosis were tested by both laboratories. Serological tests came back positive in 91% of cases from the PML versus 8% of cases from the NRC. Lyme borreliosis was the IDS's final diagnosis for 3.6% of patients. The survey on practices revealed that: i) the modal duration of consultation for suspected Lyme borreliosis was 30-60 minutes; ii) for 33% of patients, serologic test results performed at the PML were the only reason to suspect Lyme borreliosis; iii) 60% of patients had no indication for antibiotics.The serological test performed in the PML were positive most of the time, but were not confirmed by tests performed at the NRC. This discrepancy lead to multiple and prolonged consultations in infectious diseases clinics, and discordance in the indications for antibiotics.