Pre-Selection of Therapy-Naive Patients According to Source of Infection by HIV-Specialized Physicians Increases the Detection Rate of Resistance Associated Mutations.

H. Knechten, R. Ehret, F. Wiesmann and P. Braun. PZB, Aachen (Germany).

Background: Several evaluations have fond a transmission rate of HIV-resistance strains between 5 and 15%. The aim of this evaluation was to examine, if a substantiated suspicion of transmitted resistant HIV-strains by the physician is reflected in increasing incidence. Material and Methods: Eleven centres in the region Nordrhein, in Germany, participated in a period from 10/2000 to 09/2002. Prior to genotyping, the physicians were asked to specify the status of the index person and the suspected drug resistance. Resistance testing was performed for 30 patients with the open gene system from Visible Genetics/Bayer AG. Results: Primary or secondary mutations were detectable in 97% of all performed tests. The protase inhibitor (PI) secondary mutations typical for non-B subtypes or polymorphisms (e.g. K20IMR, M36I, L63PCT, A71S or V77I) were not taken into account in further interpretations. 40% (12 of 30) of patients showed resistance relevant mutations: primary mutations in the protease gene in 4 cases and reverse transcriptase relevant mutations in 10 cases. Mutations corresponding to the class of non-nucleoside reverse transcriptase inhibitors (NNRTI) were not detected. The reason stated most frequently for the suspicion of transmitting resistant strains was multiple unsafe sex (43%) with therapy-experienced persons. Specified information on former therapies of the index person was available for 13% of patients. Conclusion: Though the source of infection was known in only a few cases, resistance relevant mutations were found in 40% of therapy naïve patients studied. Consequentialy HIV-specialized physicians are able to suspect patients with transmitted resistance mutations with a higher probability than the statistical mean of 5-15%. This is a strong indication for resistance testing directly after infection or instead prior to initial therapy. To confirm these data they are going to be studied in an evaluation with a larger number of  centres and patients.