The official world record is 28. This has been done four times: Komori, Ceulemans, Forthomme, and Caudron. Runs of 31 have been reported by Sayginer, and Patino: Sayginer in practice, and Patino ran 13 and out and kept going for 18 more.
To me I think the "record" should go to Jaspers. Playing Blomdahl in the European championships a couple of years ago, in the 15 point set format, he ran 13 and out in the first set, 15 and out in the second set, and 6 from the break in the third. That's 34 in a row without a miss.