Comparison of growth and morphology of Borrelia burgdorferi sensu lato in BSK-H and BSK-II media stored for prolonged periods

Abstract

Barbour-Stoenner-Kelly II (BSK-II) and BSK-H media were used for cultivation and isolation of fastidiousBorreliaspecies - the causative agents of Lyme borreliosis. Culture media have a limited shelf life and require adequate storage. Our goal was to assess how the growth ofBorreliawould be affected by prolonged storage of media and inadequate storage conditions (BSK-H stored at +4 degrees C for 2.5 years and BSK-II stored at -20 degrees C for 11 years). Growth of differentBorrelia afzelii,Borrelia garinii,Borrelia lusitaniaeandBorrelia valaisianastrains was assessed during 2 weeks of incubation at 33 degrees C. Monitored parameters included cell count per mL, morphology and motility. The results of this study have shown weaker growth of borrelia strains in BSK-H at +4 degrees C (median final cell number of 1.5 x 10(6)/mL) than in BSK-II at -20 degrees C (median final cell number of 7.75 x 10(6)/mL) and in fresh BSK-H media (median final cell number of 8.95 x 10(6)/mL). Duration of storage of media had no impact onBorreliamorphology and motility. Our results indicate that temperature of -20 degrees C is optimal for long-term storage of medium, BSK-II stored for 11 years provided effective support to growth ofBorreliaand may be employed for cultivation.