Combining culture techniques for Bartonella: the best of both worlds

Abstract

In this study we compared some common Bartonella culturing methodologies using four diverse species causing human illnesses. Based on a review of the literature, we focused on three major inconsistencies between protocols: base medium, cell coculture, and temperature. Our data showed that Bartonella tamiae demonstrated temperature-dependent growth limitations between common culturing conditions only 2°C apart. Additionally, growth of B. quintana was significantly enhanced by the presence of mammalian cell coculture under mammalian cell culture conditions; however, when the medium was modified to incorporate insect cell culture-based medium, coculturing with mammalian cells was no longer needed. In this study, we were able to overcome these temperature- and cell-dependent limitations and accommodate all of the strains tested by combining mammalian cell culture-based medium with insect cell culture-based medium.

Fig. 1.

Growth curves of four Bartonella species, B. tamiae, B. henselae, B. elizabethae, and B. quintana, measured at two temperatures, 35°C and 37°C. There are five conditions tested for each strain at both temperatures. ●, M10 cell-free medium; ○, M10 medium with Vero E6 cells; ■, MS10 cell-free medium; □ MS10 medium with Vero E6 cells; ▴, S10 cell-free medium.

Fig. 2.

Differences in autoagglutination between different temperatures and media after 36 h. Representative immunofluorescent micrographs of each bacterial strain grown in axenic media (M10, MS10, and S10) at both 35°C and 37°C are shown. Images were taken with a ×40 objective before the contrast was adjusted, and the images were cropped using Adobe Photoshop.