The population structure of Bartonella henselae was analysed by different typing methods. For the present work multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were used for analysing the genetic diversity and population structure of 182 B. henselae isolates. Both methods have been shown to exhibit a high discriminatory power and were chosen as appropriate techniques for the molecular typing of different B. henselae strains.
In summary, it can be said, that the restriction enzymes SmaI, ApaI, Eco52I und XmaJI are particularly appropriate for PFGE analyses. In contrast, the enzyme NotI seems unsuitable for B. henselae typing, because of the observed restriction patterns, which conduct to 13 different PFGE types within 182 isolates.
Through sequencing of the 16S rRNA gene and eight different housekeeping genes, 14 sequence types within the B. henselae population were identified. The sequence types ST1, ST5, ST6 and ST7 represent with 83,5% the main sequence types. Geographical considerations indicate a significant distribution for the sequence types ST1, ST6 und ST7. Further it was shown, that ST1 significantly comprises plenty of human pathogen B. henselae isolates. About 66% isolates associated with humans have been assigned to this sequence type. Thus, ST1 combines particularly virulent strains. The comparison of PFGE results obtained in this study with MLST results led to a high concordance between PFGE types and sequence types.
Genetic variants, which represent one genetic main type after a lot of passages, were demonstrated by analysing B. henselae primary isolates. The mechanism of these changes, which had been reflected by PFGE restriction patterns, is still unknown. Our data indicate for the first time that a few B. henselae isolates possess two different 16S rRNA gene copies. In future, the existence of different 16S rRNA gene copies should be considered in analysing 16S rRNA sequencing results.
Concluding, it is to notice that the combination of PFGE and MLST is recommendable for further epidemiological studies of B. henselae.