COMPARISON OF DIFFERENT DNA-FINGERPRINTING TECHNIQUES FOR MOLECULAR TYPING OF BARTONELLA-HENSELAE ISOLATES

Seventeen isolates of Bartonella henselae from the region of Freiburg, Germany, obtained from blood cultures of domestic cats, were examined for their genetic heterogeneity, On the basis of different DNA finger printing methods, including pulsed-field gel electrophoresis (PFGE), e nterobacterial repetitive intergenic consensus (ERIC)-PCR, repetitive extragenic palindromic (REP) PCR, and arbitrarily primed (AP)-PCR, thr ee different variants were identified among the isolates (variants I t o PII), Variant I included 6 strains, variant II included 10 strains, and variant III included only one strain. By all methods used, the iso lates could be clearly distinguished from the type strain, Houston-1, which was designated variant TV, A previously published type-specific amplification of 16S rDNA differentiated two types of the B, henselae isolates (16S rRNA types 1 and 2). The majority of the isolates (16 of 17), including all variants I and II, were 16S rRNA type 2, Only one isolate (variant III) and the Houston-1 strain (variant IV) comprised the 16S rRNA type 1, Comparison of the 16S rDNA sequences from one rep resentative strain from each of the three variants (I to III) confirme d the results obtained by 16S rRNA type-specific PCR, The sequences fr om variant I and variant II were identical, whereas the sequence of va riant III differed in three positions. All methods applied in this stu dy allowed subtyping of the isolates, PFGE and ERIC-PCR provided the h ighest discriminatory potential for subtyping B, henselae strains, whe reas AP-PCR with the M13 primer showed a very clear differentiation be tween the four variants. Our results suggest that the genetic heteroge neity of B. henselae strains is high. The methods applied were found u seful for typing B, henselae isolates, providing tools for epidemiolog ical and clinical follow-up studies.