This study examined 178 Bartonella henselae isolates from 9 countries. Bacteria were isolated from cats, humans, and a dog in European, American, Asian, and Australasian populations. Two major genotypes have been described in the literature based on distinct 16S ribosomal DNA differences. Globally, genotype I has typically been identified in humans and genotype II in cats. Most B henselae sequences segregate into these genotypic groups. A new technique called multiple-locus variable-number tandem-repeat analysis (MLVA) was recently applied to Bartonella typing with good results; this study used the technique to examine variable-number tandem repeats (VNTRs). A total of 99 MLVA profiles were identified, and profiles were detected in a single strain or isolate (n = 69) or in > 1 isolate (n = 30). No profiles were shared by both genotypes I and II, and both genotypes were diverse, as determined by the diversity index. Profiles appeared to be location-specific, but there was no obvious dominance of a specific profile in a single continent. Genotype I profiles were significantly associated with human-specific profiles. Group A profiles included exclusively genotype II feline isolates, whereas all human isolates segregated into group B profiles.

COMMENTARY: It is notable that no profiles were shared between genotypes I and II, because such genotyping may help confirm origin of infection and transmission between cats and humans. Species-
specific profile differences suggested that genotype I profiles could be associated with greater pathogenicity in humans, particularly in group B, and MLVA for the VNTR region might serve as a biomarker for human transmission.—Indu Mani, DVM, DSc (infectious disease)

Molecular epidemiology of feline and human Bartonella henselae isolates. Bouchouicha R, Durand B, Monteil M, et al. EMERG INFECT DIS 15:813-816, 2009.