Bartonella koehlerae , a New Cat-Associated Agent of Culture-Negative Human Endocarditis

Abstract

ABSTRACT Bartonella koehlerae is reported for the first time to be a human pathogen that causes culture-negative endocarditis. It is also shown that this species, isolated twice before from domestic cats, can be recovered as well from a stray cat population in Israel. This work follows a recent report of the same case in which the causative agent was misidentified as B. henselae , based on serology and PCR-restriction fragment length polymorphism (RFLP) analysis (A. Schattner, O. Zimhony, B. Avidor, and M. Gilad, Lancet 361:1786, 2003). B. koehlerae was identified in the valvular tissue of an endocarditis patient by DNA sequencing of the PCR products of two Bartonella genes: the genes for citrate synthase ( gltA ) and riboflavin synthase ( ribC ). The commonly used PCR-RFLP analysis of the TaqI-digested gltA PCR product did not distinguish between B. koehlerae and B. quintana or between B. elizabethae and B. clarridgeiae . PmlI digestion of the gltA amplification product failed to differentiate between B. quintana , B. clarridgeiae , and B. elizabethae . RFLP analysis of the heat shock protein ( htrA ) gene by TaqI digestion misidentified B. koehlerae as B. henselae . However, RFLP analysis of the ribC PCR product, digested with TaqI, was able to distinguish between the human endocarditis-associated Bartonella species tested, B. henselae , B. quintana , B. elizabethae , and B. koehlerae , as well as between the cat-associated Bartonella species, B. henselae and B. clarridgeiae . Given the expanding number of Bartonella species emerging as human pathogens, it is suggested that PCR-RFLP analysis for the diagnosis of Bartonella infections target several genes and be coupled with DNA sequencing to avoid species identification.