There are many species of Bartonella, which have increased in recent years due to modern DNA analysis techniques, such as PCR and DNA hybridization . Several genera and species, formerly considered distinct, have been reclassified under the species Bartonella, such as the genus Grahamella (Spach, "Basic"). Characteristics common to Bartonella species include: Gram negative, pleomorphic morphology, slow growth, some have flagella (important virulence factor) and are fastidious (i.e. require special medium to