Detection of Bartonella henselae DNA by two different PCR assays and determination of the genotypes of strains involved in histologically defined catscratch disease

Cat scratch disease (CSD) is a common cause of subacute regional lymphadeno pathy, not only in children but also in adults. Serological and molecular s tudies demonstrated that Bartonella henselae is the etiologic agent in most cases of CSD. Amplification of B. henselae DNA in affected tissue and dete ction of antibodies to B. henselae are the two mainstays in the laboratory diagnosis of CSD. We designed a retrospective study and investigated formal in-fixed, paraffin-embedded lymph nodes from 60 patients (25 female, 35 mal e) with histologically suspected CSD by PCR amplification. The sensitivitie s of two different PCR assays were compared. The first primer pair amplifie d a 296-bp fragment of the 16S rRNA gene in 36 of the 60 samples, correspon ding to a sensitivity of 60%. The second primer pair amplified a 414-bp fra gment of the htrA gene in 26 of the 60 lymph nodes, corresponding to a sens itivity of 43.3%, Bartonella DNA could be detected in a total of 39 (65%) o f the 60 lymph nodes investigated. However, histopathologic findings are ty pical but not specific for CSD and cannot be considered as a "gold standard " for diagnosis of CSD. The sensitivity of the PCR assays increased from 65 to 87% if two criteria (histology and serology) were used in combination f or diagnosis of CSD, Two genotypes (I and II) of B. henselae are described as being involved in CSD, Genotype I was found in 23 (59%) and genotype II was found in 9 (23%) of the 39 PCR-positive lymph nodes. Seven (18%) lymph nodes were negative in both type-specific PCR assays. Thirty (50%) of our 6 0 patients were younger than 20 years old (15 were younger than 10 years), 20 (33%) were between 21 and 40 years old, and 10 (17%) patients were betwe en 41 and 84 years old. Our data suggest that detection of Bartonella DNA i n patients' samples might confirm the histologically suspected diagnosis of CSD.