Comparison of molecular methods for Bartonella henselae detection in blood donors

Abstract

The Bartonella genus consists of neglected pathogens associated with potentially transfusional-transmitted and fatal human diseases. We aimed to evaluate Bartonella sp. prevalence in 500 blood donors and compare the results with the data already published about these samples. We used molecular diagnostic methods to detect Bartonella sp.-DNA from blood and liquid culture samples: (A) conventional PCR for two gene regions, the ITS targeting the genus Bartonella and the specific gltA Bartonella henselae; (B) nested PCR for the ftsZ gene and (C) qualitative real-time PCR for the gltA gene, both B. henselae specific. We obtained 30/500 (6%) DNA detections from the blood samples; 77/500 (15.4%) DNA detections from liquid culture samples and five (1%) samples had DNA detection from both. In total, we detected B. henselae DNA from 102/500 (20.4%) donors. The samples used in this study had already been submitted for Bartonella sp.-DNA detection using only a conventional PCR in liquid culture. Sixteen samples (3.2%) were positive previously, and from these 16 samples, 13 were negative in the new investigation. We concluded that the use of liquid culture combined with different molecular tests increases the possibility of detecting Bartonella sp.-DNA, but the tests do not avoid false-negative results. More than a fifth of blood donors had at least one PCR that detected Bartonella sp.-DNA among the eight molecular reactions performed now (four reactions in whole blood and four in liquid culture). Seven percent had B. henselae-DNA detection for two or more distinct regions. Considering the results obtained previously, the DNA of Bartonella spp. was detected or the agent isolated in 23% of analyzed blood donors. The results establish that the low bacteremia and the fastidious characteristics of the bacterium are challenges to laboratory diagnosis and can make it difficult to confirm the infection in patients with bartonelloses.

Author summary

Bartonella are bacteria that can infect humans and cause fatal diseases. They can cause chronic infection and can potentially be transmitted by transfusion since they infect red blood cells. They are difficult to cultivate in a laboratory, and they are present in low numbers in blood. There is no laboratory test that is sufficiently sensitive to detect them. To compare several laboratory diagnostic tests, we searched for these bacterial DNAs in blood and in microbiological liquid cultures of 500 blood donors. We used diverse molecular techniques and then compared the results with the previously published project. We concluded that the use of liquid culture combined with different molecular tests increases the possibility of detecting Bartonella sp.-DNA, but the tests do not avoid false-negative results. We found Bartonella henselae DNA in the blood of at least one in five donors. Hemovigilance programs are unlikely to contribute substantially to the identification of chronic posttransfusion infections since they are designed to identify well-defined acute outcomes, so it is urgent to review B. henselae transfusional risk of transmission and Bartonella sp. infection diagnosis in donors and in patients.