Development of a Rapid, Highly Sensitive Digital Drop PCR Assay for the improved diagnosis of Bartonella Infective Endocarditis

Abstract Bartonella species are slow growing intracellular bacteria that infect a variety of mammalian hosts including companion animalsproduction animalswildlifeand humansBartonella infection occurs via arthropod vectorsanimal bites and possibly inhalationBartonellosis is associated with many human diseases including infective endocarditisIEinfection of the interior of the heart including the heart valvesIE has maintained a highinhospital mortality rate offor over two decades and the number of human cases of Bartonella IE has been increasing at a rate ofannually in the US sinceBartonella species are well known for the very lowlevels of bacterial concentrations associated required for diseaseThis property presents a significant diagnostic challengeCurrent assay strategies are not up to the task of detecting Bartonella in these patientscreating an urgent need for a highly sensitive and rapid assay for the diagnosis of BartonellosisThrough the work in this proposalwe will leverage our experience in the culturing and molecular detection of bartonellosis to develop an improved Bartonella PCR assay using highly sensitive droplet digital PCRddPCRto allow the more rapidsensitiveand quantitative diagnosis of BartonellosisWe will accomplish this goal with the following Specific AimsSpecific AimDevelop and optimize a highly sensitive ddPCR assay for the diagnosis of bartonellosisDroplet digitalddPCR is a relatively new technology with a demonstrated utility in the field of quantitative infectious disease diagnosticsIt is far more sensitive than standard PCR methodsenabling the accurate quantification of rare targetsand is less susceptible to interference from other molecules in the sampleTogetherthese properties make the technology ideal for the detection of Bartonella in blood and heart tissueSpecific AimCompare ddPCR specificity and sensitivity to the gold standard method ofday BAPGM enrichment followed by PCRWe will compare ddPCR to our gold standard for Bartonella detection regimenthe culture of blood in BAPGM followed by conventional PCR detectionWe anticipate that use of ddPCRmaximized for sensitivitywill negate the need for extended culture to detect Bartonella and provide physicians with rapidactionable results within daysrather than weeksSpecific AimConfirm ddPCR sensitivity using highly concentrated blood samplesOne of the significant advantages of ddPCR over standard PCR is the reduction of amplification inhibition by foreign substanceswhich includes the inherently high amounts of competing host DNA in patient samples that are known to decrease the sensitivity of conventional PCR for low level infectionsThrough this aimwe will establish ddPCR sensitivity using concentrated DNA from blood samples that we believe will further circumvent the need for a blood culture to achieve a positive PCR resultDevelopment of this rapidhighly sensitive and specific bartonellosis clinical diagnostic tool will result in an actionablecost effective diagnostic assay for physiciansAt the current timethere are no SBIR funded projects addressing this gap in the bartonellosis diagnostic spaceProject Narrative Bartonella species are slow growingfastidiousfacultative Gram negative intracellular bacteria that infect a variety of mammalian hosts via arthropod vectors and are known to be associated with a number of human diseasesOne of the most important of these diseases is infective endocarditisIEwhich demonstrates severe mortalityWith this submissionGalaxy Diagnostics proposes the development of a novel diagnostic assay to meet the urgent need for improved serological tests for the diagnosis and monitoring of heart diseaseand otherpatients for bartonellosis