Quantitative detection of bacterial
DNA in whole blood
in bloodstream infection
INGRID ZIEGLER
Medical Science with a specialisation in Medicine
Örebro Studies in Medicine 183 I ÖREBRO 2018
ÖREBRO STUDIES IN MEDICINE 183 2018ING
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ingrid ziegler was born in Uppsala in 1976. After studies at the Medical School of Uppsala University, she obtained the Medical Degree in 2003. Thereafter, she moved to Örebro for Internship, followed by an Infectious Diseases Residency at Örebro University Hospital. She accomplished the Specialist Degree in 2011, and is currently working as an Infectious Diseases Specialist at the Department of Infec-tious Diseases at Örebro University Hospital. The research work presented in this thesis started in 2011 with Associate Professor Kristoffer Strålin as a supervisor.
Sepsis is the body’s dysregulated and life-threatening response to an infec-tion. The infectious pathogen in sepsis is often spread into the bloodstream, causing a bloodstream infection. Today, blood culture is the standard diag-nostic method to detect a bloodstream infection. However, blood culture has several limitations, such as a long time to result and suboptimal sensitivity. With better methods for rapid detection of the causative pathogen, more sepsis patients would get early, appropriate antimicrobials. This would have beneficial consequences, not only in terms of patient survival, but also for the global problem of antibiotic resistance. By molecular methods, such as PCR, pathogen DNA can be detected within hours. In addition, PCR enables quantification of the DNA, which might be useful in sepsis management for indication of infection severity and treatment response.
This thesis aims to increase the knowledge on how quantitative PCR can be used in the diagnostics of bloodstream infections. In the studies presented in the thesis, different PCR methods were used, both commercial and in-house assays, for analyses of blood samples from patients at the Emergency De-partment. We found that high amounts of bacterial DNA in the bloodstream were associated with inflammation, presence of sepsis, and mortality, while low amounts of bacterial DNA often were due to contamination bacteria.
issn 1652-4063 isbn 978-91-7529-257-1
