Method for obtaining blood culture while diagnosing bloodstream infection.

Abstract

Diagnosing of bloodstream infection (BSI) in outpatients is essential. A large blood volume is required to obtain blood culture (CLSI): 2 sets, 40ml of blood for diagnosing in 95% cases of bacteremia. Molecular-genetic methods can not replace blood culture method, but they accelerate the identification of any pathogen. Culturomics gives a combination of different conditions for isolating microorganisms from a sample and along with their genetic identification. We used the patent method for direct inoculation of buffy-coat from 4,5ml of a venous blood sample and MALDI-ToF identification method. In 382 outpatients examined there were received 183 blood cultures (48,0%), more often among women (65,6%) and young people (74,9%). The causative agents of community-acquired bloodstream infection were aerobes (73,4%), anaerobes (24,2%), fungi (2,4%). The gram-positive cocci were prevailing (51,4%) and the gram-negative rods were isolated rather seldom (9,6%). BSI was monomicrobial (66,5%) and polymicrobial (33,5%). Polymicrobial blood cultures had 2, 3, 4 agents in one blood sample (75,4%, 18,8%, 5,8%, respectively). There were also found combinations of different species of aerobes (47,8%), aerobes with anaerobes (42%). BSI caused complications of the primary disease of the respiratory system, urogenital system and in 100% of cases after plastic surgery. A small blood volume is required for buffy-coat inoculation, the direct agar culture reduces the response time to 2 days, so it makes genetic identification possible on the 2nd day from the moment of blood collection.