Abstract

Objective: We aimed to evaluate the patient factors which increase the probability of achieving a positive blood culture, distribution of microorganisms grown, and to reveal the impact of various factors during collection of blood on blood culture positivity.

Methods: Blood cultures of patients with a body temperature of ≥38°C and compatible with a clinical sepsis definition of Centers for Disease Control and Prevention sent to the clinical microbiology laboratory were evaluated. In this prospective case-control study, patients who had a positive blood culture composed case group, and culture-negative ones formed control group. Relationship between blood culture positivity and factors such as gender, being ≥65 years old age, presence of a chronic illness, a urinary or central venous catheter (CVC), immunosuppression, antimicrobial therapy, hospitalization and its duration in both groups were evaluated. Furthermore, antimicrobial use during blood collection, puncture site for blood collection, inoculum volume of bottles in a blood culture set, and time to positivity after blood inoculation into culture bottles were recorded.

Results: A total of 251 patients with clinical sepsis were included in the study. 122 patients fell into case group, and 129 patients fell into control group. Mean blood inoculum volume for bottles in a blood culture set was 11.45±4.4 mL in case group, whereas it was 12.3±3.8 mL in control group (p=0.122). In multivariate analyses, patients with an indwelling CVC, a chronic illness, and blood collection from different peripheral veins simultaneously or in 5- or 10-minute intervals were more likely to have positive blood cultures 2.5, 2.4 and 6.8 times, respectively.

Conclusions: Blood cultures drawn from patients with fever, particularly in the presence of CVC and chronic illness, are crucial in terms of establishing causative agents and arranging rational antimicrobial therapy. Also, it is remarkable that drawing blood from different peripheral veins simultaneously or in 5- or 10-minute intervals shortens the time to start empirical antimicrobials. Moreover, it is possible to consider a reduction in the incubation period of blood cultures from 10 days to eight days, if there is no suspicion of fastidious agents or presence of particular patient groups.

Cite this article as: Bolukçu S, Başaran S, Çağatay A, Özsüt H, Eraksoy H. [Prospective assessment of blood cultures which were sent to the clinical microbiology laboratory]. Klimik Derg. 2018; 31(2): 120-4. Turkish.