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Risk factors for blood culture contamination in a tertiary hospital: a one-year retrospective analysis

Year: 2026

Type: article

Abstract: BACKGROUND: Blood culture contamination is a significant problem that can lead to misdiagnosis, unnecessary antibiotic use, and increased workload. This study aimed to determine the blood culture contamination rates in a tertiary hospital and to evaluate the factors associated with contamination. METHODS: This retrospective descriptive study included blood culture samples collected at a tertiary hospital between January 2023 and December 2023. Cultures from patients aged ≥ 18 years were evaluated. Growth of coagulase-negative staphylococci (CoNS) and other skin flora agents that were not considered clinically significant were classified as contamination. Contamination risk factors, including the sampling unit, sampling period, and healthcare personnel who collected the cultures, were evaluated. RESULTS: A total of 7716 blood cultures from 2388 patients were included. 11.8% of the cultures were defined as contaminated. Contamination rates were found to be significantly higher in internal medicine wards (12.5%) and intensive care units (13.5%) compared to surgical wards (3.6%) (p < 0.001). In logistic regression analysis, the risk of contamination was found to be 3 times higher in blood cultures taken from internal medicine wards and 4.1 times higher in ICUs compared to surgical wards (p < 0.001 and p < 0.001, respectively). Blood cultures obtained by intern doctors (sixth-year medical students) were independently associated with contamination (OR = 1.68; p < 0.001). The risk of contamination was higher in blood cultures taken between July and December (OR = 1.23; p = 0.004). CONCLUSION: Blood culture contamination is a multifactorial problem influenced by factors such as the sampling unit and staff experience. These findings highlight the need for targeted quality improvement interventions, particularly structured training for newly rotating clinical staff. CLINICAL TRIAL REGISTRATION: Not applicable.

Source: BMC Infectious Diseases

DOI: 10.1186/s12879-026-12945-z

Authors: Tuba İlgar, Aybegüm Özşahin

Institution: Recep Tayyip Erdoğan University

Language: English

Topic: Bacterial Identification and Susceptibility Testing

Subfield: Clinical Biochemistry

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $3,090