Trends in Blood Culture Contamination in a Specialised Oncology Hospital: A Five-year Retrospective Observational Study
Year: 2026
Type: article
Study design: Observational Study
Abstract: Introduction: Bloodstream Infections (BSIs) are a major source of morbidity and mortality in cancer patients who are immunocompromised. While blood culture remains the gold standard for BSI diagnosis, contamination during collection can result in false-positive results, leading to unnecessary antibiotic use, prolonged hospitalisation, and increased healthcare costs. Aim: To analyse Blood Culture Contamination (BCC) rates over a five-year period in a tertiary care cancer hospital. Materials and Methods: A retrospective observational study was conducted from January 2019 to December 2023. All blood culture specimens received in the Department of Microbiology, Homi Bhabha Cancer Hospital and Mahamana Pandit Madan Mohan Malaviya Cancer Centre, Varanasi, Uttar Pradesh, India were analysed. Contamination rates were analysed annually, department-wise, and by collection site i.e., (blood collected from peripheral vs central line). Data were represented as frequencies and percentages to determine the annual contamination rates over the months. Statistical analysis was performed using the Chisquare test, with p-value <0.05 considered statistically significant. Results: Of the 2,651 positive cultures, 761 (28.7%) were identified as contaminants, corresponding to an overall contamination rate of 3.11%. Coagulase-Negative Staphylococci (CoNS) represented the predominant contaminants, with a statistically significant upward trend (p-value =0.047). A similar increase was observed for Micrococcus spp. (p-value <0.001). Higher contamination rates were observed in specimens collected from peripheral sites, particularly in the paediatric haemato-lymphoid, adult haematology, and uro-oncology departments, with statistically significant variation across the study years (p-value <0.001, p-value <0.001, and p-value =0.030, respectively). General wards: 513/13542 (3.79%) and chemotherapy: 97/3474 (2.79%) showed higher contamination rates compared to specialised units like bone marrow transplant: 12/886 (1.36%). Conclusion: Although overall contamination rates remained close to the acceptable threshold set by the Clinical and Laboratory Standards Institute (CLSI) (<3%), significant variation was observed across departments and collection methods. Targeted training, strict adherence to aseptic techniques and continuous surveillance are essential to minimise contamination, improve diagnostic accuracy, and optimise patient outcomes. BCC remains a key challenge in accurately diagnosing BSIs among oncology patients.
Language: English
Subfield: Microbiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $275
OpenAlex ID: W7223304202