Blood Culture Contaminants in a Paediatric Population Retrospective study from a tertiary hospital in Oman

Area of Science:

• Medical Microbiology
• Clinical Diagnostics
• Paediatric Infectious Diseases

Background:

• Blood cultures are crucial for identifying pathogens and guiding antibiotic therapy in febrile children.
• False-positive blood cultures can result in unnecessary hospitalizations, antibiotic prescriptions, and further diagnostic tests.
• Accurate interpretation of blood cultures is vital for appropriate patient management in paediatric settings.

Purpose of the Study:

• To evaluate the impact and characteristics of false-positive blood cultures in a paediatric population at a tertiary hospital in Oman.
• To assess the utility of C-reactive protein (CRP) levels in differentiating true-positive from contaminated blood cultures in children.
• To identify factors associated with true-positive versus contaminated blood cultures in paediatric patients.

Main Methods:

• A retrospective study was conducted on 225 children under 13 years old with positive blood cultures at Sultan Qaboos University Hospital, Oman (July 2011 - December 2013).
• Blood cultures were reviewed to classify them as true-positive or contaminated.
• Clinical data, including patient demographics, hospital admissions, length of stay, antibiotic prescriptions, comorbidities, mortality, and laboratory markers (WBC, ANC, CRP), were analyzed.

Main Results:

• Out of 344 positive blood cultures, 53.8% were true-positive and 46.2% were contaminated.
• Coagulase-negative Staphylococcus (CONS) was the most common isolate in both true-positive (26.5%) and contaminated (67.9%) cultures.
• Children with contaminated cultures were younger, while those with true-positive cultures had higher hospital admission rates, longer stays, more antibiotic use, and increased chronic illness and mortality. White blood cell and absolute neutrophil counts were higher in true-positive cases, but CRP levels showed no significant difference.

Conclusions:

• C-reactive protein (CRP) levels are not a reliable biomarker for distinguishing true-positive from contaminated blood cultures in paediatric patients.
• A dedicated and well-trained phlebotomy team is essential for reducing blood culture contamination rates in paediatric populations.
• Minimizing false-positive results through improved collection techniques can prevent overtreatment and reduce healthcare costs.