During the past week, three out of four blood cultures from a febrile neonate in...

The scenario involves a febrile neonate in an intensive care unit (ICU) with three out of four blood cultures growing coagulase-negative staphylococci (CoNS) over the past week. The Certification Board of Infection Control and Epidemiology (CBIC) emphasizes accurate interpretation of microbiological data in the "Identification of Infectious Disease Processes" domain, aligning with the Centers for Disease Control and Prevention (CDC) guidelines for healthcare-associated infections. Determining whether this represents a true infection, contamination, colonization, or laboratory error requires evaluating the clinical and microbiological context.

Option B, "Contamination," is the most likely indication. Coagulase-negative staphylococci, such as Staphylococcus epidermidis, are common skin flora and frequent contaminants in blood cultures, especially in neonates where skin preparation or sampling technique may be challenging. The CDC’s "Guidelines for the Prevention of Intravascular Catheter-Related Infections" (2017) and the Clinical and Laboratory Standards Institute (CLSI) note that multiple positive cultures (e.g., two ormore) are typically required to confirm true bacteremia, particularly with CoNS, unless accompanied by clear clinical signs of infection (e.g., worsening fever, hemodynamic instability) and no other explanation. The inconsistency (three out of four cultures) and the neonate’s ICU setting—where contamination from skin or catheter hubs is common—suggest that the positive cultures likely result from contamination during blood draw rather than true infection. Studies, such as those in the Journal of Clinical Microbiology (e.g., Beekmann et al., 2005), indicate that CoNS in blood cultures is contaminated in 70-80% of cases when not supported by robust clinical correlation.

Option A, "Laboratory error," is possible but less likely as the primary explanation. Laboratory errors (e.g., mislabeling or processing mistakes) could occur, but the repeated growth in three of four cultures suggests a consistent finding rather than a random error, making contamination a more plausible cause. Option C, "Colonization," refers to the presence of microorganisms on or in the body without invasion or immune response. While CoNS can colonize the skin or catheter sites, colonization does not typically result in positive blood cultures unless there is an invasive process, which is not supported by the data here. Option D, "Infection," is the least likely without additional evidence. True CoNS bloodstream infections (e.g., catheter-related) in neonates are serious but require consistent positive cultures, clinical deterioration (e.g., persistent fever, leukocytosis), and often imaging or catheter removal confirmation. The febrile state alone, with inconsistent culture results, does not meet the CDC’s criteria for diagnosing infection (e.g., at least two positive cultures from separate draws).

The CBIC Practice Analysis (2022) and CDC guidelines stress differentiating contamination from infection to avoid unnecessary treatment, which can drive antibiotic resistance. Given the high likelihood of contamination with CoNS in this context, Option B is the most accurate answer.