[Bacteremia and pseudobacteremia caused by coagulase-negative Staphylococcus in children]

To compare patients with Coagulase Negative Staphylococcus bacteremia (CoNS-B) and pseudobacteremia (CoNS-PB) in a pediatric hospital.

Descriptive and comparative study between children diagnosed with CoNS-B and CoNS-PB.

A total of 159 children with CoNS positive blood cultures were evaluated. 66 children were classified as CoNS-B (41.5%) and 93 as CoNS-PE3 (58.5%). On the average CoNS was isolated on day 21 among children with bacteremia (B) and on day 2 in those with PB (p < 0.01). Excluding newborns, patients with B and PB had on average 2.6 and 1.1 positive cultures respectively. Most children with bacteremia were at the intensive care unit (67.2%), while patients with PB were mostly detected at the emergency room. Using logistic regression analysis, we found four factors independently associated with CoNS bacteremia: total parenteral nutrition (OR 5.4; 95% CI 2.2-12.9), low birth weight (OR 2.6; 95% CI 1.1-5.9), catheters placed by cut-down technique (OR 1.9; 95% CI 1.1-3.8), and inmuno-compromised patients (OR 2.7; 95% CI 1.1-6.7). Resistance to oxacilin was reported in 71.7% of the CoNS isolated. The overall mortality associated to CoNS-B was 6%. Among children with CoNS-PB, 10% received antibiotics, half of them vancomycin.

These results show that CoNS-B occurs mainly as a nosocomial episode. CoNS-PB more likely resulted from specimen contamination at collection, being responsible for almost 60% of all positive blood cultures. The false-positive results caused unnecessary administration of antibiotics in a significant proportion of CoNS-PB events and have a potential impact upon the emergence of resistant pathogens.