Coagulase-NegativeStaphylococcus, Catheter-Related, Bloodstream Infections and their Association with Acute Phase Markers of Inflammation in the Intensive Care Unit: An Observational Study

Abstract

OBJECTIVE: To examine the relationship between the isolation of coagulase-negativeStaphylococcusin blood cultures and acute phase markers of inflammation.METHODS: The present study was a prospective observational analysis conducted at three medical/surgical intensive care units (ICUs) involving adult patients with an expected ICU stay of more than 24 h duration.RESULTS: Of the 598 patients enrolled, 573 developed suspected bloodstream infection and 434 (72.6%) had blood cultures sent 24 h after ICU admission; 142 were excluded due to positive cultures from other sites. Of the remaining 292 patients, 31 (10.7%) grew coagulase-negativeStaphylococcus, 59 (20.2%) grew known pathogenic organisms and 202 (69.2%) did not grow any organisms in their blood cultures. Twenty-five patients without suspicion of infection served as the control group. Interleukin (IL)-6, procalcitonin (PCT) and C-reactive protein (CRP) levels were highest among the known pathogen group (IL-6 271.8 U/L, PCT 4.6 U/L and CRP 164 mg/L), were similar between the coagulase-negativeStaphylococcusand negative culture groups (IL-6 67.0 U/L versus 61.4 U/L [P=1.00]; PCT 1.0 U/L versus 0.9 U/L [P=0.80]; and CRP 110 mg/L versus 103 mg/L [P=0.75]), and were lowest in the control group (IL-6 31.0 U/L, PCT 0.2 U/L and CRP 41.0 mg/L). In the coagulase-negativeStaphylococcusgroup, patients who died by day 28 had increased inflammatory bio-marker levels compared with survivors, although the differences were not statistically significant.CONCLUSIONS: Coagulase-negativeStaphylococcusisolated from blood cultures were associated with lower levels of inflammation compared with bloodstream infections due to known pathogens and were comparable with levels in patients with negative cultures.