Clinical significance of coagulase-negative staphylococci

Although coagulase-negative staphylococci (C-NS) have been implicated in certain human infections, they are generally regarded as contaminants, and their clinical significance is questioned. To assess their role as pathogens, we studied 205 isolates of C-NS from wounds and body fluids (blood, urine, pleural and peritoneal fluids, etc.). Patient's charts were reviewed, and, by using strict criteria, a determination was made regarding the clinical significance of these isolates. The organisms were then identified to determine whether certain species of C-NS were associated with specific infections. S epidermidis sensu stricto accounted for 81% of the C-NS isolated. The frequencies of other species were: S. haemolyticus (6%), S. hominis (5%), S. capitis (4%), S. warneri (3%), and others (1%). Only two isolates were novobiocin resistant; neither was identified as S. saprophyticus. By using our criteria, 22% of the C-NS were considered to be clinically significant, and the majority of these (93%) was S. epidermidis. The most common source of the clinically relevant C-NS isolates was wounds. These data suggest that identification of C-NS species other than S. epidermidis may be of limited value in predicting clinical significance.