Colonization and molecular epidemiology of coagulase-negative Staphylococcal bacteremia in cancer patients: A pilot study

Background: Controversy surrounds the source (skin vs mucosa) of coagulase-negative staphylococci (CoNS) bacteremia in cancer patients. Determining the source of this infection has clinical and epidermologic implications. Objective: To determine the source(s) of CoNS bacteremia in cancer patients. Methods: Between November 1998 and October 2000, cultures of nasal and rectal mucosa and skin at central venous catheter (CVC) sites were obtained in 62 patients (66 episodes) with CoNS-positive blood culture(s). Bacteremia was classified as true, indeterminate, or unlikely on the basis of clinical and microbiologic findings. Molecular relatedness of strains isolated from the blood and from colonized sites of patients with true and those with unlikely bacteremia was examined using pulsed-field gel electrophoresis (PFGE). Results: CoNS colonization was present in 55 episodes (83%). The nasal mucosa was the most frequently colonized site (86%), followed by rectal mucosa (40%) and skin at site of CVC insertion (38%) (P < .001). Colonization at >= 1 site was common. True and unlikely bacteremia accounted for 11 and 10 episodes, respectively, with the remaining 45 episodes considered undetermined or had negative surveillance cultures. Among patients with true bacteremia, 6 mucosal isolates and only 1 skin isolate were related by PFGE to the blood isolate recovered from the same patient. Conclusion: Mucosa is the most common site of CoNS colonization and is the likely source of CoNS bacteremia in cancer patients.