Dynamics of hemodialysis catheter colonization by coagulase-negative staphylococci.
OBJECTIVE
Catheter colonization is a necessary but poorly characterized step in the pathogenesis of catheter-related infections. Colonization dynamics of central venous hemodialysis catheters were studied with emphasis on coagulase-negative staphylococci (CoNS) and their population genetics, antibiotic resistance, and biofilm formation. The homogeneity of CoNS colony morphotypes was evaluated.


METHODS
Prospective, longitudinal study during 1,158 catheter-days with microbiological analysis of skin swabs, weekly catheter blood and brush samples, and catheter tips.


METHODS
Hemodialysis unit of a university hospital.


METHODS
Twenty-six patients with 24 non-tunneled and 5 tunneled catheters.


RESULTS
Nineteen (65.5%) of the catheters became colonized, 17 by CoNS. CoNS colonization of the inner lumen was observed in 17.2% of the catheters and was first detectable after 3 weeks. Colonization of the outer surface occurred in 44.8% of the catheters within a minimum of 2 weeks. PFGE of 53 CoNS revealed 10 clones and 20 unique isolates. Isolates from clones were more frequent in catheter blood and brush cultures than were unique isolates (41% vs 15%), were resistant to more antibiotics (median, 7 vs 2), and tended to more often carry the icaA gene (64.1% vs 40%). Four (23.5%) of the catheters showed colonization with a mixture of CoNS based on PFGE. The time from catheter insertion to such mixed CoNS colonization was longer than that for colonization with one CoNS PFGE pattern only (42 vs 25 days).


CONCLUSIONS
Colonization of hemodialysis catheters is dominated by multidrug-resistant, icaA-positive CoNS clones. Mixed CoNS colonization occurs, but is delayed, suggesting a process of sequential superinfection.
Fux
Christoph A
CA
Institute for Infectious Diseases, University of Bern, Bern, Switzerland.
Uehlinger
Dominik
D
Bodmer
Thomas
T
Droz
Sara
S
Zellweger
Claudine
C
Mühlemann
Kathrin
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000209:etiology; D018441:Biofilms / Q000254:growth & development*; D002405:Catheterization, Central Venous / Q000009:adverse effects / Q000295:instrumentation*; D002408:Catheters, Indwelling / Q000382:microbiology*; D003030:Coagulase; D003428:Cross Infection / Q000209:etiology; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D004866:Equipment Contamination / Q000706:statistics & numerical data*; D004867:Equipment Design; D005260:Female; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D011446:Prospective Studies; D006435:Renal Dialysis / Q000009:adverse effects / Q000295:instrumentation*; D013203:Staphylococcal Infections / Q000209:etiology; D013210:Staphylococcus / Q000235:genetics / Q000254:growth & development*; D015163:Superinfection / Q000209:etiology; D013557:Switzerland; D013997:Time Factors
D003030:Coagulase; D004269:DNA, Bacterial