VANDECASTEELE SJ, PEETERMANS WE, MERCKX R, VAN ELDERE J; Interscience Conference on Antimicrobial Agents and Chemotherapy (41st : 2001 : Chicago, Ill.).
Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2001 Dec 16-19; 41: abstract no. B-957.
Univ. Hosp., Dept. of Internal Med., Leuven, Belgium
BACKGROUND: Coagulase negative staphylococci (CNS) are the main cause of foreign body (FB) associated infections. FB associated CNS seem to behave differently from planktonic CNS. The aim of this study was to investigate housekeeping metabolic changes occurring during early in vitro FB colonisation. METHODS: S. epidermidis in exponential growth phase in broth was pelleted and suspended in NaCl 0.9 %. Segments of a polyurethane catheter were incubated at 37 degreesC in this suspension. After 10, 20 and 35 min catheters were removed and washed. RNA and DNA were instantaneously isolated from broth, suspension and catheters by a FastPrep[TM] based protocol. 1/3 of the sample was used for DNA quantification (gDNA), 2/3 were purified with the RNeasy kit (Qiagen) and DNase treated. cDNA was synthesised with MMLV. The relative expression (cDNA/ gDNA) of 16S rRNA (essential for protein synthesis), triosephosphate isomerase (tpi - glucose metabolism) and guanylate kinase (gmk - nucleic acid synthesis) was determined with Taqman quantitative PCR. RESULTS: The expression of S. epidermidis 16S was 5 to 10x higher on the catheters than in suspension (p<0.001 at 10 and 20 min, p=0.02 at 35 min) or in broth (p<0.001 - t-test). The expression of tpi did not change significantly. The expression of gmk was the same in suspension and on the catheters, but 9x higher in broth (p<0.0001). CONCLUSION: Early adhesion on foreign bodies in nutrient poor conditions induces a strong increase in 16S expression with a low gmk expression. This indicates a high protein synthesis and a low dividing rate. These findings support the hypothesis that early colonisation provokes a phase variation with major metabolic changes. The high 16S expression during early colonisation may provide an explanation for the success of minocycline-rifampin impregnated catheters in the prevention of CNS infections.
Publication Types:
Keywords:
- Catheterization
- Foreign Bodies
- Foreign-Body Reaction
- In Vitro
- Minocycline
- Polymerase Chain Reaction
- Polyurethanes
- RNA
- Rifampin
- Staphylococcus
- Staphylococcus epidermidis
Other ID:
UI: 102269658
From Meeting Abstracts