VANDECASTEELE SJ, VAN ELDERE J, MERCKX R, PEETERMANS WE; Interscience Conference on Antimicrobial Agents and Chemotherapy (42nd : 2002 : San Diego, Calif.).
Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2002 Sep 27-30; 42: abstract no. D-2012.
Univ. Hosp., Leuven, Belgium
BACKGROUND: Quantitative catheter culture (QCC) is the gold standard for diagnosing catheter infections. This study explores the effect of teicoplanin (teico) and rifampin (rifa) on QCC by comparing it with a new method based on quantitative PCR (QPCR). METHODS: 368 catheter segments (cath) (7 mm) were inoculated with Staph. epidermidis and implanted subcutaneously in rats. For 144 and 136 cath, rats received respectively rifa (25 mg/kg/12h) or teico (50 mg/kg/12h) for 2 doses 2 days before explantation. 88 cath received no antibiotics (controls). All cath were removed at 2 weeks. 172 cath were sonicated and quantitatively cultured. Cultures were counted after 1 and 2 days. mRNA (indicating viable bacteria) and DNA were extracted from 196 cath and quantified for the gmk gene as previously described (BBRC 2002;291;528). RESULTS: At day 1, most CFU (colony forming units) in the teico and rifa group were very small and difficult to count. At day 2, 2/32 (controls), 13/68 (teico) and 4/72 (rifa) cath grew less than 100 CFU/cath, and 2/32 (controls), 19/68 (teico) and 10/72 (rifa) cath grew less than 1000 CFU/cath. For QPCR, 1/56 (control), 0/68 (teico) and 0/72 (rifa) yielded less than 1000 copies DNA. All samples containing DNA also contained mRNA. QPCR had a significantly higher yield than QCC in the teico (p<0.0001; chi-square) and rifa (p=0.001) group, but not in the controls. CONCLUSIONS: Teicoplanin and rifampin cause respectively 28% and 14% false negative catheter cultures when using the 1000 CFU/cath limit, and 19% and 6% false negative catheters with the 100 CFU/cath limit. CFU at day 1 were very small and could easily be missed. For patients taking antibiotics, negative catheter culture does not exclude catheter infection. The 100 CFU/cath limit and repeated counting of the plate at day 2 decrease but do not eliminate the effect of antibiotics on the yield of QCC.
Publication Types:
Keywords:
- Animals
- Anti-Bacterial Agents
- Bacteria
- Catheterization
- Colony Count, Microbial
- Humans
- Laboratory Techniques and Procedures
- Polymerase Chain Reaction
- Rats
- Rifampin
- Teicoplanin
- diagnosis
- organization & administration
Other ID:
UI: 102267455
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