Foreign body infection: a new rat model for prophylaxis and treatment

Wijngaerden, Eric Van; Peetermans, Willy; Vandersmissen, Jo; Lierde, S. Van; Bobbaers, Herman; Eldere, Johan Van

doi:10.1093/jac/44.5.669

Cited by 49 publications

(49 citation statements)

References 17 publications

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“…For all studies a previously described clinical Stapylococcal epidermidis strain (called 10b) was used (32). This strain was isolated from a patient with a proven catheter-related bloodstream infection.…”

Section: Methodsmentioning

confidence: 99%

Quantification of Expression of Staphylococcus epidermidis Housekeeping Genes with Taqman Quantitative PCR during In Vitro Growth and under Different Conditions

et al. 2001

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The aims of the present study were (i) to develop and test a sensitive and reproducible method for the study of gene expression in staphylococci and (ii) to study the expression of five housekeeping genes which are involved in nucleic acid metabolism (gmk, guanylate kinase; the dihydrofolate reductase [DHFR] gene), glucose metabolism (tpi, triosephosphate isomerase), and protein metabolism (the 16S rRNA gene; hsp-60, heat-shock protein 60) during in vitro exponential and stationary growth. A modified method for instant mRNA isolation was combined with gene quantification via Taqman real-time quantitative PCR. The detection limit of our method was 10 copies of RNA. The average intersample variability was 16%. A 10-fold increase in the expression of the hsp-60 gene was induced by exposure to a 10°C heat shock (37 to 47°C) for 10 min. During in vitro growth, the expression of all five housekeeping genes showed rapid up-regulation after inoculation of the bacteria in brain heart infusion medum and started to decline during the mid-exponential-growth phase. Maximal gene expression was 110-to 300-fold higher than gene expression during stationary phase. This indicates that housekeeping metabolism is a very dynamic process that is extremely capable of adapting to different growth conditions. Expression of the 16S rRNA gene decreases significantly earlier than that of other housekeeping genes. This confirms earlier findings for Escherichia coli that a decline in bacterial ribosomal content (measured by 16S rRNA gene expression) precedes the decline in protein synthesis (measured by mRNA expression).In recent years, coagulase-negative staphylococci (CNS) have emerged as major pathogens that are mainly associated with indwelling or implanted foreign body infections (22,29,30,33). Their impact on public health is enormous (24, 31). It remains enigmatic why these normally innocent skin saprophytes become virulent in association with indwelling foreign bodies (17). CNS infections seem to be the result of a complex interaction between bacterium-related factors, host-related factors, and foreign body-related-factors. Genes involved in cell accumulation (13,33,34) and in initial adhesion (12) are presumed virulence factors in initial foreign body colonization and biofilm formation. A state of bacterial dormancy and a suppressed housekeeping metabolism are hypothesized to contribute to the persistent nature of foreign body-related CNS infections (5,25,26).For study of the pathogenesis of infectious diseases, researchers have access to a rapidly growing amount of genetic information. However, the exact links between the information encoded in the genome and the final virulence and housekeeping behavior of bacteria remain unclear. Methods to unravel these links are mutagenesis and the study of gene expression. Mutagenesis is a valuable phenotypical assay (1). However, mutations in important genes may lead to only minor phenotypical changes or to lethal mutants. In these cases it is not possible to draw firm conclusions on the role...

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Section: Methodsmentioning

confidence: 99%

Quantification of Expression of Staphylococcus epidermidis Housekeeping Genes with Taqman Quantitative PCR during In Vitro Growth and under Different Conditions

et al. 2001

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“…A Fisher rat strain was inbred and has been maintained under germ-free conditions in the Rega Institute, University of Leuven, since 1965(Van Wijngaerden et al, 1999Vandecasteele et al, 2002). The first-generation descendants of these germ-free rats, born and reared under normal non-germ-free conditions were used.…”

Section: Methodsmentioning

confidence: 99%

The role of σ B in persistence of Staphylococcus epidermidis foreign body infection

et al. 2008

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Staphylococcal biofilm formation depends on the transcription factor s B . We further investigated the role of s B in biofilm formation and persistence in vitro and in vivo in a subcutaneous rat model. As expected, expression of all s B operon genes was transiently higher in the first 6 h of biofilm formation compared to planktonic bacteria, concurrent with a temporary upregulation of icaA and aap expression. However, we also observed a second upregulation of sigB expression in biofilm more than 2 days old without upregulation of icaA or aap. Biofilm formation by Staphylococcus epidermidis strains 8400 and 1457 was compared to that of isogenic mutants with inactivation of rsbU, of rsbUVW and of the entire s B operon. Both wild-type strains and the constitutively sigBexpressing rsbUVW mutant showed a strong biofilm-positive phenotype. The rsbUVW mutant biofilm was, however, thinner and more evenly spread than the wild-type biofilm. Inactivation of SigB in the rsbUVWsigB mutant or mutation of the positive regulator RsbU reduced both the number of sessile bacteria and polysaccharide intercellular adhesin (PIA) synthesis. These differences between the wild-types and their respective mutants appeared after 6 h in in vitro biofilms but only after 4 days in in vivo biofilms. Our results provide additional evidence for a role for s B in biofilm formation. They also suggest a role for s B in biofilm maturation and stability that is independent of PIA or accumulation-associated protein (Aap) and point to significant differences in the temporal development between in vitro and in vivo biofilms.

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“…For all experiments, a previously well-characterized biofilmproducing Staphylococcus epidermidis strain, strain 10b, which was isolated from a patient with a proven catheter-related bloodstream infection, was used (25,26,27). This strain has a 100% infection rate in the rat model used (27).…”

Section: Methodsmentioning

confidence: 99%

“…We used a previously described model in which first-generation descendants of inbred Fisher rats harbored under germfree conditions since 1965 were used (27). These rats, exposed to normal rat flora from birth, were labeled ex-germfree Fisher rats.…”

Section: Methodsmentioning

confidence: 99%

“…These rats, exposed to normal rat flora from birth, were labeled ex-germfree Fisher rats. In this model, which resembles the other subcutaneous models for FBI, catheter fragments were inoculated with a small amount of S. epidermidis 10b before implantation, which resulted in a 100% infection rate (27). The experimental conditions have been described in detail previously (25,26).…”

Section: Methodsmentioning

confidence: 99%

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Metabolic Activity of Staphylococcus epidermidis Is High during Initial and Low during Late Experimental Foreign-Body Infection

et al. 2004

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Foreign-body infection (FBI) is notoriously resistant to eradication by antibiotic treatment. It is hypothesized that reduced bacterial metabolic activity contributes to this resistance. We examined the metabolic activity of Staphylococcus epidermidis in 204 samples recovered during in vitro foreign-body colonization and in 424 samples recovered during in vivo FBI in a rat model. Metabolic activity was measured by determining the amount of 16S rRNA per genome by quantitative PCR. The initial foreign-body-associated growth proved to be a metabolically active process, both in vitro and in vivo. The initial 16S rRNA content was similar to that observed during in vitro exponential-growth phase. However, during late in vivo FBI, a 114-fold (P Ͻ Ͻ 0.0001) decrease in the 16S rRNA content was observed, indicating that there was markedly decreased metabolic activity. This decreased metabolic activity during late FBI can explain at least in part why such infections are so difficult to eradicate with conventional antibiotic treatment.

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Foreign body infection: a new rat model for prophylaxis and treatment

Cited by 49 publications

References 17 publications

Quantification of Expression of Staphylococcus epidermidis Housekeeping Genes with Taqman Quantitative PCR during In Vitro Growth and under Different Conditions

Quantification of Expression of Staphylococcus epidermidis Housekeeping Genes with Taqman Quantitative PCR during In Vitro Growth and under Different Conditions

The role of σ B in persistence of Staphylococcus epidermidis foreign body infection

Metabolic Activity of Staphylococcus epidermidis Is High during Initial and Low during Late Experimental Foreign-Body Infection

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