Citation Details

Journal Article

Administration, Intranasal; Animals; Bioware; Disease Models, Animal; Female; Humans; Immunohistochemistry; Intracellular Fluid; Lymphoid Tissue; Mice; Mice, Inbred BALB C; Nasal Mucosa; Nasopharynx; Palatine Tonsil; pXen-5; Streptococcal Infections; Streptococcus pyogenes

Human tonsils are suspected to be an antibiotic-impervious human reservoir for group A streptococcus. An intranasal infection model in mice and a bioluminescent-tagged strain were used to investigate this possibility. Viable streptococci were predominantly found both intra- and extracellularly in nasal-associated lymphoid tissue (NALT), a human tonsil homologue. Ulex europaeus-1, a membranous (M) cell-specific lectin, identified cells harboring streptococci at the epithelial surface of NALT and blocked bacterial colonization of this tissue. These results suggest that M cells in NALT transport this Gram-positive pathogen across the epithelial layers in a manner similar to those in Peyer's patches, which permit enteric pathogens to invade deeper tissues from the gastrointestinal tract.

Journal Article

Amino Acid Transport Systems, Neutral; Animals; Bacterial Proteins; Bioware; Blotting, Northern; Disease Models, Animal; Gene Expression Regulation, Bacterial; Humans; Lac Operon; Mice; Osmolar Concentration; Proline; pXen-5; Recombinant Fusion Proteins; Staphylococcal Infections; Staphylococcus aureus; Symporters; Transcriptional Activation

Staphylococcus aureus can grow virtually anywhere in the human body but needs to import proline through low- and high-affinity proline transporters to survive. This study examined the regulation of the S. aureus putP gene, which encodes a high-affinity proline permease. putP::lacZ and putP::lux transcriptional fusions were constructed and integrated into the genomes of several S. aureus strains. Enzyme activity was measured after growth in media with various osmolyte concentrations. As osmolarity rose, putP expression increased, with a plateau at 2 M for NaCl in strain LL3-1. Proline concentrations as low as 17.4 muM activated expression of the putP gene. The putP::lux fusion was also integrated into the genomes of S. aureus strains that were either SigB inactive (LL3-1, 8325-4, and SH1003) or SigB active (Newman and SH1000). SigB inactive strains showed increased putP gene expression as NaCl concentrations rose, whereas SigB active strains displayed a dramatic decrease in putP expression, suggesting that the alternative sigma factor B plays a negative role in putP regulation. Mice inoculated with S. aureus strains containing the putP::lux fusion exhibited up to a 715-fold increase in putP expression, although levels in the various murine organs differed. Moreover, urine from human patients infected with S. aureus showed elevated putP levels by use of a PCR procedure, whereas blood and some abscess material had no significant increase. Thus, putP is transcriptionally activated by a low-proline and high osmotic environment both in growth media and in murine or human clinical specimens.

Journal Article

Animals; Biofilms; Bioware; Colony-Forming Units Assay; Disease Susceptibility; Female; Luminescence; Mice; Mice, SCID; pXen-5; Staphylococcal Infections; Staphylococcus epidermidis; T-Lymphocytes; T-Lymphocytes, Cytotoxic

Staphylococcus epidermidis is the leading cause of hospital-acquired device-related infections, but there is a lack of suitable methods to investigate the pathogenesis of S. epidermidis infection. We created a bioluminescent strain of S. epidermidis and developed a subcutaneous catheter-related murine infection model for real-time monitoring of biofilm-associated infection. Additionally, we compared severely immunocompromised and immunocompetent mice, demonstrating the substantial effect of animal immune status on susceptibility to experimentally induced S. epidermidis disease. This study presents a novel approach for investigating the in vivo details of the pathogenesis of S. epidermidis infection.

Journal Article

Animals; Anti-Bacterial Agents; Bioware; Connective Tissue; Diffusion; Drug Implants; Female; Mice; Mice, Inbred BALB C; Nitric Oxide; Polyvinyls; Prostheses and Implants; pXen-5; Staphylococcal Infections; Xen29

Infection of surgical meshes used in abdominal wall reconstructions often leads to removal of the implant and increases patient morbidity due to repetitive operations and hospital administrations. Treatment with antibiotics is ineffective due to the biofilm mode of growth of the infecting bacteria and bears the risk of inducing antibiotic resistance. Hence there is a need for alternative methods to prevent and treat mesh infection. Nitric oxide (NO)-releasing coatings have been demonstrated to possess bactericidal properties in vitro. It is the aim of this study to assess possible benefits of a low concentration NO-releasing carbon-based coating on monofilament polypropylene meshes with respect to infection control in vitro and in vivo. When applied on surgical meshes, NO-releasing coatings showed significant bactericidal effect on in vitro biofilms of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and CNS. However, using bioluminescent in vivo imaging, no beneficial effects of this NO-releasing coating on subcutaneously implanted surgical meshes in mice could be observed.

Journal Article

Abdominal Wall; Animals; Bioware; Female; Luminescent Measurements; Mice; Mice, Inbred BALB C; Polypropylenes; Polytetrafluoroethylene; pXen-5; Staphylococcal Infections; Staphylococcus aureus; Surgical Mesh; Xen29

OBJECTIVE To study the influence of morphology of surgical meshes on the course of bacterial infection under the influence of the host immune system in an in vivo chronic bacterial infection model. BACKGROUND The use of prosthetic meshes has increased dramatically the last decades in abdominal wall reconstructive surgery. Whereas infection is becoming a more frequent complication, attention is increasingly drawn to the influence of the surgeon's mesh choice on the course of this complication. METHODS Samples of 6 often applied surgical meshes were contaminated with a bioluminescent strain of Staphylococcus aureus and implanted subcutaneously in an immunocompetent BALB/c mouse. The intensity and the spreading of bioluminescence (ie, p/s/cm/sr) were analyzed non-invasively in vivo during a 10-day follow-up period. RESULTS Over the course of infection, multifilament polypropylene and hydrophobic materials showed a significantly higher persistence of bacteria as well as spreading of infection compared to all other meshes. In contrast, infection resolved in almost all animals with a low-weight polyester mesh. CONCLUSION The results of this study are in accordance with circumstantial evidence from limited clinical reports on infection involving surgical meshes and suggest that multifilament and hydrophobic meshes significantly increase bacterial persistence or spreading in the infected area in contrast to monofilament polypropylene and lightweight meshes. Therefore, the surgeon should consider this outcome when choosing a mesh graft for limiting infection in abdominal wall repair.