Arthritis is developed in Borrelia-primed and -infected mice deficient of interleukin-17.

Interleukin-17 (IL-17) has been shown to participate in the development of Lyme arthritis in experimental mice. For example, neutralization of IL-17 with antibodies inhibits induction of arthritis in Borrelia-primed and -infected C57BL/6 wild-type mice. We hypothesized that mice lacking IL-17 would fail to develop Borrelia-induced arthritis. IL-17-deficient and wild-type C57BL/6 mice were primed with heat-inactivated Borrelia and then infected with viable spirochetes 3 weeks later. No swelling or major histopathological changes of the hind paws were detected in IL-17-deficient or wild-type mice that were primed with Borrelia or infected with viable spirochetes. By contrast, IL-17-deficient and wild-type mice that were primed and subsequently infected with heterologous Borrelia developed severe swelling and histopathological changes of the hind paws. In addition, Borrelia-primed and -infected IL-17-deficient mice exhibited elevated gamma-interferon (IFN-γ) levels in sera and increased frequencies of IFN-γ-expressing lymphocytes in popliteal lymph nodes compared to Borrelia-primed and -infected wild-type mice. These results demonstrate that IL-17 is not required for development of severe pathology in response to infection with Borrelia burgdorferi, but may contribute to disease through an interaction with IFN-γ.

Significant differences between the Borrelia-infection and Borrelia-vaccination and -infection models of Lyme arthritis in C3H/HeN mice.

The immunological events leading to the development of Lyme arthritis in humans are partially understood. Much of this information has been gained by studying the course of infection of naïve or vaccinated mice with Borrelia burgdorferi. However, the Borrelia-vaccination and -infection model has not been described using the organismal parameters commonly used in the widely accepted Borrelia-infection model. This is the first comparison between the Borrelia-infection and the Borrelia-vaccination and -infection models of arthritis. Borrelia-vaccinated and -infected C3H/HeN mice develop acute inflammation comparable to that of nonvaccinated, Borrelia-infected C3H/HeN mice. The duration and severity of arthritis in Borrelia-vaccinated and -infected mice was slightly increased compared with Borrelia-infected mice. Significantly, Borrelia-vaccinated and -infected C3H/HeN mice produce interleukin-17 (IL-17), while Borrelia-infected mice that had not been previously vaccinated do not. Neutralization of IL-17 in Borrelia-vaccinated and -infected C3H/HeN mice decreased the severity of arthritis, although not to the degree we observed previously in C57BL/6 mice. Collectively, these findings show that the Borrelia-vaccination and -infection model of Lyme arthritis incorporates elements of adaptive immunity that likely have relevance to human disease, but may not be observed in Borrelia-infected C3H/HeN mice.

Human Lyme disease vaccines: past and future concerns.

The development of a vaccine for Lyme disease was intensely pursued in the 1990s. However, citing a lack of demand, the first human Lyme disease vaccine was withdrawn from the market less than 5 years after its approval. The public's concerns about the vaccine's safety also likely contributed to the withdrawal of the vaccine. Nearly a decade later, no vaccine for human Lyme disease exists. The expansion of Lyme disease's endemic range, as well as the difficulty of diagnosing infection and the disease's steady increase in incidence in the face of proven preventative measures, make the pursuit of a Lyme disease vaccine a worthwhile endeavor. Many believe that the negative public perception of the Lyme disease vaccine will have tarnished any future endeavors towards its development. Importantly, many of the drawbacks of the Lyme disease vaccine were apparent or foreseeable prior to its approval. These pitfalls must be confronted before the construction of a new, effective and safe human Lyme disease vaccine.

Comparison of three commercial test systems for biotyping Haemophilus influenzae and Haemophilus parainfluenzae.

The biotypes of Haemophilus influenzae and Haemophilus parainfluenzae isolates were determined with three commercially available biochemical test kits: the IDS RapID NH system, the Neisseria-Haemophilus identification test (NHI card), and the API NH strip. The API NH strip performed best, correctly classifying the biotypes of 371 of 380 (97.6%) different challenge strains.

Interleukin-6 promotes anti-OspA borreliacidal antibody production in vitro.

Determination of the immunological mediators responsible for promoting the production of borreliacidal antibody may facilitate the development of an improved borreliosis vaccine for human and veterinary use. Previously, we developed an in vitro assay to determine if borreliacidal antibody production could be augmented by treatment with different cytokines. In this study, in vitro treatment of lymph node cells producing borreliacidal antibody with recombinant interleukin-6 (rIL-6) resulted in a fourfold enhancement of anti-OspA borreliacidal antibody. Moreover, rIL-6 enhanced Western immunoblot titers and increased the number of B lymphocytes. In contrast, treatment of anti-OspA borreliacidal antibody-producing cells with anti-IL-6 resulted in a fourfold reduction in borreliacidal activity. Treatment with anti-IL-6 also inhibited enhanced borreliacidal antibody production induced by anti-gamma interferon. These data suggest that IL-6 plays a significant role in the production of anti-OspA borreliacidal antibodies.

In vitro exposure of bacteria to antimicrobial impregnated-central venous catheters does not directly lead to the emergence of antimicrobial resistance.

OBJECTIVE: Use of central venous catheters (CVCs) impregnated with minocycline and rifampin reduces the density of bacterial growth on catheters and decreases the incidence of catheter-related bloodstream infections. Questions have been raised over the possibility that the use of these catheters will lead to the emergence of antibiotic-resistant organisms. In this study, we sought to determine if in vitro exposure of four test organisms to catheter segments impregnated with minocycline and rifampin would lead to the development of antibiotic resistance. METHODS: Catheter segments (1.0 cm) were placed on the surface of agar plates previously inoculated with bacterial suspensions, such that a subconfluent lawn of colony growth would be apparent after 24 h incubation at 35 degrees C in air. Test organisms included American Type Culture Collection strains of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Zones of inhibition of colony growth surrounding catheters were measured at 24-h intervals up to 7 days (two catheter segments per test). Colonies on agar surfaces located at varying distances from catheter segments were examined for minocycline and rifampin resistance following various periods of exposure (six catheter segments per test). In addition, selected colonies were subsequently exposed to minocycline and rifampin in broth and examined for selection of minocycline and rifampin resistance (> 28 colonies per selection test). RESULTS: Inhibitory zones of 14 to 47 mm were observed with S aureus, S epidermidis, E faecalis, and E coli. Growth of P aeruginosa was not inhibited by CVC segments. Testing of colonies of the first four organisms at various distances from CVC segments after varying periods of exposure revealed only a single instance of the emergence of resistance (eg, S aureus vs rifampin). Recovery of resistant clones was enhanced with minocycline and rifampin broth selection; however, a direct link between CVC exposure and the emergence of resistance was not established. CONCLUSIONS: Our in vitro data suggest that the exposure of Gram-positive cocci to either rifampin or minocycline can lead to the development of resistance. However, exposure of bacteria to these antibiotics in combination does not directly lead to resistance. Clinical investigations will be required to determine the true risk and implications of the development of resistance.

Neutralization of gamma interferon augments borreliacidal antibody production and severe destructive Lyme arthritis in C3H/HeJ mice.

Development of a high level of sustained borreliacidal antibody is paramount for maintaining protection against infection with Borrelia burgdorferi. We show that production of borreliacidal antibody can be enhanced by preventing the effects of gamma interferon (IFN-gamma). When lymph node cells capable of producing borreliacidal antibody were cultured with anti-murine IFN-gamma, an eightfold increase in borreliacidal antibody production was obtained. However, anti-IFN-gamma treatment of these cells also enhanced their ability to adaptively induce arthritis. When anti-IFN-gamma-treated lymph node cells producing borreliacidal antibody were infused into C3H/HeJ mice and the mice were then challenged with B. burgdorferi, the mice developed severe destructive Lyme arthritis. Additional studies are needed to delineate the immune response responsible for the induction of arthritis and production of borreliacidal antibody. These studies are needed to ensure an effective and safe vaccine against infection with B. burgdorferi.

Detection and treatment of bloodstream infection: laboratory reporting and antimicrobial management.

We analyzed antimicrobial use in 509 episodes of clinically significant bloodstream infection to assess the impact that microbiology laboratory reporting had on antimicrobial management. Most therapy interventions occurred at the time of phlebotomy and after notification of Gram stain results by telephone. Release of antimicrobial susceptibility data had the least impact on antimicrobial management.

Destructive arthritis in vaccinated interferon gamma-deficient mice challenged with Borrelia burgdorferi: modulation by tumor necrosis factor alpha.

We found that Borrelia burgdorferi-vaccinated gamma interferon-deficient (IFN-gamma(0)) mice challenged with B. burgdorferi developed prominent chronic destructive osteoarthropathy. When these mice were treated with anti-tumor necrosis factor alpha (TNF-alpha) antibody, the severity of the destructive osteoarthritis was enhanced and affected the mobility of the animals. In addition, extensive swelling of the hind paws occurred. In contrast, treatment of B. burgdorferi-vaccinated, challenged IFN-gamma(0) mice with recombinant TNF-alpha (rTNF-alpha) inhibited the development of arthritis, including swelling of the hind paws. Moreover, treatment of vaccinated, challenged IFN-gamma(0) mice with anti-TNF-alpha inhibited fourfold the production of an antibody that kills B. burgdorferi, while treatment of vaccinated, challenged IFN-gamma(0) mice with rTNF-alpha slightly elevated the level of the borreliacidal antibody. These results suggest that the level of TNF-alpha directly or indirectly regulates the production of borreliacidal antibody and the development of vaccine-induced destructive Lyme osteoarthritis. Studies are in progress to determine the mechanism by which TNF-alpha-dependent cytokines generate the destructive arthritis.

Presumptive identification of Candida kefyr on levine formulation of eosin methylene blue agar.

Three hundred thirty-one yeast and yeast-like isolates were cultivated on eosin methylene blue agar. While the sensitivity rate for Candida kefyr isolates producing a metallic green sheen was 81.8%, the high positive predictive value (100%) for yeast isolates with this phenotype belonging to C. kefyr suggests that these isolates can be presumptively identified as C. kefyr.

Modification of dienes mutual inhibition test for epidemiological characterization of Pseudomonas aeruginosa isolates.

Pseudomonas aeruginosa is an important cause of community-associated and nosocomial infections related to exposure to aqueous environments. Such infections often occur in the setting of a common-source outbreak, in which case epidemiological characterization of isolates may be necessary. In this preliminary study, a modification of the Dienes mutual inhibition test, ordinarily used to assess the relatedness of swarming Proteus mirabilis strains, was used to study 15 P. aeruginosa isolates, with the results compared to those obtained by ribotype analysis. Complete concordance was noted between the results of the Dienes test and those of ribotyping. These observations suggest that further studies are warranted to assess the utility of the modified Dienes test as a simple, inexpensive, and reliable means for epidemiological typing of P. aeruginosa.

Gamma interferon inhibits production of Anti-OspA borreliacidal antibody in vitro.

The ability of a Lyme borreliosis vaccine to induce and maintain sustained levels of borreliacidal antibody is necessary for prolonged protection against infection with Borrelia burgdorferi. Vaccination against infection with B. burgdorferi could be improved by determining the mechanism(s) that influences the production of protective borreliacidal antibody. Borreliacidal antibody was inhibited in cultures of lymph node cells obtained from C3H/HeJ mice vaccinated with formalin-inactivated B. burgdorferi and cultured with macrophages and B. burgdorferi and treated with recombinant gamma interferon (rIFN-gamma). The suppression of production of outer surface protein A (OspA) borreliacidal antibody by rIFN-gamma was not affected by the time of treatment. In addition, treatment with rIFN-gamma inhibited the production of other anti-B. burgdorferi antibodies. By contrast, treatment of cultures of immune lymph node cells with anti-IFN-gamma marginally increased the production of borreliacidal antibody and enhanced the production of other antibodies directed against B. burgdorferi. These results show that IFN-gamma does not play a major role in the production of anti-OspA borreliacidal antibody. Additional studies are needed to determine which cytokine(s) will enhance production of borreliacidal antibody.