Biofilm formation by Staphylococcus epidermidis depends on functional RsbU, an activator of the sigB operon: differential activation mechanisms due to ethanol and salt stress.

Staphylococcus epidermidis is a common pathogen in medical device-associated infections. Its major pathogenetic factor is the ability to form adherent biofilms. The polysaccharide intercellular adhesin (PIA), which is synthesized by the products of the icaADBC gene cluster, is essential for biofilm accumulation. In the present study, we characterized the gene locus inactivated by Tn917 insertions of two isogenic, icaADBC-independent, biofilm-negative mutants, M15 and M19, of the biofilm-producing bacterium S. epidermidis 1457. The insertion site was the same in both of the mutants and was located in the first gene, rsbU, of an operon highly homologous to the sigB operons of Staphylococcus aureus and Bacillus subtilis. Supplementation of Trypticase soy broth with NaCl (TSB(NaCl)) or ethanol (TSB(EtOH)), both of which are known activators of sigB, led to increased biofilm formation and PIA synthesis by S. epidermidis 1457. Insertion of Tn917 into rsbU, a positive regulator of alternative sigma factor sigma(B), led to a biofilm-negative phenotype and almost undetectable PIA production. Interestingly, in TSB(EtOH), the mutants were enabled to form a biofilm again with phenotypes similar to those of the wild type. In TSB(NaCl), the mutants still displayed a biofilm-negative phenotype. No difference in primary attachment between the mutants and the wild type was observed. Similar phenotypic changes were observed after transfer of the Tn917 insertion of mutant M15 to the independent and biofilm-producing strain S. epidermidis 8400. In 11 clinical S. epidermidis strains, a restriction fragment length polymorphism of the sigB operon was detected which was independent of the presence of the icaADBC locus and a biofilm-positive phenotype. Obviously, different mechanisms are operative in the regulation of PIA expression in stationary phase and under stress induced by salt or ethanol.

Acute and long-term humoral immunity following active immunization of rabbits with inactivated spores of various Encephalitozoon species.

Microsporidia of the genus Encephalitozoon are increasingly being reported as a cause of severe, often disseminated infections, mainly in patients with acquired immunodeficiency syndrome (AIDS). Immunological identification of each of the three recognized species (E. cuniculi, E. hellem, and E. intestinalis) requires the availability of specific immune sera. All sera available thus far have been generated by direct inoculation of rabbits with virulent microsporidian spores. This study demonstrates for the first time that subcutaneous immunization with inactivated spores of E. cuniculi, E. helleri, or E. intestinalis is capable of generating highly active rabbit hyperimmune sera to the homologous antigens, with maximal titers being 1:5,120, 1:1,280, and 1:2,560, respectively, as determined by the indirect immunofluorescence technique (IIF). Broad cross-reactivity of the rabbit antisera with all heterologous Encephalitozoon antigens was determined by IIF and immunogold electron microscopy; however, only the E. hellem immune serum strongly cross-reacted with spores of Enterocytozoon bieneusi. During the 35-month follow-up period the antibody titers to the homologous antigens declined to 1:640, 1:160, and 1:320, respectively. The observed decay curves for antibody titers against E. cuniculi, E. hellem, and E. intestinalis were fitted using mathematical modeling, resulting in a predicted duration for specific immune responses of about 7 years on average. Knowledge of the magnitude and duration of specific immune responses is a prerequisite for further evaluation of the concept of using inactivated microsporidian spores in the quest for vaccines against microsporidian infections.

Characterization of the importance of polysaccharide intercellular adhesin/hemagglutinin of Staphylococcus epidermidis in the pathogenesis of biomaterial-based infection in a mouse foreign body infection model.

The production of biofilm is thought to be crucial in the pathogenesis of prosthetic-device infections caused by Staphylococcus epidermidis. An experimental animal model was used to assess the importance of biofilm production, which is mediated by polysaccharide intercellular adhesin/hemagglutinin (PIA/HA), in the pathogenesis of a biomaterial-based infection. Mice were inoculated along the length of a subcutaneously implanted intravenous catheter with either wild-type S. epidermidis 1457 or its isogenic PIA/HA-negative mutant. The wild-type strain was significantly more likely to cause a subcutaneous abscess than the mutant strain (P < 0.01) and was significantly less likely to be eradicated from the inoculation site by host defense (P < 0.05). In addition, the wild-type strain was found to adhere to the implanted catheters more abundantly than the PIA/HA-negative mutant (P < 0.05). The reliability of the adherence assay was assessed by scanning electron microscopy. To exclude contamination or spontaneous infection, bacterial strains recovered from the experimental animals were compared to inoculation strains by analysis of restriction fragment length polymorphism patterns by pulsed-field gel electrophoresis. In vitro binding of the wild-type strain and its isogenic mutant to a fibronectin-coated surface was similar. These results confirm the importance of biofilm production, mediated by PIA/HA, in the pathogenesis of S. epidermidis experimental foreign body infection.

From crisis to success. Turning around a family practice residency program.

On Match Day in 1991, Broadlawns Medical Center in Des Moines, Iowa, learned that no residents had matched for the family practice residency program. In the 1992 match, the medical center filled all its residency positions, and repeated the success in the 1993 and 1994 matches. Broadlawns affected this impressively rapid turnaround through a strong commitment to bring its program to a level competitive with leading family practice residency programs, substantive changes to the structure and curriculum of the program, and significant expenditures of time, resources and personal energy. The Broadlawns' case illustrates the need for family practice residency programs to position themselves as strong competitors in the residency market.

Sexuality and reproduction in spinal cord injured women.

Sexuality, reproduction, and childbearing are essential issues for the spinal cord injured women. The medical complications, including urinary tract infections, anemia, pressure sores, sepsis, and autonomic hyperreflexia are significant in each of these areas with both physical as well as emotional ramifications. Patient and family education is of primary importance in both anticipating as well as dealing with the potentially serious consequences. A consultant knowledgeable in the problems of the spinal cord injured can be of utmost benefit especially in the labor and delivery process.

A technique to study the passive supports of the uterus.

The present report concerns the position of the portio vaginalis of the uterine cervix when known amounts of downward force are applied to it under anesthesia. It is intended to provide a quantitative assessment of the passive supports of the uterus relatively independent of the active striated muscles in the pelvis. The measurements were made by connecting to the cervix a uterine insufflation cannula with a ruler attached to it and measuring the distance from the hymen to the ectocervix while varying amounts of downward traction were applied to a tenaculum with a spring scale. In 73 asymptomatic patients, the cervix lay above the hymen by the following distance with the amount of traction stated: 0 lb = 3.50 cm, 1 lb = 2.35 cm, 2 lb = 1.65 cm, 3 lb = 1.16 cm, and 4 lb = 0.81 cm. In 22 patients examined independently by two examiners, the mean difference between these measurements was 0.29 cm, and the correlation coefficient for their measurements at each level of traction ranged from 0.86-0.94, depending on the amount of force applied. This technique of measurement could be used to study the influence of such factors as age, race, parity, menopausal status, and obstetric history on the integrity of the passive support system within a population, and can provide a way to obtain objective data to study further the passive supports of the uterus.