Virulence Attributes of Low-Virulence Organisms

The vast majority of infections involving female pelvic structures arise from organisms that are members of the normal flora. In addition, exogenous organisms that invade through the lower genital tract must interact with organisms that are part of the host's flora. In contrast to the concept that the normal flora is entirely innocuous, recent research has begun to identify what appear to be virulence attributes among these ordinarily low-virulence organisms. Most of our understanding of virulence has been derived from highly virulent organisms, of which Neisseria gonorrhoeae provides an example of relevance to the female genital tract. A review of the virulence factors of the gonococcus is presented to serve as an example of the variety of virulence properties associated with pathogenic bacteria. Molecular biology has begun to clarify one of the important paradigms of pathogenic bacteriology—that bacteria change their expression of virulence properties in response to their location within a host or to the stage of infection. Thus, infection involves not only the possession of virulence factors, but also the carefully controlled use of those factors. Virulence is often controlled by the coordinate expression of many virulence-associated genes in response to one environmental signal. With regard to low- virulence organisms present in the female lower genital tract, we are beginning to identify some of their virulence attributes. Examples from the work of our laboratory include the hemolysin of Gardnerella vaginalis and an immunosuppressive mycotoxin produced by Candida albicans. Demonstrating the coordinate expression (or other control mechanisms) of virulence factors in these sometimes innocuous and sometimes inimical organisms represents the next frontier in the study of normal vaginal microbiology

Antifungal Effect of Hydrogen Peroxide on Catalase-Producing Strains of Candida spp.

Objective: Clinical isolates of Candida were tested for the presence of catalase and susceptibility to hydrogen peroxide

Progesterone Interactions with the Cervix: Translational Implications for Term and Preterm Birth

The uterine cervix plays a vital role in maintaining pregnancy and an equally important role in allowing parturition to occur. Progesterone, either endogenously produced or supplied exogenously, supports the function of the cervix in sustaining intrauterine pregnancy, and the withdrawal of progesterone, either through natural processes or pharmacologic intervention, leads to delivery which underscores the importance of the progesterone's biological activities manifest in normal gestation and pregnancy that ends prematurely. Research crossing many scientific disciplines has demonstrated that progesterone is a pleotropic compound that affects the cervix through cytoplasmic and membrane receptors with profound effects on cellular and molecular functions that influence inflammatory cascades and extracellular matrix, both of which have consequences for parturition. Beyond the local cell and molecular biology of progesterone, it has systemic effects of relevance to pregnancy as well. This paper examines the biology of the cervix from its gross to cellular structure and biological activities of its cell and molecular processes that may be affected by progesterone. The implications of these processes for preterm birth are explored, and direction of current research is in relation to translational medicine implications for diagnostic, prognostic, and therapeutic approaches to threatened preterm birth

Mycoplasma, Ureaplasma, and Adverse Pregnancy Outcomes: A Fresh Look

Recent work on the Molicutes that associate with genital tract tissues focuses on four species that may be of interest in potential maternal, fetal, and neonatal infection and in contributing to adverse pregnancy outcomes. Mycoplasma hominis and Ureaplasma urealyticum have historically been the subject of attention, but Mycoplasma genitalis which causes male urethritis in addition to colonizing the female genital tract and the division of Ureaplasma into two species, urealyticum and parvum, has also added new taxonomic clarity. The role of these genital tract inhabitants in infection during pregnancy and their ability to invade and infect placental and fetal tissue is discussed. In particular, the role of some of these organisms in prematurity may be mechanistically related to their ability to induce inflammatory cytokines, thereby triggering pathways leading to preterm labor. A review of this intensifying exploration of the mycoplasmas in relation to pregnancy yields several questions which will be important to examine in future research

Development of a High Performance Liquid Chromatographic Assay Measuring Mezlocillin in Serum or Tissue

Objective: This study evaluated the blood and uterine tissue concentration of mezlocillin, a broadspectrum penicillin

Surface modifying substances that reduce apparent yeast cell hydrophobicity.

OBJECTIVE: To determine whether several topical compounds and other chemical entities are able to diminish the surface hydrophobicity of yeast cells. METHOD: Hydrophobicity of yeast cells was determined by binding styrene microspheres to the surface of untreated yeast or yeast pre-incubated with various substances with potential for cell surface modification. The degree of microsphere adherence to yeast cells was measured by flow cytometry. RESULTS: A significant reduction in cell surface hydrophobicity was observed when yeast was incubated in protein-containing media. Other compounds that effectively reduced microsphere binding were various formulations of K-Y and heparin. Divalent cations (Ca+ + , Mg+ + , Zn+ + , Cu + + ) were also potent inhibitors of microsphere adherence. It was possible to remove substances contributing to microsphere binding by chemical extraction of the yeast. Yeast having reduced microsphere binding activity also showed diminished binding of concanavalin A. CONCLUSIONS: Several commercially available compounds were able to block binding of styrene microspheres to yeast. Some of the binding activity appeared to be attributable to mannose-containing surface components. These findings have implications for formulating therapeutic products that might block yeast binding to tissues

Tetracycline Effects on Candida Albicans Virulence Factors

Object. To determine if tetracycline, previously reported to increase the probability of developing symptomatic vaginal yeast infections, has a direct effect on Candida albicans growth or induction of virulent phenotypes. Method. In vitro, clinical isolates of yeast were cultivated with sublethal concentrations of tetracycline and yeast cell counts, hyphal formation, drug efflux pump activity, biofilm production, and hemolysin production were determined by previously reported methods. Results. Tetracycline concentrations above 150 μg/mL inhibited Candida albicans, but at submicrogram/mL, a modest growth increase during the early hours of the growth curve was observed. Tetracycline did not inhibit hyphal formation at sublethal concentrations. Hypha formation appeared augmented by exposure to tetracycline in the presence of chemically defined medium and especially in the presence of human serum. Efflux pump CDR1 was upregulated and a nonsignificant trend toward increased biofilm formation was noted. Conclusion. Tetracycline appears to have a small growth enhancing effect and may influence virulence through augmentation of hypha formation, and a modest effect on drug efflux and biofilm formation, although tetracycline did not affect hemolysin. It is not clear if the magnitude of the effect is sufficient to attribute vaginitis following tetracycline treatment to direct action of tetracycline on yeast

Navigating the Third Frontier of Antimicrobial Therapy to Support Women’s Health

This paper explores one of the underappreciated reasons for lack of efficacy in certain cases of antimicrobial therapy, namely the occurrence of a non-genetic resistance to antimicrobial drugs due to a metabolic quiescence of microorganisms. This review has centered on those microorganisms of particular importance in obstetrics and gynecology and accordingly has reviewed the nature and extent of the persister phenotype in relation to infectious agents affecting women’s health. We show how the quiescent persister microbial phenotype represents the next significant issue that could compromise successful antibiotic therapy. A brief history of antimicrobial therapy is provided as context for the problem posed by the persister phenotype. This review has been focused on the current literature having relevance for physicians concerned with women’s health. The study of this phenotype has led to increasing understanding of the molecular mechanisms for this state which also provides ideas for rational development of drug candidates to interdict these organisms in human disease and explores the possibility of developing specifically targeted molecules to address persisters, research on screening botanicals, existing drugs and chemicals to discover novel approaches to the clinical consequence of microbial persisters. Of interest in this review, is the return to naturally occurring botanical substances, first to be used as anti-infectives, now being considered as possible agents to address persister microorganisms. Overall this paper aims to provide information tailored especially to the obstetrics and gynecology specialists

Adherence and Blocking of Candida Albicans to Cultured Vaginal Epithelial Cells: Treatments to Decrease Adherence

Background. Pathogenesis of mucosal microorganisms depends on adherence to the tissues they colonize and infect. For Candida albicans, cell surface hydrophobicity may play a significant role in tissue binding ability. Methods. A continuous cell line of vaginal epithelial cells (VEC) was grown in keratinocyte serum-free medium (KSFM) with supplements and harvested by trypsinization. VEC were combined with yeast cells to evaluate adherence and inhibition of adherence. In this experimental setup, yeast stained with fluorescein isothiocyanate were allowed to attach to VEC and the resulting fluorescent VEC were detected by flow cytometry. Results. VEC were cultured and examined daily after plating and showed morphology similar to basal epithelial cells. Culture media supplemented with estradiol showed increased VEC proliferation initially (first 24 h) but cell morphology was not altered. Fluorescinated Candida cells bound effectively to the cultured VEC. Using fresh cells exposed to various preparations of K-Y, we showed that all formulations of the product reduced Candida binding to VEC by 25% to 50%. While VEC were generally harvested for use in experiments when they were near confluent growth, we allowed some cultures to grow beyond that point and discovered that cells allowed to become overgrown or stressed appeared to bind yeast cells more effectively. Conclusion. Flow cytometry is a useful method for evaluating binding of stained yeast cells to cultured VEC and has demonstrated that commercially available products have the ability to interfere with the process of yeast adherence to epithelial cells

Candidiasis During Pregnancy May Result From Isogenic Commensal Strains

Objective: Our laboratory previously demonstrated that asymptomatic vaginal colonization during pregnancy is a factor predisposing patients to subsequent symptomatic vulvovaginal candidiasis. It is unknown whether symptoms result from strain replacement or a change in host relationship to the original colonizing strain. This study was undertaken to determine whether Candida albicans isolates from asymptomatic women could be responsible for subsequent symptomatic vaginitis. Methods: We retained isolates of C. albicans from women followed longitudinally through pregnancy, and identified six pairs of cultures from women who were colonized without symptoms and who later became symptomatic (average time 14 weeks). We used a random amplification of polymorphic DNA (RAPD) analysis to determine whether isolates from our study patients were genetically similar or dissimilar. Results: Analysis of these pairs of yeast strains by RAPD revealed that five of the six women had symptoms apparently due to the same yeast strain that was found initially as a commensal strain. To increase the power of these observations, we also performed RAPD analysis on six randomly selected yeast strains from other women in this study who had not become symptomatic to determine whether any of these unrelated strains matched strains from those women who became symptomatic. Conclusion: Symptomatic yeast vaginitis is usually due to strains of C. albicans already carried in the lower genital tract, underscoring the need to understand regulation of growth and virulence of the organism in vivo