Jessica L. Cutright

Effects of reproductive hormones on experimental vaginal candidiasis.

ABSTRACT Vulvovaginal candidiasis (VVC) is an opportunistic mucosal infection caused by Candida albicans that affects large numbers of otherwise healthy women of childbearing age. Acute episodes of VVC often occur during pregnancy and during the luteal phase of the menstrual cycle, when levels of progesterone and estrogen are elevated. Although estrogen-dependent experimental rodent models of C. albicans vaginal infection are used for many applications, the role of reproductive hormones and/or their limits in the acquisition of vaginal candidiasis remain unclear. This study examined the effects of estrogen and progesterone on several aspects of an experimental infection together with relative cell-mediated immune responses. Results showed that while decreasing estrogen concentrations eventually influenced infection-induced vaginal titers of C. albicansand rates of infection in inoculated animals, the experimental infection could not be achieved in mice treated with various concentrations of progesterone alone. Furthermore, progesterone had no effect on (i) the induction and persistence of the infection in the presence of estrogen, (ii) delayed-type hypersensitivity in primary-infected mice, or (iii) the partial protection from a secondary vaginal infection under pseudoestrus conditions. Other results with estrogen showed that a persistent infection could be established with a wide range of C. albicans inocula under supraphysiologic and near-physiologic (at estrus) concentrations of estrogen and that vaginal fungus titers or rates of infection were similar if pseudoestrus was initiated several days before or after inoculation. However, the pseudoestrus state had to be maintained for the infection to persist. Finally, estrogen was found to reduce the ability of vaginal epithelial cells to inhibit the growth of C. albicans. These results suggest that estrogen, but not progesterone, is an important factor in hormone-associated susceptibility to C. albicans vaginitis.

Vaginal-Associated Immunity in Women with Recurrent Vulvovaginal Candidiasis: Evidence for Vaginal Th1-Type Responses following Intravaginal Challenge with Candida Antigen

Studies from women with recurrent vulvovaginal candidiasis (RVVC) and from an animal model of experimental vaginitis suggest that deficiencies in immune function should be examined at the local rather than systemic level. Evidence of vaginal cell-mediated immunity (CMI) was evaluated for the first time in cervicovaginal lavage (CVL) fluid from RVVC patients. Results showed that although constitutive Th1- and Th2-type cytokine expression was detectable in CVL fluid from normal women, and differences in cytokines were observed in RVVC patients, limitations in experimental design of such de novo analyses urged caution in interpretation. Alternatively, attempts were made to establish conditions in control subjects whereby vaginal immunity could be detected after intravaginal challenge with Candida antigen. Preliminary results showed that Th1-type cytokines (interleukin-2 and -12, interferon-gamma) and histamine were increased 16-18 h after intravaginal introduction of Candida skin test antigen. Intravaginal antigenic challenge represents a novel approach for studying Candida-specific vaginal CMI.

Candida-Specific Systemic Cell-Mediated Immune Reactivities in Human Immunodeficiency Virus—Positive Persons with Mucosal Candidiasis

Oropharyngeal candidiasis (OPC), as opposed to vulvovaginal candidiasis (VVC), is a common opportunistic infection in human immunodeficiency virus (HIV)-positive persons that correlates with reduced CD4 T cell counts. Although cell-mediated immunity (CMI) by CD4 Th1-type cells is considered to be the predominant host defense against mucosal candidiasis, the immune factors associated with susceptibility to OPC in HIV-positive persons are not well understood. This study investigated Candida-specific systemic CMI in HIV-positive persons with OPC and/or VVC. Reductions in delayed skin test reactivity to Candida antigen were observed in HIV-positive persons with CD4 cell counts <200 cells/microL, irrespective of the presence of mucosal infection. Likewise, despite the correlate of OPC with reduced CD4 cell counts in HIV-positive persons, differences in Candida-specific peripheral blood mononuclear cell proliferation and Th1/Th2 cytokine production between HIV-positive and HIV-negative persons were not consistent in a manner to suggest that deficiencies in Candida-specific systemic CMI account solely for the susceptibility to OPC.

In vitro susceptibilities of Aspergillus species to voriconazole, itraconazole, and amphotericin B

We studied the in vitro activity of voriconazole (VCZ) itraconazole (ITZ) and amphotericin B (AMB) against 216 clinical isolates of Aspergillus spp. (142 Aspergillus fumigatus and 74 nonfumigatus Aspergillus spp. isolates) using a broth macrodilution method. The MICs (microgram/mL) (mean, range) for A. fumigatus were: VCZ 0.88, 0.25-4; ITZ 0.54, 0.25-4; AMB 2.16, 0.5-8. MIC90s were: VCZ 2, ITZ 1, AMB 4. MICs for nonfumigatus Aspergillus spp. were: VCZ 1.57, 0.25-4; ITZ 1.74, 0.25-4; AMB 2.88, 0.5-8. MIC90s for this group were: VCZ 4, ITZ 4, AMB 4. We also studied the susceptibility to VCZ of 18 AMB-resistant (mean, MIC 6.0 micrograms/mL) and 28 ITZ-resistant (mean, MIC 13.28 micrograms/mL) A. fumigatus isolates selected in the laboratory. The mean MICs of VCZ were 0.59 microgram/mL for AMB-resistant and 1.32 micrograms/mL for ITZ-resistant isolates. Our study showed that VCZ and ITZ had comparable in vitro activity against the isolates studied, except against A. fumigatus, where the MIC of ITZ was lower. The azoles had better in vitro activity than AMB against A. fumigatus and non-fumigatus spp. The non-fumigatus Aspergillus spp. were less susceptible to all three antifungals evaluated. When tested against ITZ- or AMB-resistant A. fumigatus strains, VCZ retained good activity, showing only a modest rise in the MIC against ITZ-resistant strains.

Interleukin-1 receptor antagonist (IL-1ra) production by human amnion, chorion, and decidua

PROBLEM: This study was conducted to determine whether (1) conditioned media from unstimulated primary cultures of human amnion, chorion, or decidua contain detectable concentrations of IL‐lra in vitro, and (2) bacterial endotoxin (LPS), tumor necrosis factor‐alpha (TNF‐α), or IL‐1‐beta (IL‐1β) stimulate amnion, chorion, or decidua to produce increased amounts of IL‐1ra.

Aspergillus: rising frequency of clinical isolation and continued susceptibility to antifungal agents, 1994–1999

We investigated the frequency of clinical isolation and the in vitro susceptibility to antifungal agents of Aspergillus species obtained from patients at the Detroit Medical Center from January 1994 to December 1999. During this period, 593 clinical isolates of Aspergillus species [406 A. fumigatus, 68%; 82 A. niger, 14%; 42 A. flavus, 7%; 63 Aspergillus spp., 11%] were recovered from hospitalized patients. From January 1996 to December 1999, approximately 2.5-4.5 fold yearly increase of the number of aspergillus isolates occurred compared to that of 1994. Conidial suspensions from clinical isolates were prepared and their in vitro susceptibility to amphotericin B and three azoles were determined. All four agents examined were extremely active. The minimum inhibitory concentrations (MIC(90)) (microg/mL) of amphotericin B, itraconazole, voriconazole and posaconazole for A. fumigatus (n = 406) were 0.5, 1.0, 0.5 and 0.25. Similar values were noted for non-A. fumigatus isolates. A year-to-year comparison of the MIC(90) of the four agents for A. fumigatus and non-A. fumigatus isolates over the 6-year study period showed no significant differences. Our study showed a steady increase in the frequency of clinical isolation of Aspergillus species; and the organism has remained susceptible to amphotericin B/triazoles without any change in susceptibility levels during the 6-year study period.

Clostridium Difficile Colonization in Hematopoietic Stem Cell Transplant Recipients: A Prospective Study of the Epidemiology and Outcomes Involving Toxigenic and Nontoxigenic Strains

Clostridium difficile is a leading cause of infectious diarrhea in hematopoietic stem cell transplant (HSCT) recipients. Asymptomatic colonization of the gastrointestinal tract occurs before development of C. difficile infection (CDI). This prospective study examines the rates, risk factors, and outcomes of colonization with toxigenic and nontoxigenic strains of C. difficile in HSCT patients. This 18-month study was conducted in the HSCT unit at the Karmanos Cancer Center and Wayne State University in Detroit. Stool samples from the patients who consented for the study were taken at admission and weekly until discharge. Anaerobic culture for C. difficile and identification of toxigenic strains by PCR were performed on the stool samples. Demographic information and clinical and laboratory data were collected. Of the 150 patients included in the study, 29% were colonized with C. difficile at admission; 12% with a toxigenic strain and 17% with a nontoxigenic strain. Over a 90-day follow-up, 12 of 44 (26%) patients colonized with any C. difficile strain at admission developed CDI compared with 13 of 106 (12%) of patients not colonized (odds ratio [OR], 2.70; 95% confidence interval [95% CI], 1.11 to 6.48; P = .025). Eleven of 18 (61%) patients colonized with the toxigenic strain and 1 of 26 (4%) of those colonized with nontoxigenic strain developed CDI (OR, 39.30; 95% CI, 4.30 to 359.0; P < .001) at a median of 12 days. On univariate and multivariate analyses, none of the traditional factors associated with high risk for C. difficile colonization or CDI were found to be significant. Recurrent CDI occurred in 28% of cases. Asymptomatic colonization with C. difficile at admission was high in our HSCT population. Colonization with toxigenic C. difficile was predictive of CDI, whereas colonization with a nontoxigenic C. difficile appeared protective. These findings may have implications for infection control strategies and for novel approaches for the prevention and preemptive treatment of CDI in the HSCT patient population.

In vitro–in vivo correlation of voriconazole resistance due to G448S mutation (cyp51A gene) in Aspergillus fumigatus☆☆☆★

Invasive pulmonary aspergillosis continues to be associated with a high mortality despite timely and appropriate therapy. Although host immunity plays a major role in poor clinical response, antifungal drug resistance cannot be ignored. Our studies were aimed 1) to study the mechanism of drug resistance in voriconazole strains of Aspergillus fumigatus, 2) to establish a causal relationship between cyp51A mutation and voriconazole resistance (VRC-R), and 3) to determine whether VRC-R due to cyp51A mutation correlated with in vivo resistance. A point mutation (G448S) involving cyp51A gene in VRC-R isolate was associated with resistance to VRC but not to posaconazole (POS); POS had superior activity to VRC in reducing lung fungal burden and mortality in mice infected with a VRC-R mutant of A. fumigatus. Our study demonstrated that azole resistance is based on specific site of cyp51A mutation and that in vitro VRC-R correlates with in vivo resistance.

Efficacy of anidulafungin, caspofungin and fluconazole in the early phase of infection in a neutropenic murine invasive candidiasis model

In this study, we investigated the in vivo efficacy of anidulafungin during the early phase of disseminated candidiasis in a neutropenic murine model and compared the results with those obtained for fluconazole. Antifungal efficacy was evaluated by reduction of fungal burden in the tissues of infected animals at periodic intervals during the first day of treatment. The fungal burden in tissues of drug-treated mice was reduced compared with controls in a time-dependent manner. At 24h after drug treatment, a >2 log(10) reduction of fungal burden in the kidney was obtained in the anidulafungin- and caspofungin-treated mice compared with a ca. 1.2 log(10) reduction in fluconazole-treated mice (P<0.003). There was no significant difference in the splenic fungal burden at 24h. Thus, echinocandins have excellent antifungal activity in the early phase of disseminated Candida albicans infection and may contribute to an improved outcome in critically ill immunocompromised/neutropenic patients.

In Vivo Resistance of a Laboratory-Selected Aspergillus fumigatus Isolate to Amphotericin B

ABSTRACT The fungal burdens (number of CFU per pair of lungs) in mice infected with Aspergillus fumigatus AB16.4 (for which the amphotericin B [AMB] MIC was elevated) and W73355 (drug-susceptible parent) were reduced by 21 and 81%, respectively, after 5 days of AMB treatment (2 mg/kg/day), indicating that AB16.4 also shows reduced susceptibility to AMB in a murine pulmonary aspergillosis model.