A longitudinal study on fluconazole resistance in Candida albicans vaginal isolates.

BACKGROUND: Recurrent vulvovaginal candidiasis (RVVC), despite its worldwide prevalence, has limited treatment options; and a long-term prophylactic regimen utilising fluconazole is the dominant choice. OBJECTIVES: An increase in fluconazole resistance is reported, and little information is available about the reversibility of resistance status following the withdrawal of fluconazole. METHODS: Repeated antifungal susceptibility tests (ASTs) for fluconazole at a median interval of 3 months between them were evaluated in women with refractory or recurrent VVC patients at the Vaginitis clinic from 2012 to 2021 (10 years) and performed at pH 7 and pH 4.5 using the broth microdilution tests based on the CLSI M27-A4 reference method. RESULTS: Of 38 patients with long-term follow-up with repeat ASTs, 13 patients (13/38, 34.2%) tested at pH 7.0 remained susceptible to fluconazole with MIC ≤2 µg/mL. Nineteen patients (19/38, 50%) remained resistant to fluconazole with MIC ≥8 µg/mL, whereas four (4/38, 10.5%) changed from susceptible to resistant and two (2/38, 5.2%) changed from resistant to susceptible over time. At pH 4.5, among the 37 patients with repeated MIC values, nine (9/37, 24.3%) remained susceptible to fluconazole and 22 (22/37, 59.5%) remained resistant. Three isolates (3/37, 8.1%) changed from susceptible to resistant, while 3 (3/37, 8.1%) changed from resistant to susceptible over time. CONCLUSION: Fluconazole susceptibility in Candida albicans vaginal isolates obtained longitudinally in women with RVVC remains stable with rare reversal of resistance despite azole avoidance.

Vaginal Isolates of Candida glabrata Are Uniquely Susceptible to Ionophoric Killer Toxins Produced by Saccharomyces cerevisiae.

Compared to other species of Candida yeasts, the growth of Candida glabrata is inhibited by many different strains of Saccharomyces killer yeasts. The ionophoric K1 and K2 killer toxins are broadly inhibitory to all clinical isolates of C. glabrata from patients with recurrent vulvovaginal candidiasis, despite high levels of resistance to clinically relevant antifungal therapeutics.

Conventional oral and secondary high dose vaginal metronidazole therapy for recurrent bacterial vaginosis: clinical outcomes, impacts of sex and menses.

PURPOSE: Oral metronidazole therapy is the standard of care for bacterial vaginosis (BV), yet it has alarming rates of recurrence and refractory responses among recurrent BV (RBV) patients. This study addresses whether high dose vaginal metronidazole therapy (HDM) is beneficial in RBV patients who fail after standard of care (SOC) therapy, whether diagnostic test scores proximal to the HDM predict clinical outcome, and whether menses, coitus, or race influences therapy outcome. PATIENTS AND METHODS: A total of 90 patients with RBV were given SOC and tracked 74 for up to 9 months. Refractory or recurrent patients (57) with symptomatic BV were given HDM and followed for up to 8 months. Patients were evaluated by Amsel criteria, Nugent score, and a qPCR assay that assesses the Lactobacillus content. RESULTS: HDM achieved at least short-term remission in 68% of the patients who were refractory to or recurred after SOC and provided a 10-day increase in the mean duration of remission among patients who eventually recurred (p=0.027). Patients with prolonged dysbiosis (pH >5 or Amsel 4) before symptomatic recurrence were more likely to recur after subsequent HDM. Most recurrence happened within 10 days of menses, but sex in this cohort was not associated with clinical outcome. Mean diagnostic BV scores of African American patients in remission were inferior to scores of a small cohort of Caucasian patients in remission. CONCLUSION: Encouraging results obtained with HDM justify a prospective, randomized study to determine if follow-up HDM is beneficial among a broader cohort of women failing conventional oral metronidazole therapy.

Prognostic Indicators of Recurrence of Bacterial Vaginosis.

Following all forms of therapy for bacterial vaginosis (BV), recurrence rates are extremely high. Many diagnostic tests are available that differentiate bacterial vaginosis from other types of vaginal disorders, but none predict recurrence after treatment, nor are any vetted for monitoring ongoing responses to treatment. Our goal was to determine which tests, and at what optimal times, have prognostic value in predicting recurrence. This prospective cohort study monitored 74 highly recurrent BV patients for up to 9 months. Symptomatic BV patients were treated with oral metronidazole and were evaluated at cessation of treatment and monthly. Index tests included Amsel, Nugent, BV Blue, and Affirm VPIII, as well as a quantitative PCR (qPCR)-based test under initial evaluation here. The qPCR-based LbRC ( LactobacillusRelative Composition) assay predicted BV recurrence when performed shortly after oral metronidazole treatment, with both 90% positive predictive values (PPV) and 74% negative predictive values (NPV); the Nugent scores had 93% PPV but poor NPV (57%). No test, at any other visit, was prognostic. The LbRC assay and, to a lesser extent, Nugent tests scored a week after oral metronidiazole predicted recurrence, suggesting that the recurrence in this cohort was predominantly by relapse due to incomplete restoration of eubiosis soon after therapy. This is the first study in an under evaluated population of recurrent BV patients that emphasizes the need for and a pathway to a possible prognostic modality. Given the high recurrence rates of BV, prognostic tests that could influence individualized treatment alternatives are urgently needed.

In vitro activity of the novel echinocandin CD101 at pH 7 and 4 against Candida spp. isolates from patients with vulvovaginal candidiasis.

Background: The novel echinocandin CD101 has stability properties amenable to topical formulation for use in the treatment of acute vulvovaginal candidiasis (VVC) and recurrent VVC (RVVC). CD101 has demonstrated potent antifungal activity at pH 7, but assessment of its activity at the physiological pH of the vaginal environment is needed. Objectives: To evaluate the antifungal activity of CD101 against clinical VVC isolates of Candida spp., including azole-resistant strains, at pH 4. Methods: MIC values of CD101 and comparators (fluconazole, itraconazole, micafungin, caspofungin and anidulafungin) were assessed via broth microdilution. MIC assays were conducted at pH 7 and 4 after 24 and 48 h against a 108 VVC isolate panel of Candida spp., including Candida albicans ( n = 60), Candida glabrata ( n = 21), Candida parapsilosis ( n = 14) and Candida tropicalis ( n = 13). Results: Overall, MIC values of all drugs were slightly higher at pH 4 versus 7 and at 48 versus 24 h of incubation. CD101 MIC values typically exhibited ∼4-fold shifts at pH 4 and were not affected by azole susceptibility. C. parapsilosis susceptibility was the least affected at pH 4 and did not increase for most drugs. Conclusions: CD101 had potent activity against all Candida isolates tested, including azole-resistant strains. Although there was some reduction in activity at pH 4 versus 7, the resulting MIC values were still well below the intravaginal CD101 drug concentrations anticipated to be present following topical administration. These results support continued development of topical CD101 for the treatment of VVC/RVVC.

Effect of pH on in vitro susceptibility of Candida glabrata and Candida albicans to 11 antifungal agents and implications for clinical use.

The treatment of vulvovaginal candidiasis (VVC) due to Candida glabrata is challenging, with limited therapeutic options. Unexplained disappointing clinical efficacy has been reported with systemic and topical azole antifungal agents in spite of in vitro susceptibility. Given that the vaginal pH of patients with VVC is unchanged at 4 to 4.5, we studied the effect of pH on the in vitro activity of 11 antifungal agents against 40 C. glabrata isolates and compared activity against 15 fluconazole-sensitive and 10 reduced-fluconazole-susceptibility C. albicans strains. In vitro susceptibility to flucytosine, fluconazole, voriconazole, posaconazole, itraconazole, ketoconazole, clotrimazole, miconazole, ciclopirox olamine, amphotericin B, and caspofungin was determined using the CLSI method for yeast susceptibility testing. Test media were buffered to pHs of 7, 6, 5, and 4. Under conditions of reduced pH, C. glabrata isolates remained susceptible to caspofungin and flucytosine; however, there was a dramatic increase in the MIC(90) for amphotericin B and every azole drug tested. Although susceptible to other azole drugs tested at pH 7, C. albicans strains with reduced fluconazole susceptibility also demonstrated reduced susceptibility to amphotericin B and all azoles at pH 4. In contrast, fluconazole-sensitive C. albicans isolates remained susceptible at low pH to azoles, in keeping with clinical observations. In selecting agents for treatment of recurrent C. glabrata vaginitis, clinicians should recognize the limitations of in vitro susceptibility testing utilizing pH 7.0.

Trends in antimicrobial resistance of Acinetobacter baumannii isolates from a metropolitan Detroit health system.

A phenotypic and genotypic analysis of Acinetobacter baumannii was conducted from 2003 to 2008 in Detroit, MI. The incidence of A. baumannii increased from 1.7 to 3.7/1,000 patient days during the study period. Susceptibility to ampicillin-sulbactam and imipenem decreased from approximately 90% to approximately 40%. Genotyping revealed polyclonality, suggesting either emergence of multiple resistant strains or spread of a common genetic element. The sharp rise mandates major multidisciplinary interventions to optimize management of this multidrug-resistant pathogen.

Multiechinocandin- and multiazole-resistant Candida parapsilosis isolates serially obtained during therapy for prosthetic valve endocarditis.

Echinocandins are approved for the treatment of candidal infections. In vitro they have been shown to be less potent against strains of Candida parapsilosis than against other Candida spp. This is the first case report describing the development of a secondary multidrug (echinocandin-azole)-resistant Candida strain during therapy.

Vaginitis due to Candida krusei: epidemiology, clinical aspects, and therapy.

Twelve women with vaginal Candida krusei infection were evaluated. In vitro antifungal susceptibility testing and molecular typing were performed. Patients infected with C. krusei frequently had refractory vulvovaginal signs and symptoms that were otherwise indistinguishable from vaginitis due to other yeasts. Patients were 32-63 years old and had previously received multiple courses of antimycotic agents, including fluconazole and miconazole. The most active azole in vitro was clotrimazole, with a 90% minimum inhibitory concentration of 0.25 microg/mL. Four of 6 patients treated with boric acid had clinical and mycological cure. Two dominant genotypes of C. krusei were identified via contour-clamped homogenous electrical field analysis. No major genotypic change was observed in successive isolates from the same patient in most cases, suggesting that these refractory cases were relapses. C. krusei is a rare but important cause of refractory vaginitis and is unique because of its intrinsic resistance to fluconazole.