Lack of in vitro resistance of Candida albicans to ketoconazole, itraconazole and clotrimazole in women treated for recurrent vaginal candidiasis

Treatment for recurrent vulvovaginal candidiasis (thrush)

BACKGROUND

Recurrent vulvovaginal candidiasis (RVVC) affects up to 5% of women. No comprehensive systematic review of treatments for RVVC has been published.

OBJECTIVES

The primary objective was to assess the effectiveness and safety of pharmacological and non-pharmacological treatments for RVVC. The secondary objective was to assess patient preference of treatment options.

SEARCH METHODS

We conducted electronic searches of bibliographic databases, including CENTRAL, MEDLINE, Embase, and CINAHL (search date 6 October 2021). We also handsearched reference lists of identified trials and contacted authors of identified trials, experts in RVVC, and manufacturers of products for vulvovaginal candidiasis.

SELECTION CRITERIA

We considered all published and unpublished randomised controlled trials evaluating RVVC treatments for at least six months, in women with four or more symptomatic episodes of vulvovaginal candidiasis in the past year. We excluded women with immunosuppressive disorders or taking immunosuppressant medication. We included women with diabetes mellitus and pregnant women. Diagnosis of RVVC must have been confirmed by presence of symptoms and a positive culture and/or microscopy. We included all drug and non-drug therapies and partner treatment, assessing the following primary outcomes: • number of clinical recurrences per participant per year (recurrence defined as clinical signs and positive culture/microscopy); • proportion of participants with at least one clinical recurrence during the treatment and follow-up period; and • adverse events.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed titles and abstracts to identify eligible trials. Duplicate data extraction was completed independently by two authors. We assessed risk of bias as described in the Cochrane Handbook for Systematic Reviews of Interventions. We used the fixed-effects model for pooling and expressed the results as risk ratio (RR) with 95% confidence intervals (CI). Where important statistical heterogeneity was present we either did not pool data (I² > 70%) or used a random-effects model (I² 40-70%). We used the GRADE tool to assess overall certainty of the evidence for the pooled primary outcomes.

MAIN RESULTS

Studies: Twenty-three studies involving 2212 women aged 17 to 67 years met the inclusion criteria. Most studies excluded pregnant women and women with diabetes or immunosuppression. The predominant species found on culture at study entry was Candida albicans. Overall, the included studies were small (<100 participants). Six studies compared antifungal treatment with placebo (607 participants); four studies compared oral versus topical antifungals (543 participants); one study compared different oral antifungals (45 participants); two studies compared different dosing regimens for antifungals (100 participants); one study compared two different dosing regimens of the same topical agent (23 participants); one study compared short versus longer treatment duration (26 participants); two studies assessed the effect of partner treatment (98 participants); one study compared a complementary treatment (Lactobacillus vaginal tablets and probiotic oral tablets) with placebo (34 participants); three studies compared complementary medicine with antifungals (354 participants); two studies compared 'dermasilk' briefs with cotton briefs (130 participants); one study examined Lactobacillus vaccination versus heliotherapy versus ciclopyroxolamine (90 participants); one study compared CAM treatments to an antifungal treatment combined with CAM treatments (68 participants). We did not find any studies comparing different topical antifungals. Nine studies reported industry funding, three were funded by an independent source and eleven did not report their funding source. Risk of bias: Overall, the risk of bias was high or unclear due to insufficient blinding of allocation and participants and poor reporting. Primary outcomes: Meta-analyses comparing drug treatments (oral and topical) with placebo or no treatment showed there may be a clinically relevant reduction in clinical recurrence at 6 months (RR 0.36, 95% CI 0.21 to 0.63; number needed to treat for an additional beneficial outcome (NNTB) = 2; participants = 607; studies = 6; I² = 82%; low-certainty evidence) and 12 months (RR 0.80, 95% CI 0.72 to 0.89; NNTB = 6; participants = 585; studies = 6; I² = 21%; low-certainty evidence). No study reported on the number of clinical recurrences per participant per year. We are very uncertain whether oral drug treatment compared to topical treatment increases the risk of clinical recurrence at 6 months (RR 1.66, 95% CI 0.83 to 3.31; participants = 206; studies = 3; I² = 0%; very low-certainty evidence) and reduces the risk of clinical recurrence at 12 months (RR 0.95, 95% CI 0.71 to 1.27; participants = 206; studies = 3; I² = 10%; very low-certainty evidence). No study reported on the number of clinical recurrences per participant per year. Adverse events were scarce across both treatment and control groups in both comparisons. The reporting of adverse events varied amongst studies, was generally of very low quality and could not be pooled. Overall the adverse event rate was low for both placebo and treatment arms and ranged from less than 5% to no side effects or complications.

AUTHORS' CONCLUSIONS

In women with RVVC, treatment with oral or topical antifungals may reduce symptomatic clinical recurrences when compared to placebo or no treatment. We were unable to find clear differences between different treatment options (e.g. oral versus topical treatment, different doses and durations). These findings are not applicable to pregnant or immunocompromised women and women with diabetes as the studies did not include or report on them. More research is needed to determine the optimal medication, dose and frequency.

An investigation into the pathogenesis of vulvo-vaginal candidosis

OBJECTIVE

To monitor yeasts isolated from women during and between episodes of recurrent vulvo-vaginal candidosis (VVC) to determine whether vaginal relapse or re-infection occurred.

METHODS

Women presenting at the genitourinary medicine clinic with signs and symptoms of VVC were recruited to the study (n = 121). A vaginal washing, high vaginal swab (HVS) and rectal swab were taken and the women treated with a single 500 mg clotrimazole pessary. Women were asked to re-attend after 1, 4, and 12 weeks, or when the VVC recurred, when vaginal washings and HVS were repeated. Candida isolates recovered were strain typed using the Ca3 probe and their similarity assessed. Antifungal susceptibility to fluconazole and clotrimazole were determined.

RESULTS

Of the women recruited, 47 completed the study, either returning for four visits or suffering a recurrence during the study period. Of the 22 women who experienced recurrence, the same strain was responsible for the initial and recurrent episode in 17 women. For the remaining five women, four had strain replacement and one had a change of species. None of the isolates recovered from the women demonstrated resistance to either clotrimazole or fluconazole.

CONCLUSIONS

Our findings support the theory of vaginal relapse and thus may support the use of more prolonged courses of antifungal therapy initially to increase the chances of eradication of the yeast.

Clinical, cellular, and molecular factors that contribute to antifungal drug resistance

In the past decade, the frequency of diagnosed fungal infections has risen sharply due to several factors, including the increase in the number of immunosuppressed patients resulting from the AIDS epidemic and treatments during and after organ and bone marrow transplants. Linked with the increase in fungal infections is a recent increase in the frequency with which these infections are recalcitrant to standard antifungal therapy. This review summarizes the factors that contribute to antifungal drug resistance on three levels: (i) clinical factors that result in the inability to successfully treat refractory disease; (ii) cellular factors associated with a resistant fungal strain; and (iii) molecular factors that are ultimately responsible for the resistance phenotype in the cell. Many of the clinical factors that contribute to resistance are associated with the immune status of the patient, with the pharmacology of the drugs, or with the degree or type of fungal infection present. At a cellular level, antifungal drug resistance can be the result of replacement of a susceptible strain with a more resistant strain or species or the alteration of an endogenous strain (by mutation or gene expression) to a resistant phenotype. The molecular mechanisms of resistance that have been identified to date in Candida albicans include overexpression of two types of efflux pumps, overexpression or mutation of the target enzyme, and alteration of other enzymes in the same biosynthetic pathway as the target enzyme. Since the study of antifungal drug resistance is relatively new, other factors that may also contribute to resistance are discussed.

Clinical and cost considerations in the pharmacotherapy of vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is a frequent cause of morbidity in women of reproductive age. Most women will experience 1 or 2 episodes in their lifetime, but a smaller population develop chronic recurrent disease. There are few data on cost or pharmacoeconomic considerations in the management of this condition. The disease does not usually result in long term disability, loss of employment or death, but could affect a woman's work performance through irritability, frustration and unhappiness. This review attempts to estimate the least costly programme or regimen (as the efficacy of different regimens is similar) that would be applicable to patients, third-party payers and society. Nonprescription or over-the-counter (OTC) antifungal preparations could have an impact on overall cost in the management of VVC. In the management of infrequent acute VVC, an OTC preparation would be least costly to the healthcare system (provided that the diagnosis was correct). The strategies used to control symptoms in patients with chronic recurrent VVC should be based on the frequency of recurrent episodes. For patients with less than 12 episodes a year, empirical self-treatment at the onset of symptoms with an OTC agent (e.g. intravaginal clotrimazole 500mg) is less costly and preferable to patients than monthly prophylaxis. Patients with a greater frequency of recurrences may benefit from monthly, daily or twice weekly prophylaxis. At present, for very frequent recurrences, intravaginal clotrimazole 200mg twice weekly appears to be as effective as daily oral ketoconazole, and may be safer and less costly. However, because of the lack of prospective controlled studies, most of these recommendations are based on hypothetical reasonings. Furthermore, the disadvantages of OTC antifungals include the potential for overuse and inappropriate use, possibly resulting in the delayed diagnosis and treatment of other conditions. On balance, OTC preparations may provide patients with faster and more economical care, and improve healthcare delivery.

Itraconazole. A reappraisal of its pharmacological properties and therapeutic use in the management of superficial fungal infections

Itraconazole is an orally administered triazole antifungal agent. Its spectrum of activity includes dermatophyte, dimorphic and dematiaceous fungi, yeasts, and some moulds. In clinical trials, mycological cure was attained in approximately 70 to 80, > or = 70 and > or = 80% of patients with, respectively, fingernail and toenail onychomycosis (200 mg/day for 3 months), dermatophytosis (100 mg/day for 2 to 4 weeks) and vaginal candidiasis (400 mg/day for 1 day or 200 mg/day for 3 days). Approximately 20 to 30% of patients with onychomycosis may relapse after completion of therapy; relapse rate data are limited for the other indications. Recently developed intermittent regimens of itraconazole (400 mg/day for 1 week per month for 3 to 4 months) appear to have similar efficacy to standard regimens in the treatment of onychomycosis. Shorter, higher dosage itraconazole treatment regimens (200 or 400 mg/day for 1 week) are also beneficial in dermatomycoses. Discrepancies and limitations of study design hamper conclusions about efficacy relative to other antifungal drugs. Newer intermittent and short course higher dosage itraconazole regimens have also not been evaluated in comparative studies. Available studies show that the efficacy of itraconazole appears to be greater than that of griseofulvin, but similar to or lower than that of terbinafine in patients with dermatophyte onychomycosis or cutaneous fungal infections. Moreover, the efficacy of itraconazole may be similar to or lower than that of fluconazole in the treatment of cutaneous mycoses. Comparative data from patients with acute vaginal candidiasis suggest that itraconazole is at least as effective as intravaginal clotrimazole and oral fluconazole, and superior to intravaginal econazole. These results require confirmation. Prescription-event monitoring data indicate that itraconazole is generally well tolerated. Gastrointestinal disturbances, dizziness and headache occur most commonly; liver toxicity has been rarely described. Its usefulness in some clinical situations may be limited because of its ability to interact with various therapeutic agents. In conclusion, itraconazole along with other established agents should be considered a first-line treatment for patients with extensive or recalcitrant cutaneous fungal infections, mixed dermatophyte and Candida onychomycosis or vaginal candidiasis. It is currently considered a second-line drug for dermatophyte onychomycosis; the use of newer intermittent itraconazole treatment regimens may, however, extend its role in the management of this condition. Although itraconazole offers greater benefit than conventional therapies (griseofulvin and ketoconazole) in terms of efficacy and tolerability, wider clinical experience is required to determine its merits relative to the newer agents, terbinafine and fluconazole.