Candida species isolated from the vaginal mucosa of HIV-infected women in Salvador, Bahia, Brazil

ORIGINAL ARTICLE

Candida species isolated from the vaginal mucosa of HIV-infected women in Salvador, Bahia, Brazil

Paula Matos Oliveira^I; Rita Elizabeth Mascarenhas^II; Claire Lacroix^III; Suzana Ramos Ferrer^II; Rone Peterson C Oliveira^IV; Elaine Andrade Cravo^V; André P Ribeiro Alves^V; Maria Fernanda Rios Grassi^VI

^IObstetrics and Gynecology Specialist; PhD student of Postgraduate Program on Medicine and Human Health, Escola Bahiana de Medicina e Saúde Pública (EBMSP), Salvador, Bahia, Brazil

^IIPhD; Professor of Microbiology, EBMSP, Salvador, Bahia, Brazil

^IIIPhD; Laboratoire de Mycologie-Parasitologie, Paris, France

^IVMSc; Gynecology Assitant Professor, EBMSP, Salvador, Bahia, Brazil

^VScientific initiation student, EBMSP, Salvador, Bahia, Brazil

^VIPhD; Chief of Laboratório Avançado de Saúde Pública, FIOCRUZ, Bahia, Brazil

^{Correspondence to}

ABSTRACT

BACKGROUND: Vulvovaginal candidiasis (VVC) is the second most common vaginal infection. HIV-infection is a risk factor for this infection.

OBJECTIVE: To determine the frequency of VVC and to describe the main Candida species isolated and their susceptibility to antifungal drugs in HIV-infected patients, compared to HIV-uninfected women in Salvador, Brazil.

METHODS: Cross-sectional study including a group of 64 HIV-infected women and 76 uninfected women, followed up at the AIDS reference center and at the Gynecological Clinic of Escola Bahiana de Medicina e Saúde Pública (Salvador, Bahia, Brazil).

RESULTS: Frequency of Candida spp. was higher in HIV-infected women (29.7%) than in HIV-uninfected controls (14.5%) (p = 0.02). The odds ratio value for vulvovaginal candidiasis in HIV-infected patients was 2.6 (95% CI: 1.07 - 6.32 p = 0.03). Candida albicans was the most commonly isolated species in both HIV-infected (52.3%) and uninfected women (85.7%), followed by C. parapsolis in 17.6% and 14.3%, respectively. In HIV-infected women, C. glabrata, C. parapsilosis, and a coinfection of C. albicans and C. glabrata were also identified. There was no significant difference between Candida species isolated from the vaginal mucosa of women with VVC and colonization of the vaginal mucosa of HIV-infected and HIV-uninfected women. One C. glabrata isolate from an HIV-infected patient was resistant to fluconazole and other two isolates exhibited a dose-dependent susceptibility.

CONCLUSION: Our results confirm a higher frequency of Candida spp. isolated from the vaginal mucosa of HIV-infected women and a broader spectrum of species involved. Only Candida glabrata isolates showed decreased susceptibility to fluconazole.

Keywords: HIV; Candida; candidiasis, vulvovaginal.

INTRODUCTION

Vulvovaginal candidiasis (VVC) is one of the most frequent vaginal infections in the world.^1,2 It is estimated that 75% of women will have VVC at least once in their lifetime.^3,4 Clinical signs and symptoms of this infection include itching, white discharge, edema, and erythema of the vulva.^4-6Candida albicans, a saprophyte present in the vaginal mucosa, is isolated in 80% of VVC cases.^7,8 Factors which predispose to VVC include: pregnancy, uncontrolled diabetes mellitus, corticosteroids or systemic/vaginal antibiotic therapy, HIV infection, and Candida vaginal colonization (CVC).^9,10

The frequency of VVC caused by other Candida species, such as Candida tropicalis, Candida glabrata, and Candida krusei is increasing, especially in HIV-infected women.^5,8,11C. albicans and C. glabrata are responsible for the majority of VVC cases in HIV-infected women.^10,12 Although resistance to azoles antifungal therapy is rare in C. albicans isolates (1%), it is becoming commonplace among C. glabrata isolates (up to 15%) as well as among other non-albicans species.^5,10,13,14

Few studies in Brazil have assessed the prevalence of VVC in HIV-infected women undergoing highly active antiretroviral therapy (HAART) treatment.¹⁵ The aim of this study was to determine the frequency of VVC and to describe the main Candida species isolated in HIV-infected patients, compared to HIV-uninfected women in Salvador, Brazil. In addition, the susceptibility of Candida species to antifungal drugs was evaluated.

MATERIAL AND METHODS

Study population and procedure

A group of sixty-four HIV-infected women receiving care at the AIDS reference center of Bahia (Centro Especializado em Diagnóstico, Assistência e Pesquisa, CEDAP) and 76 HIV-uninfected women from the Gynecology Clinic of Escola Bahiana de Medicina e Saúde Pública (Salvador, Bahia, Brazil) were included in this study, between May 2006 and May 2007.

Patients were sequentially enrolled at the moment of the medical appointment. Inclusion criteria were women aged more than 18 years old, sexually active, positive serology for HIV (HIV group) or negative (control group). Exclusion criteria were: pregnancy or post-partum, intra-vaginal treatment thirty days prior to vaginal collection, vaginal bleeding, sexual intercourse or vaginal douching within the 48 hours preceding vaginal sample collection.

The study was approved by the Institutional Research Boarding of the Fundação Oswaldo Cruz Bahia (Fiocruz - Bahia). All patients signed an informed consent form prior to admission.

Specimen collection

Demographic and clinical data were obtained by specific standardized data collection forms. CD4+ T lymphocytes count and HIV viral load values were obtained from medical records. Vaginal samples were collected with sterile swabs, during gynecological examination. Samples were cultured on Sabouraud's agar (BD-Difco), incubated at 35ºC for 48 h, and a direct examination was performed. Yeasts isolates were sub-cultured on CHROMagar Candida (Beckton Dickinson) in order to identify C. albicans and mixtures of yeasts. All C. albicans isolates were screened with Bichro-Dubli^® (Fumouze) in order to identify C. dubliniensis. Other Candida species were identified with ID32CAux^® (BioMérieux). Minimal inhibitory concentrations (MICs) were determined by the E-Test^® method with C. parapsilosis ATCC 22019 as control. After 24 hours of incubation, an elliptical zone of inhibition was produced and the point at which the ellipse meets the strip gives a reading for the MIC of the drug.

Candida vaginal colonization was defined as culture isolation of yeasts from asymptomatic women. Women with a positive culture were considered to have VVC if they reported symptoms (vaginal itching, burning, and/or discharge) at the time of the medical appointment.

Statistical analysis

Frequencies of Candida spp. of HIV-infected women were compared to those of the control group by using t tests for continuous variables and Chi-square tests or Fisher's exact test for categorical variables. A multiple logistic regression model was used to evaluate the prediction capacity of each independent variable in the occurrence of the expected condition. Unadjusted odds ratios (ORs) were initially calculated to screen for inclusion in the multivariate model; variables that exhibited at least moderate association (p = 0.10) with the outcome in the presence of these design variables were considered for inclusion in the final models. Statistical analysis was done with the SPSS (Statistical Package for the Social Sciences) 13.0.

RESULTS

The median age of HIV-infected patients was similar to that of the uninfected control group. Age at time of first sexual intercourse was lower in HIV-infected women (16.2 ± 4.0 years) compared to the control group (17.5 ± 3.9 years) [p = 0.05]. The number of lifetime sexual partners and the frequency of reported sexually transmitted diseases were significantly higher in the HIV-infected group, compared to uninfected patients. Thirty-four HIV-infected women (56.3%) were treated with HAART. The mean CD4+ T lymphocytes count was 644 ± 551 cells/mm³ and mean HIV viral load was 3.9 ± 4.3 log₁₀ copies/mL.

Candida spp. isolation from the vaginal mucosa was more frequent in HIV-infected patients (29.7%), compared to uninfected women (14.5%) (p = 0.02). However, the frequency of VVC and Candida spp. colonization were similar in both HIV-infected and uninfected women (p = 0.95) (Table 1). The odds ratio value for the presence of Candida spp. in vaginal mucosa of HIV-infected patients was 2.6 (95% CI: 1.07 - 6.32, p = 0.03), after adjusting for variables (Table 2).

Candida spp. identification was possible in 24 vaginal samples (17 from HIV-infected patients and 7 from uninfected women) (Table 3). C. albicans was the most frequent species isolated in both HIV-infected (52.9%) and uninfected women (85.7%). In HIV-infected women were also identified the following species: C. glabrata, C. parapsilosis, C. dubliniensis and a coinfection of C. albicans and C. glabrata. In the HIV-uninfected group, the only species isolated were C. albicans and C. parapsilosis.

In both HIV-infected and uninfected women, there was no significant difference observed in the frequency of a particular species of Candida isolated from the vaginal mucosa and the presence of VVC, nor was there a difference in the frequency of a particular species of Candida colonizing the vaginal mucosa (Table 4).

Only one out of 24 yeast isolates, an isolate of C. glabrata from an HIV-infected patient, was resistant to fluconazole (MIC > 256 mg/L). Two C. glabrata isolates exhibited a dose-dependent susceptibility to fluconazole (MIC = 24 and 48 mg/L) (Table 5).

DISCUSSION

This study assessed for the first time the prevalence of VVC and the main Candida species found in vaginal mucosa of HIV-infected women, in Salvador-Bahia, Brazil. The main finding of our study was the higher frequency of Candida spp. in vaginal mucosa of HIV-infected women than HIV-uninfected, but the frequency of VVC was similar in both groups. These results were expected since the majority of the HIV-infected patients enrolled in this study were on HAART and had CD4+ T-cell counts higher than 500 cells/mm³. Indeed, the risk of colonization with Candida species in HIV-infected women with CD4+ T-cell counts below 200 cells/mm³ is three times higher, compared to immunocompetent HIV-infected or HIV-uninfected women.^16,17 Similar prevalence of VVC (23.5%) was found in patients from a cohort of 458 HIV-infected patients under antiretroviral therapy followed in Rio de Janeiro-Brazil. However, the authors did not identify species of Candida and there was no uninfected-control group.¹⁵ The prevalence of Candida spp. isolated from the vaginal mucosa is variable. In Italy, 16.8% of HIV-infected women have Candida spp. in vaginal mucosa,¹⁰ while in the United States 35% of HIV-infected women had vaginal positive culture for Candida spp. (EUA).¹⁸ Such variation could be explained by differences in the immune status of patients involved or by the presence of additional risk factors to Candida infection, such as a decreased number of CD4+ T-cells or concomitant antibiotic therapy.¹⁸

There is scant information about the frequency of non-albicans species in vaginal mucosa of HIV-infected women in Brazil. In the present study, C. albicans was the most frequent species isolated from the vaginal mucosa in both HIV-infected and uninfected women. In other countries such as Italy and the United States, the frequency was higher ranging from 81% to 92%, compared to that found in our study (52.9%).^10,11,18 In HIV-uninfected patients, our data was similar to other studies performed in Brazil, which describe the prevalence of C. albicans isolated in vaginal samples ranging from 60% to 80%^19,20 and in other countries where the prevalence of C. albicans in vaginal samples ranges between 80% to 90%.^1,11,21,22 A higher diversity of non-albicans species was found in HIV-infected patients compared to uninfected controls. C. glabrata was the most frequent non-albicans species isolated in HIV-infected patients, followed by C. parapsilosis.

In accordance with other studies, there was no relationship found between symptoms and isolated yeast species.²³ No correlation could be established between the level of CD4+ T-cell counts, the amount of HIV viral load, and the frequency of VVC in HIV-infected patients. These results were expected because of the observational nature of our study and the small sample size.

Regarding the susceptibility of Candida species to antifungal drugs, isolated yeasts were susceptible to Amphotericin B, Flucytosine, Voriconazole, and Caspofungin. Only three isolates had dose-dependent susceptibility or resistance to fluconazole, all of these were C. glabrata present in the vaginal mucosa of HIV-1-infected patients. These data are in agreement with other studies^23-25 that described azole refractory vaginitis caused by non-albicansCandida, particularly by C. glabrata.²³ Non-albicansCandida infections frequently require the use of non-azole therapy, including topical therapy with boric acid, Flucytosine, or Amphotericin B.^24,26

In summary, our study found higher prevalence of Candida spp. in vaginal mucosa of HIV-infected patients than uninfected women. Thus, these patients could benefit from a periodic gynecological examination and VVC screening, even when undergoing HAART treatment. Although the species of C. albicans is the most frequent, it is evident the emergence of non-albicansCandida species, including C. glabrata with intrinsic resistance to azoles. Therefore, alternative agents to treat VCC caused by C. glabrata should be considered.

Submitted on: 11/17/2010

Approved on: 02/17/2011

We declare no conflict of interest.

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Publication Dates

• Publication in this collection
  06 June 2011
• Date of issue
  June 2011

History

• Accepted
  17 Feb 2011
• Received
  17 Nov 2010