Genital Candida in Patients with Sexually Transmitted Infections – An Innocent Bystander or a Pathogenic Culprit?.

Abstract

The presence of one STI increases the risk of having concomitant and co-transmission of other STI. An evolving trend of Candida infections in STI patients, showing a transition from harmless colonizers to unrelenting pathogens, is a fine line attributable to extensive repertoire of virulence determinants. The present study was carried out to identify the genital Candida flora prevalent in patients attending sexually transmitted disease (STD) Clinic and to determine the haemolysin and phospholipase activity amongst these isolates. Further, correlation of species of infecting/ prevalent Candida with the co-existing STI was done. A total of 75 consecutive male and female patients, presenting with one or more of the complaints as enunciated by World Health Organization (WHO) in the Syndromic Approach for the diagnosis of STIs, were included in the study. Candida was isolated in significantly higher numbers from patients presenting with discharge (47%) followed by balanitis (30%), and genital ulcer (23%). C. albicans (73%) was predominant isolate in various STIs. Hemolysin index and phospholipase activity of C. albicans was found significantly higher enhancing their pathogenic potential. The study suggests the role of genital inflammation by Candida as a significant cofactor in STI acquisition and existence of genital Candida as colonizer or pathogen. The study provides a rational basis for empirical therapy in STI patients.

Keywords

Candida, sexually transmitted infection, phospholipase, hemolysin.

Introduction

It is well recognized that, the presence of one STI increases the risk of having another, through the same route, as a consequence of mucosal barrier damage and inflammation [1]. Although Candidal vulvo-vaginitis is not always considered a STI, evidence in favor of sexual transmission exists [2]. Whether genital Candida is a commensal or a pathogen, capable of causing substantial morbidity, is not fully understood. The ability of Candida to transform itself from a harmless commensal to an unrelenting pathogen is attributed to an extensive repertoire of virulence determinants, selectively expressed under suitable predisposing conditions [3]. In this study, we investigated the clinical significance of genital Candidaisolated, as a co-pathogen amongst STI patients and determined expression of phospholipase and hemolysin activity, as indicator of pathogenicity.

A prospective study, approved by institutional ethical committee, was conducted on 75 consecutive male and female STI patients, attending STD Clinic, between April 2009 to March 2010. Patients with age ≥ 18 yrs diagnosed with a STI Syndrome, as per “WHO Syndromic Approach for the diagnosis of STI” [4], were included. Detailed history followed by physical and genital examination was undertaken. All patients were managed according to NACO guidelines [5]. Relevant samples were collected from each patient based upon the diagnosis varying from urethral discharge, vaginal discharge and exudates, expressed by gentle compression of fresh unhealed genital ulcer. Samples were subjected to direct microscopy and culture (wherever possible), as per standard laboratory procedures for detecting STI agents [6]. They were further processed for Candidal isolation and identification. HBsAg, HSV-1 & 2 IgM and VDRL tests were performed from serum samples. Patient’s HIV status was determined as per NACO guidelines [7]. Determination and quantification of phospholipase [3] and hemolysin [8] activities were assayed for all Candida isolates. The reference strain included ATCC C. albicans 90028. Twenty healthy non-pregnant women and men, each between ages of 21 and 50, were taken as controls and investigated for genital Candida.

Statistical analysis of continuous quantitative variables, between groups, was tested by unpaired t-test. Associations of presenting complaints with culture positive Candida and phospholipase index were analyzed by Pearson’s Chi-square test of Fisher’s Exact test. Unadjusted odds ratio (OR) and 95% confidence interval (CI) were calculated for STIs with and without concomitant Candida. ANOVA followed by Tukey’s test was used to compare hemolytic index in different Candida species.

Age of the patients ranged from 18 to 62 years, with the maximum in age group of 20-30 years (68%), which represented the maximum sexually active age group.

Distribution of cases according to presenting complaints with candidal culture positivity is given in [Table-1]. Genital ulceration and genital discharge were found to be statistical significant presenting complaint (p < 0.001) amongst male and female STD clinic attendees respectively. Out of 32 (61.5%) patients clinically suspected to have herpes progenitalis, 17 (32.7%) were found to have IgM antibodies against HSV-1 / 2. While 13 (25.1%) patients clinically suspected to have chancre, 11(26.8%) were found to be VDRL reactive [Table-2]. Overall prevalence of genital candidiasis amongst the study group was found to be 34.6%.

Species distribution of Candida in STIs is shown in Figure 1. Favorable odds ratio of 1.438 (CI .540-3.832) was found in patients diagnosed with herpetic ulcer for having coexisting Candida infection. Concomitant Candida, if expressing virulence factors, may increase the severity of disease in such patients. Interspecies comparison of phospholipase and hemolysin activity is tabulated in [Table-3]. It is generally believed that phospholipases situated at hyphal tip, contribute to organisms increased hydrophobicity, adherence to epithelial cells and invasiveness. It is worth noting, C. glabrata isolated from a HIV seropositive patient was found to produce very high amount of phospholipase indicating its pathogenic potential in this immunologically challenged condition. Hemolysin index of C. albicans was significantly higher (p < 0.001) followed by C. glabrata, a finding similar to a study demonstrated by Luo et al [9], suggesting the importance of hemolysin in making C. albicans a more hardy survivor (and subsequently a more common pathogen) on human mucosal surfaces. Candidiasis in association with genital ulcers maybe one such situation, where mucosal damage and inflammation allows Candidal bystander yeast form to undergo a phenotypic change, leading to a prolonged non- healing ulcerative condition.

From the women control group, five were found to harbor C. albicans in their genital flora and none demonstrated phospholipase activity; however two isolates showed hemolysin activity. Of male control group, none were found to harbor Candida.

Our observation highlights that concomitant Candida may be a potential contributor to recurrences and impaired healing of certain patient population especially with viral ulcerative lesions as documented in HIV-HSV co-infection [10]. This mandates thorough workup for identifying hidden Candida co-infection. Given the pathogenic synergy of Candida and STI pathogens, therapy with antifungals is crucial in the routine syndromic management. Molecular tools for strain delineation amongst Candida species as a part of microbial surveillance may help elucidate factors that predict Candida infection preceded by colonization.

Acknowledgement

We are most grateful to the study participants whose cooperation made this study possible.

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