Azole resistance among oral Candida species isolates from AIDS patients under ketoconazole exposure

Vulvovaginal candidiasis in pregnant women attending a tertiary care centre in North-Eastern India

BACKGROUND

Candida colonisation in vagina was found to be 20 %, rising to 30 % during pregnancy. According to studies, the prevalence of VVC during pregnancy is higher than healthy women. During pregnancy, candidal colonisation increases, both symptomatic and asymptomatic. However, the difference between strains causing symptomatic infection and those that cause asymptomatic infection is unknown.

OBJECTIVE

This study aimed to compare the virulence factors of Candida VVC isolates from symptomatic and asymptomatic pregnant women.

METHODS

The study included 120 pregnant women- 60 symptomatic and 60 asymptomatic, who presented to the Obstetrics and Gynaecology Outpatient Department with vaginitis symptoms. High vaginal swabs from the patient and used for gram stain, direct wet mount, pH detection and fungal culture in SDA with and without antibiotics. Germ tube tests, growth in CMA, and HiCrome Candida Differential Agar were used to identify yeast colonies grown in culture. The isolates were then examined for virulence factors like biofilm formation, phospholipase, coagulase, and hemolysin. Antifungal susceptibility was determined using E-test.

RESULTS

The current study reveals a high prevalence of Vulvovaginal Candidiasis in pregnant women(35 %). Asymptomatic patients had lower proportion of VVC than symptomatic patients. Non albicans Candida(NAC) outnumbered Candida albicans. Although Candida albicans growth was predominant in asymptomatic patients. Virulence studies revealed that Candida spp. isolated from symptomatic patients expressed a higher proportion of virulence factors. Besides NAC has higher proportion of expressing virulence factors than Candida albicans and has higher propensity to cause infection especially in symptomatic pregnant women. Antifungal susceptibility testing shows Itraconazole to be most sensitive for VVC treatment but Candida albicans was most susceptible to fluconazole while NAC had the least.

CONCLUSIONS

The study emphasizes the importance of routine screening of symptomatic pregnant women for VVC, as syndromic treatment will increase antifungal resistance, particularly in NAC.

Synergistic Interaction of Certain Essential Oils and Their Active Compounds with Fluconazole against Azole-resistant Strains of Cryptococcus neoformans

OBJECTIVES

This study investigated the anti-cryptococcal potential of certain essential oils (EOs)/compounds alone and in combination with fluconazole.

MATERIALS AND METHODS

We investigated the antifungal activity of oils of Cinnamomum verum, Cymbopogon citratus, Cymbopogon martini, and Syzygium aromaticum, and their major active ingredients cinnamaldehyde, citral, eugenol, and geraniol against clinical and standard strains of Cryptococcus neoformans (CN). Disc diffusion, broth microdilution, checkerboard methods, and transmission electron microscopy were employed to determine growth inhibition, synergistic interaction, and mechanism of action of test compounds.

RESULTS

EOs/compounds showed pronounced antifungal efficacy against azole-resistant CN in the order of cinnamaldehyde > eugenol > S. aromaticum > C. verum > citral > C. citratus > geraniol ≥ C. martini, each exhibiting zone of inhibition >15 mm. These oils/compounds were highly cidal compared to fluconazole. Eugenol and cinnamaldehyde showed the strongest synergy with fluconazole against CN by lowering their MICs up to 32-fold. Transmission electron microscopy indicated damage of the fungal cell wall, cell membrane, and other endomembranous organelles.

CONCLUSION

Test oils and their active compounds exhibited potential anti-cryptococcus activity against the azole-resistant strains of CN. Moreover, eugenol and cinnamaldehyde significantly potentiated the anti-cryptococcal activity of fluconazole. It is suggested that multiple sites of action from oils/compounds could turn static fluconazole into a cidal drug combination in combating cryptococcosis.

ESCMID* guideline for the diagnosis and management of Candida diseases 2012: patients with HIV infection or AIDS

Mucosal candidiasis is frequent in immunocompromised HIV-infected highly active antiretroviral (HAART) naive patients or those who have failed therapy. Mucosal candidiasis is a marker of progressive immune deficiency. Because of the frequently marked and prompt immune reconstitution induced by HAART, there is no recommendation for primary antifungal prophylaxis of mucosal candidiasis in the HIV setting in Europe, although it has been evidenced as effective in the pre-HAART era. Fluconazole remains the first line of therapy for both oropharyngeal candidiasis and oesophageal candidiasis and should be preferred to itraconazole oral solution (or capsules when not available) due to fewer side effects. For patients who still present with fluconazole-refractory mucosal candidiasis, oral treatment with any other azole should be preferred based on precise Candida species identification and susceptibility testing results in addition to the optimization of HAART when feasible. For vaginal candidiasis, topical therapy is preferred.

Anti-candidal activity of essential oils alone and in combination with amphotericin B or fluconazole against multi-drug resistant isolates of Candida albicans

Therapy for candidiasis is becoming problematic due to the toxicities of currently available antifungal agents and the increasing prevalence of resistance among the etiologic agents. Therefore, new antifungals and alternative approaches are needed. In this study, 20 fluconazole-resistant strains of Candida albicans were found to have varying levels of resistance to other azoles, i.e., itraconazole (MIC of 4-128 μg/ml) and ketoconazole (2-256 μg/ml). In addition, 13 of these isolates appeared resistant to amphotericin B (32-128 μg/ml). A total of 21 plant essential oils were screened for their antifungal activity against these multi-drug resistant isolates. The oils of Cymbopogon martini, i.e., citral and cinnamaldehyde, exhibited strong inhibitory activity with minimum inhibitory concentrations (MIC(50)) ranging from 90-100 μg/ml. The test oils were more effective than fluconazole and amphotericin B in inhibiting azole- and amphotericin B-resistant, as well as amphotericin B-susceptible isolates. The test oils and especially eugenol, exhibited significant synergy with fluconazole or amphotericin B against the test isolates. These findings suggest the possible effective use of certain oils alone or in combination with fluconazole or amphotericin B, against multi-drug resistant isolates of C. albicans.

Virulence Factors and Anti Fungal Sensitivity Pattern of Candida Sp. Isolated from HIV and TB Patients

The study comprised of 60 Candida spp., 50 isolates from HIV and TB positive individuals (immunocompromised) and 10 isolates from non-HIV and -TB patients (immunocompetent). Among the 60 Candidal isolates, 83.3% were identified as C. albicans, 11.6% as C. glabrata and rest 5% as C. krusei. There is no study in production pattern of extracellular enzymes of Candida spp. isolated from HIV and TB patients in comparison with non-HIV and -TB patients in India. The comparison of phospholipase activities showed that there was a significant difference between the groups at (P = 0.001). The non-HIV and -TB groups of C. glabrata and C. krusei did not show detectable phospholipase activity when compared to the HIV and TB groups. The mean difference in the phospholipase activities of these two groups was significant (P = <0.001). Candida spp. of both the groups do not possess the ability to hydrolyze gelatin. All the strains possessed the ability to show alpha haemolysis. Even though it had shown alpha haemolysis, the significant difference in haemolytic activity was observed only in C. albicans (P = <0.001). None of the isolates from the two groups possessed the ability to hydrolyze gelatin. In the resistance profile of Candida spp., C. albicans of HIV and TB groups had shown resistance to fluconazole, Itraconazole, ketaconazole, nystatin but showed 100% sensitivity towards amphotericin-B. The isolates of C. krusei and C. glabrata showed no resistance to any of the drugs tested. In the case of, non-HIV and -TB patients the resistance pattern was low.

Effect of amine fluoride-stannous fluoride preparations on oral yeasts in the elderly: a randomised placebo-controlled trial

OBJECTIVES

Oral yeast infections are an emerging problem among medically compromised and frail elderly. Antifungal drug resistance is also increasing because of an increase in non-albicans Candida strains in these populations. We therefore set out to study, in the randomised-controlled trial setting if the use of a topical amine fluoride-stannous fluoride combination (AmF-SnF2) could control oral Candida growth in the elderly. The hypothesis was based on earlier findings showing that in vitro this combination had antifungal efficacy.

METHODS

A total of 194 nursing home residents were randomised to receive either the test mouth rinse and toothpaste or a placebo twice daily for 8 months. Of these, 136 completed the trial. Saliva samples were taken using the oral rinse method, cultivated and the strain level identified with routine microbial methods. Compliance and use of preparations was assessed by a nurse.

RESULTS

Significantly at the end of the trial, less mucosal lesions were observed in the test group in comparison to controls. Total bacterial count decreased in both the groups during the trial. Candida albicans was the most prevalent strain detected both at baseline and 8 months later. Only a few subjects carried non-albicans strains. The AmF-SnF2 did not significantly affect mean oral Candida counts, but median Candida counts were reduced in the AmF-SnF2 group while an increase was seen in the placebo group. However, the differences observed were not statistically significant. Compliance among the regular elderly users slightly increased during the trial for both the groups.

CONCLUSION

The number of subjects with high Candida counts decreased in the AmF-SnF2 group. Hence, the fluoride combination might be useful as a support therapy for oral candidiasis. Prevalence of non-albicans Candida strains was low in this population.

In vitro activities of retigeric acid B alone and in combination with azole antifungal agents against Candida albicans

The vitro antifungal activity of retigeric acid B (RAB), a pentacyclic triterpenoid from the lichen species Lobaria kurokawae, was evaluated alone and in combination with fluconazole, ketoconazole, and itraconazole against Candida albicans using checkerboard microdilution and time-killing tests. The MICs for RAB against 10 different C. albicans isolates ranged from 8 to 16 microg/ml. A synergistic action of RAB and azole was observed in azole-resistant strains, whereas synergistic or indifferent effects were observed in azole-sensitive strains when interpreted by a separate approach of the fractional inhibitory concentration index and DeltaE model (the difference between the predicted and measured fungal growth percentages). In time-killing tests, we used both colony counts and a colorimetric assay to evaluate the combinational antifungal effects of RAB and azoles, which further confirmed their synergistic interactions. These findings suggest that the natural product RAB may play a certain role in increasing the susceptibilities of azole-resistant C. albicans strains.

Oral health and morbidity--implications of oral infections on the elderly

Detrimental effects of oral infections on general health have been known for almost 3000 years. Modern studies, however, have cast new light on the pathogenic mechanisms by which oral infections appear to link with morbidity and mortality. In particular, among the elderly, poor dental health seems to associate with all-cause mortality. This review aims to provide an overview of present knowledge of these issues, starting from dental bacteraemia, oral mucosal infections and problems of drug resistance and, briefly, discussing what is known about the link between oral health and some systemic diseases such as atherosclerosis and type-2 diabetes. The main conclusions are that scientific evidence is still weak on these interactions and that the elderly should be better taken into account when planning future studies. Functions of the body differ in the frail and diseased from those of the young. Consequently, novel prevention and treatment strategies should be developed and properly tested for combating oral infections in elderly populations. Specific suggestions for further research are outlined.

What defines the quality of patient care in tinea pedis?

OBJECTIVES

The aim of this study has been to evaluate patients with tinea pedis for their demographic data and attitudes affecting the treatment of disease, and to compare the in vitro activity of 10 antifungal agents and to relate them to their in vivo activity.

METHODS

Patients with positive mycological examination were enrolled in the study, and a questionnaire comprised of 22 questions was administered. A mycological culture was carried out for each specimen. The antifungal susceptibility of the subcultured species was determined for griseofulvin, terbinafine, ciclopiroxolamine, fluconazole, ketoconazole, itraconazole, bifonazole, sulconazole, oxiconazole and miconazole with microdilution.

RESULTS

Mycological cultures were carried out from 59 patients and there were 35 positive cultures (59.3%). The dermatophytes were Trichophyton rubrum (n = 25) and Trichophyton mentagrophytes (n = 3). The yeasts were Candida albicans (n = 7), Candida glabrata (n = 1) and Trichosporon (n = 2). In the minimum inhibitory concentration (MIC) study, the mean +/- standard error of the mean (SEM) MICs of the antifungals for T. rubrum were as follows: terbinafine 0.01 +/- 0.003, oxiconazole 0.16 +/- 0.05, sulkonazole 0.31 +/- 0.05, miconazole 0.45 +/- 0.15, itraconazole 0.74 +/- 0.01, ketokonazole 1.03 +/- 0.17, ciclopiroxolamine 1.30 +/- 0.12, bifonazole 1.94 +/- 0.51, griseofulvin 4.87 +/- 0.61, and fluconazole 17.91 +/- 3.67 microg/mL.

CONCLUSION

Our study supports that azoles could be used as first-line treatment, as oxiconazole is very effective for both dermatophytes and C. albicans. Correlation between in vitro results and clinical outcomes of cases of dermatophytes is still to be established and interpretive breakpoints defined, in order to increase the quality of patient care in tinea pedis.

In vitro antifungal effect of amine fluoride-stannous fluoride combination on oral Candida species

OBJECTIVE

The combination of amine fluoride and stannous fluoride (AmF/SnF2) was, by chance, found to be antifungal in a clinical trial. This study investigated its effect on pathogenic Candida species with the hypothesis that the antifungal action on different species is variable.

MATERIALS AND METHODS

Growth inhibition effect of Meridol mouth rinse which contains 250 ppm AmF/SnF2 was evaluated on 43 reference and clinical strains of Candida albicans, C. dubliniensis, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis. Meridol base solution without AmF/SnF2 was used as a negative control.

RESULTS

Undiluted Meridolmouth rinse killed most study strains within a few minutes. In ascending order, C. parapsilosis, C. tropicalis, C. albicans, C. glabrata, C. krusei and C. dubliniensis showed higher resistance against AmF/SnF2 than C. guilliermondii.

CONCLUSION

AmF/SnF2 could be used as a potent adjunct to antifungal therapy for oral yeasts. Although different Candida species demonstrated variable sensitivity the most prevalent oral yeast C. albicans appeared sensitive to the AmF/SnF2 combination.

Is a vaccine needed against Candida albicans?

The development of a useful Candida vaccine is a distinct possibility despite the fact that individuals with a lifetime of commensal sensitization do not develop sterile immunity to the organism. An effective Candida vaccine would be invaluable in preventing hematogenously disseminated candidiasis, as well as mucocutaneous disease. This review is a discussion of our current understanding of the interplay between commensal and pathogenic forms of Candida albicans and approaches toward active and passive immunoprevention against candidiasis.

Vulvovaginal candidiasis in children and adolescents with type 1 diabetes mellitus

In this prospective study we investigated the frequency of vulvovaginal candidiasis, the results of yeast cultures and detection of ketoconazole resistance in female children and adolescents with type 1 diabetes mellitus (DM1). The study consisted of 35 patients with DM1 (age 1.7-20 years) and 22 controls (age 1.5-18 years). Age, duration of DM1 and evidence of genital symptoms were recorded initially. After a pelvic examination, two separate swabs and samples for blood glucose and hemoglobin A1c (HbA1c) were taken. One of the swabs was used for direct examination and the second was placed on Sabouraud's dextrose agar and incubated. In vitro susceptibility of Candida species to ketoconazole was established by using Etest (AB B1ODISC). Candida species were isolated in 32 of 61 (52.5%) swabs of patients with DM1 and five of 22 (18.2%) of the control group. The predominant Candida species isolated from patients with DM1 were C. albicans (72.7%), C. glabrata (22.7%), C. tropicalis (2.3%), and C. parapsilosis (2.3%). The mean HbA1c in diabetic patients from whom Candida species were isolated was significantly higher than that of patients without Candida infection (p = 0.002). Most of the C. glabrata isolates were significantly resistant to ketoconazole. During the follow-up of patients with DM1, genital candidiasis is generally overlooked. It should not be forgotten that species other than C. albicans might cause genital candidiasis.

Leucinostatin-A loaded nanospheres: characterization and in vivo toxicity and efficacy evaluation

Leucinostatin A (Leu-A) is a nonapeptide exerting a remarkable activity especially against Candida albicans and Cryptococcus neoformans; nevertheless, its employment is limited due its toxicity. Therefore, we recently developed liposomal formulations, as suitable delivery systems, in order to increase its therapeutic index. However, liposomes present disadvantages related to their long-term instability. For this reason poly(lactic-co-glycolic) nanospheres (NS) were chosen as alternative colloidal carriers for Leu-A delivery. NS were formulated by spontaneous emulsification solvent diffusion method. This study investigates the effects of different parameters on drug encapsulation efficiency and particle size as well. The best preparation obtained was also characterized for its in vitro release, in vivo acute toxicity (LD50), and effectiveness against C. albicans in mice. In vitro release was performed over 100 h and resulted sufficiently sustained with more than 93% of the peptide released. Acute toxicity showed that the LD50 was increased more than 18-fold and the study on systemic candidiasis models revealed high effectiveness of the NS in reducing either the growth of fungal colonies in infected mice liver or in the mortality index. In conclusion, we can propose that Leu-A loaded NS could represent a new promising therapeutic system against Candida infection.

Candida dubliniensis identification in Brazilian yeast stock collection

We investigated the presence of Candida dubliniensis among isolates previously identified as Candida albicans and maintained in a yeast stock collection from 1994 to 2000. All isolates were serotyped and further evaluated for antifungal susceptibility profile. After doing a screening test for C. dubliniensis isolates based on the capability of colonies to grow at 42 C, its final identification was obtained by randomly amplified polymorphic DNA (RAPD) analysis using three different primers. A total of 46 out of 548 screened isolates did not exhibit growth at 42 C and were further genotyped by RAPD. Eleven isolates were identified as C. dubliniensis with RAPD analysis. Regarding serotypes, 81.5% of C. albicans and all C. dubliniensis isolates belonged to serotype A. Of note, 9 out of 11 C. dubliniensis isolates were obtained from patients with acquired immunodeficiency syndrome (Aids) and all of them were susceptible to azoles and amphotericin B. We found 17 (3%) C. albicans isolates that were dose-dependent susceptibility or resistant to azoles. In conclusion, we found a low rate of C. dubliniensis isolates among stock cultures of yeasts previously identified as C. albicans. Most of these isolates were recovered from oral samples of Aids patients and exhibited high susceptibility to amphotericin B and azoles. C. albicans serotype A susceptible to all antifungal drugs is the major phenotype found in our stock culture.

Has antifungal susceptibility testing come of age?

The in vitro susceptibility of an infecting organism to the antimicrobial agent selected for therapy is one of several factors that influence the likelihood that therapy for an infection will be successful. To appreciate the value of antifungal susceptibility testing, it is helpful to review the overall predictive utility of antibacterial susceptibility testing. After >30 years of study, in vitro susceptibility can be said to predict the response of bacterial infections with an accuracy that is well summarized as the "90-60 rule": infections due to susceptible isolates respond to therapy approximately 90% of the time, whereas infections due to resistant isolates respond approximately 60% of the time. On the basis of a growing body of knowledge, standardized susceptibility testing for selected organism-drug combinations (most notably, Candida species and the azole antifungal agents) has been shown to have similar predictive utility. Antifungal susceptibility testing is now increasingly and appropriately used as a routine adjunct to the treatment of fungal infections.

Multicenter Brazilian study of oral Candida species isolated from AIDS patients

Oropharyngeal candidiasis continues to be considered the most common opportunistic disease in Aids patients. This study was designed to investigate species distribution, serotype and antifungal susceptibility profile among Candida spp. isolated from the oral cavity of Aids patients recruited from six Brazilian university centers. Oral swabs from 130 Aids patients were plated onto CHROMagar Candida medium and 142 isolates were recovered. Yeast isolates were identified by classical methods and serotyped using the Candida Check or target system-Iatron. Antifungal susceptibility testing was performed according to the NCCLS microbroth assay. C. albicans was the most frequently isolated species (91%), and 70% of the isolates belonged to serotype A. We detected 12 episodes of co-infection (9%), including co-infection with both serotypes of C. albicans. Non-albicans species were isolated from 12 episodes, 50% of them exhibited DDS or resistance to azoles. Otherwise, only 8 out 130 isolates of C. albicans exhibited DDS or resistance to azoles. Brazilian Aids patients are infected mainly by C. albicans serotype A, most of them susceptible to all antifungal drugs.

Resistance of Candida species to antifungal agents: molecular mechanisms and clinical consequences

Candida albicans and related species pathogenic for man become resistant to antifungal agents, in particular triazole compounds, by expression of efflux pumps that reduce drug accumulation, alteration of the structure or concentration of antifungal target proteins, and alteration of membrane sterol composition. The clinical consequences of antifungal resistance can be seen in treatment failures in patients and in changes in the prevalences of Candida species causing disease. These effects were seen unequivocally in HIV-infected patients with oropharyngeal candida infections, but their incidence has decreased dramatically with the introduction of highly active antiretroviral therapy. The evidence for similar emergence of antifungal-resistant yeast strains and species in other types of candida infections is confounded by non-standardised susceptibility testing methods and definitions of a resistant fungal isolate. Recent large-scale surveys of yeasts isolated from blood cultures, based on standardised methodology and resistance definitions, do not support the view that antifungal resistance in pathogenic yeasts constitutes a significant or growing therapeutic problem.

Antifungal susceptibility testing: practical aspects and current challenges

Development of standardized antifungal susceptibility testing methods has been the focus of intensive research for the last 15 years. Reference methods for yeasts (NCCLS M27-A) and molds (M38-P) are now available. The development of these methods provides researchers not only with standardized methods for testing but also with an understanding of the variables that affect interlaboratory reproducibility. With this knowledge, we have now moved into the phase of (i) demonstrating the clinical value (or lack thereof) of standardized methods, (ii) developing modifications to these reference methods that address specific problems, and (iii) developing reliable commercial test kits. Clinically relevant testing is now available for selected fungi and drugs: Candida spp. against fluconazole, itraconazole, flucytosine, and (perhaps) amphotericin B; Cryptococcus neoformans against (perhaps) fluconazole and amphotericin B; and Aspergillus spp. against (perhaps) itraconazole. Expanding the range of useful testing procedures is the current focus of research in this area.

Multicenter prospective surveillance of oral Candida dubliniensis among adult Brazilian human immunodeficiency virus-positive and AIDS patients

The incidence of C. dubliniensis in South America has not yet been determined. In the present study, oral swab samples were taken from 108 HIV-infected/AIDS individuals attending 6 separate Brazilian HIV-treatment centers to determine the incidence of C. dubliniensis in this population. Swabs were plated onto CHROMagar Candida medium and 155 isolates, presumptively identified as C. albicans or C. dubliniensis were further investigated. In a preliminary screen for C. dubliniensis, 13 of the 155 isolates showed no or poor growth at 42 degrees C, and all them were subjected to randomly amplified polymorphic DNA (RAPD) and polymerase chain reaction (PCR) analysis using C. dubliniensis-specific primers. We confirmed that 4 out of 13 isolates were C. dubliniensis, representing an incidence rate of 2.8% for the Brazilian HIV-infected population infected with yeasts exhibiting green colonies on CHROMagar Candida. This value is significantly lower than those reported in Ireland and the United States.