Terezinha I.E. Svidzinski

Can intrauterine contraceptive devices be a Candida albicans reservoir

BACKGROUND The in vitro adherence of Candida albicans isolated from vaginal exudates of patients with vulvovaginal candidiasis (VVC) to intrauterine contraceptive devices (IUDs) and biofilm formation capacity were evaluated. STUDY DESIGN This research was conducted with two vaginal C. albicans isolates. The adherence on IUD by both radiomarked adhesion assay and scanning electron microscopy, and the biofilm production capacity by spectrophotometric method were determined. RESULTS The yeasts adhered strongly to different parts of the IUD (covered with copper wire, without copper wire and tail), and there was no significant difference in the rates of adhesion to the different parts (p=.7771). The vaginal yeasts showed a high capacity to produce biofilm. CONCLUSIONS Two vaginal yeasts evaluated showed a high capacity to produce biofilm on IUD. It was confirmed that all parts of the IUD allow the adherence of yeasts. The adherence of C. albicans to different parts of the IUD and its formation of biofilm seems to be important attributes influencing the occurrence of VVC and recurrent VVC.

Analysis of the in vitro adherence of Streptococcus mutans and Candida albicans

The objective of the present study was to investigate the in vitro adherence capacity of Streptococcus mutans and Candida albicans. Adherence assays were conducted on dental surfaces and analyzed by scanning electron microscopy (SEM). Extracted human teeth were inoculated with Streptococcus mutans or Candida albicans and with both species simultaneously, and incubated at 37oC for 21 days. Bacterial inocula had been obtained from saliva samples of children that had been colonized by both organisms. ATCC reference strains were used as controls. SEM analyses showed that the biofilm that covered the entire analyzed dental surface was more homogeneous inoculated with the two microorganisms simultaneously than with each species separately. In a second experiment, carried out with isolates that had shown the highest adherence the isolates were tested for adherence to high-density polyethylene substrates. The potentialization of the adherence capacity of Streptococcus mutans and Candida albicans when in association was confirmed.

Early State Research on Antifungal Natural Products

Nosocomial infections caused by fungi have increased greatly in recent years, mainly due to the rising number of immunocompromised patients. However, the available antifungal therapeutic arsenal is limited, and the development of new drugs has been slow. Therefore, the search for alternative drugs with low resistance rates and fewer side effects remains a major challenge. Plants produce a variety of medicinal components that can inhibit pathogen growth. Studies of plant species have been conducted to evaluate the characteristics of natural drug products, including their sustainability, affordability, and antimicrobial activity. A considerable number of studies of medicinal plants and alternative compounds, such as secondary metabolites, phenolic compounds, essential oils and extracts, have been performed. Thus, this review discusses the history of the antifungal arsenal, surveys natural products with potential antifungal activity, discusses strategies to develop derivatives of natural products, and presents perspectives on the development of novel antifungal drug candidates.

Assessment of in vitro biofilm formation by Candida species isolates from vulvovaginal candidiasis and ultrastructural characteristics

Vulvovaginal candidiasis (VVC) is a very common cause of fungal infection that remains a significant problem worldwide, especially concerning its complex pathogenicity. Biofilm dynamics from vaginal isolates requires further investigation. Different assays, such as cell surface hydrophobicity (CSH), biofilm production, fungal metabolism by 2H-tetrazolium-5-carboxanilide (XTT) and phenazine methosulfate (PMS), scanning electron microscopy (SEM) and confocal scanning laser microscopy (CSLM) were used in order to determine the ability of five Candida species isolates from VVC patients to form in vitro biofilms and their ultrastructural characteristics. All yeasts demonstrated the ability to produce biofilm and showed viability up to 48 h after the completion of assay, confirmed by SEM and CSLM, but differences were observed between them. SEM and CSLM also revealed that all VVC isolates adhered only in blastoconidia form, except for Candida parapsilosis. Even though, only one isolate from each Candida species has been used, the results of high biofilm formation, metabolic activity and CSH showed by Candida albicans and C. parapsilosis, as well as by the ultrastructural characteristics, suggest that these species exhibit greater ability of adherence in relation to the others. Ours results support the theory that virulence potential is multifactorial and that other factors not evaluated in this study could be involved in the CVV physiopathogeny.

Correlation between Etest®, disk diffusion, and microdilution methods for antifungal susceptibility testing of Candida species from infection and colonization.

The correlation between the microdilution (MD), Etest® (ET), and disk diffusion (DD) methods was determined for amphotericin B, itraconazole and fluconazole. The minimal inhibitory concentration (MIC) of those antifungal agents was established for a total of 70 Candida spp. isolates from colonization and infection. The species distribution was: Candida albicans (n=27), C. tropicalis (n=17), C. glabrata (n=16), C. parapsilosis (n=8), and C. lusitaniae (n=2). Non‐Candida albicans Candida species showed higher MICs for the three antifungal agents when compared with C. albicans isolates. The overall concordance (based on the MIC value obtainedwithin two dilutions) between the ET and the MD method was 83% for amphotericin B, 63% for itraconazole, and 64% for fluconazole. Considering the breakpoint, the agreement between the DD and MD methods was 71% for itraconazole and 67% for fluconazole. The DD zone diameters are highly reproducible and correlate well with the MD method, making agar‐based methods a viable alternative to MD for susceptibility testing. However, data on agar‐based tests for itraconazole and amphotericin B are yet scarce. Thus, further research must still be carried out to ensure the standardization to other antifungal agents. J. Clin. Lab. Anal. 23:324–330, 2009.

A Challenge for Clinical Laboratories: Detection of Antifungal Resistance in Candida Species Causing Vulvovaginal Candidiasis

Background: To determine the in vitro susceptibility of vaginal yeasts against 7 antifungals by using 2 different methods and to evaluate if there is a possibility to use diskdiffusion (DD) method in the daily routine. Methods: Eighty-eight vaginal yeasts were tested against 5 antifungal azoles and 2 polyenes, according to Clinical and Laboratory Standards Institute (CLSI) documents DD (M44-A) and broth microdilution (MD) (M27-A3). Results: Resistance was recorded for ketoconazole (KETO), itraconazole (ITR), micoconazole amphotericin B (AMB), and nystatin (NYS). Between DD and MD, higher rates of agreement were observed for AmB (98.9%), voriconazole (VOR) (84.1%), and NYS (77.3%). For the other antifungals, the agreement varied from 34.1% (KETO) to 71.0% fluconazole (FLU). Conclusion: While the DD method may be a useful tool to determine the antifungal susceptibility profile in clinical laboratories in the future, it still requires improvements in its standardization since it was not reliable in detecting resistance in vitro.

Colonization of the oral cavity by yeasts in patients with chronic renal failure undergoing hemodialysis

OBJECTIVES To determine the frequency of yeast in the oral cavity of patients with chronic renal failure, undergoing hemodialysis (PCRFH); identification and antifungal susceptibility profile of yeast and demographic profile of patients. METHODS We performed mouthwash in 146 PCRFH; the rinse fluid was collected and cultured, yeasts grown were identified by phenotypic and molecular methods. The antifungal susceptibility profile was determined against nystatin, amphotericin B, fluconazole, voriconazole, and caspofungin based in Clinical and Laboratory Standards Institute (document M27-A3). RESULTS Positive culture was observed in 39% of patients, of whom 53% were women; the median of dialysis time was 2.9 years. The age of the colonized patients varied between 26 and 84 years, with a median of 52.5 years. PCRFH over 45 years were significantly more colonized (P = 0.0108) as well as denture wearers (84.0%). We isolated 81 yeasts, predominantly Candida albicans (63%) followed by Candida glabrata. In general, yeasts were sensitive to the evaluated antifungal agents, but there was significant variation in the minimum inhibitory concentration, especially among non-C. albicans Candida (NCAC) compared to fluconazole, caspofungin, and amphotericin B. NCAC required significantly higher concentrations of fluconazole (P < 0.01). CONCLUSION The rate of colonization by yeasts in PCRFH was high, and there was variability in species distribution and antifungal susceptibility profile. These results are little known in this group of patients and are important for controlling the risk of developing invasive fungal infections.

Can Lactobacillus acidophilus influence the adhesion capacity of Candida albicans on the combined contraceptive vaginal ring

BACKGROUND This study was conducted to evaluate the influence of Lactobacillus acidophilus on the adhesion capacity of Candida albicans on the combined contraceptive vaginal ring (CCVR). STUDY DESIGN Two vaginal isolates of C. albicans and an ATCC strain of lactobacilli were used. Isolated and associated yeasts and bacteria (co-aggregated) were employed on the CCVR adherence assays and scanning electron microscopy (SEM). RESULTS Isolated yeasts and lactobacilli adhered strongly to the CCVR. After the co-aggregation, there were an increase in adhesion capacity of the yeasts (p<.001) and a diminished adhesion of the lactobacilli (p<.001). SEM showed the isolated and co-aggregated microorganisms intimately attached to the irregularities of the CCVR. CONCLUSIONS If these findings correlated with the conditions in vivo, the use of probiotics based on L. acidophilus or its presence in the vaginal microbiota would not protect against the adhesion of C. albicans to the ring.

Effect of experimental diabetes on the development and maintenance of vulvovaginal candidiasis in female rats.

OBJECTIVE The purpose of this study was to develop an experimental model of diabetes in female rats and verify its influence on vulvovaginal candidiasis. STUDY DESIGN The animals were divided into control and diabetic groups. Diabetes was induced with the use of an intravenous solution of alloxan (42 mg/kg bodyweight). One week after confirmation of hyperglycemia, the inoculation of Candida albicans yeast, previously standardized from a vaginal isolate, in concentrations of about 5 x 10(8), was performed. Infection control was made through vaginal culture, Papanicolaou cytology, and scanning electron microscopy (SCEM). RESULTS The results pointed to different glycemias between the control (74.8 +/- 2.6) and experimental groups (543.1 +/- 12.1) and a significant bodyweight decrease (227.6 +/- 4.77 and 204 +/- 6.39, respectively). The positive infection was shown by culture, Papanicolaou test, and SCEM in the experimental group. CONCLUSION Diabetes mellitus causes hyperglycemia, which was favorable to the vaginal colonization and infection by C albicans.

Oral lesions and colonization by yeasts in hemodialysis patients

BACKGROUND Patients with chronic kidney disease, stage 5, undergoing hemodialysis treatment are frequently colonized by yeasts, with high chance of developing fungal infections. The objective of this study was to assess the presence of yeasts in the oral cavity of these individuals, associating findings with the presence of oral lesions and the use of dental prostheses. METHODS Clinical examinations of the oral mucosa were performed in 52 patients, when the use of removable dental prostheses and the presence of oral lesions were observed and recorded. Saliva samples were collected to identify yeast specimens and colony-forming units. RESULTS Colonization by yeasts was found in 42.31% of the patients, 100% of which belonging to the genus Candida, with the predominance of C. albicans (69.23%). Half of the patients (26) presented some type of oral lesion, the majority (63.33%) suggestive of candidiasis, which was confirmed in 57.89% of cases. The chance that these patients carried yeast colonies in the presence of dental prostheses and oral lesions was 6.33 and 2.62 times higher, respectively. CONCLUSIONS Patients investigated in this study presented a high incidence of yeasts in the oral cavity, with those with oral lesions and dental prostheses being more likely to carry yeasts. When oral lesions are detected in patients undergoing hemodialysis treatment, particularly in those who are prosthesis users, early diagnosis and treatment of this type of lesion, in association with systemic investigations, should be performed to mitigate possible unfavorable prognoses.