Identification of Candida spp. by phenotypic tests and PCR

Vulvovaginal candidiasis, an increasing burden to women in the tropical regions attending Bharatpur Hospital, Chitwan

Vulvovaginal candidiasis is a yeast infection commonly caused by the overgrowth of Candida species in and around the vulva and vagina. Abnormal vaginal discharge, itching and irritation, swelling and redness of the vaginal area, pain during sexual intercourse, and dyspareunia are important clinical findings of the infection. Currently, the infection is one of the growing burdens to married women. Moreover, the infection with antifungal-resistant Candida species adds challenges to managing the disease. Hence, this study was conducted to identify the different Candida species causing vulvovaginal candidiasis and to determine its susceptibility pattern against different antifungal drugs. A hospital-based cross-sectional and quantitative study was conducted for the period of six months from September 2022 to March 2023 among symptomatic married women in the Gynecology and Obstetrics Department of Bharatpur Hospital, Chitwan. A total of 300 symptomatic cases were enrolled in the study. Candida species were isolated from vaginal swabs following standard microbiological procedures and antifungal susceptibility testing was performed with different antifungal agents. The total prevalence of vulvovaginal candidiasis was found to be 37.3 % (112/300). Among different isolates, Candida albicans was found to be the most predominant (52.6 %), followed by Candida glabrata (29.3 %) among non-albicans. Women from the age group 25-35 years were found to be more infected (47.3 %) and the relationship between contraceptive use and vulvovaginal candidiasis was found to be statistically significant (p < 0.05). Candida species showed higher susceptibility toward Amphotericin-B (68.1 %), followed by fluconazole (Diflucan), and Clotrimazole (50.9 %). Whereas the least susceptibility was observed to Voriconazole (27.6 %) and Itraconazole (35.30 %). Candida albicans was comparatively more susceptible to different antifungal drugs than non-albicans species. Candida parapsilosis was only susceptible to Amphotericin-B and the increasing incidence of vaginal candidiasis due to non-albicans Candida indicates the need for routine speciation of Candida.

Isolation and identification of Candida species from catheter-associated urinary tract infection in Thamar city hospitals, Yemen

BACKGROUND

The incidence of urinary tract infections associated with Candida is increasing in Yemeni public hospitals.

OBJECTIVES

The primary objective of this research was to isolate specific Candida species responsible for catheter-associated urinary tract infections (UTIs) and to examine the antifungal sensitivity of these Candida isolates.

PATIENTS AND METHODS

A total of 200 samples were collected from patients with catheters admitted to multiple hospitals of Thamar city (Yemen). There were 50 positive samples with Candida out of 200 samples. We conducted the primary identification process using the established protocols. Before isolation and identification, all yeast isolates underwent sub-culturing on Sabouraud dextrose agar. We employed the standard microbiological procedures such as Gram staining, colonial morphology analysis, lactophenol cotton blue assay, germ tube formation assessment, colony staining on chrom agar Candida medium, and incubation at 37 °C for 48 h. The assessment of cultures was conducted by evaluating their predominant species. All Candida isolates were tested for antifungal susceptibility using the disk diffusion technique, as indicated by the Clinical and Laboratory Standards Institute (CLSI) M44-A document recommendations.

RESULTS

In this study, the prevalence of Candida species obtained from catheter-associated UTIs was shown to be the highest among individuals aged 51-60 years (28.0%) and the lowest was among those aged 10-20 years (8.0%). Males exhibit higher rates than females, with males accounting for 56.0 and females for 44.0%, respectively. The predominant strain from catheters linked to urinary tract infections was Candida albicans. The Candida isolates had the highest susceptibility to itraconazole, with fluconazole and nystatin at sensitivity rates of 64, 60, and 50%, respectively. Amphotericin B and ketoconazole exhibited the most elevated concentrations. The p value of duration of catheterization < 5 was significant (p = 0.01), as well as significant in anti-fungal susceptibility testing of itraconazole, ketoconazole, and nystatin which are (p = 0.03), (p = 0.04), and (p = 0.03) respectively.

CONCLUSION

Urinary tract infection due to candiduria was more common in patients with indwelling urinary catheter. The catheter-associated urinary tract infection caused by Candida species occurred mainly in old male patients. Candia albicans was the predominant Candida species isolated from urinary tract infection associated with urinary catheter at Thamar city hospitals. This study determined that diabetes and antibiotic use are significant predisposing factors associated with isolation of Candida in specimens submitted by patients at Thamar city hospitals.

Anticandidal Efficacy of Oral Probiont Limosilactobacillus fermentum Against Dental Caries Pathogens in Children, Tamil Nadu, India

Dental caries remains a prevalent concern among children globally and is associated with Candida sp. Some researchers have suggested probiotic supplements as a possible solution for reducing dental caries. A study conducted in Tamil Nadu focused on collecting 80 dental caries samples from both males and females, obtained from two different locations. The samples underwent processing using the spread plate technique, followed by anticandidal activity assessments. Through ITS sequence analysis, candida strains were identified, including C. albicans (DDGRPO1, DDGRPO2). The study specifically investigated the ability of the probiotic bacterial strain Lb. fermentum cell-free filtrate to inhibit C. albicans. The research revealed that Lb. fermentum probiotics effectively inhibited the growth of C. albicans DDGRP01, displaying strong antifungal activity against Candida sp. (98%). While these results are promising, it is worth mentioning the increasing interest in exploring innovative alternatives to probiotic-based treatments. This avenue of research offers potential for a more comprehensive approach to addressing this issue. Notably, Lb. fermentum, derived from the human oral cavity, emerges as a significant postbiotic candidate for dental prophylaxis, indicating a hopeful direction for future studies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01175-5.

Anticandidal activity of nanocomposite based on nanochitosan, nanostarch and mycosynthesized copper oxide nanoparticles against multidrug-resistant Candida

Recently, antimicrobial resistance has increased globally particularly Candida infections. Most of antifungal drugs used for treating candidiasis became resistant to most of Candida species. In the current study, a nanocomposite based on mycosynthesized copper oxide nanoparticles (CuONPs), nanostarch, nanochitosan was prepared. Results illustrated that twenty-four Candida isolates were isolated from clinical samples. Furthermore, three Candida strains were selected as the most resistant among others toward commercial antifungal drugs; these selected strains were identified genetically as C. glabrata MTMA 19, C. glabrata MTMA 21 and C. tropicalis MTMA 24. Characterization of the prepared nanocomposite was carried out using physiochemical analysis included Ultraviolet-visible spectroscopy (Uv-Vis), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX) and Transmission Electron Microscopy (TEM). Moreover, the nanocomposite exhibited promising anticandidal activity against C. glabrata MTMA 19, C. glabrata MTMA 21 and C. tropicalis MTMA 24, where the inhibition zones were 15.3, 27 and 28 mm, respectively. Ultrastructure changes observed in nanocomposite-treated C. tropicalis demonstrated disruption of the cell wall which led to cell death. In conclusion, our results confirmed that the novel biosynthesized nanocomposite based on mycosynthesized CuONPs, nanostarch and nanochitosan is a promising anticandidal agent to fight multidrug-resistant Candida.

Isolation and Identification of Candida tropicalis as a Cause of Cutaneous Candidiasis in Kalar District, Iraq

Fungal infections are currently causing health issues all over the world, among which are Candida species that cause cutaneous infection. Numerous dermatological studies concentrated on a single species. However, the virulence factors and the spread of specific candidiasis in specific areas have remained poorly understood. Therefore, the current study was designed to shed light on Candida tropicalis, which has been identified as the most prevalent yeast among Candida non-albicans species. Forty specimens were collected from patients with cutaneous fungal infection (25 females and 15 males) and underwent examination. According to conventional identification based on macroscopic and microscopic examinations, eight isolates were identified as C. tropicalis from Candida non-albicans. Molecular diagnosis for internal transcribed spacers (ITS1 and ITS4) using conventional polymerase chain reaction (PCR) yielded an amplicon of 520 bp for all isolates. Further investigation of PCR-restriction fragment length using Mitochondrial sorting protein; Msp1 enzyme revealed two bands of 340 and 180 bp. The ITS gene sequence in one isolated species was found to be 98% identical to C. tropicalis strain MYA-3404 chromosome R ATCC CP047875.1. Another isolate shared 98.02% identity with C. tropicalis strain MA6 18S ribosomal RNA gene DQ666188.1, indicating C. tropical species identity, implying that non-Candida species should be considered when diagnosing candidiasis. This study demonstrated the significance of Candida non-albicans, particularly C. tropicalis, in terms of pathogenic potential, the ability to cause potentially fatal systemic infections and candidiasis, and acquired flucozonal resistance with a high mortality rate.

Antifungal Susceptibility of Candida albicans Isolated from Tongue and Subgingival Biofilm of Periodontitis Patients

The subgingival biofilm, as the most complex microbial community, has been proven to be reservoir of Candida spp. The main concept of this study was to investigate if there is a difference between the sensitivity of Candida albicans (C. albicans) isolated from tongue and subgingival areas of periodontitis patients to antifungal agents. The aim of the study was to determine: (1) the distribution of different Candida species in the tongue and subgingival samples of periodontitis patients; (2) the susceptibility of Candida albicans strains from tongue and subgingival biofilm to the effects of commonly used antifungal agents: fluconazole, amphotericin B and itraconazole; (3) the correlation between the susceptibility of Candida albicans and clinical periodontal parameters. Tongue and subgingival biofilm samples of periodontitis subjects (N = 163) were examined. Susceptibility was tested when the same Candida species was isolated from both sites (17 subjects). Candida spp. were isolated in 23.3% of tongue and 21.5% of the subgingival samples. All isolates were susceptible to amphotericin B, while 64.71% of tongue and 52.94% of subgingival isolates were susceptible to fluconazole. A low frequency of itraconazole susceptibility was observed for tongue (17.64%) and subgingival isolates (11.76%). The correlations between full-mouth plaque score and Minimal Inhibitory Concentration (MIC) for tongue isolates were strongly positive for all antimycotics. Positive correlation was also observed between moderate periodontal destruction and MICs for tongue and subgingival isolates. The susceptibility of C. albicans to antifungals correlate with oral hygiene and moderate periodontal destruction. There is no difference in antifungal susceptibility between tongue and subgingival isolates.

Impact and fungitoxic spectrum of Trachyspermum ammi against Candida albicans, an opportunistic pathogenic fungus commonly found in human gut that causes Candidiasis infection

BACKGROUND

Trachyspermum ammi (commonly known as Ajwain), a medicinal plant of the Apiaceae family is scientifically acknowledged to harbor potential bioactive compounds for the treatment of gastrointestinal issues, loss of appetite, bronchial difficulties, cough, inflammation, diarrhoea, headache, hypertension, stomach discomfort, bronchitis and influenza. Candida albicans is generally a commensal fungus found in the gastrointestinal and genitourinary systems.

OBJECTIVE

This study was focused on secondary metabolites of T. ammi and its effects towards candidiasis infection as caused by C. albicans.

METHODS

Phytochemical components of T. ammi as a crude extract were extracted through maceration method using three polar (ethanol, methanol and water) and two non-polar (chloroform and diethyl ether) solvents and subjected to 14 phytochemical tests. Further, the crude extract of T. ammi was analyzed over gas chromatography-mass spectroscopy (GC-MS) and Fourier transform infrared spectroscopy (FTIR). Evaluation of antimicrobial property of the extract was carried out by minimum fungal concentration (MFC) and minimal inhibitory concentration (MIC). In addition, cell reduction assay was performed using flowcytometry to confirm the antifungal effect of Ajwain crude extract.

RESULTS

The aqueous extract showed high presence of phytochemicals including alkaloids, carbohydrates, flavonoids, resins, steroids, tannins, inorganic acids, organic acids, phenolic compounds, amino acids, protein and coumarins. GCMS analysis revealed seven bioactive compounds, in which thymol was detected in significant amount in the chromatogram. FTIR performance showed the presence of various stretching vibration including OH, CH, CC, CO, CN and COC. However, the MFC and MIC of Ajwain extracts using different solvent showed that the methanolic extract possesses maximum antifungal efficacy at 250 μg/ml and 15.6 μg/ml, respectively. In addition, cell reduction assay exhibited significant cell reduction in Ajwain methanolic extract compared to the other crude extracts used in the study.

CONCLUSION

Overall, the findings revealed that Ajwain methanolic crude extract has antifungal activity against C. albicans; however, that further needs to be established at molecular level.

Ketorolac-fluconazole: A New Combination Reverting Resistance in Candida albicans from Acute Myeloid Leukemia Patients on Induction Chemotherapy: In vitro Study

BACKGROUND AND OBJECTIVES

Candida albicans is a significant source of morbidity and mortality for patients with acute myeloid leukemia (AML). Prolonged use of fluconazole as empirical antifungal prophylaxis in AML patients leads to overexpression of efflux pump genes that resulted in the emergence of azole-resistant species. Consequently, the introduction of a new strategy to improve the management of C. albicans infections is an urgent need. Nonsteroidal anti-inflammatory drug (NSAID) ketorolac is associated with a reduction in cancer relapses. The present study was performed to investigate the use of ketorolac-fluconazole combination to reverse fluconazole resistance in C. albicans isolated from AML patients on induction chemotherapy.

PATIENTS AND METHODS

One hundred and seventy AML patients were evaluated. Fifty C. albicans were isolated and subjected to disc diffusion assay and broth microdilution for fluconazole alone and combined with different concentrations of ketorolac. Efflux pump gene (CDR1, CDR2, and MDR1) expressions were quantified by real-time PCR.

RESULTS

The tested ketorolac acted synergistically with fluconazole against resistant C. albicans with the minimum inhibitory concentration (MIC) of fluconazole decreased from >160 μg/mL to 0.3-1.25 μg/mL in (93.8%) of resistant isolates with fractional inhibitory concentration index (FICI) value of 0.25. The majority of the resistant isolates overexpressed CDR1 (71.1%) and MDR1 (60%).

CONCLUSION

Ketorolac-fluconazole in vitro combination would be a promising strategy for further clinical in vivo trials to overcome fluconazole resistance in AML patients on induction chemotherapy.

Soil-Associated Bacillus Species: A Reservoir of Bioactive Compounds with Potential Therapeutic Activity against Human Pathogens

Soil hosts myriads of living organisms with the extensive potential to produce bioactive compounds. Bacteria are the major soil inhabitants that represent a rich reservoir for antibiotic production along with their role in recycling nutrients and maintenance of the soil ecosystem. Here, from 55 tested soil samples, we isolated and identified a novel antibiotic-producing bacterial strain with a phylogenetically closest match to Bacillus subtilis sp. based on BLASTN search of GenBank for the 16S rRNA gene sequence. We characterized this novel strain through microscopic, biochemical, and molecular techniques, combined with testing its potential antimicrobial activity. Chemical studies revealed that the antibiotic produced by this strain is a glycopeptide. It exhibited profound activity against both methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans. The antibiotic is optimally produced at 37 °C after 28 h of growth. The biocompatibility of the extracted antibiotic was tested over a wide range of factors including temperature, pH, surfactants, and metal salts. To confirm its therapeutic potential, a sterile solution of the antibiotic was tested in vivo against bacteria-induced keratitis in rats where significant healing activity was recorded. Hence, this soil Bacillus strain may lead to the development of novel antibiotics for the treatment of human pathogens.

Isolation, characterization, and molecular identification of Candida species from urinary tract infections

BACKGROUND AND PURPOSE

Candida species are reportedly the most common human fungal pathogens. The incidence of urinary tract infections (UTIs) caused by Candida pathogens has increased in recent decades. However, such infections rarely occur in the absence of any predisposing factors. Regarding this, the aim of the present study was to identify the Candida species causing UTIs and determine the predisposing factors for candiduria.

MATERIALS AND METHODS

The current study was conducted on 1,450 urine samples obtained from patients suspected of UTI. Out of this number, 19 cases were candidiasis, and 2 cases were mixed infections caused by bacteria and fungi. Candida species were diagnosed differentially using the germ tube test, colony staining on CHROMagar medium, intracellular beta-glucosidase enzyme activity, and glucose absorption pattern. Then, the colonies with the same morphology were confirmed by the DNA sequencing of internal transcribed spacer regions.

RESULTS

According to the results, 38%, 28.6%, 14.3%, and 9.5% of the isolates were identified as C. albicans, C. glabrata, C. tropicalis, and C. kefir/C. krusei, respectively. The presence of one or more predisposing factors was proved in all patients in whom diabetes was the most prevalent predisposing factor (21.1%).

CONCLUSION

Based on the obtained results, C. albicans species was the most prevalent fungal species. In addition, urinary fungal infections were less prevalent than bacterial urinary infections.

Presence of Candida species in the subgingival oral biofilm of patients with peri-implantitis

BACKGROUND

There are no studies that have investigated the presence of Candida species in the subgingival oral biofilm (OB) of patients with peri-implantitis.

PURPOSE

The aim was to assess the presence of Candida species in the subgingival OB of patients with peri-implantitis.

MATERIALS AND METHODS

Individuals with (group A) and without (group B) peri-implantitis were included. Life style related and demographic data were collected using a questionnaire. In both groups, peri-implant plaque-index (PI), bleeding-on-probing (BOP), and probing-depth (PD) were evaluated and crestal bone loss (CBL) were measured on digital bitewing radiographs. In both groups, subgingival OB samples were collected using sterile paper points. Identification of Candida species was performed using ChromAgar medium and colony forming units per milliliter (CFU/mL) were determined. Statistical analysis was performed, and level of significance was set at P < 0.05.

RESULTS

The mean age of individuals in groups A (n = 43) and B (n = 41) were 52.2 ± 4.4 and 55.1 ± 2.3 years, respectively. All participants were male. In groups A and B, implants were in function for 7.4 ± 1.3 and 6.8 ± 0.6 years, respectively. Scores of peri-implant PI (P < 0.001), BOP (P < 0.001), PD (P < 0.001), and CBL (P < 0.001) were significantly higher in group A than group B. Subgingival Candida was isolated from the OB of 33 (76.7%) patients in group A and 5 (12.2%) individuals in group B. The most common yeast species was Candida albicans, which was isolated from 67.4% to 60% individuals in groups A and B, respectively. The number of subgingival oral yeasts CFU/mL were significantly higher in group A (3147.54 ± 1052.6 CFU/mL) compared with group B (496.68 ± 100.2 CFU/mL; P < 0.01).

CONCLUSION

Candida species (predominantly C. albicans) are present in the subgingival OB of patients with peri-implantitis. Community-based efforts toward routine oral hygiene maintenance are needed to improve oral health and minimize the risks of peri-implant diseases in populations.

Subgingival areas as potential reservoirs of different Candida spp in type 2 diabetes patients and healthy subjects

OBJECTIVES

The aim of this cross-sectional observational study was to compare the prevalence of different oral Candida spp. in patients with Type 2 Diabetes and chronic periodontitis in two oral sites: dorsal surface of the tongue and subgingival area. In order to determine subgingival areas as potential reservoirs of yeasts, this study aimed to find differences in the yeasts' detection between the dorsum of the tongue, as the oral site most commonly inhabited with microorganisms, and subgingival samples. Additionally, potential predictors for the yeasts prevalence were determined.

MATERIAL AND METHODS

Subjects (N = 146) were divided into four groups: group A- healthy individuals without periodontitis, group B- healthy individuals with chronic periodontitis, group C- Type 2 Diabetes patients with good glycoregulation and Chronic periodontitis and group D- Type 2 Diabetes patients with poor glycoregulation and Chronic periodontitis. Samples were obtained from the tongue by swabbing. Subgingival plaque samples were taken by paper points and periodontal curette. Isolation and identification of different Candida spp. was done using ChromAgar medium. In addition, germ-tube production and carbohydrate assimilation tests were performed.

RESULTS

The prevalence of Candida spp. was higher in diabetics with poor glycoregulation. The most frequently isolated species was Candida albicans followed by Candida glabrata and Candida tropicalis. In 15.6% of cases, Candida spp. was present in the subgingival area while absent on the tongue. Multivariate regression model showed that HbA1c was Candida spp. predictor for both locations.

CONCLUSIONS

Our results confirmed that there are Candida spp. carriers among subjects with clinically healthy oral mucosa. Also, this study identified subgingival areas as potential reservoirs of these pathogenic species. Glycoregulation has been recognized as a positive predictor factor of Candida spp.

Relationship between Sap prevalence and biofilm formation among resistant clinical isolates of Candida albicans

Background

Fungal infections represent a serious health problem especially in immunocompromised individuals. Candida albicans is the most common fungi that cause superficial and systemic infections with high mortality rates. Anti-fungal resistance of C. albicans may be attributed to its virulence. Biofilm formation and proteolytic activity are major virulence determents that may influence both pathogenicity and anti-fungal resistance of Candida albicans.

Objective

This work studied the relation between biofilm formation, proteolytic activity and prevalence of some Sap genes with reduced susceptibility of C. albicans to different anti-fungal agents.

Methods

Fifty three C. albicans strains isolated from patients with systemic infections, identified by germ tube, chromogenic agar and confirmed by PCR, were subjected to evaluate their proteolytic activity, the degree of biofilm production and the prevalence of Sap9 and Sap10 genes. The susceptibility of the isolates was determined by disk diffusion method against five antifungal drugs.

Results and conclusion

Four of the C. albicans isolates were resistant to 3 anti-fungal drugs, strong biofilm producer, have proteolytic activity and contain either Sap9 or Sap10 or both. Conclusively, although anti-fungal resistance among the isolates was rare, a relation between the anti-fungal resistance and some major virulence factors was evidently proved in this study.

Use of PCR-denaturing gradient gel electrophoresis for the discrimination of Candida species isolated from natural habitats

Candida species are opportunistic microbes that cause chronic infections for a human being. Therefore, the exact identification of Candida species is extremely important for improved therapeutic strategy against these species. Identification based on conventional methods cannot differentiate between some of yeasts species, hence PCR based molecular techniques and sequencing could be an alternative tool for the yeasts identification. A quick molecular method based on the polymerase chain reaction (PCR) and Denaturing Gradient Gel Electrophoresis (DGGE) was applied for distinguishing strains belonging to the Candida species. Six different species designated as AH-20, AH-21, AH-22, AH-23, AH-24 and AH-25 were isolated from soil samples, and their exact identification was detected based on the D1/D2 domain of the 26S rRNA gene amplification and sequence determination. Alignment results and the comparison of 26S rRNA gene sequences of the isolates to 26S rRNA gene sequences available in the GenBank database, as well as the phylogenetic analysis, confirmed the accurate position of the isolates as Candida intermedia strain AH-20, Candida boidinii strain AH-21, Candida tropicalis strain AH-22, Candida mengyuniae strain AH-23, Candida maltosa strain AH-24 and Candida maltosa strain AH-25. Fragments of the D1/D2 domain of 26S rRNA gene were amplified using NL1-GC/LS2 primers and separated by the DGGE. Results showed that all Candida species reported in this study were well discriminated by a distinct band in the DGGE profile. Our results demonstrated that DGGE technique using NL1-GC/LS2 primers could use for the rapid discrimination of yeast strains belonging to the same genera.

Presence of different Candida species at denture wearers with type 2 diabetes and clinically healthy oral mucosa: Pilot study

Background/Aim: The aim of this study was to examine prevalence of different Candida spp. at diabetics and nondiabetics wearing dentures without clinical signs of Denture Stomatitis (DS) and to study if some local and systematic factors are confounders for harboring Candida at these subjects. Material and Methods: Total of 60 subjects wearing partial or complete upper acrylic denture having at least half of palatal mucosa covered by denture were selected and stratified into three experimental groups: systematically health subjects; patients with diagnosed Type 2 Diabetes (T2D) and good glycoregulation; and T2D subjects with poorly regulated blood sugar level. Cotton swab samples were obtained from each patient from hard palate mucosa and denture surface. Swab cultures were made on Sabouraud dextrose agar and ChromAgar Media for distinciton of various Candida spp. Density growth was also measured. Results: Frequency of Candida spp. findings were similar between groups. At healthy subjects, only C.albicans was detected. At diabetics, C.albicans was the most common isolated species, followed by C.glabrata and C.tropicalis. Negative finding of yeasts on palatal mucosa, but positive on denture surface were detected at all groups, with the highest frequency (33.4%) at diabetics with poor glycoregulation. Denture surface was heavier colonized than hard palate mucosa. Duration of diabetes in years were only independent predictors for harboring Candida spp. at denture surface (Exp B=1.186, CI=1.047-1.344, p=0.007). Conclusions: Prosthesis of denture wearers without DS may serve as reservoir of Candida spp. Presence of more pathogenic and resistant non-albicans species are related to diabetics, even without clinical signs of DS.

Evaluating the probiotic and therapeutic potentials of Saccharomyces cerevisiae strain (OBS2) isolated from fermented nectar of toddy palm

The purpose of this study is to evaluate the probiotic characteristics of 15 yeast strains isolated from nectar of toddy palm. Initially, the collected samples were inoculated on yeast extract peptone dextrose agar plates and the colonies so obtained were culturally and morphologically characterized. Commercial probiotic yeast, Saccharomyces boulardii served as the control in these experiments. Of the 15 yeast strains, the isolates that were resistant to antibiotics and worked synergistically with other cultures were considered for further evaluation. Selected isolates were evaluated in vitro for tolerance to simulated gastrointestinal conditions such as temperature, pH, bile and gastric juice. Further the yeast isolates were evaluated for their pathogenicity and adherence to intestinal epithelial cells. The 2 yeast isolates with efficient probiotic properties were finally characterized by sequencing their 5.8 S rRNA and partial sequences of internal transcribed spacer 1 and 2. The sequences were BLAST searched in the National Center for Biotechnology Information, nucleic acid database for sequence similarity of organisms and phylogenetic evolutionary analysis was carried out. Based on maximum similarity of basic local alignment search tool results, organisms were characterized as Pichia kudriavzevii OBS1 (100%) and Saccharomyces cerevisiae OBS2 (96%) and sequences were finally deposited in the GenBank data library. Among these two isolates, S. cerevisiae OBS2 displayed slight/moderate antioxidant and anticancer property. Hence, strain OBS2 can be utilized and explored as a potential probiotic for therapeutic applications.

Phenotypic and genotypic detection of Candida albicans and Candida dubliniensis strains isolated from oral mucosa of AIDS pediatric patients

The aim of this study was to assess a collection of yeasts to verify the presence of Candida dubliniensis among strains isolated from the oral mucosa of AIDS pediatric patients which were initially characterized as Candida albicans by the traditional phenotypic method, as well as to evaluate the main phenotypic methods used in the discrimination between the two species and confirm the identification through genotypic techniques, i.e., DNA sequencing. Twenty-nine samples of C. albicans isolated from this population and kept in a fungi collection were evaluated and re-characterized. In order to differentiate the two species, phenotypic tests (Thermotolerance tests, Chromogenic medium, Staib agar, Tobacco agar, Hypertonic medium) were performed and genotypic techniques using DNA sequencing were employed for confirmation of isolated species. Susceptibility and specificity were calculated for each test. No phenotypic test alone was sufficient to provide definitive identification of C. dubliniensis or C. albicans, as opposed to results of molecular tests. After amplification and sequencing of specific regions of the 29 studied strains, 93.1% of the isolates were identified as C. albicans and 6.9% as C. dubliniensis. The Staib agar assay showed a higher susceptibility (96.3%) in comparison with other phenotypic techniques. Therefore, genotypic methods are indispensable for the conclusive identification and differentiation between these species.

Prevalence of Candida species in the buccal cavity of diabetic and non-diabetic individuals in and around Pondicherry

OBJECTIVES

The aim of the present study was to determine the prevalence of Candida in the buccal cavity of diabetic and non-diabetic individuals in and around Pondicherry, India and to analyse the antifungal susceptibility profile of the selected isolates.

MATERIALS AND METHODS

A total of 400 buccal samples, 200 each from diabetic and non-diabetic healthy individuals were included in the study. Sabouraud's dextrose agar was used for isolation of Candida species. Identification was performed through microscopy, germ tube test, sugar fermentation test, sugar assimilation test and by using Hichrome agar. Distinct and phenotypically representative colonies were selected and subjected to ITS analysis. In vitro antifungal susceptibility testing for the isolated Candida species was performed using E-test.

RESULTS

Results revealed that the prevalence of Candida species in diabetic individuals was higher when compared with non-diabetic healthy individuals. The most predominantly isolated species in diabetic and non-diabetic individuals from buccal cavity was Candida albicans. C. tropicalis was predominant among the non-albicans Candida isolated from both diabetic and non-diabetic individuals. Among denture wearers C. glabrata was predominant. In vitro antifungal susceptibility testing shows that ketoconazole, fluconazole and itraconazole were effective against the isolated Candida species.

CONCLUSIONS

The rate of candidal carriage in diabetic individuals is higher. Different species of Candida are present in the oral cavity of diabetic individuals. There may be a positive correlation between glycemic control and candidal colonization. In vitro antifungal susceptibility testing of Candia species are required for proper management and treatment of candidal infections.

Causative Agents of Onychomycosis: A 7-Year Study

BACKGROUND

Onychomycosis is principally caused by dermatophyte species, but nondermatophyte molds and yeasts have also been involved, causing different clinical manifestations. The aim of this investigation is to determine the clinicomycological and epidemiological profile of the etiologic agents of onychomycosis.

METHODS

The study population included 9,785 suspected cases of onychomycosis referred to the Medical Mycology Reference Laboratory in Isfahan, Iran, during 2007-2014. Nail clipping was collected in sterile Petri dishes for direct microscopic examination and culture. Clinical isolates were identified by using phenotypic tests and molecular techniques.

RESULTS

Of total 9,785 cases with clinical suspicion of onychomycosis comprised in the present study, 1,284 patients (13.1%) were positive by direct microscopy. Age range of patients was between 1 and 82 years. Housewives were the commonest infected population. Candida albicans was the most prevalent species isolated from patients in this study (34.9%) followed by Trichophyton interdigitale (11.7%) and Aspergillus flavus (9.1%).

CONCLUSION

The pattern of causative agents and clinical signs of onychomycosis is altering region to region, so repeated epidemiological surveys of onychomycosis seems to be fundamental. The present study provides novel and appropriate epidemiologic data of onychomycosis for the better prevention and treatment of this fungal infection.

Occurrence of yeasts, pseudomonads and enteric bacteria in the oral cavity of patients undergoing head and neck radiotherapy

The aim of this study was to evaluate the occurrence of yeasts, pseudomonads and enteric bacteria in the oral cavity of patients undergoing radiotherapy (RT) for treatment of head and neck cancer. Fifty patients receiving RT were examined before, during and 30 days after RT. Saliva, mucosa, and biofilm samples were collected and microorganisms were detected by culture and polymerase chain reaction (PCR). The most prevalent yeasts in patients submitted to RT were Candida albicans, C. tropicalis, C. krusei, C. glabrata and C. parapsilosis. Citrobacter, Enterobacter, Enterococcus, Klebsiella, Proteus, and Pseudomonas were the most frequently cultivated bacteria. Before RT, targeted bacteria were cultivated from 22.2% of edentulous patients and 16.6% of dentate patients; 30 days after RT, these microorganisms were recovered from 77.8% edentulous and 46.8% dentate patients. By PCR, these microorganisms were detected from all edentulous patients, 78.1% of dentate patients. The presence of Gram-negative enteric roads and fungi was particularly frequent in patients presenting mucositis level III or IV. Modifications in the oral environment due to RT treatment seem to facilitate the colonization of oral cavity by members of family Enterobacteriaceae, genera Enterococcus and Candida.