Hyphal wall protein 1 gene: A potential marker for the identification of different Candida species and phylogenetic analysis

Candida Infections: The Role of Saliva in Oral Health-A Narrative Review

Candida species, particularly Candida albicans, are causative agents of oral infections to which immunocompromised patients are especially susceptible. Reduced saliva flow (xerostomia) can lead to Candida overgrowth, as saliva contains antibacterial components such as histatins and β-defensins that inhibit fungal growth and adhesion to the oral mucosa. Candida adheres to host tissues, forms biofilms, and secretes enzymes required for tissue invasion and immune evasion. Secretory asparaginyl proteinases (Saps) and candidalysin, a cytolytic peptide toxin, are vital to Candida virulence, and agglutinin-like sequence (Als) proteins are crucial for adhesion, invasion, and biofilm formation. C. albicans is a risk factor for dental caries and may increase periodontal disease virulence when it coexists with Porphyromonas gingivalis. Candida infections have been suggested to heighten the risk of oral cancer based on a relationship between Candida species and oral squamous cell carcinoma (OSCC) or oral potentially malignant disorder (OPMD). Meanwhile, β-glucan in the Candida cell wall has antitumor effects. In addition, Candida biofilms protect viruses such as herpesviruses and coxsackieviruses. Understanding the intricate interactions between Candida species, host immune responses, and coexisting microbial communities is essential for developing preventive and therapeutic strategies against oral Candida infections, particularly in immunocompromised individuals.

The anti-fungal effect of miconazole and miconazole-loaded chitosan nanoparticles gels in diabetic patients with Oral candidiasis-randomized control clinical trial and microbiological analysis

BACKGROUND

Oral thrush is the most common occurring fungal infection in the oral cavity in uncontrolled diabetic patients, it is treated by various antifungal drugs according to each case. This study aimed to evaluate the therapeutic effects of topical application of miconazole and miconazole-loaded chitosan nanoparticles in treatment of diabetic patients with oral candidiasis.

METHODS

In this randomized controlled clinical trial. A total of 80 diabetic patients presenting with symptomatic oral candidiasis were randomly assigned into two treatment groups: miconazole and miconazole-loaded chitosan nanoparticles. The patients were treated for 28 days, and clinical assessments were conducted at baseline, 7, 14, 21 and 28 days. Clinical parameters, including signs and symptoms of oral candidiasis were evaluated and microbiological analysis was performed to determine the Candida species and assess their susceptibility to the antifungal agents. Statistical analysis was done to the categorical and numerical data using chi-square test and Kruskal Wallis test.

RESULTS

The antifungal efficacy between the miconazole and miconazole-loaded chitosan nanoparticles (CS-MCZ) groups insignificant difference (P >  0.05) was observed. Both treatment modalities exhibited comparable effectiveness in controlling oral candidiasis symptoms and reducing Candida colonization as miconazole-loaded chitosan nanoparticles group showed a significant difference in the clinical improvement in respect of both signs and symptoms from baseline (70%) until the end of study at 28 days (5%) (P <  0.05) Moreover, miconazole-loaded chitosan nanoparticles, there was a significant reduction in the number of colonies forming units of Candida albicans from baseline until the end of the study at 28-day with P value <  0.000.

CONCLUSIONS

This randomized controlled clinical trial and microbiological analysis demonstrate that both miconazole and miconazole-loaded chitosan nanoparticles are effective in the treatment of oral candidiasis in diabetic patients with no adverse reactions.

TRIAL REGISTRATION

NCT06072716 with first registration first registration in 10/10/2023.

A well child with prolonged oral thrush: an unexpected diagnostic journey

Oral thrush is a familiar presentation in both general practice and paediatrics, and is usually responsive to treatment in the community. Here, we present the diagnostic journey of a previously well boy aged 3 years who presented with treatment-resistant thrush and describe how 'unexpected' results led to eventual diagnosis and management. This intriguing case was managed jointly by district hospital general paediatric team and tertiary hospital specialist teams.

Clinic-mycological spectrum of Candida infection in diabetic foot ulcers in a tertiary care hospital

Background and Purpose

In diabetic foot ulcers, if fungal agents, such as Candida species penetrate the cutaneous or depth of the ulcer, it can increase the wound severity and make it more difficult to heal.

Materials and Methods

A cross-sectional study was performed on 100 diabetic patients with a foot ulcer from December 2019 to November 2020 in northern Iran. Patient data and wound grades were recorded in a questionnaire. Candida infection was confirmed by direct microscopic examination and culture. To identify the causative agent, polymerase chain reaction-restriction fragment length polymorphism using MspI enzyme and the partial amplification of hyphal wall proteins (HWP1) gene were performed.

Results

Mean age of the participants was 62.1 ± 10.8 years old, and 95% of them had type 2 diabetes. Moreover, more than 83% of them had diabetes for a duration of 10 years. In addition, 59% of the patients were male, and 66% > of them had poor education levels. Besides, 99% of them were married, and 52% were rural. Furthermore, 95% of the participants had neuropathic symptoms and 88% used antibiotics. The HbA1C level was > 9% in 69% of them, and the mean ulcer grade of the patients was 2.6±1.05. Candida infection was detected in 13% of the deep tissue and 7% of the tissue surrounding the wound. The predominant Candida isolate was C. parapsilosis (71.5%) and C. albicans (14.3%). Infections caused by filamentous fungi were not detected. There was a statistically significant relationship between Candida infection and gender, rural lifestyle, HbA1C, and ulcer grade.

Conclusion

Mycological evaluations of diabetic foot ulcers are often ignored. The present study revealed that C. parapsilosis is the most common causative agent of deep-seated foot ulcer infection in these patients and may require specific treatment. Therefore, more attention of physicians to Candida infections, early diagnosis, and prompt treatment can help accelerate wound healing and prevent amputation.

Correlation Between Drug Resistance and Virulence of Candida Isolates from Patients with Candidiasis

Purpose

This article aims to provide a theoretical basis for new or adjuvant strategies to facilitate the early diagnosis and treatment of candidiasis and to determine if drug-resistant Candida would affect virulence.

Patients and Methods

Our strains were collected from patients diagnosed with candidiasis in our hospital. The strains were identified by MALDI-TOF system and ITS sequencing. Antifungal sensitivity testing in vitro was performed to evaluate susceptibility of these isolates to current widely used antifungal drugs. The Galleria mellonella larvae model infected by Candida spp. was used to compare the virulence of drug-resistant and susceptible Candida spp.

Results

A total of 206 Candida strains were collected from clinical specimens. Candida albicans was the most common species among them, and was predominantly isolated from male patients aged over 40 years in ICU environments suffering from pulmonary and/or cerebral conditions. The accuracy rate of MALDI TOF-MS identification was 92.72% when compared with ITS sequencing as the standard method. Most Candida species, except for C. tropicalis which showed high resistance to micafungin, showed high susceptibilities to voriconazole, itraconazole, amphotericin B and micafungin but were highly resistant to terbinafine. For each specific Candida species, the G. mellonella larvae model revealed that the virulence of drug-resistant Candida isolates did not markedly differ from that of the drug-susceptible isolates, however, the virulence was dose-dependent on inoculated fungal cells in this model.

Conclusion

The possibility of Candida infection should not be neglected in patients at critical care hospital settings and C. albicans is the most common causative agent. MALDI-TOF MS has the advantages of rapidity and high accuracy, and should be a preferred method for identification of Candida spp. in a clinical laboratory. Voriconazole, itraconazole, amphotericin B and micafungin can still be recommended as the first line antifungals to treat candidiasis.

Isolation, Characterization, and Antifungal Sensitivity Pattern of Fungal Species with Potential Resistance to Antifungal Drugs in Patients with Otomycosis

Background: Otomycosis is defined as a superficial fungal infection, accounting for about 10% of infectious otitis externa cases. Objectives: This study investigated patients with suspicious symptoms through the examination of their demographic information, isolate etiological agents, and in vitro antifungal susceptibility patterns. Methods: The samples of 170 patients with otitis externa symptoms were collected and confirmed for otomycosis by mycological examination (e.g., potassium hydroxide, methylene blue staining, and fungal culture) and molecular sequencing. In vitro antifungal susceptibility tests against miconazole, fluconazole, itraconazole, voriconazole, posaconazole, amphotericin B, and caspofungin were performed according to the Clinical and Laboratory Standards Institute (M27-A3/S4 and M38-A2). Results: Out of 170 patients, 145 subjects (85.29%) showed positive mycological findings. In this study, 55.8% of the patients were male, and the most common age group affected was 50 - 59 years (26.2%). Hearing loss and pruritus were the most common clinical manifestations. The most common occupation was being a housewife (47.5%), and most cases occurred during the winter (40%). Aspergillus niger was the most common species, followed by Aspergillus fumigatus, Candida albicans, and Candida glabrata. Caspofungin showed the highest activity against Aspergillus and Candida isolates; nevertheless, itraconazole demonstrated the lowest activity against Aspergillus isolates. Fluconazole showed the weakest power against Candida species. Conclusions: Due to climatic conditions, humidity, and dust, otomycosis has a high occurrence in Iran. Although otomycosis needs long-term antifungal therapy and recurrence is high in some cases, it is rarely life-threatening, and eardrop antifungals are usually enough to eradicate the infection. Local information about the antifungal pattern is useful for the control, prevention, and treatment of otomycosis.

Inhibitory effect of 405-nm blue LED light on the growth of Candida albicans and Streptococcus mutans dual-species biofilms on denture base resin

We investigated whether irradiation with 405-nm blue LED light could inhibit the growth of not only single- but dual-species biofilms formed by Candida albicans and Streptococcus mutans on denture base resin and cause the alteration in gene expression related to adhesion and biofilm formation. C. albicans and S. mutans single-/dual-species biofilms were formed on the denture base specimens. The biofilms were irradiated with 405-nm blue LED light (power density output: 280 mW/cm²) for 0 (control) and 40 min. Dual-species biofilms were analyzed using CFU assay and fluorescence microscopy, and single-/dual-species biofilms were analyzed using alamarBlue assays and gene expression analysis. To assess the inhibitory effect of irradiation on dual-species biofilms, specimens after irradiation were aerobically incubated for 12 h. After incubation, the inhibition of growth was assessed using CFU assays and fluorescence microscopy. Data were analyzed using the Mann-Whitney U or Student's t test (p < 0.05). Irradiation produced a significant inhibitory effect on biofilms. Fluorescence microscopy revealed that almost all C. albicans and S. mutans cells were killed by irradiation, and there was no notable difference in biofilm thickness immediately after irradiation and after irradiation and incubation for 12 h. alamarBlue assays indicated the growth of the biofilms was inhibited for 12-13 h. The expression of genes associated with adhesion and biofilm formation-als1 in C. albicans and ftf, gtfC, and gtfB in S. mutans-significantly reduced by irradiation. Irradiation with 405-nm blue LED light effectively inhibited the growth of C. albicans and S. mutans dual-species biofilms for 12 h.

MOLECULAR DETECTION OF THE TWO VIRULENCE GENES HWP1 AND ALS1 IN CANDIDA SPECIES ISOLATED FROM ONYCHOMYCOSIS

OBJECTIVE

The aim: This article was aimed to assess the prevalence of Candida species causing nail infections and to investigate the most important virulence genes that cause adhesion.

PATIENTS AND METHODS

Materials and methods: Samples were collected from General Hospital and the outpatient's clinics in Thi-Qar Province, southern Iraq, during the period from January 2021 to May 2021. Samples were inoculated on Sabouraud Dextrose Agar plates containing 0.5 mg chloramphenicol, then Petri dishes were incubated at 30°C under aerobic conditions and observed for Candida species growth for 24-72 hrs. All isolates were identified by morphologic and chromatic properties on CHROMagar and by Api Candida.

RESULTS

Results: Twenty five isolates were obtained from hundred samples, which belong to five species of the genus Candida, distributed in percentage 9(36%), 4(16%), 4(16%), 4(16%) and 3(12%) of C. glabrata, C. krusei, C. albicans, C. famata and C. tropicalis consecutively and one isolate was not identified. Monoplex PCR technique was used to detect virulence genes (hwp1 and als1) of Candida species. Four Candida albicans isolates (16%) were carried of both hwp1 and als1 genes.

CONCLUSION

Conclusions: The virulence gene (hwp1) can be relied upon in molecular detection as a special diagnostic tool of Candida albicans species except other types causing Candidal onychomycosis.

Genetic Manipulation as a Tool to Unravel Candida parapsilosis Species Complex Virulence and Drug Resistance: State of the Art

An increase in the rate of isolation of Candida parapsilosis in the past decade, as well as increased identification of azole-resistant strains are concerning, and require better understanding of virulence-like factors and drug-resistant traits of these species. In this regard, the present review “draws a line” on the information acquired, thus far, on virulence determinants and molecular mechanisms of antifungal resistance in these opportunistic pathogens, mainly derived from genetic manipulation studies. This will provide better focus on where we stand in our understanding of the C. parapsilosis species complex–host interaction, and how far we are from defining potential novel targets or therapeutic strategies—key factors to pave the way for a more tailored management of fungal infections caused by these fungal pathogens.

Molecular Identification and Antifungal Susceptibility of Yeasts and Molds Isolated from Patients with Otomycosis

Fungal otitis externa, an infection of the external auditory canal caused by molds and yeasts, accounts for approximately 10-20% of ear canal infections accompanying high recurrence. The purpose of the current study was to assess the pattern of etiological agents of otomycosis and resistance profile as well as the rate of tympanic membrane perforation. A total of 1040 patients with symptoms of fungal otitis externa, in a period of two years, were investigated. The mycological tests revealed the presence of different fungi in 237 ears (22.8%). Fungal otitis was more related to filamentous fungi of the species Aspergillus flavus (54.43%), A. tubingensis (10.97%), and A. niger (8.86%), followed by yeasts, Candida orthopsilosis (7.59%), C. albicans (6.75%), and C. parapsilosis (5.06%). Tympanic membrane perforation rate was found to be 6.75% and was more common with otomycosis caused by A. flavus, A. tubingensis and C. albicans. In antifungal susceptibility tests, all tested drugs showed generally good activity against most isolates of molds and yeasts, while tolnaftate, clotrimazole, nystatin, and terbinafine had lowest effects. We found that among Aspergillus isolates, one A. niger isolate was resistant to voriconazole, and one A. flavus isolate was resistant to amphotericin B. Furthermore, among Candida species, three isolates of C. orthopsilosis showed high MIC values to fluconazole, two C. albicans isolates were considered fluconazole resistant and one isolate of C. parapsilosis was resistant to caspofungin and 3 isolates were resistant to fluconazole. Regarding the existence of the cases with perforated tympanic membrane and emerging species causing fungal otitis in the current report, the importance of the early physical examination, precise molecular identification, and the antifungal susceptibility evaluation is highlighted.

High prevalence of asymptomatic nosocomial candiduria due to Candida glabrata among hospitalized patients with heart failure: a matter of some concern?

Background and Purpose:

Heart failure is a leading cause of hospitalization, and asymptomatic candiduria is common in hospitalized patients with low morbidity. However, in most patients, it is resolved spontaneously on the removal of the catheter. Despite the publication of guidelines, there are still controversies over the diagnosis and management of candiduria. However, in hospitalized patients with heart failure, the decision to treat candiduria is especially important since the nosocomial infections are associated with an increase in morbidity, mortality, length of hospital stay, and healthcare costs. Some species of Candida, such as Candida glabrata, are increasingly resistant to the first-line and second-line antifungal medications. The present study aimed to investigate the incidence of asymptomatic Candida urinary tract infection due to C. glabrata and antifungal susceptibility of Candida isolates in hospitalized patients with heart failure.

Materials and Methods:

In total, 305 hospitalized patients with heart failure were studied to identify asymptomatic nosocomial candiduria during 2016-17 in one private hospital in the north of Iran. The Sabouraud’s dextrose agar culture plates with a colony count of >10⁴ colony-forming unit/ml of urine sample were considered as Candida urinary tract infection. Candida species were identified based on the morphology of CHROMagar Candida (manufactured by CHROMagar, France) and PCR-RFLP method with MspI restriction enzyme. Antifungal susceptibility testing of the isolates was performed using five mediations, including itraconazole, voriconazole, fluconazole, amphotericin B, and caspofungin by broth microdilution method according to CLSI M27-S4.

Results:

In this study, the rate of asymptomatic Candida urinary tract infection was 18.8%, which was more common in people above 51 years old and females (70%). In addition to the urinary and intravascular catheter, the occurrence of candiduria in hospitalized patients had significant relationships with a history of surgical intervention, diastolic heart failure, and use of systemic antibiotics (P>0.05). Among Candida spp., non-albicans Candida species was the most common infectious agent (59.7%). Moreover, C. glabrata (n=27, 40.3%) (alone or with other species) and Candida albicans (n=27, 40.3%) were the most common agents isolated in Candida urinary tract infection. Based on the results of the in vitro susceptibility test, the C. glabrata isolates were 15%, 59%, 70%, 74%, and 85% susceptible to caspofungin, amphotericin B, itraconazole, voriconazole, and fluconazole, respectively.

Conclusion:

According to the findings, there was a high prevalence of asymptomatic Candida urinary tract infection in hospitalized patients with heart failure. Besides, it was suggested that there was a shift towards non-albicans Candida, especially C. glabrata, in these patients. Therefore, asymptomatic candiduria in hospitalized patients with heart failure should be considered significant. Furthermore, the identification of Candida species along with antifungal susceptibility is essential and helps the clinicians to select the appropriate antifungal agent for better management of such cases.

Species distribution and susceptibility profiles of Candida species isolated from vulvovaginal candidiasis, emergence of C. lusitaniae

Background and Purpose:

The aim of the current study was to investigate the epidemiology of vulvovaginal candidiasis (VVC) and recurrent VVC (RVVC), as well as the antifungal susceptibility patterns of Candida species isolates.

Materials and Methods:

A cross-sectional study was carried out on 260 women suspected of VVC from February 2017 to January 2018. In order to identify Candida species isolated from the genital tracts, the isolates were subjected to polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) using enzymes Msp I and sequencing. Moreover, antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute guidelines (M27-A3).

Results:

Out of 250 subjects, 75 (28.8%) patients were affected by VVC, out of whom 15 (20%) cases had RVVC. Among the Candida species, C. albicans was the most common species (42/95; 44.21%), followed by C. lusitaniae (18/95; 18.95%), C. parapsilosis (13/95; 13.69%), C. glabrata (8/95; 8.42%), C. kefyr (6/95; 6.31%), C. famata (5/95; 5.26%), C. africana (2/95; 2.11%), and C. orthopsilosis (1/95; 1.05%), respectively. Multiple Candida species were observed in 28% (21/75) of the patients. Nystatin showed the narrowest range of minimum inhibitory concentration (MIC) (0.25-16 μg/ml) against all Candida strains, whereas fluconazole (0.063-64 μg/ml) demonstrated the widest MIC range. In the current study, C. lusitaniae, as the second most common causative agent of VVC, was susceptible to all antifungal agents. Furthermore, 61.1% of C. lusitaniae isolates were inhibited at a concentration of ≤ 2 μg/ml, while 38.9% (n=7) of them exhibited fluconazole MICs above the epidemiologic cutoff values (ECV). Candida species showed the highest overall resistance against fluconazole (61.3%), followed by itraconazole (45.2%) and caspofungin (23.7%). All of C. albicans strains were resistant to itraconazole with a MIC value of ≥ 1 μg/ml; in addition, 87.5% of them were resistant to fluconazole. Moreover, 100% and 87.5% of C. glabrata strains were resistant to caspofungin and fluconazole, respectively.

Conclusion:

As the findings revealed, the majority of VVC cases were caused by non-albicans Candida species which were often more resistant to antifungal agents. Candida lusitaniae generally had fluconazole MICs above the ECV. Given the propensity of C. lusitaniae to develop resistance under drug pressure, antifungals should be administered with caution. The emergence of these species justify the epidemiological surveillance surveys to watch out the distribution of yeast species.

Candida parapsilosis: from Genes to the Bedside

Patients with suppressed immunity are at the highest risk for hospital-acquired infections. Among these, invasive candidiasis is the most prevalent systemic fungal nosocomial infection. Over recent decades, the combined prevalence of non-albicans Candida species outranked Candida albicans infections in several geographical regions worldwide, highlighting the need to understand their pathobiology in order to develop effective treatment and to prevent future outbreaks. Candida parapsilosis is the second or third most frequently isolated Candida species from patients. Besides being highly prevalent, its biology differs markedly from that of C. albicans, which may be associated with C. parapsilosis' increased incidence. Differences in virulence, regulatory and antifungal drug resistance mechanisms, and the patient groups at risk indicate that conclusions drawn from C. albicans pathobiology cannot be simply extrapolated to C. parapsilosis Such species-specific characteristics may also influence their recognition and elimination by the host and the efficacy of antifungal drugs. Due to the availability of high-throughput, state-of-the-art experimental tools and molecular genetic methods adapted to C. parapsilosis, genome and transcriptome studies are now available that greatly contribute to our understanding of what makes this species a threat. In this review, we summarize 10 years of findings on C. parapsilosis pathogenesis, including the species' genetic properties, transcriptome studies, host responses, and molecular mechanisms of virulence. Antifungal susceptibility studies and clinician perspectives are discussed. We also present regional incidence reports in order to provide an updated worldwide epidemiology summary.

Characterization of beta-tubulin DNA sequences within Candida parapsilosis complex

Background and Purpose:

Candida parapsilosis is a common cause of candidemia in children and patients with onco-hematological diseases, septic arthritis, peritonitis, vaginitis, and nail and skin infections. Regarding this, the present study was condcuted to evaluate intra- and inter-species variation within beta-tubulin DNA sequence of C. parapsilosis complex in order to establish the utilization of this gene in the identification and phylogenetic analysis of the species.

Materials and Methods:

A total of 23 isolates representing three different species of C. parapsilosis complex were used in this study, all of which were identifed by ITS-sequencing. For the successful amplification of beta-tubulin gene, a newly designed set of pan-Candida primers was used, followed by bilaterally sequence analysis for pairwise comparisons, determination of multiple alignments, evaluation of sequence identity levels, counting sequence difference, and construction of phylogenetic tree.

Results:

The multiple alignment of 623-629 bp-long nucleotide (nt) sequences reflecting the beta-tubulin gene indicated an inter-species divergence ranging within 0-68 nt in C. parapsilosis, C. orthopsilosis, and C. metapsilosis with a mean similarity of 84.7% among the species. Meanwhile, the intra-species differences of 0-20 and 0-6 nt were found between the strains of C. parapsilosis and C. orthopsilosis, respectively. The phylogenetic tree topology was characterized by a clade made up by C. parapsilosis and C. orthopsilosis, while C. metapsilosis formed a related but separate lineage.

Conclusion:

Our data provided the basis for further discoveries of the relationship between the species belonging to C. parapsilosis complex. Furthermore, the findigns of the prsent study revealed the efficiency of beta-tubulin DNA sequence data in the identification and taxonomy of C. parapsilosis and other pathogenic yeasts.