Is the prevalence of allergic bronchopulmonary aspergillosis greater in severe asthma?

BACKGROUND: Allergic bronchopulmonary aspergillosis (ABPA) is thought to occur more frequently in severe than in mild asthma. However, there is no precise data to support this hypothesis. OBJECTIVE: To determine the prevalence of ABPA in subjects with varying asthma severity. METHODS: We conducted a secondary analysis of prospectively collected data from 543 adult asthma subjects classified according to the 2004 Global Initiative for Asthma guidelines. The asthma severity was categorized into mild, moderate, and severe. We report the prevalence of ABPA in each asthma category. We also performed multivariable logistic regression analysis to identify factors associated with ABPA in subjects with asthma. RESULTS: We classified 81 (15%), 257 (47%), and 205 (38%) subjects as mild, moderate, and severe asthma. We diagnosed ABPA in 106 (19.5%) subjects. The prevalence of ABPA was 11.1% (9/81) in mild, 21% (54/257) in moderate, and 20.7% (43/205) in severe asthma (p=0.12). Multivariable analysis identified age and asthma duration as significant factors associated with ABPA, whereas asthma severity was not significantly associated. CONCLUSION: The prevalence of ABPA does not vary significantly with the severity of asthma. These findings support the revised International Society of Human and Animal Mycology ABPA working group recommendation for screening all asthma patients for ABPA, irrespective of asthma severity. Further large-scale studies across different geographic regions are warranted to validate these findings.

Population prevalence of aspergillus sensitization and allergic bronchopulmonary aspergillosis in COPD subjects in North India.

BACKGROUND: Sensitization to Aspergillus fumigatus (AS) has been recently described in chronic obstructive pulmonary disease (COPD) patients. However, there is no data on the community prevalence of AS in COPD. OBJECTIVES: To assess the prevalence of AS among COPD subjects. The secondary objectives were to (1) assess the prevalence of allergic bronchopulmonary aspergillosis (ABPA) in COPD and (2) compare the lung function in COPD subjects with and without AS. METHODS: We conducted a cross-sectional study in rural (29 villages) and urban (20 wards) communities in North India. We identified individuals with respiratory symptoms (IRS) through a house-to-house survey using a modified IUATLD questionnaire. We then diagnosed COPD through specialist assessment and spirometry using the GOLD criteria. We assayed A.fumigatus-specific IgE in COPD subjects. In those with A. fumigatus-specific IgE ≥0.35 kUA/L (AS), ABPA was diagnosed with raised serum total IgE and raised A.fumigatus-specific IgG or blood eosinophil count. RESULTS: We found 1315 (8.2%) IRS among 16,071 participants >40 years and diagnosed COPD in 355 (2.2%) subjects. 291 (82.0%) were men and 259 (73.0%) resided in rural areas. The prevalence of AS and ABPA was 17.7% (95% CI, 13.9-21.8) and 6.6% (95% CI, 4.4-8.8). We found a lower percentage predicted FEV1 in COPD subjects with AS than those without (p =.042). CONCLUSIONS: We found an 18% community prevalence of AS in COPD subjects in a specific area in North India. Studies from different geographical areas are required to confirm our findings. The impact of AS and ABPA on COPD requires further research.

Prolonged treatment of dermatophytosis caused by Trichophyton indotinea with terbinafine or itraconazole impacts better outcomes irrespective of mutation in the squalene epoxidase gene.

BACKGROUND: Over the past decades, the increasing incidence of recurrent dermatophytosis associated with terbinafine-resistant Trichophyton has posed a serious challenge in management of dermatophytosis. Independent reports of failure of treatment and high minimum inhibitory concentrations (MIC) of antifungals are available, but data correlating MIC and clinical outcomes is still sparse. Therefore, the present study was conducted to evaluate the outcomes of systemic treatment of dermatophytosis and its correlation with MIC of the etiological agents isolated from such patients. METHODS: Retrospective analysis of 587 consecutive patients with dermatophytosis was done from March 2017 to March 2019. Demographic and clinical details of the patients were noted, along with the results of direct microscopy and fungal culture. The isolates were identified by sequencing the internal transcribed spacer region of rDNA. Antifungal susceptibility testing was performed following the CLSI M38 protocol. Mutation in the squalene epoxidase (SE) gene was detected by DNA sequencing and ARMS-PCR. Based on the culture-positivity and prescribed systemic antifungal, patients were categorised into Group I culture-positive cases treated with systemic terbinafine and Group II culture-positive cases treated with systemic itraconazole, each for a total period of 12 weeks. RESULTS: In the present study, 477 (81.39%) were culture-positive; however, 12 weeks follow-up was available for 294 patients (Group I-157 and Group II-137) who were included for statistical analysis. In both groups [Group I-37/63 (51.4%) and Group II-14/54 (58.3%)], a better cure rate was observed if the initiation of therapy was performed within <6 months of illness. Treatment outcome revealed that if therapy was extended for 8-12 weeks, the odds of cure rate are significantly better (p < .001) with either itraconazole (Odd Ratio-15.5) or terbinafine (Odd Ratio-4.34). Higher MICs for terbinafine were noted in 41 cases (cured-18 and uncured-23) in Group I and 39 cases (cured-16 and uncured-23) in Group II. From cured (Group I-17/18; 94.4% and Group II-14/16; 87.5%) and uncured (Group I-20/23; 86.9% and Group II-21/23; 91.3%) cases had F397L mutation in the SE gene. No significant difference in cure rate was observed in patients with Trichophyton spp. having terbinafine MIC ≥ 1or <1 µg/mL (Group I-p = .712 and Group II-p = .69). CONCLUSION: This study revealed that prolonging terbinafine or itraconazole therapy for beyond 8 weeks rather than the standard 4 weeks significantly increases the cure rate. Moreover, no correlation has been observed between antifungal susceptibility and clinical outcomes. The MIC remains the primary parameter for defining antifungal activity and predicting the potency of antifungal agents against specific fungi. However, predicting therapeutic success based solely on the MIC of a fungal strain is not always reliable, as studies have shown a poor correlation between in vitro data and in vivo outcomes. To address this issue, further correlation of antifungal susceptibility testing (AFST) data with clinical outcomes and therapeutic drug monitoring is needed. It also highlights that initiation of the treatment within <6 months of illness increases cure rates and reduces recurrence. Extensive research is warranted to establish a better treatment regime for dermatophytosis.

The minimal important difference of one-minute-sit-to-stand test in subjects with chronic pulmonary aspergillosis.

BACKGROUND AND OBJECTIVE: There is a need for simple functional test to assess treatment response in chronic pulmonary aspergillosis (CPA) in resource-constrained settings. The one-minute-sit-to-stand test (1-min-STS) is one such test. However, the minimal important difference (MID) for 1-min-STS in subjects with CPA remains unknown. Herein, we estimate the MID for 1-min-STS for CPA subjects. MATERIALS AND METHODS: We retrospectively reviewed the clinical details of CPA subjects treated with oral azoles for 6 months. We included only subjects who completed the 1-min-STS test at baseline and 6 months. We used the change in VAS (visual analogue scale, for overall improvement) as an external anchor. We used the anchor and the distribution (standard deviation-based) methods to determine the MID estimates. We used the anchor-based method only if there was correlation of 0.3 with the 1-min-STS test. RESULTS: One hundred-eight subjects completed the 1-min-STS test at baseline and 6 months. We did not find significant correlation between the change in VAS for overall improvement (r2 = 0.024, P value = 0.809) and the 1-min-STS test. The MID for the 1-min-STS test was 2 repetitions (range, 1.5-2.8 repetitions). CONCLUSION: The MID for the 1-min-STS test in subjects with CPA was 2 repetitions. Future studies using a global rating of change scale as an anchor must confirm our findings.

Evaluation of VITEK MS Version 3.0 MALDI-TOF for the identification of anaerobes, mycobacteria, Nocardia, and moulds.

PURPOSE: The identification of anaerobes, Mycobacterium and Nocardia species, and moulds by MALDI-TOF-MS remains a challenge. This study aimed to evaluate the performance of MALDI-TOF in the identification of these organisms. METHODS: A total of 382 strains, comprising 128 (33.5 %) anaerobes, 126(33.0 %) mycobacterial, 113(29.6 %), mycelial fungi, and 15(3.9 %) Nocardia species were evaluated by VITEK MS Version 3.0. The results were compared with the identification of the isolates by DNA sequence analysis. The DNA sequences used for analysis were the 16S rRNA for anaerobic bacteria, hsp65 gene for mycobacteria, whereas both 16S rRNA and hsp65 gene for Nocardia species, and internal transcribed spacer (ITS) and 28S rRNA gene's D1/D2 regions of fungi. RESULTS: The VITEK-MS accurately identified 78.3 % (299/382) of the strains at the species, and 9.4 % (36/382) at the genus level. Misidentifications were observed in 3.9 % (15/382) isolates. Of isolates tested, 8.4 % (32/382) were not identified by the system, and 7.06 % (27/382) were not included in the IVD database. CONCLUSION: An upgraded VITEK MS V3.0 database provides reasonably accurate and rapid identification of clinically relevant anaerobes, mycobacteria, Nocardia species, and moulds to the species level.

Role of serial fluorodeoxyglucose positron emission tomography-computed tomography (18FDG-PET-CT) in assessing treatment response in treatment naïve chronic pulmonary aspergillosis subjects.

BACKGROUND: The role of 2-deoxy-2-18(F) fluoro-D-glucose (FDG) positron emission tomography (PET)-computed tomography (CT) in assessing treatment response in chronic pulmonary aspergillosis (CPA) remains to be determined. OBJECTIVE: To compare changes in FDG-PET/CT parameters in CPA subjects with treatment success or failure. METHODS: We treated consecutive treatment-naïve CPA subjects with six months of oral itraconazole. We performed PET-CT at baseline and six months. A multi-disciplinary team categorized response as treatment success or failure. We recorded the maximum standardised uptake value (SUVmax), SUVpeak, and total glycolytic activity (TLG). After treatment, FDG uptake similar to the background uptake or ≥13 units decline in Z-score was considered a complete metabolic response (CMR). A >25%, >30%, and > 45% decline in SUVmax, SUVpeak, and TLG was labelled as a partial metabolic response (PMR). A >30%, >30%, or >75% increase in the SUVmax, SUVpeak, and TLG represented progressive metabolic disease. RESULTS: We included 94 CPA subjects (63 males) with a mean age of 46.2 years. A follow-up PET-CT was performed on 77 subjects. We recorded treatment success and failure in 43 and 34 subjects. The median SUVmax at baseline was 6.7, which significantly reduced with treatment. CMR was seen in 18.6% of those with treatment success and none with treatment failure. A higher proportion of subjects with treatment success achieved PMR. 19% of the subjects with treatment success had progressive metabolic disease. CONCLUSION: FGD-PET/CT demonstrated metabolic activity in all CPA subjects. Most PET-CT parameters improved with treatment; however, one-fifth of the subjects were misclassified on PET-CT.

Comparative fitness trade-offs associated with azole resistance in Candida auris clinical isolates.

Multidrug-resistant yeast Candida auris is a serious threat to public health with documented survival in various hospital niches. The dynamics of this survival benefit and its trade off with drug resistance are still unknown for this pathogen. In this study we investigate the oxidative stress response (OSR) in fluconazole-resistant C. auris and compare its relative fitness with fluconazole-susceptible strains. A total of 351 C. auris clinical isolates (61 fluconazole-susceptible and 290 fluconazole-resistant) were screened for stress tolerance by spot assay and 95.08 % fluconazole-susceptible isolates were hyper-resistant to oxidative stress while majority (94.5 %) fluconazole-resistant isolates had lower oxidative tolerance. Expression of Hog1 and Cta1 gene transcript levels and cellular catalase levels were significantly higher in fluconazole-susceptible isolates and a corresponding higher intracellular reactive oxygen species level (iROS) was accumulated in the fluconazole-resistant isolates. Biofilm formation and cell viability under oxidative stress revealed higher biofilm formation and better viability in fluconazole-susceptible isolates. Fluconazole-resistant isolates had higher basal cell wall chitin. On comparison of virulence, the % cytotoxicity in A549 cell line was higher in fluconazole-susceptible isolates and the median survival of the infected larvae in G. mellonella infection model was higher in fluconazole-resistant (5; IQR:4.5-5 days) vs. fluconazole-susceptible C. auris (2; IQR:1.5-2.5 days). All organisms evolve with changes in their environmental conditions, to ensure an optimal balance between proliferation and survival. Development of tolerance to a certain kind of stress example antifungal exposure in yeast can leads to a compensatory decrease in tolerance for other stresses. This study provides useful insights into the comparative fitness and antifungal susceptibility trade off in C. auris. We report a negative association between H2O2 tolerance and fluconazole susceptibility. Using in-vitro cell cytotoxicity and in-vivo survival assays we also demonstrate the higher virulence potential of fluconazole-susceptible C. auris isolates corroborating the negative correlation between susceptibility and pathogen survival or virulence. These findings could also be translated to clinical practice by investigating the possibility of using molecules targeting stress response and fitness regulating pathways for management of this serious infection.

Clinical spectrum, phenotypic and molecular characterization, and antifungal susceptibility of an emerging human pathogen, Acrophialophora, from India.

Acrophialophora is implicated in superficial and invasive infections, especially in immunosuppressed individuals. The present study was undertaken to provide clinical, microbiological, phylogenetic, and antifungal susceptibility testing (AFST) profile of Acrophialophora isolated from India. All the isolates identified as Acrophialophora species at the National Culture Collection for Pathogenic Fungi, Chandigarh, India were revived. Phenotypic and molecular characterization was performed, followed by temperature studies, scanning electron microscopy (SEM), and AFST. We also performed systematic review of all the cases of Acrophialophora species reported till date. A total of nine isolates identified as Acrophialophora species were identified by molecular method as A. fusispora (n = 8) and A. levis (n = 1), from brain abscess (n = 4), respiratory tract (n = 3), and corneal scraping (n = 2). All patients but two had predisposing factors/co-morbidities. Acrophialophora was identified as mere colonizer in one. Temperature studies and SEM divulged variation between both species. Sequencing of the internal transcribed spacer ribosomal DNA and beta-tubulin loci could distinguish species, while the LSU ribosomal DNA locus could not. AFST showed the lowest minimum inhibitory concentrations (MICs) for triazoles and the highest for echinocandins. Systematic literature review revealed 16 cases (11 studies), with ocular infections, pulmonary and central nervous system infections, and A. fusispora was common species. All the patients except three responded well. High MICs were noted for fluconazole, micafungin, and caspofungin. This is the first study delineating clinical, phenotypic, and genotypic characteristics of Acrophialophora species from India. The study highlights microscopic differences between both species and emphasizes the role of molecular methods in precise identification. Triazoles appear to be the most effective antifungals for managing patients.

We describe clinical, phenotypic, and genotypic characteristics of Acrophialophora species. This species causes mild infection to fatal infection in immunosuppressed individuals. Triazoles are effective in treating such infections.

Aspergillus terreus panophthalmitis with orbital cellulitis.

An eleven year old male reported a ten-day history of unilateral pain, redness, and sudden loss of vision. Ophthalmic examination revealed panophthalmitis that did not respond to conventional intravenous antibiotics, and systemic deterioration raised suspicion of a fungal aetiology. However, the worsening of the ocular condition from panophthalmitis to orbital cellulitis upon commencement of amphotericin B suggests the presence of a fastidious microorganism. Aspergillus terreus was isolated from a vitreous tap sample and responded well to intravenous voriconazole, exhibiting a distinct antimicrobial susceptibility spectrum and emphasising its possible involvement in relatively healthy early adolescence. To the author's knowledge, panophthalmitis with orbital cellulitis in early adolescence, without prior ocular insult, paranasal sinus involvement, or immunocompromised status, has not been reported previously.

An interesting report of COVID-19 associated mucormycosis (CAM) cases by two different species of Mucorales.

During surge of COVID-19-associated mucormycosis (CAM), we identified five cases of CAM where two different species of Mucorales were isolated. All had history of diabetes mellitus and presented with clinical features suggesting rhino-orbital mucormycosis. The patients grew different species from their nasal scraping/biopsy samples, Rhizopus arrhizus, R. homothallicus (n = 2); R. homothallicus, Lictheimia corymbifera (n = 1); R. arrhizus, Mucor spp (n = 1); and L. corymbifera, Apophysomyces variabilis (n = 1). All patients underwent surgical and medical (liposomal amphotericin B) treatment. All, except one growing A. variabilis and L. corymbifera survived. Mixed infection by more than one Mucorales in CAM is unique and warrants epidemiological investigation.

Tinea capitis caused by Microsporum canis: A case study of three family members in India, a non-endemic region.

INTRODUCTION: Tinea capitis, a common scalp infection primarily affecting children, is caused by keratinophilic dermatophytic fungi, notably Microsporum and Trichophyton species. Microsporum canis, primarily transmitted from cats and dogs to humans, is rarely reported in non-endemic regions like India. We report a cases involving three family members from Delhi, India, diagnosed with tinea capitis caused by Microsporum canis. The index case, a five-year-old boy, contracted the infection through contact with a cat, while his younger brother and sister acquired it through human-to-human transmission within the family. METHODS: Clinical examination, microscopic analysis, and molecular identification techniques confirmed the diagnosis. Antifungal susceptibility testing revealed sensitivity to itraconazole and terbinafine but resistance to griseofulvin. RESULTS: Treatment with oral terbinafine and topical ketoconazole cream led to successful outcomes for all three patients. Molecular typing confirmed clonality of the isolates, indicating human-to-human transmission. CONCLUSION: This case study underscores the significance of considering atypical sources of infection and human-to-human transmission in the diagnosis and management of tinea capitis caused by Microsporum canis in non-endemic regions. It emphasizes the necessity of thorough contact history assessment and appropriate antifungal therapy for effective control of the infection.

Prevalence of co-existent COVID-19-associated pulmonary aspergillosis (CAPA) and its impact on early mortality in patients with COVID-19-associated pulmonary mucormycosis (CAPM).

BACKGROUND: Data on mixed mould infection with COVID-19-associated pulmonary aspergillosis (CAPA) and COVID-19-associated pulmonary mucormycosis (CAPM) are sparse. OBJECTIVES: To ascertain the prevalence of co-existent CAPA in CAPM (mixed mould infection) and whether mixed mould infection is associated with early mortality (≤7 days of diagnosis). METHODS: We retrospectively analysed the data collected from 25 centres across India on COVID-19-associated mucormycosis. We included only CAPM and excluded subjects with disseminated or rhino-orbital mucormycosis. We defined co-existent CAPA if a respiratory specimen showed septate hyphae on smear, histopathology or culture grew Aspergillus spp. We also compare the demography, predisposing factors, severity of COVID-19, and management of CAPM patients with and without CAPA. Using a case-control design, we assess whether mixed mould infection (primary exposure) were associated with early mortality in CAPM. RESULTS: We included 105 patients with CAPM. The prevalence of mixed mould infection was 20% (21/105). Patients with mixed mould infection experienced early mortality (9/21 [42.9%] vs. 15/84 [17.9%]; p = 0.02) and poorer survival at 6 weeks (7/21 [33.3] vs. 46/77 [59.7%]; p = 0.03) than CAPM alone. On imaging, consolidation was more commonly encountered with mixed mould infections than CAPM. Co-existent CAPA (odds ratio [95% confidence interval], 19.1 [2.62-139.1]) was independently associated with early mortality in CAPM after adjusting for hypoxemia during COVID-19 and other factors. CONCLUSION: Coinfection of CAPA and CAPM was not uncommon in our CAPM patients and portends a worse prognosis. Prospective studies from different countries are required to know the impact of mixed mould infection.

Innate and adaptive immune responses in subjects with CPA secondary to post-pulmonary tuberculosis lung abnormalities.

BACKGROUND: Post-tuberculosis lung abnormality (PTLA) is the most common risk factor for chronic pulmonary aspergillosis (CPA), and 14%-25% of the subjects with PTLA develop CPA. The pathogenesis and the host immune response in subjects with PTLA who develop CPA need to be better understood. METHODS: We prospectively compared the innate and adaptive immune responses mounted by patients of PTLA with or without CPA (controls). We studied the neutrophil oxidative burst (by dihydrorhodamine 123 test), classic (serum C3 and C4 levels) and alternative (mannose-binding lectin [MBL] protein levels) complement pathway, serum immunoglobulins (IgG, IgM and IgA), B and T lymphocytes and their subsets in subjects with PTLA with or without CPA. RESULTS: We included 111 subjects (58 CPA and 53 controls) in the current study. The mean ± SD age of the study population was 42.6 ± 15.7 years. The cases and controls were matched for age, gender distribution and body weight. Subjects with CPA had impaired neutrophil oxidative burst, lower memory T lymphocytes and impaired Th-1 immune response (lower Th-1 lymphocytes) than controls. We found no significant difference between the two groups in the serum complement levels, MBL levels, B-cell subsets and other T lymphocyte subsets. CONCLUSION: Subjects with CPA secondary to PTLA have impaired neutrophil oxidative burst and a lower Th-1 response than controls.

Two promising natural lipopeptides from Bacillus subtilis effectively induced membrane permeabilization in Candida glabrata.

Candida glabrata is an important opportunistic human pathogen well known to develop resistance to antifungal drugs. Due to their numerous desirable qualities, antimicrobial lipopeptides have gained significant attention as promising candidates for antifungal drugs. In the present study, two bioactive lipopeptides (AF4 and AF5 m/z 1071.5 and 1085.5, respectively), coproduced and purified from Bacillus subtilis RLID12.1, consist of seven amino acid residues with lipid moieties. In our previous studies, the reversed phased-HPLC purified lipopeptides demonstrated broad-spectrum of antifungal activities against over 110 Candida albicans, Candida non-albicans and mycelial fungi. Two lipopeptides triggered membrane permeabilization of C. glabrata cells, as confirmed by propidium iodide-based flow cytometry, with PI uptake up to 99% demonstrating fungicidal effects. Metabolic inactivation in treated cells was confirmed by FUN-1-based confocal microscopy. Together, the results indicate that these lipopeptides have potentials to be developed into a new set of antifungals for combating fungal infections.

A novel indirect ELISA for serodiagnosis of mucormycosis using antigens from Rhizopus arrhizus.

BACKGROUND: Due to a delay in diagnosis by conventional techniques and high mortality, the development of a standardised and rapid non-culture-based technique is an unmet need in pulmonary, gastrointestinal, and disseminated forms of mucormycosis. Though limited studies have been conducted for molecular diagnosis, there are no established serologic tests for this highly fatal infection. OBJECTIVE: To develop and evaluate an indirect in-house enzyme-linked immunosorbent assay (ELISA) utilising antigens of Rhizopus arrhizus for detecting anti-Rhizopus antibodies (IgG and IgM) in sera of patients with mucormycosis. METHODS: We extracted both secretory and mycelial Rhizopus antigens using standardised protocols. Bradford assay was used for protein quantification. We then standardised an indirect ELISA using R. arrhizus mycelial and secretory antigens (10.0 µg/mL in bicarbonate buffer pH 9.2) for detecting anti-Rhizopus IgG and IgM antibodies in patient sera. We included patients with mucormycosis, other fungal infections, and healthy controls. Antibody index value (E-value) was calculated for each patient sample. RESULTS: Asparagine broth culture filtrate utilising 85% ammonium sulphate salt fractionation and mycelial homogenate grown in yeast extract peptone dextrose (YPD) broth precipitated with trichloroacetic acid (TCA) yielded a large amount of good-quality protein for the assay. We included 55 patients with mucormycosis (rhino-orbito-cerebral mucormycosis [ROCM, n = 39], pulmonary [n = 15], gastrointestinal [n = 1]), 24 with other fungal infections (probable aspergillosis [n = 14], candidiasis [n = 10]), and healthy controls (n = 16). The sensitivity of the antibody test for diagnosing mucormycosis ranged from 83.6-92.7% for IgG and 72.7-87.3% for IgM, with a specificity of 91.7-92.5% for IgG and 80-82.5% for IgM. The sera from patients with other fungal infections and healthy individuals did not show significant cross-reactivity. CONCLUSION: The detection of anti-Rhizopus IgG antibody performed significantly better in comparison to IgM-based ELISA for diagnosing both ROCM (sensitivity of 84.6% vs. 69.2%) and pulmonary cases (86.6% vs. 80.0%). More extensive studies are required to confirm our findings.

Two promising Bacillus-derived antifungal lipopeptide leads AF4 and AF5 and their combined effect with fluconazole on the in vitro Candida glabrata biofilms.

Introduction: Candida species are endowed with the ability to produce biofilms, which is one of the causes of pathogenicity, as biofilms protect yeasts from antifungal drugs. Candida glabrata (Nakaseomyces glabrata) is one of the most prevalent pathogenic yeasts in humans and a biofilm producer. Methods: The study was aimed at evaluating the combined effects of two highly promising antifungal biomolecules (AF4 and AF5) lipopeptide in nature, chromatographically purified to homogeneity from Bacillus subtilis (B. subtilis) and the standard antifungal fluconazole (at different concentrations) to demonstrate C. glabrata biofilm formation inhibition. Biofilm production and inhibition were evaluated by quantification of the biofilm biomass and metabolic activity using crystal violet (CV) staining and XTT reduction assays, respectively. Microscopic techniques such as confocal scanning laser microscopy (CSLM) and scanning electron microscopy (SEM) were employed to visualize biofilm formation and inhibition. Results and Discussion: Compared to untreated and fluconazole-treated biofilms, an enhanced in vitro anti-biofilm effect of the antifungal lipopeptides AF4/AF5 alone and their combinations with fluconazole was established. The lipopeptides AF4/AF5 alone at 8 and 16 µg/mL exhibited significant biomass and metabolic activity reductions. SEM and CSLM images provided evidence that the lipopeptide exposure results in architectural alterations and a significant reduction of C. glabrata biofilms, whereas (2', 7'-dichlorofluorescin diacetate (DCFDA) and propidium iodide (PI) analyses showed reactive oxygen species (ROS) generation along with membrane permeabilization. The estimation of exopolysaccharides (EPS) in AF4/AF5-treated biofilms indicated EPS reduction. The combinations of fluconazole (64/128 µg/mL) and AF4/AF5 lipopeptide (16 µg/mL) were found to significantly disrupt the mature (24 h) biofilms as revealed by CSLM and SEM studies. The CSLM images of biofilms were validated using COMSTAT. The FTIR-analyses indicate the antibiofilm effects of both lipopeptides on 24 h biofilms to support CSLM and SEM observations. The combinations of fluconazole (64/128 µg/mL) and AF4/AF5 lipopeptide were found to disrupt the mature biofilms; the study also showed that the lipopeptides alone have the potentials to combat C. glabrata biofilms. Taken together, it may be suggested that these lipopeptide leads can be optimized to potentially apply on various surfaces to either reduce or nearly eradicate yeast biofilms.

Carbon substrates promotes stress resistance and drug tolerance in clinical isolates of Candida tropicalis.

Candida tropicalis is a human pathogen and one of the most prevalent non-Candida albicans Candida (NCAC) species causing invasive infections. Azole antifungal resistance in C. tropicalis is also gradually increasing with the increasing incidence of infections. The pathogenic success of C. tropicalis depends on its effective response in the host microenvironment. To become a successful pathogen, cellular metabolism, and physiological status determine the ability of the pathogen to counter diverse stresses inside the host. However, to date, limited knowledge is available on the impact of carbon substrate metabolism on stress adaptation and azole resistance in C. tropicalis. In this study, we determined the impact of glucose, fructose, and sucrose as the sole carbon source on the fluconazole resistance and osmotic (NaCl), oxidative (H2O2) stress adaptation in C. tropicalis clinical isolates. We confirmed that the abundance of carbon substrates influences or increases drug resistance and osmotic and oxidative stress tolerance in C. tropicalis. Additionally, both azole-resistant and susceptible isolates showed similar stress adaptation phenotypes, confirming the equal efficiency of becoming successful pathogens irrespective of drug susceptibility profile. To the best of our knowledge, our study is the first on C. tropicalis to demonstrate the direct relation between carbon substrate metabolism and stress tolerance or drug resistance.