Usefulness of the Non-conventional <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis> Model to Assess <Emphasis Type="Italic">Candida</Emphasis> Virulence

Invasive candidiasis is caused mainly by Candida albicans, but other Candida species have increasing etiologies. These species show different virulence and susceptibility levels to antifungal drugs. The aims of this study were to evaluate the usefulness of the non-conventional model Caenorhabditis elegans to assess the in vivo virulence of seven different Candida species and to compare the virulence in vivo with the in vitro production of proteinases and phospholipases, hemolytic activity and biofilm development capacity. One culture collection strain of each of seven Candida species (C. albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida metapsilosis, Candida orthopsilosis and Candida parapsilosis) was studied. A double mutant C. elegans AU37 strain (glp-4;sek-1) was infected with Candida by ingestion, and the analysis of nematode survival was performed in liquid medium every 24 h until 120 h. Candida establishes a persistent lethal infection in the C. elegans intestinal tract. C. albicans and C. krusei were the most pathogenic species, whereas C. dubliniensis infection showed the lowest mortality. C. albicans was the only species with phospholipase activity, was the greatest producer of aspartyl proteinase and had a higher hemolytic activity. C. albicans and C. krusei caused higher mortality than the rest of the Candida species studied in the C. elegans model of candidiasis.     

Antifungal activity of magnoflorine against <Emphasis Type="Italic">Candida</Emphasis> strains

Candida albicans is a major invasive pathogen, and the development of strains resistant to conventional antifungal agents has been reported in recent years. We evaluated the antifungal activity of 44 compounds against Candida strains. Magnoflorine showed the highest growth inhibitory activity of the tested Candida strains, with a minimum inhibitory concentration (MIC) of 50 μg/mL based on microdilution antifungal susceptibility testing. Disk diffusion assay confirmed the antifungal activity of magnoflorine and revealed that this activity was stable over 3 days compared to those of berberine and cinnamaldehyde. Cytotoxicity testing showed that magnoflorine could potentially be used in a clinical setting because it didn’t have any toxicity to HaCaT cells even in 200 μg/mL of treatment. Magnoflorine at 50 μg/mL inhibited 55.91?±?7.17% of alpha-glucosidase activity which is required for normal cell wall composition and virulence of Candida albicans. Magnoflorine also reduced the formation of C. albicans’ biofilm. Combined treatment with magnoflorine and miconazole decreased the amount of miconazole required to kill various Candida albicans. Therefore, magnoflorine is a good candidate lead compound for novel antifungal agents.     

Invasive Candidiasis in Brescia,Italy: Analysis of Species Distribution and Antifungal Susceptibilities During Seven Years

The aims of this study were to evaluate the epidemiology of nosocomial candidemia in a large teaching hospital in Brescia, Italy, and the in vitro antifungal susceptibility of isolates. We analyzed 196 isolates causing fungemia in patients admitted in our hospital, between January 2009 and December 2015. Strains were identified by VITEK 2 and MALDI-TOF MS. MICs were determined by Sensititre Yeast One_TM. The resistance was defined by using the revised CLSI breakpoints/epidemiological cutoff values to assign susceptibility or wild type to systemic antifungal agents. Most infections were caused by Candida albicans (60%), Candida parapsilosis (15%), Candida glabrata (12%) and Candida tropicalis (6%). The susceptibility rate for fluconazole was 96.5%. Non-Candida species isolates exhibited full susceptibilities to echinocandins according to CLSI breakpoints. Amphotericin B demonstrated excellent activity against all Candida species. Local epidemiological and antifungal susceptibility studies are necessary in order to improve empirical treatment guidelines.     

A Case Report of Penile Infection Caused by Fluconazole- and Terbinafine-Resistant <Emphasis Type="Italic">Candida albicans</Emphasis>

Candida albicans is the most common pathogen that causes balanoposthitis. It often causes recurrence of symptoms probably due to its antifungal resistance. A significant number of balanitis Candida albicans isolates are resistant to azole and terbinafine antifungal agents in vitro. However, balanoposthitis caused by fluconazole- and terbinafine-resistant Candida albicans has rarely been reported. Here, we describe a case of a recurrent penile infection caused by fluconazole- and terbinafine-resistant Candida albicans, as well as the treatments administered to this patient. The isolate from the patient was tested for drug susceptibility in vitro. It was sensitive to itraconazole, voriconazole, clotrimazole and amphotericin B, but not to terbinafine and fluconazole. Thus, oral itraconazole was administrated to this patient with resistant Candida albicans penile infection. The symptoms were improved, and mycological examination result was negative. Follow-up treatment of this patient for 3 months showed no recurrence.     

Boric Acid and Commercial Organoboron Products as Inhibitors of Drug-Resistant <Emphasis Type="Italic">Candida albicans</Emphasis>

Clinical use of boric acid as a topical antifungal in women who have failed standard antifungal therapy with azole drugs has been used sporadically for decades. Our previous in vitro work showing inhibition of Candida albicans growth was conducted on clinical isolates without antifungal drug susceptibility profiling. Here, we report that boric acid restricts growth of drug-resistant Candida albicans and inhibits hyphal growth and diminishes cell volume. The availability of over-the-counter organoboron compounds intended for use as oral nutritional supplements led us to determine if these also were inhibitory toward resistant Candida and show here that they also possess antifungal activity. Candida glabrata was also found to be inhibited by boric acid and organoboron compounds. Further development of organoboron compounds as topical therapeutics is of potential value.     

The continuous changes in the aetiology and epidemiology of invasive candidiasis: from familiar <Emphasis Type="Italic">Candida albicans</Emphasis> to multiresistant <Emphasis Type="Italic">Candida auris</Emphasis>

Recent changes in the aetiology and epidemiology of invasive candidiasis have serious implications for current and future diagnosis, treatment and prognosis. The aim of the current review was to discuss the epidemiology of invasive candidiasis, the distribution of Candida species in different regions of the world, the medical concerns of the changing aetiology and the emergence of antifungal resistance. Overall burden of invasive candidiasis remains high, especially in vulnerable persons, such as the elderly, immunosuppressed or debilitated patients. Moreover, there is a progressive shift in the aetiology of invasive candidiasis from Candida albicans to other species of Candida, probably related to the increased use of azole drugs with a clear trend towards increased antifungal resistance. Finally, the emergence and rise of multiresistant species, such as Candida auris or Candida glabrata, is a major threat making necessary invasive candidiasis worldwide surveillances. These changes have serious implications for the diagnosis, treatment and prognosis of invasive candidiasis. Updated knowledge of the current local epidemiology of invasive candidiasis is critical for the clinical management.     

In Vitro Antifungal Susceptibility of Oral <Emphasis Type="Italic">Candida</Emphasis> Isolates from Patients Suffering from Caries and Chronic Periodontitis

Caries and chronic periodontitis are common oral diseases where a higher Candida colonization is reported. Antifungal agents could be adjuvant drugs for the therapy of both clinical conditions. The aim of the current study has been to evaluate the in vitro activities of conventional and new antifungal drugs against oral Candida isolates from patients suffering from caries and/or chronic periodontitis. In vitro activities of amphotericin B, fluconazole, itraconazole, miconazole, nystatin, posaconazole and voriconazole against 126 oral Candida isolates (75 Candida albicans, 18 Candida parapsilosis, 11 Candida dubliniensis, six Candida guilliermondii, five Candida lipolytica, five Candida glabrata, four Candida tropicalis and two Candida krusei) from 61 patients were tested by the CLSI M27-A3 method. Most antifungal drugs were highly active, and resistance was observed in less than 5% of tested isolates. Miconazole was the most active antifungal drug, being more than 98% of isolates susceptible. Fluconazole, itraconazole, and the new triazoles, posaconazole and voriconazole, were also very active. Miconazole, fluconazole and voriconazole have excellent in vitro activities against all Candida isolates and could represent suitable treatment for a hypothetically adjunctive therapy of caries and chronic periodontitis.     

A Fatal Case of <Emphasis Type="Italic">Candida auris</Emphasis> and <Emphasis Type="Italic">Candida tropicalis</Emphasis> Candidemia in Neutropenic Patient

We report a fatal case of Candida auris that was involved in mixed candidemia with Candida tropicalis, isolated from the blood of a neutropenic patient. Identification of both isolates was confirmed by amplification and sequencing of internal transcribed spacer and D1/D2 domain of large subunit in rRNA gene. Antifungal susceptibility test by E-test method revealed that C. auris was resistant to amphotericin B, anidulafungin, caspofungin, fluconazole, itraconazole and voriconazole. On the other hand, C. tropicalis was sensitive to all antifungal tested. The use of chromogenic agar as isolation media is vital in detecting mixed candidemia.     

Distribution and antifungal susceptibility of yeasts isolates from intensive care unit patients

Yeasts frequently colonize non-sterile sites in the body. The aim of the study was to determine distribution in clinical samples and antifungal susceptibility to five antifungals. From January 2013 through June 2015, 800 isolates were obtained from intensive care unit patients. Candida albicans (58.9%), Candida glabrata (20.4%), Candida krusei (8.6%), and Candida parapsilosis (3.6%) were the leading species. Majority of the C. albicans isolates were susceptible to the fluconazole. Elevated voriconazole minimal inhibitory concentrations (MICs) were observed in isolates exhibiting high fluconazole MICs, most frequently in C. glabrata. Isolates with echinocandins MICs suggesting reduced susceptibility were only sporadic cases with the exception of Trichosporon spp. The amphotericin B MICs were slightly higher for some C. krusei.     

Up-Regulation of Antimicrobial Peptides Gallerimycin and Galiomicin in <Emphasis Type="Italic">Galleria mellonella</Emphasis> Infected with <Emphasis Type="Italic">Candida</Emphasis> Yeasts Displaying Different Virulence Traits

Galleria mellonella has been described as a cheap and an easy-to-reproduce model for the study of fungal infections. We hypothesized that yeasts with higher virulence potential decrease survival and significantly trigger an immune response in G. mellonella through the regulation of innate immunity-related genes encoding antimicrobial peptides (AMPs) such as gallerimycin and galiomicin. Candida albicans SC5314 and Candida dubliniensis CBS 7987, selected because of their different virulence potential, were used for a killing assay followed by the determination of gene expression using qPCR. In vivo results confirmed a significantly (p?=?0.0321) lower pathogenicity for C. dubliniensis than for C. albicans. Accordingly, the induction of C. dubliniensis AMPs was lower at all the selected time points post-infection (1 h, 24 h, 48 h). Moreover, we observed an extremely high regulation of the galiomicin gene compared to the gallerimycin one, suggesting a different role of the tested AMPs in protecting G. mellonella from candidiasis.     

<Emphasis Type="Italic">Candida haemulonii</Emphasis> sensu lato: Update of the Determination of Susceptibility Profile in Argentina and Literature Review

Purpose of review

This review summarizes the information available of Candida haemulonii sensu lato, and updates the in vitro susceptibility profile of the isolates of these species from Argentina. C. haemulonii sensu lato causes fungemia in low frequency in adults and children; however, the knowledge about this emerging yeast is relevant since it is considered as a multi-resistant pathogen.

Recent findings

The discovery of new antifungal molecules, the determination of epidemiological cutoff value and clinical breakpoints for some yeasts of clinical impact, and the update of techniques to determine the in vitro susceptibility profile to yeast have generated some available information, although, for C. haemulonii sensu lato, this information is not always useful for clinical application.

Summary

We determined the susceptibility profile of C. haemulonii sensu lato strains isolated in Argentina, as a first step to establish the epidemiological cutoff values in our region. We also review the current situation in other countries.

     

Yeasts in <Emphasis Type="Italic">Hevea brasiliensis</Emphasis> latex

Yeast abundance and species diversity in the latex of rubber tree Hevea brasiliensis (Willd. ex Juss.) Müll. Arg., on its green leaves, and in soil below the plant were studied. The yeasts present in the fresh latex in numbers of up to 5.5 log(CFU/g) were almost exclusively represented by the species Candida heveicola. This species was previously isolated from Hevea latex in China. In the course of natural modification of the latex (turned from liquid to solid form), yeast diversity increased, while yeast abundance decreased. The yeasts in thickened and solidified latex were represented by typical epiphytic and ubiquitous species: Kodamea ohmeri, Debaryomyces hansenii, Rhodotorula mucilaginosa, and synanthropic species Candida parapsilosis and Cutaneotrichosporon arboriformis. The role of yeasts in latex modification at the initial stages of succession and their probable role in development of antifungal activity in the latex are discussed.     

Emergence of Resistance to Fluconazole in <Emphasis Type="Italic">Candida albicans</Emphasis> Isolated From Vaginal Discharge

Purpose of Review

To provide information about the emergence of fluconazole resistance in Candida albicans isolated from vaginal discharge, in a global context, and to update the in vitro susceptibility profile of this species from Argentina.

Recent Findings

Vulvovaginal candidiasis is the second most common vaginal infection after vaginal bacteriosis. C. albicans remains the prevalent etiological yeast species, and despite antifungal treatment, the rate of recurrence remains high, which may be associated to antifungal resistance.

Summary

Data here presented were obtained from the study of C. albicans strains isolated from patients with clinical signs of vulvovaginal candidiasis from 1996 to 2017. Data obtained could represent the susceptibility profile of C. albicans strains circulating in Argentina and could be of potential usefulness to monitor and guide therapy, and also suggests the need for greater surveillance programs to detect fluconazole resistance over time.

     

<Emphasis Type="Italic">Aeromonas</Emphasis> and <Emphasis Type="Italic">Plesiomonas</Emphasis> species from scarlet ibis (<Emphasis Type="Italic">Eudocimus ruber</Emphasis>) and their environment: monitoring antimicrobial susceptibility and virulence

The present study aimed at evaluating the role of captive scarlet ibises (Eudocimus ruber) and their environment as reservoirs of Aeromonas spp. and Plesiomonas spp., and analyzing the in vitro antimicrobial susceptibility and virulence of the recovered bacterial isolates. Thus, non-lactose and weak-lactose fermenting, oxidase positive Gram-negative bacilli were recovered from cloacal samples (n = 30) of scarlet ibises kept in a conservational facility and from water samples (n = 30) from their environment. Then, the antimicrobial susceptibility, hemolytic activity and biofilm production of the recovered Aeromonas spp. and Plesiomonas shigelloides strains were assessed. In addition, the virulence-associated genes of Aeromonas spp. were detected. Ten Aeromonas veronii bv. sobria, 2 Aeromonas hydrophila complex and 10 P. shigelloides were recovered. Intermediate susceptibility to piperacillin-tazobactam and cefepime was observed in 2 Aeromonas spp. and 1 P. shigelloides, respectively, and resistance to gentamicin was observed in 4 P. shigelloides. The automated susceptibility analysis revealed resistance to piperacillin-tazobactam and meropenem among Aeromonas spp. and intermediate susceptibility to gentamicin among P. shigelloides. All Aeromonas isolates presented hemolytic activity, while 3 P. shigelloides were non-hemolytic. All Aeromonas spp. and 3/10 P. shigelloides were biofilm-producers, at 28 °C, while 10 Aeromonas spp. and 6/10 P. shigelloides produced biofilms, at 37 °C. The most prevalent virulence genes of Aeromonas spp. were asa1 and ascV. Scarlet ibises and their environment harbour potentially pathogenic bacteria, thus requiring monitoring and measures to prevent contamination of humans and other animals.     

2-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole analogues: Antifungal activity in vitro against <Emphasis Type="Italic">Candida</Emphasis> species

The antifungal activity in vitro of the newly synthesized and previously reported compounds of 5-substituted 2-(2,4-dihydroxyphenyl)-1,3,4-thiadiazole series was evaluated. Their structures were confirmed by elemental analyses and IR, ¹H and ¹³C NMR and mass spectra. The azole-resistant clinical isolates of Candida albicans and no-albicans Candida spp. were used in the antifungal tests. Some compounds exhibit higher activities than the comparatively studied antifungal drugs. Amino-1,3,4-thiadiazole derivatives exhibited higher (than other analogues) antifungal effects against Candida no-albicans spp. than against C. albicans. Derivatives with strong antifungal activity have a narrow range of lipophilicity values determined by the Villar approach.     

Antifungal activity of 3-acetylbenzamide produced by actinomycete WA23-4-4 from the intestinal tract of <Emphasis Type="Italic">Periplaneta americana</Emphasis>

Actinomycetes are well-known for producing numerous bioactive secondary metabolites. In this study, primary screening by antifungal activity assay found one actinomycete strain WA23-4-4 isolated from the intestinal tract of Periplaneta americana that exhibited broad spectrum antifungal activity. 16S rDNA gene analysis of strain WA23-4-4 revealed close similarity to Streptomyces nogalater (AB045886) with 86.6% sequence similarity. Strain WA23-4-4 was considered as a novel Streptomyces and the 16s rDNA sequence has been submitted to GenBank (accession no. KX291006). The maximum antifungal activity of WA23-4-4 was achieved when culture conditions were optimized to pH 8.0, with 12% inoculum concentration and 210 ml ISP2 medium, which remained stable between the 5^th and the 9^th day. 3-Acetyl benzoyl amide was isolated by ethyl acetate extraction of WA23-4-4 fermentation broth, and its molecular formula was determined as C₉H₉NO₂ based on MS, IR, ¹H, and ¹³C NMR analyses. The compound showed significant antifungal activity against Candida albicans ATCC 10231 (MIC: 31.25 μg/ml) and Aspergillus niger ATCC 16404 (MIC: 31.25 μg/ml). However, the compound had higher MIC values against Trichophyton rubrum ATCC 60836 (MIC: 500 μg/ml) and Aspergillus fumigatus ATCC 96918 (MIC: 1,000 μg/ml). SEM analysis showed damage to the cell membrane of Candida albicans ATCC 10231 and to the mycelium of Aspergillus niger ATCC 16404 after being treatment with 3-acetyl benzoyl amide. In conclusion, this is the first time that 3-acetyl benzoyl amide has been identified from an actinomycete and this compound exhibited antifungal activity against Candida albicans ATCC 10231 and Aspergillus niger ATCC 16404.     

<Emphasis Type="Italic">Candida auris</Emphasis>: Antifungal Multi-Resistant Emerging Yeast

Purpose of Review

The purpose of this review is to contribute to the knowledge about the existence of Candida auris as an emerging pathogenic fungus, multi-resistant to antifungal, and causing health care-associated infections (HCAI).

Recent Findings

C. auris emerges as yeast with clonal transmission resistance to three families of commonly used antifungals, mainly azoles (fluconazole and voriconazole), diminishing therapeutic options for the treatment of fungal infections. In 2009, C. auris was isolated for the first time in Japan and by the time of this review, it has been reported in different countries in Africa, America, Asia, and Europe.

Summary

It is important to identify yeasts of the Candida genus up to species, to perform susceptibility tests and to implement surveillance, prevention, and control measures, to minimize the global spread of this fungus, due to its impact on public health.

     

The Phenolic Contents and Antimicrobial Activities of Some Marine Algae from the Mediterranean Sea (Algeria)

In this study, three marine algae collected from western coast of algerian mediteranean sea (Ulva lactuca, Dictyota dichotoma, and Corallina elongata) were tested using the agar-well diffusion method for their production of antibacterial and antifungal agents on various organisms that cause diseases of humans and plants (Eschirichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Salmonella sp, Candida albicans, and Penicillium sp.). The total phenol content and antimicrobial activity were determined using different crude seaweeds extracts (methanol, diethylether, and chloroform). The results show that the chloroform extracts of (Ulva lactuca and Corallina elongata) had the highest activity against E. coli and Salmonella sp. The methanol extract obtained from (Ulva lactuca, Dictyota dichotoma, and Corallina elongata) showed antifungal activity for Candida albicans. The results of the study revealed that the seaweeds from Algeria appear to have immense potential as a source of antibacterial and antifungal compounds; they can be used in treating diseases caused by these organisms.     

Characterization of chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) lectin for biological activity

Lectins are proteins that are subject of intense investigations. Information on lectin from chickpea (Cicer arietinum L.) with respect to its biological activities are very limited. In this study, we purified lectin from the seeds of chickpea employing DEAE-cellulose and SP-Sephadex ion exchange chromatography and identified its molecular subunit mass as 35 kDa. The free radical scavenging activity of lectin measured by the DPPH assay has IC₅₀ of 0.88 µg/mL. Lectin exerted antifungal activity against Candida krusei, Fusarium oxysporium oxysporium, Saccharomyces cerevisiae and Candida albicans, while antibacterial activity against E. coli, B. subtilis, S. marcescens and P. aeruginosa. The minimum inhibitory concentrations were 200, 240, 160 and 140 µg for C. krusei, F. oxysporium, S. cerevisiae and C. albicans respectively. Lectin was further examined for its antiproliferative potential against cancerous cell line. The cell viability assay indicated a high inhibition activity on Ishikawa, HepG2, MCF-7 and MDA-MB-231 with IC₅₀ value of 46.67, 44.20, 53.58 and 37.46?µg/mL respectively. These results can provide a background for future research into the benefits of chickpea lectin to pharmacological perspective.     

Genotyping and Persistence of <Emphasis Type="Italic">Candida albicans</Emphasis> from Pregnant Women with Vulvovaginal Candidiasis

Objective

To study Candida albicans genotypes using RAPD and their susceptibility to fluconazole in healthy pregnant women and in vulvovaginal candidiasis (VVC) patients after topical treatment with clotrimazole.

Methods

Vaginal swabs were collected at t = 0 and t = 1 (1 month later) in pregnant women (control group, n = 33), and before (t = 0), at 1 month (t = 1) and at 2 months (t = 2) after clotrimazole treatment in pregnant women with VVC.

Results

Candida albicans was isolated in 30% of healthy pregnant women and 80% of patients with VVC. A high genetic heterogeneity was observed in C. albicans genotypes between individuals. In patients with VVC, topical antifungal treatment with clotrimazole was clinically effective, but only in a 62% C. albicans was eradicated. In patients in which C. albicans was not eradicated, this microorganism persisted for 1 or 2 months after the antifungal treatment. The persistent colonies were not associated with a specific genotype, but they were associated with higher MICs in comparison with colonies isolated from the control group.

Conclusions

Therapy with topical clotrimazole, despite a good clinical outcome, could not eradicate completely C. albicans allowing the persistence of genotypes, with higher MICs to fluconazole. More studies with higher number of patients are needed to validate this preliminary finding.