Emergence of resistance of Candida albicans to clotrimazole in human immunodeficiency virus-infected children: in vitro and clinical correlations

Efficacy of Various Herbal Preparations Against Oral Candida: A Lab-Based Study

Aim

This research was done to analyze the effectiveness related to herbal chemicals in tackling candidiasis.

Materials and Methods

Grounded and ethanol-extracted residues of plants like Avicennia marina, Fagonia indica, Portulaca oleracea, Lawsania inermis, Ziziphus spina, Asphodelus tenuifolius, and Salvadora persica were used in the study. The extract was used against candida species, after which the antibacterial as well as cytotoxicity toward the former were evaluated.

Results

L. inermis and P. oleracea with minimal inhibitory concentration of approx. 10 cenmL had an increased activity against candida species. The preparations of these plants acted against Candida albicans during its stages related to pathogenesis during biofilm production. Superadded infections like in case of bacterial infections along with candida can be difficult to cure. On human RBCs, these plant preparations had no toxicity at their minimum inhibitory concentration level.

Conclusion

We concluded that, as far as being anti-candida and acting against MDR bacterial infections, preparations of plants were effective as an alternative to allopathic drugs.

Molecular Identification of Fungal Species through Multiplex-qPCR to Determine Candidal Vulvovaginitis and Antifungal Susceptibility

Vulvovaginal candidiasis (VVC) is a prevalent condition affecting women worldwide. This study aimed to develop a rapid qPCR assay for the accurate identification of VVC etiological agents and reduced azole susceptibility. One hundred and twenty nine vaginal samples from an outpatient clinic (Bilbao, Spain) were analyzed using culture-based methods and a multiplex qPCR targeting fungal species, which identified Candida albicans as the predominant species (94.2%). Antifungal susceptibility tests revealed reduced azole susceptibility in three (3.48%) isolates. Molecular analysis identified several mutations in genes associated with azole resistance as well as novel mutations in TAC1 and MRR1 genes. In conclusion, we developed a rapid multiplex qPCR assay that detects C. albicans in vulvovaginal specimens and reported new mutations in resistance-related genes that could contribute to azole resistance.

First Synthesis of DBU-Conjugated Cationic Carbohydrate Derivatives and Investigation of Their Antibacterial and Antifungal Activity

The emergence of drug-resistant bacteria and fungi represents a serious health problem worldwide. It has long been known that cationic compounds can inhibit the growth of bacteria and fungi by disrupting the cell membrane. The advantage of using such cationic compounds is that the microorganisms would not become resistant to cationic agents, since this type of adaptation would mean significantly altering the structure of their cell walls. We designed novel, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene)-derived amidinium salts of carbohydrates, which may be suitable for disturbing the cell walls of bacteria and fungi due to their quaternary ammonium moiety. A series of saccharide-DBU conjugates were prepared from 6-iodo derivatives of d-glucose, d-mannose, d-altrose and d-allose by nucleophilic substitution reactions. We optimized the synthesis of a d-glucose derivative, and studied the protecting group free synthesis of the glucose-DBU conjugates. The effect of the obtained quaternary amidinium salts against Escherichia coli and Staphylococcus aureus bacterial strains and Candida albicans yeast was investigated, and the impact of the used protecting groups and the sugar configuration on the antimicrobial activity was analyzed. Some of the novel sugar quaternary ammonium compounds with lipophilic aromatic groups (benzyl and 2-napthylmethyl) showed particularly good antifungal and antibacterial activity.

Susceptibility to Clotrimazole of Candida spp. Isolated from the Genitourinary System-A Single Center Study

The aim of this study was to determine the susceptibility to clotrimazole of 125 isolates of Candida spp. originated from the genitourinary system of hospitalized patients as well as outpatients, tested in the mycological laboratory of Wroclaw Medical University in the years 1999–2018. The minimal inhibitory concentrations of clotrimazole and fluconazole were determined with the use of the microdilution method according to EUCAST, and the MFC was determined by subsequent subculture on Sabouraud agar. For the tested population of Candida yeasts, the MIC values of clotrimazole ranged from 0.008 to 8 mg/L, and MIC90 was 1 mg/L, whereas MIC50 was 0.008 mg/L. The minimal fungicidal concentration ranged between 1 and >8 mg/L. The great majority of the isolates (88%; 110/125) displayed MIC < 1 mg/L and were classified as WT (wild-type), whereas MIC ≥ 1 mg/L was determined for 2/61 (3.2%) isolates of C. albicans, 9/38 (23.6%) of C. glabrata, 1/2 of C. tropicalis, and 3/3 of C. guilliermondii. Six isolates (four of C. glabrata and two of C. albicans), defined as non-WT for clotrimazole, were classified as resistant to fluconazole, according to CBP from EUCAST. The isolates with elevated MIC to clotrimazole originated mostly from patients of the pediatric hematology unit, and their proportion in this population amounted to 17.8% (13 out of 73 isolates). In contrast, among strains from ambulatory patients, the highest observed MIC value was 1 mg/L (1 out of 37 isolates; 2.7%). The data obtained correlate well with those of most published studies on the in vitro susceptibility of Candida spp. to clotrimazole, which is usually very high. However, the existence of reports regarding the growing prevalence of resistant isolates has also to be noted. These results support the need for routinely checking the susceptibility of Candida clinical isolates to this imidazole derivative.

Antifungal Susceptibility Pattern of Candida Isolates: A Comparison in H.I.V. Positive and Negative Patients from A Tertiary Care Hospital of Northern India

Candidiasis is recognized as a significant cause of morbidity, especially in immunocompromised individuals. An epidemiologic change in Candida species and emergence of resistance can impact the usage of antifungal agents as empirical therapy for Candidiasis in patients with or without AIDS. The present study was done to find out: i) The species of Candida isolated from H.I.V. and Non-HIV infected patients. ii) The resistance pattern of these Candida isolates to antifungal agents. A total of 160 Candida species isolates (80 isolates each from H.I.V. and Non-HIV infected patients) were characterized. Identification of yeast isolates was made by standard procedures including morphology (Staib agar, cornmeal agar, CHROMagar), germ tube test, fermentation, and assimilation of sugars and growth at 42°C. In addition, sensitivity testing was done using the broth microdilution method (M27-A2) as per the C.L.S.I. guidelines against amphotericin B, nystatin, voriconazole, fluconazole, ketoconazole, and itraconazole. In both the groups, i.e., H.I.V. and Non-HIV infected patients, Candida albicans was the most common species (61.2 % and 85 % respectively), followed by Candida guilliermondi (16.2 % and 5 %), Candida tropicalis (5 % and 3.7 %), Candida krusei (5% and 2.5 %), Candida dubliniensis 1(5 % and 1.2 %) and others. Among HIV infected patients fluconazole resistance was 16.25%, ketoconazole 13.5%, clotrimazole 12.5%, itraconazole 6.25 %. In the non-HIV infected group, fluconazole resistance was 8.75% and itraconazole 1.25%. For the appropriate treatment of Candida infections, antifungal susceptibility has become an essential tool, especially in the present scenario of increasing resistance.

In vivo active organometallic-containing antimycotic agents

Fungal infections represent a global problem, notably for immunocompromised patients in hospital, COVID-19 patient wards and care home settings, and the ever-increasing emergence of multidrug resistant fungal strains is a sword of Damocles hanging over many healthcare systems. Azoles represent the mainstay of antifungal drugs, and their mode of action involves the binding mode of these molecules to the fungal lanosterol 14α-demethylase target enzyme. In this study, we have prepared and characterized four novel organometallic derivatives of the frontline antifungal drug fluconazole (1a-4a). Very importantly, enzyme inhibition and chemogenomic profiling demonstrated that lanosterol 14α-demethylase, as for fluconazole, was the main target of the most active compound of the series, (N-(ferrocenylmethyl)-2-(2,4-difluorophenyl)-2-hydroxy-N-methyl-3-(1H-1,2,4-triazol-1-yl)propan-1-aminium chloride, 2a). Transmission electron microscopy (TEM) studies suggested that 2a induced a loss in cell wall integrity as well as intracellular features ascribable to late apoptosis or necrosis. The impressive activity of 2a was further confirmed on clinical isolates, where antimycotic potency up to 400 times higher than fluconazole was observed. Also, 2a showed activity towards azole-resistant strains. This finding is very interesting since the primary target of 2a is the same as that of fluconazole, emphasizing the role played by the organometallic moiety. In vivo experiments in a mice model of Candida infections revealed that 2a reduced the fungal growth and dissemination but also ameliorated immunopathology, a finding suggesting that 2a is active in vivo with added activity on the host innate immune response.

Types of yeasts that cause vulvovaginal candidiasis in chronic users of corticosteroids

The current study aims to compare between the types of yeasts that cause vulvovaginal candidiasis (VVC) in women using corticosteroid medication compared to nonusers and estimate their sensitivity to available commercial antifungal agents. In a descriptive analytical cross-sectional study, we recruited 41 chronic corticosteroid users diagnosed clinically to have VVC from Women's Health Hospital, Assiut University, Egypt. Forty-seven age-matched women with VVC were recruited as a control group. Full history and clinical examination were performed. Vaginal sterile swab obtained from the vagina of each participant was subjected to direct Gram-stained smear examination as well as a culture on Sabouraud's glucose agar and HiCrome Candida agar. Further identification of the isolates was done using traditional methods. Fifty out of 88 samples (56.8%) were positive in culture including 25 samples (61%) from corticosteroid users group and 25 (53.2%) from noncorticosteroid users with no statistically significant difference (P = .302). The chronic corticosteroid users had more incidence of recurrent VVC as compared to nonusers (65.9% vs 40.4%, respectively) (P = .015). There was a significantly higher rate of non-Candida albicans (NCA) infections in corticosteroid users compared with nonusers (48% vs 20%, respectively) (P = .036). A higher significant difference in resistance of the isolates against clotrimazole (P = .003) and ketoconazole (P = .017) was demonstrated in corticosteroid users compared to nonusers. Thus, chronic corticosteroid use causes frequent attacks of VVC and increases the frequency of infection by NCA strains. Also, it increases resistance to common antifungal agents especially azole group.

Low prevalence of antifungal resistant Candida africana, in the C. albicans complex causing vulvovaginal candidiasis

The Candida (C.) albicans complex includes C. albicans, C. dubliniensis, C. stellatoidea, and C. africana, with the last mentioned as an important emerging agent of vulvovaginal candidiasis (VVC). The aim of the study was to identify C. africana and C. dubliniensis and assess their drug susceptibility in vaginitis. One-hundred Candida isolates of the C. albicans complex from women diagnosed with vaginitis and from vaginal samples in the culture collection of a medical mycology laboratory were examined. Species of the C. albicans complex were identified with conventional and molecular methods using polymerase chain reaction (PCR) for amplification and sequencing of the internal transcribed spacer (ITS) region, PCR for partial amplification of hyphal wall protein 1 (HWP1) gene and duplex PCR. The effects of antifungal drugs were evaluated according to standard broth microdilution protocols.

Ninety-seven C. albicans (97%) and three C. africana (3%) isolates were identified. Results of susceptibility testing revealed one isolate of C. africana to be resistant to both clotrimazole and fluconazole, and one showed reduced susceptibility to itraconazole.

Identification of Candida species especially C. africana in vaginitis is crucial, there are varying levels of resistance to antifungal drugs.

Clotrimazole-Loaded Mediterranean Essential Oils NLC: A Synergic Treatment of Candida Skin Infections

The increasing development of resistance of Candida species to traditional drugs represents a great challenge to the medical field for the treatment of skin infections. Essential oils were recently proposed to increase drug effectiveness. Herein, we developed and optimized (2³ full factorial design) Mediterranean essential oil (Rosmarinus officinalis, Lavandula x intermedia “Sumian”, Origanum vulgare subsp. hirtum) lipid nanoparticles for clotrimazole delivery, exploring the potential synergistic effects against Candida spp. Small sized nanoparticles (<100 nm) with a very broad size distribution (PDI < 0.15) and long-term stability were successfully prepared. Results of the in vitro biosafety on HaCaT (normal cell line) and A431 (tumoral cell line), allowed us to select Lavandula and Rosmarinus as anti-proliferative agents with the potential to be used as co-adjuvants in the treatment of non-tumoral proliferative dermal diseases. Results of calorimetric studies on biomembrane models, confirmed the potential antimicrobial activity of the selected oils due to their interaction with membrane permeabilization. Nanoparticles provided a prolonged in vitro release of clotrimazole. In vitro studies against Candida albicans, Candida krusei and Candida parapsilosis, showed an increase of the antifungal activity of clotrimazole-loaded nanoparticles prepared with Lavandula or Rosmarinus, thus confirming nanostructured lipid carriers (NLC) containing Mediterranean essential oils represent a promising strategy to improve drug effectiveness against topical candidiasis.

Evaluation of the antifungal efficacy of different concentrations of Curcuma longa on Candida albicans: An in vitro study

Background

Candidal infections have increased significantly in denture wearers, especially in immunocompromised patients. The increase in resistance to existing antifungal drugs and number of patients at risk, in conjunction with the restricted number of commercially available antifungal drugs that still present many side effects, are the cause for this problem. These limitations emphasize the need to develop new and more effective antifungal agents with lesser side effects.

Materials and Methods

The present study was undertaken to investigate the possible antifungal action of the alcoholic extract of different concentrations of Curcuma longa on four dilutions of Candida albicans (1:10, 1:20, 1:40 and 1:80) and to determine its minimum inhibitory concentration (MIC) and minimum fungicidal concentration using Sabouraud's agar medium.

Results

There was complete inhibition of the growth of all four dilutions of Candida at a concentration of 800 μl which is considered as the MIC of alcoholic extract of turmeric on C. albicans, and the minimum fungicidal concentration was at 1600 μl.

Conclusion

This study indicates a potent antifungal action of C. longa against C. albicans.

Molecular Identification and Antifungal Susceptibility Pattern of Non-albicans Candida Species Isolated from Vulvovaginal Candidiasis

Background

Vulvovaginal candidiasis (VVC) is an important health problem caused by Candida spp. The aim of this study was molecular identification, phylogenetic analysis, and evaluation of antifungal susceptibility of non-albicans Candida isolates from VVC.

Methods

Vaginal secretion samples were collected from 550 vaginitis patients at Sayyad Shirazi Medical and Educational Center of Gorgan (Golestan Province, Iran) from May to October 2015. Samples were analyzed using conventional mycological and molecular approaches. Clinical isolates were analyzed with specific PCR using CGL primers, and the internal transcribed spacer region and the D1-D2 domain of the large-subunit rRNA gene were amplified and sequenced. Susceptibility to amphotericin B, fluconazole, itraconazole, and clotrimazole was determined by the guidelines of the Clinical and Laboratory Standard Institute.

Results

In total, 35 non-albicans Candida isolates were identified from VVC patients. The isolates included 27 strains of Candida glabrata (77.1%), 5 Candida krusei (Pichia kudriavzevii; 14.3%), 2 Candida kefyr (Kluyveromyces marxianus; 5.7%), and 1 Candida lusitaniae (Clavispora lusitaniae; 2.9%). The fungicides itraconazole and amphotericin B were effective against all species. One isolate of C. glabrata showed resistance to fluconazole and clotrimazole, and 26 isolates of C. glabrata indicated dose-dependent susceptibility to fluconazole. C. lusitaniae was susceptible in a dose-dependent manner to fluconazole and resistant to clotrimazole.

Conclusion

Non-albicans Candida spp. are common agents of vulvovaginitis, and C. glabrata is the most common species in the tested patients.

Synergy between azoles and 1,4-dihydropyridine derivative as an option to control fungal infections

With emerging fungal infections and developing resistance, there is a need for understanding the mechanisms of resistance as well as its clinical impact while planning the treatment strategies. Several approaches could be taken to overcome the problems arising from the management of fungal diseases. Besides the discovery of novel effective agents, one realistic alternative is to enhance the activity of existing agents. This strategy could be achieved by combining existing antifungal agents with other bioactive substances with known activity profiles (combination therapy). Azole antifungals are the most frequently used class of substances used to treat fungal infections. Fluconazole is often the first choice for antifungal treatment. The aim of this work was to study potential synergy between azoles and 1,4-dihydropyridine-2,3,5-tricarboxylate (termed derivative H) in order to control fungal infections. This article points out the synergy between azoles and newly synthesized derivative H in order to fight fungal infections. Experiments confirmed the role of derivative H as substrate/inhibitor of fungal transporter Cdr1p relating to increased sensitivity to fluconazole. These findings, plus decreased expression of ERG11, are responsible for the synergistic effect.

Antimicrobial activity of various ethanolic plant extracts against pathogenic multi drug resistant Candida spp

A total of 50 Candida isolates were isolated and identified from clinical specimens and these were tested for resistance to various antifungal drugs. It was observed multi-drug resistance in all candida isolates by 84%, 62%, 60%, 76%, 46, 30%, and 22% against fluconazole, clotrimazole, Amphotericin B, itraconazole, ketoconazole, miconazole and nystatin tested respectively. The isolates, which were found to be resistant to antifungal drugs were selected and subjected to antifungal testing against six ethanolic plants, extract namely Azadiracta indica, Allium sativum, Cordia dichotoma Ocimum sanctum, Syzygium cumini and Trigonella foenum grecum. All the plant extracts tested were found to effective against all MDR Candida isolates with inhibition zone ranging from 10- 18mm in diameter. Ethanolic extract of Allium sativum was observed most effective against the isolates among all the plants extracts tested. The minimum inhibitory concentration (MIC) of all ethanolic plant extract was recorded ranging from 1.56-25mg/ml against MDR candida isolates. Phytochemical analysis of the alcoholic plant extracts revealed the presence of alkaloid, flavanoid, glycosoid, phenol; phenol, tannins, saponins in all the plants studied. The present study may be successful in identifying the plants with different antimicrobial activity. These plants containing various phytochemicals may be exploited in the treatment of infectious diseases caused by drug-resistant microorganisms.

Molecular Mechanism of Drug Resistance

The treatment of microbial infections has suffered greatly in this present century of pathogen dominance. Inspite of extensive research efforts and scientific advancements, the worldwide emergence of microbial tolerance continues to plague survivability. The innate property of microbe to resist any antibiotic due to evolution is the virtue of intrinsic resistance. However, the classical genetic mutations and extrachromosomal segments causing gene exchange attribute to acquired tolerance development. Rampant use of antimicrobials causes certain selection pressure which increases the resistance frequency. Genomic duplication, enzymatic site modification, target alteration, modulation in membrane permeability, and the efflux pump mechanism are the major contributors of multidrug resistance (MDR), specifically antibiotic tolerance development. MDRs will lead to clinical failures for treatment and pose health crisis. The molecular mechanisms of antimicrobial resistance are diverse as well as complex and still are exploited for new discoveries in order to prevent the surfacing of “superbugs.” Antimicrobial chemotherapy has diminished the threat of infectious diseases to some extent. To avoid the indiscriminate use of antibiotics, the new ones licensed for use have decreased with time. Additionally, in vitro assays and genomics for anti-infectives are novel approaches used in resolving the issues of microbial resistance. Proper use of drugs can keep it under check and minimize the risk of MDR spread.

Candida antifungal drug resistance in sub-Saharan African populations: A systematic review

Background: Candida infections are responsible for increased morbidity and mortality rates in at-risk patients, especially in developing countries where there is limited access to antifungal drugs and a high burden of HIV co-infection.  Objectives: This study aimed to identify antifungal drug resistance patterns within the subcontinent of Africa.  Methods: A literature search was conducted on published studies that employed antifungal susceptibility testing on clinical Candida isolates from sub-Saharan African countries using Pubmed and Google Scholar.  Results: A total of 21 studies from 8 countries constituted this review. Only studies conducted in sub-Saharan Africa and employing antifungal drug susceptibility testing were included. Regional differences in Candida species prevalence and resistance patterns were identified.  Discussion: The outcomes of this review highlight the need for a revision of antifungal therapy guidelines in regions most affected by Candida drug resistance.  Better controls in antimicrobial drug distribution and the implementation of regional antimicrobial susceptibility surveillance programmes are required in order to reduce the high Candida drug resistance levels seen to be emerging in sub-Saharan Africa.

Clotrimazole Drug Resistance in Candida glabrata Clinical Isolates Correlates with Increased Expression of the Drug:H(+) Antiporters CgAqr1, CgTpo1_1, CgTpo3, and CgQdr2

For years, antifungal drug resistance in Candida species has been associated to the expression of ATP-Binding Cassette (ABC) multidrug transporters. More recently, a few drug efflux pumps from the Drug:H(+) Antiporter (DHA) family have also been shown to play a role in this process, although to date only the Candida albicans Mdr1 transporter has been demonstrated to be relevant in the clinical acquisition of antifungal drug resistance. This work provides evidence to suggest the involvement of the C. glabrata DHA transporters CgAqr1, CgQdr2, CgTpo1_1, and CgTpo3 in the clinical acquisition of clotrimazole drug resistance. A screening for azole drug resistance in 138 C. glabrata clinical isolates, from patients attending two major Hospitals in Portugal, was performed. Based on this screening, 10 clotrimazole susceptible and 10 clotrimazole resistant isolates were selected for further analysis. The transcript levels of CgAQR1, CgQDR2, CgTPO1_1, and CgTPO3 were found to be significantly up-regulated in resistant isolates when compared to the susceptible ones, with a level of correlation that was found to be similar to that of CgCDR2, an ABC gene known to be involved in the clinical acquisition of resistance. As a proof-of-concept experiment, the CgTPO3 gene was deleted in an azole resistant C. glabrata isolate, exhibiting high levels of expression of this gene. The deletion of CgTPO3 in this isolate was found to lead to decreased resistance to clotrimazole and fluconazole, and increased accumulation of azole drugs, thus suggesting the involvement of this transporter in the manifestation of azole resistance.

Spectrum and the In Vitro Antifungal Susceptibility Pattern of Yeast Isolates in Ethiopian HIV Patients with Oropharyngeal Candidiasis

Background. In Ethiopia, little is known regarding the distribution and the in vitro antifungal susceptibility profile of yeasts. Objective. This study was undertaken to determine the spectrum and the in vitro antifungal susceptibility pattern of yeasts isolated from HIV infected patients with OPC. Method. Oral pharyngeal swabs taken from oral lesions of study subjects were inoculated onto Sabouraud Dextrose Agar. Yeasts were identified by employing conventional test procedures and the susceptibility of yeasts to antifungal agents was evaluated by disk diffusion assay method. Result. One hundred and fifty-five yeast isolates were recovered of which 91 isolates were from patients that were not under HAART and 64 were from patients that were under HAART. C. albicans was the most frequently isolated species followed by C. glabrata, C. tropicalis, C. krusei, C. kefyr, Cryptococcus laurentii, and Rhodotorula species. Irrespective of yeasts isolated and identified, 5.8%, 5.8%, 12.3%, 8.4%, 0.6%, and 1.3% of the isolates were resistant to amphotericin B, clotrimazole, fluconazole, ketoconazole, miconazole, and nystatin, respectively. Conclusion. Yeast colonization rate of 69.2% and 31% resistance to six antifungal agents was documented. These highlight the need for nationwide study on the epidemiology of OPC and resistance to antifungal drugs.

Mechanisms of resistance to fluconazole in Candida albicans clinical isolates from Iranian HIV-infected patients with oropharyngeal candidiasis

OBJECTIVES

The opportunistic pathogen Candida albicans is the major agent of oropharyngeal candidiasis (OPC) in HIV/AIDS patients. The increased use of fluconazole can lead to the emergence of azole-resistant strains and treatment failures in PLWH (people living with HIV) receiving long-term therapy for OPC. The purpose of this study was to evaluate CDR1, CDR2, MDR1, and ERG11 gene expression in C. albicans clinically isolated from HIV-infected patients in Iran.

PATIENTS AND METHODS

In this study, we evaluated the molecular mechanisms of azole resistance in 20 fluconazole-resistant C. albicans isolates obtained from Iranian HIV-infected patients with oropharyngeal candidiasis by Real-Time polymerase chain reaction.

RESULTS

The overexpression of drug efflux pump CDR1 gene was found to be the major resistance mechanism observed in these isolates. The overexpression of the CDR1 gene correlated strongly with increasing resistance to fluconazole (P<0.05). Additionally, an increased level of mRNA in ERG11 was not observed in any of the tested isolates.

CONCLUSIONS

Our findings suggested that the CDR1 gene expression to fluconazole resistance in C. albicans is greater than other known genes.

Prevalence of oral candidiasis in HIV/AIDS children in highly active antiretroviral therapy era. A literature analysis

SummaryHighly active antiretroviral therapy has decreased the morbidity and mortality related to HIV infection, including oral opportunistic infections. This paper offers an analysis of the scientific literature on the epidemiological aspects of oral candidiasis in HIV-positive children in the combination antiretroviral therapy era. An electronic databases search was made covering the highly active antiretroviral therapy era (1998 onwards). The terms used were oral lesions, oral candidiasis and their combination with highly active antiretroviral therapy and HIV/AIDS children. The following data were collected from each paper: year and country in which the investigation was conducted, antiretroviral treatment, oral candidiasis prevalence and diagnostic parameters (clinical or microbiological). Prevalence of oral candidiasis varied from 2.9% in American HIV-positive children undergoing highly active antiretroviral therapy to 88% in Chilean HIV-positive children without antiretroviral therapy. With respect to geographical location and antiretroviral treatment, higher oral candidiasis prevalence in HIV-positive children on combination antiretroviral therapy/antiretroviral therapy was reported in African children (79.1%) followed by 45.9% reported in Hindu children. In HIV-positive Chilean children on no antiretroviral therapy, high oral candidiasis prevalence was reported (88%) followed by Nigerian children (80%). Oral candidiasis is still frequent in HIV-positive children in the highly active antiretroviral therapy era irrespective of geographical location, race and use of antiretroviral therapy.

Development of an antifungal denture adhesive film for oral candidiasis utilizing hot melt extrusion technology

OBJECTIVES

The overall goal of this research was to produce a stable hot-melt extruded 'Antifungal Denture Adhesive film' (ADA) system for the treatment of oral candidiasis.

METHODS

The ADA systems with hydroxypropyl cellulose (HPC) and/or polyethylene oxide (PEO) containing clotrimazole (10%) or nystatin (10%) were extruded utilizing a lab scale twin-screw hot-melt extruder. Rolls of the antifungal-containing films were collected and subsequently die-cut into shapes adapted for a maxillary (upper) and mandibular (lower) denture.

RESULTS

Differential scanning calorimeter and powder X-ray diffraction results indicated that the crystallinity of both APIs was changed to amorphous phase after hot-melt extrusion. The ADA system, containing blends of HPC and PEO, enhanced the effectiveness of the antimicrobials a maximum of fivefold toward the inhibition of cell adherence of Candida albicans to mammalian cells/Vero cells. Remarkably, a combination of the two polymers without drug also demonstrated a 38% decrease in cell adhesion to the fungi due to the viscosity and the flexibility of the polymers. Drug-release profiles indicated that both drug concentrations were above the minimum inhibitory concentration (MIC) for C. albicans within 10 min and was maintained for over 10 h. In addition, based on the IC50 and MIC values, it was observed that the antifungal activities of both drugs were increased significantly in the ADA systems.

CONCLUSIONS

Based on these findings, the ADA system may be used for primary, prophylaxis or adjunct treatment of oral or pharyngeal candidiasis via controlled release of the antifungal agent from the polymer matrix.

Albumin stabilized silver nanoparticles–clotrimazole β-cyclodextrin hybrid nanocomposite for enriched anti-fungal activity in normal and drug resistant Candida cells

Nanohybrid based strategy to counter the problem of drug resistance inCandidacells.

Clotrimazole as a potent agent for treating the oomycete fish pathogen Saprolegnia parasitica through inhibition of sterol 14α-demethylase (CYP51)

A candidate CYP51 gene encoding sterol 14α-demethylase from the fish oomycete pathogen Saprolegnia parasitica (SpCYP51) was identified based on conserved CYP51 residues among CYPs in the genome. It was heterologously expressed in Escherichia coli, purified, and characterized. Lanosterol, eburicol, and obtusifoliol bound to purified SpCYP51 with similar binding affinities (Ks, 3 to 5 μM). Eight pharmaceutical and six agricultural azole antifungal agents bound tightly to SpCYP51, with posaconazole displaying the highest apparent affinity (Kd, ≤3 nM) and prothioconazole-desthio the lowest (Kd, ∼51 nM). The efficaciousness of azole antifungals as SpCYP51 inhibitors was confirmed by 50% inhibitory concentrations (IC50s) of 0.17 to 2.27 μM using CYP51 reconstitution assays. However, most azole antifungal agents were less effective at inhibiting S. parasitica, Saprolegnia diclina, and Saprolegnia ferax growth. Epoxiconazole, fluconazole, itraconazole, and posaconazole failed to inhibit Saprolegnia growth (MIC100, >256 μg ml(-1)). The remaining azoles inhibited Saprolegnia growth only at elevated concentrations (MIC100 [the lowest antifungal concentration at which growth remained completely inhibited after 72 h at 20°C], 16 to 64 μg ml(-1)) with the exception of clotrimazole, which was as potent as malachite green (MIC100, ∼1 μg ml(-1)). Sterol profiles of azole-treated Saprolegnia species confirmed that endogenous CYP51 enzymes were being inhibited with the accumulation of lanosterol in the sterol fraction. The effectiveness of clotrimazole against SpCYP51 activity (IC50, ∼1 μM) and the concentration inhibiting the growth of Saprolegnia species in vitro (MIC100, ∼1 to 2 μg ml(-1)) suggest that clotrimazole could be used against Saprolegnia infections, including as a preventative measure by pretreatment of fish eggs, and for freshwater-farmed fish as well as in leisure activities.

Occurrence and characterization of Candida nivariensis from a culture collection of Candida glabrata clinical isolates in Malaysia

BACKGROUND

Candida nivariensis and C. bracarensis have been recently identified as emerging yeast pathogens which are phenotypically indistinguishable from C. glabrata. However, there is little data on the prevalence and antifungal susceptibilities of these species.

OBJECTIVE

This study investigated the occurrence of C. nivariensis and C. bracarensis in a culture collection of 185 C. glabrata isolates at a Malaysian teaching hospital.

METHODS

C. nivariensis was discriminated from C. glabrata using a PCR assay as described by Enache-Angoulvant et al. (J Clin Microbiol 49:3375-9, 2011). The identity of the isolates was confirmed by sequence analysis of the D1D2 domain and internal transcribed spacer region of the yeasts. The isolates were cultured on Chromogenic CHROMagar Candida (®) agar (Difco, USA), and their biochemical and enzymic profiles were determined. Antifungal susceptibilities of the isolates against amphotericin B, fluconazole, voriconazole and caspofungin were determined using E tests. Clotrimazole MICs were determined using a microbroth dilution method.

RESULTS

There was a low prevalence (1.1 %) of C. nivariensis in our culture collection of C. glabrata. C. nivariensis was isolated from a blood culture and vaginal swab of two patients. C. nivariensis grew as white colonies on Chromogenic agar and demonstrated few positive reactions using biochemical tests. Enzymatic profiles of the C. nivariensis isolates were similar to that of C. glabrata. The isolates were susceptible to amphotericin B, fluconazole, voriconazole and caspofungin. Clotrimazole resistance is suspected in one isolate.

CONCLUSION

This study reports for the first time the emergence of C. nivariensis in our clinical setting.

Clotrimazole as a pharmaceutical: past, present and future

Clotrimazole is a broad-spectrum antimycotic drug mainly used for the treatment of Candida albicans and other fungal infections. A synthetic, azole antimycotic, clotrimazole is widely used as a topical treatment for tinea pedis (athlete's foot), as well as vulvovaginal and oropharyngeal candidiasis. It displays fungistatic antimycotic activity by targeting the biosynthesis of ergosterol, thereby inhibiting fungal growth. As well as its antimycotic activity, clotrimazole has become a drug of interest against several other diseases such as sickle cell disease, malaria and some cancers. It has also been combined with other molecules, such as the metals, to produce clotrimazole complexes that show improved pharmacological efficacy. Moreover, several new, modified-release pharmaceutical formulations are also undergoing development. Clotrimazole is a very well-tolerated product with few side effects, although there is some drug resistance appearing among immunocompromised patients. Here, we review the pharmaceutical chemistry, application and pharmacology of clotrimazole and discuss future prospects for its further development as a chemotherapeutic agent.

Multi-drug resistant oral Candida species isolated from HIV-positive patients in South Africa and Cameroon

Candida species are a common cause of infection in immune-compromised HIV-positive individuals, who are usually treated with the antifungal drug, fluconazole, in public hospitals in Africa. However, information about the prevalence of drug resistance to fluconazole and other antifungal agents on Candida species is very limited. This study examined 128 Candida isolates from South Africa and 126 Cameroonian Candida isolates for determination of species prevalence and antifungal drug susceptibility. The isolates were characterized by growth on chromogenic and selective media and by their susceptibility to 9 antifungal drugs tested using the TREK™ YeastOne9 drug panel (Thermo Scientific, USA). Eighty-three percent (82.8%) of South African isolates were Candida albicans (106 isolates), 9.4% were Candida glabrata (12 isolates), and 7.8% were Candida dubliniensis (10 isolates). Of the Cameroonian isolates, 73.02% were C. albicans (92 isolates); 19.05% C. glabrata (24 isolates); 3.2% Candida tropicalis (4 isolates); 2.4% Candida krusei (3 isolates); 1.59% either Candida kefyr, Candida parapsilopsis, or Candida lusitaneae (2 isolates); and 0.79% C. dubliniensis (1 isolate). Widespread C. albicans resistance to azoles was detected phenotypically in both populations. Differences in drug resistance were seen within C. glabrata found in both populations. Echinocandin drugs were more effective on isolates obtained from the Cameroon than in South Africa. A multiple-drug resistant C. dubliniensis strain isolated from the South African samples was inhibited only by 5-flucytosine in vitro on the YO9 panel. Drug resistance among oral Candida species is common among African HIV patients in these 2 countries. Regional surveillance of Candida species drug susceptibility should be undertaken to ensure effective treatment for HIV-positive patients.

ESCMID* guideline for the diagnosis and management of Candida diseases 2012: patients with HIV infection or AIDS

Mucosal candidiasis is frequent in immunocompromised HIV-infected highly active antiretroviral (HAART) naive patients or those who have failed therapy. Mucosal candidiasis is a marker of progressive immune deficiency. Because of the frequently marked and prompt immune reconstitution induced by HAART, there is no recommendation for primary antifungal prophylaxis of mucosal candidiasis in the HIV setting in Europe, although it has been evidenced as effective in the pre-HAART era. Fluconazole remains the first line of therapy for both oropharyngeal candidiasis and oesophageal candidiasis and should be preferred to itraconazole oral solution (or capsules when not available) due to fewer side effects. For patients who still present with fluconazole-refractory mucosal candidiasis, oral treatment with any other azole should be preferred based on precise Candida species identification and susceptibility testing results in addition to the optimization of HAART when feasible. For vaginal candidiasis, topical therapy is preferred.

Frequent detection of 'azole' resistant Candida species among late presenting AIDS patients in northwest Ethiopia

BACKGROUND

The chronic use of antifungal agents in the treatment of fungal infection in general and oropharyngeal candidiasis mainly in AIDS patient's leads to the selection of strain resistant to these therapies and a shift in the spectrum of Candida species. This study determines the species diversity and in vitro susceptibility of Candida isolates from late presenting AIDS patients in northwest Ethiopia.

METHODS

Two hundred and twenty one HIV/AIDS patients were assessed with a standardized evaluation form at enrolment. Oral rinses were cultured on CHROMagar plates at 37°C for 48 hours and Candida species identification were made following standard microbiological techniques. In vitro drug susceptibility tests were made using broth microdilution method.

RESULTS

The colonization rate of Candida species was found to be 82.3% (177/215). C. albicans was the predominant species isolated from 139 (81%) patients but there was a diversity of other species. C. glabrata was the most frequent non-albicans species isolated in 22.5% (40/177) of the patients followed by C. tropicalis 14.1% (27/177), C. krusei 5.6% (10) and other unidentifiable Candida species 4% (7/177). Recurrent episodes of oropharyngeal candidiasis and previous exposure to antifungal drugs were found to be predisposing factors for colonization by non-albicans species. Irrespective of the Candida species identified 12.2% (11/90), 7.7% (7/90) and 4.7% (4) of the isolates were resistant to fluconazole, ketoconazole and itraconazole, respectively. In contrast, resistance to micafungin, amphotericin B and 5-Fluorocytosine was infrequent.

CONCLUSION

HIV/AIDS patients are orally colonized by single or multiple albicans and non- albicans Candida species that are frequently resistant to azoles and occasionally to amphotericin B, 5-Fluorocytosine and micafungin. These highlight the need for national surveillance for examining Candida epidemiology and resistance to antifungal drugs.

In vitro photodynamic inactivation of Candida species and mouse fibroblasts with phenothiazinium photosensitisers and red light

In the present study, the in vitro susceptibilities of five Candida spp. to photodynamic antimicrobial chemotherapy (PACT) with four phenothiazinium derivatives, methylene blue (MB), new methylene blue N (NMBN), toluidine blue O (TBO) and the novel pentacyclic phenothiazinium photosensitiser S137, in combination with red light were investigated. The efficacy of each PS was determined, initially, based on its minimal inhibitory concentration (MIC). Additionally, we evaluated the effect of the photodynamic treatment with NMBN and S137 on Candida survival and on the mouse fibroblast cell line L929. MICs varied both among PS and species and decreased with light dose increase. For most treatments (species and fluences) NMBN and S137 showed the lowest MICs. MICs for NMBN and S137 were <2.5 μM for all the Candida species when a fluence of 25 J cm⁻² was used. PACT with NMBN (fluence of 15 J cm⁻²) resulted in reductions in survival from 0.3 log (Candida krusei) to 3 logs (C. parapsilosis). PACT with S137 was more effective than with NMBN. Fluence of 15 J cm⁻² resulted in reductions in survival from 1 log (C. krusei) to 3 logs (C. parapsilosis) and fluence of 25 J cm⁻² resulted in a reduction of approximately 2 logs (C. krusei) and between 3 and 4 logs in survival of the other 4 species of Candida. In vitro relative toxicities of the phenothiazinium PS to mammalian cells exhibited a similar trend to the antifungal data, i.e. greater toxicity and phototoxicity with NMBN and S137 compared to the established PS.

Blue dye and red light, a dynamic combination for prophylaxis and treatment of cutaneous Candida albicans infections in mice

The objective of this study was to investigate photodynamic therapy (PDT), using blue dye and red light, for prophylaxis and treatment of cutaneous Candida albicans infections in mice. A mouse model of skin abrasion infected with C. albicans was developed by inoculating wounds measuring 1.2 cm by 1.2 cm with 10(6) or 10(7) CFU. The use of a luciferase-expressing strain of C. albicans allowed real-time monitoring of the extent of infection in mice noninvasively through bioluminescence imaging. The phenothiazinium salts toluidine blue O (TBO), methylene blue (MB), and new methylene blue (NMB) were compared as photosensitizers (PS) for the photodynamic inactivation of C. albicans in vitro. PDT in vivo was initiated either at 30 min or at 24 h after fungal inoculation to investigate the efficacies of PDT for both prophylaxis and treatment of infections. Light at 635 ± 15 nm or 660 ± 15 nm was delivered with a light dose of 78 J/cm(2) (for PDT at 30 min postinfection) or 120 J/cm(2) (for PDT at 24 h postinfection) in multiple exposures with bioluminescence imaging taking place after each exposure of light. In vitro studies showed that NMB was superior to TBO and MB as the PS in the photodynamic inactivation of C. albicans. The efficacy of PDT was related to the ratio of PS concentration to fungal cell density. PDT in vivo initiated either at 30 min or at 24 h postinfection significantly reduced C. albicans burden in the infected mouse skin abrasion wounds. These data suggest that PDT is a viable approach for prophylaxis and treatment of cutaneous C. albicans infections.

Investigation of mutations in Erg11 gene of fluconazole resistant Candida albicans isolates from Turkish hospitals

Widespread use of fluconazole has resulted in resistance in strains of Candida. The aim of our study was to investigate Y132H and other mutations in the ERG11 gene in conferring fluconazole resistance to C. albicans isolates. Seven fluconazole-resistant (R)/susceptible dose-dependent (SDD)/trailing and 10 fluconazole-susceptible (S) isolates were included. Restriction enzyme analysis was performed on all isolates for Y132H mutation and sequence analysis was performed for other mutations in the ERG11 gene. None of our strains had Y132H mutation. One single mutation (D153E, E266D, D116E, V437I) was detected in isolates 348, 533, 644, 1453, 2157, while the others had more than one nucleotide change. D116E and E266D, which were two mutations found in fluconazole R/SDD/trailing isolates with the highest frequency, were also detected in azole S strains. K143R, G464S, G465S and V488I mutations were determined in three of the R/SDD isolates. S412T and R469K mutations were detected only in this group of strains by sequence analysis. Mutations such as K143R, G464S, G465S, V488I, S412T and R469K in the ERG11 gene were determined to be effective mechanisms in our fluconazole R/SDD C. albicans isolates. Other mechanisms of resistance, such as overexpression of ERG11 and efflux pumps and mutations in the ERG3 gene should also be investigated.

Photodynamic therapy of bacterial and fungal biofilm infections

Biofilms have been found to be involved in a wide variety of microbial infections in the body, by one estimate 80% of all infections. Infectious processes in which biofilms have been implicated include common problems such as urinary tract infections, catheter infections, middle-ear infections, sinusitis, formation of dental plaque, gingivitis, coating contact lenses, endocarditis, infections in cystic fibrosis, and infections of permanent indwelling devices such as joint prostheses and heart valves. Bacteria living in a biofilm usually have significantly different properties from free-floating bacteria of the same species, as the dense and protected environment of the film allows them to cooperate and interact in various ways. One benefit of this environment is increased resistance to detergents and antibiotics, as the dense extracellular matrix and the outer layer of cells protect the interior of the community. In some cases antibiotic resistance can be increased 1000-fold. Also, the biofilm bacteria excrete toxins that reversibly block important processes such as translation and protecting the cell from bactericidal antibiotics that are ineffective against inactive targets. In the head and neck area, biofilms are a major etiologic factor in periodontitis, wound infections, oral candidiasis, and sinus and ear infections. For the past several decades, photodynamic treatment has been reported in the literature to be effective in eradicating various microorganisms using different photosensitizers, different wavelengths of light, and different light sources. PDT has been further studied to demonstrate its effectiveness for the eradication of both Gram-negative and Gram-positive antibiotic-resistant bacteria. This chapter will focus on the use of PDT in the treatment of antibiotic-resistant biofilms, antibiotic-resistant wound infections, and azole-resistant oral candidiasis using methylene blue-based photodynamic therapy.

Effect of amine fluoride-stannous fluoride preparations on oral yeasts in the elderly: a randomised placebo-controlled trial

OBJECTIVES

Oral yeast infections are an emerging problem among medically compromised and frail elderly. Antifungal drug resistance is also increasing because of an increase in non-albicans Candida strains in these populations. We therefore set out to study, in the randomised-controlled trial setting if the use of a topical amine fluoride-stannous fluoride combination (AmF-SnF2) could control oral Candida growth in the elderly. The hypothesis was based on earlier findings showing that in vitro this combination had antifungal efficacy.

METHODS

A total of 194 nursing home residents were randomised to receive either the test mouth rinse and toothpaste or a placebo twice daily for 8 months. Of these, 136 completed the trial. Saliva samples were taken using the oral rinse method, cultivated and the strain level identified with routine microbial methods. Compliance and use of preparations was assessed by a nurse.

RESULTS

Significantly at the end of the trial, less mucosal lesions were observed in the test group in comparison to controls. Total bacterial count decreased in both the groups during the trial. Candida albicans was the most prevalent strain detected both at baseline and 8 months later. Only a few subjects carried non-albicans strains. The AmF-SnF2 did not significantly affect mean oral Candida counts, but median Candida counts were reduced in the AmF-SnF2 group while an increase was seen in the placebo group. However, the differences observed were not statistically significant. Compliance among the regular elderly users slightly increased during the trial for both the groups.

CONCLUSION

The number of subjects with high Candida counts decreased in the AmF-SnF2 group. Hence, the fluoride combination might be useful as a support therapy for oral candidiasis. Prevalence of non-albicans Candida strains was low in this population.

Guidelines for the Prevention and Treatment of Opportunistic Infections among HIV-exposed and HIV-infected children: recommendations from CDC, the National Institutes of Health, the HIV Medicine Association of the Infectious Diseases Society of America, the Pediatric Infectious Diseases Society, and the American Academy of Pediatrics

This report updates and combines into one document earlier versions of guidelines for preventing and treating opportunistic infections (OIs) among HIV-exposed and HIV-infected children, last published in 2002 and 2004, respectively. These guidelines are intended for use by clinicians and other health-care workers providing medical care for HIV-exposed and HIV-infected children in the United States. The guidelines discuss opportunistic pathogens that occur in the United States and one that might be acquired during international travel (i.e., malaria). Topic areas covered for each OI include a brief description of the epidemiology, clinical presentation, and diagnosis of the OI in children; prevention of exposure; prevention of disease by chemoprophylaxis and/or vaccination; discontinuation of primary prophylaxis after immune reconstitution; treatment of disease; monitoring for adverse effects during treatment; management of treatment failure; prevention of disease recurrence; and discontinuation of secondary prophylaxis after immune reconstitution. A separate document about preventing and treating of OIs among HIV-infected adults and postpubertal adolescents (Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents) was prepared by a working group of adult HIV and infectious disease specialists. The guidelines were developed by a panel of specialists in pediatric HIV infection and infectious diseases (the Pediatric Opportunistic Infections Working Group) from the U.S. government and academic institutions. For each OI, a pediatric specialist with content-matter expertise reviewed the literature for new information since the last guidelines were published; they then proposed revised recommendations at a meeting at the National Institutes of Health (NIH) in June 2007. After these presentations and discussions, the guidelines underwent further revision, with review and approval by the Working Group, and final endorsement by NIH, CDC, the HIV Medicine Association (HIVMA) of the Infectious Diseases Society of America (IDSA), the Pediatric Infectious Disease Society (PIDS), and the American Academy of Pediatrics (AAP). The recommendations are rated by a letter that indicates the strength of the recommendation and a Roman numeral that indicates the quality of the evidence supporting the recommendation so readers can ascertain how best to apply the recommendations in their practice environments. An important mode of acquisition of OIs, as well as HIV infection among children, is from their infected mother; HIV-infected women coinfected with opportunistic pathogens might be more likely than women without HIV infection to transmit these infections to their infants. In addition, HIV-infected women or HIV-infected family members coinfected with certain opportunistic pathogens might be more likely to transmit these infections horizontally to their children, resulting in increased likelihood of primary acquisition of such infections in the young child. Therefore, infections with opportunistic pathogens might affect not just HIV-infected infants but also HIV-exposed but uninfected infants who become infected by the pathogen because of transmission from HIV-infected mothers or family members with coinfections. These guidelines for treating OIs in children therefore consider treatment of infections among all children, both HIV-infected and uninfected, born to HIV-infected women. Additionally, HIV infection is increasingly seen among adolescents with perinatal infection now surviving into their teens and among youth with behaviorally acquired HIV infection. Although guidelines for postpubertal adolescents can be found in the adult OI guidelines, drug pharmacokinetics and response to treatment may differ for younger prepubertal or pubertal adolescents. Therefore, these guidelines also apply to treatment of HIV-infected youth who have not yet completed pubertal development. Major changes in the guidelines include 1) greater emphasis on the importance of antiretroviral therapy for preventing and treating OIs, especially those OIs for which no specific therapy exists; 2) information about the diagnosis and management of immune reconstitution inflammatory syndromes; 3) information about managing antiretroviral therapy in children with OIs, including potential drug--drug interactions; 4) new guidance on diagnosing of HIV infection and presumptively excluding HIV infection in infants that affect the need for initiation of prophylaxis to prevent Pneumocystis jirovecii pneumonia (PCP) in neonates; 5) updated immunization recommendations for HIV-exposed and HIV-infected children, including hepatitis A, human papillomavirus, meningococcal, and rotavirus vaccines; 6) addition of sections on aspergillosis; bartonella; human herpes virus-6, -7, and -8; malaria; and progressive multifocal leukodystrophy (PML); and 7) new recommendations on discontinuation of OI prophylaxis after immune reconstitution in children. The report includes six tables pertinent to preventing and treating OIs in children and two figures describing immunization recommendations for children aged 0--6 years and 7--18 years. Because treatment of OIs is an evolving science, and availability of new agents or clinical data on existing agents might change therapeutic options and preferences, these recommendations will be periodically updated and will be available at http://AIDSInfo.nih.gov.

Species distribution and in vitro antifungal susceptibility of oral yeast isolates from Tanzanian HIV-infected patients with primary and recurrent oropharyngeal candidiasis

Background

In Tanzania, little is known on the species distribution and antifungal susceptibility profiles of yeast isolates from HIV-infected patients with primary and recurrent oropharyngeal candidiasis.

Methods

A total of 296 clinical oral yeasts were isolated from 292 HIV-infected patients with oropharyngeal candidiasis at the Muhimbili National Hospital, Dar es Salaam, Tanzania. Identification of the yeasts was performed using standard phenotypic methods. Antifungal susceptibility to fluconazole, itraconazole, miconazole, clotrimazole, amphotericin B and nystatin was assessed using a broth microdilution format according to the guidelines of the Clinical and Laboratory Standard Institute (CLSI; M27-A2).

Results

Candida albicans was the most frequently isolated species from 250 (84.5%) patients followed by C. glabrata from 20 (6.8%) patients, and C. krusei from 10 (3.4%) patients. There was no observed significant difference in species distribution between patients with primary and recurrent oropharyngeal candidiasis, but isolates cultured from patients previously treated were significantly less susceptible to the azole compounds compared to those cultured from antifungal naïve patients.

Conclusion

C. albicans was the most frequently isolated species from patients with oropharyngeal candidiasis. Oral yeast isolates from Tanzania had high level susceptibility to the antifungal agents tested. Recurrent oropharyngeal candidiasis and previous antifungal therapy significantly correlated with reduced susceptibility to azoles antifungal agents.

Genotyping and drug resistance profile of Candida spp. in recurrent and one-off vaginitis, and high association of non-albicans species with non-pregnant status

Recurrent vulvovaginal candidiasis affects women worldwide and the resistance to azole drugs may be an important factor. The extent of strain-to-strain variation within a species and its relationship to the ability of the organism to colonize the vulvovaginal mucosa is not well established. The aims of this study were to compare: (i) the genotypes of Candida strains in sequential infections in patients with recurrent vaginitis, (ii) the genotypes of strains in patients with only one episode of infection in a period of 1 year and (iii) determine the in vitro antifungal susceptibilities of strains that cause recurrent vaginitis. Fifty-one cultured specimens from six distinct Candida species were genotyped via random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) method using the ERIC1 and ERIC2 primers (ERIC, enterobacterial repetitive intergenic consensus). Statistical analyses allowed three different scenarios to be discerned for recurrent cases: (i) strain maintenance without genetic variation, (ii) strain maintenance with minor genetic variation and (iii) outright strain replacement. The genetic relatedness between strains from patients with recurrent vaginitis and patients with single episode of vaginitis were demonstrated by the dendogramme and the mean pairwise similarity coefficient S(AB) for the intergroup comparison was 0.223. However, intragroup genetic relatedness was slightly higher than intergroup comparison, with mean S(AB) of 0.261 and 0.331 for Groups I and II, respectively. A high proportion of Group I isolates (87.5%) causing recurrent infections were resistant to ketoconazole, whereas 41.7% of these isolates were cross-resistant to both clotrimazole and ketoconazole as shown by the in vitro antifungal susceptibility test, especially for C. glabrata isolates. Pregnancy status of patients displayed a highly significant association with C. albicans species whereas non-albicans species had a markedly higher prevalence in non-pregnant patients (p<0.001). These results may have a profound impact on the management of vaginal candidiasis, especially in recurrent cases.

Oral health and morbidity--implications of oral infections on the elderly

Detrimental effects of oral infections on general health have been known for almost 3000 years. Modern studies, however, have cast new light on the pathogenic mechanisms by which oral infections appear to link with morbidity and mortality. In particular, among the elderly, poor dental health seems to associate with all-cause mortality. This review aims to provide an overview of present knowledge of these issues, starting from dental bacteraemia, oral mucosal infections and problems of drug resistance and, briefly, discussing what is known about the link between oral health and some systemic diseases such as atherosclerosis and type-2 diabetes. The main conclusions are that scientific evidence is still weak on these interactions and that the elderly should be better taken into account when planning future studies. Functions of the body differ in the frail and diseased from those of the young. Consequently, novel prevention and treatment strategies should be developed and properly tested for combating oral infections in elderly populations. Specific suggestions for further research are outlined.

In vitro antifungal effect of amine fluoride-stannous fluoride combination on oral Candida species

OBJECTIVE

The combination of amine fluoride and stannous fluoride (AmF/SnF2) was, by chance, found to be antifungal in a clinical trial. This study investigated its effect on pathogenic Candida species with the hypothesis that the antifungal action on different species is variable.

MATERIALS AND METHODS

Growth inhibition effect of Meridol mouth rinse which contains 250 ppm AmF/SnF2 was evaluated on 43 reference and clinical strains of Candida albicans, C. dubliniensis, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis. Meridol base solution without AmF/SnF2 was used as a negative control.

RESULTS

Undiluted Meridolmouth rinse killed most study strains within a few minutes. In ascending order, C. parapsilosis, C. tropicalis, C. albicans, C. glabrata, C. krusei and C. dubliniensis showed higher resistance against AmF/SnF2 than C. guilliermondii.

CONCLUSION

AmF/SnF2 could be used as a potent adjunct to antifungal therapy for oral yeasts. Although different Candida species demonstrated variable sensitivity the most prevalent oral yeast C. albicans appeared sensitive to the AmF/SnF2 combination.

Increased expression and hotspot mutations of the multidrug efflux transporter, CDR1 in azole-resistant Candida albicans isolates from vaginitis patients

The aims of our research were to investigate the gene expression of the multidrug efflux transporter, CDR1 and the major drug facilitator superfamily transporter, MDR1 gene in azole drug-resistant Candida albicans and Candida glabrata clinical isolates recovered from vaginitis patients; and to identify hotspot mutations that may be present in the C. albicans CaCDR1 gene that could be associated with drug-resistance. The relative expression of the CDR1 and MDR1 transcripts in ketoconazole and clotrimazole-resistant isolates and drug-susceptible ATCC strains were determined by semi-quantitative reverse transcription-polymerase chain reaction. Expression of CaCDR1 transcript was upregulated to varying extents in all three azole-resistant C. albicans isolates studied (1.6-, 3.7- and 3.9-fold) and all three C. glabrata isolates tested (at 1.9-, 2.3- and 2.7-fold). The overexpression level of CaCDR1 in the isolates correlated with the degree of resistance as reflected by the minimum inhibitory concentration (MIC) of the drugs. The messenger RNA for another efflux pump, MDR1, was also overexpressed in one of the azole-resistant C. albicans isolates that overexpressed CDR1. This finding suggests that drug-resistance may involve synergy between energy-dependent drug efflux pumps CDR1p and MDR1p in some but not all isolates. Interestingly, DNA sequence analysis of the promoter region of the CaCDR1 gene revealed several point mutations in the resistant clinical isolates compared to the susceptible isolates at 39, 49 and 151 nucleotides upstream from the ATG start codon. This finding provides new information on point mutations in the promoter region which may be responsible for the overexpression of CDR1 in drug-resistant isolates.

Antifungal agents of use in animal health--chemical, biochemical and pharmacological aspects

A limited number of antifungal agents is licensed for use in animals, however, many of those available for the treatment of mycoses in humans are used by veterinary practitioners. This review includes chemical aspects, spectra of activity, mechanisms of action and resistance, adverse reactions and drug interactions of the antifungals in current use.

Antifungal drug resistance

The increasing incidence of invasive fungal infections is the result of many factors, including an increasing number of patients with severe immunosuppression. Although new drugs have been introduced to combat this problem, the development of resistance to antifungal drugs has become increasingly apparent, especially in patients who require long-term treatment or who are receiving antifungal prophylaxis, and there is growing awareness of shifts of flora to more-resistant species. The frequency, interpretation, and, in particular, mechanism of resistance to current classes of antifungal agents, particularly the azoles (where resistance has climbed most prominently) are discussed in this review.

Resistance mechanisms in clinical isolates of Candida albicans

Resistance to azole antifungals continues to be a significant problem in the common fungal pathogen Candida albicans. Many of the molecular mechanisms of resistance have been defined with matched sets of susceptible and resistant clinical isolates from the same strain. Mechanisms that have been identified include alterations in the gene encoding the target enzyme ERG11 or overexpression of efflux pump genes including CDR1, CDR2, and MDR1. In the present study, a collection of unmatched clinical isolates of C. albicans was analyzed for the known molecular mechanisms of resistance by standard methods. The collection was assembled so that approximately half of the isolates were resistant to azole drugs. Extensive cross-resistance was observed for fluconazole, clotrimazole, itraconazole, and ketoconazole. Northern blotting analyses indicated that overexpression of CDR1 and CDR2 correlates with resistance, suggesting that the two genes may be coregulated. MDR1 overexpression was observed infrequently in some resistant isolates. Overexpression of FLU1, an efflux pump gene related to MDR1, did not correlate with resistance, nor did overexpression of ERG11. Limited analysis of the ERG11 gene sequence identified several point mutations in resistant isolates; these mutations have been described previously. Two of the most common point mutations in ERG11 associated with resistance, D116E and E266D, were tested by restriction fragment length polymorphism analysis of the isolates from this collection. The results indicated that the two mutations occur frequently in different isolates of C. albicans and are not reliably associated with resistance. These analyses emphasize the diversity of mechanisms that result in a phenotype of azole resistance. They suggest that the resistance mechanisms identified in matched sets of susceptible and resistant isolates are not sufficient to explain resistance in a collection of unmatched clinical isolates and that additional mechanisms have yet to be discovered.

Esophageal candidiasis in human immunodeficiency virus-infected pediatric patients after the introduction of highly active antiretroviral therapy

OBJECTIVE

To investigate epidemiologic trends, clinical features and outcome of esophageal candidiasis in the era of highly active antiretroviral therapy in a prospectively monitored population of HIV-infected children and adolescents followed at the National Cancer Institute.

PATIENTS AND METHODS

The records of all HIV-infected pediatric patients (n = 266) followed between 1995 and 2000 were reviewed for a history of esophageal candidiasis. Proven esophageal candidiasis was defined as clinical plus radiographic and/or endoscopic findings of esophageal candidiasis. Probable esophageal candidiasis was defined as esophageal symptoms that responded promptly to appropriate antifungal therapy. The medical records of all patients fulfilling these criteria were reviewed for demographic, clinical and laboratory features at presentation, as well as therapeutic interventions and outcome.

RESULTS

Of the 266 patients 9 (3.4%) had 18 documented episodes of proven (n = 16) or probable (n = 2) esophageal candidiasis. A history of prior mucosal candidiasis was present in 94% of all episodes. The median CD4+ count at the time of diagnosis was 7/microl (range, 0 to 550), and the median viral load was 98000 copies/ml (range, 22916 to 1278933). Concurrent oropharyngeal candidiasis was the most common clinical presentation (72%) followed by fever (55%), odynophagia (50%) and nausea or vomiting (39%). Treatment consisted of antifungal triazoles (61%) or amphotericin B (39%). Clinical cure was achieved in 15 cases, including all patients receiving triazoles.

CONCLUSION

Esophageal candidiasis persists in the subgroup of patients not responding to highly active antiretroviral therapy and in that setting may present without concomitant oropharyngeal candidiasis or typical clinical symptoms, thus underscoring the need for a high index of suspicion in children with very low CD4+ counts.