Prophylaxis of candidiasis in patients with leukemia and bone marrow transplants

ObjectivesThe increased risk for systemic fungal infection and the potential fatal consequences of disseminated candidiasis in bone marrow transplant patients has prompted study of prophylaxis and early treatment of candida colonization and infection.Study designPatients with leukemia who received fluconazole prophylaxis were compared with a concurrent group ofpatients not given prophylaxis for fungal organisms.ResultsA trend to reduction of oropharyngeal colonization by Candida albicans was seen (p=0.07) although no significant differences in systemic candidiasis were seen. In patients with documented systemic candidiasis, oral colonization was present and systemic infection was identified after the development of ulcerative oral mucositis.ConclusionsOur results support the potential of fluconazole to reduce oropharyngeal colonization caused by Candida albicans, however, we did not show prophylaxis of oral candidiasis or systemic candidiasis. These findings and reports of fluconazole-resistant candidal species and a rising number of cases of infection as a result of Candida krusei indicate the need for further studies of prophylaxis of candidal infection in patients who are anticipated to develop profound neutropenia.     

Effect of oral antiseptic agents on phospholipase and proteinase enzymes of Candida albicans

ObjectiveCandida-associated denture stomatitis is the most prevalent form of oral candida infections among the denture wearers. Generally, antiseptic oral rinses used in the treatment of these infections are considered as an adjunct or alternative antifungal treatment. Studies have suggested that the intraoral concentrations of antiseptics decrease substantially to the sub-therapeutic levels on account of the dynamics of the oral cavity. This condition yields the question about the minimum antiseptic concentration that effect the character or pathogenesis of Candida during treatment. The extracellular phospholipase and proteinase enzymes of Candida albicans are regarded to have a crucial role in the pathogenesis of human fungal infections. Therefore, the aim of this study was to investigate the effect of different sub-therapeutic concentrations of chlorhexidine gluconate, hexetidine and triclosan on the production of these enzymes by C. albicans strains isolated from 20 patients with denture stomatitis.MethodsPhospholipase test was done by using Sabouraud dextrose agar with egg yolk, proteinase test was done by using bovine serum albumin agar.MethodsPhospholipase test was done by using Sabouraud dextrose agar with egg yolk, proteinase test was done by using bovine serum albumin agar.ResultsExoenzyme production of 20 strains which were brief exposured to sub-therapeutic concentrations of three antiseptic agents decreased significantly compared with the strains that were not exposured with antiseptic values (p < 0.05). There was significant difference between the sub-therapeutic concentrations of each of three antiseptics (p < 0.05). When the same concentrations of each antiseptic was compared, there were no significant differences between enzymatic activities (p > 0.05).ConclusionsThe results of this study show that sub-therapeutic levels of each antiseptic may modulate candidal exoenzyme production, consequently suppressing pathogenicity of C. albicans.     

Correlation between enzyme production,germ tube formation and susceptibility to fluconazole in Candida species isolated from patients with denture‐related stomatitis and control individuals

Introduction: Phospholipase and proteinase secretion in yeasts of the genus Candida has been described as a relevant virulence factor. Also, germ tube formation by Candida albicans is associated with its invasive capacity and is considered an important pathogenic mechanism. Methods: To link the production of hydrolytic enzymes with the capacity to produce infection, 232 clinical isolates of yeasts from the oral cavity of 140 individuals wearing removable maxillary protheses were studied. The sample was composed of 70 patients with denture‐related stomatitis (DRS) and 70 individuals with normal palatal mucosa. For strains identified as C. albicans, the correlation between germ tube formation and their capacity to cause infection was studied and the presence of Candida dubliniensis was investigated. Susceptibility to fluconazole was evaluated. Results: Candida albicans was the only species producing phospholipase and germ tube. We observed a higher level of production of phospholipase in cases of infection compared with commensals. Significant differences between the two groups of C. albicans isolates were observed as to germ tube production. Only, Candida glabrata showed lower susceptibility to fluconazole. Conclusion: The results reinforced the idea that C. albicans is the most frequent and can be the most pathogenic yeast in oral candidosis. However, the strains isolated from DRS patients and healthy individuals showed the same virulence factors. It seems that several virulence attributes are involved in the infective process but no single factor contributes to Candida virulence. Candida dubliniensis was absent in the oral cavity of individuals with and without DRS.     

A randomised crossover trial to compare the potential of stannous fluoride and essential oil mouth rinses to induce tooth and tongue staining

This study compared the staining potential of two experimental amine fluoride/stannous fluoride mouth rinses (A and B), a phenolic/essential oil rinse (C) and a negative control, water, rinse (D). The study was a single centre, randomized, single-blind, four treatment crossover study design among healthy participants. Prior to each study period, participants received a dental prophylaxis. On the Monday of each period, subjects suspended oral hygiene, and under supervision, rinsed with the allocated mouth rinse immediately followed by a warm black tea solution at hourly intervals eight times a day for 4?days. On Friday, the area and intensity of staining on the teeth, the primary outcome measure and dorsum of tongue were assessed. This regimen was repeated for all the three subsequent treatment periods. Rinse B produced less stain than rinse A, but the difference was not significant (p?=?0.20). Rinse B produced significantly more stain than rinse C (p?<?0.05) and D (p?<?0.001). For tongue staining, rinse B produced significantly more staining than D (p?<?0.01) but not A or C. Overall, all test rinses produced more staining than placebo with an overall pattern for more staining with stannous formulations. Individuals using stannous or phenolic/essential oil mouth rinse formulations should be advised of the possible staining side effect and that this can be easily removed by a professional dental cleaning.     

Fluconazole resistant oral candidiasis in HIV-infected patients

OBJECTIVE: To evaluate the risk factors associated with the emergence of fluconazole resistant Candida spp. in HIV-infected patients with oral candidiasis. METHODS: Candida spp. were isolated from oral swabs and tested in vitro for resistance to fluconazole. The factors potentially correlated with vazole-resistent Candida spp. infections were investigated. RESULTS: Fifty-one out of 118 patients (43%) with oral candidiasis had fluconazole resistant Candida spp. The following factors were significantly associated with the development of fluconazole resistance: (1) more than five episodes of oral candidiasis in the previous year (P < 0.001); (2) fluconazole therapy in the previous 6 months (P < 0.001); (3) C3 category of HIV infection (P< 0.001); and (4) low number of TCD4⁺ cells (<50 mm³, P = 0.002). According to multivariate analysis, previous therapy with fluconazole was the only risk factor that independently influenced the development of Candida spp. resistance (P = 0.003). CONCLUSIONS: The prophylaxis and therapy of mild fungal infections in HIV-infected patients, which may lead to azole resistance, should be carefully considered.     

The effect of subinhibitory concentrations of gentian violet on the germ tube formation by Candida albicans and its adherence to oral epithelial cells

ObjectiveThis study investigated the effect of subinhibitory concentrations of gentian violet on the germ tube formation by Candida albicans and its adherence ability to oral epithelial cells.MethodsThirty strains of C. albicans isolated from denture wearers, normal healthy individuals and HIV positive patients were used in the study. The antifungal property (Minimum Fungicidal Concentration) of gentian violet was determined at various time intervals using a microdilution technique. The effect of subinhibitory concentrations of gentian violet on the adherence ability (0.000244%) and on germ tube formation ((0.000244%, 0.000122%, 0.000061% and 0.000031%) was determined. In both experiments, water was used as a control. The test results were compared using the Kruskal-Wallis test.ResultsAt 60 min a high concentration (0.0078%) of gentian violet was required to completely kill C. albicans. Subinhibitory concentrations of gentian violet significantly reduced the adherence ability of C. albicans by 57% (p < 0.01) and equally inhibited germ tube formation (p < 0.01) compared with the controls. The inhibition was concentration dependent, with up to 98% reduction at a concentration of 0.000244%. Germ tube reduction was significantly higher in the isolates from the HIV positive patients than in the isolates from denture wearers.ConclusionAt high concentrations, gentian violet killed C. albicans, whereas at subinhibitory concentrations it reduced its virulence by preventing the adherence ability and germ tube formation. This suggests that the beneficial effects of gentian violet would last beyond the fungicidal concentrations in the treatment of candidiasis.     

Natural history of Candida species and yeasts in the oral cavities of infants

A longitudinal study was made of the presence of Candida species and yeasts in infants from the day of birth until 1-yr-old, diagnosed by the culture of oral swab samples. The isolation rate of Candida rose from 5.7 per cent neonatally to 14.2 per cent on discharge from hospital at 7 days. The prevalence increased sharply when the infants returned home, reaching 82 per cent at 4 weeks of age, but then slowly declined to 50 per cent at 1 yr. At 4 weeks, yeasts were isolated from an additional 14 per cent of infants. The predominant species was C. albicans with relatively few isolates of C. tropicalis, C. parapsilosis and C. pseudotropicalis. Estimates of neonatal serum antibody to C. albicans showed no correlation with initial or subsequent oral colonization by this organism.     

Antiadherent activity of Schinus terebinthifolius and Croton urucurana extracts on in vitro biofilm formation of Candida albicans and Streptococcus mutans

Objective

To evaluate the antiadherent property of crude, methanol and acetate methanol extract fractions from Schinus terebinthifolius and Croton urucurana in hydroalcoholic (HA) and dimethylsulfoxide (DMSO) solvents on in vitro biofilms formed by Streptococcus mutans and Candida albicans strains.

Design

The minimal concentration of adherence (MICA) was determined to evaluate the antiadherent potential of extracts on the in vitro biofilm formation. The extracts of plants were subjected to thin layer chromatography (TLC) in order to detect what class of compounds was responsible for the antiadherent activity. Data were estimated by analysis of variance (ANOVA) complemented by Tukey test level of significance set at 5%.

Results

Both plants demonstrated inhibition of S. mutans and C. albicans on in vitro biofilm formation. The biofilms of C. albicans were more efficiently inhibited by the S. terebinthifolius fraction of acetate–methanol and methanol in hydroalcoholic solvents (p < 0.05). The S. mutans biofilms adherence was best inhibited by the S. terebinthifolius crude extract and its methanolic fraction, both in hydroalcoholic solvent (p < 0.05). TLC of crude extracts and fractions of S. terebinthifolius detected the presence of several active compounds, including phenolic compounds, anthraquinones, terpenoids, and alkaloids. C. urucurana extracts confirmed activity for both microorganisms (p < 0.05). However, higher concentrations were needed to achieve antiadherent activity, mainly to inhibit in vitro biofilm formation of C. albicans.

Conclusion

The antiadherent potential of both plants on in vitro biofilms formed by C. albicans and S. mutans were confirmed, suggesting the importance of studies about these extracts for therapeutic prevention of oral diseases associated with oral biofilms.     

Clinical aspects related to endodontic yeast infections

Yeasts can be detected in 7–18% of infected root canals. They are commonly associated with persistent cases of apical periodontitis, but yeasts can also be isolated in primary apical periodontitis. Their relative proportion of the root canal flora is low, usually below 1%. Therefore, yeast detection with conventional microbiological methods may be difficult. Selective culture media such as Sabouraud dextrose agar combined with cultivation from undiluted sample should be used for primary isolation of yeasts in endodontic infections. Preliminary identification of yeasts is based on typical colony and cellular morphology and a positive catalase test. Detection by molecular biological methods is sensitive, but may occasionally also give false‐positive results. Candida albicans is the most commonly detected yeast species from infected root canals. It is typically found together with Gram‐positive bacteria such as streptococci, but can also be isolated in pure culture, which is an indication of its pathogenicity. A variety of virulence factors enable C. albicans to adhere to and penetrate into dentine. Furthermore, C. albicans tolerates harsh ecological conditions including high alkalinity. Calcium hydroxide is generally not efficient against oral yeasts in vitro; the in vivo effectiveness of calcium hydroxide is not known. However, sodium hypochlorite, iodine compounds, and chlorhexidine have proven effective against yeasts both in experimental conditions as well as in vivo and may offer effective treatment possibilities against endodontic yeast infections.     

Presence of Candida spp. in the oral cavity of heart transplantation patients

Candida spp. can lead to infections or even fungal sepsis particularly among immunocompromized individuals.

Objective

The aim of the present study was to analyze the presence of Candida spp. among patients subjected to orthotopic heart transplantation.

Material and Methods

Oral rinses from 50 patients subjected to orthotopic heart transplantation, aged 13 to 70 years, 40 males and 10 females, were examined. Sexage-oral conditions matched-control included 50 individuals who were not subjected to any kind of transplantation and were not immunocompromized for any other reason. Counts of yeasts were expressed as median values of logarithm of cfu/mL and were statistically compared by Mann-Whitney’s test. The heart transplant and control groups were compared for the presence of Candida spp. by chi-square test (p<0.05).

Results

The results showed statistically significant difference (p=0.001) in the prevalence of Candida spp. between the transplantation and control groups. Counts of yeasts (cfu/mL) in the transplanted group were significantly higher than in the control group (p=0.005). Candida albicans was the most prevalent species isolated from both groups.

Conclusion

It was concluded that Candida yeast counts were higher in the heart transplant recipients than in the controls. There was higher variation of Candida species among the heart transplant patients and the most frequently isolated samples were: Candida albicans, Candida glabrata and Candida tropicalis. Isolates of Candida dubliniensis was not found in either of the groups.     

High through-put sequencing analysis of changes in oral flora in rats before and after zoledronate administration

The aim of this study was to compare the changes in the oral flora of Sprague-Dawley rats before intraperitoneal injection of zoledronic acid, 6 weeks and 12 weeks after injection. Clinically, some antibiotics effectively treat patients with medicine-related osteonecrosis of the jaws (MRONJ), but the effect of broad-spectrum antibiotics for osteomyelitis of the jaw is not obvious. We therefore speculated that MRONJ may have some dominant bacteria. We used 12 healthy rats for the experiment. One rat was used for haematoxylin and eosin staining, three were used for gene analysis, three for signal molecule research, and five for 16SrDNA high-pass sequencing to compare the changes of flora before intraperitoneal injection of zoledronic acid, and 6 and 12 weeks after injection once every three days. Alpha and beta analysis was used for sequencing data. Analysis of the flora showed that the alpha diversity of the bacteria of rats injected with zoledronic acid was significantly higher than it was before injection (p < 0.05). At the phylum level, Bacteroidetes at 6 and 12 weeks of injection were significantly higher than those before injection (p < 0.05). At the genus level, the proportions of Novophingobium, Dubosiella, Mannheimia, Prevotella, Brevundimonas, and Bacteroides were higher than they were before injection (p < 0.05). The proportions of Lactobacillus, Mannheimia, Brevundimonas, Bacteroides, Roseovarius, Salegentibacter, Marinobacter, and Granulicatella in rats injected for 12 weeks were higher than those before injection (p < 0.05). Zoledronic acid can change the structure of oral flora in SD rats, in which Bacteroides increased and Actinomycetes decreased.     

Oral carriage of yeasts, coliforms and staphylococci in patients with advanced malignant disease

Many patients with advanced cancer have oral problems, some of which may have a microbiologic basis. The oral flora in such patients has not, however, been characterized. This study has assessed the prevalence of yeasts, coliforms and coagulase positive staphylococci in the oral flora of 197 patients with advanced cancer. Both imprint cultures (n = 197) and oral rinses (n = 161) were collected. Yeasts were isolated from the mouths of 83% of the patients, coliforms from 49.1% and coagulase-positive staphylococci from 28%. All these percentages are considerably in excess of reported levels for healthy individuals. The results indicate a loss of colonization resistance of the oral mucosa in terminal cancer, with potential implications for the development of mouth care regimes for such patients.     

Oral microbial colonization in children with sickle cell anaemia under long-term prophylaxis with penicillin

Background and objective

Sickle cell anaemia (SCA) is the most frequent haematological hereditary disease. Children with SCA are submitted to long-term prophylactic therapy with penicillin, but little is known about its impact on oral microflora. The aim of this study was to evaluate the oral microbial colonization of paediatric patients with SCA.

Design

Forty children (4–11 yrs old) with SCA (genotype SS) under long-term prophylactic treatment with penicillin were included in the study. Age/gender-matched control group of healthy children was also included. Scores of dmft/DMFT (number of decayed (D), missing (M), or filled (F) teeth; dmft, for primary dentition; DMFT, for permanent dentition) were obtained and stimulated saliva was sampled. Salivary flow rate and buffering capacity were evaluated. Counts of microorganisms (mutans streptococci, lactobacilli and yeasts) were determined by plating method. Yeasts were identified by API 20C AUX and PCR.

Results

Mean dmft/DMFT values were similar in the studied groups (SCA 2.13/1.60 and control 2.38/1.3). Although no significant differences between cariogenic microorganism counts were observed, significantly higher yeasts oral levels were observed in SCA group. Controls showed lower salivary buffering capacity. Candida albicans was the most frequently isolated species in both groups. Candida famata, Candida parapsilosis and Candida tropicalis were also isolated from controls. Candida dubliniensis, Candida rugosa and Candida sphaerica were found only in SCA group.

Conclusions

Based on the results, it could be concluded that paediatric patients with SCA showed significantly higher oral level of yeasts. Uncommon fungal species were found in SCA group. Similar caries prevalence and counts of lactobacilli and streptococci in relation to controls were observed.     

Identification of Candida dubliniensis among oral yeast isolates from an Italian population of human immunodeficiency virus‐infected (HIV+) subjects

Candida dubliniensis, an emerging oral pathogen, phenotypically resembles Candida albicans so closely that it is easily misidentified as such. The aim of the present study was to evaluate the usefulness of two phenotypic methods, growth at 45°C and 2,3,5‐triphenyltetrazolium chloride (TTC) reduction, for confirming presumptive identification of C. dubliniensis and C. albicans by colony color on CHROMagar Candida (CAC) medium. A combination of these methods was used to establish the prevalence of oral C. dubliniensis in an Italian population of 45 human immunodeficiency virus (HIV)‐infected subjects. Twenty‐two samples (48.9%) were positive for yeasts on CAC medium producing a total of 37 fungal isolates. The colony color and 45°C growth ability test correctly identified all C. dubliniensis and C. albicans isolates (5/37, 13.5%, and 16/37, 43.2%, respectively), while assessment of TTC reduction misidentified one C. albicans isolate. The isolation rate of C. dubliniensis was 11.1% (5/45 patients). All of the C. dubliniensis isolates were highly susceptible to fluconazole (MIC = 0.5 µg/ml). The combination of CAC medium screening with growth at 45°C and TTC reduction tests may represent a simple, reliable and inexpensive identification protocol for C. dubliniensis.     

Structure Study of Amalgam III. The Marginal Structure of Class II Amalgam Fillings

Oral leukoplakias, particularly non-homogenous types, are often invaded by yeasts, with Candida albicans being the dominant species. The more advanced precancerous leukoplakia lesions yield more rarely occurring biotypes of C. albicans, suggesting a causal role for these biotypes in the malignant transformation. N-nitroso-benzylmethylamine (NBMA) is a compound able to induce carcinoma of the esophagus and the oral cavity in the rat. The catalytic potential of yeasts, isolated from leukoplakia lesions and from normal mucosa, to produce NBMA from the precursors N-benzyl-methylamine and nitrite was assessed at pH 6.8. The yeast strains differed in nitrosation potential, ranking from 0 to 1.2 μg NBMA/10⁶ cells. C. albicans strains of the more rarely occurring biotypes showed the highest nitrosation potential, whereas C. tropicalis, C. parapsilosis, and Torulopsis glabrata were ranked lower. Strains with high nitrosation potential were generally isolated from lesions with more advanced precancerous changes. Thus, further evidence is provided supporting the hypothesis that yeasts play a causal role in oral cancer by means of endogenous nitrosamine production.     

Stable azole drug resistance associated with a substrain of Candida albicans from an HIV-infected patient

Oral candidiasis is one of the earliest and most frequent complications of a failing immune system in HIV-infected individuals. For several years, oral candidiasis has been treated effectively with azole drugs, the one most frequently used is fluconazole. Unfortunately, extensive use of the drug for treatment and prophylaxis has led to treatment failure in an increasing number of patients. In most of these cases, strains of C. albicans isolated from the infection are less susceptible to fluconazole. The development of azole resistance in strains of C. albicans has been studied biochemically and more recently with molecular techniques. One excellent example of the development of azole resistance in C. albicans has been documented in a series of 17 C. albicans isolates from a single patient over a 2-year period. During this time, the patient experienced 14 episodes of oral candidiasis and was treated with increasing doses of fluconazole. Molecular and biochemical analyses confirms that the isolates are the same strain of C. albicans and that the resistance in these isolates is stable over 600 generations, suggesting that the changes in this strain are genetic in nature. In addition, the development of resistance is correlated with the identification of a substrain or variant of the original strain, as identified by restriction fragment length polymorphism (RFLP) analysis with the moderately repetitive probe, Ca3. The analysis of this series of isolates demonstrates that azole drug resistance is associated with several small genetic changes, each of which contributes to the overall resistance of the strain. Clearly, continual use of azole drugs by a patient can select for genetic changes that render oral candidiasis refractory to treatment.     

Quantitative interactions between Candida albicans and the mutans streptococci in patients with Down Syndrome

Background Oral microorganisms produce damage through the transfer to bloodstream, colonizing other tissues or direct damage in the oral cavity. Aim to study the quantitative interactions between C. albicans and the mutans streptococci and ms serotypes in the saliva of the oral cavity of patients with Down syndrome (DS). Material and Methods Included 120 patients of both genders, 60 patients with Down syndrome (DS) and 60 patients as a control group (CG). Samples of saliva were taken, and bacteria and fungi were grown on TYCSB and Saboureaud agar. Microbiological, serological and quantitative analyses were performed to determine the kind of isolated of microorganisms corresponding to the ms c, e, f and k for species S. mutans and d and g for S. sobrinus and C. albicans. Electronic scanning microscopy was employed to visualize and confirm the colonies under study. Statistics analysis included t-test proofs for matched data test, Scheffé and ANOVA. Results Forming units (CFU) per mL of saliva of C. albicans a significant difference was observed among DS>CG groups. A correlation of the C. albicans quantity and the ms count was found by age intervals however, tendencies were different in SD and CG. Also, the CFU of C. albicans was different among the serotypes of ms (c, e, f, k <d, g, h, <notyped). Conclusions These results show a significant non-random association between these two commensal microorganisms in different patient groups. Key words:Down Syndrome, Candida albicans, microorganism interactions, mutans streptococci and oral cavity.     

Diversity,frequency and antifungal resistance of Candida species in patients with type 2 diabetes mellitus

Objective: To determine number, species of Candida and Candida resistance to antifungal therapy according to the metabolic control state and the associated salivary changes in patients with type 2 diabetes mellitus (DM2).

Materials and methods: Samples of non-stimulated saliva were collected from 52 patients with DM2. Salivary pH was measured and cultured on Sabouraud glucose agar and the values of CFU/ml were calculated. The species were presumptively identified using CHROMagar Candida^® plates, and identification was confirmed by polymerase chain reaction (PCR). C. albicans isolates were cultured on SGA tetracycline agar with nystatin and fluconazole diffusion disks to measure susceptibility.

Results: Sixty six percent of the yeasts isolated were Candida albicans, followed by C. glabrata (20.7%). In patients with decompensated DM2, there was an inverse association between HbA1c value and salivary pH. At higher levels of salivary acidification, a greater diversity and quantity of yeasts of the genus Candida were observed. With nystatin, higher inhibition was observed at lower pH.

Conclusions: The antifungal therapies could be more effective if it consider, qualitative salivary characteristics as pH, that could determine the susceptibility of species of Candida to at least to nystatin, which is the most used antifungal for treatment to oral candidiasis in patients with DM2.     

Prevalence of fluconazole-resistant strains of Candida albicans in otherwise healthy outpatients

BACKGROUND: In contrast to the immunosuppressed patient population, the prevalence of fluconazole-resistant strains of Candida albicans among healthy individuals has not been extensively studied. METHODS: Candida species were cultured form 50 healthy outpatients with clinical signs of oral candidiasis. Following one week of the recommended fluconazole regimen, post-treatment cultures were obtained. Both pre- and post-treatment yeasts were identified and in vitro susceptibility testing was performed using the NCCLS M-27A method. Strains were further differentiated using established cDNA probes. RESULTS: Forty-four patients (88%) had positive C.albicans cultures prior to treatment. Antifungal susceptibility testing of these strains demonstrated no in vitro resistance to fluconazole. At post-treatment evaluation, eight patients (18%) had persistent signs of infection and 10 patients (23%) had positive Candida sp. cultures despite no clinical signs of infection. DNA analysis confirmed that the same C. albicans strain was present both in the pre-treatment and the post-treatment cultures. CONCLUSIONS: Our results showed that the presence of fluconazole-resistant strains of C.albicans does not appear to be prevalent among healthy outpatients furthermore, in vitro antifungal susceptibility testing does not always predict successful therapy in these patients.