Enhanced susceptibility of Candida albicans to chlorhexidine under anoxia

Aim: Periodontal pockets can be colonized not only by bacteria, but also by Candida albicans. However, its role in periodontitis is unknown. This study evaluated the inhibitory performance of chlorhexidine digluconate under normoxic and anoxic conditions against 16 strains of C. albicans from periodontal pockets and other 20 from the oral mucosa. Methods: Strains were grown in normoxia and anoxia to adapt themselves to the different atmospheric conditions. Microdilution-based assays were carried out to determine the minimum concentrations of chlorhexidine that may restrain the conditioned candidal strains, in normoxia (normoxic MIC) and anoxia (anoxic MIC). The Mann-Whitney U test was used to evaluate the antimicrobial effect of chlorhexidine on C. albicans under normoxic and anoxic conditions (α = 0.05). Results: The normoxic MIC of chlorhexidine varied broadly from 150 to 1200 μg/mL, whereas its anoxic MIC varied narrower from 2.34 to 37.5 μg/mL. Regarding the origins of strains, no statistically significant differences (p > 0.05) were found. Conclusions: These results indicate that anoxic environmental conditions, compatible with periodontal pockets, tend to enhance C. albicans susceptibility to chlorhexidine.published_or_final_versio

Clonal variability among oral Candida albicans assessed by allozyme electrophoresis analysis

A total of 49 Candida albicans strains were isolated from the saliva of 11 healthy children in Piracicaba, Brazil and were analyzed according to their alloenzymatic patterns. Among eight loci assayed, seven were polymorphic and allowed to determine allelic and genotype frequencies, in order to establish the genetic Variables for this fungal population. Some children showed just one genetic type, whereas other harbored two or mon clones of such yeast, in a multiclonal manner of colonization by C. albicans.15635035

Anaerobic enhancement of protease secretion by periodontal Candida albicans strains

Session - Candida albicans: abstract no. 1728OBJECTIVES: This study evaluated the secretion patterns of aspartyl-protease (Sap) by periodontal and non-periodontal Candida albicans strains in normoxic and anoxic conditions. METHODS: Ten non-related periodontal and other ten non-periodontal C. albicans strains were planktonically grown under normoxic and anoxic conditions in protease-inducible broth. Sap activities were quantified in supernatants using azoalbumin as substrate. One unit of Sap activity was defined as the amount of enzyme necessary to increase in 0.001 unit of OD440nm per min of digestion. Protein concentrations of supernatants were spectrophotometrically determined by Coomassie blue method, with BSA as standard. The number of units of Sap activity per milligram of protein was taken as the specific enzymatic activity. RESULTS: All candidal strains, independent from their origin or atmospheric environment, secreted Saps. Non-parametric multiple comparisons among the four subgroups revealed that in anoxic conditions periodontal strains tend to secret significant higher amounts of Sap than in normoxic conditions (p < 0.0001). However, this superior secretion rate is not different from those obtained for non-periodontal strains grown in normoxic or anoxic conditions. CONCLUSION: There is a possibility of adaptation or selection of C. albicans strains by the periodontal microenvironment. This study was supported by grants supplied by Araucaria Foundation (Process 9042), Coordination for the Improvement of Higher Education Personnel (CAPES Process BEX 0559/06-7), and intramural funds from OBU-PPDH-HKU.link_to_OA_fulltextThe 89th General Session and Exhibition of IADR/AADR/CADR, San Diego, CA., 16-19 March 2011

Numerical analysis variations of SDS-page protein patterns using different culture media for the cultivation of Candida from the oral cavity

The relationships among 12 oral yeast strains belonging to 5 yeast species were determined by one-dimensional electrophoresis of SDS-solubilized whole-cell proteins using different culture medium in the cultivation of the cells. The phenograms were made using Simple Matching coefficient (SM) and UPGMA clustering method. The strains investigated represented species from the genus Candida, species C. albicans, C. tropicalis, C. guilliermondii, C. parapsilosis, and C. krusei, all isolated from the oral cavity of normal and healthy people. The data obtained from the phenograms showed a high difference in protein patterns when all the species were compared using different culture media, suggesting that different. nutritional compositions led to the expression of different proteins derived from alternatives metabolic pathways expressed by the electrophoretic profiles. When looking to the different phenograms most species are not delineated as separate entities. A considerable protein electrophoretic heterogeneity is observed among strains of single species. From the data presented it seems that SDS-PAGE is characterizing at the strain level (unique profiles are obtained for each individual strain). Consequently, no taxonomic conclusions can be draw at the species level. Therefore the construction of a database of protein fingerprints is an important tool for the identification and characterization of these organisms.291798

Genotypic diversity and virulence traits of Streptococcus mutans in caries-free and caries-active individuals

The present study evaluated the relationship between clonal diversity and some virulence traits of Streptococcus mutans isolated from eight caries-free and eight caries-active subjects. A total of 155 S. mutans isolates from caries-free subjects and 144 isolates from caries-active subjects were obtained from samples of saliva, dental plaque and tongue surface and identified by PCR. The isolates were submitted to arbitrarily primed (AP)-PCR (OPA-2 and OPA-13) and multilocus enzyme electrophoresis (MILEE) to establish the genotypic diversity. Production of water-insoluble glucan (WIG) (monitored by SIDS-PAGE), final pH of cultures and the ability of bacterial cells to adhere to smooth glass in the presence of sucrose were measured. High and comparable abilities of MLEE and AP-PCR were found to distinguish S. mutans genotypes, using Simpson's index of discrimination (0.971 and 0.968, respectively). The results showed a significant difference (P<0.01) in the number of genotypes when caries-free and caries-active groups were compared by both fingerprinting methods used. Final pH (P=0.32) and the percentage of adherence to a glass surface (P=0.62) did not show differences between the two groups; however, the intensities of WIG bands from the caries-active group were greater than those from the caries-free group (P<0.01). In addition, WIG was positively correlated with the ability of S. mutans to adhere to a glass surface (r = 0.34, P=0.02) from caries-active subjects. These data showed that AP-PCR analysis and MLEE are both effective methods for assessing the genetic relatedness of S. mutans. Using these techniques, it was found that there is a larger number of genotypes of S. mutans with increased ability to synthesize WIG in caries-active individuals.53769770

Proposal of protocols using D-glutamine to optimize the 2,3-bis (2-methoxy-4-nitro-5-sulfophenly)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT) assay for indirect estimation of microbial loads in biofilms of medical importance

Due to technical problems, biofilm biomasses are difficult to be precisely determined. One reliable strategy is based on the colorimetry of formazan compounds derived from tetrazolium salt reduction. XTT presents some desirable properties that make the biofilm measurements easier. However, cells entrapped within the extracellular matrixes normally do not metabolize the tetrazolium equally, leading to underestimation of cell contents. This study evaluated the effectiveness of D-glutamine, a plerotic substrate of tricarboxilic acid cycle (TAC), as inducer of KIT reduction. The metabolic activities of aerobic and anaerobic 48 h-old monospecific biofilms of Pseudomonas aeruginosa ATCC (R) 27853 (TM). Klebsiella pneumoniae ATCC (R) 13883 (TM). Staphylococcus epidermidis ATCC (R) 12228 (TM). Streptococcus mutans ATCC (R) 25175 (TM), and Candida albicans SC5314 were evaluated. Results showed that D-glutamine 50 mM (for P. aeruginosa, K. pneumoniae, and S. epidermidis) and 25 mM (for S. mutans and C albicans) may enhance the detection of soluble formazan in a significant manner, what becomes the XTT reduction assay more robust. (C) 2011 Elsevier B.V. All rights reserved.84229930

Time-related Increase of Staphylococci, Enterobacteriaceae and Yeasts in the Oral Cavities of Comatose Patients

Background/Purpose: The composition of oral microbiota in comatose patients remains uncertain. Some pulmonary pathogens may be found in dental biofilms or as part of the saliva microbiota. It is supposed that some pneumopathogenic microorganisms may overgrow in the mouths of comatose patients and spread to their lungs. Methods: The oral colonization dynamics of staphylococci, Enterobacteriaceae and yeasts in nine comatose patients (group 1), and in 12 conscious patients that brushed their teeth at least twice a day (group 2) was evaluated. Both groups were followed up for 7 days after hospitalization. Daily samples of saliva were obtained, dispersed and plated on selective culture media and colony forming units of each microbial group were obtained. Results: For patients in group 1, the counts of total viable bacteria, staphylococci, Enterobacteriaceae and yeasts progressively increased in a time-dependant manner. For the conscious patients of group 2, there was no increase. Conclusion: It would appear that concomitant consciousness and brushing teeth are determinants in controlling the selected pneumopathogen counts in resting saliva. The increase in microbial counts in comatose patients is understandable because these microorganisms could spread to the lungs. © 2010 Taiwan Society of Microbiology.link_to_OA_fulltex