Is Candida Contagious?

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Open modal Abstract Candida parapsilosis is an important non-albicans species which infects hospitalized patients. No studies have correlated outbreak infections of C. We used DNA fingerprinting to determine genetic variability among isolates from a C.

We compared phenotypic markers of pathogenesis, including adherence, biofilm formation, and protein secretion secretory aspartic protease [SAP] and phospholipase. Adherence was measured as colony counts on silicone elastomer disks immersed in agar. Biofilms formed on disks were quantified by dry weight.

SAP expression was measured by hydrolysis of bovine albumin; a colorimetric assay was used to quantitate phospholipase. DNA fingerprinting indicated that the outbreak isolates were clonal and genetically distinct from our database. Adherence and protein secretion did not correlate with strain pathogenicity.

These results suggest that biofilm production plays a role in C. The yeast Candida is the fourth most common cause of hospital-related bloodstream infections 1. Although C. The affinity of C. Our understanding of fungal virulence factors is limited.

The surface adherence capacity of Candida is likely one such factor, possibly linked to its subsequent ability to form biofilms Clinically obtained C. Adhesion 15 and biofilm formation 14 may be especially important for C. Total parenteral nutrition TPN solutions may promote C. Recently, biofilm-forming potential was cited as a reason that patients with C.

Fungi secrete enzymes integral to pathogenesis. Phospholipases e. Although phospholipase B expression has been well studied in C. The role of SAP and pathogenesis is similarly unclear We characterized genetic and phenotypic characteristics of isolates from a C.

We performed molecular characterization, comparing C. We then compared adhesion ability, biofilm production, and secretion of SAP and phospholipase B of the outbreak isolates and our clinical strains.

Methods Organisms Outbreak isolates of C. Epidemiologic details regarding the organisms and patients have been published elsewhere Isolates from sporadic infections were from the culture collection at the Center for Medical Mycology, University Hospitals of Cleveland University Hospitals.

The site of isolation of other strains is indicated in the figures. Organism propagation has been described previously All specimens were stored and used without patient identifiers, to maintain confidentiality. Processed hybridization patterns were scanned to identify and link common bands. The SAB ranges from 0. Adherence Assays Adherence of Candida parapsilosis contagio. Wakefield, MA and prepared as described After injection, disks were washed in phosphate-buffered saline PBS to remove nonadherent cells and placed in wells of well tissue culture plates Becton Dickinson, Franklin Lakes, NJ.

Biofilm Formation and Quantitation C. Control disks were handled identically, except that no blastospores were added. Biofilm quantitation was performed as described 21 with dry weight measurements. Dry weight measured total biofilm mass including fungal cells and extracellular matrix. We grew C. To confirm relevance of our findings to those of previous studies, we examined SAP expression of organisms grown in the expression medium and found similar results data not shown.

The appearance of a kDa band was indicative of SAP activity. Quantitation of this band was determined by using QuantOne software v4. Phospholipase Assays A colorimetric assay for free fatty acid FFA was used to assess phospholipase activity The relative level of free fatty acids in each sample was determined by using an acyl-CoA-oxidase system assay kit Roche Molecular Biochemicals, Indianapolis, IN.

Statistical Analysis Adherence and biofilm experiments were performed in quadruplicate and on separate days. Results for different isolates were normalized to C. Phospholipase and SAP assays were performed at least twice; representative results are shown. Statistical analysis was performed by using StatView v5. Genetic analysis of Candida parapsilosis clinical isolates. Southern blot hybridization patterns of the 14 C.

The reference strain J was Isolate relatedness was investigated by using the complex DNA fingerprinting probe Cp As shown in Figure 1the five invasive strains and one of the three environmental isolates generated identical patterns. The two remaining strains and were hand isolates. The fingerprinting pattern of strain was limited to weak bands, while none were obtained for Figure 2 Figure 2.

Relatedness of Candida parapsilosis clinical isolates. Dendrogram generated from SABs computed for pairwise comparisons of the 14 C. Note that These analyses showed that the six outbreak isolates were identical and belonged to group I strains The remaining isolates appeared moderately related to unrelated at the genetic level, and therefore were non—group I strains. Previous studies have shown that Cp fingerprinting patterns made up of a few weak bands typically belong to groups II or III, representing a minority of C.

However, internally transcribed spacer region sequencing of strain indicates that it, in fact, belongs to group 1 D. Warnock, pers. Alternately, this finding may candida parapsilosis contagio past genetic exchanges between group I and non—group I strains. Adherence Figure 3 Figure 3. Adherence properties of Candida parapsilosis clinical isolates. Graph shows adhesion ability of various C. Results were normalized Adherence to substrate, whether natural endothelium or artificial catheter materialis likely the first step in Candida pathogenesis As shown in Figure 3the adherence abilities of C.

Adherence was the same for outbreak isolates of the same clone,; other clonal isolates were excluded for clarityregardless of the site of isolation. Biofilm Production Figure 4 Figure 4. Relative dry weight of biofilms formed by Candida parapsilosis clinical isolates. Panel A shows relative dry weight of the C. We first determined the ability of the C. All isolates of the same clone strains,and showed a similar pattern of biofilm formation by dry weight Figure 4Awhich suggests that biofilm formation by these isolates is consistent and not site-induced.

Figure 4B shows a comparison of biofilm formation by the C. However, the pattern of results across strains was similar to YNB-based method not shown.

Secretory aspartic protease SAP expression by Candida parapsilosis clinical isolates. Panel A shows representative sodium dodecyl sulfate—polyacrylamide gel electrophoresis of various C. M, molecular weight marker lane; BSA, bovine We measured SAP production by assaying the ability of C.

The appearance of specific digestion products was noted when culture supernatant was added to BSA. This indicated that the kDa band was a specific by-product of supernatant protease activity, present in all supernatants except for strains M61 and Analysis of the protease activity of culture supernatants was performed by densitometric scanning of the kDa band.

As seen in Figure 5Bthe intensity of the kDa product varied greatly between candida parapsilosis contagio and within the outbreak clonal isolates, and no consistent pattern of protease activity was evident.

These results were confirmed in multiple experiments. Phospholipase Assays Figure 6 Figure 6. Phospholipase expression by Candida parapsilosis clinical isolates. Phospholipase expression as determined by the colorimetric method is shown. We determined the phospholipase activity of supernatants obtained from cultures of the different C.

For comparative purposes, we included the phospholipase activity of C. Although phospholipase activity varied among strains Figure 6no consistent differences were observed between sources outbreak vs. University Hospitalssites e. Discussion We studied a nosocomial outbreak of C.

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