Characterization of biofilms formed by Candida parapsilosis, C. metapsilosis, and C. orthopsilosis

Infections due to Candida parapsilosis have been associated with the ability of this fungus to form biofilms on indwelling medical devices. Recently, C. parapsilosis isolates were reclassified into 3 genetically non-identical classes: C. parapsilosis, C. orthopsilosis, and C. metapsilosis. Little information is available regarding the ability of these newly reclassified species to form biofilms on biomedical substrates. In this study, we characterized biofilm formation by 10 clinical isolates each of C. parapsilosis, C. orthopsilosis, and C. metapsilosis. Biofilms were allowed to form on silicone elastomer discs to early (6 h) or mature (48 h) phases and quantified by tetrazolium (XTT) and dry weight assays. Surface topography and three-dimensional architecture of the biofilms were visualized using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), respectively. Metabolic activity assay revealed strain-dependent biofilm forming ability of the 3 species tested, while biomass determination revealed that all 3 species formed equivalent biofilms (P>0.05 for all comparisons). SEM analyses of representative isolates of these species showed biofilms with clusters of yeast cells adherent to the catheter surface. Additionally, confocal microscopy analyses showed the presence of cells embedded in biofilms ranging in thickness between 62 and 85 μm. These results demonstrate that similar to C. parapsilosis, the 2 newly identified Candida species (C. orthopsilosis and C. metapsilosis) were able to form biofilms.     

The SEEDs of two gastrointestinal diseases: socioeconomic, environmental, and demographic factors related to cryptosporidiosis and giardiasis in Massachusetts

Objectives

We assessed associations between community-level socioeconomic, demographic, and environmental characteristics, and the presence of two potentially waterborne infectious diseases, cryptosporidiosis and giardiasis, as reported to the Massachusetts Department of Public Health.

Methods

We created a series of maps showing the spatial distribution of cryptosporidiosis and giardiasis in Massachusetts (1993-2002) overall and by age, using logistic regression to analyze associations between community-level characteristics and the presence of at least one reported case of each disease. This analysis was repeated for communities with predominantly private water supplies.

Result

After adjusting for population size, higher population density and larger than average household sizes were associated with increased odds of reported cases of cryptosporidiosis. Giardiasis was also associated with high population density, but was not associated with household size. In the elderly, income was positively associated with the presence of giardiasis.

Discussion

These findings suggest that greater population density and larger household sizes may increase the likelihood of protozoan gastrointestinal infection. The results emphasize the necessity to account for distal factors, such as demographic characteristics, that may ultimately play a role in the transmission or reporting of disease.     

Itolizumab in combination with methotrexate modulates active rheumatoid arthritis: safety and efficacy from a phase 2, randomized,open-label,parallel-group,dose-ranging study

Clinical Rheumatology - The objective of this study was to assess the safety and efficacy of itolizumab with methotrexate in active rheumatoid arthritis (RA) patients who had inadequate response to...     

MTHFR C677T and A1298C polymorphisms and risk of nonsyndromic orofacial clefts in a south Indian population

Objectives

Several lines of evidence suggest that the decrease in folate in periconceptional period or maternal use of folate antagonists has been associated with a higher risk of orofacial clefts (OFCs). MTHFR is a critical enzyme in folate metabolism that catalyzes the irreversible conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, thus playing a vital role in DNA synthesis and DNA methylation. The aim of our study was to determine whether there is any association between the susceptibility to Nonsyndromic cleft lip with or without cleft palate (NSCL/P) amongst the variations of MTHFR genotypes in South Indian population.

Methods

Our sample comprised 123 cases with NSCL/P and 141 controls without clefts or family history of clefting. The most common polymorphisms C677T (rs1801133) and A1298C (rs1801131) on the MTHFR gene were screened for the genotypes using PCR-RFLP.

Results

Both C677T and A1298C are polymorphic with minor allele frequencies of 0.131 and 0.429, respectively, for controls. Genotype data in control and cleft groups are following the Hardy Weinberg Equilibrium. There were no significant differences in genotypes of both polymorphisms between controls and NSCL/P. The pairwise LD values (D′ and r²) between C677T and A1298C are 1.0 and 0.096 respectively indicating no significant LD between these two SNPs. Haplotype phenotype analysis did not show the evidence for association. Gene–gene interaction showed the distribution of the observed combinations of the two MTHFR polymorphisms was not different between NSCL/P and controls (p = 0.887).

Conclusions

Our results do not support the hypothesis, that variants in the MTHFR gene confer a risk for NSCL/P in the South Indian population.     

Novel Antiseptic Urinary Catheters for Prevention of Urinary Tract Infections: Correlation of In Vivo and In Vitro Test Results

Urinary catheters are widely used for hospitalized patients and are often associated with high rates of urinary tract infection. We evaluated in vitro the antiadherence activity of a novel antiseptic Gendine-coated urinary catheter against several multidrug-resistant bacteria. Gendine-coated urinary catheters were compared to silver hydrogel-coated Foley catheters and uncoated catheters. Bacterial biofilm formation was assessed by quantitative culture and scanning electron microscopy. These data were further correlated to an in vivo rabbit model. We challenged 31 rabbits daily for 4 days by inoculating the urethral meatus with 1.0 × 10⁹ CFU streptomycin-resistant Escherichia coli per day. In vitro, Gendine-coated urinary catheters reduced the CFU of all organisms tested for biofilm adherence compared with uncoated and silver hydrogel-coated catheters (P < 0.004). Scanning electron microscopy analysis showed that a thick biofilm overlaid the control catheter and the silver hydrogel-coated catheters but not the Gendine-coated urinary catheter. Similar results were found with the rabbit model. Bacteriuria was present in 60% of rabbits with uncoated catheters and 71% of those with silver hydrogel-coated catheters (P < 0.01) but not in those with Gendine-coated urinary catheters. No rabbits with Gendine-coated urinary catheters had invasive bladder infections. Histopathologic assessment revealed no differences in toxicity or staining. Gendine-coated urinary catheters were more efficacious in preventing catheter-associated colonization and urinary tract infections than were silver hydrogel-coated Foley catheters and uncoated catheters.In the United States, nosocomial catheter-related urinary tract infections (UTIs) account for almost 1 million cases (24) and approximately 31% of nosocomial infections seen in the intensive care unit each year (16). Approximately 10% to 30% of patients with indwelling bladder catheters develop bacteruria or UTI (24). This contributes not only to increased morbidity and mortality but also to longer hospital stays and increased medical costs (13). Microbiologic cultures of catheter-related UTIs in the intensive care unit reveal several common pathogens. Of these, Escherichia coli and Pseudomonas aeruginosa account for over 39%.Several different methods have been used to prevent nosocomial UTIs. Of these, the most common and longest-used method is the sterile closed drainage system, which has substantially reduced the prevalence of catheter-associated UTIs (11). More recently, other preventive methods involving the use of antimicrobial devices, including urinary catheters impregnated with silver, nitrofurazone, and a combination of minocycline and rifampin (rifampicin), have led to a reduced incidence of bacteruria; however, they were not significant at preventing catheter-related UTIs compared to results with uncoated controls (4, 12, 22).The use of antibiotic (minocycline and rifampin)-impregnated catheters has led to a reduced incidence of gram-positive bacteruria (4). However, given the fact that bacterial resistance to antibiotics has been increasing, this has resulted in a demand for an alternative means of an antiseptic coating that has not been associated with increased resistance. At the M. D. Anderson Cancer Center, we developed a technique of impregnating urinary catheters with Gendine, a novel antiseptic dye consisting of Gentian violet and chlorhexidine, to prevent catheter-related UTIs. In this study, we evaluated Gendine-coated silicone urinary catheters (GND-UCs) for their in vitro antimicrobial efficacy at inhibiting microbial biofilm formation on catheter surfaces and at reducing the incidence of UTIs in an in vivo rabbit model in comparison with results for silver hydrogel-coated catheters and uncoated Foley catheters.