Modified Littman Oxgall Agar to Isolate Cryptococcus neoformans

Littman Oxgall Agar was modified by adding an extract of Guizotia abyssinica seeds with a water diluent for rehydration. In this medium, colonies of Cryptococcus neoformans became brown, but the color failed to develop in eight other yeasts and yeast phases of diphasic organisms. The depression of saprophytic fungi noted on Littman Oxgall Agar was not lost in the modification.     

Modified Decarboxylase-Dihydrolase Medium

A modified base medium for amino acids is described which has advantages over Moeller and Falkow media.     

Definitions and Epidemiology of Candida Species not Susceptible to Echinocandins

Antifungal susceptibility testing of Candida against the echinocandin antifungal agents (anidulafungin [ANF], caspofungin [CSF], micafungin [MCF]) has been standardized by the Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antifungal Testing. The CLSI proposed a single set of clinical breakpoints (CBPs) for all three echinocandins and all species of Candida: susceptible, minimum inhibitory concentration (MIC) ≤ 2 μg/mL; nonsusceptible, MIC > 2 μg/mL. Subsequently, these CBPs have been shown to lack sensitivity in detecting strains of Candida with acquired resistance mechanisms associated with treatment failure. Studies using the CLSI method have defined wild-type (WT) MIC distributions and epidemiologic cutoff values (ECVs) for each echinocandin and the common species of Candida. The ECVs serve as a sensitive means of discriminating WT strains from those with acquired resistance mechanisms. WT MIC distributions revealed ECV ranges of 0.03 to 0.25 μg/mL for all major species except C. parapsilosis (1–4 μg/mL) and C. guilliermondii (4–16 μg/mL). These ECVs reliably differentiate WT strains of each species from non-WT strains containing fks mutations. These data, coupled with additional biochemical, clinical, pharmacokinetic, and pharmacodynamic considerations, have resulted in new CBPs of ≤0.25 μg/mL (susceptible), 0.5 μg/mL (intermediate), and ≥1 μg/mL (resistant) for ANF, CSF, and MCF for C. albicans, C. tropicalis, and C. krusei. For these agents and C. parapsilosis, the new CBPs are ≤2 μg/mL (susceptible), 4 μg/mL (intermediate), and ≥8 μg/mL (resistant). For C. glabrata, the CBPs for ANF and CSF are ≤0.12 μg/mL (susceptible), 0.25 μg/mL (intermediate), and ≥0.5 μg/mL (resistant), whereas those for MCF are ≤0.06 μg/mL, 0.12 μg/mL, and ≥0.25 μg/mL, respectively. Application of both ECVs and the lower species-specific CBPs for the echinocandins has proven useful in both resistance surveillance and clinical care and will serve as an important step in international harmonization of in vitro susceptibility testing of this important antifungal class.     

Evaluation of the Adherence of Candida Species to Urinary Catheters

Catheter-associated urinary tract infections (CAUTIs) are the most common kind of nosocomial infection. Recent years have seen a significant increase in numbers of infections caused by yeasts of the genus Candida. The adherence of a microorganism to the host surface is a decisive factor in the success of colonization and the pathogenesis of infection. The objective of this work was to evaluate the adherence of species of the genus Candida to urinary catheters. In vitro adherence to the sections of latex and silicon catheters of Candida albicans and Candida parapsilosis were studied. Adherence was measured by counting the number of adhering viable cells and the results were expressed as Colonies Forming Units per mL. The results demonstrated that the latex catheter facilitated adherence more than the silicon catheter (p < 0.01). The adherence of the C. albicans was significantly greater than C. parapsilosis on latex, but it was similar on silicon.     

Mycocinotyping of Some Unaffiliated Candida Species

Microbiology - The studied type strains from the phylogenetically unaffiliated Candida species are insensitive to mycocins of ascosporogenous yeasts of seven genera some of which were active...     

Selective Culture Medium to Survey the Incidence of Haemophilus Species

A culture medium for the selective isolation of Haemophilus species is described. Bacitracin and nutritional supplements were incorporated in a rich basal agar medium to which rabbit blood was added to distinguish hemolytic species. Colony counts of seven typed strains of H. influenzae on this medium were within practical limits of counts on other media tested for clinical use. The bacitracin medium was as reliable as hemoglobin-agar for detecting H. influenzae and more sensitive for detecting other Haemophilus species in a clinical survey with the advantage of selectivity.     

Species characteristics of experimental Candida lung lesions

Intratracheal challenge of rabbits and intranasal challenge of white mice and guinea-pigs by C. albicans without the application of adhesive substances, produced candidiasis pneumonia running more severe course in mice than in rabbits. In guinea-pigs the disease was of medium severity. Specific features of pulmonary inflammation in rabbits were marked polynuclear and especially macrophage reactions, with the phagocyte activity high enough to ensure total elimination of pathogenic microorganisms in the animal. In white mice a weak macrophage reaction was actually a background for a predominant polynuclear reaction producing a massive polynuclear leukocyte disintegration. These processes, though eliminating pathogenic organisms both by phagocytosis and non-phagocytic mechanisms, lead to severe fatal pulmonary edema. Specific differences in experimental lung candidiasis reveal various manifestation of human lung candidiasis.     

Multipurpose Medium for Use with Pseudomonas Species

A medium is described which can be used to detect starch hydrolysis, gelatinase production, and denitrification by pseudomonads.     

PCR-SSCP技术在假丝酵母属菌种鉴别中的应用

选取中国工业微生物菌种保藏管理中心(CICC)保藏的假丝酵母属的7个种30株菌, 对其rDNA的ITS1区及ITS2区进行了PCR-SSCP指纹图谱分析, 结果表明在假丝酵母属种水平的区分鉴定中, ITS1区与ITS2区的PCR-SSCP图谱均能对本研究所选7个种的菌株进行显著区分, 比较两个区段的PCR-SSCP图谱及鉴别效果, 发现ITS2区的应用效果要优于ITS1区。     

A Modified Polyester Embedding Medium for Sectioning

A modified polyester resin designated as C. M. E. Tissue Support Resin can be cut on a rotary microtome and can yield sections from 5 to 50μ from tissue blocks that range from 5 to 16 mm in diameter. It is firm enough to support hard structures that lie adjacent to soft ones and retain all in their normal position. The resin-catalyst-promoter system cures oi hardens at a low temperature so that blocks are ready for cutting 6 hr aftei tissue has been routinely dehydrated. The resin is compounded from a plasticized rigid polyester and adjusted to a proper viscosity. Several grades of hardness can be attained by changing the formula. It has been tested with both soft and hard tissues, including limbs and tails of 7-mo old mice and mature whole grains of wheat, and provides a more substantial and more readily prepared embedding medium than celloidin. Sections can be stained before mounting, without removing the embedding material, with aqueous safranin O followed by fast green FCF in absolute alcohol. The plastic remains clear. Other staining processes require modifications to get good results.     

Four Pathogenic Candida Species Differ in Salt Tolerance

The virulence of Candida species depends on many environmental conditions, including extracellular pH and concentration of alkali metal cations. Tests of the tolerance/sensitivity of four pathogenic Candida species (C. albicans, C. dubliniensis, C. glabrata, and C. parapsilosis) to alkali metal cations under various growth conditions revealed significant differences among these species. Though all of them can be classified as rather osmotolerant yeast species, they exhibit different levels of tolerance to different salts. C. parapsilosis and C. albicans are the most salt-tolerant in general; C. dubliniensis is the least tolerant on rich YPD media and C. glabrata on acidic (pH 3.5) minimal YNB medium. C. dubliniensis is relatively salt-sensitive in spite of its ability to maintain as high intracellular K⁺/Na⁺ ratio as its highly salt-tolerant relative C. albicans. On the other hand, C. parapsilosis can grow in the presence of very high external NaCl concentrations in spite of its high intracellular Na⁺ concentrations (and thus lower K⁺/Na⁺ ratio) and thus resembles salt-tolerant (halophilic) Debaryomyces hansenii.     

Modified Sabouraud Medium Containing Neomycin and Polymyxin

A commercially available antibiotic mixture effectively decreased overgrowth of Sabouraud medium by gram-negative flora frequently found in the sputum of hospitalized patients.