Candida albicans ; genetics ; pathogenicity ; Extracellular Matrix ; metabolism

BACKGROUNDCandida albicans (C. albicans) strains can spontaneously switch at a very low frequency from white to opaque phase. The ability to switch reversibly between white and opaque phenotype and contributes to the pathogenicity of C. albicans. White and opaque switching can be induced by various environmental signals. Previous study showed that opaque cells switch en masse to white when transferred in vitro to 37°C, the temperature of their animal host. The objective of the present study was to determine the effect of different concentration of carbon dioxide and temperature on white-opaque switching, and to determine the different anti-candida killing activity of white and opaque form by human monocyte-macrophage cell line THP-1.

METHODSWhite-opaque switching and opaque-white switching were assayed. Modified Lee's medium supplemented with phloxine B was used to detect white and opaque forms of C. albicans under 0.03% CO2 at 25°C, 0.03% CO2 at 37°C and 5% CO2 at 37°C. Growth curve of C. albicans was monitored using OD value at 630 nm simultaneously. White and opaque forms of C. albicans and THP-1 cells were cocultured at ratio of 1:10. Colony serial dilutions were used to assay for intracellular candidacidal activity. MTT assay was used to measure the extracellular candidacidal activity.

RESULTSPhenotype switching was successfully induced in vitro in all three strains of C. albicans. When evaluating white to opaque switching, opaque colony proportion of all colonies was 0.572 ± 0.087, 0.920 ± 0.030 and 0.985 ± 0.026 exposure of white cells to 0.03% CO2 at 25°C, 0.03% CO2 at 37°C and 5% CO2 at 37°C. When evaluating opaque to white switching, opaque colony proportion of all colonies was 0.600 ± 0.114, 0.983 ± 0.003 and 0.998 ± 0.003 exposure of white cells to 0.03% CO2 at 25°C, 0.03% CO2 at 37°C and 5% CO2 at 37°C. No significant difference of white or opaque form growth rate was found among three conditions (P > 0.05). THP-1 mediated extracellular anti-candida activity in white form was (79.80 ± 3.71)% and (56.28 ± 19.12)% at different dilution ratio, which were significantly lower than that in opaque form (100%, P < 0.01). THP-1 mediated intracellular anti-candida activity in white form ((62.98 ± 5.02)%) was significantly lower than that in opaque form ((87.07 ± 1.80)%, P < 0.01).

CONCLUSIONSOur results showed that opaque form is more vulnerable and less virulent than that in white form. It suggested that higher concentration of CO2 and 37°C in host niches stabilize the less virulent opaque cell of C. albicans, which might have implications for pathogenesis, commensalism and mating.

Candida albicans ; pathogenicity ; Carbon Dioxide ; pharmacology ; Macrophages ; immunology ; Phagocytosis ; Phenotype ; Temperature ; Virulence

OBJECTIVETo study the influence of Candida albicans on human immunodeficiency virus (HIV)-positive individuals susceptible to oral candidiasis.

METHODSIn vitro secreted aspartyl proteinase activities, adhesion to healthy buccal epithelial cells of Candida albicans isolates from oral cavities of subjects with and without HIV infection were measured.

RESULTSThe pathogenetic isolates of Candida albicans from HIV-positive patients were significantly lower than that from HIV-negative subjects (P < 0.01) in secreted aspartyl proteinase activities and adhesion to buccal epithelial cells. There was no difference in commensals between these two groups. In the HIV-positive group, no difference was found between the pathogenetics and the commensals. However, in the HIV-negative group, the virulence of the pathogen was significantly higher than the commensals (P < 0.01).

CONCLUSIONSThese results indicate that oral candidiasis was not correlated with some predominant strains of Candida albicans with higher virulence in HIV-positive subjects.

Acquired Immunodeficiency Syndrome ; microbiology ; Candida albicans ; pathogenicity ; Candidiasis, Oral ; microbiology ; HIV Seropositivity ; microbiology ; Humans

BACKGROUND: Adhesion, biofilm formation, yeast-hyphal transition, secretion of enzymes, and hemolytic activity are all considered important factors in Candida tropicalis infection. However, DNA sequence data for this pathogen are limited. In this study, the polymorphism and heterogeneity of genes agglutinin-like sequences (ALS)2, Lipase (LIP)1, LIP4, and secretory aspartyl proteinase tropicalis (SAPT)1-4 as well as the relationship between phenotype and genotype were analyzed. METHODS: This study started in August 2013, and ended in July 2017. The complete length of ALS2, LIP1, LIP4, and SAPT1-4 of 68 clinical C. tropicalis isolates was sequenced. Single nucleotide polymorphisms (SNPs) as well as insertions and deletions (indels) were identified within these genes. In addition, phenotypic characteristics of the virulent factors, including adhesion and the secretion of aspartyl proteinases and phospholipases, were determined. RESULTS: There were 73, 24, 17, 16, 13, and 180 SNPs in the genes LIP1, LIP4, SAPT1, SAPT2, SAPT3, and SAPT4, respectively. Furthermore, 209 SNPs were identified in total for the gene ALS2. Interestingly, large fragment deletions and insertions were also found in ALS2. Isolate FXCT 01 obtained from blood had deletions on all 4 sites and showed the lowest adhesion ability on the polymethylpentene surface. In addition, isolates with deletions in the regions 1697 to 1925 and 2073 to 2272 bp displayed relatively low abilities for adhesion and biofilm formation, and this phenotype correlated with the deletions found in ALS2. LIP1, SAPT4, and ALS2 displayed great heterogeneity among the isolates. Large deletions found in gene ALS2 appeared to be associated with the low ability of adhesion and biofilm formation of C. tropicalis. CONCLUSION This study might be useful for deeper explorations of gene function and studying the virulent mechanisms of C. tropicalis.
Bacterial Adhesion ; Biofilms ; Candida tropicalis ; genetics ; pathogenicity ; Lipase ; genetics ; Polymorphism, Single Nucleotide ; Virulence ; genetics

BACKGROUNDBroad-spectrum antibiotic administration promotes intestinal colonization of exogenous fungal pathogens in healthy animals and has been recognized as one of the risk factors of invasive fungal infection in clinical settings. It is unclear whether broad-spectrum antibiotic treatment would change the intestinal mycobiota without exogenous fungal challenge in the context of sepsis.

METHODSWe established a rat model of double-hit sepsis using burn injury and endotoxin challenge. Rats with burn injury or double-hit sepsis received imipenem treatment for 3 days or 9 days, and their colon contents were sampled for selective fungal culture and isolation counts.

RESULTSImipenem treatment promoted the overgrowth of the commensal fungus Geotrichum capitatum in rats with burn injury. Imipenem treatment also promoted colon colonization by exogenous fungi in rats with burn injury and double-hit sepsis, including Trichosporon cutaneum, Candida albicans, Candida krusei, and Candida glabrata. A longer duration of imipenem treatment had a stronger impact on colon colonization by exogenous fungi.

CONCLUSIONImipenem treatment facilitates the overgrowth of commensal fungi and colonization by exogenous, potentially pathogenic fungi in the colons of rats with burn injury or double-hit sepsis.

Animals ; Anti-Bacterial Agents ; therapeutic use ; Burns ; complications ; microbiology ; Candida ; pathogenicity ; Colon ; microbiology ; Imipenem ; therapeutic use ; Male ; Rats ; Rats, Sprague-Dawley ; Sepsis ; drug therapy ; microbiology ; Trichosporon ; pathogenicity

Candida ; pathogenicity ; Cross Infection ; microbiology ; prevention & control ; Gram-Negative Bacteria ; pathogenicity ; Humans ; Intensive Care Units ; statistics & numerical data ; Sepsis ; microbiology ; prevention & control

INTRODUCTIONEarly detection of catheter-related candidemia is necessary to ensure that patients receive prompt and appropriate treatment. The aim of the present case-control study is to investigate the clinical features of catheter-related candidemia at disease onset, so as to determine the clinical indications for empiric antifungal therapy.

METHODSAll 41 cases of catheter-related candidemia from September 2009 to August 2011 at a teaching hospital were included in the present study. To determine the characteristics that were risk factors for developing catheter-related candidemia, we compared all cases of catheter-related candidemia with all 107 cases of catheter-related blood stream infection (CRBSI) caused by non-Candida spp.

RESULTSIn comparison with CRBSI due to non-Candida spp., the duration of catheter use was significantly longer in cases of catheter-related candidemia (13.9 ± 9.0 days vs. 23.2 ± 25.2 days). There was also a significant difference in the frequency of pre-antibiotic treatment between catheter-related candidemia and CRBSI due to non-Candida spp. (97.6% [40/41 cases] vs. 44.9% [48/107 cases]). Patients with catheter-related candidemia also had significantly more severe clinical statuses (measured using the Sepsis-related Organ Failure Assessment score) than patients with CRBSI due to non-Candida spp. (7.63 ± 3.65 vs. 5.92 ± 2.81).

CONCLUSIONWhen compared to patients with CRBSI caused by non-Candida spp., patients with catheter-related candidemia had significantly more severe clinical backgrounds, longer duration of catheter use and more frequent prior administration of antibiotic agents.

Aged ; Aged, 80 and over ; Candida ; pathogenicity ; Candidemia ; diagnosis ; Case-Control Studies ; Catheter-Related Infections ; diagnosis ; Female ; Humans ; Male ; Middle Aged

Candida is a commensal organism that is frequently found in the human gastrointestinal tract. It is the most common organism that causes pancreatic fungal infections. However, magnetic resonance imaging findings of Candida infection in the pancreas have not been described. We report imaging findings of pancreatic candidiasis in a patient in immunocompetent condition. It presented as a multi-septated cystic mass with a peripheral solid component in the background of pancreatitis and restricted diffusion on diffusion-weighted image that mimicked a malignant pancreatic cystic tumor.
Candida/pathogenicity ; Candidiasis/*diagnosis/microbiology/radiography ; Diagnosis, Differential ; Humans ; Immunocompromised Host ; Magnetic Resonance Imaging/methods ; Male ; Middle Aged ; Pancreatic Neoplasms/*diagnosis/radiography ; Pancreatitis/*diagnosis/microbiology/radiography

The aim of this study was to investigate the clinical situation of invasive fungal infections in patients with hematological malignancies, and discuss the susceptible factors and precautions. 541 patients with hematological malignancies from 2008 Jan to 2011 Dec in hospital 307 of Chinese PLA were statistically retrospectively analyzed in term of clinical manifestation, image examination, culture results of secretions, therapy and so on. The results showed that 63 out of 541 patients got invasive fungal infections. The respiratory tract and intestinal tract were the most common infection sites (62.34 and 19.48, respectively); Candida albicans (66.67) and Candida glabrata (12.82) were the most common pathogens. It is concluded that the main risk factors are as follows: primary diseases, chemotherapy, glucocorticoid, leukopenia after chemotherapy, applications of broad-spectrum antibiotics and aging. It is suggested that a stratification of risk factors is helpful in preventing and treating invasive fungal infections.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Candida ; pathogenicity ; Child ; Cross Infection ; microbiology ; Female ; Hematologic Neoplasms ; complications ; microbiology ; Humans ; Male ; Middle Aged ; Mycoses ; complications ; microbiology ; Retrospective Studies ; Young Adult

BACKGROUNDCandidal esophagitis is the primary infection among all digestive tract opportunistic ones in acquired immunodeficiency syndrome (AIDS) cases. X-ray manifestation reports of it are still rare. This study aimed to conduct a retrospective analysis on the X-ray data of 6 AIDS cases complicated with candidal esophagitis, and to study the X-ray characteristics of it combined with the findings from gastroscopy.

METHODSAmong 6 cases in this series, all cases were confirmed by Shenzhen Center for Disease Control and Prevention (CDC) to be HIV positive and all of them had CD4 cell counts less than 150 × 10(6)/L. All cases underwent X-ray and gastroscopy, and mycelium were found in the mucous membrane of the esophagus.

RESULTSIn this series, the findings of the X-ray were as follows: (1) Affected areas: Four cases in the whole esophagus, 2 cases in the middle and lower part of esophagus; (2) Abnormal motivity: Six cases had decreased tension, loose walls, weakened peristalsis, decreased number of peristalsis waves and delayed emptying of barium; (3) Abnormal contour: Six cases had the sign of "decorative border" or "brush", two cases had narrowed canal; (4) Abnormal membrane and "cobblestone sign": Six cases had thickened membrane and "cobblestone sign" on the surface of the abnormal membrane. The hyperemia of mucosa was covered tightly with yellow-white pseudomembrane spots. This was in accordance with the small cobblestone-like filling defect found by X-ray.

CONCLUSIONSIf the AIDS cases have dysphagia, and X-ray shows that more than two sections of the esophagus are affected, with decreased motility, the walls in the sign of "brush" or "decorative edges", thickened membrane with "cobblestone sign", candidal esophagitis is highly possible.

Acquired Immunodeficiency Syndrome ; diagnosis ; diagnostic imaging ; Adult ; Candida ; pathogenicity ; Candidiasis ; diagnosis ; diagnostic imaging ; microbiology ; Esophagitis ; diagnosis ; diagnostic imaging ; microbiology ; Female ; Humans ; Male ; Radiography