Induction of secretory aspartyl proteinase of Candida albicans by HIV-1 but not HSV-2 or some other microorganisms associated with vaginal environment

RELATED FACTORS FOR COLONIZATION BY Candida SPECIES IN THE ORAL CAVITY OF HIV-INFECTED INDIVIDUALS

The colonization of the oral cavity is a prerequisite to the development of oropharyngeal candidiasis.

AIMS

The aims of this study were: to evaluate colonization and quantify Candida spp. in the oral cavity; to determine the predisposing factors for colonization; and to correlate the levels of CD4+ cells and viral load with the yeast count of colony forming units per milliliter (CFU/mL) in HIV-positive individuals treated at a University Hospital. Saliva samples were collected from 147 HIV patients and were plated on Sabouraud Dextrose Agar (SDA) and chromogenic agar, and incubated at 30 ºC for 72 h. Colonies with similar morphology in both media were counted and the result expressed in CFU/mL.

RESULTS

Of the 147 HIV patients, 89 had positive cultures for Candida spp., with a total of 111 isolates, of which C. albicans was the most frequent species (67.6%), and the mean of colonies counted was 8.8 × 10³ CFU/mL. The main predisposing factors for oral colonization by Candida spp. were the use of antibiotics and oral prostheses. The use of reverse transcriptase inhibitors appears to have a greater protective effect for colonization. A low CD4+ T lymphocyte count is associated with a higher density of yeast in the saliva of HIV patients.

Yeast vaginitis during pregnancy: susceptibility testing of 13 antifungal drugs and boric acid and the detection of four virulence factors

A higher prevalence of vulvovaginal candidiasis (VVC) is seen in pregnant women compared with those who are not pregnant. Recurrence is also more common in pregnant women, and therapeutic responses are reduced. In this investigation, 207 vaginal yeast isolates recovered from pregnant women were tested for susceptibility to 13 antifungal drugs and boric acid and through these studies four virulence factors were also determined. The isolates were recovered from vaginal samples of patients with acute VVC [AVVC, (n = 73)], symptomatic recurrent VVC [RVVC, (n = 89)], asymptomatic RVVC (n = 27), and those without signs and symptoms (n = 18). Candida albicans was the most common species found (59.9%), followed by C. glabrata (19.8%), other Candida spp., (19.8%), and Saccharomyces cerevisiae (0.5%). Antifungal susceptibility testing was performed as described in CLSI document M27-A3. Additionally, we examined phospholipase and proteinase production, adhesion to vaginal epithelial cells and hemolytic activity. Notably, the MIC values of Candida spp. isolates derived from patients with VVC were no different from those of the controls (P > 0.05). In addition, Candida isolates derived from patients with AVVC or RVVC produced significantly higher amounts of phospholipase and proteinase compared with the controls (P < 0.05). Antifungal testing and the determination of virulence factors may lead to the effective and prompt treatment of VVC, particularly in pregnant women.

Assessment of the Association Between HIV Viral Load and CD4 Cell Count on the Occurrence of Oropharyngeal Candidiasis in HIV-Infected Patients

BACKGROUND

Oropharyngeal candidiasis (OPC) is the most frequently observed oral infection in HIV-infected individuals. Historically, lower CD4 counts have been associated with an increased prevalence of OPC in HIV-infected patients, but HIV viral load has also recently been recognized as a possible predictive factor.

OBJECTIVE

We examined the impact of viral load and blood CD4 cell count on the occurrence of OPC using modern exploratory statistical analyses.

METHODS

The exploratory and inferential methods of classification and regression trees (CARTs) and logistic regression were used to compare the impact of viral load and CD4 cell counts on OPC status in 161 HIV-infected individuals from an outpatient clinic population in New Orleans.

RESULTS

The use of stepwise logistic regression and CART to classify individual OPC status both identified viral load as the most important covariate, followed by CD4 cells counts. Age, sex, and highly active antiretroviral therapy use were also found to be associated with OPC status.

CONCLUSIONS

These data strongly suggest that low viral load distinguishes those not at risk for OPC with high viral load, which also includes a heterogeneous set of predictors for OPC status, has the highest impact on OPC classification.

Hydrolytic enzymes as virulence factors of Candida albicans

Candida albicans is a facultative pathogenic micro-organism that has developed several virulence traits enabling invasion of host tissues and avoidance of host defence mechanisms. Virulence factors that contribute to this process are the hydrolytic enzymes. Most of them are extracellularly secreted by the fungus. The most discussed hydrolytic enzymes produced by C. albicans are secreted aspartic proteinases (Saps). The role of these Saps for C. albicans infections was carefully evaluated in numerous studies, whereas only little is known about the physiological role of the secreted phospholipases (PL) and almost nothing about the involvement of lipases (Lip) in virulence. They may play an important role in the pathogenicity of candidosis and their hydrolytic activity probably has a number of possible functions in addition to the simple role of digesting molecules for nutrition. Saps as the best-studied member of this group of hydrolytic enzymes contribute to host tissue invasion by digesting or destroying cell membranes and by degrading host surface molecules. There is also some evidence that hydrolytic enzymes are able to attack cells and molecules of the host immune system to avoid or resist antimicrobial activity. High hydrolytic activity with broad substrate specificity has been found in several Candida species, most notably in C. albicans. This activity is attributed to multigene families with at least 10 members for Saps and Lips and several members for PL B. Distinct members of these gene families are differentially regulated in various Candida infections. In future, prevention and control of Candida infections might be achieved by pharmacological or immunological tools specifically modulated to inhibit virulence factors, e.g. the family of Saps.