Effect of surface treatments of titanium on amphotericin B-treated Candida albicans persister cells.

Although persister cells in Candida albicans biofilm may contribute to its increased resistance to antifungal drugs, little information is available on the formation of Candida persister cells on titanium surfaces. The effect of different surface treatments of Ti on persister cells was determined in the present study. Titanium discs were surface-treated by three different methods (Group A - polishing, Group B - sandblasting followed by acid-etching, and Group C - sandblasting alone). Persister cells of two C. albicans strains, namely ATCC 90028 and HK30Aa, in biofilm and planktonic states, were measured as the percentage of colony forming units remaining after 24 h incubation with various concentrations of amphotericin B. No persister cells were detected in the planktonic cultures. However, 1.5%, 0.1% and 2.4%C. albicans ATCC 90028 persister cells were detected at an AmB concentration of 64 µg ml(-1) in groups A, B and C, respectively; and 0.3%, 0.2% and 0.6% for groups A, B and C, respectively, for HK30Aa. Group C of C. albicans ATCC 90028 appeared to provide a surface relatively unfavourable for the development of persister cells (P < 0.01). Whether these results may have implications on the clinical performance of titanium implants warrants further investigation.

Shedding dynamics of Epstein-Barr virus: A type 1 carcinogen.

Epstein Barr virus (EBV) is one of the ubiquitous viral carcinogens found in humans and successfully infects more than 90% of the world population. The spectrum of EBV-related pathology ranges from asymptomatic primary infection to grave B- and T-cell malignancies. EBV triggers lymphoproliferative disorders after allogeneic stem cell transplantation, which contributes to higher mortality rates. Although the transmission of EBV primarily occurs from an infected host to a naive host through viral shedding from the oropharynx, increasing evidence points to considerable amount of shedding in other anatomical sites such as cervix, anal mucosa, breast milk and respiratory tract. It is impossible to eradicate the prevalence of EBV-related malignancies and other pathologies without preventing viral shedding. However, a detail analysis of the multifaceted nature of EBV shedding is not available in the literature. Thus, this review focuses on elucidating the key elements of the shedding dynamics of this carcinogenic virus.

Immune reconstitution inflammatory syndrome after highly active antiretroviral therapy: a review.

The use of highly active antiretroviral therapy (HAART) in the management of human immunodeficiency virus (HIV) restores immune responses against pathogens and has greatly decreased mortality. However, in about 25% to 35% of patients receiving HAART, the reconstituted immune system leads to a pathological inflammatory response, commonly known as immune reconstitution inflammatory syndrome (IRIS), which causes substantial short-term morbidity or even mortality. Although we have gleaned some knowledge on IRIS in the past few years, a number of unanswered questions remain. In this review, we discuss the definition, diagnostic criteria, pathogenesis, risk factors, clinical spectrum including oral manifestations, and management of IRIS.

HIV protease inhibitors differentially inhibit adhesion of Candida albicans to acrylic surfaces.

Highly active antiretroviral therapy (HAART), using HIV protease inhibitors, is commonly used in the management of HIV infection. HIV protease inhibitors also have a direct effect on a key virulence factor of Candida albicans, its secreted aspartyl proteinase (Sap). Although protease inhibitors can attenuate Candida adhesion to human epithelial cells, their effects on adhesion to acrylic substances, which is a common component of oral appliances, is unknown. This study investigated whether protease inhibitors affect C. albicans adhesion to acrylic substances. C. albicans suspensions were pretreated with different concentrations of saquinavir, ritonavir or indinavir for 1 h and allowed to adhere on acrylic strips, which had been pretreated with pooled human saliva for 30 min, for another hour in the presence of each drug. The test groups showed a significantly lower degree of adhesion than the controls. Adhesion was reduced by 50% at drug concentrations of 100, 100 and 20 µmol l(-1) for saquinavir, ritonavir and indinavir respectively. In conclusion, protease inhibitors attenuated C. albicans adhesion to an acrylic surface in vitro in a dose-dependent manner, and different protease inhibitors exhibited different degrees of inhibition.

Phospholipase, proteinase and haemolytic activities of Candida albicans isolated from oral cavities of patients with type 2 diabetes mellitus.

The aim of this study was to biotype and characterize phospholipase, proteinase and haemolytic activities of oral Candida albicans isolates from 210 Chinese patients with type 2 diabetes mellitus (DM) and 210 age- and sex-matched healthy controls. Seventy-six and 50 C. albicans isolates were obtained from type 2 DM patients and controls, respectively, using the oral rinse technique. The isolates were characterized with a biotyping system based on enzyme profiles, carbohydrate assimilation patterns and boric acid resistance of the yeasts, and the isolates were further tested for in vitro phospholipase, proteinase and haemolytic activities. The major biotypes of C. albicans isolates from the type 2 DM and control groups were A1R (42.1 %) and J1R (36.0 %), respectively. Significantly higher proteinase and haemolytic activities were found in the isolates from the type 2 DM group (P<0.05). Proteinase activity was higher in isolates from patients with > or =10 years of DM history than those with <10 years (P<0.05). Haemolytic activity was significantly higher in isolates from female DM patients than in those from male counterparts (P<0.05). These data provide evidence of increased extracellular enzyme activity in Candida isolates taken from DM patients.

Antifungal susceptibility of Candida albicans biofilms on titanium discs with different surface roughness.

Although it is well known that fungal biofilms have increased resistance to antimicrobial agents, limited information is available on the formation of candidal biofilms on implant surfaces with different surface roughness and their resistance to conventional antifungal therapy. In the current study, the effect of increasing the surface roughness of titanium discs on the susceptibility of Candida albicans biofilms to amphotericin B was determined. Grade I commercially pure titanium discs were sandblasted with 99.6% aluminium oxide of different grit sizes, producing surface roughness of 0.90, 1.88 and 3.82 microm (Groups A, B and C), respectively (P < 0.001). The antifungal susceptibility of C. albicans biofilm grown on different Ti discs was determined using XTT assay. The 50% reduction in metabolic activity (50% RMA) of planktonic C. albicans (0.5 microg/mL) was much lower than those from Groups A, B and C (2, 16, 2 microg/mL, respectively), while the 50% RMA from Group B was three-fold higher than those from Groups A and C. In conclusion, difference in titanium surface roughness was associated with variations in the antifungal resistance of the candidal biofilm. Group C appeared to have an optimum surface roughness for biofilm resistance.

Subgingival microbiota of renal transplant recipients.

Renal transplant patients undergoing immunosuppressive therapy may experience periodontal side-effects such as gingival overgrowth. This study evaluated the subgingival microbiota of renal transplant recipients with or without periodontal tissue destruction who may have concurrent gingival enlargement. Subgingival paper point samples taken from the deepest probing sites of 38 subjects (one per patient) were examined using direct microscopy and culture techniques. A complex microflora comprising gram-positive and gram-negative cocci, rods and filaments, fusiforms, curved rods and spirochetes was observed using microscopy. Yeasts were occasionally detected. Significantly higher proportions of gram-positive morphotypes, including gram-positive cocci, were observed in samples from periodontally healthy patients. The predominant cultivable microflora from anaerobic culture comprised several species of facultative and obligate anaerobes. Colonization of the subgingival sites by 'foreign' microbes that are normally dermal, intestinal or vaginal flora was detected in up to 50% of the samples. High mean proportions of lost or unidentified species were also occasionally noted. The results showed that the subgingival biofilm of renal transplant recipients with chronic periodontitis comprised mainly gram-negative rods and spirochetes. Besides the usual predominant cultivable subgingival microbiota associated with periodontitis, the high prevalence of unidentified and 'foreign' microbes indicates the possibility of subgingival microbial alteration in renal transplant patients.