Ayse Kalkanci

Evaluation of epidemiological cut-off values indicates that biocide resistant subpopulations are uncommon in natural isolates of clinically-relevant microorganisms.

To date there are no clear criteria to determine whether a microbe is susceptible to biocides or not. As a starting point for distinguishing between wild-type and resistant organisms, we set out to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) distributions for four common biocides; triclosan, benzalkonium chloride, chlorhexidine and sodium hypochlorite for 3319 clinical isolates, with a particular focus on Staphylococcus aureus (N = 1635) and Salmonella spp. (N = 901) but also including Escherichia coli (N = 368), Candida albicans (N = 200), Klebsiella pneumoniae (N = 60), Enterobacter spp. (N = 54), Enterococcus faecium (N = 53), and Enterococcus faecalis (N = 56). From these data epidemiological cut-off values (ECOFFs) are proposed. As would be expected, MBCs were higher than MICs for all biocides. In most cases both values followed a normal distribution. Bimodal distributions, indicating the existence of biocide resistant subpopulations were observed for Enterobacter chlorhexidine susceptibility (both MICs and MBCs) and the susceptibility to triclosan of Enterobacter (MBC), E. coli (MBC and MIC) and S. aureus (MBC and MIC). There is a concern on the potential selection of antibiotic resistance by biocides. Our results indicate however that resistance to biocides and, hence any potential association with antibiotic resistance, is uncommon in natural populations of clinically relevant microorganisms.

Invasive fungal infections in pediatric leukemia patients receiving fluconazole prophylaxis.

Children with acute leukemia have increased risk for invasive fungal infections (IFI) but the role of long term antifungal prophylaxis (AFP) in morbidity and mortality of IFI is not well‐known.

Ocular Fungal Infections

Purpose: Microbiology, clinical perspective of ocular fungal infections, and the experimental models were overviewed. Methods: Review of published studies were evaluated and personal experience was mentioned. In this review, clinical features of keratitis and endogenous and exogenous endophthalmitis are also mentioned, but this article mainly focused on laboratory diagnosis and the experimental models of ophthalmic mycoses. Results: Fungal infections were discussed according to the anatomical part of the eye involved in the disease. Trauma is the most important predisposing cause; the species of Fusarium, Aspergillus, and Candida are the most frequently isolated organisms. Laboratory methods, such as culture, remains the cornerstone of diagnosis; direct microscopic detection of fungal structures in ocular samples permits a rapid presumptive diagnosis. New approaches, such as serological and molecular methods, have been widely used in recent years. A variety of antifungals have been evaluated in the therapy of this condition. Experimental models would facilitate investigations exploring the pathophysiology, cell biology, genetics, immunology, and therapy of this disease. Conclusions: Fungal infections of the eye continue to be an important cause of ocular morbidity, particularly in the developing world. Understanding ocular infections will improve the outcome of this condition.

Molecular identification, genotyping, and drug susceptibility of the basidiomycetous yeast pathogen Trichosporon isolated from Turkish patients

Deep-seated infections due to Trichosporon species are emerging mycoses that have a very poor prognosis in patients with persistent neutropenia. This study elucidated the mycological characteristics of Trichosporon strains obtained from deep-seated infections in Turkish patients and identified by DNA sequence analysis of intergenic spacer (IGS) region 1 of the rDNA locus. In addition, we genotyped the major causative agent, T. asahii, and evaluated the in vitro drug susceptibility of the isolates. While 87 (81.3%) of the 107 isolates were T. asahii, the remaining 20 were T. faecale (14.0%), T. asteroids (0.9%), T. coremiiforme (0.9%), T. japonicum, (0.9%), T. lactis (0.9%), and a new species (0.9%). In addition to the eight known T. asahii genotypes, one novel genotype was identified. The distribution of the T. asahii genotypes in this study were genotype 1 (79.3%), followed by 5 (8.0%), 3 (6.9%), 6 (3.4%), 4 (1.1%), and 9 (1.1%). Turkish isolates showed low susceptibility to amphotericin B, 5-flucytosine, and fluconazole. Although relatively low minimum inhibitory concentrations (MICs) were found with all drugs, voriconazole appeared to be the most active. The MICs of the non-Trichosporon asahiiTrichosporon species were similar to those of the T. asahii strains. Our findings suggest that Trichosporon species isolated from Turkish patients are more diverse than those reported from other countries.

Effectiveness of Different Cleaning Agents against the Colonization of Candida spp and the in Vitro Detection of the Adherence of These Yeast Cells to Denture Acrylic Surfaces

Purpose The aim of this study is to examine the effect Klorhex and Fittydent, which are used as cleaning agents on the adhesion of Candida on the surfaces of acrylic denture and palatal mucosa. In addition, ability of yeasts to adhere to acrylic strips was evaluated after applying these agents in vitro. Materials and Methods Each group of 15 patients cleaned their dentures with either Klorhex or with Fittydent. The control group cleaned their dentures with water. Results It was found that 62.2% of the patients had colonies of Candida species on their palatal mucosa which was reduced to 51.1% after using these cleaning agents. The colonization rate with Candida spp on their dentures was reduces from 82.2% to 68.8% using these cleaning agents. The mean adhesion value of the Candida strains isolated from the acrylic strips were found to be 75 cell/strip prior to applying the Klorhex and Fittydent and 37.5 cell/strip and 15 cell/strip after applying these agents, respectively. Conclusion These results showed that Klorhex and Fittydent have a certain preventive effect on the colonization rate of Candida spp on the surface of these dentures, the palatal mucosa, as well as on the acrylic strips in vitro.

Use of molecular methods in identification of Candida Species and evaluation of fluconazole resistance

The aim of this study was to evaluate the use of one of the molecular typing methods such as PCR (polymerase chain reaction) following by RFLP (restriction fragment length polymorphism) analysis in the identification of Candida species and then to differentiate the identified azole susceptible and resistant Candida albicans strains by using AP-PCR (arbitrarily primed-polymerase chain reaction). The identification of Candida species by PCR and RFLP analysis was based on the size and primary structural variation of rDNA intergenic spacer regions (ITS). Forty-four clinical Candida isolates comprising 5 species were included to the study. The amplification products were digested individually with 3 different restriction enzymes: HaeIII, DdeI, and BfaI. All the isolates tested yielded the expected band patterns by PCR and RFLP analysis. The results obtained from this study demonstrate that Candida species can be differentiated as C. albicans and non-C. albicans strains only by using HaeIII restriction enzyme and BfaI maintains the differentiation of these non-C. albicans species. After identification Candida species with RFLP analysis, C. albicans strains were included to the AP-PCR test. By using AP-PCR, fluconazole susceptible and resistant strains were differentiated. Nine fluconazole susceptible and 24 fluconazole resistant C. albicans were included to the study. Fluconazole resistant strains had more bands when evaluating with the agarose gel electrophoresis but there were no specific discriminatory band patterns to warrant the differentiation of the resistance. The identification of Candida species with the amplification of intergenic spacer region and RFLP analysis is a practical, short, and a reliable method when comparing to the conventional time-consuming Candida species identification methods. The fluconazole susceptibility testing with AP-PCR seems to be a promising method but further studies must be performed for more specific results.

High incidence of Candida parapsilosis candidaemia in non-neutropenic critically ill patients: epidemiology and antifungal susceptibility.

Abstract The epidemiological and antifungal susceptibility data for 35 episodes of candidemia in intensive care units (ICU) in 2007 were evaluated by prospective active surveillance. The incidence of fungaemia was 39.1 cases per 1000 ICU admissions and 2.85 cases per 1000 patient-days. The crude mortality was 65.7%; 70.8% of the fatalities occurred within 7 days of admission to the ICU. Only 2 species were isolated, Candida parapsilosis (77.1%) and Candida albicans (22.9%). There was no association between mortality and patient characteristics, prior antifungal usage, Candida subspecies or antifungal resistance (p > 0.05). Of the isolates, 5.7% were resistant to fluconazole and caspofungin, and 3.4% to voriconazole and amphotericin B. In molecular analysis of the isolates, 2 clusters of C. parapsilosis in the neurology and anaesthesiology ICUs were detected by randomly amplified polymorphic DNA (RAPD), suggesting a nosocomial transmission. In conclusion, a high incidence and high mortality rate of C. parapsilosis candidaemia were found in the ICUs. An excessive use of invasive procedures, total parenteral nutrition and broad-spectrum antibiotics in the ICUs, combined with a lack of proper infection control measures, may possibly explain the high incidence of C. parapsilosis candidaemia in our hospital.

Slime production and proteinase activity of Candida species isolated from blood samples and the comparison of these activities with minimum inhibitory concentration values of antifungal agents.

Slime and proteinase activity of 54 strains consisting of 19 Candida parapsilosis and 35 C. albicans strains isolated from blood samples were investigated in this study. Ketoconazole, amphothericin B, and fluconazole susceptibility of Candida species were compared with slime production and proteinase activity of these species. For both Candida species, no correlation was detected between the slime activity and minimum inhibitory concentration (MIC) values of the three antifungal agents. For both Candida species no correlation was detected between the proteinase activity and the MIC values of amphothericin B, and fluconazole however, statistically significant difference, was determined between the proteinase activity and MIC values of ketoconazole (p = 0.007). Slime production was determined by using modified Christensen macrotube method and proteinase activity was measured by the method of Staib. Antifungal susceptibility was determined through the guidelines of National Committee for Laboratory Standards (NCCLS M27-A).

Distribution of secreted aspartyl proteinases using a polymerase chain reaction assay withSAP specific primers inCandida albicans isolates

Secreted aspartyl proteinase (Sap) distribution among differentC. albicans isolates was determined usingSAP-specific primers in polymerase chain reaction (PCR) assay.SAP1, SAP2, andSAP3 were detected in 13 of 40 (32.5 %),SAP4 in 38/40 (95 %),SAP5 were detected in 30/40 (75 %),SAP6 in 23/40 (57.5 %) ofC. albicans strains isolated from blood cultures.SAP1-SAP3 were detected in 37 of 40 (92.5 %),SAP4 were detected in 3/40 (7.5 %),SAP5 in 3/40 (7.5 %),SAP6 in 5/40 (12.5 %) ofC. albicans strains isolated from vaginal swab cultures. Sap1, Sap2 and Sap3 isoenzymes were found to be related to the vaginopathic potential ofC. albicans, Sap4, Sap5 and Sap6 isoenzymes were found to be correlated with systemic infections.

Nosocomial fungemia due to Trichosporon asteroides: firstly described bloodstream infection

Trichosporon spp. are oppurtunistic yeasts that cause deep-seated, mucosa-associated, and superficial infections in immunocompromised patients. It is well known that Trichosporon asteroides is mainly responsible of superficial infections and does not cause systemic infections in humans so far. In this study, we present the first case of disseminated infection due to Trichosporon asteroides in an intensive care patient. Yeast colonies were isolated from the specimens of blood, urine, aspiration fluid of the endotracheal tube and catheter tip swabs of the patient. Conventional mycological studies were not adequate for the identification of the isolate to the species level. The genetic identification of the yeast isolate was performed and the DNA sequence of the isolate exactly matched the corresponding sequence of the Trichosporon asteroides rRNA gene from the GenBank DNA database (accession numbers: AB018017, AF075513). Therefore, our isolate was identified as Trichosporon asteroides as a causative agent of deep-seated fungemia.