Update on invasive candidiasis

The underestimated problem of oral Candida colonization-An observational pilot study in one nursing home

Objectives

Older people are at increased risk of intraoral yeast colonization. In this observational case series, we assessed Candida colonization among nine nursing home residents to investigate possible correlations with their individual characteristics, general health parameters, and oral care. We also described the effect of professional dental cleaning (PDC) including prosthesis cleaning on colonization cases.

Materials and methods

General clinical and oral health was assessed in nine residents, and samples were taken from six oral mucosa sites or prosthetic surfaces. PDC was performed to achieve macroscopically clean results, and residents were re-examined 2 weeks later.

Results

We found that six residents were intraorally colonized with Candida albicans; four also had Candida glabrata. Prostheses were particularly infected. Dementia, multimorbidity, and presence of prostheses reduced oral hygiene ability; requiring assistance for oral hygiene care was a risk indicator for Candida colonization. PDC reduced C. albicans (at the expense of increased C. glabrata) but was not optimal for maintaining Candida reduction.

Conclusion

In this pilot study, Candida colonization is prevalent among nursing home residents, especially those with cognitive impairment, multimorbidity, or reduced oral hygiene capacity. Potential negative effects on general health necessitate diagnostic and therapeutic guidelines. PDC alone did not maintain the reduction in Candida colonization; additional methods for daily oral care are necessary.

Detection of fungal DNA in lysis-centrifugation blood culture for the diagnosis of invasive candidiasis in neonatal patients

We report data concerning the detection of fungal DNA directly from lysis-centrifugation blood culture to assess its value in the detection of fungaemia in 86 of the 347 patients admitted to the neonatal intensive-care unit between January 2009 and December 2010. The sensitivity and specificity of the PCR were 87.5% and 98.5%, respectively, with a positive predictive value of 93.3% and a negative predictive value of 97.1%. Detection of fungal DNA directly from blood culture Isolator 1.5 microbial tubes, without prior cultivation, is a promising approach for the rapid detection of Candida spp. in neonates with suspected candidaemia.

Diagnosis and therapy of Candida infections: joint recommendations of the German Speaking Mycological Society and the Paul-Ehrlich-Society for Chemotherapy

Invasive Candida infections are important causes of morbidity and mortality in immunocompromised and hospitalised patients. This article provides the joint recommendations of the German-speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMyKG) and the Paul-Ehrlich-Society for Chemotherapy (PEG) for diagnosis and treatment of invasive and superficial Candida infections. The recommendations are based on published results of clinical trials, case-series and expert opinion using the evidence criteria set forth by the Infectious Diseases Society of America (IDSA). Key recommendations are summarised here: The cornerstone of diagnosis remains the detection of the organism by culture with identification of the isolate at the species level; in vitro susceptibility testing is mandatory for invasive isolates. Options for initial therapy of candidaemia and other invasive Candida infections in non-granulocytopenic patients include fluconazole or one of the three approved echinocandin compounds; liposomal amphotericin B and voriconazole are secondary alternatives because of their less favourable pharmacological properties. In granulocytopenic patients, an echinocandin or liposomal amphotericin B is recommended as initial therapy based on the fungicidal mode of action. Indwelling central venous catheters serve as a main source of infection independent of the pathogenesis of candidaemia in the individual patients and should be removed whenever feasible. Pre-existing immunosuppressive treatment, particularly by glucocorticosteroids, ought to be discontinued, if feasible, or reduced. The duration of treatment for uncomplicated candidaemia is 14 days following the first negative blood culture and resolution of all associated symptoms and findings. Ophthalmoscopy is recommended prior to the discontinuation of antifungal chemotherapy to rule out endophthalmitis or chorioretinitis. Beyond these key recommendations, this article provides detailed recommendations for specific disease entities, for antifungal treatment in paediatric patients as well as a comprehensive discussion of epidemiology, clinical presentation and emerging diagnostic options of invasive and superficial Candida infections.

Retinal lesions as clues to disseminated bacterial and candidal infections: frequency, natural history, and etiology

Invasive bacterial and candidal infections are known to involve the retina, but the natural history of the retinal lesions and the utility of ophthalmologic consultation in the critical care setting as a diagnostic tool are not well understood. We 1) performed weekly funduscopic examinations on 77 medical and surgical patients in intensive care units (ICUs), 2) analyzed results of serial ocular examinations in 180 non-neutropenic patients with candidemia, and 3) reviewed the English literature on the association of retinal lesions with disseminated bacterial or candidal infection (DBCI). We found that 15 (19%) of the ICU patients had retinal lesions consistent with DBCI. Of these 15, 1 had clearly sepsis-related retinal lesions, while 13 (87%) had 1 or more systemic disease that could have explained their retinal findings (6 diabetic retinopathy; 2 human immunodeficiency virus infection/acquired immunodeficiency syndrome (HIV/AIDS) retinopathy; 2 hypertensive retinopathy; 1 hemolytic uremic syndrome, and 1 leukemia). Multivariate analysis revealed that systemic disease (odds ratio 8.37, 95% confidence intervals: 3.24-21.56) independently correlated with the presence of retinal lesions while DBCI, trauma, hyperalimentation, and transfusion of blood products were not independently predictive in any analysis. Twenty of the 180 (15%) candidemic patients had retinal lesions. Two (1%) had classic 3-dimensional white lesions with vitreal extension, and 5 (2.7%) had chorioretinal lesions without vitreal haziness. Notably, 10% of patients had superficial retinal hemorrhages and/or cotton wool spots that could have been due to either candidemia or a systemic disease (diabetes, hypertension, renal failure, closed head trauma). Concurrent bacteremia occurred in 3 of the 27 patients with eye lesions. Retinal lesions resolved in a mean of 33 days. None of the patients had symptoms at the time of the retinal finding. We found 3 studies that prospectively assessed retinal lesions in bacteremic patients. The frequency of retinal lesions in these series varied from 12% to 26%, with the most common lesions being cotton wool spots followed by superficial retinal hemorrhages. White-centered hemorrhages were seen in about 15% +/- 2 of bacteremic patients. Five studies prospectively evaluated candidemic patients for Candida endophthalmitis. These studies observed rates from 0% to 78% for lesions consistent with candidal endophthalmitis. Most studies performed recently found that nonspecific lesions such as cotton wool spots or superficial retinal hemorrhages occurred with a frequency of 11% to 20%. The availability of less toxic antifungal agents, more frequent use of empirical therapy, and the trend to early treatment may be altering the frequency of this complication. Observation of a classic 3-dimensional retina-based vitreal inflammatory process is virtually diagnostic of endogenous endophthalmitis due to Candida spp., but such lesions are relatively uncommon. Conversely, nonspecific lesions that could be due to bacterial or candidal endophthalmitis (cotton wool spots, retinal hemorrhages, and Roth spots) are seen frequently. These lesions are most often due to an underlying systemic disease rather than an infection. Serial examinations provide the best evidence that a given lesion is due to an intercurrent infection. The current low rate of vitreal extension of retinal process appears to be due to the high rate of empirical or therapeutic use of antifungal agents in high-risk patient groups. Ophthalmoscopy should be performed in patients with known candidemia. However, ophthalmoscopic examination seems to have little value in assisting with the discovery of occult disseminated candidiasis or bacterial infection.

Antifungal susceptibility testing: practical aspects and current challenges

Development of standardized antifungal susceptibility testing methods has been the focus of intensive research for the last 15 years. Reference methods for yeasts (NCCLS M27-A) and molds (M38-P) are now available. The development of these methods provides researchers not only with standardized methods for testing but also with an understanding of the variables that affect interlaboratory reproducibility. With this knowledge, we have now moved into the phase of (i) demonstrating the clinical value (or lack thereof) of standardized methods, (ii) developing modifications to these reference methods that address specific problems, and (iii) developing reliable commercial test kits. Clinically relevant testing is now available for selected fungi and drugs: Candida spp. against fluconazole, itraconazole, flucytosine, and (perhaps) amphotericin B; Cryptococcus neoformans against (perhaps) fluconazole and amphotericin B; and Aspergillus spp. against (perhaps) itraconazole. Expanding the range of useful testing procedures is the current focus of research in this area.

Discovery of novel antifungal (1,3)-beta-D-glucan synthase inhibitors

The increasing incidence of life-threatening fungal infections has driven the search for new, broad-spectrum fungicidal agents that can be used for treatment and prophylaxis in immunocompromised patients. Natural-product inhibitors of cell wall (1,3)-beta-D-glucan synthase such as lipopeptide pneumocandins and echinocandins as well as the glycolipid papulacandins have been evaluated as potential therapeutics for the last two decades. As a result, MK-0991 (caspofungin acetate; Cancidas), a semisynthetic analogue of pneumocandin B(o), is being developed as a broad-spectrum parenteral agent for the treatment of aspergillosis and candidiasis. This and other lipopeptide antifungal agents have limited oral bioavailability. Thus, we have sought new chemical structures with the mode of action of lipopeptide antifungal agents but with the potential for oral absorption. Results of natural-product screening by a series of newly developed methods has led to the identification of four acidic terpenoid (1,3)-beta-D-glucan synthase inhibitors. Of the four compounds, the in vitro antifungal activity of one, enfumafungin, is comparable to that of L-733560, a close analogue of MK-0991. Like the lipopeptides, enfumafungin specifically inhibits glucan synthesis in whole cells and in (1,3)-beta-D-glucan synthase assays, alters the morphologies of yeasts and molds, and produces a unique response in Saccharomyces cerevisiae strains with point mutations in FKS1, the gene which encodes the large subunit of glucan synthase.

Novel strategies for treating candidiasis

In this review the recent achievements in the field of chemotherapy and immunotherapy of candidiasis are outlined. The current limitations of chemotherapeutic approaches and the lack of well defined preventive tools and strategies make it imperative to exploit the potential of novel immunotherapeutic venues. In this prospect the rather extensive work performed on cytokine patterns in experimental models and the upsurge of antibodies as one mechanism of anti-Candida protection raises great promise for the clinical use of immunotherapy possibly in conjunction with chemotherapy to improve the fight against this increasingly prevalent human opportunistic infection.