Orointestinal yeast colonization of paediatric bone marrow transplant recipients: surveillance by quantitative culture and serology

Significance of amplified fragment length polymorphism in identification and epidemiological examination of Candida species colonization in children undergoing allogeneic stem cell transplantation

Candida albicans and non-C. albicans Candida species are increasingly being isolated from patients in high-risk categories, most notably, those who have undergone stem cell transplantation (SCT). Identification of the presence of non-C. albicans Candida species early in the course of the transplant procedure is important, as these species exhibit different sensitivities to the available antifungal treatments and cause mortality at rates that vary from those for C. albicans. Amplified fragment length polymorphism (AFLP) analysis has been shown to be a reliable method of reproducibly identifying medically important Candida species. We investigated the use of serial AFLP analysis of 54 routine surveillance cultures for the identification and epidemiological examination of Candida sp. colonization in five consecutive children undergoing allogeneic SCT. One child became colonized with a C. albicans strain and remained colonized with this strain during the whole admission period. Another child had persistent colonization with a C. albicans strain with striking variations in its AFLP patterns over time, which was considered indicative of microevolution. Candida dubliniensis, Candida lusitaniae, and Saccharomyces cerevisiae were identified in the three remaining patients, with two children being simultaneously and transiently colonized with different species. These findings show that colonization with yeasts during transplantation is a complex and dynamic interaction between the host and the organism(s). In our study three strains from eight separate time points were incorrectly identified as C. albicans by a rapid enzyme test. AFLP analysis of surveillance cultures allowed more accurate and informative epidemiological evaluations of pathogenic yeasts in children during transplantation.

Toxinas killer e produção de enzimas por Candida albicans isoladas da mucosa bucal de pacientes com câncer

Infecções oportunistas da cavidade bucal são primariamente causadas por fungos do gênero Candida e freqüentemente ocorrem em pacientes com câncer que estão sobtratamento quimioterápico e antibacteriano. De 44 amostras coletadas da mucosa oral de pacientes com câncer, observou-se o isolamento de 25 leveduras do gênero Candida em cultivo realizado em ágar Sabouraud-dextrose. Foram identificados Candida albicans em 24 (96%) isolados e C. krusei em 1 (4%). As características fenotípicas das amostras de Candida albicans mostraram que todos os isolados foram fortemente proteolíticos, capazes de produzir fosfolipases e possuíam os biotipos caracterizados como 811(95,8%) e 511 (4,2%) em relação a susceptibilidade às toxinas killer.

Retrospective analysis of yeast colonization and infections in paediatric bone marrow transplant recipients

Sixty-four paediatric patients who underwent allogeneic (n = 35), autologous (n = 28) or syngeneic (n = 1) bone marrow transplantation (BMT) between 1992 and 1994 were evaluated retrospectively. As antifungal prophylaxis, all patients received amphotericin B tablets and 62 of 64 (96.9%) received oral fluconazole. Weekly surveillance cultures revealed fungal colonization in 35 patients (54.7%). Six patients (9.4%) were colonized before BMT only, 17 (26.6%) after BMT only and 12 (18.8%) both before and after BMT. Candida albicans was the most frequently isolated fungus [21 of 46 fungal isolates (45.7%)], followed by C. glabrata [14 isolates (30.4%)]. Non-albicans species of Candida were most frequently isolated after BMT from the faeces, often in high numbers. Autologous marrow recipients had a higher fungal colonization rate both before and after BMT than allogeneic marrow recipients. One patient suffered from invasive pulmonary aspergillosis after BMT. No fungaemias or deep-seated yeast infections were observed. Six of the seven patients who had to be treated with intravenous amphotericin B because of antibiotic-refractory fever had undergone autologous BMT. Multivariate analysis of various parameters showed only pre-BMT yeast colonization to be independently associated with post-BMT colonization. Thus, systemic mycoses occurred only rarely in this study population; however yeast colonization after BMT (especially with non-albicans species) was a frequent event in spite of double prophylaxis with oral amphotericin B and fluconazole.

Clinical and laboratory diagnosis of invasive candida infection in neutropenic patients

Cancer patients, especially those with acute leukaemia, represent a group that has the greatest risk for deep fungal infection. Almost no cases were seen before the advent of modern chemotherapy, and prior to the availability of antibacterial agents, less than 5% of patients with acute leukaemia died of fungal infection. These infections are now responsible for 40% or more of the deaths at some institutions. Candida species continues to be the most common fungal pathogen. Rapid and specific diagnosis of invasive candiosis enabling early effective therapy is therefore an important measure for reducing mortality in patients. Here the current status of clinical and laboratory diagnosis of invasive candida infection in neutropenic patients is discussed and recommendations made as to future development programmes.

Orointestinal yeast colonization of paediatric oncologic patients during antifungal prophylaxis: results of quantitative culture and Candida serology and comparison of three polyenes

The orointestinal yeast colonization of 46 children with newly diagnosed malignancies was studied prospectively and longitudinally with quantitative cultures during remission induction chemotherapy. The initial colonization rate was 24%; only 28% of the patients remained free of yeasts during their entire treatment although all of them continuously received oral polyenes as antifungal prophylaxis. A randomized comparison of natamycin (suspension, lozenges), nystatin (suspension) and amphotericin B (suspension, lozenges) failed due to serious problems with patient compliance. Natamycin was best accepted by the patients and natamycin lozenges were the most efficacious drug in the oral cavity. The effectivity of the suspensions of nystatin and amphotericin B was similar; both were equally efficacious in the oral cavity and the gut. Assessment of faecal polyene concentrations by HPLC showed the highest results for amphotericin B (mean 6808 microgram(-1)). Regularly performed Candida serology (indirect haemagglutination, indirect immunofluorescence and immunodiffusion precipitation) revealed significant titre increases in 63% of the patients. In six cases, the synopsis of clinical picture, culture and serology strongly suggested systemic yeast invasion.