Variations in fluconazole susceptibility and DNA subtyping of multiple Candida albicans colonies from patients with AIDS and oral candidiasis suffering one or more episodes of infection

Assessment of saliva and oral candidiasis levels 12, 24 and 36 months after radiotherapy in patients with head and neck cancer

INTRODUCTION

Hyposalivation is a serious complication during radiotherapy (RT) and it is one of the major risk factors for the presence of candidiasis. The aim of this study was to evaluate the salivary hypofunction during the different stages of RT, analysing its connection with the presence of candidiasis.

MATERIAL AND METHODS

A retrospective study was performed in 83 patients who had been diagnosed with head and neck tumours and who were undergoing RT treatment. Their salivary function was clinically analysed throughout the course of the RT treatment (before, during and after treatment) by means of the whole saliva test (WST), both unstimulated (WST-I) and stimulated (WST-II), and its relationship with candidiasis was evaluated using culture-based methods.

RESULTS

The WST-I before RT was 37.24±17.36mm and the WST-II was 60.70±30.98mm, with 47% of patients testing positive for candidiasis. The prevalence of candidiasis increased up to 55.8% during RT and it returned to similar pre-RT levels at the end of treatment (45.2%). A statistical significant relationship was found between low WST-I and candidiasis in the 1st (13.58 vs 20.78mm), 3rd (18.06 vs 24.36mm), 6th (16.83 vs 24.5) and 12th (16 vs 28.74mm) months after RT; and this relationship was also detected for WST-II in the 1st (24.73 vs 41.26mm) and 3rd (27.71 vs 39.91mm) months after RT. Female sex was identified as an independent associated risk factor for mild hyposalivation before RT (OR=6.50, CI: 95% 1.77-23.93, p=0.005) and glandular hypofunction (OR=3.01, CI: 95% 1.12-8.10, p=0.029).

DISCUSSION

There is a clear relation between hyposalivation and the presence of candidiasis during and after RT. Larger studies must be performed in order to further elucidate this effect.

Genotyping and antifungal susceptibility testing of multiple Malassezia pachydermatis isolates from otitis and dermatitis cases in pets: is it really worth the effort?

A total of 216 colonies of Malassezia pachydermatis from 28 cases of fungal otitis or dermatitis in pets were genotyped by M13 fingerprinting and tested for antifungal susceptibility. A huge genetic diversity was found (157 M13 types in total), with all animals having a polyclonal pattern of infection (5.4 ± 1.5 genotypes/sample). Furthermore, analysis of molecular variance (AMOVA) revealed that most genetic diversity (44%) was found at the within sample level. In contrast, variability in antifungal susceptibility among isolates from the same sample was less important, with different M13 types displaying in most cases identical or very similar MIC results. Most isolates displayed high in vitro susceptibility to amphotericin B, terbinafine and all azoles tested except fluconazole, for which MIC values were always ≥4 μg/ml and a 26.9% of isolates displayed values ≥32 μg/ml. We conclude that although characterization of multiple yeast isolates results in a considerable increase in laboratory workload and expenses, it may help to get a better understanding of the epidemiology of M. pachydermatis in a given patient population.

Simultaneous infection of human host with genetically distinct isolates of Paracoccidioides brasiliensis

This study is the first report on genetic differences between isolates of Paracoccidioides brasiliensis from a single patient. We describe a simultaneous infection with genetically distinct isolates of P. brasiliensis in a patient with chronic paracoccidioidomycosis. The clinical isolates were obtained from lesions in different anatomical sites and were characterised by random amplified polymorphic DNA (RAPD) analysis. The RAPD technique can be helpful for distinguishing between clinical isolates. Different random primers were used to characterise these clinical isolates. The RAPD patterns allowed for differentiation between isolates and the construction of a phenetic tree, which showed more than 28% genetic variability in this fungal species, opening new possibilities for clinical studies of P. brasiliensis. Based on these results and preliminary clinical findings, we suggest that different genotypes of P. brasiliensis might infect the same patient, inducing the active form of the disease.

Potential role of high molecular weight hyaluronan in the anti-Candida activity of human oral epithelial cells

Candida albicans is both a commensal and a pathogen in the oral mucosa. Previous studies have indicated that epithelial cell-associated carbohydrate moiety can inhibit C. albicans growth. In the present study, the mechanisms by which epithelial cells inhibit Candida growth were studied by examining the effect of hyaluronan (HA). A coculture of C. albicans and KB cells or COS-7 cells inhibited in vitro growth of the fungus by 50-87% at an effector-to-target (E:T) ratio of 80:1. Removing extracellular HA by hyaluronidase caused a significant decrease in the anti-Candida activity of the cells. In addition anti-Candida activity was observed at 1 micro g/ml HA (2000 kDa). The antifungal activity of extracellular HA was further studied by transiently transfecting COS-7 cells with human HSA1, HSA2, or HSA3 in order to produce high levels of extracellular HA. All of the transfectants inhibited C. albicans growth in vitro by 51-65% compared to 38% inhibition by the vector control (P<0.05). These results suggest that the anti-Candida activity of epithelial-cells is mediated by extracellular HA.

Complicações bucais da radioterapia em cabeça e pescoço

A radioterapia é uma forma terapêutica amplamente utilizada para o tratamento das neoplasias malignas da cabeça e pescoço. Porém, altas doses de radiação em extensos campos que irão incluir a cavidade bucal, maxila, mandíbula e glândulas salivares freqüentemente resultam em diversas reações indesejadas. Dentre as complicações da radioterapia estão a mucosite, candidose, disgeusia, cárie por radiação, osteorradionecrose, necrose do tecido mole e xerostomia. OBJETIVO: O objetivo deste artigo é fazer uma breve revisão das reações adversas que podem ser detectadas durante o tratamento radioterápico em região de cabeça e pescoço. MÉTODO: A literatura pertinente que trata do assunto foi revisada. FORMA DE ESTUDO: Revisão de literatura. RESULTADOS: A radioterapia ainda está associada a diversas reações adversas, que afetam de forma significativa a qualidade de vida dos pacientes. CONCLUSÕES: O tratamento multidisciplinar, incluindo a equipe médica, o cirurgião-dentista, o fonoaudiólogo, o nutricionista e o psicólogo é a melhor alternativa para minimizar ou mesmo prevenir tais complicações.

Oral complications of radiotherapy in the head and neck

Radiotherapy is a treatment modality largely used for head and neck malignancies. However, high doses of radiation in large areas, including the oral cavity, maxilla, mandible and salivary glands may result in several undesired reactions. Mucositis, candidosis, disgeusia, radiation caries, osteoradionecrosis, soft tissue necrosis and xerostomia are some of radiotherapy's complications.

Aim

The aim of this study is to briefly review the side effects that may be seen in the oral cavity during or after radiotherapy treatment in the head and neck region.

Basic method used

Review of relevant literature.

Study design

Literature review.

Results

Radiotherapy is still associated with several side effects, significantly affecting patients’ quality of life.

Conclusions

A multidisciplinary treatment, including physicians, dentists, speech therapits, nutritionists, and psychologists, is the best alternative to minimize, or even prevent such reactions.

Immunopathogenesis of oropharyngeal candidiasis in human immunodeficiency virus infection

Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4(+) cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8(+) T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.

Twelve years of fluconazole in clinical practice: global trends in species distribution and fluconazole susceptibility of bloodstream isolates of Candida

We determined the species distribution and in-vitro susceptibility of 6082 bloodstream infection (BSI) isolates of Candida spp. collected from 250 medical centres in 32 nations over a 10-year period from 1992 through 2001. The species included 3401 C. albicans, 984 C. glabrata, 796 C. parapsilosis, 585 C. tropicalis, 153 C. krusei, 67 C. lusitaniae, 48 C. guilliermondii, 10 C. famata, 10 C. kefyr, six C. pelliculosa, five C. rugosa, four C. lipolytica, three C. dubliniensis, three C. inconspicua, two C. sake and one isolate each of C. lambica, C. norvegensis and C. zeylanoides. Minimum inhibitory concentration determinations were made using the National Committee for Clinical Laboratory Standards reference broth microdilution method. Variation in the rank order and frequency of the different species of Candida was observed over time and by geographic area. The proportion of BSI due to C. albicans and C. glabrata increased and C. parapsilosis decreased over time in Canada, the USA and Europe. C. glabrata was an infrequent cause of BSI in Latin America and the Asia-Pacific region. Very little variation in fluconazole susceptibility was observed among isolates of C. albicans, C. tropicalis and C. parapsilosis. These species accounted for 78% of all BSI and remained highly susceptible (91-100% susceptible) to fluconazole from 1992 to 2001 irrespective of geographic origin. The prevalence of fluconazole resistance among C. glabrata isolates was variable both over time and among the various countries and regions. Resistance to fluconazole among C. glabrata isolates was greatest in the USA and varied by US census region (range 0-23%). These observations are generally encouraging relative to the sustained usefulness of fluconazole as a systemically active antifungal agent for the treatment of candida BSI.

Oropharyngeal candidiasis caused by non-albicans yeast in patients receiving external beam radiotherapy for head-and-neck cancer

PURPOSE

To characterize non-albicans Candida oral infections in patients with head-and-neck cancer receiving external beam radiotherapy (EBRT) with or without concurrent chemotherapy.

METHODS AND MATERIALS

Thirty-seven patients with head-and-neck cancer received EBRT in 2.0-Gy daily fractions to a median dose of 60.4 Gy (range 38-82.8, mean 64.6). They were followed for oropharyngeal candidiasis (OPC) confirmed by positive examination, positive KOH smear, and/or positive swab or swish culture. Samples were identified and plated on chromogenic media to identify non-albicans yeasts. Colonies were plated on Sabouraud dextrose slants for microdilution antifungal susceptibility testing to fluconazole. DNA typing, including karyotyping, restriction fragment length polymorphism analysis, and Southern blot hybridization with the moderately repetitive Ca3 probe, was performed on selected isolates to confirm individual species.

RESULTS

Of the 37 patients, 10 (27%) developed OPC, and 26 (70.3%) displayed Candida carriage state. The median EBRT dose at time of positive culture was 22.5 Gy and at time of OPC was 28.6 Gy. Of the 6 patients receiving chemotherapy and EBRT, 4 (66%) developed OPC at median dose of 27.6 Gy. Three (8%) of 37 patients were infected with non-albicans Candida, and 3 (30%) of all 10 infections were caused by these organisms.

CONCLUSION

Non-albicans Candida is emerging as a relatively common cause of OPC in head-and-neck cancer patients. Chromogenic media are helpful to screen these infections. Our data also suggest a greater likelihood of developing OPC in patients receiving concomitant chemotherapy and EBRT.

'Genotypic shuffling' of sequential clones of Candida albicans in HIV-infected individuals with and without symptomatic oral candidiasis

Although HIV-infected individuals harbour multiple strains of oral Candida albicans, little is known of their micro-evolution over time. Therefore, a prospective study was conducted with 16 HIV-infected ethnic Chinese individuals with and without symptoms of oropharyngeal candidiasis to evaluate the genotype distribution of oral C. albicans isolates during HIV disease progression. Oral-rinse samples were obtained from all individuals and up to five C. albicans colonies were selected for each visit, over a 12 month period of multiple visits. After identification of isolates using standard mycological criteria, the genetic similarities of yeast isolates within and between sequential clones of C. albicans were assessed by DNA fingerprinting through random amplification of polymorphic DNA (RAPD). The results of RAPD gel profiles and the lineage of each isolate were further analysed using commercially available software. RAPD studies revealed the prevalence of up to 14 different genotypes per individual during the study period, with multiple genotypes isolated simultaneously from a single oral rinse. Computer analysis of RAPD profiles revealed that yeasts isolated over sequential visits from symptomatic individuals demonstrated a striking level of relatedness compared with isolates from asymptomatic individuals. Genetically identical C. albicans strains also formed 'loosely' connected subclusters that overlapped multiple visits, implying genetic 'shuffling' in these isolates during disease progression. These data point to varying evolutionary genetic trends in C. albicans associated with symptomatic oral candidiasis and asymptomatic carriage in HIV disease.

Prospective epidemiologic analysis of triazole-resistant nosocomial Candida glabrata isolated from patients at a comprehensive cancer center

OBJECTIVE

The emergence of Candida glabrata infections among patients with compromised immunity has become a serious concern, especially at centers caring for individuals with cancer.

METHODS

During a prospective evaluation of Candida species associated with either clinically significant colonization or infection, 26.9% of C. glabrata isolates showed in vitro resistance to fluconazole (MIC of > or = 64 microg/ml).

RESULTS

Antifungal susceptibility profiles and genetic fingerprinting analysis performed by randomly amplified polymorphic DNA (RAPD) techniques confirmed low-probability of phenotypic and genotypic relatedness among nosocomial C. glabrata isolates.

CONCLUSIONS

Presence of polyclonal strains of C. glabrata in patients at our hospital was probably related to selection of resistant yeasts from environmental pool rather than monoclonal expansion or clustering of multi-drug resistant C. glabrata in high-risk patients.

Molecular heterogeneity of fluconazole-resistant and -susceptible oral Candida albicans isolates within a single geographic locale

The emergence of drug-resistant Candida albicans in immunocompromised patients is common. A disconcerting aspect of this phenomenon is the rapid emergence of C. albicans strains that are resistant to a widely used azole drug, fluconazole (FLZ). To understand the origin of FLZ-resistant yeast isolates, we investigated molecular profiles of 20 geographically related oral C. albicans isolates using three genotyping methods: randomly amplified polymorphic DNA-PCR, with six different primers (OBU1, OBU2, OBU3 RSD6, RSD11 and RSD12); electrophoretic karyotyping by pulsed-field gel electrophoresis; and HinfI restriction fragment analysis. Of the 20 isolates studied, 10 were FLZ- resistant and originated from patients with oral candidosis with a history of FLZ therapy, and the remainder were FLZ susceptible from individuals with oral candidosis, but without a history of FLZ therapy. A composite genotype was generated for each strain by combining molecular types derived from the three independent molecular methods. The composite profiles indicated genetic diversity amongst both the FLZ-resistant as well as -sensitive isolates, and no specific features emerged distinguishing the drug-resistant and -sensitive groups. These observations cast doubt on the theory of a clonal origin of FLZ-resistant C. albicans isolates.

Resistance of Candida species to antifungal agents: molecular mechanisms and clinical consequences

Candida albicans and related species pathogenic for man become resistant to antifungal agents, in particular triazole compounds, by expression of efflux pumps that reduce drug accumulation, alteration of the structure or concentration of antifungal target proteins, and alteration of membrane sterol composition. The clinical consequences of antifungal resistance can be seen in treatment failures in patients and in changes in the prevalences of Candida species causing disease. These effects were seen unequivocally in HIV-infected patients with oropharyngeal candida infections, but their incidence has decreased dramatically with the introduction of highly active antiretroviral therapy. The evidence for similar emergence of antifungal-resistant yeast strains and species in other types of candida infections is confounded by non-standardised susceptibility testing methods and definitions of a resistant fungal isolate. Recent large-scale surveys of yeasts isolated from blood cultures, based on standardised methodology and resistance definitions, do not support the view that antifungal resistance in pathogenic yeasts constitutes a significant or growing therapeutic problem.

Carriage frequency, intensity of carriage, and strains of oral yeast species vary in the progression to oral candidiasis in human immunodeficiency virus-positive individuals

Candida samples were taken over a period of 2 years from 54 human immunodeficiency virus (HIV)-positive asymptomatic subjects to evaluate changes in yeast carriage, intensity of carriage, and genotype over time. Overall, we found that HIV-positive patients with CD4(+)-cell counts of between 200 and 400/microl had significantly more yeast colonization than healthy control subjects. Of the 54 patients, 11 developed thrush. We found that intensity of carriage in these 11 patients increased significantly in the progression from asymptomatic yeast carrier to an episode of oral thrush. Also, the most common yeast species isolated was Candida albicans; however, we did see a number of patients harboring multiple species at the same time. Using the C. albicans-specific probe Ca3, we found that 54% (n = 6) of the 11 patients who developed thrush maintained genetically similar strains throughout the study period, with minor genetic variations in all patients except one. Forty-six percent of these patients had either multiple strains throughout the study period (n = 2), strain replacement (n = 1), or species replacement (n = 2). Of the patients who had multiple strains, one (I4) was infected by two different strains of Candida dubliniensis distinguished by a recently developed species-specific probe. These results suggest that commensal strains colonizing HIV-positive individuals can undergo alterations prior to producing an episode of thrush.

Antifungal effects of lysozyme and lactoferrin against genetically similar, sequential Candida albicans isolates from a human immunodeficiency virus-infected southern Chinese cohort

A variety of innate defense factors in saliva such as lysozyme and lactoferrin contribute to mucosal protection and modulate Candida populations in the oral cavity. It is also known that in human immunodeficiency virus (HIV)-infected individuals significant variations in the concentrations of lysozyme and lactoferrin in saliva occur during disease progression. Therefore, the aim of this study was to determine the in vitro susceptibility to human lactoferrin and hen egg white lysozyme of genotypically similar oral Candida albicans isolates obtained from six HIV-infected ethnic Chinese during sequential visits over a 12-month period. The similarity of the genotypes (50 in total) was evaluated using a randomly amplified polymorphic DNA assay. A blastospore viability assay was performed to evaluate the sensitivity of the organisms to lysozyme and lactoferrin. Exposure to physiological concentrations of either lysozyme (30 microg/ml) or lactoferrin (20 microg/ml) caused a rapid loss of viability among all isolates to a varying extent. None of the sequential C. albicans isolates demonstrated significant differences in sensitivity to either protein from one visit to the next; similar results were noted when the different genotypes from the same individual were compared. On Spearman correlation analysis of two genotypes that were sequentially isolated from a single patient, a significant negative correlation between lysozyme (r = -0.88; P < 0.02) (but not lactoferrin) resistance and the duration of HIV disease was seen. These results imply that a minority of C. albicans isolates that persist intraorally in individuals with HIV disease develop progressive resistance to innate salivary antifungal defenses such as lysozyme, possibly as an adaptive response. However, the vast majority of the Candida isolates appear to succumb to these nonspecific host immune mediators abundantly present in the oral environment.

Molecular epidemiology of Candida albicans strains isolated from the oropharynx of HIV-positive patients at successive clinic visits

Candida albicans strain diversity and fluconazole resistance were prospectively analyzed in oral strains from 29 adult human immunodeficiency virus (HIV)-positive patients followed for > 1 year who had five or more culture-positive clinic visits. Molecular typing consisted of genomic blots probed with the Ca3 repetitive element. Sixteen patients had one or more episodes of oropharyngeal candidiasis (OPC), 12 (75%) maintained the original genotype, whereas the remaining four patients had a succession of 2-3 genotypes. The original genotype, either alone or mixed with another strain or with non-C. albicans Candida spp., was recovered from oral lesions in 13 of 15 evaluable (86.7%) patients. C. dubliniensis was the infecting yeast in the remaining two patients. Different patterns of fluconazole resistance occurred in three OPC patients. One patient's infecting strain became less susceptible. A second patient was infected with a resistant genotype and a progressively more susceptible minor genotype variant. C. dubliniensis isolates from the third patient varied in susceptibility. Thirteen colonized patients who never developed OPC harbored a greater variety of C. albicans genotypes (2-6) than their infected counterparts (P = 0.35). OPC patients maintained their original endogenous C. albicans strains for prolonged periods, whether or not they demonstrated decreased in vitro susceptibility to fluconazole. The adaptation and maintenance of an endogenous C. albicans strain within its host may be linked to as yet uncharacterized factors.

Subtyping and antifungal susceptibilities of Candida spp. in the intensive care unit of a Greek general hospital

This study identified the Candida spp., susceptibility to antifungal agents and the prevailing Candida albicans subtypes responsible for infections or colonization of 42 patients in the ICU over a 6-month period. Most isolates were C. albicans (66.1%) and Candida tropicalis (28.3%) all of which were susceptible in vitro to antifungal agents. Subtypes of the C. albicans isolates were identified by pulsed field gel electrophoresis Sfi I chromosomal digests. Two major C. albicans subtypes were identified, whereas subtype heterogeneity was found among strains of Candida glabrata and C. tropicalis. Sfi I PFGE restriction patterns were able to discriminate between sub-populations of C. albicans isolates, clustering them into distinct, epidemiologically congruous groups.

Epidemiological typing of Candida albicans from bloodstream infections by restriction enzyme analysis

Candida albicans blood culture isolates (n = 142) from 130 patients treated in 7 acute care hospitals in Southern Finland between 1986 and 1995 were typed by restriction enzyme analysis (REA) with EcoRI and MspI. REA revealed 118 distinct DNA types: 13 were detected in > 1 patient and 105 DNA types were unique. Patients with identical DNA types were not temporally or geographically clustered. Among 11 patients with more than 1 C. albicans isolate during 1 episode of fungemia the DNA type remained the same, except in 1 patient. These results indicate that REA is a powerful tool for the epidemiological typing of C. albicans infections.

DNA fingerprinting of serial Candida albicans isolates obtained during itraconazole prophylaxis in patients with AIDS

During a randomized double-blind placebo-controlled study testing the efficacy of itraconazole for prophylaxis of systemic and mucosal fungal infections in patients with acquired immune deficiency syndrome, 298 patients were enrolled with 295 evaluable. Of those, 46 patients were considered prophylaxis failures because of recurrent oral or esophageal candidiasis. Oropharyngeal fungal cultures were taken at the time of suspected thrush or Candida esophagitis, but not at baseline. All of the Candida spp. isolates were cultured on CHROMagar Candida medium then identified using API 20 AUX strips. Antifungal susceptibility testing was performed following the National Committee for Clinical Laboratory Standards M-27A guidelines. Sequential isolates were genotyped using randomly amplified polymorphic DNA. Polymerase chain reaction fingerprints were generated using two repetitive sequence primers, (GGA)7 and (GACA)4. The study group consisted of 23 patients, nine from the itraconazole arm and 14 from the placebo arm, who were prophylaxis failures and had more than two C. albicans isolates. Five of 23 had isolates showing a > or =4-fold reduction in susceptibility; four of these patients were in the itraconazole prophylaxis arm and one was in the placebo arm. Three of the five had yeast isolations showing changes in banding patterns over time. Such changes may indicate genetic changes in the same strain that could be linked to acquired resistance to itraconazole, or acquisition of a new strain, or emergence of a previously minor component of the original population.

Clonal and spontaneous origins of fluconazole resistance in Candida albicans

The genotypes and susceptibilities to fluconazole of 78 strains of the human pathogenic yeast Candida albicans were compared. The strains comprised two sets of samples from Durham, N.C.: one from patients infected with the human immunodeficiency virus (HIV) and the other from healthy volunteers. For each strain, the MIC of fluconazole was determined by the standard National Committee for Clinical Laboratory Standards protocol. Genotypes were determined by PCR fingerprinting with five separate primers. The analysis revealed little evidence for genotypic clustering according to HIV status or body site. However, a small group of fluconazole-resistant strains isolated from patients infected with HIV formed a distinct cluster. In addition, two fluconazole-resistant strains were isolated from individuals who never took fluconazole, one from a patient infected with HIV and the other from a healthy person. The results suggest both clonal and spontaneous origins of fluconazole resistance in C. albicans.

Epidemiology of oropharyngeal Candida colonization and infection in patients receiving radiation for head and neck cancer

Oral mucosal colonization and infection with Candida are common in patients receiving radiation therapy for head and neck cancer. Infection is marked by oral pain and/or burning and can lead to significant patient morbidity. The purpose of this study was to identify Candida strain diversity in this population by using a chromogenic medium, subculturing, molecular typing, and antifungal susceptibility testing of clinical isolates. These results were then correlated with clinical outcome in patients treated with fluconazole for infection. Specimens from 30 patients receiving radiation therapy for head and neck cancer were cultured weekly for Candida. Patients exhibiting clinical infection were treated with oral fluconazole. All isolates were plated on CHROMagar Candida and RPMI medium, subcultured, and submitted for antifungal susceptibility testing and molecular typing. Infections occurred in 27% of the patients and were predominantly due to Candida albicans (78%). Candida carriage occurred in 73% of patients and at 51% of patient visits. Yeasts other than C. albicans predominated in carriage, as they were isolated from 59% of patients and at 52% of patient visits. All infections responded clinically, and all isolates were susceptible to fluconazole. Molecular typing showed that most patients had similar strains throughout their radiation treatment. One patient, however, did show the acquisition of a new strain. With this high rate of infection (27%), prophylaxis to prevent infection should be evaluated for these patients.

The use of fluconazole and itraconazole in the treatment of Candida albicans infections: a review

Candida albicans is responsible for most fungal infections in humans. Fluconazole is well established as a first-line management option for the treatment and prophylaxis of localized and systemic C. albicans infections. Fluconazole exhibits predictable pharmacokinetics and is effective, well tolerated and suitable for use in most patients with C. albicans infections, including children, the elderly and those with impaired immunity. Prophylactic administration of fluconazole can help to prevent fungal infections in patients receiving cytotoxic cancer therapy. The increasing use of fluconazole for the long-term prophylaxis and treatment of recurrent oral candidosis in AIDS patients has led to the emergence of C. albicans infections that are not responsive to conventional doses. Second-line therapy with a wider spectrum antifungal, such as itraconazole, should be sought if treatment with fluconazole fails. A solution formulation of itraconazole has recently been introduced to overcome the poor and variable absorption of its original capsule formulation. Efficacy and tolerability studies in HIV-positive or immunocompromised patients with C. albicans infections have shown that, although itraconazole solution is as effective as fluconazole, it is less well tolerated as first-line therapy. Itraconazole solution can be effective in AIDS patients with C. albicans infections that are non-responsive to fluconazole. No efficacy or tolerability data are available on the use of itraconazole solution in children or the elderly.

Pathogenicities and GP43kDa gene of three Paracoccidioides brasiliensis isolates originated from a nine-banded armadillo (Dasypus novemcinctus)

We studied three different isolates of Paracoccidioides brasiliensis obtained from the mesenteric lymph node (D3LY1), the spleen (D3S1) and the liver (D3LIV1) of the same armadillo (Dasypus novemcinctus). Pulmonal inflammatory area was evaluated by intravenous inoculation of 10(6) yeast cells of each isolates in young, male, ddY mice. Moreover, the partial sequence of GP43kDa gene of P. brasiliensis was analyzed. The lung inflammatory area was greater in animals inoculated with isolate D3S1. The partial sequence of GP43kDa gene indicated that isolate D3S1 is different from isolates D3LY1 and D3LIV1. This study suggested that the same armadillo might be susceptible to multiple P. brasiliensis isolates simultaneously.

Comparison between human and armadillo Paracoccidioides brasiliensis isolates by random amplified polymorphic DNA analysis

Sixty-three Paracoccidioides brasiliensis isolates obtained from three nine-banded armadillos (Dasypus novemcinctus), one Amazonian armadillo's and 19 clinical isolates were compared by random amplified polymorphic DNA analysis with the primer OPG-19. The isolates were divided into three major clusters, I, II and III. Coincidences between human and armadillo isolates were observed in clusters I and II. Cluster III consisted only of armadillos' isolates. The results suggested that (I) humans may acquire P. brasiliensis infection by contact with armadillo's environment, (II) there may be P. brasiliensis genotypes peculiar to the animal, and (III) individual armadillos may be infected with P. brasiliensis cells with different genotypes.

Molecular epidemiology and antifungal susceptibility of Cryptococcus neoformans isolates from Ugandan AIDS patients

Little is known of the antifungal susceptibility patterns and molecular epidemiology of Cryptococcus neoformans from tropical regions. We studied 164 clinical isolates of C. neofomans from 120 Ugandan AIDS patients with cryptococcal meningitis by analyzing their electrophoretic karyotypes and antifungal susceptibility profiles. Computer-assisted analysis of karyotype patterns was performed to generate dendrograms. MICs of fluconazole and flucytosine were determined by reference methods. A total of 43 distinguishable DNA types were identified among the 164 isolates. Only 30 patients (25%) were infected with their own unique strain of c. neoformans, whereas 75% of the patients shared their infecting strain with at least one other patient. Among 17 patients with more than one CSF isolate of C. neoformans, sequential isolates were identical or highly related in 12 (71%) and were different in five patients (29%). The isolates were susceptible to both fluconazole and flucytosine and there were no instances in which a stepwise increase in either fluconazole or flucytosine MICs was observed among serial isolates. These findings suggest that the epidemiology of cryptococcal disease in AIDS patients from tropical regions may be somewhat different from that observed in more temperate climates.

Molecular methods for epidemiological and diagnostic studies of fungal infections

Over the past two decades there has been a remarkable increase in the incidence of invasive fungal infections. Molecular methods, such as karyotyping, restriction analysis and polymerase chain reaction (PCR), have now been applied to improve our current understanding of the epidemiology of these fungal infections. For example, investigations on nosocomial outbreaks of fungal infections have been greatly facilitated by molecular methods. In addition, the ability to diagnose and identify deep-seated mycoses may be enhanced by the use of molecular techniques. In the near future it is possible that PCR-based methods will supplement, or perhaps even replace, traditional methods for detection of Candida albicans blood stream infections, invasive aspergillosis and Pneumocystis carinii pneumonia. This review examines the progress of molecular biology into the clinical arena of fungal epidemiology, laboratory identification and diagnosis.

Change in fluconazole susceptibility patterns and genetic relationship among oral Candida albicans isolates

OBJECTIVE

To assess the genetic homogeneity or heterogeneity within each set of Candida albicans isolates colonizing/infecting the oral cavities of HIV-infected patients undergoing azole therapy when changes in susceptibility to fluconazole were detected.

DESIGN

Fourteen HIV-positive patients suffering recurrent episodes of oral candidosis were prospectively followed from the first episode to the isolation of strains with decreased susceptibility to fluconazole. The strains of C. albicans isolated either from episodes or controls throughout the prospective study were analysed.

METHODS

Electrophoretic karyotyping and hybridization with the repeated sequence probe 27A were used to delineate sequential isolates. In vitro susceptibility tests to fluconazole and ketoconazole were also performed. The results obtained by DNA fingerprinting with the probe combined with computer-assisted analysis were used to assess the genetic relationships amongst the strains. In addition, comparison with the genetic relatedness of a group of geographically unrelated strains was made.

RESULTS

Isogenic populations of sequential isolates were observed only in two patients; 12 patients harboured heterogenic populations over time, although in 11 patients there was a predominant strain that was isolated more than once, and only one of these patients carried strains with a similarity index less than 80%. With the exception of two patients, each patient carried a major strain that became less susceptible to fluconazole. The similarity index for the unrelated strains was 59%.

CONCLUSIONS

HIV-infected patients may carry a mixed population of strains, but the strains tend to be related to each other. The strains were maintained throughout the course of infection and at least one developed secondary resistance to fluconazole.