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Forty-six isolates of Candida parapsilosis, each from a single patient, were collected from July 1993 through March 1999 at the University of Ancona Hospitals and Clinics. Twenty-eight strains were isolated from superficial lesioned sites, including skin, nails and other sources while 18 strains were isolated from blood. The isolates were typed by electrophoretickaryotyping (EK) and tested for their susceptibility to fluconazole (FLC),itraconazole (ITC), flucytosine (5-FC), and amphotericin B (AMB). Ourdata confirmed that EK is a useful technique for DNA typing of isolates ofCandida parapsilosis and showed that the source of isolation is notassociated with a given DNA type. Although strains belonging to this speciesof Candida are susceptible to the most common antifungals, including the triazoles, the degree of ITC susceptibility was dose dependent (MIC rangingfrom 0.25–0.5 μg/ml) for 98% of the isolates.

A series of 35 strains of Candida glabrata isolated from 29 subjects (5 AIDS patients and 24 HIV-seronegative individuals) were typed by electrophoretic karyotyping and tested for their susceptibilities to both fluconazole and itraconazole. Almost every individual harboured his/her own specific isolate (DNA type). Neither the source of isolation nor the patient's HIV status was associated with a given DNA type. Recurrences were generally due to the persistence of the same DNA type over time. Only 9% of the isolates showed reduced susceptibility to fluconazole (MICor = 8.0 microg/ml), while 43% of the isolates showed reduced susceptibility to itraconazole (MICor = 0.25 microg/ml) (P = 0.02). These data show that electrophoretic karyotyping is a useful technique for DNA typing of isolates of Candida glabrata. Care must be taken prior to initiation of antifungal therapy with either of these drugs.

Over a 16 month period we conducted a prospective study in a cohort of 45 HIV-positive patients to detect the development of resistance to fluconazole and to analyse the epidemiology of oropharyngeal candidosis (OPC). Each episode was treated with fluconazole 100 mg/day po for 10 days. All yeast isolates were tested for their in-vitro susceptibility to fluconazole. Multiple strains of Candida albicans simultaneously isolated from a given patient were typed by electrophoretic karyotyping. Overall, 106 episodes of OPC were diagnosed among the 45 patients: 18/45 patients (40%) had only one episode, 11/45 (24%) had two episodes, and the remaining 16/45 (36%) had three or more episodes (range 3-7). Cure (complete resolution of signs and symptoms and negative post-treatment cultures) and improvement (complete resolution of signs and symptoms but positive post-treatment cultures) were observed in 30/106 (28%) and 69/106 (65%) episodes of OPC, respectively. Failure (absence of improvement or exacerbation of signs and symptoms) was observed in seven episodes (7%) from four patients. In two of these four patients a significant and progressive increase in fluconazole MICs was observed: from 0.25 to 16 mg/L in one patient, and from < or = 0.125 to 32 mg/L in the second one. Tests on multiple colonies from individual isolation plates showed that it was not unusual to obtain different fluconazole MICs, indicating that, in order to avoid misleading results, one should perform in-vitro susceptibility testing by using a multiple colony inoculum rather than an inoculum made from a single colony. A total of 213 strains of C. albicans isolated from seven patients who suffered from four or more episodes of OPC through the course of the study were typed by electrophoretic karyotyping. Five individuals (71%) were infected with yeasts with only one DNA type, while the other two patients showed the presence of two or three different DNA types. The simultaneous presence of multiple types was found only in one of the seven subjects. Our data confirm the efficacy of fluconazole 100 mg/day for the treatment of OPC in HIV patients. Isolation of fluconazole-resistant strains of C. albicans with this regimen is rare. The vast majority of HIV patients are infected with a unique strain of C. albicans throughout each episode of infection. A minority of patients, however, can harbour strains of C. albicans with variable patterns of fluconazole susceptibility simultaneously.

Random amplification of polymorphic DNA and inter-repeat polymerase chain reaction (IR-PCR) were compared with restriction fragment length polymorphism (RFLP) analysis as methods for DNA typing of Candida albicans. Forty-seven strains of Candida albicans isolated from the oral cavities of five AIDS patients undergoing fluconazole therapy were analyzed. There was an excellent correspondence between the DNA types obtained by both PCR-based techniques and by RFLP. With the exception of one patient who was infected with three DNA types of Candida albicans during a five-year observation period, the patients each harboured only one major strain, which became progressively less susceptible to fluconazole. Each DNA type was unique to a patient. The data suggest that these typing methods are suitable for investigating the epidemiology of oropharyngeal candidiasis in this patient group.

A checkerboard microdilution method was applied to study the in vitro interaction of terbinafine with either fluconazole and itraconazole against 30 strains of Candida albicans. Synergy was observed in 40% of the terbinafine-fluconazole interactions and in 43% of the terbinafine-itraconazole interactions, while antagonism was not observed. Even when only additivity was achieved, the combinations still showed beneficial effects since at least twofold reductions in the MICs of both drugs were found in 100% of the terbinafine-fluconazole interactions and in 76% of the terbinafine-itraconazole interactions.

We report an outbreak of infection due to genotypically identical Candida parapsilosis isolates among patients hospitalized in a pediatric oncology unit. Control cultures showed genetic relatedness between strains isolated from the patients and those isolated from the hands of a health care worker. Our data underline the importance of an effective surveillance program for preventing nosocomial fungal infections.

Subgingival colonization by Candida albicans has been described in human immunodeficiency virus (HIV)-infected individuals, but subgingival isolates have scarcely been characterized, particularly with respect to genotype and antifungal susceptibility. A series of 29 subgingival strains of C. albicans isolated from nine HIV-infected individuals was typed by electrophoretic karyotyping and tested for susceptibility to fluconazole, itraconazole, the new investigational triazole posaconazole and amphotericin B. DNA typing showed genetic heterogeneity within subgingival isolates, as almost every individual harbored his/her own specific isolate. Genetic identity was usually demonstrated within oral and subgingival isolates simultaneously collected from the same individual, but a number of DNA types were found to be unique to subgingival strains. These findings suggest that colonization is not just the result of Candida spreading from oral surfaces, and that subgingivally adapted strains could be involved. All isolates were susceptible to all the triazole drugs tested and amphotericin B. Additional studies on subgingival Candida colonization and further characterization of subgingival isolates are now required to clarify the role of Candida as opportunistic periodontal pathogen.

Over a 16 month period we conducted a prospective study in a cohort of 45 HIV-positive patients to detect the development of resistance to fluconazole and to analyse the epidemiology of oropharyngeal candidosis (OPC). Each episode was treated with fluconazole 100 mg/day po for 10 days. All yeast isolates were tested for their in-vitro susceptibility to fluconazole. Multiple strains of Candida albicans simultaneously isolated from a given patient were typed by electrophoretic karyotyping. Overall, 106 episodes of OPC were diagnosed among the 45 patients: 18/45 patients (40%) had only one episode, 11/45 (24%) had two episodes, and the remaining 16/45 (36%) had three or more episodes (range 3-7). Cure (complete resolution of signs and symptoms and negative post-treatment cultures) and improvement (complete resolution of signs and symptoms but positive post-treatment cultures) were observed in 30/106 (28%) and 69/106 (65%) episodes of OPC, respectively. Failure (absence of improvement or exacerbation of signs and symptoms) was observed in seven episodes (7%) from four patients. In two of these four patients a significant and progressive increase in fluconazole MICs was observed: from 0.25 to 16 mg/L in one patient, and fromor = 0.125 to 32 mg/L in the second one. Tests on multiple colonies from individual isolation plates showed that it was not unusual to obtain different fluconazole MICs, indicating that, in order to avoid misleading results, one should perform in-vitro susceptibility testing by using a multiple colony inoculum rather than an inoculum made from a single colony. A total of 213 strains of C. albicans isolated from seven patients who suffered from four or more episodes of OPC through the course of the study were typed by electrophoretic karyotyping. Five individuals (71%) were infected with yeasts with only one DNA type, while the other two patients showed the presence of two or three different DNA types. The simultaneous presence of multiple types was found only in one of the seven subjects. Our data confirm the efficacy of fluconazole 100 mg/day for the treatment of OPC in HIV patients. Isolation of fluconazole-resistant strains of C. albicans with this regimen is rare. The vast majority of HIV patients are infected with a unique strain of C. albicans throughout each episode of infection. A minority of patients, however, can harbour strains of C. albicans with variable patterns of fluconazole susceptibility simultaneously.