Molecular detection of virulence factors and antibiotic resistance pattern in clinical Enterococcus faecalis strains in Sardinia.

In this study, the antibiotic resistance pattern and the presence of genes encoding several virulence factors in 91 Enterococcus faecalis strains isolated from different human clinical sources in Sardinia were investigated. Genotypic determination of virulence genes (gelE, esp, agg, ace, cylA,B,M,L(L),L(S), efaA, fsrB) was carried out by PCR. The production of gelatinase and haemolytic activity were also determined. Antimicrobial susceptibility tests were performed by an automated microdilution test (Vitek). The strains examined in this study contained at least one and up to as many as all virulence genes investigated. Examining the distribution of these factors in the different groups of clinical strains, we found that all but one virulence determinant were detected more frequently among urinary isolates. The detection of some factors by PCR did not always correlate with its phenotypic expression. Antibiotic susceptibilities among the Enterococcus faecalis strains investigated in our study were typical for the species, with expected levels of acquired resistance. Faecal isolates had the highest percentage of resistance, especially to high level-gentamicin, ciprofloxacin and norfloxacin. In summary, a wide variety of genes encoding virulence factors have been detected among our clinical Enterococcus faecalis strains, and those isolated from UTI were characterized by a higher virulence potency compared with strains from other clinical sources. Silent virulence genes (cyl or gelE) were frequently detected, therefore both the genotypic and phenotypic assays seem necessary for a better characterization of the strains. Our results may serve as a basis for additional surveillance studies of infections caused by this microorganism.

[Phenotypic and molecular characterization of Candida species in ICU]. / Caratterizzazione fenotipica e molecolare di Candida isolate in un reparto di Terapia Intensiva.

Two hundred sixty three Candida isolates were obtained from specimens of patients hospitalized in a Intensive Care Unit. Candida albicans was the predominant species, followed by C. tropicalis, C. krusei, C. glabrata e C. parapsilosis. For C. albicans isolates, amphotericin B was the more efficient antifungal (2.3% of resistant strains), while voriconazole was the more efficient for C. krusei and C. glabrata, known for their lower susceptibility to fluconazole. RAPD-PCR technique with CDU primer was used for the molecular characterization of 48 C. albicans strains isolated from 10 patients. Genetic similarity at 90% level was observed for some Candida strains isolated from the same patient, indicating a possible colonization from the original strain. Moreover the high similarity coefficient observed between isolates from different patients may indicate an exogenous colonization originating from hospital-endemic strains or inadequate manipulation by health care workers.

Prevalence of Candida species in different hospital wards and their susceptibility to antifungal agents: results of a three year survey.

Over a three years period, 472 Candida isolates were obtained from specimens of patients hospitalized either in "at risk", Bone Marrow Transplant Unit and Intensive Care Unit, or in conventional wards, Pneumological Divisions of the "Binaghi" Hospital of Cagliari (Italy). Antifungal susceptibility profile to amphotericin B, voriconazole, fluconazole and ketoconazole was determined. Candida albicans was the predominant species while Candida krusei was the most frequent non-albicans species. C. krusei was significantly more common among Bone Marrow Transplant Unit and Intensive Care Unit than Pneumological Divisions patients (17.9% and 14.1% vs. 6.0%; p < 0.05). No significant differences were observed when the same distribution was analysed with regard to the other Candida species or when Bone Marrow Transplant Unit and Intensive Care Unit were compared. The profiles of susceptibility to the antifungal drugs among isolates from the different hospital wards showed no significant differences, even though most of MIC values were higher for Intensive Care Unit isolates compared to those for Bone Marrow Transplant Unit and Pneumological Divisions. For C. albicans isolates, amphotericin B was the more efficient antifungal (97.7% S), while fluconazole (6.1% R [Resistant] and 2.6% SDD [Susceptible Dose Dependent]) and ketoconazole (4.1% R and 3.2% SDD) showed the lowest activity. Voriconazole was the more efficient antimycotic for C. krusei (96.7% S) and Candida glabrata (100% S [Sensible]) isolates. This study has shown a significantly higher presence of non-albicans Candida in at risk wards as well as a decreased susceptibility to the older azoles (ketoconazole and fluconazole) among C. albicans isolates.