Evaluation of the disk diffusion method compared to the microdilution method in susceptibility testing of anidulafungin against filamentous fungi.

Susceptibility testing of anidulafungin (AFG) against 32 mold isolates showed an excellent correlation between disk diffusion (DD) and broth microdilution methods. Based on our data, a 2-microg disk of AFG and a 24-h reading time might represent the best parameters for AFG DD testing against filamentous fungi.

Posaconazole against Candida glabrata isolates with various susceptibilities to fluconazole.

We investigated the in vitro activities of posaconazole (POS), fluconazole (FLC), amphotericin B (AMB), and caspofungin (CAS) against four clinical isolates of Candida glabrata with various susceptibilities to FLC (FLC MICs ranging from 1.0 to >64 microg/ml). POS MICs ranged from < or =0.03 to 0.5 microg/ml; AMB MICs ranged from 0.25 to 2.0 microg/ml, while CAS MICs ranged from 0.03 to 0.25 microg/ml. When FLC MICs increased, so did POS MICs, although we did not observe any isolate with a POS MIC greater than 0.5 mug/ml. Time-kill experiments showed that POS, FLC, and CAS were fungistatic against all isolates, while AMB at eight times the MIC was fungicidal against three out of four isolates of C. glabrata tested. Then, we investigated the activity of POS in an experimental model of disseminated candidiasis using three different isolates of C. glabrata: one susceptible to FLC (S; FLC MICs ranging from 1.0 to 4.0 microg/ml; POS MIC of < or =0.03 microg/ml), one susceptible in a dose-dependent manner (SDD; FLC MICs ranging from 32 to 64 microg/ml; POS MICs ranging from 0.125 to 0.25 microg/ml), and another one resistant to FLC (R; FLC MIC of >64 microg/ml; POS MIC of 0.5 microg/ml). FLC significantly reduced the kidney burden of mice infected with the S strain (P = 0.0070) but not of those infected with the S-DD and R strains. POS was significantly effective against all three isolates at reducing the kidney fungal burden with respect to the controls (P ranging from 0.0003 to 0.029). In conclusion, our data suggest that POS may be a useful option in the management of systemic infections caused by C. glabrata. Additionally, the new triazole may be a therapeutic option in those cases where an FLC-resistant isolate is found to retain a relatively low POS MIC.

[Surveillance of the sanitary conditions of a public swimming pool in the city of Palermo (Italy)]. / Sorveglianza igienico-sanitaria di una piscina di uso pubblico della città di Palermo (Italia).

In a previous study we evaluated the microbiological quality of water of seven pools in the city of Palermo through evaluation of bacterial indicators of faecal contamination and of protozoa (Giardia and Cryptosporidium). In this study we also searched for the presence of fungi in two swimming pools of a public swimming facility in the same city. Samples were collected from both pools, their filtration systems and floor surfaces of the facility. Chemical-physical and microbiological examination of water of the two pools have shown that quality of water depends on the concentration of residual free chlorine and on the number of bathers in the pool. The values of four microbiological parameters (bacterial load at 22 degrees C and 36 degrees C, presence of coagulase-negative Staphylococci and Pseudomonas spp.) increased with diminishing chlorine concentrations and with increasing number of pool users. Faecal bacteria, Giardia and Cryptosporidium were not found. On the other hand, various fungi were isolated from floor surfaces and pool water even in the presence of optimal chlorine concentrations. This study confirms the importance of regular maintenance of pool disinfection systems and suggests the need to search for other micro-organisms not included in the current legislation (Giardia, Cryptosporidium and fungi).

Posaconazole activity against Candida glabrata after exposure to caspofungin or amphotericin B.

We evaluated the effects of sequential therapy with caspofungin (CAS) or amphotericin B (AMB) followed by posaconazole (POS) against Candida glabrata. The susceptibilities to POS of yeast cells pre-exposed to CAS or AMB were identical to those of untreated cells as shown by standard Clinical and Laboratory Standards Institute broth dilution, cell viability, and disk diffusion methods. We then investigated the activity of sequential regimens in an experimental model of disseminated candidiasis. CAS given at 1 mg/kg/day for 2 days followed by POS at either 15 or 30 mg/kg/day significantly reduced the counts compared to the controls, but this treatment was not superior to the use of CAS alone. Also, sequential regimens with AMB given at 1 mg/kg/day for 2 days followed by POS (AMB/POS) were effective at reducing the fungal burden against the controls. In addition, AMB/POS with both doses of the triazole were significantly more effective than AMB alone. Overall, our data showed that there is no therapeutic advantage in using CAS followed by POS, whereas an induction therapy with AMB followed by a maintenance regimen with POS might be a suitable strategy in managing C. glabrata infections.

Comparison between disk diffusion and microdilution methods for determining susceptibility of clinical fungal isolates to caspofungin.

We compared the caspofungin (CAS) susceptibility testing results generated by the disk diffusion (DD) assay with the results of the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BD) reference method for 106 yeast isolates. The isolates represented 11 different fungal species, including Candida albicans (n = 50), C. parapsilosis (n = 10), C. glabrata (n = 10), C. tropicalis (n = 10), C. guillermondii (n = 6), C. rugosa (n = 5), C. krusei (n = 5), C. kefyr (n = 2), C. pelliculosa (n = 2), Saccharomyces cerevisiae (n = 3), and Geotrichum candidum (n = 3). The DD assay was performed in supplemented Mueller-Hinton agar with CAS, which was tested at concentrations of 2, 10, and 25 mug per disk. MICs and inhibition zone diameters were evaluated at 24 and 48 h. In general, the results obtained by the DD assay correlated well with those obtained by the BD method. In particular, a significant correlation between methods was observed when CAS was used at concentration of 2 mug/disk at a reading time of either 24 or 48 h.