Efficacy of caspofungin in invasive candidiasis and candidemia – de-escalation strategy

Aflatoxin M1 in raw and imported powdered milk sold in Khartoum state, Sudan

The aim of this study is to determine the level of contamination of aflatoxin M1 (AFM1) in raw and imported powdered milk in Khartoum state, Sudan. Thirty-five samples of fresh cow milk were collected from different farms, based on the source of concentrated feed introduced to the dairy cows (locally vs. commercially produced) and the size of the farm (≤ 50 vs. >50 cows/farm). Also 12 samples of powdered milk were obtained from repacking companies in Khartoum state. The samples were analysed by a fluorometer, using the Vicam method. AFM1 was detected in all raw and powdered milk samples. Almost 50% of the contaminated powdered milk samples and all the raw milk samples exceeded the European Union limit of 0.05 µg/kg whereas 33% of the contaminated powdered milk samples and 77% of the raw milk samples exceeded the limit of Codex regulations (0.5 µg/kg). The results revealed that the concentration of AFM1 is affected significantly (P < 0.05) by the source of concentrated feed (locally produced or purchased) but not by the farm size. It was concluded that the levels of AFM1 in the milk samples indicated that the feeds offered to the cows were contaminated with aflatoxin B1 to such a level that it might cause a serious health problem to the public. Therefore, there is a need to limit the exposure to aflatoxin by imposing regulatory limits, as well as further studies on large scale bases are needed to investigate the amount of AFM1 in milk and dairy products.

Genotypic, phenotypic, and proteomic characterization of Candida glabrata during sequential fluconazole exposure

AIM

Candida glabrata is a major pathogen in humans known to be intrinsically resistant to fluconazole. However, genotypic, phenotypic, and proteomic changes associated with reduced susceptibility to fluconazole are not properly understood. The aim of this study was to observe specific phenotypic, chromosomal, and proteomic alterations in a Candida glabrata strain sequentially exposed to fluconazole.

METHODS

Candida glabrata was exposed to increased concentrations of fluconazole in RPMI for 55 days. Phenotypic changes were evaluated using standard assays. Molecular/proteomic changes in C. glabrata were analyzed by contour-clamped homogeneous electric field electrophoresis, reverse transcription-polymerase chain reaction, and mass spectrometry.

RESULTS

  Candida glabrata demonstrated increased fluconazole resistance (>256 μg/mL), with extensive cross-resistance to ketoconazole (0.38-3.0 μg), itraconazole (8 to >32 μg), and voriconazole (0.125-1.5 μg). Morphologically dissimilar colonies on RPMI/fluconazole agar demonstrated variable chromosomal profiles compared with the control isolate. Stable chromosomal changes were associated with a significantly higher (P<0.05) mRNA level of the hemolysin gene compared with the control. Phenotypic switching on CuSO4 agar was associated with variable metallothionein mRNA transcription levels. The proteome analysis of a fluconazole-resistant offshoot demonstrated a total of 98 protein spots, 25 showing a twofold upregulation.

CONCLUSION

Fluconazole exposure initiates the chance evolution of a new colonizing population with specific virulence traits.

Treatment and prophylaxis of invasive candidiasis with anidulafungin, caspofungin and micafungin:review of the literature

Working by a distinct cell wall-specific mechanism of action, the echinocandin class of antifungals has substantially expanded the range of available treatments for invasive Candida infections. Anidulafungin, caspofungin and micafungin were investigated versus drugs from earlier antifungal classes in large clinical trials that demonstrated their excellent clinical and microbiological efficacy in the primary treatment of invasive candidiasis. Therefore, and supported by a number of favourable pharmacological characteristics, the echinocandins rapidly became established in guidelines and clinical practice as primary treatment options for moderately to severely ill patients with invasive candidiasis. This article reviews the relevant clinical evidence that forms the basis for the use of echinocandins in the management of invasive candidiasis, and discusses their current role in the context of recent guideline recommendations and treatment optimization strategies.

Efficacy of anidulafungin, caspofungin and fluconazole in the early phase of infection in a neutropenic murine invasive candidiasis model

In this study, we investigated the in vivo efficacy of anidulafungin during the early phase of disseminated candidiasis in a neutropenic murine model and compared the results with those obtained for fluconazole. Antifungal efficacy was evaluated by reduction of fungal burden in the tissues of infected animals at periodic intervals during the first day of treatment. The fungal burden in tissues of drug-treated mice was reduced compared with controls in a time-dependent manner. At 24h after drug treatment, a >2 log(10) reduction of fungal burden in the kidney was obtained in the anidulafungin- and caspofungin-treated mice compared with a ca. 1.2 log(10) reduction in fluconazole-treated mice (P<0.003). There was no significant difference in the splenic fungal burden at 24h. Thus, echinocandins have excellent antifungal activity in the early phase of disseminated Candida albicans infection and may contribute to an improved outcome in critically ill immunocompromised/neutropenic patients.

The post-antifungal effect (PAFE) of amphotericin B, nystatin, ketoconazole and 5-fluorocytosine and its impact on the colonization traits of Candida glabrata

The post-antifungal effect (PAFE) has been shown to affect Candida pathogenicity, but there is little information on either PAFE or its association with the colonization traits of Candida glabrata. The objective of this study was to determine, in vitro, the PAFE on 14 C. glabrata isolates following exposure to amphotericin B (AMB), nystatin (NYS), ketoconazole (KETO) and 5-fluorocytosine (5FC). In addition, we evaluated the impact of PAFE on yeast adherence to buccal epithelial cells (BEC), cell-surface-hydrophobicity (CSH) and biofilm growth (BG) on denture acrylic surfaces. PAFE was induced following a 1-h exposure of yeasts to (x1-x4MIC) of AMB, NYS, KETO and 5FC in RPMI medium and, measured using automated turbidometry. The BEC adhesion, CSH and BG assays were performed by the methods of Kimura & Pearsall, Sweet et al., and Jin et al., respectively. Significant differences in PAFE (P < 0.001) were observed after exposure to AMB and NYS, but not KETO and 5FC. Following exposure to AMB, NYS, KETO and 5FC, significant inter-strain differences (P < 0.001) were observed in percentage terms in adhesion (39.0%, 43.48%, 38.28%, 35.07%) and biofilm growth (42.86%, 39.86%, 42.81%, 36.38%), respectively. Short exposure of C. glabrata to sub-cidal concentrations of antifungals modulates yeast growth and also affects some of their colonization traits.

Variation in susceptibility of bloodstream isolates of Candida glabrata to fluconazole according to patient age and geographic location in the United States in 2001 to 2007

We examined the susceptibilities to fluconazole of 642 bloodstream infection (BSI) isolates of Candida glabrata and grouped the isolates by patient age and geographic location within the United States. Susceptibility of C. glabrata to fluconazole was lowest in the northeast region (46%) and was highest in the west (76%). The frequencies of isolation and of fluconazole resistance among C. glabrata BSI isolates were higher in the present study (years 2001 to 2007) than in a previous study conducted from 1992 to 2001. Whereas the frequency of C. glabrata increased with patient age, the rate of fluconazole resistance declined. The oldest age group (> or = 80 years) had the highest proportion of BSI isolates that were C. glabrata (32%) and the lowest rate of fluconazole resistance (5%).

Effect of neem leaf extract and neem oil on Penicillium growth, sporulation, morphology and ochratoxin A production

In vitro trials were conducted to evaluate the effect of Azadirachtaindica (neem) extracts on mycelial growth, sporulation, morphology and ochratoxin A production by P. verrucosum and P. brevicompactum. The effect of neem oil extract from seeds and leaf was evaluated at 0.125; 0.25 and 0.5% and 6.25 and 12.5 mg/mL, respectively, in Yeast Extract Sucrose (YES) medium. Ochratoxin A production was evaluated by a thin-layer chromatography technique. Oil extracts exhibited significant (p ≤ 0.05) reduction of growth and sporulation of the fungi. No inhibition of ochratoxin A production was observed. Given its accessibility and low cost, neem oil could be implemented as part of a sustainable integrated pest management strategy for plant disease, as it has been shown to be fungitoxic by inhibition of growth and sporulation.

[Clinical use of micafungin for the treatment of invasive candidiasis in critical ill patients]

BACKGROUND

Over the last 30 years a significant increase of Candida spp. invasive disease has been observed in non-neutropenic critical ill patients. Both fluconazole and amphotericin B have been considered first line treatment for invasive (proven and probable) Candida spp. disease, although the mortality rate is still high.

OBJECTIVES

To review the current data on the use of micafungin for the treatment of Candida invasive disease in critical ill patients.

METHODS

The pharmacologic, mycological and clinical properties of micafungin are reviewed based on current published data. The use and efficacy of micafungin for the treatment of Candida invasive disease in critical ill patients is discussed.

RESULTS AND CONCLUSIONS

To reduce the rate of mortality more effective antifungals and pre-emptive treatment strategies are currently warranted. Candins achieve better results for the treatment of invasive Candida disease in non-neutropenic critical ill patients. Micafungin has a good safety profile (similar to fluconazole). Micafungin is a first line drug for the treatment of invasive Candida disease and may be used as a pre- emptive approach followed by a de-escalating strategy with azoles.