First case of proven invasive pulmonary infection due to Trichoderma longibrachiatum in a neutropenic patient with acute leukemia

Trichoderma species are saprophytic filamentous fungi that can be found all over the word. These fungi show increasing medical importance as opportunistic human pathogens, particularly in immunocompromised patients. Invasive infections due to Trichoderma are rare and definitive diagnosis is complex to achieve because of the lack of specific diagnosis tools. We report in this work the first proven case of invasive pulmonary infection due to T. longibrachiatum in a 69-year-old white male with hematologic malignancy. The patient was successfully treated initially with voriconazole alone followed by a combination of voriconazole and caspofungine.

Ruling out nosocomial transmission of Cryptosporidium in a renal transplantation unit: case report

Background

Cryptosporidium spp. is a ubiquitous parasite affecting humans as well as domestic and wild vertebrates, causing diarrhea in both immunocompetent and immunocompromised hosts worldwide. Its transmission occurs primarily by the fecal-oral route. In humans, C. parvum and C. hominis are the most prevalent species, whereas immunocompetent and immunocompromised individuals can also be infected by other zoonotic species. Renal transplant patients are prone to develop cryptosporidiosis, which can induce severe and life-threatening diarrhea.

Case presentation

We report here a series of nearly concomitant cases of acute symptomatic cryptosporidiosis in three renal transplant patients attending the Strasbourg University Hospital Nephrology Unit. The clinical presentation was persistent diarrhea and acute renal failure. The diagnosis was confirmed by microscopic stool examination using a modified Ziehl-Neelsen staining method and species identification by molecular tools. All patients were treated with nitazoxanide and recovered from diarrhea after 14 days of therapy.

Conclusion

Genotypic species identification was not consistent with an epidemic context, thus underlining the need for genotyping to monitor at risk patients.

Dynamics of fungal colonization in a new medical mycology laboratory

OBJECTIVE OF THE STUDY

Study of the spatio-temporal fungal colonization in a new medical mycology laboratory.

METHODS

A 17-month survey of airborne fungal contamination was conducted in a new medical mycology laboratory at a tertiary care university hospital. This survey was implemented at three different periods: before the new premises were occupied (period A), during the move into the new laboratory (period B) and after resumption of the mycological activities in these new premises (period C).

RESULTS

During period A, the airborne fungal load ranged from 2.3 to 6 cfu/m(3). The most frequently recovered airborne fungi were Penicillium spp. (75 to 100%). During period B, a dramatic increase in Penicillium chrysogenum conidia was observed in the air of the new laboratory (40 to 160 cfu/m(3)). During period C, the fungal load ranged from 4.5 to 8.4 cfu/m(3). Penicillium was the most common genus identified in rooms of the laboratory where no filamentous fungi were handled, while Aspergillus was clearly the predominant genus (78%) in the room dedicated to the culture of filamentous fungi.

CONCLUSIONS

We suggest that the specific fungal ecology in air of the room dedicated to the culture of filamentous fungi is due to the handling of a large number of medical strains of A. fumigatus.

Reduced fungal contamination of the indoor environment with the Plasmair™ system (Airinspace)

Aspergillus spp. and other moulds cause life-threatening opportunistic infections in immunocompromised patients. Indoor contamination and construction work that liberate fungal spores are a major source of nosocomial aspergillosis. Dijon hospital is a tertiary care institution in northeast France undergoing construction work beside high-risk clinical units. To determine the impact of this activity, a surveillance programme was implemented one year before building work began in order to establish baseline levels of contamination. Air and surface fungal contamination in adult and paediatric haematology units were prospectively examined following use, or not, of a new air-treatment system with mobile Plasmair units (Airinspace). There were significant reductions in overall fungal contamination for the Plasmair treated rooms for air and surface samples in both clinical units. Plasmair treatment also significantly reduced A. fumigatus in the air. These data suggest that Plasmair units may provide an efficient method of reducing indoor fungal contamination in hospitals.

Bioactive steroidal saponins from Smilax medica

Two new spirostanol saponins ( 1 and 2) were isolated from the roots of Smilax medica, together with the known smilagenin 3-O-beta-D-glucopyranoside (3). Their structures were determined by spectroscopic methods including 1D- and 2D-NMR experiments. Compounds 1 and 2 exhibited antifungal activity against the human pathogenic yeasts Candida albicans, C. glabrata and C. tropicalis (MICs between 6.25 and 50 microg/mL) whereas 3 was inactive.

Antifungal steroid saponins from Dioscorea cayenensis

From the rhizomes of Dioscorea cayenensis Lam.-Holl (Dioscoreaceae), the new 26- O- beta- D-glucopyranosyl-22-methoxy-3 beta,26-dihydroxy-25( R)-furost-5-en-3- O- alpha- L-rhamnopyranosyl-(1-->4)- alpha- L-rhamnopyranosyl-(1-->4)-[ alpha- L-rhamnopyranosyl-(1-->2)]- beta- D-glucopyranoside ( 1) was isolated together with the known dioscin ( 2) and diosgenin 3- O- alpha- L-rhamnopyranosyl-(1-->4)- alpha- L-rhamnopyranosyl-(1-->4)-[ alpha- L-rhamnopyranosyl-(1-->2)]- beta- D-glucopyranoside ( 3). Their structures were established on the basis of spectral data. Compound 2 exhibited antifungal activity against the human pathogenic yeasts Candida albicans, C. glabrata and C. tropicalis (MICs of 12.5, 12.5 and 25 micro g/mL, respectively) whereas 3 showed weak activity and 1 was inactive.

The effects of temperature, water activity and pH on the growth of Aeromonas hydrophila and on its subsequent survival in microcosm water

AIMS

The influence of temperature, water activity and pH on the growth of Aeromonas hydrophila, and on its survival after transfer in nutrient-poor water were assessed.

METHODS AND RESULTS

Experiments were carried out according to a Box-Behnken matrix at 10-30 degrees C, 0.95-0.99 water activity (aw) and pH 5-9. The effect of each factor on the kinetic parameters of growth (i.e. the maximal specific growth rate, mumax, and the lag time, lambda) and on the decline of the bacteria in microcosm water (time to obtain a reduction of 5 log, T5 log) were studied by applying central composite design.

CONCLUSIONS

The major effect of temperature and water activity on the growth of A. hydrophila was highlighted, whereas the effect of pH in these experimental conditions was not significant. Models describing the effect of environmental parameters on the growth of A. hydrophila were proposed. The effect of the growth environment, and particularly the incubation temperature, have an influence on the survival ability of the bacteria in nutrient-poor water.

SIGNIFICANCE AND IMPACT OF THE STUDY

The Box-Behnken design was well suited to determine the influence of environmental factors on the growth of A. hydrophila and to investigate the effect of previous growth conditions on its survival in microcosm water.

Influence of inoculum preparation on the growth of Penicillium chrysogenum

AIMS

The influence of the spore preparation on subsequent fungal growth of Penicillium chrysogenum was assessed.

METHODS AND RESULTS

The influence of four factors [the nature of the diluting solution (physiological water and physiological water added with Tween-80), the age of the sporulating culture (4, 8 and 12 days), the strain (737, 738 and 740) and the inoculum size (102, 103, 104 and 105 spores ml(-1)] on two responses (i.e. the radial growth rate, mu, and the lag time, lambda) was studied using an experimental screening methodology.

CONCLUSIONS

The main conclusion was the strong effect of the inoculum size on lambda. In contrast, the diluting solution had no effect on both the experimental responses. In order to obtain the highest growth rates, it is recommended to use 4-day-old sporulating cultures with an inoculum size of 102 spores ml(-1).

SIGNIFICANCE AND IMPACT OF THE STUDY

There is a need for standardizing spore preparation in predictive mycology. The screening methodology is a powerful tool to determine the influence of qualitative and quantitative factors on various biological responses and can be applied widely in microbiology.

Relationship between spore germination kinetics and lag time during growth of Mucor racemosus

AIMS

Spore germination requires microscopic observation whereas fungal growth results in a macroscopic examination. This paper aims at establishing a relationship between the percentage of germinated spores and parameters easily available from visible development.

METHODS AND RESULTS

About 225 spores of Mucor racemosus were inoculated on PDA medium and incubated at 15 degrees and 25 degrees C. Germination kinetics were modelled by a logistic function. Fungal development provided two parameters, a growth rate, micro, and a lag period, lambda, defined as the slope of the straight line of the graph radius (mm) vs time (h) and the intercept of this line with the X-axis, respectively.

CONCLUSIONS

It was found that the lag period coincided with the completion of the germination process, although the number of spores inoculated should be controlled carefully.

SIGNIFICANCE AND IMPACT OF THE STUDY

Providing that this result can be generalized, this procedure would constitute a significant breakthrough for predicting food spoilage by moulds.

Comparison of the effects of temperature and water activity on growth rate of food spoilage moulds

The influence of temperature (T) and water activity (aw) on the growth rate (mu) of seven moulds (Alternaria alternata, Aspergillus flavus, Cladosporium cladosporioides, Mucor racemosus, Penicillium chrysogenum, Rhizopus oryzae and Trichoderma harzianum) was assessed in suboptimal conditions. Firstly, the dependence of fungal growth on temperature, at aw 0.99, was modelled through an approach described previously for bacteria. A dimensionless growth rate variable: mu(dimalpha)=mu/mu (optalpha) depended on the following normalised temperature: T(dim)=(T-T(min))/(T(opt)- T(min)) according to a power function: mu(dimalpha)=[T(dim)]alpha, where alpha was an exponent to be estimated. Secondly, the same approach was used to describe the influence of aw on fungal growth, at the respective optimum temperatures for each mould. Similarly, mu(dimbeta)=mu/mu(optbeta) depended on the following normalised water activity: a(wdim)=(aw-a(wmin))/(a(wopt)-a(wmin)) according to a power function: mu(dimbeta)=[a(wdim)](beta). Results show: (i) for each mould, the alpha-value is significantly less than the beta-value, confirming that water activity has a greater influence than temperature on fungal development; (ii) the alpha-values and the beta-values depend on the mould; (iii) the alpha-value is less than 1 for the mesophilic mould A. flavus, whereas the other moulds are characterised by higher alpha-values ranging from 1.10 to 1.54; (iv) the mesophilic A. flavus exhibits a low beta-value, 1.50, compared to the hydrophilic T. harzianum, beta=2.44, while beta-values are within the range (1.71-2.37) for the other moulds.

Application of Doehlert design to determine the combined effects of temperature, water activity and pH on conidial germination of Penicillium chrysogenum

AIMS

The influence of temperature, water activity and pH on the time necessary for germination of 90% of Penicillium chrysogenum conidia inoculated (T90) was determined.

METHODS AND RESULTS

A new experimental device was developed for easy monitoring of the germination process. Experiments were carried out according to a Doehlert matrix at 11-31 degrees C, 0.86-0.98 water activity (a(w)) and pH 3.5-6.5. In these conditions, a second order polynomial relationship between T90 and the environmental factors was established for the different humectants used throughout this study (e.g. glycerol and sorbitol) with regression coefficients close to 0.97.

CONCLUSIONS

For both humectants, the major effect of temperature and water activity on T90 was highlighted, whereas the effect of pH on T90 in these experimental conditions was not significant. The combined effect of temperature and water activity on T90 was also demonstrated.

SIGNIFICANCE AND IMPACT OF THE STUDY

Both the experimental set-up and the Doehlert matrix were well suited to determine the influence of environmental factors on mould germination.

A temperature-type model for describing the relationship between fungal growth and water activity

Growth of Penicillium chrysogenum, Aspergillus flavus, Cladosporium cladosporioides and Alternaria alternata at their respective optimum temperatures was studied in Potato Dextrose Agar (PDA) medium at different water activities (a(w)) adjusted with glycerol. The growth rate (mu) was expressed as the increase in colony radius per unit of time. This paper extends the model that showed the relationship between temperature and bacterial growth rate developed by Rosso et al. [J. Theor. Biol. 162 (1993) 447] to describe the influence of a(w) on fungal development. An excellent correlation between the experimental data and the model predictions was obtained, the regression coefficients (r2) were greater than 0.990, with the exception of that for A. flavus (r2 = 0.982). In addition, the use of such a model allows predictions of the cardinal water activities: a(wmin), a(wopt) and a(wmax). The estimation of the minimum water activity (a(wmin)) was in accordance with data literature for all the moulds considered here, but seemed to be slightly underestimated for P. chrysogenum and A. flavus when compared to our experimental values. The estimations of the optimal water activity (a(wopt)) and the optimal growth rate (muopt) were in excellent agreement to the experimental results for the four moulds. Through this example, it is suggested that the same approach for modelling can be used for various microorganisms (e.g. bacteria and moulds), and different environmental parameters (e.g. temperature and water activity).

Prediction of conidial germination of Penicillium chrysogenum as influenced by temperature, water activity and pH

AIMS

Conidial germination of Penicillium chrysogenum was carried out under operating conditions compatible with a pastries manufacturing process.

METHODS AND RESULTS

A range, limited by two experimental values, was defined for each environmental factor tested: temperature (15 or 25 degrees C), water activity (0.75 or 0.85) and pH (3.5 or 5.5). A closed device was made, which maintained an equilibrium between water activity of the culture medium and atmospheric relative humidity during 25 days, to follow spore germination. The combined effects of temperature, water activity and pH on spore germination were studied by applying factorial design methodology.

CONCLUSIONS

Higher rates of spore germination were associated with a high level of water activity. The incubation temperature also had a positive effect. A significant positive interaction between water activity and temperature was observed. Under these specific experimental conditions, pH did not have a significant effect on conidial germination.

SIGNIFICANCE AND IMPACT OF THE STUDY

A model describing the behaviour of fungal conidia is proposed.