CYP51A polymorphisms of Aspergillus fumigatus in lung transplant recipients: Prevalence, correlation with phenotype, and impact on outcomes

Azole resistance in Aspergillus fumigatus is increasing worldwide and can affect prognosis. It is mostly mediated by cytochrome P51 (CYP51) mutations. In lung transplant recipients (LTR), little is known regarding the prevalence and clinical impact of CYP51 mutations. One hundred thirty-one consecutive A. fumigatus isolates from 103 patients were subjected to CYP51A genotyping through PCR and sequencing. Antifungal susceptibility testing was performed using the Sensititre YeastOne YO-9© broth microdilution technique. Correlations between genotype, phenotype, clinical manifestations of Aspergillus infection, and clinical outcomes were made. Thirty-four (26%) isolates harbored mutations of CYP51A; N248K (n = 14) and A9T (n = 12) were the most frequent. Three isolates displayed multiple point mutations. No significant influences of mutational status were identified regarding azole MICs, the clinical presentation of Aspergillus disease, 1-year all-cause mortality, and clinical outcomes of invasive forms. In the specific context of lung transplant recipients, non-hotspot CYP51A-mutated isolates are regularly encountered; this does not result in major clinical consequences or therapeutic challenges.

LAY SUMMARY

In 131 isolates of Aspergillus fumigatus isolates originating from 103 lung transplant recipients, the CYP51A polymorphism rate was 26%, mostly represented by N248K and A9T mutations. These mutations, however, did not significantly impact azoles minimal inhibitory concentrations or clinical outcomes.

Synergic effect of simvastatin in combination with amphotericin B against environmental strains of Cryptococcus neoformans from northeastern Brazil: a prospective experimental study

BACKGROUND

Statins are used as cholesterol-lowering drugs and may also have direct antimicrobial effects.

OBJECTIVE

To evaluate synergic interactions between simvastatin and both amphotericin B and fluconazole, against environmental strains of Cryptococcus neoformans isolated from captive birds' droppings.

DESIGNAND SETTING

Experimental study conducted at Federal University of Piauí, Parnaíba, in collaboration with Federal University of Triângulo Mineiro, Uberaba, Brazil.

METHODS

Statin susceptibility tests of Cryptococcus neoformans samples were performed as prescribed in standards. Interactions of simvastatin with amphotericin and fluconazole were evaluated using the checkerboard microdilution method. Presence of these interactions was quantitatively detected through determining the fractional inhibitory concentration index (FICI).

RESULTS

Isolates of Cryptococcus neoformans were obtained from 30 of the 206 samples of dry bird excreta (14.5%) that were collected from pet shops and houses. Ten isolates were selected for susceptibility tests. All of them were susceptible to amphotericin and fluconazole. All presented minimum inhibitory concentration (MIC) > 128 µg/ml and, thus, were resistant in vitro to simvastatin. An in vitro synergic effect was shown through combined testing of amphotericin B and simvastatin, such that six isolates (60%) presented FICI < 0.500. Two isolates showed considerable reductions in MIC, from 1 µg/ml to 0.250 µg/ml. No synergic effect was observed through combining fluconazole and simvastatin.

CONCLUSION

These results demonstrate that simvastatin should be considered to be a therapeutic alternative, capable of potentiating the action of amphotericin B. However, further studies are necessary to clarify the real effect of simvastatin as an antifungal agent.

[In vitro susceptibility of Cuban Aspergillus spp. strains of clinical and environmental origin]

INTRODUCTION

The behavior of antifungal susceptibility of Aspergillus spp. in Cuba remains unknown. The antifungals recommended to treat aspergillosis are amphotericin B, itraconazole, voriconazole and echinocandins. The influence of the environment may set off the emergence of drug-resistance in these microorganisms.

OBJECTIVE

To evaluate in vitro susceptibility of Aspergillus spp. strains to amphotericin B, itraconazole and voriconazol, and the relationship between susceptibility patterns and their origin.

MATERIALS AND METHODS

Minimum inhibitory concentrations of amphotericin B, itraconazole and voriconazole were determined for 60 Aspergillus spp. strains of clinical and environmental origin using the M38-A2 method of the Clinical and Laboratory Standards Institute.

RESULTS

We found 21 amphotericin B resistant strains (mainly from clinical samples and hospital environments), as well as three itraconazole resistant strains (from non-hospital outdoor and indoor environments). No voriconazole resistance was found. No relationship was found between strain origin and susceptibility.

CONCLUSIONS

Results suggest the possible existence of environmental factors or interactions with resistant genotypes which may give rise to resistant phenotypes in our country. This is the first report of in vitro  Aspergillus spp. resistant strains in Cuba. These studies should be broadened and include molecular and phylogenetic analyses.