Species-Specific Antifungal Susceptibility Patterns of Scedosporium and Pseudallescheria Species

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>Since the separation of<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Pseudallescheria boydii</jats:named-content>and<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">P. apiosperma</jats:named-content>in 2010, limited data on species-specific susceptibility patterns of these and other species of<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Pseudallescheria</jats:named-content>and its anamorph<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Scedosporium</jats:named-content>have been reported. This study presents the antifungal susceptibility patterns of members affiliated with both entities. Clinical and environmental isolates (<jats:italic>n</jats:italic>= 332) from a wide range of sources and origins were identified down to species level and tested according to CLSI M38-A2 against eight antifungal compounds. Whereas<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">P. apiosperma</jats:named-content>(geometric mean MIC/minimal effective concentration [MEC] values of 0.9, 2.4, 7.4, 16.2, 0.2, 0.8, 1.5, and 6.8 μg/ml for voriconazole, posaconazole, isavuconazole, itraconazole, micafungin, anidulafungin, caspofungin, and amphotericin B, respectively) and<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">P. boydii</jats:named-content>(geometric mean MIC/MEC values of 0.7, 1.3, 5.7, 13.8, 0.5, 1.4, 2.3, and 11.8 μg/ml for voriconazole, posaconazole, isavuconazole, itraconazole, micafungin, anidulafungin, caspofungin, and amphotericin B, respectively) had similar susceptibility patterns, those for<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">S. aurantiacum</jats:named-content>,<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">S. prolificans</jats:named-content>, and<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">S. dehoogii</jats:named-content>were different from each other. Voriconazole was the only drug with significant activity against<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">S. aurantiacum</jats:named-content>isolates. The MIC distributions of all drugs except voriconazole did not show a normal distribution and often showed two subpopulations, making a species-based prediction of antifungal susceptibility difficult. Therefore, antifungal susceptibility testing of all clinical isolates remains essential for targeted antifungal therapy. Voriconazole was the only compound with low MIC values (MIC<jats:sub>90</jats:sub>of ≤2 μg/ml) for<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">P. apiosperma</jats:named-content>and<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">P. boydii</jats:named-content>. Micafungin and posaconazole showed moderate activity against the majority of<jats:named-content xmlns:xlink="http://www.w3.org/1999/xlink" content-type="genus-species" xlink:type="simple">Scedosporium</jats:named-content>strains.</jats:p>

Isolation of Scedosporium apiospermum (Teleomorph: Pseudallescheria apiosperma) from an Acute Myeloid Leukemia Patient

“…Yaygın skedosporyozda etkin bir tedavi bulunmamaktadır. Scedosporium tür-lerinden S.prolificans, antifungal ilaçlara S.apiospermum'a oranla daha dirençli olmasıyla farklılık gösterir 13 . P.apiosperma, S.apiospermum ve S.prolificans ile oluşan enfeksiyonlarda, in vitro duyarlı olarak saptanan amfoterisin B ile tedavide yanıtsızlık bulunur.…”

“…Bizim olgumuzda da, izole edilen kökenin vorikonazol MİK değeri 0.06 µg/ml olarak bulunmuş ve enfeksiyon başarılı bir şekilde tedavi edilmiştir. Lackner ve arkadaşlarının 13 çalışmasında, kaspofungin için P.apiosperma izolatlarında MİK değerleri 0.5-> 8 arasında ve MEK 50 değeri de 1 olarak saptanmıştır. Aynı çalışmada, yine P.apiosperma suşları için amfoterisin ve posakonazol MİK aralıkları sırasıyla 0.5-> 16 µg/ml ve 0.25-> 16 µg/ml; MİK 50 değerleri de sırasıyla 8 ve 1 µg/ml olarak bulunmuştur 13 .…”

“…Lackner ve arkadaşlarının 13 çalışmasında, kaspofungin için P.apiosperma izolatlarında MİK değerleri 0.5-> 8 arasında ve MEK 50 değeri de 1 olarak saptanmıştır. Aynı çalışmada, yine P.apiosperma suşları için amfoterisin ve posakonazol MİK aralıkları sırasıyla 0.5-> 16 µg/ml ve 0.25-> 16 µg/ml; MİK 50 değerleri de sırasıyla 8 ve 1 µg/ml olarak bulunmuştur 13 . Bu sonuçlar MİK değerleri yönünden suş bazında farklılıkların tüm ilaçlarda gözlendiğini dü-şündürmektedir.…”

Commentaries: Name Changes in Medically Important Fungi and Their Implications for Clinical Practice

“…For example, Sporothrix schenckii, agent of human sporotrichosis, contains a hypervirulent sibling now known as Sporothrix brasiliensis causing large epidemics in Brazil (15). In another example, Scedosporium aurantiacum, one of the novel species recognized within the former umbrella species Scedosporium apiospermum is significantly less susceptible to currently used antifungal agents than the original species (16).…”

Latest Trends in Fungal Epidemiology Inform Treatment Choices and Stewardship Initiatives

“…For patients with some of the most difficult to treat fungal infections, caused by Scedosporium or Pseudallescheria species, in vitro susceptibility data suggest a potential therapeutic role for voriconazole, posaconazole and micafungin in Pseudallescheria apiosperma, Pseudallescheria boydii and Scedosporium prolificans infections [27], while for those with another therapeutic challenge -C. parapsilosis catheter infections -there was evidence from an animal model of the efficacy of anidulafungin, using the AF lock technique [28].…”