Multi-Resistant Aspergillosis due to Cryptic Species

Abstract

Reports of cryptic species causing aspergillosis in humans are increasing in the literature. Cryptic species are defined as those which are morphologically indistinguishable, although their identifications can be confirmed using molecular or other techniques which continue to become more widely available in the clinical setting. Antifungal resistance has often been noted in these cases, and indeed there does appear to be a higher prevalence of reduced susceptibility in cryptic species. Many of these observations are published as individual case reports or as a small component of larger data sets, making it challenging to review and compare the data fully. This review article seeks to describe the susceptibility trends and key learning outcomes of specific cases of infections caused by cryptic species, including Aspergillus alliaceus, Aspergillus calidoustus, Aspergillus felis, Aspergillus lentulus, Aspergillus tubingensis, Aspergillus viridinutans and Neosartorya pseudofischeri. These reports highlight the clinical need for full accurate identification and susceptibility testing to guide patient care.

Ecology of aspergillosis: insights into the pathogenic potency of Aspergillus fumigatus and some other Aspergillus species

“…Factors, such as increasing awareness among medical practitioners of the importance of the cryptic species (which in turn may lead to a greater research effort), ongoing development of improved techniques for species‐based identification, may also contribute to discrepancies between frequency reports for cryptic species. Some of the cryptic Aspergillus species show a decreased susceptibility to a large number of antifungal drugs when compared with other aspergilli (Alastruey‐Izquierdo et al ., , ; Howard, ; Nedel and Pasqualotto, ). Therefore, accurate identification of clinical isolates is critical for effective, targeted antifungal treatment (Alastruey‐Izquierdo et al ., , ).…”

“…Azole resistance is an emerging problem in A. fumigatus and other Aspergillus species, and is associated with an increased probability of treatment failure (Denning and Perlin, ; Seyedmousavi et al ., ). In addition, particular attention should be given to the increasing occurrence of cryptic species as these are typically linked to an increased antifungal resistance and different pathogenicity (Alastruey‐Izquierdo et al ., , ; Howard, ; Nedel and Pasqualotto, ). Furthermore, there is a strong appreciation that stress responses and biofilm formation are involved in drug adaptation, which can ultimately lead to development of higher‐level resistance and diminished clinical response (Kaur and Singh, ; Perlin et al ., ).…”

“… Cryptic species are those which can be differentiated using molecular or other analytical techniques and yet are morphologically indistinguishable (Howard et al ., ). …”

Advances Against Aspergillosis: Biology, Host response, Diagnosis and Treatment

“…Alastruey-Izquierdo et al [27] review the clinical relevance of these cryptic species, emphasizing their epidemiology and antifungal drug susceptibility profiles. The importance of accurate susceptibility testing as a way to guide patient care is further illustrated in the review by Howard [28], which explores the increasing frequency of multi-resistant cryptic species as etiologic agents of aspergillosis. Nedel and Pasqualotto [29] further highlight the complexities of identification and the importance of the susceptibility of cryptic species of Aspergillus to antifungal drugs and emphasize the paucity of organized clinical data on how to manage these unusual, yet emerging causes of aspergillosis.…”

Cryptic Aspergillus from clinical samples in the USA and description of a new species in section Flavipedes

“…Currently, Aspergillus has over 350 accepted species organised in subgenera and sections according to their morphological features and phylogenetic relationships . Many of them are considered cryptic species since they are difficult to differentiate from other related species by classical methods . Usually, when incapable of being identified, cryptic species are treated as a complex or are presumably identified as the most common pathogen of their section.…”