Agricultural systems as potential sources of emerging human mycoses caused by Trichoderma: a successful, common phylotype of Trichoderma longibrachiatum in the frontline

Trichoderma species are abundant in different agricultural habitats, but some representatives of this genus, mainly clade Longibrachiatum members are also emerging as causative agents of various human diseases with even fatal outcome. Strains of these species frequently show resistance to commonly used azole antifungals. Based on previous data it is hypothesized that Trichoderma isolates identified in human infections derive from environmental-including agricultural-origins. We examined Trichoderma longibrachiatum Rifai and Trichoderma bissettii Sandoval-Denis & Guarro strains recovered from four novel cases of human mycoses, along with isolates from previous case reports and different agricultural habitats, using multilocus phylogenetic analysis, BIOLOG Phenotype Microarrays and Etest. Strains attributed to T. bissettii were more abundant in both clinical and agricultural specimens compared to T. longibrachiatum. The majority of the isolates of both taxa could tolerate >256, >32 and >32 μg/ml fluconazole, itraconazole and posaconazole, respectively. None of the obtained results revealed characteristic differences between strains of clinical and agricultural origin, nor between the two taxa, supporting that agricultural environments may be significant sources of infections caused by these emerging human fungal pathogens. Furthermore, based on our findings we propose the re-classification of T. bissettii as T. longibrachiatum f. sp. bissettii.

Genotypes and population genetics of cryptococcus neoformans and cryptococcus gattii species complexes in Europe and the mediterranean area

A total of 476 European isolates (310 Cryptococcus neoformans var. grubii, 150 C. neoformans var. neoformans, and 16 C. gattii species complex) from both clinical and environmental sources were analyzed by multi-locus sequence typing. Phylogenetic and population genetic analyses were performed. Sequence analysis identified 74 sequence types among C. neoformans var. neoformans (VNIV), 65 among C. neoformans var. grubii (56 VNI, 8 VNII, 1 VNB), and 5 among the C. gattii species complex (4 VGI and 1 VGIV) isolates. ST23 was the most frequent genotype (22%) among VNI isolates which were mostly grouped in a large clonal cluster including 50% of isolates. Among VNIV isolates, a predominant genotype was not identified. A high percentage of autochthonous STs were identified in both VNI (71%) and VNIV (96%) group of isolates. The 16 European C. gattii species complex isolates analyzed in the present study originated all from the environment and all belonged to a large cluster endemic in the Mediterranean area. Population genetic analysis confirmed that VNI group of isolates were characterized by low variability and clonal expansion while VNIV by a higher variability and a number of recombination events. However, when VNI and VNIV environmental isolates were compared, they showed a similar population structure with a high percentage of shared mutations and the absence of fixed mutations. Also linkage disequilibrium analysis reveals differences between clinical and environmental isolates showing a key role of PLB1 allele combinations in host infection as well as the key role of LAC1 allele combinations for survival of the fungus in the environment. The present study shows that genetic comparison of clinical and environmental isolates represents a first step to understand the genetic characteristics that cause the shift of some genotypes from a saprophytic to a parasitic life style.

Environmental distribution of Cryptococcus neoformans and C. gattii around the Mediterranean basin

In order to elucidate the distribution of Cryptococcus neoformans and C. gattii in the Mediterranean basin, an extensive environmental survey was carried out during 2012-2015. A total of 302 sites located in 12 countries were sampled, 6436 samples from 3765 trees were collected and 5% of trees were found to be colonized by cryptococcal yeasts. Cryptococcus neoformans was isolated from 177 trees and C. gattii from 13. Cryptococcus neoformans colonized 27% of Ceratonia, 10% of Olea, Platanus and Prunus trees and a lower percentage of other tree genera. The 13 C. gattii isolates were collected from five Eucalyptus, four Ceratonia, two Pinus and two Olea trees. Cryptococcus neoformans was distributed all around the Mediterranean basin, whereas C. gattii was isolated in Greece, Southern Italy and Spain, in agreement with previous findings from both clinical and environmental sources. Among C. neoformans isolates, VNI was the prevalent molecular type but VNII, VNIV and VNIII hybrid strains were also isolated. With the exception of a single VGIV isolate, all C. gattii isolates were VGI. The results confirmed the presence of both Cryptococcus species in the Mediterranean environment, and showed that both carob and olive trees represent an important niche for these yeasts.

Prevalence of Pneumocystis jirovecii pneumonia (2010-2013): the first Croatian report

Pneumocystis jirovecii is an important cause of interstitial pneumonia particularly among immunocompromised hosts. We analysed the prevalence of P. jirovecii pneumonia (PCP) among HIV-infected and HIV-uninfected patients presented with interstitial pneumonia or acute respiratory syndrome hospitalized in six Croatian tertiary care hospitals. Over four-year period (2010-2013), a total of 328 lower respiratory tract samples: 253 (77.1%) bronchoalveolar lavage fluid, 43 (13.1%) tracheal aspirates and 32 (9.8%) bronchial aspirates from 290 patients were examined by real-time polymerase chain reaction (PCR). PCP was detected in 23 (7.9%) patients. The prevalence of PCP differed significantly among tested groups (χ2 = 95.03; d.f. = 3; p < 0.001). HIV-infected patients were more often positive (56.6%, 95%CI = 37.3-72.4) compared to other groups (patients with malignant disease 7.7%, 95%CI = 2.6-20.3; transplant patients 7.7%, 95%CI = 2.2-24.1; patients with other diagnosis 1.5%, 95%CI = 0.5-4.4). Majority of HIV-positive patients (80%) were newly diagnosed cases. Our results indicate that HIV-infected patients still represents the main risk group for P. jirovecii infection. PCP is responsible for pneumonia in 56.6% HIV-positive patients in Croatia, primarily those who do not know that they are HIV infected.

Hansenula anomala outbreak at a surgical intensive care unit: a search for risk factors

During a 5-month period, Hansenula anomala (H. anomala), an opportunistic fungus, caused an outbreak of infections in eight adult patients treated at a surgical intensive care unit (ICU). The source of the infections and route of transmission could not be identified. A case-control study included 32 patients treated simultaneously at the surgical ICU. Univariate analysis pointed to the following significant risk factors: blood alkalosis, reduced urea, duration of hospitalization, bacteremia and colonization with Pseudomonas aeruginosa, and an APACHE II score >17 (during bacteremia or fungemia). The stepwise logistic regression multivariate analysis showed only the duration of blood alkalosis to be significant in case patients.