Exploration And Establishment Of Scientific Research Systems For Yeasts Causing Invasive Fungal Infections From Multi-center Surveillance In China

[Objective]To investigate the epidemiology and antifungal susceptibility of yeast isolates causing invasive fungal infections collected from China Hospital Invasive Fungal Surveillance Net(CHIF-NET)study 2010-2014,and to establish a whole scientific research system of clinical important fungi including identification,antifungal susceptibility,typing,resistant mechanism and rare infection cases.[Methods]There were 65 hospitals participated in the CHIF-NET surveillance 2010-2014.All 9673 isolates collected were identified to species level by unique molecular identification methods,and antifungal susceptibility testing to fluconazole and voriconazole was performed by disk diffusion method.The evaluation of Vitek MALDI-TOF MS and Bruker Biotyper MALDI-TOF MS were performed in the isolates collected from CHIF-NET 2011 and 2013,respectively.Vitek 2 Compact YST card and API 20C AUX were used to compare the accuracy in identifyingCryptococcus laurentiiisolates.The capability of the popular used commercial kit ATB(?)FUNGUS 3 in antifungalsusceptibility testing was evaluated according to the golden method both microdilution.Several typing methods such as ITS and MLST were compared using Cryptococcusstrains.The relation between ERG11 genes and azoles resistance were investigated using Candida guilliermondii isolates.To firstly report the rare fungal infection case causing by C.quercitrusa.[Results]Of all 9673 isolates collected from CHIF-NET 2010 to 2014,70 species were identified totally.Comparing to molecular identification results,only 85.9%of initial identifications were correct.Candida species was predominant(91.3%),followed by Cryptococcus species(6.8%),Trichosporon species(0.8%)and other yeast species(1.2%).Candida albicans was the commonest Candida species(44.9%),whilst the non-albicans took more than 50%.Vitek MALDI-TOF MS v2.0identified96.7%isolates correctly to the species level,but Bruker Biotyper MALDI-TOF MS showed a better result of 98.8%,especially the Candida spp.(99.4%).By using CLSI disk diffusion testing,the resistant rates of Candida spp.tofluconazole and voriconazole were 8.8%and 3.8%,respectively.Candida albicans was the most sensitive species which resistant rate was less than 1%;C.parapsilosis complex also showed relative higher sensitivity of 90.8%tofluconazole and97.5%to voriconazole;the resistant(non-WT)rates of C.glabratatofluconazole and voriconazole were 19.0%and 18.7%,respectively;the resistance to both two antifungals increaseddramatically during the past five years,from 5%to above 20%.There were 26 Cryptococcus laurentiiisolates were identified by Vitek 2 Compact systems,however only two isolates(7.7%)were confirmed by ITS sequencing;whileAPI 20C AUX showed a better accuracy of 83.3%.The CA of ATB(?)FUNGUS 3 visual reading tofluconazole and voriconazole were95.5%and 95.4%,respectively;while the CA of ATB(?)FUNGUS 3 automatic reading were 77.2%and 73.3%,respectively.There were 12 ST types of Cryptococcus neoformans complexusing MLST method,ST5 accounted for 89.8%,followed by ST31;there were 5 ST types in Cryptococcus gattii.TheERG11 genes were amplified and sequenced in 164 Candida guilliermondiiisolates,16 genotypes were identified,some of them were closelyrelevant with azoles resistance.The C.quercitrusaisolates which caused human infections were firstly reported inthis study,and nosocomial infection outbreak of these three C.quercitrusastrains were confirmed in the ICU ward of Ha'erbin hospital.[Conclusions]The five years'CHIF-NET study has accumulated valuable micro-organism and clinical information sources.This study is a very important epidemiology and antifungal susceptibility study which involved the largest numbers of hospitals,isolates and longest time,It provided useful data to the field of invasive fungal infections previous we lack of knowledge.This study built up a scientific research system of clinical important fungi including identification,antifungal susceptibility,typing,resistant mechanism and rare infection cases,but there is still a long way to go.