Predominance of Cryptococcus neoformans var. grubii multilocus sequence type 5 and emergence of isolates with non-wild-type minimum inhibitory concentrations to fluconazole: a multi-centre study in China

Abstract

There are few data on the molecular epidemiology of cryptococcosis in China. Here we investigated the species distribution, molecular types and antifungal susceptibilities of 312 Cryptococcus neoformans species complex isolates from ten hospitals over 5 years. Isolates were identified by internal transcribed spacer (ITS) sequencing and by two matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) systems. Multilocus sequence typing (MLST) was used to verify species/variety and to designate molecular types. Susceptibility to six antifungal drugs was determined by the Sensititre YeastOne™ method. Cryptococcus neoformans was the predominant species (305/312 isolates (97.8%), all were ITS type 1, serotype A), of which 89.2% (272/305) were C. neoformans var. grubii MLST sequence type (ST) 5 and 6.2% (19/305) were ST31. Other C. neoformans var. grubii STs were rare but included six novel STs. Only two strains were C. neoformans var. neoformans (both serotype AD). Cryptococcus gattii was uncommon (n = 7, four ITS types) and comprised five MLST STs including one novel ST. For C. neoformans var. grubii, the proportion of isolates with non-wild-type MICs to fluconazole significantly rose in the fourth study year (from 0% (0/56 isolates) in the first year to 23.9% (17/71) in the fourth year), including five isolates with fluconazole MICs of ≥32 mg/L. The study has provided useful data on the species epidemiology and their genetic diversity and antifungal susceptibility. The proportional increase in isolates with non-wild-type MICs to fluconazole is noted.

Cryptococcosis in patients with diabetes mellitus II in mainland China: 1993‐2015

“…MLST revealed that all seven clinical isolates in our study belonged to ST 5, which is in agreement with previous reports indicating that ST 5 is the predominant sequence type in China. [39][40][41][42] Antifungal susceptibility tests did not identify any resistant isolates.…”

Assessing the virulence ofCryptococcus neoformanscausing meningitis in HIV infected and uninfected patients in Vietnam

“…Most cases of cryptococcal meningitis in HIV uninfected, apparently immunocompetent, patients in Vietnam and East Asia are due to C. neoformans strains of multi-locus sequence type 5 (ST5) 9,10,12,17,26–28 . This phenomenon could be explained either by ST5 strains being intrinsically more pathogenic, or due to unidentified lineage–specific host immune defects or exposures.…”

“…Our clinical observations have been replicated in China, where >70% of CM cases from apparently immunocompetent individuals were infected with C. neoformans 10,11 . Again these organisms were latterly identified as genotype ST5 12,13 . Comparably, ST5 accounted for >80% of HIV-uninfected CM patients in South Korea, although some patients from this location had potentially immunosuppressive conditions 14 .…”

Multilocus Sequence Typing Reveals A Unique Co-Dominant Population Structure of Cryptococcus Neoformans Var. Grubii in Vietnam

“…In China, ST5 is the dominant ST, accounting for over 90% of infections [15,27,38]. While it is prevalent in both immunocompetent and immunocompromised patients, relatively few cases of HIV-associated disease have been reported [38].…”

“…Previous studies suggest there has been long distance dispersal of the species out of Africa [5,26]. Multilocus Sequence Typing (MLST) epidemiological studies from East Asia have shown limited genetic diversity among the majority of environmental and clinical isolates [19,27,28]. Despite the evidence of global dispersion at the species level[29,30], different geographical areas have distinct population structures, particularly in relation to the predominant sequence types[10].…”