National Institute for Communicable Diseases (Centre for Healthcare-Associated Infections, Antimicrobial Resistance and Mycoses), a Division of the National Health Laboratory Service, Johannesburg, South Africa.
School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
PLoS Negl Trop Dis. 2022 Jun 29;16(6):e0010448. doi: 10.1371/journal.pntd.0010448. eCollection 2022 Jun.
As is the case globally, Cryptococcus gattii is a less frequent cause of cryptococcosis than Cryptococcus neoformans in South Africa. We performed multilocus sequence typing (MLST) and fluconazole susceptibility testing of 146 isolates randomly selected from 750 South African patients with C. gattii disease identified through enhanced laboratory surveillance, 2005 to 2013. The dominant molecular type was VGIV (101/146, 70%), followed by VGI (40/146, 27%), VGII (3/146, 2%) and VGIII (2/146, 1%). Among the 146 C. gattii isolates, 99 different sequence types (STs) were identified, with ST294 (14/146, 10%) and ST155 (10/146, 7%) being most commonly observed. The fluconazole MIC50 and MIC90 values of 105 (of 146) randomly selected C. gattii isolates were 4 μg/ml and 16 μg/ml, respectively. VGIV isolates had a lower MIC50 value compared to non-VGIV isolates, but these values were within one double-dilution of each other. HIV-seropositive patients had a ten-fold increased adjusted odds of a VGIV infection compared to HIV-seronegative patients, though with small numbers (99/136; 73% vs. 2/10; 20%), the confidence interval (CI) was wide (95% CI: 1.93-55.31, p = 0.006). Whole genome phylogeny of 98 isolates of South Africa's most prevalent molecular type, VGIV, identified that this molecular type is highly diverse, with two interesting clusters of ten and six closely related isolates being identified, respectively. One of these clusters consisted only of patients from the Mpumalanga Province in South Africa, suggesting a similar environmental source. This study contributed new insights into the global population structure of this important human pathogen.
与全球情况一样，在南非，隐球菌 gattii 是比新型隐球菌更不常见的隐球菌病病原体。我们对通过强化实验室监测于 2005 年至 2013 年期间在南非的 750 名隐球菌 gattii 病患者中随机挑选的 146 株分离株进行了多位点序列分型（MLST）和氟康唑药敏试验。主要的分子型为 VGIV（101/146，70%），其次是 VGI（40/146，27%）、VGII（3/146，2%）和 VGIII（2/146，1%）。在 146 株隐球菌 gattii 分离株中，鉴定出 99 种不同的序列型（ST），其中 ST294（14/146，10%）和 ST155（10/146，7%）最为常见。105 株（146 株中的 105 株）隐球菌 gattii 随机分离株的氟康唑 MIC50 和 MIC90 值分别为 4μg/ml 和 16μg/ml。与非 VGIV 分离株相比，VGIV 分离株的 MIC50 值较低，但两者相差一个稀释度。与 HIV 血清阴性患者相比，HIV 血清阳性患者发生 VGIV 感染的调整比值比为 10 倍，尽管病例数较少（99/136；73%比 2/10；20%），但置信区间（95%CI：1.93-55.31，p=0.006）较宽。对南非最常见的分子型 VGIV 的 98 株分离株的全基因组系统发育分析表明，该分子型具有高度多样性，分别鉴定出两个有趣的十个和六个密切相关的分离株簇。其中一个簇仅由南非 Mpumalanga 省的患者组成，提示存在类似的环境来源。本研究为该重要人类病原体的全球种群结构提供了新的见解。
