Detection of Echinocandin-Resistant Candida glabrata in Blood Cultures Spiked with Different Percentages of FKS2 Mutants
Detection of Echinocandin-Resistant Candida glabrata in Blood Cultures Spiked with Different Percentages of FKS2 Mutants
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DOI：
10.1128/aac.02004-18
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发表时间：
2019-03-01
影响因子：
4.9
通讯作者：
Guinea, Jesus
中科院分区：
文献类型：
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作者：
Angeles Bordallo-Cardona, Maria;Sanchez-Carrillo, Carlos;Guinea, Jesus
光滑念珠菌棘白菌素耐药细胞和棘白菌素敏感细胞共存引起的感染可能是可能的，当FKS突变体的比例代表性不足时，FKS突变体的检测是一个问题。我们评估了EUCAST和直接在阳性血培养物上进行的方法-Etest（ETH）和含阿尼芬净的琼脂平板试验-在检测C.光滑念珠菌分离株含有不同量的棘白菌素敏感和耐药光滑念珠菌分离株。我们研究了10对C。光滑分离株，包括亲本棘白菌素敏感分离株和等基因棘白菌素抗性FKS突变分离株。制备每对三个接种物（1 × 10（3）至5 × 10（3）、1 × 10（2）至5 × 10（2）和10至50 CFU/ml），其中含有不同量的敏感/耐药分离株（三种接种物各为9/1、5/5和1/9比例）。将悬浮液加标于Bactec瓶中，孵育至阳性，并对三种方法进行比较。当瓶中加标5/5和1/9比例的敏感/耐药分离株时，EUCAST方法显示棘白菌素耐药性; 3对敏感/耐药分离株比例为9/1的混悬液的结果为敏感。我们观察到所有对中的ETC 4对两种棘白菌素的耐药性（对米卡芬净和阿尼芬净的耐药性; MIC分别为>= 0.064 mg/L和>= 0.125 mg/L），以及两对中的双环生长抑制。含阿尼芬净的平板在48 h时显示90个加标血培养物中有真菌生长。直接在阳性血培养瓶上用ETH检测棘白菌素敏感性是一种可靠、快速的检测棘白菌素耐药性的方法。光滑的另一方面，当耐药分离株代表性不足时，EU-CAST方法可能会遗漏耐药性。
Infections caused by the coexistence of Candida glabrata echinocandin-resistant and echinocandin-susceptible cells may be possible, and the detection of FKS mutants when the proportions of FKS mutants are underrepresented poses a problem. We assessed the role of EUCAST and methods directly performed on positive blood cultures-Etest (ETDIR) and anidulafungin-containing agar plate assays-for detecting resistance in C. glabrata isolates containing different amounts of echinocandin-susceptible and -resistant Candida glabrata isolates. We studied 10 pairs of C. glabrata isolates involving parental echinocandin-susceptible isolates and isogenic echinocandin-resistant FKS mutant isolates. Three inocula per pair (1 X 10(3) to 5 X 10(3), 1 X 10(2) to 5 X 10(2), and 10 to 50 CFU/ml) spanning suspensions with different amounts of susceptible/resistant isolates (9/1, 5/5, and 1/9 proportions for each the three inocula) were prepared. The suspensions were spiked in Bactec bottles and incubated until they were positive, and the three methods were compared. The EUCAST method showed echinocandin resistance when the bottles were spiked with susceptible/resistant isolates at 5/5 and 1/9 proportions; the results for the suspensions with a 9/1 proportion of susceptible/resistant isolates were susceptible for three pairs. We observed with the ETDIR resistance to both echinocandins in all pairs (resistance to micafungin and anidulafungin; MICs, >= 0.064 mg/liter and >= 0.125 mg/liter, respectively) and a double ring of growth inhibition in two pairs. The anidulafungin-containing plates showed fungal growth in the 90 spiked blood cultures at 48 h. Testing of echinocandin susceptibility with the ETDIR directly on the positive blood culture bottles is a reliable and rapid method to detect echinocandin resistance in C. glabrata. On the other hand, resistance can be missed with the EU-CAST method when resistant isolates are underrepresented.