Invasive fungal infections are associated with high mortality and morbidity rates, especially in immunocompromised and critically ill patients (1-3). Although the most important causes of opportunistic mycoses are Candida species, especially Candida albicans, the incidence of invasive fungal infections due to nonalbicans Candida species is increasing, especially in China (4-8).The National China Hospital Invasive Fungal Surveillance Net (CHIF-NET) program is a nationwide, multicenter surveillance network established in July 2009 to provide updated information on the epidemiology of invasive fungal infections in China (9). The continual expansion of the CHIF-NET program has led to a dramatic increase in the number of laboratories submitting isolates. Therefore, an accurate, time-saving, cost-effective, and userfriendly yeast identification method is needed to replace the highcost and labor-intensive sequence-based methods used by the central laboratory.Several studies have reported that matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is an accurate, rapid, and inexpensive method for identification of clinically relevant yeasts (10, 11). In our previous study, we evaluated the performance of the Vitek MS system (bioMérieux, France) for identifying yeast isolates collected as part of the CHIF-NET program in 2011 (12). In the present study, we further systematically compared the performance of the Bruker Biotyper MS (Bruker Daltonics GmbH, Germany) and the Vitek MS systems for the identification of a large number of clinically relevant yeast isolates collected through the CHIF-NET program (2012 to 2013).(This study was presented in part at the 19th Congress of the International Society for Human and Animal Mycology (ISHAM), Melbourne, Australia, 2015.)The 2,683 yeast isolates analyzed in this study were all derived from patients with invasive candidiasis from 48 clinical microbiology laboratories of hospitals situated in 24 provinces across China during the period August 2012 to July 2013. The majority of the nonduplicate isolates were obtained from blood (44.2%), followed by ascitic fluid (18.2%), intravascular catheters (7.6%), pus (7.3%), and cerebrospinal fluid (5.9%) (see Table S1 in the supplemental material). The isolates were inoculated onto CHROMagar Candida medium (CHROMagar, Paris, France), incubated for 48 h at 35°C, and then simultaneously identified using the Vitek MS and Bruker Biotyper MS systems.For the Vitek MS v.2.0 system, proteins were extracted as recommended by the manufacturer. Briefly, a small portion of a single colony was directly spotted onto a target plate and covered with 0.5 l of formic acid (bioMérieux). All mass profiles were analyzed using the Vitek MS database (MS-ID v.2.0 knowledge base clinical use). For the Bruker Biotyper MS system, pure yeast isolates (each from a single colony), were directly smeared onto the target plate (Bruker Daltonics GmbH) and overlaid with 1 l of 70% formic acid (Sigma-Aldrich). Each spectrum was analyzed by ...
Clostridium difficile hyper-virulent ribotype 027 strain has become a significant concern globally, but has rarely been reported in Asian countries including China. Recently, a retrospective single-center study in Beijing, China, detected two ribotype 027 C. difficile isolates from two patients coming for outpatient visits in 2012 and 2013. We performed a systematic investigation of the two isolates (and patients). Both C. difficile isolates had the typical PCR ribotype 027 profile; were positive for tcdA, tcdB and binary toxin genes; belonged to multilocus sequence type 1 (ST1); had typical ribotype 027 deletions in the tcdC gene; and were highly-resistant to fluoroquinolones; but had a different MLVA profile and were not genetically related to any previously reported international ribotype 027 clones. A review of the patients’ medical records showed that neither received appropriate antimicrobial treatment and were lost to follow-up after outpatient visits. We propose that C. difficile infections caused by ribotype 027 are probably a neglected problem in China, and the subsequent impact of unawareness of this problem is worrying. Appropriate testing assays and multi-center or national level surveillance for C. difficile infections and specifically for ribotype 027 should be introduced to provide essential data and guide future clinical practice.
While the developed world has seen a significant increase in the number of scientific articles on Clostridium difficile infection (CDI), the developing world still lags behind on this subject due to limited laboratory capacity, low awareness, and limited surveillance of this problem. As such, CDI is considered a neglected but potentially huge problem in developing countries. The major aim of this study was to systemically evaluate the utility of several molecular typing tools for CDI, including their relevance in epidemiological studies in developing countries such as China. A total of 116 non-repetitive toxigenic C. difficile isolates from Chinese patients, were studied. The isolates comprised 83 (71.6%) A+B+CDT- isolates, 27 (23.3%) A-B+CDT- isolates, and 6 (5.1%) A+B+CDT+ isolates. Typing methods evaluated included multilocus variable-number tandem-repeat analysis, PCR ribotyping, multilocus sequence typing, and sequencing of slpA and tcdC genes, which identified 113, 30, 22, 18, and 8 genotypes each and exhibited discriminatory powers of 0.999, 0.916, 0.907, 0.883, and 0.765, respectively. Compared to A+B+ strains, A-B+ strains exhibited higher prevalence of drug resistance to clindamycin, erythromycin, levofloxacin, rifampicin, rifaximin, and tetracycline. Furthermore, drug resistance rates of strains with different PCR ribotypes differed, supporting the importance of molecular typing in management and control of CDI. Based on our earlier suggestion to improve the diagnostic laboratory capacity of CDI in developing countries, setting up efficient surveillance programs complemented by relevant molecular typing methods is warranted.
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