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Chen C.-Y.,CAS Institute of Electrical Engineering | Chen C.-Y.,University of Chinese Academy of Sciences | Chen C.-Y.,France China Bio Mineralization and Nano Structures Laboratory | Chen C.-F.,CAS Institute of Electrical Engineering | And 9 more authors.
Biomedical Microdevices | Year: 2014

Magnetotactic bacteria exhibit superiority over other bacteria in fabricating microrobots because of their high motility and convenient controllability. In this study, a microrobot system is constructed using magnetotactic bacteria MO-1 and applied in pathogenic separation. The feasibility of this approach is demonstrated using Staphylococcus aureus. The MO-1 magnetotactic bacterial microrobots are fabricated by binding magnetotactic bacteria MO-1 with their rabbit anti-MO-1 polyclonal antibodies. The efficient binding of MO-1 magnetotactic bacterial microrobots to Staphylococcus aureus is corroborated by phase contrast microscopic and transmission electron microscopic analyses. Further, a microfluidic chip is designed and produced, and the MO-1 microrobots are magnetically guided toward a sample pool in the chip. In the sample pool, Staphylococcus aureus samples are loaded on the microrobots and then carried away to a detection pool in the chip, suggesting the microrobots have successfully carried and separated pathogen. This study is the first to demonstrate bacterial microrobots carrying pathogens and more importantly, it reflects the great potential of using magnetotactic bacteria to develop magnetic-guided, auto-propelled microrobots for pathogen isolation. © 2014, Springer Science+Business Media New York. Source

Li B.,CAS Institute of Microbiology | Hu Y.,CAS Institute of Microbiology | Wang Q.,CAS Institute of Microbiology | Yi Y.,The 306 Hospital | And 4 more authors.
PLoS ONE | Year: 2013

Background:Klebsiella pneumoniae strains carrying class 1 integrons are becoming more common worldwide, and their role in the dissemination of drug resistance is significant. The aim of this study was to characterize the structural diversity of class 1 integrons and their associated gene cassettes in K. pneumoniae isolates from hospital settings.Methodology/Principal Findings:We analyzed a total of 176 K. pneumoniae isolates in a tertiary-care hospital in Beijing, China for the period of November 1, 2010-October 31, 2011. The presence of class 1 integrons and gene cassettes was analyzed by PCR and sequencing. The prevalence of class 1 integrons was 51.1% (90/176). Fourteen different gene cassettes and 10 different gene cassette arrays were detected. dfrA and aadA cassettes were predominant and cassette combination dfrA1-orfC was most frequently found (13.6%, 24/176). Strong association between resistance to a variety of drugs (both phenotypes and the associated genes) and the presence of class 1 integrons was observed. In addition, we also identified an association between some previously identified prevalent sequence types (such as ST11, ST15, ST147, ST562, and ST716) and the presence of class 1 integrons.Conclusions/Significance:Data from this study demonstrated that class 1 integrons are highly diverse and are associated with a variety of drug resistance phenotypes, drug resistance genes, as well as genotypes among K. pneumoniae isolates. Continuous monitoring of gene cassettes in class 1 integrons is warranted to improve the understanding and control of drug resistance among hospital settings. © 2013 Li et al. Source

Wang Q.,CAS Institute of Microbiology | Li B.,CAS Institute of Microbiology | Tsang A.K.L.,University of Hong Kong | Yi Y.,The 306 Hospital | And 2 more authors.
PLoS ONE | Year: 2013

Background: The genetic diversity and the clinical relevance of the drug-resistant Klebsiella pneumoniae isolates from hospital settings are largely unknown. We thus conducted this prospective study to analyze the molecular epidemiology of K. pneumoniae isolates from patients being treated in the 306 Hospital in Beijing, China for the period of November 1, 2010-October 31, 2011. Methodology/Principal Findings: Antibiotic susceptibility testing, PCR amplification and sequencing of the drug resistance-associated genes, and multilocus sequence typing (MLST) were conducted. A total of 163 isolates were analyzed. The percentage of MDR, XDR and PDR isolates were 63.8% (104), 20.9 (34), and 1.8% (3), respectively. MLST results showed that 60 sequence types (STs) were identified, which were further separated by eBURST into 13 clonal complexes and 18 singletons. The most dominant ST was ST15 (10.4%). Seven new alleles and 24 new STs were first identified in this study. Multiple logistic regression analysis revealed that certain clinical characteristics were associated with those prevalent STs such as: from ICU, from medical ward, from community acquired infection, from patients without heart disease, from patients with treatment success, susceptible to extended spectrum cephalosporin, susceptible to cephamycins, susceptible to fluoroquinolones, and with MDR. Conclusions/Significance: Our data indicate that certain drug-resistant K. pneumoniae clones are highly prevalent and are associated with certain clinical characteristics in hospital settings. Our study provides evidence demonstrating that intensive nosocomial infection control measures are urgently needed. © 2013 Wang et al. Source

Li B.,CAS Institute of Microbiology | Li B.,Shandong University | Yi Y.,The 306 Hospital | Wang Q.,CAS Institute of Microbiology | And 5 more authors.
PLoS ONE | Year: 2012

Background: The rates of multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR) isolates among Enterobacteriaceae isolates, particularly Klebsiella pneumoniae, have risen substantially worldwide. Methodology/Principal Findings: To better understand the molecular mechanisms of drug resistance in K. pneumoniae, we analyzed the drug resistance determinants for K. pneumoniae isolates collected from the 306 Hospital, a tertiary-care hospital in Beijing, China, for the period of September 1, 2010-October 31, 2011. Drug susceptibility testing, PCR amplification and sequencing of the drug resistance determinants were performed. Conjugation experiments were conducted to examine the natural ability of drug resistance to disseminate among Enterobacteriaceae strains using a sodium azide-resistant Escherichia coli J53 strain as a recipient. Among the 223 consecutive non-repetitive K. pneumoniae isolates included in this study, 101 (45.3%) were extended-spectrum beta-lactamases (ESBLs) positive. The rates of MDR, XDR, and PDR isolates were 61.4% (n = 137), 22.0% (n = 49), and 1.8% (n = 4), respectively. Among the tested drug resistance-associated genes, the following ones were detected at relatively high rates blaCTX-M-10 (80, 35.9%), aacC2 (73, 32.7%), dhfr (62, 27.8%), qnrS (58, 26.0%), aacA4 (57, 25.6%), aadA1 (56, 25.1%). Results from conjugation experiments indicate that many of the drug resistance genes were transmissible. Conclusions/Significance: Our data give a "snapshot" of the complex genetic background responsible for drug resistance in K. pneumoniae in China and demonstrate that a high degree of awareness and monitoring of those drug resistance determinants are urgently needed in order to better control the emergence and transmission of drug-resistant K. pneumoniae isolates in hospital settings. © 2012 Li et al. Source

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