Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determin...Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.展开更多
Pseudomonas aeruginosa is one of the most common pathogenic bacteria, frequently found in different environmental samples. The prevalence of multidrug resistant isolates has become an alarming concern for both patient...Pseudomonas aeruginosa is one of the most common pathogenic bacteria, frequently found in different environmental samples. The prevalence of multidrug resistant isolates has become an alarming concern for both patients and their surroundings. The present study was carried out to record prevalence of P. aeruginosa in surface water of Dhaka city and to screen their antibiotic resistance pattern. The study was also extended to typing of resistant isolates according to extended spectrum beta lactamase production. Hereby, Kirby-Bauer method was applied to test antibiotic sensitivity according to Clinical and Laboratory Standards Institute. Then, the Ampicillin resistant isolates were screened for ESBL production by Double Disk Synergy Test (DDST). In these prospects, 52 water samples were tested, of which 32 were found positive for P. aeruginosa isolates. Hundred percent of the positive isolates were found to Ampicillin (AMP) resistant followed by 93.7% to both Tetracycline and Gentamycin and 71.8% to Co-triimoxazole. P. aeruginosa is completely susceptible to third generation antibiotics ciprofloxacin, Imipenem and Aztreonam followed by moderately susceptible to Polymyxin-B (78.2%) and Colistin (87.5%). According to DDST, all of the susceptible isolates were found positive for AMC type beta-lactamase production. It is evident from this study that the surface water is contaminated with antibiotic resistant P. aeruginosa and that through the water systems antibiotic resistance can be transferred to humans and animals. So, appropriate and rationale use of antibiotic should be applied to minimize the emergence of multidrug isolates to environment.展开更多
Compared with channel estimation method based on explicit training sequences,bandwidth is saved for those methods using superimposed training sequences,while it is wasted when Cyclic Prefix(CP) is added.In previous wo...Compared with channel estimation method based on explicit training sequences,bandwidth is saved for those methods using superimposed training sequences,while it is wasted when Cyclic Prefix(CP) is added.In previous work of McLernon,the Mean Square Error(MSE) performance of Data-Dependent Superimposed Training(DDST) without CP for Single-Input Single-Output(SISO) system was analyzed under the assumption that the data-dependent sequence matrix was a circulant matrix and not interfered by others.In fact,for the system without CP,the data-dependent sequence matrix is not circulant any more and will be interfered.This paper derives the exact expression of MSE for the system without CP and also gives its extension to Multiple-Input Multiple-Output(MIMO) system without CP.展开更多
文摘Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.
文摘为提高信道估计与信号检测的精度且不增加系统频谱开销的情况下,在基于数据相关叠加训练序列方案(Data-De⁃pendent Superimposed Training,DDST)中加入降噪处理。发送端将导频与发送数据采用DDST方式叠加;接收端对估计的信道状态信息(Channel State Information,CSI)进行降噪处理,随后进行信号检测。仿真结果表明,在DDST系统中加入降噪处理能有效改善信道估计精度,从而进一步提高信号检测性能。
文摘Pseudomonas aeruginosa is one of the most common pathogenic bacteria, frequently found in different environmental samples. The prevalence of multidrug resistant isolates has become an alarming concern for both patients and their surroundings. The present study was carried out to record prevalence of P. aeruginosa in surface water of Dhaka city and to screen their antibiotic resistance pattern. The study was also extended to typing of resistant isolates according to extended spectrum beta lactamase production. Hereby, Kirby-Bauer method was applied to test antibiotic sensitivity according to Clinical and Laboratory Standards Institute. Then, the Ampicillin resistant isolates were screened for ESBL production by Double Disk Synergy Test (DDST). In these prospects, 52 water samples were tested, of which 32 were found positive for P. aeruginosa isolates. Hundred percent of the positive isolates were found to Ampicillin (AMP) resistant followed by 93.7% to both Tetracycline and Gentamycin and 71.8% to Co-triimoxazole. P. aeruginosa is completely susceptible to third generation antibiotics ciprofloxacin, Imipenem and Aztreonam followed by moderately susceptible to Polymyxin-B (78.2%) and Colistin (87.5%). According to DDST, all of the susceptible isolates were found positive for AMC type beta-lactamase production. It is evident from this study that the surface water is contaminated with antibiotic resistant P. aeruginosa and that through the water systems antibiotic resistance can be transferred to humans and animals. So, appropriate and rationale use of antibiotic should be applied to minimize the emergence of multidrug isolates to environment.
基金Supported by the National Natural Science Foundation of China (No.60772087,No.50803016,No.60975004,No.60902023)the Foundation for the Author of National Excellent Doctoral Dissertation of P.R. China (No.200341)+1 种基金the National 863 High-Tech R&D Program (No.2007AA01Z 228)the open research fund of Key Laboratory of Information Coding and Transmission,Southwest Jiaotong University
文摘Compared with channel estimation method based on explicit training sequences,bandwidth is saved for those methods using superimposed training sequences,while it is wasted when Cyclic Prefix(CP) is added.In previous work of McLernon,the Mean Square Error(MSE) performance of Data-Dependent Superimposed Training(DDST) without CP for Single-Input Single-Output(SISO) system was analyzed under the assumption that the data-dependent sequence matrix was a circulant matrix and not interfered by others.In fact,for the system without CP,the data-dependent sequence matrix is not circulant any more and will be interfered.This paper derives the exact expression of MSE for the system without CP and also gives its extension to Multiple-Input Multiple-Output(MIMO) system without CP.
