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Iqbal M.S.,Center for Food and Waterborne Diseases | Iqbal M.S.,Center for Control of Chronic Diseases | Rahman M.,Center for Food and Waterborne Diseases | Islam R.,Center for Food and Waterborne Diseases | And 4 more authors.
PLoS ONE | Year: 2014

In this study, mechanisms of plasmid-mediated sulfamethoxazole resistances in the clinical strains of multi-drug resistant (MDR) Shigella flexneri 2a were elucidated for the first time in Bangladesh. From 2006 to 2011, a total of 200 S. flexneri 2a strains were randomly selected from the stock of the Enteric and Food Microbiology Laboratory of icddr,b. Antimicrobial susceptibility of the strains showed 73%, 98%, 93%, 58%, 98%, 64% and 4% resistance to trimethoprim-sulfamethoxazole, nalidixic acid, ampicillin, erythromycin, tetracycline, ciprofloxacin and ceftriaxone respectively. Plasmid profiling revealed heterogeneous patterns and interestingly, all the trimethoprim- sulfamethoxazole resistant (SXTR) strains yielded a distinct 4.3 MDa plasmid compared to that of the trimethoprim-sulfamethoxazole susceptible (SXTS) strains. Curing of this 4.3 MDa plasmid resulted in the susceptibility to sulfamethoxazole alone suggesting the involvement of this plasmid in the resistance of sulfamethoxazole. Moreover, PCR analysis showed the presence of sul2 gene in SXTR strains which is absent in SXT S strains as well as in the 4.3 MDa plasmid-cured derivatives, confirming the involvement of sul2 in the resistance of sulfamethoxazole. Furthermore, pulsed-field gel electrophoresis (PFGE) analysis revealed that both the SXTR and SXTS strains were clonal. This study will significantly contributes to the knowledge on acquired drug resistance of the mostly prevalent S. flexneri 2a and further warrants continuous monitoring of the prevalence and correlation of this resistance determinants amongst the clinical isolates of Shigella and other enteric pathogens around the world to provide effective clinical management of the disease. © 2014 Iqbal et al.


Fakruddin M.,Bangladesh Institute of Technology | Mannan K.S.B.,Center For Food and Waterborne Diseases | Mazumdar R.M.,BCSIR Laboratories Chittagong | Afroz H.,Primeasia University
BMC Complementary and Alternative Medicine | Year: 2012

Background: There is wide spread interest in drugs derived from plants as green medicine is believed to be safe and dependable, compared with costly synthetic drugs that have adverse effects.Methods: We have attempted to evaluate the antioxidant, In vitro thrombolytic, antibacterial, antifungal and cytotoxic effects of Clausena heptaphylla (Rutaceae) stem bark extract ethanol extract.Results: Ethanolic stem bark extract of Clausena heptaphylla (CHET) contains flavonoids, alkaloids, saponins and steroids but it lacks tannins, anthraquinones and resins. Phenol content of the extract was 13.42 mg/g and flavonoid content was 68.9 mg/g. CHET exhibited significant DPPH free radical scavenging activity with IC50 value of 3.11 μg/ml. Reducing power of CHET was also moderately stronger. In the cytotoxicity assay, LC50 and Chi-square value of the ethanolic extract against brine shrimp nauplii were 144.1461 μg/ml and 0.8533 demonstrating potent cytotoxic effect of the extract. In vitro thrombolytic activity of CHET is significant with 45.38% clot lysis capability compared to that of Streptokinase (65.78%). In antibacterial screening, moderate zone of inhibition (6.5-9.0 mm in diameter) was observed against gram-positive Bacillus subtilis ATCC 11774, Bacillus cereus ATCC 10876, Staphylococcus aureus ATCC 25923, Bacillus polymyxa ATCC 842 and Bacillus megaterium ATCC 13578 and less promising zone of inhibition (3.0-4.5 mm in diameter) against gram-negative Salmonella typhi ATCC 65154, Shigella flexneri ATCC 12022, Proteus vulgaris ATCC 13315 and Escherichia coli ATCC 25922. Shigella sonnei ATCC 8992 did not show any sensitivity. The MIC values against these bacteria were ranged from 2,000 to 3,500 μg/ml. The extract showed significant zone of inhibition against Rhizopus oryzae DSM 2200, Aspergillus niger DSM 737 and Aspergillus ochraceus DSM 824 in antifungal assay.Conclusions: Further advanced research is necessary to isolate and characterize the chemical components responsible for the therapeutic properties of the plant. © 2012 Fakruddin et al.; licensee BioMed Central Ltd.


Fakruddin M.,Bangladesh Institute of Technology | Mannan K.S.B.,Center for Food and Waterborne Diseases | Chowdhury A.,Bangladesh Institute of Technology | Mazumdar R.M.,BCSIR Laboratories Chittagong | And 3 more authors.
Journal of Pharmacy and Bioallied Sciences | Year: 2013

Nucleic acid amplification is a valuable molecular tool not only in basic research but also in application oriented fields, such as clinical medicine development, infectious diseases diagnosis, gene cloning and industrial quality control. A comperehensive review of the literature on the principles, applications, challenges and prospects of different alternative methods of polymerase chain reaction (PCR) was performed. PCR was the first nucleic acid amplification method. With the advancement of research, a no of alternative nucleic acid amplification methods has been developed such as loop mediated isothermal amplification, nucleic acid sequence based amplification, strand displacement amplification, multiple displacement amplification. Most of the alternative methods are isothermal obviating the need for thermal cyclers. Though principles of most of the alternate methods are relatively complex than that of PCR, they offer better applicability and sensitivity in cases where PCR has limitations. Most of the alternate methods still have to prove themselves through extensive validation studies and are not available in commercial form; they pose the potentiality to be used as replacements of PCR. Continuous research is going on in different parts of the world to make these methods viable technically and economically.


Islam Z.,Center for Food and Waterborne Diseases | Islam Z.,Erasmus Medical Center | Gilbert M.,National Research Council Canada | Mohammad Q.D.,Dhaka Medical College Hospital | And 10 more authors.
PLoS ONE | Year: 2012

Background: Campylobacter jejuni is the predominant antecedent infection in Guillain-Barré syndrome (GBS). Molecular mimicry and cross-reactive immune responses to C. jejuni lipo-oligosaccharides (LOS) precipitate the development of GBS, although this mechanism has not been established in patients from developing countries. We determined the carbohydrate mimicry between C. jejuni LOS and gangliosides, and the cross-reactive antibody response in patients with GBS in Bangladesh. Methodology: Sera from 97 GBS patients, and 120 neurological and family controls were tested for antibody reactivity against LOS from C. jejuni isolates from GBS patients in Bangladesh (BD-07, BD-39, BD-10, BD-67 and BD-94) by enzyme-linked immunosorbent assay (ELISA). Cross-reactivity to LOS was determined by ELISA. The LOS outer core structures of C. jejuni strains associated with GBS/MFS were determined by mass spectrometry. Principle Findings: IgG antibodies to LOS from C. jejuni BD-07, BD-39, BD-10, and BD-67 IgG antibodies were found in serum from 56%, 58%, 14% and 15% of GBS patients respectively, as compared to very low frequency (<3%) in controls (p<0.001). Monoclonal antibodies specific for GM1 and GD1a reacted strongly with LOS from the C. jejuni strains (BD-07 and BD-39). Mass spectrometry analysis confirmed the presence of GM1 and GD1a carbohydrate mimics in the LOS from C. jejuni BD-07 and BD-39. Both BD-10 and BD-67 express the same LOS outer core, which appears to be a novel structure displaying GA2 and GD3 mimicry. Up to 90-100% of serum reactivity to gangliosides in two patients (DK-07 and DK-39) was inhibited by 50 μg/ml of LOS from the autologous C. jejuni isolates. However, patient DK-07 developed an anti-GD1a immune response while patient DK-39 developed an anti-GM1 immune response. Conclusion: Carbohydrate mimicry between C. jejuni LOS and gangliosides, and cross-reactive serum antibody precipitate the majority of GBS cases in Bangladesh. © 2012 Islam et al.


Akanda A.S.,University of Rhode Island | Jutla A.S.,West Virginia University | Gute D.M.,Tufts University | Sack R.B.,Johns Hopkins University | And 4 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2013

The highly populated floodplains of the Bengal Delta have a long history of endemic and epidemic cholera outbreaks, both coastal and inland. Previous studies have not addressed the spatio-temporal dynamics of population vulnerability related to the influence of underlying large-scale processes. We analyzed spatial and temporal variability of cholera incidence across six surveillance sites in the Bengal Delta and their association with regional hydroclimatic and environmental drivers. More specifically, we use salinity and flood inundation modeling across the vulnerable districts of Bangladesh to test earlier proposed hypotheses on the role of these environmental variables. Our results show strong influence of seasonal and interannual variability in estuarine salinity on spring outbreaks and inland flooding on fall outbreaks. A large segment of the population in the Bengal Delta floodplains remain vulnerable to these biannual cholera transmission mechanisms that provide ecologic and environmental conditions for outbreaks over large geographic regions. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene.


Dutta A.K.,Bangladesh Rice Research Institute BRRI | Dutta A.K.,University of Dhaka | Gope P.S.,Center for Food and Waterborne Diseases | Banik S.,Bangladesh Rice Research Institute BRRI | And 3 more authors.
Asian Pacific Journal of Tropical Biomedicine | Year: 2012

Objective: To study total phenolic content and antioxidant properties of 80% methanol extracts of ten high yielding rice varieties, five each from two different seasons namely aman and boro of Bangladesh. Methods: Total phenolic content was measured by Folin-Ciocalteau method while 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, hydroxyl ion scavenging, ferric reducing antioxidant power (Ferric reducing antioxidant power), and total antioxidant capacity (TAC) by ammonium molybdate, were used to analyze their Antioxidant properties. Results: Rice variaty BR5 of aman and BRRI dhan28 of boro season comparatively showed higher TPC and Antioxidant properties than the other rice varieties. BR22 of aman season showed the highest hydroxyl ion scavenging activity although it displayed the lowest TPC. Except for hydroxyl ion scavenging activity, aman rice varieties displayed comparatively higher total phenolic content and antioxidant property than the boro rice varieties. Conclusions: The results of the present study implies that the selected rice varieties possess moderate antioxidant capacity and therefore, can be considered as health supplements and nutraceuticals foods as rice is the staple food of Bangladesh. © 2012 Asian Pacific Tropical Biomedical Magazine.


Faruque S.M.,Center for Food and Waterborne Diseases | Faruque S.M.,University of Dhaka | Mekalanos J.J.,Harvard University
Virulence | Year: 2012

Understanding the genetic and ecological factors which support the emergence of new clones of pathogenic bacteria is vital to develop preventive measures. Vibrio cholerae the causative agent of cholera epidemics represents a paradigm for this process in that this organism evolved from environmental non-pathogenic strains by acquisition of virulence genes. The major virulence factors of V. cholerae, cholera toxin (CT) and toxin coregulated pilus (TCP) are encoded by a lysogenic bacteriophage (CTXφ) and a pathogenicity island, respectively. Additional phages which cooperate with the CTXφ in horizontal transfer of genes in V. cholerae have been characterized, and the potential exists for discovering yet new phages or genetic elements which support the transfer of genes for environmental fitness and virulence leading to the emergence of new epidemic strains. Phages have also been shown to play a crucial role in modulating seasonal cholera epidemics. Thus, the complex array of natural phenomena driving the evolution of pathogenic V. cholerae includes among other factors, phages that either participate in horizontal gene transfer or in a bactericidal selection process favoring the emergence of new clones? of V. cholerae. © 2012 Landes Bioscience.


Islam M.A.,Center for Food and Waterborne Diseases | Talukdar P.K.,Center for Food and Waterborne Diseases | Hoque A.,Center for Food and Waterborne Diseases | Huq M.,Center for Food and Waterborne Diseases | And 8 more authors.
European Journal of Clinical Microbiology and Infectious Diseases | Year: 2012

The main objective of this study was to investigate the prevalence of blaNDM-1 in Gram-negative bacteria in Bangladesh. In October 2010 at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) laboratories, 1,816 consecutive clinical samples were tested for imipenem-resistant Gram-negative organisms. Imipenem-resistant isolates were tested for the blaNDM-1 gene. Among 403 isolates, 14 (3.5%) were positive for blaNDM-1, and the predominant species were Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. All bla NDM-1-positive isolates were resistant to multiple antibiotics. Among β-lactamase genes, blaCTX-M-1-group was detected in ten isolates (eight blaCTX-M-15), blaOXA-1-group in six, blaTEM in nine, blaSHV in seven, and blaVIM and blaCMY in two isolates each. The 16S rRNA methylase gene, armA, was detected in fiveK. pneumoniae isolates and in one E. coli isolate. rmtB and rmtC were detected in a Citrobacter freundii and twoK. pneumoniae isolates, respectively. qnr genes were detected in twoK. pneumoniae isolates (one qnrB and one qnrS) and in an E. coli isolate (qnrA). Transferable plasmids (60-100 MDa) carrying blaNDM-1 were detected in 7 of the 11 plasmid-containing isolates. Pulsed-field gel electrophoresis (PFGE) analysis grouped K. pneumoniae isolates into three clusters, while E. coli isolates differed significantly from each other. This study reports that approximately 3.5% of Gram-negative clinical isolates in Bangladesh are NDM-1-producing. © Springer-Verlag 2012.


Faruque S.M.,Center for Food and Waterborne Diseases
Virulence | Year: 2012

Understanding the genetic and ecological factors which support the emergence of new clones of pathogenic bacteria is vital to develop preventive measures. Vibrio cholerae the causative agent of cholera epidemics represents a paradigm for this process in that this organism evolved from environmental non-pathogenic strains by acquisition of virulence genes. The major virulence factors of V. cholerae, cholera toxin (CT) and toxin coregulated pilus (TCP) are encoded by a lysogenic bacteriophage (CTXφ) and a pathogenicity island, respectively. Additional phages which cooperate with the CTXφ in horizontal transfer of genes in V. cholerae have been characterized, and the potential exists for discovering yet new phages or genetic elements which support the transfer of genes for environmental fitness and virulence leading to the emergence of new epidemic strains. Phages have also been shown to play a crucial role in modulating seasonal cholera epidemics. Thus, the complex array of natural phenomena driving the evolution of pathogenic V. cholerae includes, among other factors, phages that either participate in horizontal gene transfer or in a bactericidal selection process favoring the emergence of new clones of V. cholerae.


PubMed | Center for Food and Waterborne Diseases
Type: Journal Article | Journal: Virulence | Year: 2013

Understanding the genetic and ecological factors which support the emergence of new clones of pathogenic bacteria is vital to develop preventive measures. Vibrio cholerae the causative agent of cholera epidemics represents a paradigm for this process in that this organism evolved from environmental non-pathogenic strains by acquisition of virulence genes. The major virulence factors of V. cholerae, cholera toxin (CT) and toxin coregulated pilus (TCP) are encoded by a lysogenic bacteriophage (CTX) and a pathogenicity island, respectively. Additional phages which cooperate with the CTX in horizontal transfer of genes in V. cholerae have been characterized, and the potential exists for discovering yet new phages or genetic elements which support the transfer of genes for environmental fitness and virulence leading to the emergence of new epidemic strains. Phages have also been shown to play a crucial role in modulating seasonal cholera epidemics. Thus, the complex array of natural phenomena driving the evolution of pathogenic V. cholerae includes, among other factors, phages that either participate in horizontal gene transfer or in a bactericidal selection process favoring the emergence of new clones of V. cholerae.

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