Latest Research News on Salmonella Typhimurium: Jan – 2020

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Latest Research News on Salmonella Typhimurium: Jan – 2020

January 2, 2020 Microbiology 0

Transformation of Salmonella typhimurium by Plasmid Deoxyribonucleic Acid

A modified transformation procedure that’s effective for the introduction of plasmid desoxyribonucleic acid at high frequency into Salmonella typhimurium , also as into Escherichia coli , is described. Transformed bacteria acquire a circular desoxyribonucleic acid species having the genetic and molecular characteristics of the reworking plasmid. [1]

Supramolecular Structure of the Salmonella typhimurium Type III Protein Secretion System

The type III secretion system of Salmonella typhimuriumdirects the translocation of proteins into host cells. Evolutionarily associated with the flagellar assembly machinery, this technique is additionally present in other pathogenic bacteria, but its organization is unknown. microscopy revealed supramolecular structures spanning the inner and outer membranes of flagellated and nonflagellated strains; such structures weren’t detected in strains carrying null mutations in components of the sort III apparatus. Isolated structures were found to contain a minimum of three proteins of this secretion system. Thus, the sort III apparatus of S. typhimurium, and presumably other bacteria, exists as a supramolecular structure within the bacterial envelope. [2]

Salmonella typhimurium invasion induces apoptosis in infected macrophages

Invasive Salmonella typhimurium induces dramatic cytoskeletal changes on the membrane surface of mammalian epithelial cells and RAW264.7 macrophages as a part of its entry mechanism. Noninvasive S. typhimurium strains are unable to induce this membrane ruffling. Invasive S. typhimurium strains invade RAW264.7 macrophages in 2 h with 7- to 10-fold higher levels than noninvasive strains. Invasive S. typhimurium and typhoid bacillus , independent of their ability to duplicate intracellularly, are cytotoxic to RAW264.7 macrophages and, to a greater degree, to murine bone marrow-derived macrophages. Here, we show that the macrophage cytotoxicity mediated by invasive Salmonella is apoptosis, as shown by nuclear morphology, cytoplasmic vacuolization, and host cell DNA fragmentation. S. typhimurium that enter cells causing ruffles but are mutant for subsequent intracellular replication also initiate host cell apoptosis. [3]

Recombinant attenuated Salmonella Typhimurium with heterologous expression of the Salmonella Choleraesuis O-polysaccharide: high immunogenicity and protection

Non-typhoidal Salmonella are related to gastrointestinal disease worldwide and invasive disease in Africa. We constructed novel bivalent vaccines through the recombinant expression of heterologous O-antigens from Salmonella Choleraesuis in Salmonella typhimurium . A recombinant Asd+ plasmid pCZ1 with the cloned Salmonella Choleraesuis O-antigen gene cluster was introduced into three constructed Salmonella typhimurium Δasd mutants: SLT11 (ΔrfbP), SLT12 (ΔrmlB-rfbP) and SLT16 (ΔrfbP ∆pagL::TT araCPBAD rfbP). Immunoblotting demonstrated that SLT11 (pCZ1) and SLT12 (pCZ1) efficiently expressed the heterologous O-antigen. within the presence of arabinose, SLT16 (pCZ1) expressed both the homologous and heterologous O-antigens, whereas within the absence of arabinose, SLT16 (pCZ1) mainly expressed the heterologous O-antigen. [4]

Multidrug Resistance Pattern of Salmonella Typhimurium Isolated from Rectal Swabs of Stray Dogs at Chittagong Metropolitan Area (CMA), Bangladesh

A cross-sectional study was conducted to research the prevalence and antimicrobial resistance pattern in Salmonella from 108 rectal swab of stray dogs of 9 randomly selected areas of Chittagong Metropolitan Area. Rectal swabs were collected for isolating Salmonella enterica serovar Typhimurium through bacteriological culture and InvA specific PCR assay followed by antimicrobial susceptibility testing. Out of the 108 samples, females showed higher prevalence (66.67%) than males (58.93%). Among the 67 bacterial culture positive isolates, 10.45% was Salmonella typhimurium in InvA gene specific PCR. Isolated Salmonella was tested for resistance to 12 different antimicrobial agents, using disc diffusion method. In cultural sensitivity test, 100% resistance was found against Amoxicillin where higher resistance was found against Azithromycin, Cefixime, Ampicilin and Pefloxacin. Gentamycin and Colistin seemed to be sensitive. [5]

Reference

[1] Lederberg, E.M. and Cohen, S.N., 1974. Transformation of Salmonella typhimurium by plasmid deoxyribonucleic acid. Journal of Bacteriology, 119(3), (Web Link)

[2] Kubori, T., Matsushima, Y., Nakamura, D., Uralil, J., Lara-Tejero, M., Sukhan, A., Galán, J.E. and Aizawa, S.I., 1998. Supramolecular structure of the Salmonella typhimurium type III protein secretion system. Science, 280(5363), (Web Link)

[3] Monack, D.M., Raupach, B., Hromockyj, A.E. and Falkow, S., 1996. Salmonella typhimurium invasion induces apoptosis in infected macrophages. Proceedings of the National Academy of Sciences, 93(18), (Web Link)

[4] Recombinant attenuated Salmonella Typhimurium with heterologous expression of the Salmonella Choleraesuis O-polysaccharide: high immunogenicity and protection
Xinxin Zhao, Qinlong Dai, Dekang Zhu, Mafeng Liu, Shun Chen, Kunfeng Sun, Qiao Yang, Ying Wu, Qingke Kong & Renyong Jia
Scientific Reports volume 7, (Web Link)

[5] Rakib, T., Islam, M. S., Nur-E-Azam, M., Islam, S., Faruq, A., Das, T., Akter, L., Hassan, M. and Hossain, M. (2018) “Multidrug Resistance Pattern of Salmonella Typhimurium Isolated from Rectal Swabs of Stray Dogs at Chittagong Metropolitan Area (CMA), Bangladesh”, Microbiology Research Journal International, 25(4), (Web Link)

 

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