Tags

Type your tag names separated by a space and hit enter

Toxigenic properties and stx phage characterization of Escherichia coli O157 isolated from animal sources in a developing country setting.
BMC Microbiol. 2018 08 31; 18(1):98.BM

Abstract

BACKGROUND

In many Asian countries including Bangladesh E. coli O157 are prevalent in animal reservoirs and in the food chain, but the incidence of human infection due to E. coli O157 is rare. One of the reasons could be inability of the organism from animal origin to produce sufficient amount of Shiga toxin (Stx), which is the main virulence factor associated with the severe sequelae of infection. This study aimed to fill out this knowledge gap by investigating the toxigenic properties and characteristics of stx phage of E. coli O157 isolated from animal sources in Bangladesh.

RESULTS

We analysed 47 stx2 positive E. coli O157 of food/animal origin for stx2 gene variants, Shiga toxin production, presence of other virulence genes, stx phage insertion sites, presence of genes associated with functionality of stx phages (Q933 and Q21) and stx2 upstream region. Of the 47 isolates, 46 were positive for both stx2a and stx2d while the remaining isolate was positive for stx2d only. Reverse Passive Latex Agglutination assay (RPLA) showed that 42/47 isolates produced little or no toxin, while 5 isolates produced a high titre of toxin (64 to 128). 39/47 isolates were positive for the Toxin Non-Producing (TNP) specific regions in the stx2 promoter. Additionally, all isolates were negative for antiterminator Q933while a majority of isolates were positive for Q21 gene suggesting the presence of defective stx phage. Of the yehV and wrbA phage insertion sites, yehV was found occupied in 11 isolates while wrbA site was intact in all the isolates. None of the isolates was positive for the virulence gene, cdt but all were positive for hlyA, katP, etpD and eae genes. Isolates that produced high titre Stx (n = 5) produced complete phage particles capable of infecting multiple bacterial hosts. One of these phages was shown to produce stable lysogens in host strains rendering the Stx2 producing ability.

CONCLUSION

Despite low frequency in the tested isolates, E. coli O157 isolates in Bangladesh carry inducible stx phages and have the capacity to produce Stx2, indicating a potential risk of E. coli O157 infection in humans.

Authors+Show Affiliations

Enteric and Food Microbiology Laboratory, Laboratory Sciences and Services Division (LSSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka, 1212, Bangladesh.Enteric and Food Microbiology Laboratory, Laboratory Sciences and Services Division (LSSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka, 1212, Bangladesh. Present Address: Department of Biology, University of Vermont, Burlington, VT, 05405, USA.Enteric and Food Microbiology Laboratory, Laboratory Sciences and Services Division (LSSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka, 1212, Bangladesh.Enteric and Food Microbiology Laboratory, Laboratory Sciences and Services Division (LSSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka, 1212, Bangladesh. Present Address: Department of Mathematics and Natural Sciences, BRAC University, Mohakhali, Dhaka, 1212, Bangladesh.Enteric and Food Microbiology Laboratory, Laboratory Sciences and Services Division (LSSD), International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Mohakhali, Dhaka, 1212, Bangladesh. maislam@icddrb.org.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30170562

Citation

Rahman, Mahdia, et al. "Toxigenic Properties and Stx Phage Characterization of Escherichia Coli O157 Isolated From Animal Sources in a Developing Country Setting." BMC Microbiology, vol. 18, no. 1, 2018, p. 98.
Rahman M, Nabi A, Asadulghani M, et al. Toxigenic properties and stx phage characterization of Escherichia coli O157 isolated from animal sources in a developing country setting. BMC Microbiol. 2018;18(1):98.
Rahman, M., Nabi, A., Asadulghani, M., Faruque, S. M., & Islam, M. A. (2018). Toxigenic properties and stx phage characterization of Escherichia coli O157 isolated from animal sources in a developing country setting. BMC Microbiology, 18(1), 98. https://doi.org/10.1186/s12866-018-1235-3
Rahman M, et al. Toxigenic Properties and Stx Phage Characterization of Escherichia Coli O157 Isolated From Animal Sources in a Developing Country Setting. BMC Microbiol. 2018 08 31;18(1):98. PubMed PMID: 30170562.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Toxigenic properties and stx phage characterization of Escherichia coli O157 isolated from animal sources in a developing country setting. AU - Rahman,Mahdia, AU - Nabi,Ashikun, AU - Asadulghani,Md, AU - Faruque,Shah M, AU - Islam,Mohammad Aminul, Y1 - 2018/08/31/ PY - 2018/03/15/received PY - 2018/08/16/accepted PY - 2018/9/2/entrez PY - 2018/9/2/pubmed PY - 2019/5/17/medline KW - E. coli O157 KW - Shiga toxin 2 KW - Toxin non-producing KW - stx phage SP - 98 EP - 98 JF - BMC microbiology JO - BMC Microbiol VL - 18 IS - 1 N2 - BACKGROUND: In many Asian countries including Bangladesh E. coli O157 are prevalent in animal reservoirs and in the food chain, but the incidence of human infection due to E. coli O157 is rare. One of the reasons could be inability of the organism from animal origin to produce sufficient amount of Shiga toxin (Stx), which is the main virulence factor associated with the severe sequelae of infection. This study aimed to fill out this knowledge gap by investigating the toxigenic properties and characteristics of stx phage of E. coli O157 isolated from animal sources in Bangladesh. RESULTS: We analysed 47 stx2 positive E. coli O157 of food/animal origin for stx2 gene variants, Shiga toxin production, presence of other virulence genes, stx phage insertion sites, presence of genes associated with functionality of stx phages (Q933 and Q21) and stx2 upstream region. Of the 47 isolates, 46 were positive for both stx2a and stx2d while the remaining isolate was positive for stx2d only. Reverse Passive Latex Agglutination assay (RPLA) showed that 42/47 isolates produced little or no toxin, while 5 isolates produced a high titre of toxin (64 to 128). 39/47 isolates were positive for the Toxin Non-Producing (TNP) specific regions in the stx2 promoter. Additionally, all isolates were negative for antiterminator Q933while a majority of isolates were positive for Q21 gene suggesting the presence of defective stx phage. Of the yehV and wrbA phage insertion sites, yehV was found occupied in 11 isolates while wrbA site was intact in all the isolates. None of the isolates was positive for the virulence gene, cdt but all were positive for hlyA, katP, etpD and eae genes. Isolates that produced high titre Stx (n = 5) produced complete phage particles capable of infecting multiple bacterial hosts. One of these phages was shown to produce stable lysogens in host strains rendering the Stx2 producing ability. CONCLUSION: Despite low frequency in the tested isolates, E. coli O157 isolates in Bangladesh carry inducible stx phages and have the capacity to produce Stx2, indicating a potential risk of E. coli O157 infection in humans. SN - 1471-2180 UR - https://www.unboundmedicine.com/medline/citation/30170562/Toxigenic_properties_and_stx_phage_characterization_of_Escherichia_coli_O157_isolated_from_animal_sources_in_a_developing_country_setting_ L2 - https://bmcmicrobiol.biomedcentral.com/articles/10.1186/s12866-018-1235-3 DB - PRIME DP - Unbound Medicine ER -