Use of pulsed field gel electrophoresis genetic typing for tracing contamination with virulent Escherichia coli O157:H7 in beef-cattle producing farms

Akindolire, Muyiwa Ajoke; Ateba, Collins Njie

doi:10.1016/j.genrep.2018.08.011

Cited by 5 publications

(6 citation statements)

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“…The lytic profile of the isolated phages was determined against a total of 69 different environmental E. coli O157:H7 strains that were previously obtained and characterized [33]. The results in Table 4 showed that a large proportion (86.9%) of the environmental stains were resistant to phage activity since no plaques was formed when phages were spotted on the bacterial lawn.…”

Section: Lytic Profilementioning

confidence: 99%

Isolation and Characterisation of Bacteriophages with Lytic Activity Against Virulent <em>Escherichia coli</em> O157:H7: Potential Bio-Control Agents

Cn¹,

Ma²

2019

Preprint

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Bacteriophages can provide alternative measures for the control of E. coli O157:H7 that is currently an emerging food-borne pathogen of severe public health concern. This study was aimed at characterising E. coli O157:H7 specific phages as potential biocontrol agents for these pathogens. Fifteen phages were isolated and screened against 69 environmental E. coli O157:H7. Only 3 phages displayed broad lytic spectra against environmental shiga toxin-producing E. coli O157:H7 strains. These 3 lytic phages were designated V3, V7 and V8. Subsequent characterization indicated that they displayed very high degree of similarities despite isolation from different locations. Transmission Electron microscopy (TEM) of the phages revealed that they all had isometric heads of about 73 – 77 nm in diameter and short tails ranging from 20 - 25 nm in diameter. Phages V3, V7 and V8 were assigned to the family Podoviridae based on their morphology. Pulsed field gel electrophoresis (PFGE) genome estimation of the 3 phages demonstrated identical genome sizes of ~ 69 nm. The latent periods of these phages were 20 min, 15 min, and 20 min for V3, V7 and V8 respectively while the burst sizes were 374, 349 and 419 PFU/ infected cell respectively. While all the phages were relatively stable over a wide range of salinity, temperatures and pH values, their range of infectivity or lytic profile was rather narrow on environmental E. coli O157:H7 strains isolated from cattle faeces. This study showed that the Podoviridae bacteriophages are the dominant E. coli O57:H7-infecting phages harboured in cattle faeces in the North-West Province of South Africa and due to their favourable characteristics can be exploited in the formulation of phage cocktails for the bio-control of E. coli O157:H7 in meat and other meat products.

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Section: Lytic Profilementioning

confidence: 99%

Isolation and Characterisation of Bacteriophages with Lytic Activity Against Virulent <em>Escherichia coli</em> O157:H7: Potential Bio-Control Agents

Cn¹,

Ma²

2019

Preprint

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“…The genotypic profile of the major virulence genes of E. coli O157:H7 is quite variable in each isolate (Turkyilmaz et al ; Akindolire and Ateba, ). It is known that the infectious dose of E. coli O157:H7 is very low, at <100 organisms (Tuttle et al ; Thorpe ); thus, there is a high risk to the health of consumers in eating a RTE food, like sushi, contaminated with this pathogen, mainly when the isolate presents all these genes of virulence.…”

Section: Discussionmentioning

confidence: 99%

First report ofEscherichia coliO157:H7 in ready‐to‐eat sushi

et al. 2019

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Aims: The aim of this study was to evaluate the microbiological quality of commercially prepared ready-to-eat (RTE) sushi by enumerating aerobic mesophilic bacteria (AMB) and thermotolerant coliforms (TC) and detecting Escherichia coli and Salmonella ssp. An isolate was identified as E. coli O157:H7 which was evaluated for its virulence and antimicrobial resistance profiling as well as its ability to form biofilms on stainless steel. Methods and Results: There were four sampling events in seven establishments, totalling 28 pools of sushi samples. Mean AMB counts ranged between 5Á2 and 7Á7 log CFU per gram. The enumeration of TC varied between 2Á1 and 2Á7 log MPN per gram. Salmonella ssp. were not detected, and one sample was positive for E. coli and was identified as E. coli O157:H7. To the best of our knowledge, this is the first report of E. coli O157:H7 in sushi samples in the world literature. This isolate presented virulence genes stx1, stx2, eae and hlyA. It was also susceptible to 14 antimicrobials tested and had the ability to form biofilms on stainless steel. Conclusions: There is a need to improve the good hygiene practices adopted in establishments selling sushi in the city of Pelotas, Brazil. In addition, the isolated E. coli O157:H7 carries a range of important virulence genes being a potential risk to consumer health, as sushi is a RTE food. This isolate also presents biofilm formation ability, therefore, may trigger a constant source of contamination in the production line of this food. Significance and Impact of the Study: The increase in the consumption of sushi worldwide attracts attention regarding the microbiological point of view, since it is a ready-to-eat food. To our knowledge, this was the first time that E. coli O157:H7 was identified in sushi samples.

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“…The phage was capable of infecting virulent environmental Shiga toxin-producing E. coli (STEC) O157:H7 strains that were characterized in a previous report (9). Transmission electron micrographs of phage particles revealed an icosahedral head (75 ± 3.6 nm) and a short tail (23 ± 3.1 nm), as shown in Fig.…”

Section: Announcementmentioning

confidence: 94%