Detection of Shiga toxin (Stx)-producing Escherichia coli (STEC) in bovine dairy herds in Northern Italy

Trevisani, Marcello; Mancusi, Rocco; Donne, G. Delle; Bacci, C.; Bassi, L.; Bonardi, S.

doi:10.1016/j.ijfoodmicro.2013.12.033

Cited by 24 publications

(21 citation statements)

References 27 publications

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“…Again, the presence of these free Stx phages might interfere with the analysis of food samples for contamination by STEC. Testing food samples for the presence of STEC using PCR targeting the stx gene can lead to a high amount of stx -positive samples ( ca 30%) which are not all subsequently confirmed by the isolation of STEC colony (Fach et al, 2001; Vernozy-Rozand et al, 2005; Madic et al, 2011; Trevisani et al, 2014). In addition, stx -negative E. coli also named attaching and effacing E. coli (AEEC) are also frequently isolated from foods (Anses, 2012; Trevisani et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Influence of Stress Factors Related to Cheese-Making Process and to STEC Detection Procedure on the Induction of Stx Phages from STEC O26:H11

et al. 2017

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Shiga toxin-producing Escherichia coli (STEC) are responsible for human infections, ranging from mild watery diarrhea to hemorrhagic colitis (CH) that may be complicated by hemolytic uremic syndrome (HUS). The main STEC virulence factor is Shiga toxin encoded by the stx gene, located in the genome of a bacteriophage integrated into the bacterial chromosome. The serotype O26:H11 is the second HUS-causing serotype worldwide (after O157:H7), and the first found in dairy products such as raw-milk cheeses. A small number of HUS cases identified each year in France are caused by serotype O26:H11. Stx phage induction is known to result in STEC lysis and release of new Stx phages particles. This phenomenon could negatively impact STEC screening in foods based on stx gene detection by PCR. Here, we evaluated the influence of physicochemical parameters related to cheese-making process on the induction rate of Stx phages from STEC O26:H11, including H2O2, NaCl, lactic acid and temperature. In addition, selective agents from the analytical STEC enrichment and detection procedure (XP CEN ISO/TS 13136) were tested, including novobiocin, acrifavin, cefixim-tellurite, and bile salts. An impact of H2O2 and NaCl on Stx phage induction was observed. Production of Stx phages was also observed during a real cheese-making process. By contrast, no significant effect could be demonstrated for the chemical agents of the STEC detection procedure when tested separately, except for acriflavin and novobiocin which reduced Stx1 phage production in some cases. In conclusion, these results suggest that the cheese-making process might trigger the production of Stx phages, potentially interfering with the analysis of STEC in food.

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Section: Introductionmentioning

confidence: 99%

Influence of Stress Factors Related to Cheese-Making Process and to STEC Detection Procedure on the Induction of Stx Phages from STEC O26:H11

et al. 2017

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“…An investigation to determine whether dairy beef cattle raised in Algeria are VTEC carriers show that samples from 61 (30.5%) animals out of the 200 tested are positive [15]. In Northern Italy, it is reported that of the bulk milk samples and milk filters collected in 193 dairy farms, Shiga toxin genes are detected in 30.2% of filters and 12.5% of milk samples [16]. While testing the quality of raw milk intends for direct consumption in Estonia, VTEC genes are detected in 64.3% of the on-line milk filter samples [17].…”

Section: Introductionmentioning

confidence: 99%

Detection of Verocytotoxigenic <i>Escherichia coli</i> O157 Serotype in Dairy Products in Abuja, Nigeria

Enem¹,

Oboegbulem²,

Nafarnda³

et al. 2015

OJVM

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Ruminants are recognized as healthy carriers of Verocytotoxigenic Escherichia Coli (VTEC) organisms and as such most dairy products may provide these bacteria with favourable conditions for their growth. A cross sectional study was conducted to detect the occurrence of VTEC O157 in dairy products in the Federal Capital Territory, Abuja, Nigeria. Raw milk, Nunu and yoghurt were analyzed using standard cultural and biochemical procedures to isolate typical E. coli. Isolated E. coli samples were sub-cultured into plates of sorbitol MacConkey and Cefixime Tellurite-Sorbitol MacConkey agar. Isolates that are sorbitol negative were further characterized using commercially procured latex agglutination test kits. A total of 367 samples were analyzed out of which 3 tested positive for VTEC O157 (108 of raw milk -1 (0.93%); 127 of Nunu -2 (1.57%) and 132 of yoghurt -none). There was no significant association (p > 0.05) between season and infection with VTEC O157 in dairy products. Dairy products remained a potential vehicle for VTEC O157 infection.

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“…Stx phage transfer can result in the emergence of new highly pathogenic strains as illustrated by the recent outbreak in Germany in 2011, with nearly 4,000 humans infected, including 900 HUS cases and 50 deaths (30), which was caused by an enteroaggregative E. coli O104:H4 strain lysogenized with an Stx phage (31). Phage-mediated transfer of the stx 2 gene to E. coli has also been shown to occur in food and water samples (32 (35). The fact that stx-negative E. coli (or AEEC) O26:H11 strains could be isolated from stx-positive food samples raises some questions about the diagnostic result since the possibility that these strains are derivatives of STEC that have lost their Stx phage and hence their stx gene during the enrichment procedure or isolation step cannot be excluded.…”

mentioning

confidence: 99%

Heterogeneity in Induction Level, Infection Ability, and Morphology of Shiga Toxin-Encoding Phages (Stx Phages) from Dairy and Human Shiga Toxin-Producing Escherichia coli O26:H11 Isolates

Bonanno

Petit

Loukiadis

et al. 2016

Appl Environ Microbiol

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e Shiga toxin (Stx)-producing Escherichia coli (STEC) bacteria are foodborne pathogens responsible for diarrhea and hemolyticuremic syndrome (HUS). Shiga toxin, the main STEC virulence factor, is encoded by the stx gene located in the genome of a bacteriophage inserted into the bacterial chromosome. The O26:H11 serotype is considered to be the second-most-significant HUScausing serotype worldwide after O157:H7. STEC O26:H11 bacteria and their stx-negative counterparts have been detected in dairy products. They may convert from the one form to the other by loss or acquisition of Stx phages, potentially confounding food microbiological diagnostic methods based on stx gene detection. Here we investigated the diversity and mobility of Stx phages from human and dairy STEC O26:H11 strains. Evaluation of their rate of in vitro induction, occurring either spontaneously or in the presence of mitomycin C, showed that the Stx2 phages were more inducible overall than Stx1 phages. However, no correlation was found between the Stx phage levels produced and the origin of the strains tested or the phage insertion sites. Morphological analysis by electron microscopy showed that Stx phages from STEC O26:H11 displayed various shapes that were unrelated to Stx1 or Stx2 types. Finally, the levels of sensitivity of stx-negative E. coli O26:H11 to six Stx phages differed among the 17 strains tested and our attempts to convert them into STEC were unsuccessful, indicating that their lysogenization was a rare event.

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Detection of Shiga toxin (Stx)-producing Escherichia coli (STEC) in bovine dairy herds in Northern Italy

Cited by 24 publications

References 27 publications

Influence of Stress Factors Related to Cheese-Making Process and to STEC Detection Procedure on the Induction of Stx Phages from STEC O26:H11

Influence of Stress Factors Related to Cheese-Making Process and to STEC Detection Procedure on the Induction of Stx Phages from STEC O26:H11

Detection of Verocytotoxigenic <i>Escherichia coli</i> O157 Serotype in Dairy Products in Abuja, Nigeria

Heterogeneity in Induction Level, Infection Ability, and Morphology of Shiga Toxin-Encoding Phages (Stx Phages) from Dairy and Human Shiga Toxin-Producing Escherichia coli O26:H11 Isolates

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Detection of Shiga toxin (Stx)-producing Escherichia coli (STEC) in bovine dairy herds in Northern Italy

Cited by 24 publications

References 27 publications

Influence of Stress Factors Related to Cheese-Making Process and to STEC Detection Procedure on the Induction of Stx Phages from STEC O26:H11

Influence of Stress Factors Related to Cheese-Making Process and to STEC Detection Procedure on the Induction of Stx Phages from STEC O26:H11

Detection of Verocytotoxigenic &lt;i&gt;Escherichia coli&lt;/i&gt; O157 Serotype in Dairy Products in Abuja, Nigeria

Heterogeneity in Induction Level, Infection Ability, and Morphology of Shiga Toxin-Encoding Phages (Stx Phages) from Dairy and Human Shiga Toxin-Producing Escherichia coli O26:H11 Isolates

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Detection of Verocytotoxigenic <i>Escherichia coli</i> O157 Serotype in Dairy Products in Abuja, Nigeria