Variable tellurite resistance profiles of clinically-relevant Shiga toxin-producing Escherichia coli (STEC) influence their recovery from foodstuffs

Kerangart, Stéphane; Douëllou, T.; Delannoy, Sabine; Fach, Patrick; Beutin, Lothar; Sergentet-Thevenot, D.; Cournoyer, Benoît; Loukiadis, Estelle

doi:10.1016/j.fm.2016.05.005

Cited by 16 publications

(21 citation statements)

References 46 publications

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“…Discussion K 2 TeO 3 has been used for over 100 years as a selective agent in media for the isolation of specific bacterial pathogens, e.g., Corynebacterium diphtheriae, Staphylococcus aureus, Vibrio cholerae, Shigella spp., and more recently, O157 STEC [16,22]. In addition, K 2 TeO 3 has been used to select for non-O157 STEC, but great variations in STEC tellurite susceptibilities exist among these organisms [12]. This variability in K 2 TeO 3 resistance, coupled with a lack of unique biochemical markers, has hampered development of highly effective selective media for non-O157 STEC [4,12,20], prompting the need for more research and the study conducted herein.…”

Section: Resultsmentioning

confidence: 99%

“…Essential to a functional ter operon, terD is a practical marker of its presence [10,13,17]. However, Kerangart et al [12] recently reported that although the ter operon is usually predictive of K 2 TeO 3 resistance in non-O157 STEC this is not always the case, and more research on the STEC tellurite resistome will be required for the development of improved media for the recovery of STEC.…”

Section: Introductionmentioning

confidence: 99%

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Tellurite Resistance in Shiga Toxin-Producing Escherichia coli

et al. 2018

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Potassium tellurite (KTeO) is an effective selective agent for O157:H7 Shiga toxin-producing Escherichia coli (STEC), whereas tellurite resistance in non-O157 STEC is variable with information on O45 minimal. High-level KTeO resistance in STEC is attributable to the ter gene cluster with terD an indicator of the cluster's presence. Polymerase chain reactions for terD and KTeO minimum inhibitory concentration (MIC) determinations in broth cultures were conducted on 70 STEC and 40 non-STEC control organisms. Sixty-six STEC strains (94.3%) were terD+ compared to 28 control organisms (70.0%; P < 0.001). The prevalence of terD in O103 STEC strains was 70%, whereas in all other serogroups it was ≥ 90%. The KTeO geometric mean MIC ranking for STEC serogroups from highest to lowest was O111 > O26 > O145 > O157 > O103 > O121 = O45. The KTeO geometric mean MIC was significantly higher in terD+ than in terD- STEC, but not in terD+ versus terD- control strains. Resistance to KTeO (MIC ≥ 25 mg/L) was exhibited by 65/66 terD+ and 0/4 terD- STEC strains, compared to 12/28 terD+ and 8/12 terD- control strains. These results confirm previous studies showing the significantly higher prevalence of the ter gene cluster in STEC strains, and the relationship between these genes and KTeO resistance in STEC and especially intimin (eae)-positive STEC, in contrast to non-STEC organisms. O45 and O121 STEC, although frequently terD positive, on average had significantly lower levels of KTeO resistance than O26, O111, and O145 STEC.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tellurite Resistance in Shiga Toxin-Producing Escherichia coli

et al. 2018

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“…The ter genes are commonly present in clinically relevant STEC isolates, including STEC O157:H7. However, some clinically relevant non-O157 STEC serogroups, such as O91 and O113, cannot grow on standard media containing 2.5 µg ml −1 of potassium tellurite [16, 22].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of chromogenic selective agar (CHROMagar STEC) for the direct detection of Shiga toxin-producing Escherichia coli from faecal specimens

Jenkins

Perry

Godbole

et al. 2020

Journal of Medical Microbiology

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Shiga toxin-producing Escherichia coli (STEC) are zoonotic pathogens that cause symptoms of severe gastrointestinal disease, including haemolytic uraemic syndrome (HUS), in humans. Currently in England, STEC serotypes other than O157:H7 are not cultured at the local hospital laboratories. The aim of this study was to evaluate the utility of CHROMagar STEC for the direct detection of STEC from faecal specimens in a diagnostic setting, compared to the current reference laboratory method using PCR targeting the Shiga-toxin gene (stx) to test multiple colonies cultured on MacConkey agar. Of the 292 consecutive faecal specimens submitted to the Gastrointestinal Bacterial Reference Unit that tested positive for stx by PCR, STEC could not be cultured on MacConkey agar or CHROMagar STEC from 87/292 (29.8 %). Of the 205 that were cultured, 106 (51.7 %) were detected on both MacConkey agar and CHROMagar STEC and 99 (48.3 %) were detected on MacConkey agar only. All 106 (100 %) isolates that grew on CHROMagar STEC had the ter gene cassette, known to be associated with resistance to tellurite, compared to 13/99 (13.1 %) that were not detected on CHROMagar STEC. CHROMagar STEC supported the growth of 36/40 (90 %) isolates harbouring stx2a or stx2d, the subtypes most frequently associated with progression to HUS. Of the 92 isolates harbouring eae, an important STEC virulence marker, 77 (83.7 %) grew on CHROMagar STEC. CHROMagar STEC is a useful selective media for the rapid, near-patient detection of STEC that have the potential to cause HUS.

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“…The STEC serotypes commonly associated with severe disease globally (O26, O45, O103, O111, O121, O145, and O157) [ 4 ] can readily be isolated on CHROMagar™STEC because they are commonly tellurite resistant [ 5 ]. Tellurite resistance is defined as growth at a minimum inhibitory concentration of 2.5 μg/ml to ≥20 μg/ml), [ 6 ] however the concentration of potassium tellurite in CHROMagar™STEC is proprietary. On this agar, the STEC serotypes that are commonly associated with severe human infections (O26, O45, O103, O111, O121, O145, and O157) [ 4 , 7 ] form mauve colonies, other Enterobacteriaceae form blue or colourless colonies, while the growth of gram-positive bacteria is inhibited ( http://www.chromagar.com/products-chromagar-stec-focus-on-stec-e-coli-51.html#.WNbR4vnyu01 ).…”

Section: Introductionmentioning

confidence: 99%

Characterisation of STEC and other diarrheic E. coli isolated on CHROMagar™STEC at a tertiary referral hospital, Cape Town

2018

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BackgroundShiga toxin producing E. coli (STEC) is an emerging zoonotic pathogen that can cause acute renal failure, especially in children. Clinical microbiology laboratories may fail to detect STEC and other diarrhoeic E. coli unless purposive rigorous screening procedures are followed using appropriate diagnostic technology; CHROMagar™STEC has rarely been used for isolation of African diarrhoeic E. coli hence characteristics of isolates on this medium are not yet fully understood. This study aimed to determine the prevalence and characteristics of STEC and other diarrhoeic E. coli isolated on CHROMagar™STEC from stool samples submitted to the microbiology laboratory of a South African public sector tertiary care hospital.ResultsIn total, 733 stool samples were tested. Of these, 4.5% (33/733) possessed diarrhoeic E. coli. Of the diarrheic E. coli, 5/33 (15.2%) were STEC, 15/33 (45.5%) EAggEC, 6/33 (18.2%) atypical EPEC, 5/33 (15.2%) typical EPEC, and 1/33 (3%) DAEC. None of the STEC isolates had been identified by routine testing (based on using sorbitol media to test for E. coli O157: H7 strains and not the other STEC) in the laboratory. Of the 33 strains, 55% (95% CI = 40.8–72.7) showed resistance to ampicillin.ConclusionsCHROMagar™STEC enabled detection of tellurite - resistant diarrhoeic E. coli that would be missed using routine methods. Further studies are needed to determine the proportion and characteristics of those which might have been missed using this approach.

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Variable tellurite resistance profiles of clinically-relevant Shiga toxin-producing Escherichia coli (STEC) influence their recovery from foodstuffs

Cited by 16 publications

References 46 publications

Tellurite Resistance in Shiga Toxin-Producing Escherichia coli

Tellurite Resistance in Shiga Toxin-Producing Escherichia coli

Evaluation of chromogenic selective agar (CHROMagar STEC) for the direct detection of Shiga toxin-producing Escherichia coli from faecal specimens

Characterisation of STEC and other diarrheic E. coli isolated on CHROMagar™STEC at a tertiary referral hospital, Cape Town

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