Tellurite Resistance in Shiga Toxin-Producing Escherichia coli

• Published in: Current microbiology Vol. 75; no. 6; pp. 752 - 759
• Main Authors: Lewis, Gentry L., Jorgensen, Quentin R., Loy, John D., Moxley, Rodney A.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2018; Springer Nature B.V
• Subjects: Bacteria; Biomedical and Life Sciences; Biotechnology; Drug resistance; E coli; Escherichia coli; Intimin; Life Sciences; Microbial Sensitivity Tests; Microbiology; Minimum inhibitory concentration; Organisms; Polymerase chain reaction; Potassium tellurite; Shiga toxin; Shiga-Toxigenic Escherichia coli - drug effects; Shiga-Toxigenic Escherichia coli - genetics; Strains (organisms); Tellurite; Tellurium - pharmacology; Tellurium dioxide; Ter gene; Toxins
• ISSN: 0343-8651; 1432-0991
• DOI: 10.1007/s00284-018-1444-x

Potassium tellurite (K 2 TeO 3 ) 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 K 2 TeO 3 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 K 2 TeO 3 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 K 2 TeO 3 geometric mean MIC ranking for STEC serogroups from highest to lowest was O111 > O26 > O145 > O157 > O103 > O121 = O45. The K 2 TeO 3 geometric mean MIC was significantly higher in terD + than in terD − STEC, but not in terD + versus terD − control strains. Resistance to K 2 TeO 3 (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 K 2 TeO 3 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 K 2 TeO 3 resistance than O26, O111, and O145 STEC.