Child ; China ; Diarrhea ; diagnosis ; microbiology ; Escherichia coli Infections ; diagnosis ; Humans ; Shiga-Toxigenic Escherichia coli ; isolation & purification

We encountered a patient with hemolytic uremic syndrome (HUS) with persistent isolation of shiga toxin-producing Escherichia coli (STEC) for 3 weeks despite of having no clinical symptoms. STEC has been recognized as an important food-borne pathogen that causes severe diseases such as HUS. We characterized this STEC strain via a polymerase chain reaction, reverse-passive latex agglutination and the slide agglutination method. In this STEC strain, stx2 (shiga toxin), eaeA, tir, iha (adherence genes), espADB (type III secretion genes), and hlyA, ehxA, clyA (hemolysin genes) were present. The O antigen of the strain was non-typable.
Child, Preschool ; Female ; Hemolytic-Uremic Syndrome/diagnosis/*microbiology ; Humans ; Shiga-Toxigenic Escherichia coli/*isolation & purification/*pathogenicity

OBJECTIVETraditional detection approaches for non-O157 STEC are both time and labour consuming in diseases surveillance. Virulence genes detection based on multiplex PCR could not only improve the detection efficiency but also increase the accuracy.

METHODSSix virulence genes of non-O157:H7 (stx1, stx2, eae, hly, etpD, katP6) were detected by two groups of trebling PCRs. The multiplex PCRs were optimized by melting curve analysis in SYBR Green I real-time PCR. Testing result of multiplex PCR was consistent with serological testing.

RESULTSThe sensitivity limits of the multiplex PCR for stx1, stx2, eaeP, etpD, katP, and hly were 10 ng/ml, 120 ng/ml, 110 ng/ml,165 ng/ml, 85 ng/ml, and 15 ng/ml, respectively, which is similar with that of single PCR. When the multiplex PCR was applied in 120 adults and 90 children diarrhea samples detection, 13 cases were detected for non-O157 positive.

CONCLUSIONThe method we established can be used for non-O157 STEC virulence genes detection and screening with high efficiency and accuracy.

Escherichia coli Infections ; diagnosis ; microbiology ; Escherichia coli Proteins ; genetics ; Humans ; Multiplex Polymerase Chain Reaction ; methods ; Shiga-Toxigenic Escherichia coli ; genetics ; isolation & purification ; Virulence Factors ; genetics

OBJECTIVETo establish a database and to understand the molecular epidemiological features of non-O157 Shiga toxin-producing Escherichia coli (STEC) isolates from different animal reservoirs and patients.

METHODSPulsed-field gel electrophoresis (PFGE) was performed according to the PulseNet protocol with minor modifications. A dendrogram was constructed using the BioNumerics.

RESULTSUnder the PulseNet protocol, 62 PFGE patterns were obtained from 76 non-O157 STEC isolates and then divided into A to M groups. Isolates from different sources were widely distributed in different groups, but were predominant seen in certain groups.

CONCLUSIONThe non-O157 STEC isolates in China were highly polymorphic. PulseNet protocol seemed to be suitable for the typing of Chinese non-O157 STEC isolates.

Animals ; China ; epidemiology ; DNA, Bacterial ; Electrophoresis, Gel, Pulsed-Field ; Escherichia coli Infections ; epidemiology ; microbiology ; Escherichia coli O157 ; genetics ; isolation & purification ; Feces ; microbiology ; Genotype ; Humans ; Shiga-Toxigenic Escherichia coli

A multiplex loop-mediated isothermal amplification (mLAMP) assay was developed for simultaneous detection of the stx1 and stx2 genes and applied for detection of shiga toxin-producing Escherichia coli (STEC) in cattle farm samples. Two target genes were distinguished based on T m values of 85.03 +/- 0.54degrees C for stx1 and 87.47 +/- 0.35degrees C for stx2. The mLAMP assay was specific (100% inclusivity and exclusivity), sensitive (with a detection limit as low as 10 fg/microL), and quantifiable (R 2 = 0.9313). The efficacy and sensitivity were measured to evaluate applicability of the mLAMP assay to cattle farm samples. A total of 12 (12/253; 4.7%) and 17 (17/253; 6.7%) STEC O157, and 11 (11/236; 4.7%) non-O157 STEC strains were isolated from cattle farm samples by conventional selective culture, immunomagnetic separation, and PCR-based culture methods, respectively. The coinciding multiplex PCR and mLAMP results for the types of shiga toxin revealed the value of the mLAMP assay in terms of accuracy and rapidity for characterizing shiga toxin genes. Furthermore, the high detection rate of specific genes from enrichment broth samples indicates the potential utility of this assay as a screening method for detecting STEC in cattle farm samples.
Animals ; Cattle ; Cattle Diseases/epidemiology/microbiology ; Escherichia coli Infections/epidemiology/microbiology/*veterinary ; Feces/microbiology ; Multiplex Polymerase Chain Reaction/veterinary ; Nucleic Acid Amplification Techniques/*veterinary ; Shiga Toxin 1/*genetics/isolation & purification ; Shiga Toxin 2/*genetics/isolation & purification ; Shiga-Toxigenic Escherichia coli/*genetics/isolation & purification