1.First detection of Shiga toxin producing Escherichia coli O157:H7 (HlyA gene) and enumeration of most probable number (MPN) of fecal coliforms and Escherichia coli in cage cultured oysters (Crassostrea iredalei) and water from southern Malaysia
Tee Ka Hong ; George Bobby ; Nurshafiqah Norizan ; Nurshuhada Ariff ; Siti Nor Khadijah Addis ; Najiah Musa ; Sandra Catherine Zainathan
Malaysian Journal of Microbiology 2021;17(4):390-402
Aims:
Escherichia coli O157:H7 is known to be transmitted via fecal-oral route, where water plays a role in the
transmission process. Oysters as bivalves, bio accumulate pathogens from the water through filter feeding and are
suspected to play a role as disease transmission vector. In Malaysia, the data on oyster’s microbiological quality are
limited. Hence, it was vital to conduct oyster related studies in Malaysia. The main objectives of this study include the
enumeration of most probable number (MPN) of fecal coliforms and E. coli and isolation of E. coli from oyster
(Crassostrea iredalei) and water sample for the detection of 16S rRNA and HlyA (Hemolysin A) genes of E. coli
O157:H7.
Methodology and results:
A total of 120 oysters and water samples (n=6) were collected from a fisherman village
located in southern Malaysia. Total fecal coliforms and E. coli were determined using the MPN procedure. Colonies of E.
coli were identified based on Gram staining, biochemical test, and PCR detection for the presence of 16S rRNA and
HlyA gene of E. coli O157:H7. The enumeration results showed that the MPN of the fecal coliforms and E. coli found in
the collected oyster samples do not meet the standard to be directed for human consumption (0.72 ± 0.19 × 104
MPN/100 g and 0.13 ± 0.03 × 10
4 MPN/100 g, respectively). The PCR assays showed that 16 out of the 104 (15.38%) of
E. coli isolated from water and oysters showed the presence of HlyA gene. The phylogenetic tree analysis showed there
were genetic relationships between the HlyA gene of the E. coli isolated in this study with the ones isolated from calf and
human faeces.
Conclusion, significance and impact of study
The detection of Shiga toxin producing E. coli O157:H7 (HlyA gene) in
cage cultured oysters (C. iredalei) and water from southern Malaysia was first time reported here. In the future, more
study can be conducted to study the expression of the HlyA gene and confirm of its identity as E. coli O157:H7 using
different target genes such as eaeA (encodes a 94 kD outer membrane protein called intimin) and Stx1 (Shiga toxin,
Shigella dysenteriae type 1).
Escherichia coli O157
;
Crassostrea
2.A fluorometric method for direct detection of inorganic polyphosphate in enterohemorrhagic O157:H7.
Yanli DU ; Zongli HAN ; Xiangyu WANG ; Chengsong WAN
Journal of Southern Medical University 2019;39(3):344-350
OBJECTIVE:
To establish a quantitative fluorescent detection method using DAPI for detecting inorganic polyphosphate (polyP) in enterohemorrhagic Escherichia coli (EHEC) O157:H7.
METHODS:
The DNA of wild-type strain of EHEC O157:H7 was extracted and purified. DAPI was combined with the extracted DNA and polyP45 standards for measurement of the emission spectra at 360 nm and 415 nm fluorescence spectrophotometry. The fluorescence of DAPI-DNA and DAPI-polyP complexes was detected by fluorescence confocal microscopy to verify the feasibility of DAPI for detecting polyP. To determine the optimal pretreatment protocol for improving the cell membrane permeability, the effects of 6 pretreatments of the cells (namely snap-freezing in liquid nitrogen, freezing at -80 ℃, and freezing at -20 ℃, all followed by thawing at room temperature; heating at 60 ℃ for 10 min; treatment with Triton x-100; and placement at room temperature) were tested on the survival of EHEC O157:H7. The fluorescence values of the treated bacteria were then measured after DAPI staining. A standard calibration curve of polyP standard was established for calculation of the content of polyP in the live cells of wildtype EHEC strain and two mutant strains.
RESULTS:
At the excitation wavelength of 360 nm, the maximum emission wavelength of DAPI-DNA was 460 nm, and the maximum emission wavelength of DAPI-polyP was 550 nm at the excitation wavelength of 415 nm. The results of confocal microscopy showed that 405 nm excitation elicited blue fluorescence from DAPIDNA complex with the emission wavelength of 425-475 nm; excitation at 488 nm elicited green fluorescence from the DAPIpolyP complex with the emission wavelength of 500-560 nm of. Snap-freezing of cells at -80 ℃ followed by thawing at room temperature was the optimal pretreatment to promote DAPI penetration into the live cells. The standard calibration curve was =1849+127.5 (R=0.991) was used for determining polyP content in the EHEC strains. The experimental results showed that wild-type strain had significantly higher polyP content than the mutant strains with deletion.
CONCLUSIONS
We established a convenient quantitative method for direct and reliable detection polyP content to facilitate further study of polyP and its catalytic enzymes in EHEC O157:H7.
Escherichia coli O157
;
Escherichia coli Proteins
;
Polyphosphates
4.Studies on Virulence Factors and Application of Arbitrarily: primed Polymerase Chain Reaction Analysis to Epidemiological of Escherichia coli O157 : H7.
Journal of Bacteriology and Virology 2001;31(2):123-131
No abstract available.
Escherichia coli O157*
;
Escherichia coli*
;
Escherichia*
;
Polymerase Chain Reaction*
;
Virulence Factors*
;
Virulence*
6.Rapid Molecular Detection of Escherichia coli O157:H7.
Hyoung Shik SHIN ; Tae Geun OH ; Jong Sung SHIN ; Jung Hoon JI ; Bo Ra SON ; Kyeong Seob SHIN
Korean Journal of Infectious Diseases 2001;33(2):97-103
BACKGROUND: Sorbitol fermenting Escherichia coli O157 were reported. And E. coli O157:H7 produce various Shiga toxin (Stx) such as Stx1, Stx2, or variants of Stx2. In this study, we tried to establish laboratory methods that detect E. coli O157:H7 quickly and precisely by analyzing sensitivity of colony hybridization test and PCR technique. METHODS: Stx1-producing E. coli ATCC 43890, Stx2-producing E. coli ATCC 43889, and Stx2vha- producing E. coli ATCC 51435 were tested. Three strains of E. coli were diluted with 0.1 g of diarrheal stools from 107 CFU to 101 CFU respectively. The stool samples were incubated overnight in MacConkey agar plates. A mean of 63 colonies were hybridized by stx1- and stx2-specific oligonucleotide probes. PCR for stx1 gene and stx2 gene was done after overnight- incubation of stool samples in the LB broth with vancomycin (6 ug/mL). Positive colonies by colony hybridization were confirmed by PCR for stx1 gene and stx2 gene. RESULTS: Colony hybridization test could detect Stx1-producing E. coli at 103 CFU per 0.1 g of stool, Stx2-producing E. coli at 105 CFU per 0.1 g of stool, and Stx2vha-producing E. coli at 104 CFU per 0.1 g of stool. PCR technique after enrichment in LB broth with vancomycin (6 ug/mL) could detect stx1-, stx2-, and stx2vha-containing E. coli at 10 CFU per 0.1 g of stool respectively. CONCLUSOIN: A combination of colony hybridization and PCR after enrichment in broth with vancomycin (6 ug/mL) is useful for the rapid and precise diagnosis of infections of Shiga toxin-producing E. coli O157:H7.
Agar
;
Diagnosis
;
Escherichia coli O157
;
Escherichia coli*
;
Escherichia*
;
Oligonucleotide Probes
;
Polymerase Chain Reaction
;
Shiga Toxin
;
Sorbitol
;
Vancomycin
7.A Case of Escherichia coli O157 and Campylobacter species Gastroenteritis.
Young UH ; Soon Deok PARK ; Gyu Yul HWANG ; Kap Jun YOON ; Hwang Min KIM ; Hyo Youl KIM
Korean Journal of Clinical Microbiology 2004;7(2):186-189
Verotoxin-producing Escherichia coli O157 is a primary cause of severe and bloody diarrhea. Campylobacter spp. are one of the commonly reported bacterial cause of gastrointestinal infections throughout the world. Only a few cases involving both E. coli O157 and Campylobacter species have been reported. The authors simultaneously isolated verotoxin-producing E. coli O157 and Campylobacter species from the stool of a 3 year-old male with bloody diarrhea, fever and abdominal pain.
Abdominal Pain
;
Campylobacter*
;
Child, Preschool
;
Diarrhea
;
Escherichia coli O157*
;
Escherichia coli*
;
Escherichia*
;
Fever
;
Gastroenteritis*
;
Humans
;
Male
;
Shiga Toxins
;
Shiga-Toxigenic Escherichia coli
8.A Case of Escherichia coli O157 Hemorrhagic Colitis.
Seok Ho YOON ; Il Joong PARK ; Wee Gyo LEE
Korean Journal of Clinical Microbiology 2008;11(1):66-68
Escherichia coli O157 is an important serotype of enterohemorrhagic E. coli that causes hemorrhagic colitis worldwide. Outbreaks of E. coli O157 have been assocoated with contaminated food like meat, raw milk, and water, but recently vegetables and fruits have accounted for a growing number of recognized outbreaks. We isolated verotoxin producing E. coli O157 from the stool of a 3 year-old female with bloody diarrhea and abdominal pain. The child had been eating salad with vegetables and fruits frequently.
Abdominal Pain
;
Child
;
Colitis
;
Diarrhea
;
Disease Outbreaks
;
Eating
;
Enterohemorrhagic Escherichia coli
;
Escherichia
;
Escherichia coli
;
Escherichia coli O157
;
Female
;
Fruit
;
Humans
;
Meat
;
Milk
;
Shiga Toxins
;
Vegetables
9.Comparison of Detection of Escherichia coli O157 Between Culture After Acid Treatment and Polymerase Chain Reaction After Enrichment.
The Korean Journal of Laboratory Medicine 2002;22(5):331-335
BACKGROUND: The Polymerase Chain Reaction (PCR) for the Shiga toxin has been widely used for diagnosis of Shiga toxin-producing Escherichia coli (STEC) infection including Escherichia coli O157 (O157) instead of using a culture. However, bacteriological isolation must be followed for final diagnosis. Our study was aimed to compare the detection limit between the culture after the acid treatment and the PCR after enrichment. METHODS: The standard strain of O157 was cultured, diluted and mixed with the stool of normal adult in order to make a final concentration of the 10(1)-10(5) colony forming unit (CFU)/g of stool. Each concentration of samples was enriched in a trypticase soy broth for 6 hours at 42degrees C and treated with acid to suppress normal flora. Then it was streaked on cefixime-tellurite-sorbitol MacConkey (CT-SMAC) agar evenly and cultured for 18 hours at 37degrees C. The same concentrations of bacterial suspension in the stool were enriched in a Luria-Bertani (LB) broth overnight at 37degrees C. The centrifuged pellets from 1 mL of each concentration of the samples were boiled and DNA was extracted using the resin method and PCR was performed to amplify stx2. RESULTS: The detection limit for the culture after acid treatment was 10(3) CFU/g of the stool and that for PCR after enrichment was 101 CFU/g of the stool. CONCLUSIONS: Culture after acid treatment for O157 would be an effective method for isolation of O157 from a patient's stool. However, this method is less sensitive than the PCR after enrichment as far as detection limit is concerned. A combination of both methods would be an effective method for detecting O157 from patient stools.
Adult
;
Agar
;
Diagnosis
;
DNA
;
Escherichia coli O157*
;
Escherichia coli*
;
Escherichia*
;
Humans
;
Limit of Detection
;
Polymerase Chain Reaction*
;
Shiga Toxin
;
Shiga-Toxigenic Escherichia coli
;
Stem Cells
10.Construction and characterization of enterohemorrhagic Escherichia coli O157:H7 ppk- deleted strain.
Peng HAN ; Qi SUN ; Suhui ZHAO ; Qiwei ZHANG ; Chengsong WAN
Journal of Southern Medical University 2014;34(6):904-908
OBJECTIVETo construct enterohemorrhagic Escherichia coli (EHEC) O157: H7 ppk gene deletion strains and study its biological characteristics.
METHODSThe gene fragment of kanamycin resistance was amplified using a pair of homologous arm primers whose 5' and 3' ends were homologous with ppk gene and kanamycin resistance gene, respectively. EHEC O157: H7 EDL933w competent strains were prepared and transformed via electroporation with the amplification products. The ppk gene was replaced by kanamycin resistance gene using pKD46-mediated Red recombination system. The recombinant strain was confirmed by PCR and sequencing, and its morphology, growth ability and adhesion were assessed using Gram staining, OD600 value and Giemsa staining.
RESULTS AND CONCLUSIONWe established a ppk-deleted EHEC O157:H7 EDL933w strain with kanamycin resistance and compared the biological characteristics of the wild-type and mutant strains, which may facilitate further study of the regulatory mechanism of ppk gene.
DNA Primers ; Escherichia coli O157 ; genetics ; Escherichia coli Proteins ; genetics ; Gene Deletion ; Phosphotransferases (Alcohol Group Acceptor) ; genetics ; Polymerase Chain Reaction