Genome assembly and copy-number analysis both confirmed that two copies of the Shiga toxin stx2 prophage gene cluster are a distinctive characteristic of the genome of the O104:H4 outbreak strain.[5][6]
The O104:H4 strain is characterized by these genetic markers:[6][7]
β-lactamases ampC, ampD, ampE, ampG, ampH are present.
The European Commission (EC) integrated approach to food safety[8] defines a case of Shiga-like toxin-producing E. coli (STEC) diarrhea caused by O104:H4 by an acute onset of diarrhea or bloody diarrhea together with the detection of the Shiga toxin 2 (Stx2) or the Shiga gene stx2.[9]
Prior to the 2011 outbreak, only one case identified as O104:H4 had been observed, in a woman in South Korea in 2005.[10]
Pathophysiology
E. coli O104 is a Shiga toxin–producing E. coli (STEC). The toxins cause illness and the associated symptoms by sticking to the intestinal cells and aggravating the cells along the intestinal wall.[11][12] This, in turn, can cause bloody stools to occur. Another effect from this bacterial infection is hemolytic uremic syndrome (HUS), which is a condition characterized by destruction of red blood cells, that over a long period of time can cause kidney failure.[13] Some common symptoms of HUS are vomiting, bloody diarrhea, and blood in the urine.[12]
Infection
A common mode of E. coli O104:H4 infection involves ingestion of fecally contaminated food; the disease can thus be considered a foodborne illness. Most recently in 2011, an outbreak of the O104:H4 strain in Germany caused the deaths of several people, and hundreds were hospitalised.[14][15][12] German authorities traced the infection back to fenugreek sprouts grown from contaminated seeds imported from Egypt, but these results are debated.[citation needed]
Diagnosis
To diagnose infection with STEC, a patient's stool (feces) can be tested in a laboratory for the presence of Shiga toxin. Testing methods used include direct detection of the toxin by immunoassay, or detection of the stx2 gene or other virulence-factor genes by PCR. If infection with STEC is confirmed, the E. coli strain may be serotyped to determine whether O104:H4 is present.[11]
Treatment
E. coli O104:H4 is difficult to treat as it is resistant to many antibiotics, although it is susceptible to carbapenems.[14]
Prevention
Spread of E. coli is prevented simply by thorough hand-washing with soap, washing and hygienically preparing food, and properly heating/cooking food, so the bacteria are destroyed.[16]
^"July 8, 2011: Outbreak of Shiga Toxin-producing E. Coli O104 (STEC O104:H4) Infections Associated with Travel to Germany | E. Coli." Centers for Disease Control and Prevention. Center for Disease Control and Prevention, 8 July 2011. Web. 08 Nov. 2011. <https://www.cdc.gov/ecoli/2011/ecolio104/>.
^"CDC - Escherichia coli O157:H7, General Information - NCZVED." Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 8 July 201. Web. 08 Nov. 2011.
