EHEC: Scientists of Münster identify genome sequence of a comparable strain of the year 2001

Investigations shall deliver further indications as to the behavior of the current pathogen

Yesterday, Sunday 5th June, at 13:30 CET, scientists of the Medical Faculty of the University Münster and the University Hospital Münster finalized the whole genome sequencing of a historic EHEC (O104:H4) isolate that will be compared with the current German E. coli HUSEC041 (O104:H4) outbreak strain. Through comparison of both data records the team of scientists, led by Prof. Dr. Dr. h.c. Helge Karch, head of the Hygiene Institute at Münster´s University, hopes to achieve further valuable indications regarding the causes for the extreme aggressive behavior of the current outbreak strain.

Only some days ago, on 25th May the scientists of Münster were able to name and distinguish

HUSEC041 (O104:H4) being the current outbreak isolate. With the investigations taking place at present, the question most looked at is why and in which exact form this strain has altered compared with the isolates gained ten years ago; e.g. the current outbreak strain is resistant to a special class of antibiotics. The outbreak strain is not new and had already occurred earlier but is extremely rare. With this approach scientists of various institutions of the Medical Faculty Münster and the University Hospital Münster work together in close cooperation.

The microbiologist Prof. Dr. Dag Harmsen is conducting the team responsible for sequencing in Münster. The head of research of the Department of Periodontology in Münster explains the procedure: `The DNA of the current outbreak isolate has been submitted to scientists of the enterprise `Life Technology Corporation´ in Darmstadt who have carried out the genome sequencing. Now we have – in an almost impossible short time of just three days – deciphered the genome sequence of an historic 2001 isolate.´ Such a quick sequencing is to be considered `a scientific masterpiece, which will further contribute to the better understanding of the present outbreak and thereby finally assist to implement next steps to be taken in the sometimes very serious course of the disease with the patients affected´, explains Prof. Dr. Wilhelm Schmitz, Dean of the Medical Faculty of the University Münster.

To analyze the available results of both sequencings in comparison – exactly and with the utmost care – is now the main thing, adds Prof. Harmsen. Harmsen: `For now we have identified the letters but to understand the words or maybe the entire book of the genome, substantial expertise in biology as well as in bio-informatics is required in the analysis which is going on at present with all efforts thinkable we have at our hands. This analysis shall then be the fundamental for all further steps.´

For the moment, we do not – however – expect results from the analysis, which could be of immediate value as to diagnosis or therapy. We do hope to gain precious indications by the comparison of both genome sequences about what makes the outbreak strain so aggressive´, according to Dr. Alexander Mellmann of the `National Consulting Laboratory for Haemolytic Uraemic Syndrome (HUS) of the Robert Koch Institute’ at the Institute of Hygiene Münster.

Simultaneously with these research works further investigations are carried out under the supervision of Prof. Dr. Dr. h.c. Helge Karch for the better understanding and for the biological behavior of the current outbreak stain. Here questions about its already detected resistance against antibiotics or its behavior under special environmental conditions will be dealt with and are the center of the attention. The target is to achieve valuable hints about its natural reservoir. `These questions are important in order to remove the pathogen from the environment once the source of the infection and its reservoir has been located. It is of course our goal to avoid further outbreaks in the future´, says Prof. Karch.

Clues to editorial staff

As already published the present outbreak strain is an EHEC type belonging to the serogroup O104. On the 25th May, scientists of the University of Münster could already molecular-biologically prove `H4´ as the H-antigene. The so called `multilocus sequence type´ (MLST) is `ST678´. In the Münster reference collection of HUS-associated EHEC isolates, a `O104:H4´ serotype is distinguished as `HUSEC041´.

An overview regarding the HUSEC reference strain collection is provided under www.ehec.org. (`HUSEC-reference collection´).

There current laboratory information is available about the test procedures developed in Münster for the present outbreak strain (`Laborinfo´).