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Severe gastrointestinal infections caused by marine bacteria

Severe gastrointestinal infections caused by marine bacteria


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This is how pathological bacteria spread in the sea

In recent years there have been repeated reports of increased infections with the bacterium Vibrio parahaemolyticus, which settles in the coastal areas of the seas and can represent an unnoticed danger when bathing. A recent study by the Max Planck Institute for Terrestrial Microbiology in Marburg has now made it clear how the bacteria spread in coastal waters.

"A special type of cell in the bacteria enables it to spread under the changing environmental conditions of the tidal zone," reports the research team led by Simon Ringgaard of his study results. So-called "adventurer" cells are responsible for the spread of the pathogen. The results of the current study were published in the specialist magazine "The ISME Journal".

Propagation of the vibrions

According to the researchers, bacteria of the Vibrio parahaemolyticus genus are the main cause of gastrointestinal infections in humans. The number of Vibrio infections, especially in Central and Northern Europe, has increased significantly recently or is likely to increase in the near future. The research team cites global trade and the higher water temperatures resulting from climate change as possible reasons.

Marine animals are potential carriers

"Mussels, oysters and crabs that come to our supermarkets from tropical regions can be contaminated all year round and to a high percentage," warn the researchers in a message from the Max Planck Institute for Terrestrial Microbiology. It becomes problematic if they are eaten raw or only incompletely cooked.

Mechanism of spread of the bacteria is still unclear

In order to develop measures against the spread of Vibrio parahaemolyticus and other vibrions, the structure and the spreading strategy of the bacterial colonies must first be decoded, explains the study leader Ringgaard. It is already known that Vibrio parahaemolyticus forms colonies in the tidal zone of estuaries and that its complex life cycle is based on the respective conditions of this habitat. But how exactly this adaptation takes place and how the bacteria spread under these difficult conditions has so far remained largely unclear.

Different cell types of the bacterium

The research team therefore simulated the conditions of the tidal zone in the laboratory and carefully analyzed the life cycle and the movement mechanisms of Vibrio parahaemolyticus. Many bacteria use special cell types to adapt to the environmental conditions and this also applies to Vibrio parahaemolyticus. For example, the bacterium could form short swimmer cells with a single polar cell flagella that can move quickly in a liquid environment, or elongated swimmer cells that colonize solid surfaces as a colony in a slower, creeping movement

Special structure of the bacterial colonies

In their investigations, the researchers found that "the vibrio bacterial colonies of the tidal zone have a very specific stratification: while the middle of the colony consists of rather shorter cells, the longer swarm cells are found in the outer areas of the colony." When the colony is flooded with water, which takes place in the natural habitat, cells of this colony are released into the liquid environment, the research team continues.

"Adventurer" cells responsible for the spread

Examination of the released cells after a flood showed, however, that it was not the long swarm cells or the very short cells that set off. Instead, the researchers found an unexpected and new medium-length cell type. These "adventurer" cells were optimized for life in the water and had particularly good swimming properties.

Targeted search for nutrients

The researchers also found that after their release, the adventurer cells spread to their new liquid environment, targeting potential nutrient sources such as chitin. You move towards the nutrient sources. Chitin is contained in the exoskeleton of many marine animals and so the bacteria eventually reach the human food chain.

Significance for worldwide epidemiology

“Our experiments show that the colony always has a sub-population of adventurer cells ready to release these specialized cells immediately when flooded. Adventurer cells would be of central importance for the worldwide epidemiology of the disease - and thus also for measures to contain it, for example in industrial aquaculture, ”the study leader concluded. (fp)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Dipl. Geogr. Fabian Peters

Swell:

  • Max Planck Institute for Terrestrial Microbiology: Bacterial Pathogens from the Sea (published October 21, 2019), mpi-marburg.mpg.de
  • Carolina Freitas, Timo Glatter, Simon Ringgaard: The release of a distinct cell type from swarm colonies facilitates dissemination of Vibrio parahaemolyticus in the environment; in: The ISME Journal (published 10/17/2019), nature.com


Video: Gastrointestinal Infections (October 2022).