Sludge Watch ==> Ecoli and other pathogenic bacteria can swim upstream

[Maureen Reilly]

Quote from the study:

"We think that upstream swimming of bacteria may be relevant to the 
transport of E. coli in the urinary tract," said Kaiser. "It might also 
explain the high rates of infection in catheterized patients and the 
incidence of microbial contamination at protected wellheads. "












Swimming 'to The Left' Gets Bacteria Upstream, And May Promote Infection
17 Feb 2007

Yale engineers who study both flow hydrodynamics and how bacteria propel 
themselves report that one reason for the high incidence of infections 
associated with catheters in hospital patients may be that some pathogenic 
bacteria swim "to the left," in a study published in Physical Review 
Letters.

"Escherichia coli (E. coli) and some other pathogenic bacteria with flagella 
interact with the flow of liquid when they are near a surface," said H 
Kaiser, assistant professor of electrical engineering at Yale and the 
study's senior author, who has collaborated with a diverse team of 
scientists for this study.

"Each cell normally has two to six flagella that can rotate together as a 
bundle and act as a propeller to drive the cell forward. Away from any 
boundaries, the cells swim in a straight line, but near a surface, opposing 
forces of flow and bacterial forward motion cause the bacteria to 
continuously swim to one side - to the left." The study determined that 
swimming "to the left" is a hydrodynamic process that is fundamentally 
related to the way the cells propel themselves in this manner.

Köser and his colleagues show that this phenomenon allows flagellated 
bacteria, such as E. coli, to find crevices or imperfections on the surface, 
get trapped, and swim upstream. This allows the bacteria to eventually 
locate large reservoirs with richer sources of food and better conditions 
for multiplying.

"We think that upstream swimming of bacteria may be relevant to the 
transport of E. coli in the urinary tract," said Köser. "It might also 
explain the high rates of infection in catheterized patients and the 
incidence of microbial contamination at protected wellheads. To our 
knowledge, this is the first time that a natural propensity to swim upstream 
has been discovered and described in bacteria."

To study the hydrodynamics of these bacteria in a flow environment, Köser's 
team constructed microfluidic devices using soft lithography. Inside the 
devices they set up various flow patterns to observe the bacteria in 
channels that were only 150 or 300 microns wide and between 50 and 450 
microns deep. They were able to observe how the bacteria moved at a wide 
range of flow rates - between 0.05 and 20 microliters per minute.

Co-authors on the paper are Jane Hill in Yale's Environmental Engineering 
Program, Jonathan L. McMurry, then in Yale's Molecular Biophysics and 
Biochemistry Department and Ozge Kalkanci at Bogazici University, Istanbul, 
Turkey. The research was mainly supported through funds from Yale 
University.

###

Citation: Physical Review Letters: early online February 6, 2007
DOI: 10.1103/PhysRevLett.98.068101

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Article URL: http://www.medicalnewstoday.com/medicalnews.php?newsid=63050