Pseudomonas Article

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Abstract :

LACTOFERRIN BLOCKS BACTERIAL BIOFILM FORMATION BY SEQUESTERING FREE IRON

Subinhibitory concentrations of lactoferrin prevents Pseudomonas

aeruginosa from forming biofilms by sequestering free iron, which in

turn increases bacterial motility, according to a report in the May 30th

issue of Nature.

Reuters Health Information 2002

medscape.com/viewarticle/434388?srcmp=id-053102

Full Article :

Lactoferrin Blocks Bacterial Biofilm Formation by Sequestering Free Iron

NEW YORK (Reuters Health) May 30 - Subinhibitory concentrations of

lactoferrin prevents Pseudomonas aeruginosa from forming biofilms by

sequestering free iron, which in turn increases bacterial motility, according

to a report in the May 30th issue of Nature. Dr. Pradeep K. Singh, of the

University of Iowa College of Medicine in Iowa City, and associates

conjectured that iron-unsaturated lactoferrin, found abundantly in tears,

airway secretions, and breast milk, may comprise part of the innate immune

system present on mucosal surfaces. In the absence of lactoferrin, the

researchers found that P. aeruginosa began to form microcolonies after 24

hours in flow cell chambers. " By day 7, towering pillar and mushroom-shaped

biofilms had developed, " the authors write. In contrast, iron-unsaturated

lactoferrin, but not the iron-saturated protein, prevented biofilm formation

even after prolonged incubation. However, the subinhibitory concentrations of

lactoferrin did not hamper the growth of free-swimming bacteria. The

researchers described three types of bacteria according to behavior:

squatters, which remain stationary after cell division; ramblers, which move

across the surface of the flow cell away from the division site; and flyers,

which are swept away by the flow of the culture medium. In the absence of

lactoferrin, most cells were squatters, and ramblers were rare. Conversely,

the presence of iron-unsaturated lactoferrin resulted in a predominance of

ramblers, with fewer squatters, the investigators note. The researchers also

evaluated wild-type P. aeruginosa that exhibits a " twitching " type of surface

locomotion mediated by type 4 pili. Mutant bacteria unable to twitch were

unaffected by lactoferrin in their biofilm formation ability. The bacteria's

response to the lack of iron makes sense, Dr. Singh said in an interview with

Reuters Health. " Why settle in a nutrient-poor environment? " Without iron,

the bacteria are " stimulated to move around and find a better place, " he

added. Dr. Singh and his colleagues found that lactoferrin did not reverse

the growth of existing biofilms, indicating the protein can only be used to

prevent biofilms from forming. Researchers may one day determine how to use

lactoferrin to disarm biofilms in the body, Dr. Singh said, but may never

discover how to apply this technique to the lungs of cystic fibrosis

patients. Patients would have to be given large quantities of the protein, he

explained, an amount that could be difficult to produce and might ultimately

be toxic. Lactoferrin holds more promise as a coating for medical devices,

according to the Iowa researcher. As foreign materials with no innate

defenses against bacteria, implantable devices are at risk of developing

biofilms. In addition, biofilms can form on neighboring tissues that have

been disturbed by the foreign object. Nature 2002;417:552-555.

Becki

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