title: Environmental growth conditions influence the ability of Escherichia coli K1 to invade brain microvascular endothelial cells and confer serum resistance.
abstract: A major limitation to advances in prevention and therapy of neonatal meningitis is our incomplete understanding of the pathogenesis of this disease. In an effort to understand the pathogenesis of meningitis due to Escherichia coli K1, we examined whether environmental growth conditions similar to those that the bacteria might be exposed to in the blood could influence the ability of E. coli K1 to invade brain microvascular endothelial cells (BMEC) in vitro and to cross the blood-brain barrier in vivo. We found that the following bacterial growth conditions enhanced E. coli K1 invasion of BMEC 3- to 10-fold: microaerophilic growth, media buffered at pH 6.5, and media supplemented with 50% newborn bovine serum (NBS), magnesium, or iron. Growth conditions that significantly repressed invasion (i.e., 2- to 250-fold) included iron chelation, a pH of 8.5, and high osmolarity. More importantly, E. coli K1 traversal of the blood-brain barrier was significantly greater for the growth condition enhancing BMEC invasion (50% NBS) than for the condition repressing invasion (osmolarity) in newborn rats with experimental hematogenous meningitis. Of interest, bacterial growth conditions that enhanced or repressed invasion also elicited similar serum resistance phenotype patterns. This is the first demonstration that bacterial ability to enter the central nervous system can be affected by environmental growth conditions.
authors.affiliation: Division of Infectious Diseases, Childrens Hospital Los Angeles, Los Angeles, California 90027, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Badger
authors.forename: K S
authors.initials: KS
authors.lastname: Kim
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis; D001769:Blood; D002490:Central Nervous System / Q000382:microbiology; D002560:Cerebrovascular Circulation; D003470:Culture Media; D004730:Endothelium, Vascular / Q000382:microbiology*; D004777:Environment; D004926:Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000209:etiology*; D006863:Hydrogen-Ion Concentration; D016920:Meningitis, Bacterial / Q000209:etiology*; D008833:Microcirculation / Q000382:microbiology; D010100:Oxygen; D051381:Rats
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; C078167:OMPA outer membrane proteins; D010100:Oxygen