title: Naturally-occurring, osmo-remedial variants of Escherichia coli.
abstract: Two clones of Escherichia coli O27:K1:H31 and O2:H7, isolated from patients with urinary tract infection or bacteraemia, failed to grow in a synthetic minimal medium (MM) of low osmolality. They were considered to be osmo-remedial because they grew well when sufficient amounts of NaCl, mannitol or sucrose were added to raise the osmolality of the medium to > 300 mOsm/kg. The defect could also be corrected by nicotinamide or its precursors quinolinic and aspartic acids. Each clone had a unique DNA restriction enzyme profile, fimbriae and antibiotic susceptibility patterns. The osmo-remedial variants were unstable and underwent phenotypic modulation to form mixtures with osmo-tolerant forms when grown in MM. They tended to form satellites of small colonies around large colonies of osmo-tolerant cells on MM agar plates. The penicillin method of Davis was used to separate the two forms. Nicotinamide induced the expression of ompF when the osmo-remedial strains were grown under conditions of low osmolality. It is possible that the variants are defective in the synthesis of membrane-derived oligosaccharides or outer-membrane proteins, but this has yet to be determined.
authors.affiliation: Department of Internal Medicine, Ohio State University, Columbus 43210.
authors.forename: C M
authors.initials: CM
authors.lastname: Kunin
authors.forename: H H
authors.initials: HH
authors.lastname: Tong
authors.forename: W E
authors.initials: WE
authors.lastname: Maher
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D016470:Bacteremia / Q000382:microbiology; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000382:microbiology; D005260:Female; D006801:Humans; D008353:Mannitol / Q000494:pharmacology; D009536:Niacinamide / Q000494:pharmacology; D009994:Osmolar Concentration; D010405:Penicillinase / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D014552:Urinary Tract Infections / Q000382:microbiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D004269:DNA, Bacterial; D009536:Niacinamide; D008353:Mannitol; D012965:Sodium Chloride; D000667:Ampicillin; D010405:Penicillinase