title: Cytotoxic effects of Klebsiella oxytoca strains isolated from patients with antibiotic-associated hemorrhagic colitis or other diseases caused by infections and from healthy subjects.
abstract: Antibiotic-associated hemorrhagic colitis (AAHC) is associated with Klebsiella oxytoca. This study analyzed whether cytotoxic properties are linked to specific subtypes of K. oxytoca. Klebsiella isolates from stools of AAHC patients, healthy carriers, and diarrhea patients as well as from infections of other organs were investigated. Cytotoxic effects on human epithelial cells were limited to the species K. oxytoca and were not detectable for any other Klebsiella species. Isolates from AAHC patients and from stools showed the highest proportion of cytotoxic strains. Urinary or respiratory tract isolates exhibited no cytotoxicity. Macrorestriction profiling of strains revealed no genetic relationships of AAHC isolates or the cytotoxic phenotype but identified that different K. oxytoca strains with different cytotoxic behaviors may be prevalent in the same AAHC patient. Under laboratory conditions, cytotoxicity was maximally effective after exponential bacterial growth and then declined despite the continued viability of K. oxytoca cells in culture. Given its capacity to induce AAHC and that a high proportion of stool isolates tested cytotoxin positive, we argue that K. oxytoca should be considered an opportunistic pathogen if detected in stools. The ability to induce disease after antibiotic treatment most likely represents an overgrowth of the toxin-producing bacterium due to an alteration of the normal colonic microflora.
authors.affiliation: Institute of Molecular Biosciences, University of Graz, Graz, Austria.
authors.forename: Martina M
authors.initials: MM
authors.lastname: Joainig
authors.forename: Gregor
authors.initials: G
authors.lastname: Gorkiewicz
authors.forename: Eva
authors.initials: E
authors.lastname: Leitner
authors.forename: Paul
authors.initials: P
authors.lastname: Weberhofer
authors.forename: Ines
authors.initials: I
authors.lastname: Zollner-Schwetz
authors.forename: Irmgard
authors.initials: I
authors.lastname: Lippe
authors.forename: Gebhard
authors.initials: G
authors.lastname: Feierl
authors.forename: Robert
authors.initials: R
authors.lastname: Krause
authors.forename: Thomas
authors.initials: T
authors.lastname: Hinterleitner
authors.forename: Ellen L
authors.initials: EL
authors.lastname: Zechner
authors.forename: Christoph
authors.initials: C
authors.lastname: Högenauer
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001427:Bacterial Toxins / Q000096:biosynthesis*; D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000382:microbiology*; D002460:Cell Line; D002470:Cell Survival; D003092:Colitis / Q000382:microbiology*; D003603:Cytotoxins / Q000096:biosynthesis*; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004847:Epithelial Cells / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology*; D041121:Klebsiella oxytoca / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D003603:Cytotoxins; D004269:DNA, Bacterial