A new fimbrial antigen harbored by CAZ-5/SHV-4-producing Klebsiella pneumoniae strains involved in nosocomial infections.
We purified and characterized a new fimbria termed KPF-28 (Klebsiella pneumoniae fimbria with a fimbrin molecular mass of 28 kDa) involved in K. pneumoniae adherence to the human carcinoma cell line Caco-2. Electron microscopy of bacterial surface protein preparations and immunogold labeling of bacterial cells showed that KPF-28 was a long, thin, and flexible fimbria about 4 to 5 nm in diameter and 0.5 to 2 microm long. The N-terminal amino acid sequence of the KPF-28 major fimbrial subunit showed no homology with type 1 and type 3 pili of K. pneumoniae but showed 61.7% identity with residues 6 to 19 of the N-terminal amino acid sequence of PapA, the Pap major pilus subunit expressed by uropathogenic Escherichia coli strains. Total amino acid content determination showed that the KPF-28 major subunit composition was close to that of the GVVPQ fimbrial family major subunits expressed by pathogenic E. coli strains. The study of the prevalence of KPF-28 among K. pneumoniae strains involved in nosocomial infections revealed that KPF-28 was found in the great majority of the K. pneumoniae strains producing the CAZ-5/SHV-4 extended-spectrum beta-lactamase. As shown by curing and mating experiments, the R plasmid encoding the CAZ-5/SHV-4 enzyme was found to be involved in but not solely responsible for KPF-28 expression. Hybridization experiments using an oligonucleotide probe corresponding to the N-terminal part of the 28-kDa protein revealed that the structural gene encoding the KPF-28 major subunit was localized on this R plasmid. KPF-28 is a putative colonization factor of the human gut, since the ceftazidine-sensitive derivative strain CF914-1C no longer adhered and since the Fab fragments of antibodies raised against KPF-28 inhibited adhesion of K. pneumoniae CF914-1 to the Caco-2 cell line.
Di Martino
P
P
Laboratoire de Bactériologie, Facultés de Pharmacie et Médecine, Clermont-Ferrand, France.
Livrelli
V
V
Sirot
D
D
Joly
B
B
Darfeuille-Michaud
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D001483:Base Sequence; D018938:Caco-2 Cells; D003428:Cross Infection / Q000382:microbiology*; D010861:Fimbriae, Bacterial; D006801:Humans; D015151:Immunoblotting; D007711:Klebsiella pneumoniae / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010957:Plasmids; D011817:Rabbits
D001426:Bacterial Proteins