PCR characterization and typing of Klebsiella pneumoniae using capsular type-specific, variable number tandem repeat and virulence gene targets.

A multiplex PCR is described which detects capsular types K1, K2, K5, K54 and K57, which are those most associated with invasive disease or pathogenicity, a further capsular type (K20), two putative virulence factors (rmpA and wcaG) and the 16S-23S internal transcribed spacer unit of Klebsiella pneumoniae, facilitating identification of this organism. wcaG encodes capsular fucose production and was associated with capsular types K1 and K54, but was also found in strains of other capsular types; 18 of the 543 isolates screened were PCR-positive for this gene. An eight-locus variable number tandem repeat (VNTR) scheme was designed, which provided discrimination at a level similar to that afforded by PFGE among a panel of 36 isolates representing 29 PFGE types. All isolates tested of the virulent K1 clone of CC23, associated with pyogenic liver abscesses, shared the same VNTR profile, which may be helpful in identifying this clone; such isolates were also PCR-positive for allS. These methods provide a rapid means of characterizing and typing isolates of this important agent of community-acquired and nosocomial infection.