Characterization of Klebsiella terrigena strains from humans: haemagglutinins, serum resistance, siderophore synthesis, and serotypes

Klebsiella terrigena is very rarely isolated from humans; as yet, its clini cal significance is uncertain. The aim of the present study was to evaluate whether this species is able to express putative virulence factors. A tota l of 72 faecal (n = 50) and clinical (n = 22) K. terrigena isolates was inv estigated and compared with faecal and clinical strains of K. pneumoniae. M annose-sensitive haemagglutination (MSHA) was observed less often in K. ter rigena (64-74 %) than in K. pneumoniae strains. In contrast, the incidence of mannose-resistant haemagglutinin indicative of type 3 pili (MR/K-HA) (77 -94 %), serum resistance properties (10-23 %), and production of enterobact in (100 %) was similar in both species. None of the K. terrigena isolates w ere able to synthesize aerobactin; however, the frequency of aerobactin syn thesis in K. pneumoniae was also only 5%. Serotyping showed capsular types KS and K70 to be predominant. The virulence-associated serotype K2 was comm on in both K. terrigena and K. pneumoniae isolates. Taken together, the pre sent results suggest that K. terrigena and K. pneumoniae are indistinguisha ble with respect to the expression of virulence factors.