Expression of putative virulence factors by clinical isolates of Klebsiella planticola

A total of 92 clinical isolates of Klebsiella planticola from man was examined with respect to the production of haemagglutinins and siderophores, serum resistance and distribution of capsular types. For comparison, a group of 207 clinical isolates of K. pneumoniae was also studied. The percentages of K. planticola strains able to express mannose-sensitive haemagglutination, indicating type 1 fimbriae (83%) and mannose-resistant and Klebsiella-like agglutination, indicating type 3 fimbriae (69%), as well as to produce the siderophores enterobactin (100%) and aerobactin (2.2%) were almost identical to those of the K. pneumoniae strains. Similarly, the proportion of serum-resistant strains (30%) was comparable to that of K. pneumoniae (25%). The capsule types most often detected in K. planticola were K14 (13%), K2 (9%) and K70 (9%). The incidence of K2, which is the predominant capsular type in K. pneumoniae, was similar in both species. These findings show that K. planticola, which is being detected with increasing frequency in clinical specimens from man, has the ability to express similar putative virulence factors to K. pneumoniae, suggesting that they may have similar pathogenicity.