Antiserum against Raoultella terrigena ATCC 33257 identifies a large number of Raoultella and Klebsiella clinical isolates as serotype O12

Abstract

Raoultella terrigena ATCC 33257, recently reclassified from the genus Klebsiella, is a drinking water isolate and belongs to a large group of non-typeable Klebsiella and Raoultella strains. Using an O-antiserum against a capsule-deficient mutant of this strain, we could show a high prevalence (10.5%) of the R. terrigena O-serotype among non-typeable, clinical Klebsiella and Raoultella isolates. We observed a strong serological cross-reaction with the K. pneumoniae O12 reference strain, indicating that a large percentage of these non-typeable strains may belong to the O12 serotype, although these are currently not detectable by the K. pneumoniae O12 reference antiserum in use. Therefore, we analyzed the O-polysaccharide (O-PS) structure and genetic organization of the wb gene cluster of R. terrigena ATCC 33257, and both confirmed a close relation of R. terrigena and K. pneumoniae O12. The two strains possess an identical O-PS, lipopolysaccharide core structure, and genetic organization of the wb gene cluster. Heterologous expression of the R. terrigena wb gene cluster in Escherichia coli K-12 resulted in the WecA-dependent synthesis of an O-PS reactive with the K. pneumoniae O12 antiserum. The serological data presented here suggest a higher prevalence of the O12-serotype among Klebsiella and Raoultella isolates than generally assumed.

Bacteriophage-mediated Glucosylation Can Modify Lipopolysaccharide O-Antigens Synthesized by an ATP-binding Cassette (ABC) Transporter-dependent Assembly Mechanism

“…The R. terrigena O-antigen shares the same repeating unit (and serological cross-reactivity) with the K. pneumoniae O12 antigen, where the same repeat unit polysaccharide is terminated with a single ␤-Kdo residue at the nonreducing terminus (37). Signals consistent with this terminator were reported in the NMR spectrum of R. terrigena O-antigen (31). The sequence data are consistent with WbbB partici- pating in both chain extension and chain termination, but this remains to be confirmed biochemically, and the precise activities giving rise to the O-antigen backbone are not central to the current study.…”

“…4, bottom panel, and Table 1), as well as the 1 H, 13 C heteronuclear single-quantum coherence spectrum of the O-antigen expressed in CWG1218 (⌬wzx-wbbK ⌬gtrA) and comparison with data reported previously (31), confirmed that it possesses a disaccharide repeat unit structurally identical to that of the R. terrigena ATCC 33257 and K. pneumoniae O12 O-antigen (Fig. 1).…”

“…3). This anomaly was noted previously in a different E. coli background, but the molecular basis was not examined (31).…”

“…For O-antigen immunoblot analysis, LPS was transferred to nitrocellulose membranes (Protran; PerkinElmer Life Sciences) and probed with rabbit antiserum generated against Klebsiella pneumoniae O12 formalin-fixed whole cells. The K. pneumoniae O12 antigen is structurally and serologically identical to the O-antigen in R. terrigena ATCC 33257 (31). Goat anti-rabbit secondary antibody conjugated to alkaline phosphatase (Cedarlane Laboratories) was used, and the immunoblot was developed with 5-bromo-4-chloro-3-indoyl phosphate and nitroblue tetrazolium (Roche Applied Science).…”

A new emerging oral infection: Raoultella planticola in a boy with haematological malignancy

“…and RP has been investigated finding that both, Klebsiella pneumoniae and RP, have type 1 fimbriae and mannosesensitive haemagglutination; furthermore Klebsiella spp. have the ability to resist the bactericidal effects of human serum, a feature that is shared by RP (Mertens et al 2010).…”