Classification of Proteus penneri lipopolysaccharides into core region serotypes

Abstract

The frequency of P. penneri isolation from hospital patients, mostly from urine and wounds, keeps on growing, and numerous isolates are multi-drug resistant. P. penneri rods produce lipopolysaccharide (LPS), which may lead to the septic shock. Until now, O-specific polysaccharide has been the best structurally and serologically characterized region of P. penneri LPS. It is worth having an insight into the serological specificity of both poly- and oligosaccharide parts of P. penneri LPS. The P. penneri core region is less structurally diverse than OPS, but still, among other enterobacterial LPS core regions, it is characterized by structural variability. In the present study, the serological reactivity of 25 P. penneri LPS core regions was analyzed by ELISA, passive immunohemolysis and Western blot technique using five polyclonal P. penneri antisera after or without their adsorption with the respective LPSs. The results allowed the assignment of the tested strains to five new core serotypes, which together with published serological studies led to the creation of the first serotyping scheme based on LPS core reactivities of 35 P. penneri and three P. mirabilis strains. Together with the O types scheme, it will facilitate assigning Proteus LPSs of clinical isolates into appropriate O and R serotypes.

The New Structure of Core Oligosaccharide Presented by Proteus penneri 40A and 41 Lipopolysaccharides

“…P. penneri 103 was classified into serotype group no. 10 together with P. penneri 75 LPS, recognized by anti-core-specific antibodies present in P. penneri 103 antiserum [ 10 ]. A similar situation also occurs in the case of two core oligosaccharide serotypes: R1 (α- d -Glc p -(1→4)-α- d -Gal p NAc-(1→2)-α- dd -Hep p -(1→6)-α- d -Glc p NGly) presented by P. penneri 7, 14 LPSs and R2 presented by P. penneri 8 LPS (α- d -Gal p NAc-(1→2)-α- dd -Hep p -(1→6)-α- d -Glc p NGly) differing in the lack of terminal residue [ 4 , 14 ].…”

“…The serological studies performed by use of P. penneri 7 core-specific antiserum and P. penneri 7, 8, 14 and 15 LPSs proved a crucial role of the terminal residue from the outer core region in its serospecificity [ 8 ]. As a result, P. penneri 8 LPS and P. penneri 7, 14 and 15 LPSs were classified into two different core oligosaccharide serotypes [ 10 ]. The 6- O -acetylation of the Gal p N residue is also unique for the Proteus spp.…”

“…The results presented in this work will allow P. penneri 40A and 41 LPSs to be classified into a new core oligosaccharide serotype group extending the core oligosaccharide serotypes scheme [ 10 ]. It is another example of two P. penneri LPSs of one core serotype but presenting two O serotypes: P. penneri 40A (O64a,b,d) and P. penneri 41 (O62)—the first representative of this O serogroup in the core types classification scheme.…”

“…Finding a new structure and serotype of the P. penneri LPS core region confirmed the huge structural heterogeneity of P. penneri LPSs, a unique phenomenon among other Enterobacteriaceae . Extension of the core serotype scheme with other representatives may be helpful in the identification of the most common R and O serotypes needed for the selection of vaccine antigens to obtain cross-reactive and cross-protective antibodies [ 10 ].…”

“…This observation encouraged the examination of different P. penneri LPSs, in search of antigen groups with identical or similar serological activities of their core oligosaccharides, which would complete the Proteus classification scheme with the data on the core region serotypes. To date, 11 groups of LPS presenting one core serotype have been classified [ 10 ]. In this paper, the results of serological studies and structural analysis are presented to show another type among P. penneri LPSs with a common sero- and chemotype of their core oligosaccharides.…”