Immunochemical characterization of the O antigens of two Proteus strains, O8-related antigen of Proteus mirabilis 12 B-r and O2-related antigen of Proteus genomospecies 5/6 12 B-k, infecting a hospitalized patient in Poland

Abstract

A hospitalized 73-year-old woman was infected with a Proteus mirabilis strain, 12 B-r, isolated from the place of injection of a blood catheter. Another strain, 12 B-k, recognized as Proteus genomospecies 5 or 6, was isolated from the patient's faeces, which was an example of a nosocomial infection rather than an auto-infection. Serological investigation using ELISA and Western blotting showed that strain 12 B-k from faeces belonged to the Proteus O2 serogroup. Strain 12 B-r from the wound displayed cross-reactions with several Proteus O serogroups due to common epitopes on the core or O-specific parts of the lipopolysaccharide. Studies of the isolated 12 B-r O-specific polysaccharide by NMR spectroscopy revealed its close structural similarity to that of Proteus O8. The only difference in 12 B-r was the presence of an additional GlcNAc-linked phosphoethanolamine residue, which creates a putative epitope responsible for the cross-reactivity with Pt. mirabilis O16. The new O-antigen form could appear as a result of adaptation of the bacterium to a changing environment. On the basis of the data obtained, we suggest division of the O8 serogroup into two subgroups: O8a for strains of various Proteus species that have been previously classified into the O8 serogroup, and O8a,b for Pt. mirabilis 12 B-r, where 'a' is a common epitope and 'b' is a phosphoethanolamine-associated epitope. These findings further confirm serological and structural heterogeneity of O antigens of Proteus strains isolated lately from patients in Poland.

The Prevailing O Serogroups Among the Serologically Differentiated Clinical Proteus Spp. Strains in Poland

“…A total of the 580 S strains (possessing an O antigen in the LPS molecules) were serologically investigated to classify them into proper O serogroups in the genus Proteus. The results for 24 of these strains classi ed to O2, O8, O11, O77 -O82 serogroups, respectively, had been reported previously [13][14][15][16][17][18][19][20] .…”

“…Other frequent sources of isolation were connected with the respiratory tract (bronchoaspirates, sputum, and the pharyngonasal cavity), faeces, and vagina, while strains from other sources were isolated rarely. Moreover, the bacteria ( ve P. mirabilis strains) were also detected in faecal samples taken from only ve out of 181 healthy volunteers (2.8%) and in faecal samples from as many as six out of eight infected individuals (four P. mirabilis, one P. vulgaris, and one P. genomospecies 5/6 including four strains reported earlier [13,14,20]). Thus, it was shown that the 11 Proteus spp.…”

“…strains were collected in Łódź, Poland (Fig. 1) including the 24 clinical strains reported earlier [13][14][15][16][17][18][19][20]. What is worth noticing, no strains were collected from blood, although Proteus spp.…”

“…1) were kindly provided in 2006-2011 by four big medical laboratories in Łódź (Poland): in Barlicki Hospital, in Biegański Hospital, "Synevo", "Diagnostyka". Some strains were isolated from faeces of 189 volunteers using McConkey and Nogrady media plates and recognized as forming the urease-positive and lactose-negative colonies, as described [20]. All isolates were identi ed by the cultivation on the media proposed by Senior [21], modi ed as described [13], additional tests were applied for the strains recognized as P. genomospecies, as described [4,15] (Table 1).…”

“…clinical isolates from the Łódź region (central Poland) enabled us to study their serological differentiation. Up to date, serologically unique strains from the collection have formed six new serogroups O77-O82 [13][14][15][16][17][18] and two new subgroups in O8 and O11 serogroups [19,20]. In this work the serological variety of the whole collection of Proteus spp.…”