The O-chain polysaccharide of the lipopolysaccharide (LPS) of a previously nonclassified strain of Proteus mirabilis termed G1 was studied by sugar analysis and The structure of the O-polysaccharide of P. mirabilis G1 is similar, but not identical, to that of P. mirabilis S1959 and OXK belonging to serogroup O3. Immunochemical studies with P. mirabilis G1 and S1959 anti-(O-polysaccharide) sera revealed close LPS-based serological relatedness of P. mirabilis G1 and S1959, and therefore it was suggested to classify P. mirabilis G1 in serogroup O3 as a subgroup. P. mirabilis G1 and S1959 anti-(O-polysaccharide) sera also cross-reacted with LPS of P. mirabilis strains from two other serogroups containing D-GalA6(L-Lys) in the O-polysaccharide or in the core region.

The genus Proteus belongs to the Enterobacteriaceae family, where it is placed in the tribe Proteeae, together with the genera Morganella and Providencia. Currently, the genus Proteus consists of five species: P. mirabilis, P. vulgaris, P. penneri, P. hauseri and P. myxofaciens, as well as three unnamed Proteus genomospecies. The most defining characteristic of Proteus bacteria is a swarming phenomenon, a multicellular differentiation process of short rods to elongated swarmer cells. It allows population of bacteria to migrate on solid surface. Proteus bacteria inhabit the environment and are also present in the intestines of humans and animals. These microorganisms under favorable conditions cause a number of infections including urinary tract infections (UTIs), wound infections, meningitis in neonates or infants and rheumatoid arthritis. Therefore, Proteus is known as a bacterial opportunistic pathogen. It causes complicated UTIs with a higher frequency, compared to other uropathogens. Proteus infections are accompanied by a formation of urinary stones, containing struvite and carbonate apatite. The virulence of Proteus rods has been related to several factors including fimbriae, flagella, enzymes (urease - hydrolyzing urea to CO2 and NH3, proteases degrading antibodies, tissue matrix proteins and proteins of the complement system), iron acqusition systems and toxins: hemolysins, Proteus toxin agglutinin (Pta), as well as an endotoxin - lipopolysaccharide (LPS). Proteus rods form biofilm, particularly on the surface of urinary catheters, which can lead to serious consequences for patients. In this review we present factors involved in the regulation of swarming phenomenon, discuss the role of particular pathogenic features of Proteus spp., and characterize biofilm formation by these bacteria.

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Nests of secondary-cavity breeding birds are structures constructed to lay and incubate eggs and raise nestlings to fledging. These nests are characterized by relatively stable conditions, which makes them a suitable habitat for various microorganisms. It has been suggested that bacteria inhabiting nests and nestling skin may affect nestlings both positively and negatively. In this study, nests of Great Tits Parus major were replaced with artificial nests on the fifth day of the nestling phase in two different study sites to create two categories of nests: (i) natural and (ii) artificial with a reduced bacterial load. Four days later, bacterial samples were collected from the nestling skin and from the edge of the nest to assess skin and nest bacterial loads, expressed as colony forming units (CFUs). It was predicted that (i) the previous season occupancy of nest boxes would influence bacterial loads, (ii) the experimental treatment would reduce nest and skin bacterial loads, and (iii) that nest and skin bacterial loads would affect the condition of the nestlings, assessed as the hemoglobin concentration in blood when nestlings were 14 days old. Occupancy in the previous season did not affect the bacterial load. The skin bacterial load was significantly lower in artificial nests, although the nest bacterial load did not differ between natural and artificial nests. Nestlings from artificial nests had higher hemoglobin, and hemoglobin concentration was negatively associated with the nest but not the skin bacterial load. Our results suggest that the bacterial load in nests may negatively affect the physiological condition of avian hosts. Keywords Nest bacterial load • Skin bacterial load • Nest replacement • Great tit • Hemoglobin • Nestling condition Zusammenfassung Nestaustauschexperimente liefern Hinweise auf einen Einfluss der Bakterienbelastung der Nester auf die physiologische Kondition der Nestlinge höhlenbrütender Kohlmeisen (Parus major) Die Nester sekundärer Höhlenbrüter sind Gebilde, welche für Eiablage, Bebrütung und die Aufzucht der Nestlinge bis zum Flüggewerden errichtet werden. Diese Nester zeichnen sich durch relative stabile Bedingungen aus, was sie zu einem geeigneten Lebensraum für diverse Mikroorganismen macht. Es wird vermutet, dass die Bakterien, welche in den Nestern und auf der Haut der Nestlinge leben, die Nestlinge sowohl positiv als auch negativ beeinflussen können. In dieser Studie ersetzten wir in zwei verschiedenen Untersuchungsgebieten Nester von Kohlmeisen Parus major am fünften Tag der Nestlingsphase durch Kunstnester und schufen dadurch zwei Nestkategorien: (i) Naturnester und (ii) Kunstnester mit verringerter Bakterienbelastung. Vier Tage später nahmen wir Bakterienproben von der Haut der Nestlinge sowie vom Communicated by S. Bouwhuis.