Urinary Tract Infection
Anthony R. Mundy, John M. Fitzpatrick, David E. Neal, Nicholas J. R. George in The Scientific Basis of Urology, 2010
The antigenic structure of the bacterial surface is classically described in terms of three classes of antigens. O-Antigens represent the polysaccharide side chains of the lipopolysaccharide structure found in all gram-negative bacteria. The polysaccharide is anchored to the outer membrane by lipid A (Fig. 18), the agent thought to be responsible for endotoxic shock, as described below. O-antigens are heat stable and classically certain serogroups (01, 02, 04, 06, 07, 016, 018, and 075) responsible for urinary infections, such strains being responsible for up to 80% of cases of pyelonephritis. Modern theory suggests that the O-antigen is not itself specifically responsible for pathogenicity; rather, the identified serogroups represent clones of organisms with a selection or panel of various virulence properties that enable successful colonization of the urinary tract. Other serogroups and hence other combinations of virulence factors may enable successful colonization of other areas such as the gastrointestinal tract. K capsular antigen is partially heat stable and may, on occasion, partially obscure the O-antigen (Fig. 18). K capsular polysaccharide antigen has been strongly associated with pyelonephritis for many years, both in adults (71) and in children (72). Some 70% of strains from children with pyelonephritis were associated with K1, K2, K3, K12, and K13 antigens, of which K1 is acknowledged to be the most frequently associated strain with pyelonephritic disease. Interestingly, K1 strains have also been associated with 80% of E. coli strains causing neonatal meningitis (72).
Cronobacter: An Opportunistic Pathogen
Dongyou Liu in Handbook of Foodborne Diseases, 2018
Another method of species identification is based on detection of specific virulence genes by PCR and microarrays (16,17). Sequence type ST4 has been recently reported in C. sakazakii isolates that cause severe neonatal infections. The O-antigens present in Cronobacter species are responsible for the serological activity and form the basis for another method of classification of this genus (18–21). The lipopolysaccharide present on the surface of gram-negative bacteria contains carbohydrate antigens linked via O-bonds. Using a polymerase chain reaction-restriction fragment length polymorphism approach, two O-antigen serotypes (i.e., O:1 and O:2) are identified within C. sakazakii, and at least 15 serotypes are found among other Cronobacter species.
An Outbreak of Nontyphoid Salmonellosis in the Workplace
Meera Chand, John Holton in Case Studies in Infection Control, 2018
Salmonella is serotyped according to the O (somatic) antigens, Vi (capsular) antigens and H (flagellar) antigens (Figure 21.2). The Vi antigen is used to identify S. Typhi strains. Antigenic variation occurs on the O antigen. 99% of Salmonella species can be genus identified, using agglutination reactions of the O antigen, into groups AB, B, C, D and E. These groupings are not able to distinguish whether the organism is able to cause enteric fever. An example of this is that S. Enteritidis and S. Typhi are both group D; however S. Enteritidis causes NTS and S. Typhi causes enteric Typhoid fever.
Classification of Parabacteroides distasonis and other Bacteroidetes using O- antigen virulence gene: RfbA-Typing and hypothesis for pathogenic vs. probiotic strain differentiation
Published in Gut Microbes, 2022
Nicholas C. Bank, Vaidhvi Singh, Alex Rodriguez-Palacios
Extrapolating from prior research on E. coli and Salmonella,18–20 strain dependent mechanisms linked to bacterial surface markers, such as the O-antigen, could be used to help guide research and help propose studies to determine the causes that lead to the varied effects observed for Pdis on human and animal health. The O-antigen is a key virulence molecule of lipopolysaccharides (LPS) constitutively expressed on the cell wall surface of gram-negative bacteria. Lipopolysaccharide is a well understood virulence factor for gram-negative bacteria, consisting of lipid A, an oligosaccharide, and the O-antigen polysaccharide. The O-antigen is the immunogenic component of LPS, and as such can influence the host–bacterium relationship in several ways; potential mechanisms include resisting host complement and phagocytic engulfment, molecular mimicry, and colonization ability.21 Additionally, variation in the amount/type of monosaccharides in O-antigens provide major LPS structural diversity21 and virulence potential across bacteria (e.g. E. coli O157).
Phenotypic whole-cell screening identifies a protective carbohydrate epitope on Klebsiella pneumoniae
Published in mAbs, 2022
Sophia K. Berry, Steven Rust, Carolina Caceres, Lorraine Irving, Josefin Bartholdson Scott, David E. Tabor, Gordon Dougan, Graham Christie, Paul Warrener, Ralph Minter, Andrew J. Grant
Several sub-serotypes exist within the O1 and O2 serotypes (Figure S4). Of marked importance are sub-serotypes that harbor the gmlABC locus, which encodes the conversion of D-galactan-I to D-galactan-III,21 and which has been shown to be widely distributed among ST258 isolates,22 leading to the proposal of D-galactan-III as an attractive therapeutic target.22,23 To investigate the potential scope of use of B39, we investigated whether B39 could bind to clinically relevant sub-serotypes within the O1 and O2 serotypes, namely O1 gmlABC− (O1−), O1 gmlABC+ (O1+), O2 gmlABC− (O2−), and O2 gmlABC+ (O2+). The O-antigen structures of these serotypes are shown in Figure 6a.
Progress towards the development of Klebsiella vaccines
Published in Expert Review of Vaccines, 2019
Myeongjin Choi, Sharon M Tennant, Raphael Simon, Alan S Cross
Historically 12 KP O antigen serogroups were described, but it was later found that O6, O8, O9, and O11 were identical to other previously described bacteria and were relocated to the genus Enterobacteriaceae [21]. Trautmann et al. determined that over 80% of 378 clinical KP isolates from Germany belonged to one of four serogroups (O1, O2, O3, and O5) [22]. This finding was corroborated by others [23,24] and Follador et al [18]. who performed whole genome sequencing on a global collection of more than 500 human and environmental isolates. This study included strains from Australia, Indonesia, Laos, Nepal, Singapore, UK, USA, and Vietnam; 67 strains were isolated from blood, 47 strains were from urine and 20 strains were from sputum [18]. LPS O antigens are composed of mannans in O3 and O5 strains and galactans in O1 and O2 strains. Among galactans, D-gal I is capped by the D-gal II polymer in O1 strains, while O2 strains have D-gal I only [25,26]. Recently, the D-gal III variant of D-gal has been observed as part of the LPS of O1 and O2 of some strains; D-gal III is a branched polysaccharide product resulting from the conversion of the D-gal I disaccharide by the gmlABC operon [27].
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