Basic Info

Serotype prediction based on their surface antigens, such as O, H, and K antigens.

More Details

The serotype represents the genetic markers displayed by proteins in blood plasma. Due to the genetic polymorphism of some serum proteins, phenotypic differences arise among individuals. Therefore, serotyping has become an important classification method, especially for many foodborne microorganisms such as Salmonella and Listeria monocytogenes. This method is also widely used in epidemiological investigations. By determining the serotype of bacteria, we can provide a solid basis for antimicrobial therapy. Specifically, through in-depth analysis of the characteristics of bacterial somatic cells, such as the O antigen, cell surface proteins, H antigen, and K antigen, we can accurately classify bacteria based on their serotypes.

What's New

New therapies that target the bacterial capsular polysaccharide show promise as effective tools to curb the high mortality rates associated with extensively resistant Acinetobacter Baumannii (A. baumannii). Most genes responsible for polysaccharide capsule biosynthesis are clustered together in the chromosome between fkpA and lldP genes. However, many different sets of genes have been found at this ‘K locus’ (KL). To date, 241 fully annotated KL sequences have been identified, with KL2 being the most common followed by the related KL3 and KL22. A second locus with variable gene content involved in the production of a surface polysaccharide has been shown to be responsible for synthesis of the outer-core (OC) component of the lipooligosaccharide. The OC locus (OCL) is located in the chromosome between the aspS and ilvE genes. Each distinct gene cluster found between the flanking genes is assigned a unique number identifying the locus type (OCL1, OCL2, etc.), and to date, 14 different gene clusters (OCL1–OCL12 and OCL15 and OCL16 have been reported. 

Kaptive is a system for surface polysaccharide typing from Acinetobacter Baumannii genome sequences.

Additional Information

Related links:

https://github.com/klebgenomics/Kaptive

Literature

Cahill SM, Hall RM, Kenyon JJ. An update to the database for Acinetobacter baumannii capsular polysaccharide locus typing extends the extensive and diverse repertoire of genes found at and outside the K locus. Microb Genom. 2022;8(10):mgen000878. doi:10.1099/mgen.0.000878

Wyres KL, Cahill SM, Holt KE, Hall RM, Kenyon JJ. Identification of Acinetobacter baumannii loci for capsular polysaccharide (KL) and lipooligosaccharide outer core (OCL) synthesis in genome assemblies using curated reference databases compatible with Kaptive. Microb Genom. 2020;6(3):e000339. doi:10.1099/mgen.0.000339

Lam MMC, Wick RR, Judd LM, Holt KE, Wyres KL. Kaptive 2.0: updated capsule and lipopolysaccharide locus typing for the Klebsiella pneumoniae species complex. Microb Genom. 2022;8(3):000800. doi:10.1099/mgen.0.000800