Nonserotypable

Nonserotypable refers to microorganisms, particularly bacteria, that lack distinct surface antigens which can be reliably differentiated by specific antibodies. Serotyping is a method used to classify bacteria based on these surface antigens, known as serotypes. These serotypes are often identified using agglutination tests with specific antisera. For some bacteria, however, the antigens present on their surface are not sufficiently variable or are not recognized by the commonly available antisera used for serotyping.

This lack of serotypable characteristics means that these strains cannot be easily classified into distinct serotypes using standard serological methods. Consequently, they are termed nonserotypable. This can pose challenges in epidemiological investigations, as tracking the spread of specific strains becomes more difficult without the ability to serotype them. Researchers may need to employ alternative methods, such as genetic sequencing or other molecular typing techniques, to differentiate and track nonserotypable strains of bacteria. The term is most commonly applied to species like Haemophilus influenzae, where some strains are known as non-typeable H. influenzae (NTHi) and are a significant cause of mucosal infections.