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E. COLI K antisera for counter current immunoelectrophoresis and slide agglutination

Most E. coli are enclosed in a capsule consisting of polysaccharides, also known as acid polysaccharides. The capsules can be variously shaped and be more or less heat stable.

E. coli K antisera consist of polyclonal antibodies produced in rabbits. The antisera are used for serotyping of the 67 known E. coli K antigens.

Product description

K antisera are polyclonal antibodies produced by immunising rabbits with whole formalin-killed cells expressing as much capsular polysaccharide as possible.

K antisera are supplied ready for use in 1 mL bottles, which is sufficient for at least 65 tests (50 tests for K9 antisera for slide agglutination).

We offer the full range of antisera for E. coli serotyping

High quality

All absorbed free of cross-reactions

We offer experienced technical support

How to use

K antisera are used for current counter immunoelectrophoresis and cannot be used for slide agglutination.

The only exception is K9 antisera, article number 84888, which can be used for slide agglutination for the EPEC strain O104:K9. K9 antisera for slide agglutination was developed during the O104:K9 outbreak in Germany in 2011, and is not for general serotyping of K9 capsules.

Product range

SSI Diagnostica has K antisera against all defined K antigens. The number of K antigens ranges from K2 to K103, but 32 numbers in the sequence are missing. This is because antigens, previously thought to be K antigens, have since then turned out not to be E. coli capsule antigens after all, but Klebsiella and E. coli fimbriae antigens, amongst others. The K antigens eventually proved not to be E. coli capsule antigens are K21, K58-K73, K75-K81, K86, K88, K90, K91, and K99.

E. coli K single antisera for slide agglutination

ProductNumber of
R*84888 K9 50 1 mL vial 

E. coli
 K single antisera for counter current immunoelectrophoresis, undiluted (for research use only)

Product Number of
R*55338K2651 mL vial
R*55339K3651 mL vial
R*55340K4651 mL vial
R*55341K6651 mL vial
R*55342K7651 mL vial
R*55343K8651 mL vial
R*55344K9651 mL vial
R*55345K10651 mL vial
R*55346K11651 mL vial
R*55347K12651 mL vial
R*55349K14651 mL vial
R*55350K15651 mL vial
R*55351K16651 mL vial
R*55352K17651 mL vial
R*55353K18651 mL vial
R*55354K19651 mL vial
R*55355K20651 mL vial
R*55356K23651 mL vial
R*55357K24651 mL vial
R*55358K25651 mL vial
R*55359K26651 mL vial
R*55360K27651 mL vial
R*55361K28651 mL vial
R*55362K29651 mL vial
R*55363K30651 mL vial
R*55364K31651 mL vial
R*55365K32651 mL vial
R*55366K33651 mL vial
R*55367K34651 mL vial
R*55368K35651 mL vial
R*55369K36651 mL vial
R*55370K37651 mL vial
R*55371K38651 mL vial
R*55372K39651 mL vial
R*55373K40651 mL vial
R*55374K41651 mL vial
R*55375K42651 mL vial
R*55376K43651 mL vial
R*55377K44651 mL vial
R*55378K45651 mL vial
R*55379K46651 mL vial
R*55380K47651 mL vial
R*55381K48651 mL vial
R*55382K49651 mL vial
R*55383K50651 mL vial
R*55384K51651 mL vial
R*55385K52651 mL vial
R*55386K53651 mL vial
R*55389K54651 mL vial
R*55388K55651 mL vial
R*78059K56651 mL vial
R*55390K57651 mL vial
R*55925K74651 mL vial
R*82335K82651 mL vial
R*55391K83651 mL vial
R*55392K84651 mL vial
R*55926K85651 mL vial
R*55393K87651 mL vial
R*55394K89651 mL vial
R*55395K92651 mL vial
R*55396K93651 mL vial
R*55397K94651 mL vial
R*55398K95651 mL vial
R*55399K96651 mL vial
R*55400K97651 mL vial
R*55401K98651 mL vial
R*55402K100651 mL vial
R*55403K101651 mL vial
R*55404K102651 mL vial
R*55405K103651 mL vial
*Products marked with an R are Resctricted, which means that we will be charging either an extra fee, require a minimum order volume, or a forecast forthe specific product. Please contact us if you have an inquiry for one of these products.


Click the question to get your answer

Antibodies can be frozen, but the process of freezing and thawing is damaging for the antibodies, and the titer will drop (even though not dramatically) due to decomposition.
SSI Diagnostica has not made further studies on this, and cannot guarantee the stability of the antisera, but we have experienced that the titer mostly stays at the same level if an antiserum is only frozen and thawn once.

We cannot guarantee that the titer of our antiserum is at the correct level when it has expired. Generally high-titer (undiluted) products keep the titer better than ready-to-use sera. Some antisera (especially H antisera) have a tendency to maintain the titer better than others (such as OK O86). Generally, some antisera can be used after the expiry date and some cannot. Since we cannot say which antisera that maintain the titer and which that do not, we recommend that you buy new ones. The problem in using expired antisera is that you will get false negatives without knowing it.

No, not unless you order large amounts. Please send an inquiry to

Yes, it is possible if you place an order in advance with the expected total volume for the period. In return we guarantee to keep the reserved lot for you.

Please send an inquiry. Depending on the needed volume, we might be able to develop the requested product. It can be anything from a new pool composition to a new antiserum.

Yes, you can buy all reference strains for the O, H and K antigens. We also have a database containing more than 62,000 wild type strains, which you can also buy.

If you buy ready-to-use sera, the sera can NOT be diluted.

The titer indicates how many times the serum can be diluted and still give a positive reaction.

The high titer products can be diluted according to the instructions listed on the packaging. The dilution rate varies from product to product, depending on how specific serum, the different rabbits have produced. If the high titer products are diluted more than stated on the packaging, SSI Diagnostica cannot guarantee that the antiserum captures all the wild type strains.

Antiserum consists primarily of IgG antibodies.

We recommend that you use the volume stated in the product insert. It is particularly important to note that if the dilution of the antiserum is too high it will not catch the weakest reactions. Further, you will experience a weak agglutination.

We offer a yearly training course. Contact us for more information.

 A reference strain is a microorganism defined to at least the genus and species level, catalogued and described according to its characteristics e.g. O, K and H serotype and stating its origin.
A test strain is generally used for quality control and performance testing of culture media or serving as a positive/negative control in a diagnostic kit ensuring that the performance of the test has been successful.
Wild type strains are isolates from patients, animals or other sources, and these are not well defined.

It can ususally be done within three weeks.

You should send the strain according to your national legislation. The strain should be transported in an ordinary transport medium (Stuarts, Cary Blair, lyophilised or likewise), and the package should be marked with an UN number corresponding to the content of the package.

SSI Diagnostica

The main advantages are:
1. We offer the full range of antisera for E. coli serotyping.
2. Reaction time for OK O antisera is only 10 seconds reducing the risk of false positive reactions leading to a more accurate result compared to other tests having a reaction time of 1 minute.
3. SSI antisera are absorbed and thus very specific.
4. We offer technical expertise and assistance / training.


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