Salmonella – Citrobacter (Continued)


This typing is to determine by slide agglutination specificities of 0 and H antigens and to recognize the serotype reference to Table Kauffmann-White. Typing is performed with Salmonella collected on plain agar slope (the moisture content allows a good development of H antigens) rather selective medium. The lack of self-agglutination of the strain is checked.

Simplified typing

About 98% of the Salmonella strains isolated in humans belonging to serotypes identified by the use of typing sera following:

– Anti Vi serum

– Sera 0: 4.5 to 9 – 6,7,8 – 3,10,15.

– Sera H: b – d – i – G – Ll.

Typing by the conventional method

Antigens 0

The first is to use polyvalent sera 0 called OMA, OMB, WTO, etc.

After agglutination in one of these sera corresponding monovalent sera were tested to determine the group of Kauffmann-White table belongs to the strain.

– H Antigens

Similarly using polyvalent sera H called HMA, HMB, HMC etc. then monovalent sera contained in the polyvalent serum where agglutination was observed.

For the phase inversion by the method of Sven Gard, one called SG sera 1-6 containing agglutinins corresponding to the already determined phase is added to the agar.


1. Determination of the group 0:

Serum mixtures are often unnecessary. The use of three sera (04.5 – 06,7,8 – 09) is used to group more than 90% ofSalmonella isolated in France.

2. Identification of serotype Typhimurium 1.4, [5], 12: i: 1,2:

In Group B (04), the most common serotype Typhimurium is far.

– Minimum Determination (during epidemics like now):

The agglutination with an anti-H i is sufficient serum.Indeed, other serotypes having 04 and Hi (Lagos, Agama, Farsta, Tsévié, Gloucester) are extremely rare.

– Complete determination:

After identifying Hi, seek a second binder phase with the HI mixing and monovalent serum H2. It is often necessary to immobilize the bacteria having Hi by Sven Gard method to make “run” those Hl, 2.

3. Identification of serotype Enteritidis 9.12: gm – Dublin and 9.12: gp –

In Group D (09), it is essential to distinguish Dublin Enteritidis (clinical manifestations are sometimes very different).

It is important to know that the anti-H gm agglutinates both serotypes serum (g common), and for anti-H serum gp. So we can not stop the diagnostic view of agglutination in gm or gp.

We can do without a G serum mixture (too much coagglutinations, agglutination does not mean that there is a g factor present)

Always use anti-H sera gm, anti H m, and anti-Hp p.

We have the following results:


Sera have: 0: 4.5 – 6.7,8 – 9 H: i – g m – m – p

Vi (mostly not miss a Typhi)

Examples of results of sero-diagnosis and their interpretations but not exclusive (By Pr. L. Le Minor, Proceedings of the national quality control in bacteriology)
Examples of results of sero-diagnosis and their interpretations but not exclusive (By Pr. L. Le Minor, Proceedings of the national quality control in bacteriology)

1) Typhoid fever to the state period.

2) paratyphoid fever B to the state period: coagglutination TO due to common factors 0 (12)

3) Three assumptions at least consider:

a) Typhoid fever in the beginning, to the 8th day; 0 agglutinins appeared, H agglutinins are not yet: a new serodiagnosis performed a few days later will highlight them.

b) infection with a Salmonella serotype having the antigen with S. typhi 0 common but different H antigen; search in this case if the suspension H S. Enteritidis (in Group D, S. Enteritidis is a frequent serotype) is not agglutinated.

c) Infection with Yersinia pseudotuberculosis (Bacillus Malassez and Vignal), Type IV: intradermal do.

4) at least three hypotheses:

a) Paratyphoid B early with coagglutination TO. See 3a.

b) Even reasoning 3b. Agglutination research 5.

Typhimurium H.

c) Even reasoning 3c with Y. pseudotuberculosis type II

5) Vaccinated the TAB for over three months: 0 agglutinins have disappeared, H agglutinins persist for many years.AH agglutinins may be absent, the vaccine containing less than that of A and T B.

6) Vaccinated at TAB nevertheless making typhoid fever following a massive uptake of S. Typhi highly virulent.

7) at least three hypotheses:

a) A former patient who is typhoid fever and having kept the serological brand, as if he had received a single vaccine T.

b) Infection due to Salmonella with the antigen H: d common with S. Typhi, but a different antigen 0 TABC: try to isolate the bacteria, especially in stool.

c) Typhoid fever treated early with chloramphenicol and chloramphenicol + corticosteroids. 0 agglutinins may not show them. If a new serodiagnosis shows a clear rise of agglutinins TH, if clinical and haematological signs are in favor of typhoid fever, this ascent makes it probable diagnosis. But we can tell, the same rise as may occur in the case 7b.


I. Each isolation of Salmonella and Shigella must be reported to Reference Center:

His address:

National Reference Centre for Salmonella and Shigella

Unit Enterobacteriaceae

Pasteur Institute in Paris

28, rue du Docteur Roux

75724 PARIS Cedex 15

II. Several cases are possible:

1) It is a ubiquitous Salmonella.

She shows no abnormalities: identification of typical gallery, without susceptibility anomalies, serotype diagnosis without problem.

It is not a Salmonella belonging to serotypes Typhi, Paratyphi A or B.

Complete the accompanying sheets provided by the Reference Center, and send them to the Reference Centre.There is no need to attach the strain.

2) It is a Salmonella belonging to serotypes Typhi, Paratyphi A or B.

The cover sheet will be thoroughly satisfied. It will be addressed with the strain in Reference Centre for lysotypique study.

3) It is a Salmonella which we can carry out serotyping.

Carefully fill the accompanying note by reporting agglutination observed. Address the strain Reference Center.

The identification of Salmonella serotypes (human) are performed free of charge provided that a minimum study was made ​​(serum agglutination sought with 0: 4.5 to 0: 9-0: 6,7,8).

4) It is a collective food poisoning or a nursery epidemic.

Carefully fill the information sheet.

Eventually, complete on a handwritten card with the notions of epidemiological interest that you obtained.

Do not forget to indicate the number of cases observed.

Address the strain Reference Center.

If the epidemic continues: after the initial mailing, regularly send information sheets, stating “Continuation of the epidemic – For information”.

If the changes appear in the behavior of strains in doubt, contact strains that appear abnormal, the Reference Centre.

5) It is a Shigella.

Check for mobility, the negativity of the LDC and citrate Christensen (differential diagnosis Aïkalescens-dispar).

If this is an isolated case of Shigella sonnei without diagnostic problem, complete one sheet and send ONLY without the strain, the National Center “For information, unaddressed strain.”

If there is an epidemic Sh. sonnei address all strains biotypie and phage typing, with a covering letter giving all relevant information.

If Sh. dysenteriae, Sh.flexneri, Sh. boydii, we must address the precise identification serotype strain.

III. Remarks:

1. How to send your crops.

No plates.

No stock.

Only solid media suitable: Ordinary agar inclined screw capped tube.

Or better medium tube for conservation of bacterial strains.

(Pasteur Diagnostics, tube 95 x 8). Wrap the tube in which the plug is locked in the absorbent paper. Insert the assembly in a metal case, itself placed in a second packaging of wood or plastic (Official Bulletin PTT)

2. The epidemiological data is stored in the database and used for epidemiological information and prevention.

It is important to complete as fully as possible the cover sheet, always mentioning the geographical origin of the contamination. Examples:

– Sick returning from Calcutta hospital in Pont-1’Abbe.

– Sick capita Le Touquet, hospitalized in Arras.

– Strain isolated in Paris, frog legs imported from Pakistan.

– Waste water collected and analyzed in Saumur Angers.

NOTE ON Citrobacter:


This kind brings together three species Enterohacteriaceae that the following characters: citrate (+) glucose fermentation with gas, mobility (+), ONPG test (+), negative VP reaction and lack of LDC.

There are many atypical strains of Citrobacter. Those negative ONPG and produce H2S can be confused withSalmonella. Some strains may be H2S negative, or negative Simmons citrate or agazogènes. Refer to the table that gives the characters to distinguish the two genres.


Citrobacter are commensal bacteria of the gastrointestinal tract of humans and warm-blooded animals. They are found in the environment and in the water. They can be isolated occasionally urine or various suppurations.


The type species, C.freundii, grows on usual medium giving a foul odor. The production of H2S and the absence of indole production permetttent to distinguish with C. diversus and C. amalonaticus. The table below gives the differential characteristics between the three species.