Salmonella

Salmonellae are usually petrich flagellated (i.e. distributed over the entire cell surface) and thus motile, gram-negative rod-shaped bacteria that are classified according to the White-Kauffmann-Le Minor scheme (also called Kauffmann-White scheme) on the basis of the structure of their surface (O) and flagellar (H) antigens and differentiated into serovars on the basis of an antigen formula. As a rule, they cannot ferment lactose. Microscopically, they cannot be distinguished from other Gram-negative rod bacteria.

A total of about 2,500 serovars are currently known, forming a genus with the two Salmonella species:

• Salmonella (S.) enterica
• Salmonella bongori

form.

Salmonella enterica are again divided into 6 subspecies:

• ssp.arizonae (group IIIa)
• ssp.diarizonae (group IIIb)
• ssp.enterica (group I)
• ssp.houtenae (group IV)
• ssp.indica (group VI)
• ssp.salamae (group II)

Nearly all human pathogenic salmonellae are found in the septa s. enterica ssp enterica. The further subdivision into serovars results from the different antigen patterns. Antigen patterns:

• O ant igen (surface antigen; note: the O originally stood only for "without puff", meaning these bacteria do not swarm on an agar plate): More than 60 different types exist.
• H antigens (flagellar antigens): Their antigenic structure is characterized by 2 different protein groups: H1 antigens and H2 antigens.Both phases can occur singly or together. The H1 antigens are marked with lower case letters. Since these are not sufficient, they are also numbered (e.g. z1, z2 etc.). The H-antigens of phase H2 are identified by lower case letters and numbers.

• K-antigens (capsular antigens; also called Vi antigen, an additional surface antigen, which was initially held primarily responsible for virulence; however, it represents a special case of a capsular antigen) occur only rarely, but they characterize the Typhi and Paratyphi varieties.

By this serological differentiation, about 2,500 serovars can currently be differentiated (they were formerly called species) and listed in the Kauffmann-White scheme.

Significance: Infectious diseases caused by Salmonella range from relatively harmless localized enteritis to severe septic and severe cyclic general infections.

For practical medical reasons, in this respect, it is necessary to distinguish the genus Salmonella into:

• Typhoid Salmonella
• non-typhoidal (enteric) Salmonellae

useful. Non-typhoidal Salmonellae usually cause gastroenteritis in humans. These are also called salmonella enteritis or salmonellosis.

Typhoid Salmonella such as S.enterica Serovar Typhi short: S.Typhi and S.enterica Serovar Paratyphi A,B. or C , short: S. Paratyphi A- C on the other hand cause systemic infections with intestinal involvement.

The typhoid salmonellae (typhoid and paratyphoid) include:

• Salmonella enterica Serovar Typhi (S.typhi for short) Causes typhoid fever.
• Salmonella enterica Serovar Paraptyphus A (short S.Paratyphi A)
• Salmonella enterica Serovar Paraptyphus B (S.Paratyphi B for short)
• Salmonella enterica Serovar Paraptyphus C (S.Paratyphi C for short)
• Several other salmonella varieties (S.Enteritides, S.Typhimurium, S.Hadra)

Salmonellae are adapted for reproduction in both humans and animals. With the exception of S. Typhi and S. Paratyphi A, in which humans act as hosts, they also occur in the gastrointestinal tract of animals, in some cases in mammals, reptiles, birds and insects. Over 500 serovars have been shown to be human pathogenic.

Reservoir: The main reservoir of Salmonella is animals, although they rarely become clinically ill from it. Agricultural animals such as cattle, pigs and poultry and animal foodstuffs produced from them are therefore at the top of the list of possible causes of infection (Information RKI).

Route of infection: Infection occurs through oral ingestion of the pathogen. Salmonellosis is the classic food-borne infection. The dominant serovar in Germany, S. Enteritidis, is transmitted mainly via insufficiently heated eggs or dishes and preparations containing eggs, especially if these contain raw egg. The nationwide introduction of vaccination against salmonella in breeding poultry, laying hens, broilers and turkeys led to a significant decrease in human cases of S. Enteritidis from 2008 onwards.

The serovar S. Typhimurium, which is also frequently found in Germany, is often transmitted through raw meat or meat products that have not been heated or not heated sufficiently (e.g. minced meat, raw sausages fresh mettwurst). Even foodstuffs that are not primarily contaminated with Salmonella can pose a risk of infection through contact with infected people, contact with contaminated surfaces or contaminated other foodstuffs (so-called "cross-contamination").

In detail see below

• Typhoid Salmonella
• Enteritic (non-typhoid) salmonellae
• Salmonella, infection control and hygiene measures
• Kauffmann-White scheme

1. Böhme H et al (2009) Reptile-associated salmonellosis in a breastfed infant. Clin Pediatr 221:74-75
2. Heissenhuber A et al. (2005) Accumulated occurrence of illnesses with Salmonella enteritidis in hospitals and nursing homes in the district Oberallgaeu, Bavaria, in July 2004. public health 67:845-852s.
3. Hof H et al. (2019) Enterbacterales In: Hof H, Schlüter D, Dörries R, eds Duale Reihe Medizinische Mikrobiologie. 7th, completely revised and expanded edition. Stuttgart: Thieme p 398-427
4. Jansen A et al. (2005) Nation-wide outbreak of Salmonella Give in Germany. Z Gastroenterol 43:707-713
5. Robert Koch Institute (RKI): Outbreak of illness caused by Salmonella Enteritidis after consumption of bakery products. Epid Bull 3:223-244
6. Robert Koch Institute: Infectious Disease Epidemiology Yearbook for 2019, Berlin, 2020.
7. World Health Organization/Food and Agriculture Organization (WHO/FAO): Safe preparation, storage and handling of powdered infant formula - Guidelines. 2006