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U.S. Department of Health and Human Services

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BBB - Streptococcus spp

Bad Bug Book:
Foodborne Pathogenic Microorganisms and Natural Toxins Handbook
Streptococcus spp.

A new version of the Bad Bug Book was released in 2012, below is a previous version.


1. Name of the Organism:

Streptococcus spp.

The genus Streptococcus is comprised of Gram-positive, microaerophilic cocci (round), which are not motile and occur in chains or pairs. The genus is defined by a combination of antigenic, hemolytic, and physiological characteristics into Groups A, B, C, D, F, and G. Groups A and D can be transmitted to humans via food.

Group A: one species with 40 antigenic types (S. pyogenes).

Group D: five species (S. faecalis, S. faecium, S. durans, S. avium, and S. bovis).

2. Nature of Acute Disease:

Group A: Cause septic sore throat and scarlet fever as well as other pyogenic and septicemic infections.

Group D: May produce a clinical syndrome similar to staphylococcal intoxication.

3. Nature of Disease:

Group A: Sore and red throat, pain on swallowing, tonsilitis, high fever, headache, nausea, vomiting, malaise, rhinorrhea; occasionally a rash occurs, onset 1-3 days; the infectious dose is probably quite low (less than 1,000 organisms).

Group D: Diarrhea, abdominal cramps, nausea, vomiting, fever, chills, dizziness in 2-36 hours. Following ingestion of suspect food, the infectious dose is probably high (greater than 107 organisms).

4. Diagnosis of Human Illness:

Group A: Culturing of nasal and throat swabs, pus, sputum, blood, suspect food, environmental samples.

Group D: Culturing of stool samples, blood, and suspect food.

5. Associated Foods:

Group A: Food sources include milk, ice cream, eggs, steamed lobster, ground ham, potato salad, egg salad, custard, rice pudding, and shrimp salad. In almost all cases, the foodstuffs were allowed to stand at room temperature for several hours between preparation and consumption. Entrance into the food is the result of poor hygiene, ill food handlers, or the use of unpasteurized milk.

Group D: Food sources include sausage, evaporated milk, cheese, meat croquettes, meat pie, pudding, raw milk, and pasteurized milk. Entrance into the food chain is due to underprocessing and/or poor and unsanitary food preparation.

6. Relative Frequency of Disease:

Group A infections are low and may occur in any season, whereas Group D infections are variable.

7. Course of Disease and Complications:

Group A: Streptococcal sore throat is very common, especially in children. Usually it is successfully treated with antibiotics. Complications are rare and the fatality rate is low.

Group D: Diarrheal illness is poorly characterized, but is acute and self-limiting.

8. Target Populations:

All individuals are susceptible. No age or race susceptibilities have been found.

9. Food Analysis:

Suspect food is examined microbiologically by selective enumeration techniques which can take up to 7 days. Group specificities are determined by Lancefield group-specific antisera.

10. Selected Outbreaks:

For more information on recent outbreaks see the Morbidity and Mortality Weekly Reports from CDC.

11. Education and Background Resources:

Literature references can be found at the links below.

  • Loci index for genome  Streptococcus

    Available from the GenBank  Taxonomy database, which contains the names of all organisms that are represented in the genetic databases with at least one nucleotide or protein sequence.

  • Streptococcus A FAQ's from the CDC.

    What is streptococcus A? What sort of germ is it? How can an infection be diagnosed? How can the infections be treated?