Shigella
Shigellais a genus of bacteria that is Gram-negative, facultative anaerobic, non-spore-forming, nonmotile, rod-shaped and genetically closely related toE. coli. The genus is named after Kiyoshi Shiga, who first discovered it in 1897.
The causative agent of human shigellosis,Shigellacauses disease in primates, but not in other mammals. It is only naturally found in humans and gorillas. During infection, it typically causes dysentery.
Shigellosis is a bacterial infection that affects the digestive system. Shigellosis is caused by a group of bacteria calledShigella. TheShigellabacterium is spread through contaminated water and food or through contact with contaminated feces. The bacteria release toxins that irritate the intestines. The primary symptom of shigellosis is diarrhea.
Salmonella
Salmonellais a genus of rod-shaped (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. Salmonellaspecies are non-spore-forming, predominantly motile enterobacteria with cell diameters between about 0.7 and 1.5 μm, lengths from 2 to 5 μm, and peritrichous flagella (all around the cell body). They are chemotrophs, obtaining their energy from oxidation and reduction reactions using organic sources. They are also facultative anaerobes, capable of generating ATP with oxygen (“aerobically”) when it is available, or when oxygen is not available, using other electron acceptors or fermentation (“anaerobically”) get its energy.
The two species ofSalmonellaareSalmonella entericaandSalmonella bongori.S. entericais the type species and is further divided into six subspecies that include over 2,600 serotypes.Salmonellawas named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon.
Difference Between Shigella And Salmonella In Table Form
| ELEMENTS OF COMPARISON | SHIGELLA | SALMONELLA |
| Discovery | The genus is named after Kiyoshi Shiga, who first discovered it in 1897. | Salmonellawas named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon. |
| Motility | Shigellais non motile. | Salmonellais motile with peritrichous flagella. |
| Species | There are about 40 serotypes ofShigella bacteria | There are about 2,200 serotypes ofSalmonellabacteria |
| Shape | Shigellais slender bacilli microbe. | Salmonellais a rod shaped microbe. |
| Differential Media | In Hektoen agar, Shigellacolonies will appear green in color. | In Hektoen agar, Salmonellacolonies appear in black in color. |
| H2S Production | Shigelladoesn’t produce H2S. | Salmonellaproduces H2S. |
| Disease | Shigellacauses Shigellosis. | Salmonellacauses Salmonellosis. |
| Transmission | Shigella can be transmitted through contaminated food and water, personal contact even from animals. | Salmonellais transmitted by raw food whileShigellabyperson to person contact. |
| Major pathogen | Shigella dysenteriae | Salmonella typhi |
| Reservoir of organism | Human and primates only. | Human and animal. |
| Toxin Production | Shigellaproduces heat labile toxin called Shiga toxin. | Salmonellaproduces enterotoxin. |
| Effect on Human Intestine | Salmonellaaffect small and large intestine (enterocolitis). | Shigellaaffects colon (colitis). |
| Incubation Period | The incubation period for Shigella is 1-2 days. | The incubation period for Salmonella is 6-72 hours. |
| Dosage | Shigellarequires smaller infective dosage than forSalmonella. | Salmonellarequires larger infective dosage than forShigella. |
| Bloody And Mucoid Diarrhea | Bloody and mucoid diarrhea is more likely in shigellosis than salmonellosis. | Bloody and mucoid diarrhea is more likely in shigellosis than salmonellosis. |
Similarities Between Shigella And Salmonella
- Both are facultative anaerobic and non-spore forming organisms.
- SalmonellaandShigellaare different groups of Gram-negative bacteria.
- BothSalmonellaandShigellacan be transmitted through contaminated food and water, personal contact or even from animals and objects (fomites).
- Salmonellosis and shigellosis are more likely to occur in children under 5 years of age and the elderly.
- Diarrhea, abdominal pain and fever are the main symptoms in both diseases.
- The symptoms of both diseases resolve within 7 days or less in most people.
- Deaths in both diseases are uncommon but are more likely to occur in children with shigellosis.