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| Question | Answer |
| What is the microscopic appearance of Salmonella? | G- Rod shaped with peritrochous flagella |
| Tests for Salmonella | Cat + Ox - H2S + Lac - Urease - Motility + |
| What is the serotype naming system based on? | O and H antigen |
| Where is it found in environment and how is it transmitted? | In fecal contaminated environment and contaminate feed, water, eggs, milk, fresh and processed meat- survives heat. Transmitted through alimentary route, colonizes ileum and caecum & lymphoid tissue. Has acid-shock proteins for protection against low pH in intestines. |
| What are 2 categories we can distinguish and which one causes gastroenteritis? | Typhoidal & Non-typhoidal. Non causes disease. |
| What are 3 clinical manifestations of Salmonellosis? | Gastroenteritis, bacteremia, asymptomatic carrier stage. |
| What does Salmonellosis cause? Who is more likely to be infected? | ~ Diarrhea, enteric fever, gastroenteritis, vomiting, abdominal cramps, abortion. ~ Elderly, infants and immunosuppressed individuals. |
| What is the appearance of Salmonella on XLD ? Why? | Black colonies : It is a hydrogen sulphide producer= grow colonies with a black centre because the medium contains an iron salt |
| What is the appearance of Salmonella on BPLS aka BGA agar? Why? | Red colonies= bacterium does not ferment lactose or sucrose & alkalinity |
| What is the result on TSI agar with salmonella? | Blackening of medium= production of hydrogen sulphide- H2S |
| What is important before inoculating on agars? | To firstly replicate in broth for isolation: rappaport medium- 12-24h at 44°C |
| What are incubation conditions and appereance on BAP? | 37°C FOR 24-48h. Medium, grey, circular colonies w/o hemolysis. |
| What is appearance on MCC? | Colourless colonies = Lac - |
| How can we identify Salmonella? | PCR, RT-PCR, rapid slide agglutination |
| Virulence factors of Salmonella: | ~ Enterotoxin- diarrhea ~ Siderophores- iron carrier ~ Fimbriae ~Cytotoxin ~Capsule antigen- DUBLIN& TYPHI ~H&O antigen: O=LPS=endotoxin ~Anti-phagocytic ~Injectosome- inject toxins in host cell ~ SPI- salmonella pathogenetic islands:clusters of virulence genes on chromosomes or plasmids= total 18 islands |
| What Abs do we use for treatment? | Must do a susceptibility test since some plasmids code for multiple resistance |
| What are 2 species of salmonella? | Enterica & Bongori |
| What are the Typhoidal serovars of S.enterica sbsp enterica? | ONLY Typhi & Paratyphi Typhoid and paratyphoid fevers |
| What are the Non-typhoidal serovars of S.enterica sbsp enterica? | Typhimurium & Enteritidis & all rest |
| Name serovars and hosts of S.enterica sbsp enterica | ~ Dublin -cattle ~ Choleraesuis- pig ~ Typhimurium - all ~ Enteritidis - Ho, rodents ~Heidelberg - Ho, pigs ~ Typhi - human ~ Paratyphi - human |
| What is Typhoid fever? | Caused by Typhi serovar of S.enterica sbsp enterica. High fever for several days, weakness, abdominal pain, constipation, headaches. Can last weeks/months w/o treatment. There are also latent carriers. |
| Where is S.bongori found? | ONLY in COLD-blooded animals. Reptiles are carriers of salmonella and a possible source of infection- part of their normal flora. |
| After infecting the intestines, where else can it go? | Lymph and blood. Will get ingested by macrophages and neutrophils but only neutrophils can kill it, it can survive in macrophages. |
| What happens when we have salmonella replicate in lympho nodes? | Nothing, it's the asymptomatic carrier state BUT stress can activate it and move to muscles - raw meat! |
| How does in initiate inflammatory response? | Penetrates into lamina propria of gut= diarrhea. Causes acute inflammation-> adenyl cyclase and prostaglandins/cytokines invade after release of enterotoxins |
| After infection of blood-septicemia what happens? | Goes to brain and meninges, pregnant uterus, joints and causes meningoencephalitis, abortion, osteitis and dry gangrene in extremities. |
| What does salmonella require to multiplicate? | 8°C |
| What samples do we use for detection? | blood and feces. Necropsy samples from intestinal contents and tissue lesions, and abomasal contents from aborted ruminant fetuses. |
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