Salmonella Flashcards
Why the classification of salmonella is very difficult?
Because there are more than 2500 types and some strains lose the motility, Vi antigen or O antigen.
On the basis of which antigen serotyping is done?
O antigen
How we’re going to classify them?
Those that cause the typhoid fever and those that cause the nontyphoidal salmonellosis
How salmonella typhi and paratyphi are transmitted?
- Fecal oral route
- Through the laboratory
Who are the reservoir?
Humans
Where bacteria are found in carriers?
In the gallbladder, the bile, and even in stones
Where bacteria are excreted? What do they contaminate?
From time to time, bacteria leave the gallbladder, and they are excreted in stool.
Feces can contaminate hands, water, food.
What are the clinical presentations?
Asymptomatic carriers
Typhoid fever
On what depends the infectious dose?
It is small if the person is taking antacids, or if intestines are perforated (frequent aspirin takes leads to ulcers in the intestines)
It is large otherwise
What’s the incubation period?
3 to 21 days
It depends on the host and the amount of ingested bacteria, the lesser the amount ingested the longer the incubated period.
How bacteria will cause a primary transient bacteremia?
The large inoculum overcomes the acidity of the stomach, bacteria penetrate to the submucosal layer of the intestine, then go in monocytes and macrophages causing primary transient bacteremia.
Is there symptoms during the primary transient bacteremia?
No it is asymptomatic
How bacteria spread anywhere in the body?
Bacteria take the control in monocytes and macrophages changing many of the proteins in these cells so they can multiply. Bacteria can thus spread anywhere in the body using macrophages as a way of transport.
Where do bacteria go?
They go to the reticuloendothelial system formed by the liver, the spleen, the lymph nodes, and the bone marrow.
How secondary persistent bacteremia occurs?
Bacteria will multiply in the reticuloendothelial system, then a flow of bacteria will pass to the blood causing is secondary persistent bacteremia.
What are the nonspecific GI symptoms?
Sore throat, nausea, sometimes vomiting, constipation for a few days that might be followed by a diarrhea
What are the specific symptoms?
High fever of 39 to 40.5°C for 4 to 8 weeks caused by monokines, hepatosplenomegaly caused by recruitment of mononuclear cells in the spleen and liver where bacteria are present, severe anorexia leading to weight loss, change of sensorium (hallucinations because of the high fever), 5 to 6 days after these manifestations, the patient develops rose spots on the abdomen which contains the bacteria, relative bradycardia.
The least symptoms are the intestinal ones
What are the complications?
Meningitis that participates in the change of sensorium
Pneumonia
Involvement of bones and joints (osteomyelitis)
UTI: S. Typhi and paratyphi cannot cause a UTI directly, but since they are motile, so whenever bacteria are being excreted in stool, they can reach the urinary tract.
The worst complication is that related to the vascular system
What do we have in the complete blood count?
The WBC count can be normal, but we usually have leukopenia.
Individuals with intestinal perforations might be infected by other bacteria leading to leukocytosis.
Anemia because of anorexia, it’s worse in the case of intestinal perforations.
What is their selective medium?
D SS medium