41 Questions
Which of the following best describes commensal organisms?
Microbes that adhere to body surfaces and form stable polymicrobial communities
What must a microbe do to act as a pathogen?
All of the above
What is the term for the ability of a microbe to damage a host?
Pathogenicity
Which of the following are considered virulence factors?
Adhesins, toxins, and capsules
What is the main cause of tissue damage in bacterial infections?
Inflammatory response
How do bacteria enter the body during infection?
All of the above
What are the possible outcomes when bacteria enter where they shouldn't?
Quick clearance or clinical disease
Which cells are involved in the response to bacterial infections?
Neutrophils and macrophages
What is the term for the relative capacity of a pathogen to damage a host?
Virulence
What are the clinical consequences of bacterial infection?
Tissue damage and immune response
Which type of neutrophils increase in a regenerative left shift?
Segmented neutrophils
What change in neutrophil morphology is seen in a degenerative left shift?
Increase in immature neutrophils
What can cause foamy cytoplasm in neutrophils?
Toxic change
What are Döhle bodies in neutrophils?
Focal blue-grey cytoplasmic structures
In which of the following conditions can Döhle bodies be a normal finding?
Healthy cats
What is a possible cause of coagulopathy in sepsis?
Stimulation of prothrombotic factors
Which of the following is a possible reason for a person to be a carrier of a bacterial infection?
They have a subclinical infection
What are some pathognomonic clinical presentations of bacterial infection?
Both systemic and localized inflammatory responses
What type of inflammation is associated with the presence of neutrophils and acute inflammation?
Pus formation
What are some cardiovascular consequences of bacterial infection?
Both congested mucous membranes and toxic line in gums
What are some clinical pathology findings associated with inflammation in the blood?
All of the above
What is the difference between bacteraemia and septicaemia?
Bacteraemia is the presence of bacteria in the blood, while septicaemia is the replication of bacteria in the blood
What is the typical neutrophil concentration in circulation for a dog?
3.0-11 x 103/ul
In which species is neutropenia typical in inflammation regardless of severity?
Cow
What are the three steps for cells to leave blood vessels?
Marginalisation, adhesion, migration
Which factors can produce a shift from the marginal to circulating pool of cells?
Epinephrine, glucocorticoids, infection
What are the potential reasons for a person to be a carrier of a bacterial infection?
Subclinical infection or latent infection
What are the clinical presentations of bacterial infection?
Inflammatory response, systemic and local symptoms, pus formation, granulomas
What are the cardiovascular consequences of bacterial infection?
Congested mucous membranes, toxic line in gums, septicaemia
What are the clinical pathology findings associated with inflammation in the blood?
Changes in neutrophil count, acute phase proteins, acid base and coagulation abnormalities
What are the three steps for cells to leave blood vessels?
Marginalisation, adhesion, migration
What are some possible causes of neutrophil toxic change in blood samples?
Rapid neuropoiesis, severe bacterial infection, injection of G-CSF
What are Döhle bodies and when can they be seen in blood samples?
Döhle bodies are focal blue-grey cytoplasmic structures (RER/RNA) that can be seen in some healthy cats.
What are some possible causes of asynchronous nuclear maturation in neutrophils?
Bacterial infections (Ehrlichia, Anaplasma, anthrax), viral infections (canine distemper), protozoal infections (Toxoplasma, Hepatozoon), fungal infections (Histoplasma), and hereditary/metabolic disorders (Chediak-Higashi, Birman cat anomaly, mucopolysaccharidosis).
What is the main cause of coagulopathy in sepsis?
Inflammation, which is a procoagulant state that can lead to microthrombi formation, lower platelet counts, and consumption of coagulation factors.
What is the difference between degenerate and non-degenerate neutrophils in tissue samples?
Degenerate neutrophils have finely granular nuclear chromatin but are in 'segments,' while non-degenerate neutrophils have dispersed organelles, persistent cytoplasmic RNA, and diffuse cytoplasmic basophilia.
Define commensal organisms and explain their role in the human body.
Commensal organisms are microorganisms that colonize the human body without causing harm. They form stable communities known as normal microflora, which are present on the skin and in various body cavities. These organisms play a beneficial role in maintaining health by competing with potential pathogens and contributing to immune system development.
What are the requirements for a microbe to act as a pathogen?
For a microbe to act as a pathogen, it must find an appropriate niche within a host, compete with the normal microflora, evade or overcome host defenses, and express genes that encode factors causing disease.
Explain the concept of pathogenicity and virulence.
Pathogenicity refers to the ability of a microbe to cause damage to a host. Virulence, on the other hand, refers to the relative capacity of a pathogen to cause damage. Virulence factors, such as adhesins, toxins, and capsules, are bacterial traits that confer pathogenicity.
Describe the different ways bacteria can invade the human body.
Bacteria can invade the human body through different mechanisms. They can enter between cells of the epithelium (paracellular), crack open cells to gain entry, or take advantage of widened gaps during an inflammatory response. Some bacteria can also enter cells in the body.
What are the possible outcomes when bacteria enter where they shouldn't?
When bacteria enter areas where they shouldn't, they can be quickly cleared by the immune system. However, if they are not cleared, clinical disease can occur, which may manifest as acute, subacute, or chronic infections.
Test your knowledge on the difference between commensal organisms and infections. Learn about the role of commensals in our body and how pathogens cause diseases.
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