Bacteriology II

What is pathogensis?

The process by which a microorganism causes disease in a host

What is the overall outcome of the pathogen’s life cycle in the host

Damage to the host due to invasion, immune evasion and microbial growth

What does virulence mean

The degree of pathogenicity of an organism

Give examples of gram positive infectious bacteria

Streptococcus and staphylococcus

Give examples of gram negative infectious bacteria

Neisseria and Escherichia

How do gram-negative cocci typically appear on a gram stain

As aerobic diplococci

What are coliforms

A subgroup of enterobacteriaceae describing gram-negative bacilli

What causes the drop in blood volume during sepsis

Small blood vessels become leaky, leading fluid loss into tissue

How do cytokines contribute to fever once released

They travel to the anterior hypothalamus and induce release of prostaglandins E

Why does the body begin to shiver at the onset of fever

Because the increased thermal set point makes the body perceive itself as cold

How are streptococcus species commonly identified in the laboratory

By their pattern of haemolysis

What is streptococcus pneumoniae and what haemolysis does it show

A major cause of pneumonia, it is alpha haemolytic

Example of non-haemolytic strep

Enterococci

What test helps identify staphylococcus aureus and what is its result?

The coagulate test and its coagulase-positive

What type of bacteria are clostridioides

Gram-positive anaerobic bacilli

What makes clostridioides species dangerous to human tissue

They produce exotoxins

Why is pneumococcal pneumonia clinically important

It causes acute inflammation of the lungs and is often resistant to penicillin