Pathology - Infectious Disease Flashcards
Gram positive bacteria have what kind of cell wall?
Gram positive bacteria have a cell wall outside a single phospholipid bilayer.
Gram negative bacteria have what kind of cell wall?
Gram negative bacteria have a cell wall sandwiched between phospholipid bilayers.
Most bacteria in the body are where? And of what kind?
Most bacteria (10 to the 14) are anaerobes in the GI tract.
Which specific receptors does HIV bind to on lymphocytes?
CD4 and CXCR4 on helper T cells.
What is “quorum sensing”?
The phenomena of communities of bacteria coordinating the secretion of autoinducer peptides that turn on specific genes in the population.
It is a method of bacterial virulence.
How to bacteria adhere to host cells?
Bacterial adhesins and pili are mechanisms by which bacteria adhere. N. gonorrhoea varies its pilus to escape immune clearance.
What is an endotoxin?
Endotoxins are LPS components of cell walls of G- bacteria with a variable CHO chain. Whilst low doses induce a productive inflammatory response, high doses can lead to shock, DIC, and ARDS.
What is an exotoxin?
Proteins secreted by the bacterium which effect a pathological response. They have 4 broad categories…
Elaborate on the different categories of exotoxin:
- Enzymes. Eg protease produced by S. aureus.
- Toxins that alter intracellular pathways. Eg AB toxins produced by Bacillus anthracis
- Neurotoxins. Eg neurotransmitter blockade in botulism and tetanus.
- Superantigens. These stimulate very large numbers of T cells leading to massive cytokines release. Eg Staph and TSS.
Which pathogens are associated with B cell immunodeficiency?
S. pneumoniae H. influenzae S. aureus Rotavirus Enterovirus
Which pathogens are associated with T cell immunodeficiency?
Intracellular pathogens.
Which pathogens are associated with complement deficiencies?
S. pneumoniae
H. influenzae
N. meningitidis
Which pathogens are associated with neutropenia?
S. aureus
Gram negative infections
Fungi.
Measles:
- Type of virus
- Transmission and Distribution
- Clinical manifestations
- Immune response
- RNA Polymyxovirus
- Transmitted via respiratory droplets, starts at respiratory epithelium then spreads via lymph systematically.
- Causes croup, pneumonia, diarrhoea, keratitis, encephalitis, and (hypersensitivity) rash.
- Antibody-mediated immunity protects against re-infection
Mumps:
- Type of virus
- Transmission and Distribution
- Clinical manifestations
- Paramyxovirus
- Spreads via respiratory droplets then to lymph then haematogenously.
- Infects salivary glands, tested, ovaries, pancreas, CNS.
Poliovirus:
- Type of virus
- Transmission and Distribution
- Clinical manifestations
- Immune response
- Spherical, unencapsulated RNA enterovirus.
- Transmitted via faecal-oral route and multiplies in intestinal mucosa then systematically or via retrograde neuronal travel.
- Invades CNS in 1% replicating in motor neutrons in spinal cord or brainstem.
- Attaches to CD155
Ebola:
- Type of virus
- Transmission
- Clinical manifestations
- Enveloped RNA virus, part of the viral haemorrhagic fevers family
- Transmission occurs via infected animals.
- Haemorrhage is mediated through endothelial damage and platelet dysfunction. Also causes profound cytokine release.
What is the most common opportunistic viral pathogen in AIDS?
How might it manifest in immune compromised patients?
CMV may manifest as a life threatening colitis or pneumonitis, hepatitis, chorioretinitis, and meningoencephalitis.
How does CMV cause immune suppression?
CMV can infect dendritic cells and cause transient but severe immune suppression.
Which 2 cancers is EBV associated with?
B-cell lymphoma and Burkitt’s lymphoma.
Adherence proteins, invasive enzymes, haemolysins, exfoliative toxins, enterotoxins, and super antigens are all virulence factors of..?
Staphylococcus aureus.
Which bacterial species colonises the female genital tract and can cause chorioamnionitis in pregnancy?
Streptococcus agalacticae (GBS)
Can also cause neonatal sepsis and meningitis!