26- Bacterial Ibfection Flashcards
What are the 2 circulating systems in lungs
Aorta for ox, pa for deox
How many people carry staph aureus opportunist
1/10
Give some properties of it
Gram +ve cocci
How is it diagnosed both non resistant and resistant
Through a catalase enzyme assay as it it positive
Methicillin plates used for mrsa strains
Which bacteria are people 18-20 at risk of and some properties
Neisseria meningitidis
Gram -ve (with lps) cocci
Where is it found asymptomatically and carried
Nasopharyngeal area in humans
What protects it from phagocytosis
Capsule
What can happen due to lps
Endotoxic shock/septic shcok if it occurs systemically. This is where vasodilation and circulatory collapse occurs
What sorts of cytokines cia tlr4 can cause this and how
TNFa by inducing neutrophil margination to the tissues and this has things like paf, lt, pg when degranulated
Septicaemia causes a haemorrhage rash. How
Blood clotting eg via paf activating platelets
Give some properties of strep pyogenes
Gram +ve cocci
Why is it different to aureus
Forms chains of cocci and is catalase -ve
Which article discusses strep pyogenes
Kanwal 2021
If not treated what 2 later things can strep p cause
Glomerulonephritis and rheumatic fever
What is rheumatic fever and glomerulonephritis
Carditis and damage to valves
Where ic complex with strep ag and ab damage the glomerulus in kidneyb
Where does it usually colonise when transmitted eg by droplets
Pharynx and genital mucosa
Which component does it have in its capsule which blocks phagocytosis
Hyaluronic acid
Which things cause toxic shock syndrome and also scarlet fever
Pyrogenic exotoxins it produces
How does strep invade tissue
Streptolysin
What things does it cause in urt
Pharyngitis and eventually otitis media
What is the name of the bacteria which form diptheria toxin
Corynebacterium diptheriae
If gets to systemic blood what can it cause
Fever and heart failure
Why are they gram +ve rods
Incomplete division causes a rod shaped
How can it cause airway obstruction and death
Forms a pseudo membrane around pharynx and tonsils
What are some properties of haemophilia influenzae
Gram -ve bacteria which is capsulared for protection
Where does it affect in airway
Sinuses and sometimes lower airway
Which 2 major issues does it cause
Meningitis and epiglottitis
Give an example of a gram -ve rod (unlike dip which is gram +ve)
Bordatella pertussis
What types of toxins does it produce
Both endotoxin eg lps and exotoxins too
What are the exotoxins useful for
The acellular vaccine
They infect the large airways and cause what if systemic
Whooping cough Vomiting , sub conjunctival haemorrhage (behind eye)
Strep pneumoniae is a gram +ve cocci. How is it differentiated from staph aureus
Catalase negative and also forms diplococci (2)
What sort of disease does it cause in children and adults
Children have invasive diseases like meningitis vs pneumonia in lower lungs of adults
Is it encapsulated
Yea
Which article discusses pneumoniae more
Weiser et al 2018
Where are pneumoniae commensals
On nasal epithelial usually at mucosal areas
What can cause it to go down lungs or systemic
Aspiration or bacteraemia into blood
What 3 major effects does it have
, meningitis, otitis media, pneumonia of lower lungs
Which virus can cause increased shedding of pneumoniae and spreading eg by mucus secretions
Influenza a
Which substance does it release to cause pro Inflam cytokines, and damage/death of endothelial and epi lung cells
Pneumolysin
How does iav also increase acquisition of it in nasopharynx
Upregulste receptors for pneumoniae to bind
Which bacteria is an acid fast bacteria not gram -ve or +ve
Myco tb
It doesn’t produce any toxins so how is it infectious
It’s cell wall which is waxy and have an outer lipid layer
What causes susceptibility to fast spreading myco tb
Hiv immunosupression
Where does myco live and evade
Macrophage lysosomes
Why is epiglottitis a major issue
Because this is what closes the trachea to stop food going down
Are there more viral or bacterial infections in urt
Viral but they cause secondary bacterial infections too
Which inflammation can cause blue discolouration
Laryngotracheitis
How can you diagnose things
Bacterial cultures of throat swabs, blood cultures too
Why would blood cultures be used eg if epiglottitis
Can show systemic release/ spread of infection of haemophilius inflenzae which causes things like meningitis too
Which sorts of viruses cause common colds
Rhinoviruses (100 seri types)
How do you distinguish this from things like covid, iav infection
Same sysmtooms but can cause fever, systemic issues like headaches or vomiting
What can occur from common colds in urt
Sinusitis and otitis media
What is sinusitis
Where infection spreads to sinuses around eyes and behind nose causing inflammatioj eg after common cold
Give the major causes of sinusitis
MORAXELLA CATARRHALIS
Strep pneumoniae, h influenza , strep pyogenes, staph aureus (all of them)
How is chronic sinusitis different
Mix of both aerobic and anaerobic organisms
What is moraxella catarrhalis a member of
Nesseriaceae family - same as meningitidis as gram-ve cocci
Is it aerobic
Yes
What enzymes does it have
Oxidase and catalase +ve
Is it a commensalism
Yea in the urt but can get to lrt
Why is penecillin not used for it but amoxicillin instead
Has b lactamase so antibiotic resistant usually
What things can it excacerbate aswell as cause sinusitis
Copd
Which article discusses moraxella and viruses in sinusitis
Mccauley et Al 2021
What % of sinusitis cases had previous viral uri
5-10%
Why do they cause this
They induce inflammation in mucosa and also bacterial proliferation in nasopharynx areas
Children who experienced sinusitis after viral uri had distinguished Microbiota taxa. Explain
Dominated moraxella and haemophilia and lower lactobacilales and prevotella specifies
What cellular damage means mucus isn’t removed from sinuses they get congested and inflammation also
Cilia damage eg afterbinfection
What sorts of treatments are there
Analgesics for the pain, decongestants, amoxicillin/antibiotics
What is otitis media
Middle ear inflammatikn
Name some causes
Strep pneumoniae, h influenza, s pyogenes, moraxella catarrhalis, common colds
How does infection spread to the middle ear
The Eustachian tube
How is it diagnosed and what do you see
Otoscope.
Can see redness and bulging of the tympanic membrane
If a long term infection can be pus or blood
Analgesics or antibiotics can be given for acute treatment. What is put in for recurrent
Grommet plastic tube which allows draining of pus, opening of Eustachian tube to stop hearing impairment
If no pus is present near pharynx/tonsils what does this mean
It isn’t tonsillitis but pharyngitis
What is the biggest cause of pharyngitis
B haemolytic strep pyogenes (can also be diptheriae tho)
Can it also be viral and fungal
Yes. Most cases are viral accompanied with a common cold or influenza
What is given if swollen lymph nodes seen there
Antibiotics as it indicates a bacterial issue eg strep which can be systemic
What can cover tonsils and pharynx
Tonsils can be covered by membranes / inflammatory exudate/ pus
Pharynx can be seen covered in ulcers on the walls
Why is it important to identify pharyngitis caused by strep eg with swollen lymph nodes
Causes other issues like rheumatic fever etc
Which antibiotic is given for this cause of tonsillitis/ pharyngitis
Penecillin G
Viruses not treated with antibiotics
What is the major cause of laryngitis causing loss of voice / hoarseness
Viral infections eg flu or cold
What bacteria can cause it
H influenza , strep, corynebacterium
Which article discusses link between viruses and density of bacteria in urti
Demuri et Al 2018
What % of urti have viruses detected
80%
What bacteria were increased in colonisation frequency by viruses like rv, influenzaA, corona
Strep pneumoniae eg in otitis media, h influenza and moraxella catarrhalis for sinusitis
