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4.1 Medical Microbiology > Acute URTIs - Nasopharyngitis and Pharyngitis > Flashcards

Acute URTIs - Nasopharyngitis and Pharyngitis Flashcards

1
Q

What is an upper respiratory infection

A

An infection located in the upper respiratory tract:
- mouth, nose, throat, larynx and trachea

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2
Q

What are the seven types of upper respiratory infections

A

nasopharyngitis
Sinusitis
Pharyngitis/tonsilitis
Laryngitis
Laryngatracheitis
Epiglottitis
Otitis Media

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3
Q

What are the four functions of the URT?

A

Breathing
Immunity
Digestion
Speech

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4
Q

Talk about the breathing functino of the URT

A

The URT is a natural air “filter” -> mucuos lining, nasal hairs, cilia etc

The URT moistens, warms and cleanses the air we breath in

URT delivers air to the lungs

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5
Q

Talk about the immune function of the URT

A

The pharynx houses lymphatic tissues that guard against infection by releasing T and B lymphocytes

alveolar macrophages found deeper down in lungs as well

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6
Q

What is the dgestion function of the URT?

A

Epiglottis and larynx work in tandem to prevent food or liquid entering the lungs

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7
Q

What is the speech function of the URT

A

The movement of air across the larynx cerates vibrations

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8
Q

List some of the protective mechanisms of the URT

A

Nasal hairs
Mucus lining
Convoluted passages
Cilia in trachea
Reflexes such as cough, sneeze, swallow
sIgA (IgA in secretions) and T lymphocytes
Antibacterial substances such as lysozyme and interferons
Alveolar macrophages
Normal microflora to compete for nutrients and space
Bacteriocidins

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9
Q

List some of the protective mechanisms of the URT

A

Nasal hairs
Mucus lining
Convoluted passages
Cilia in trachea
Reflexes such as cough, sneeze, swallow
sIgA (IgA in secretions) and T lymphocytes
Antibacterial substances such as lysozyme and interferons
Alveolar macrophages
Normal microflora to compete for nutrients and space
Bacteriocidins

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10
Q

List some of the naturally occuring flora of the nasal cavity
Compare this to in a RTI

A

Staphylococcus
Moraxella
Corynebacteria
Propionibacteria

In RTI: Viral pathogens present

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11
Q

What are some of the naturally occuring flora of the nasopharynx

A

Staphylococcus
Moraxella
Haemophilus
Streptococcus spp
Corynebacterium
Dolosigranulum
Rhinovirus

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12
Q

What is the makeup of the organisms found in the nasopharynx during a RTI

A

Much less diversity during infection
Haemophilus
Streptococcus
Neisseria
Oral-type anaerobes
Respiratory viruses such as RSV or influenzavirus

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13
Q

What are some natural flora of the oropharynx

A

Streptococcus
Neissera
Haemophilus sp
Prevotella

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14
Q

What are some natural flora of the oropharynx

A

Streptococcus
Neissera
Haemophilus sp
Prevotella

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15
Q

Who would you be most likely to finf S. pneumo as a commensal in?

A

Some young kids have S. pneumo in their nasal passage

These arent pathogenic and will only cause infection under the right conditions

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16
Q

Write a note on the epidemiology of URI

A

Account for half of all symptomatic diseases

The most common acute illness evaluated in the outpatient setting (GPs)

Children have been 6-8 episodes per year but can be 12+ etc etc

Adults have between 3-6 episodes per year

Used to be most common in September and March but since covid theyve become a year round infection

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17
Q

Whos most likely to get URIs?

A

Young children or those around them e.g. parents, child-carers or grandparents

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18
Q

Whos most likely to get URIs?

A

Young children or those around them e.g. parents, child-carers or grandparents

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19
Q

What are the three methods of transmission of URIs

A

Droplet transmission

Airborne Transmission

Contact transmission

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20
Q

How are URI transmissed through droplets?

A

Droplets are >5 microns in size

Coughing, sneezing, talking

Contact with mucous membranes

Travel 1-2 meters

Land on surfaces -> another person then touches the surface and picks up the organism

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21
Q

How are URIs transmissed through the air?

A

Aerosol generating procedures
Small in size
Remain airborne for longer then droplets
- aerosols inhaled into lungs of another person

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22
Q

How are URI spread through contact

A

Direct contact -> poor hand hygiene after touching an infected person

Indirect -> touching an object contaminated with droplets etc

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23
Q

What are the main risk factors of URI?

A

Close contact with children
Medical conditions
Smoking
Immunocompromised
Anatomical anomalies
Use of public transport

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24
Q

What medical conditions put you at higher risk of URI?

A

asthma
Allergic rhinitis (hayfever)

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25
What medical conditions put you at higher risk of URI?
asthma Allergic rhinitis (hayfever)
26
What immune conditions increase risk of URI?
Cystic fibrosis COPD HIV Corticosteroids Transplantation Post-splenectomy
27
Give some examples of anatomical anomalies which increase risk of URI
Facial dysmorphic changes Nasal polyposis
28
What are the two main acute URTIs?
Nasopharyngitis Pharyngitis
29
What headings should you give when writing about a specific URTI?
The infection Aetiology Epidemiology Sequela Laboratory Detection Treatment
30
Talk about nasopharyngitis, what is it and what are the symptoms
Known as the 'common cold' or a 'head-cold' Inflammation of the ciliated epithelial cells in nasal mucosa A short, mild, self-limiting infection characterised by nasal discharge, cough and a sore throat
31
Write a note on the aetiology of nasopharyngitis (3)
>85% caused by respiratory viruses Between 10 and 15% are less commonly caused by bacteria <1% of cases caused by rare viruses
32
What respiratory viruses cause >85% of nasopharyngitis? (8)
1 of 200 virus strains from 7 main families: Rhinovirus (30-50%) Parainfluenza Respiratory syncytial virus Coronaviruses Enterovirus Influenza virus Adenovirus
33
What bacteria cause 10-15% of nasopharyngitis?
Chlamydia pneumoniae Mycoplasma pneumoniae Streptococcus pyogenes
34
What rare viruses cause <1% of nasopharyngitis?
Mumps virus Rubella virus Rubeola virus Cytomegalovirus
35
What rare viruses cause <1% of nasopharyngitis?
Mumps virus Rubella virus Rubeola virus Cytomegalovirus
36
Why is nasopharyngitis caused by viruses such as mumps and rubella now rare to see
Nearly everyone should be vaccinated against these (MMR vaccine) We did have a drop of in people getting vaccinated but this has gone back up again
37
What are the five most common sequelae from nasopharyngitis?
Lower respiratory tract infection - most common Bronchial hyperreactivity/asthma flare Otitis media (5-19%) - more common in kids Acute sinusitis Pneumonia Eye infections in kids
38
How does nasopharyngitis become eye infections in young kids but is rarely seen in adults?
Thinkof how a young kid wipes their nose Snot straight into the eye
39
How does nasopharyngitis become eye infections in young kids but is rarely seen in adults?
Thinkof how a young kid wipes their nose Snot straight into the eye
40
Talk about the diagnosis of nasopharyngitis
Nearly always a clinical diagnosis or a symptomatic diagnosis by the patient themselves Rarely ever get a sample for investigation Can run biofire film array respiratory panel to detect viruses -> but realistically this is only really done to investigate something else and the virus comes up then accidentally There is also Rare rtPCR and ELIZA testing available but this isnt really done anywhere
41
Talk about the diagnosis of nasopharyngitis
Nearly always a clinical diagnosis or a symptomatic diagnosis by the patient themselves Rarely ever get a sample for investigation Can run biofire film array respiratory panel to detect viruses -> but realistically this is only really done to investigate something else and the virus comes up then accidentally There is also Rare rtPCR and ELIZA testing available but this isnt really done anywhere
42
How is nasopharyngitis treated?
Symptomatic therapy Rest, fluid, paracetemol only really treatment
43
What is pharyngitis?
Infection of the pharynx or tonsils Associated with pharyngeal pain and the appearance of erythema and swelling of affected tissues (tonsils) Sore throat - swollen lump on each side of throat
44
Comment on the aetiology of pharyngitis
70% of cases are viral 30% are bacteral Very rare cases are fungal
45
Comment on the epidemiology of pharyngitis
One of the most common conditions encountered by GP 16% of adults ad 41% of children report a sore throat over a 1 year time frame Incidence peaks between late winter and early spring
46
What viruses cause pharyngitis
Rhinovirus Adenoviruses (pharyngoconunctival fever) Coxsackie A and other enteroviruses (small vesicles - herpangia) EBV in 70-90% of glandular fever patients Herpes simplex 1 and 2 -> can be severe with palatal vesicles or ulcers
47
What is the telltale sign of adenovirus caused pharyngitis
Pharyngoconjunctival fever
48
What is the telltale sign of adenovirus caused pharyngitis
Pharyngoconjunctival fever
49
What is the telltale sign of Coxsackie or enterovirus caused pharyngitis
Small vesicles - herpangia
50
What is the telltale sign of Herpes caused pharyngitis?
Palatal vesicles or ulcers
51
What is the telltale sign of Herpes caused pharyngitis?
Palatal vesicles or ulcers
52
What is the treatment for viral pharyngitis?
Usually only symptomatic treament -> fluids, rest etc
53
What is the main cause of bacterial pharyngitis?
Group A streptococcus -> S. pyogenes
54
Talk about S. pyogenes pharyngitis, what symptoms does it cause
Main bacterial cause of tonsilitis Tonsillar exudate (white tonsils) Pyrexia, anorexia and dysphagia Painful cervical lymphadenopathy No cough -> just sore throat no other URI symptoms
55
Talk about S. pyogenes pharyngitis, what symptoms does it cause
Main bacterial cause of tonsilitis Tonsillar exudate (white tonsils) Pyrexia, anorexia and dysphagia Painful cervical lymphadenopathy No cough -> just sore throat no other URI symptoms
56
What are the risk facors for S. pyogenes pharyngitis?
Young age -> strep throat most common in children Time of yeaar -> circulates in winter and early spring Strep bacteria flourish where groups of people are in close contact
57
Comment on the aetiology of S. pyogenes pharyngitis
Causes of 700 million cases Worldwide per year - a significant amount of cases Isolated in up to 5-15% of adult and 15-30% of children
58
List the sequela of S. pyogenes pharyngitis
Quinsy Otitis media nad sinusitis Pneumonia Bacteraemia Meningitis Necrotising fasciitis Scarlet fever Rheumatic fever Endocarditis Glomerulonephritis
59
What is Quinsy?
A peritonsillar abscess A sequelae of acute bacterial tonsilitis caused by S. pyogenes
60
What is necrotising fasciitis?
Death of fibrous tissue beneath the skin and around muscle
61
Why do doctors tend to overprescribe antibiotics for pharyngitis without taking a throat swab?
GPs check for white on tonsils If white presence they give antibiotics even though this could still be a viral infection Fear of S. pyogenes which can cause severe sequelae if missed
62
What causes S. pyogenes scarlet fever?
The effects of pyrogenic(erythrogenic) toxin
63
What is Rheumatic fever
An autoimmune reaction due to S. pyogenes A sequela damaging the heart (arthtitis) Molecular mimicry whereby antibodies produced against S.pyogenes M-protein damage the human proteins (myosin) of the heart The build up of antibodies is what causes arthritis symptoms The autoimmune on cardiac cells causes inflammation known as endocarditis
64
What molecules are involved in molecular mimicry of S. pyogenes caused endocarditis?
S. pyogenes M-protein and cardiac cell myosin
65
Talk about S. pyogenes caused glomerulonephritis
PSGN or poststreptococcal glomerulonephritis results from a bacterial infection that causes rapid deterioration of kidney function due to an inflammatory response following infection Basically the infection causes glomeruli to become inflammed
66
Talk about S. pyogenes caused glomerulonephritis
PSGN or poststreptococcal glomerulonephritis results from a bacterial infection that causes rapid deterioration of kidney function due to an inflammatory response following infection Basically the infection causes glomeruli to become inflammed Antigen -> antibody produced -> Ag-Ab complex -> large complex -> glomeruli damaged
67
How does S pyogenes toxic shock come about?
S. pyogenes superantigen toxin is responsible This is recognised by T lymphocytes which release cytokines responsible for TSS symptoms
68
What three infections can occur from the metastatic spread of an S.pyogenes bacteraemia?
It can cross the blood-brain barrier and cause meningitis It can cause arthritis It can cause osteomyelitis
69
What three infections can occur from the metastatic spread of an S.pyogenes bacteraemia?
It can cross the blood-brain barrier and cause meningitis It can cause arthritis It can cause osteomyelitis
70
Talk about group C/G streptococcal pharyngitis
S. dysgalactie is the most common Causes about 3-5% of pharyngitis Similar in clinical features to GAS but sequelae not as severe genetically very similar to GAS -> prior to MALDI they were hard to distinguish from each other
71
Talk about group C/G streptococcal pharyngitis
S. dysgalactie is the most common Causes about 3-5% of pharyngitis Similar in clinical features to GAS but sequelae not as severe genetically very similar to GAS -> prior to MALDI they were hard to distinguish from each other
72
If you had a persistant sore throat what bacterial cause of pharyngitis would you be concerned with?
Fusobacterium necrophorum
73
Talk about the aetiology of F. necrophorum pharyngitis
Most likely cause of PSTS - persistant sore throat syndrome i.e. bacterial pharyngitis that re-occurs after treatment Obligate anaerobe GNB Quiet difficult to diagnose Main complication is Lemierre's Syndrome
74
What is the main complication of F. necrophorum pharyngitis?
Lemierre's Syndrome
75
What is Lemierre's Syndrome?
Where Fusobacterium spreads to a major blood vessel and causes blood clots in the bloodstream
76
Talk about Corynebacterium pharyngitis
C. diptheria most common Acute onset Characteristic pseudomembraneous tonsils and back of throat Not really a problem in ireland due to immunisation with toxoid vaccine but still sen due to foreign travel and immigration
77
Talk about C. diptheria complications
Bacteria release diptheria toxins A/B which can cause damage to myocardium, nerve endings and adrenal glands Grey adherent leathery pseudomembrane can block airways or can lodge in trachea/bronchi Death due to myocarditis and neurological complications Tracheostomy needed
78
Comment on epidemiology of C. diptheria pharyngitis
Very few cases since introduction of toxoid vaccine e.g. 0 cases in Ireland in 2019 16,000 cases worldwide in 2018 -> in unvaccinated and immunocompromised
79
Comment on epidemiology of C. diptheria pharyngitis
Very few cases since introduction of toxoid vaccine e.g. 0 cases in Ireland in 2019 16,000 cases worldwide in 2018 -> in unvaccinated and immunocompromised
80
What are the symptoms of C.diptheria pharyngitis
Sore throat Bull Neck Grey pseudomembrane
81
What are the 4 main sequelae of C. diptheria pharyngitis?
Damage to the heart muscle (myocarditis) Damage to the renal tubules (acute tubular necrosis) Nerve damage (nerve demyelination/polyneuropathy) Loss of the ability to move (paralysis)
82
Write a note on lab detection of bacterial pharyngitis
Throat swab = gold standard 97% specific and 95% sensitive on blood agar Containment level 2 lab
83
How should throat swabs be put up for pharyngitis investigation?
Blood agar incubated overnight anaerobically For query fuso a blood agar + metronidazol will be put up with extended incubation (48hrs)
84
How should throat swabs be put up for pharyngitis investigation?
85
What make you query a Corynebacterium pharyngitis?
Foreign travel
86
What three media would be suitable for confirmation of Corynebacterium?
Tinsdale Tellurite Hoyles
87
How would you confirm ID of a Group A Strep (6)
Gram + cocci in long chains Beta haemolytic on blood agar Bacitracin sensitive Lancefield group A Penicillin Sensitive PYR Test
88
Why do we incubate throat swabs anaerobically?
The streptolysins of strep demonstrate B haemolysis better when incubated anaerobically even though strep will still grow in CO2
89
Why do we incubate throat swabs anaerobically?
The streptolysins of strep demonstrate B haemolysis better when incubated anaerobically even though strep will still grow in CO2
90
What is the PYR Test?
Pyrrolidanyl Aminopeptidase Test
91
How would you confirm ID of Fusobacterium necrophorum?
Gram negative pleomorphic bacilli - all different sizes Strict anaerobes -> hence Mtz disc Non-motile Non-spore forming Beta haemolytic on BA Selective agars including vancomycin and nalidixin Characteristic odour (rancid butter or boiled cabbage) and flecked appearance
92
How would you confirm ID of a Corynebacterium Diptheria?
GPB Clubman shape Chinese lettering Aerobic or facultative anaerobe Tellurite Hoyles Tinsdale ELEK Plate for toxin investigation
93
How does Corynebacterium grow on Tinsdale
Black colonies surrounded by brown halos -> due to production of cysteinase which release H2S which interacts with salt in media
94
How will C. diptheria grow on Hoyle's?
C. diptheria mitis = black colonies with grey periphery C. diptheria gravis = large, grey colonies C. diptheria intermedius = small, dull, grey-black colonies
95
How will C. diptheria grow on Hoyle's?
C. diptheria mitis = black colonies with grey periphery C. diptheria gravis = large, grey colonies C. diptheria intermedius = small, dull, grey-black colonies
96
What is the ELEK plate for C. diptheria?
An immunodiffusion method involves applying filter paper soaked in anti-toxin to the plate
97
How is group A Strep treated?
Penicillin - usually works Erythromycin 1st gen cephaloporins Macolides
98
How is Fuso necrophorum treated?
B-lactam antibiotics Metronidazole Clindamycin 3rd Generation Cephalosporins
99
How is C. diptheria treated?
Erythromycin Antitoxin - given to revent further spread of toxin

4.1 Medical Microbiology (30 decks)

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