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M103 T4 > M103 T4 L8 > Flashcards

M103 T4 L8 Flashcards

1
Q

What are features of the Legionella pneumophila bacteria?

A 
thin
aerobic
flagellated
non-spore-forming
Gram-negative
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2
Q

What is unusual about the coating on Mycobacterium tuberculosis bacteria? What causes it?

A

is unusual and waxy

primarily due to the presence of mycolic acid

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3
Q

What are the symptoms of parainfluenza virus?

A

fever
runny nose
cough

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4
Q

What are the two main parts of the respiratory tract?

A

the upper respiratory tract

the lower respiratory tract

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5
Q

Why have we divided the respiratory tract into two main parts?

A

conditions in each part present differently to each other
different consequences in terms of morbidity and mortality
investigated and treated differently

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6
Q

What are the four functions of alveolar macrophages?

A

to secrete anti-microbial peptides
to engulf and kill pathogens
to recruit other immune cells
to process and present antigens to T cells

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7
Q

What secretes IgA?

A

plasma cells

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8
Q

Which atby is most commonly produced?

A

IgA

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9
Q

How does IgA help to enable immune function in the mucous membranes?

A

IgA secretions form an additional epithelial protective barrier

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10
Q

How does the additional epithelial protective barrier formed by IgA help to protect the cell?

A

prevents microbial adherence to the epithelial surface
inhibits certain viral infections by interfering with their assembling processes.
binds to pathogens causing phagocytosis
provides atby dependent, cell mediated cytotoxicity

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11
Q

What material is the mucosa made up of?

A

consists of one or more layers of epithelial cells

overlying a layer of loose connective tissue

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12
Q

What are the five things that the alveolar spaces fill up with when the lungs experience inflammation?

A 
exudate
pus cells
debris 
dead bacteria 
dead viruses
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13
Q

Why does inflammation in the lungs cause a loss of function?

A

the alveolar spaces fill up with different cells / matter

stops the alveolar spaces from being filled with air anymore

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14
Q

How does inflammation in the lungs cause pain?

A

there is no real pain sensation in the lungs themselves

the pain comes the outside of the lungs - pleuritic pain

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15
Q

What is pleuritic pain caused by?

A

inflammation causes swelling and sensitivity
the outside of the lung is inflamed with the infection below it
rub together
the friction causes pleuritic pain

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16
Q

During swelling, what is the effect of the alveolar walls becoming thicker than normal?

A

it impedes that gas transfer

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17
Q

What are the three causes of swelling on a microscopic level?

A

vasodilation
increased vascular permeability
inflammatory cell infiltration

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18
Q

Why does part of the lungs sometimes become lighter in colour during swelling? Why is this a problem?

A

because that part of the lung is full of pus
if the lighter section were to be squeezed, it would be really hard and solid
this means that this part of the lungs no longer has its usual squidgy air sponge anymore

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19
Q

What is a Pulmonary abscess caused by?

A

when a bit of dead / necrotic lung has died away and there is a pus filled abscess within that

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20
Q

How long is the incubation period for rhinoviruses?

A

incubation: 2 - 3

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21
Q

How long can symptoms last for rhinoviruses?

A

usually 3 - 10 days

it can be up to two weeks in 25 % of patients

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22
Q

What happens if bradykinin is administered internasally?

A

causes a sore throat

causes nasal congestion

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23
Q

How is sneezing mediated?

A

histamines are released

the trigeminal nerves are stimulated sensorily

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24
Q

When does nasal discharge change colour?

A

when there are increasing numbers of neutrophils due to myeloperoxidase

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25
What are the changing colours of nasal discharge due to myeloperoxidase?
white yellow green
26
What nerve mediates coughing?
the vagus nerve
27
What condition needs to be met for a cough to start?
any inflammation has to extend as far as the larynx to trigger coughing
28
What substance is responsible for systemic symptoms such as fever?
Cytokines
29
What is the difference between how fast symptoms appear for the cold compared to for the flu?
cold - appears gradually | flu - within a few hours
30
What is the difference between what areas of the body the cold affects compared to for the flu?
cold - affects mainly your nose and throat | flu - affects more than just your nose and throat
31
What is the difference between how the cold makes people feel compared to for the flu?
cold - feel unwell but okay to carry on as normal | flu - feel exhausted and too unwell to carry on as normal
32
What is the difference between how the cold and the flu in terms of fevers?
cold - usually no fever | flu - high fevers, may have lower respiratory tract features as well
33
What two viruses is influenza caused by?
Influenza A virus | Influenza B virus
34
How long is the incubation period for uncomplicated influenza?
1-4 days
35
What are the symptoms of uncomplicated influenza?
``` abrupt onset of cough and fever headache, sore throat, nasal discharge myalgia malaise acute debilitation otherwise examination often unremarkable ```
36
What is the temperature range for a fever caused by uncomplicated influenza?
38 - 41 oC
37
What are the risk factors for influenza?
``` Immunosuppression chronic medical conditions pregnancy / 2 weeks postpartum Age <2y or >65y (young or old) BMI >40 ```
38
What are the complications for influenza?
1o viral or 2o bacterial pneumonia CNS disease Death
39
What is the estimated mortality rate among people infected with influenza in the US?
about 0.13 percent
40
What is the function of the influenza virus haemagglutinin surface protein?
binds sialic acids on cell surface glycoproteins binds glycolipids in the respiratory tract AAR allows the influenza virus to enter the cell
41
What is the function of neuraminidase on the surface of the influenza virus?
allows the virus to escape by cleaving sialic acid bonds | so that the escaping virions won't all clump together
42
What features do the genome on influenza virus have?
a segmented genome consisting of 8 parts | can be reassorted if two different viruses infect the same cell (the genetic material will mix)
43
What is the difference between antigenic shift and antigenic drift?
shift - whole segment switch | drift - many small point mutations
44
How does antigenic drift work?
when RNA viruses are a little bit careless about how they replicate causes little point by point mutations each time they replicate over time, it just slowly changes what sitting on the outside of the virus neutralising atbys used to block binding fo the virus to cells however, mutations can alter the haemagglutinin epitopes enough so that neutralising atby no longer binds
45
What are the options for treatment and prevention of influenza?
hand hygiene droplet precautions (spreads by droplets) active immunisation
46
What does active immunisation treatment for influenza work against?
haemagglutinin components | neuraminidase components
47
What are the symptoms of pneumonia?
Fever (cytokines) breathlessness (alveoli full of matter) cough (trying to cough up alveolar content) sputum production (mucociliary escalator tries to get rid of alveolar content in the trachea) Hypoxia - increased respiratory rate Pleuritic chest pain Sepsis
48
Radiologically, what does a diagnosis of pneumonia require?
infiltrates on a plain CXR with supporting clinical features
49
Why can the heart borders or diaphragm become obscured on CXRs?
due to loss of solid-gas interface the alveoli and bronchioles are completely filled with inflammatory debrision, so they look solid what usually is solid next to gas is now solid next to solid
50
What are the three types of classification for pneunomia?
Typical versus atypical *lecturer said not helpful Lobar versus bronchopneumonia * Community versus hospital-acquired
51
Why is the pneunomia classification Community / hospital-acquired the most useful classification?
the pathogens involved differ in their % contribution | so it alters their management
52
What are the Community-acquired pneumonia pathogens?
``` Streptococcus pneumoniae Haemophilus influenzae Mycoplasma pneumoniae Legionella pneumophila Staphylococcus aureus ```
53
What proportion of pneumonias are caused by respiratory viruses?
about a third
54
Why are all pneumonias treated with antibiotics even though a third are viral?
it's really hard to tell whether it's whether bacteria or viruses are causing the pneumonia most of the time
55
What is the most common organism overall?
Streptococcus pneumoniae
56
What are the risk factors of Streptococcus pneumoniae?
``` alcoholism respiratory disease smoking hyposplenism chronic heart disease HIV – 50- to 100-fold increase in invasive pneumococcal disease in HIV+ ```
57
What type of bacteria is Streptococcus pneumoniae?
Gram positive cocci
58
How is Streptococcus pneumoniae prevented and how is it treated?
prevented - vaccine | treated - penicillin
59
Where is Streptococcus pneumoniae acquired?
in the nasopharynx
60
What proportion of people with Streptococcus pneumoniae are asymptomatic carriers?
40-50%
61
What is the most common cause of atypical pneumonia?
Mycoplasma pneumoniae
62
How does atypical pneumonia usually present?
young patient with a vague constitutional upset lasts for several weeks extrapulmonary symptoms very common
63
Why is atypical pneumonia penicillin resistant?
it lacks a cell wall | penicillins need a cell wall to work on
64
Why can't atypical pneumonia be diagnosed in the usual way in a lab?
it lacks a cell wall | so it cannot grow on normal lab plates
65
How is atypical pneumonia diagnosed?
by PCR of throat swab (VTS) | involves looking for the genome rather than trying to grow it
66
How is atypical pneumonia treated?
macrolides or tetracyclines
67
In which two ways can Legionella pneumophila occur?
as sporadic infection | in outbreaks associated with a contaminated water source (consider travel and nosocomial acquisition)
68
What is a potential effect of Legionella pneumophila?
Can cause severe, life threatening infection
69
How common is Legionella pneumophila?
350 cases/year in E&W
70
How is Legionella pneumophila diagnosed?
doesn't grow on routine culture – need special conditions, and longer Urinary legionella antigens - urine is tested for L.p antigens using a lateral flow assay
71
How is Legionella pneumophila treated?
macrolides or quinolones
72
What are the risk factors of Legionella pneumophila?
smoking | chronic lung disease
73
What condition has to be met for it to be Healthcare-associated pneumonia?
has to have onset at least more than 48 hours since admission
74
How do patients catch Healthcare-associated pneumonia?
Hospitalised patients become colonised with hospital bacteria the longer they stay they may either be intrinsically more resistant to antibiotics, or have acquired resistance mechanisms. these organisms then develop into pneumonia
75
How is Healthcare-associated pneumonia treated?
a broader spectrum antibiotics are used instead
76
What are the social risk factors for pneumonia?
Current EtOH misuse Current or hx of drug misuse Homelessness Imprisonment
77
What are the risk factors for pneumonia?
More pulmonary disease Higher MDR rates Poorer treater completion rates Poorer outcomes even in drug sensitive TB
78
How often does Aerobic bacillus divide?
every 16-20 hours | very slowly
79
Why doesn't Aerobic bacillus stain strongly with Gram stain?
it has a cell wall, but it lacks the PPLPD outer membrane
80
Why is Aerobic bacillus referred to as acid fast bacillus (AFB)?
it retains the gram stain after treatment with acid any other bacteria that (stain) will wash away (weakly positive)
81
Which two special stains are used for Aerobic bacillus?
Ziehl-Neelsen | auramine-rhodamine
82
What are the six steps by which TB infection occurs?
``` Inhalation Inflammatory cells bacterial dissemination dendritic cell presentation immune system cells granulomas ```
83
What happens during the inhalation stage of TB infection?
Infection initiated by the inhalation of aerosol droplets that contain bacteria
84
Where are inflammatory cells recruited to during a TB infection?
to the lung
85
Where does bacterial dissemination occur?
disseminates to the draining lymph node
86
What happens after the bacterial dissemination stage?
the dendritic cell presentation of bacterial antigens
87
What happens after the bacterial antigen stage?
leads to T cell priming and triggers an expansion of antigen-specific T cells, which are recruited to the lung.
88
Which cells are recruited in a TB infection?
T cells B cells activated macrophages other leukocytes
89
What leads to the establishment of granulomas?
immune cells being recruited to the lungs
90
What do granulomas contain?
Mycobacterium tuberculosis
91
Where are the droplets containing TB bacteria deposited after entering the body?
in terminal airspaces in the lungs
92
What is the role of the alveolar macrophages?
they ingest bacilli in the terminal airspaces of the lungs | they recruit more macrophages
93
How are the TB bacteria able to survive once ingested by the macrophages?
they are able to replicate within the endosome of the macrophages so they survive inside them rather than being killed off
94
After ingestion by macrophage, where are the TB bacteria transported to?
the regional lymph nodes
95
What could happen to the TB bacteria in the regional lymph nodes?
they might be killed off entirely | they might be walled off in granulomas
96
How does granuloma formation occur?
the TB bacteria in the regional lymph nodes trigger T cell priming and an expansion of antigen specific T cells which are recruited to the lungs the activated macrophages establish granulomas, which then wall off any remaining bacilli
97
Is granuloma formation an effective immune strategy for protecting from TB?
yes - this contains the infection in about 90% of individuals
98
What happens to TB bacteria inside granulomas?
might become calcified and completely killed off in the granulomas - infection eradicated might start multiplying and become primary TB might control it - have live but dormant mycobacteria within an active granuloma
99
What are the consequences for a patient with dormant mycobacteria within a granuloma?
patient is asymptomatic at a later stage, it might reactivate and disseminate this occurs in about 10% of individuals
100
What are the features of latent TB?
Dormant bacilli Contained by host defences Non-infectious Asymptomatic
101
What are the features of active TB?
Actively replicating bacilli May be infectious (site-dependent) Symptomatic (site-dependent)
102
How can active TB be diagnosed?
by isolating acid fast bacilli by growing Mycobacterium tuberculosis by demonstrating its presence by conducting a PCR and finding the presence of the MTB genome in the sample
103
How can latent TB be diagnosed?
by demonstrating the hosts' immune response
104
What are the aims for managing TB?
cure active disease reduce spread prevent reactivation
105
How is TB managed?
prompt and adequate treatment; | appropriate source isolation by contact tracing
106
What types of infections are commonly caused by gram negative bacteria?
pneumonia, bloodstream infections wound or surgical site infections meningitis in healthcare settings
107
Are Gram-negative bacteria easily treatable?
no bc they are resistant to multiple drugs and are increasingly resistant to most available antibiotics
108
What does a Gram stain test involve?
Gram stain test, these organisms yield a positive result. a chemical dye which stains Gram +ve bacteria cell walls purple and Gram -ve bact pink, as their cell walls don't hold the dye

M103 T4 (19 decks)

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