Respiratory Tract Infections Flashcards
1
Q
what is the main problem with respiratory tract infections?
A
secondary infections
2
Q
how is the nasopharynx adapted for respiratory tract infections?
A
very adapted with innate and adaptive immunity to prevent infection
Saliva - absorb virus particles and bacteria, as well as having antimicrobial peptides present
Alveolar macrophages
Virus are very common and change rapidly so don’t develop immunity - hence why colds/coughs common
3
Q
issue with viruses and host immunity
A
Virus are very common and change rapidly so don’t develop immunity - hence why colds/coughs common
4
Q
3 most common upper respiratory tract infections
A
sinusitis (rhinosinusitis)
tonsilitis
pharygitis
5
Q
sinusitis (rhinosinusitis)
A
inflammation of sinuses
nice environment for bacteria to grow
6
Q
pharyngitis
A
red swollen throat
7
Q
best way to treat upper respiratory tract infections
A
gargle with salt water or chlorohexidine
generally don’t need antibiotic
8
Q
what type of infection are most URT infections?
A
viral
9
Q
key bacteria that can infect URT
A
streptococcis pyogens
bordatalla pertusis
10
Q
what % aetiology is viral for Tonsillitis/Pharyngitis?
A
70
11
Q
what viruses can cause Tonsillitis/Pharyngitis?
A
rhinovirus (common cold)
adenovirus
parainflluenza
others
12
Q
what causes glandular fever?
A
Epstein Barr Virus
13
Q
what does Epstein Barr glandular fever effect?
A
Effects lymph nodes, out of work for up to 6 months potentially
14
Q
how does a viral particle progress in the body
A
- Virus attached to epithelia
- Gets inside the cells
- Divides rapidly
- Causes cell to self-destruct
- Virus shedding
- Macrophages may come along to tidy things up
- Disrupt viral membranes
If unchecked bacteria can take over
Fundamentally should recover in short period of time
15
Q
what does the viral particle induce in the host?
A
physiological response
chemical mediators of inflammation –> vascular dilation –> nasal obstruction
increased vascular permeability –> serum transudation —> rhinorrhea
sensitisation and irritation of airways receptors –> cholinergic stimulation –> bronchoconstriction —> cough
16
Q
what causes 25% of sore throats?
A
S.pyogens (group A)
resides in nasopharynx
17
Q
what % of children are asymptotic carriers of S.pyogens (group A)?
A
15-20%
18
Q
what is a pathogenic virus?
A
Viral strain adapted to causing disease e.g. S.pyogens (group A)
19
Q
what is a cariogenic organism
A
S.mutans
20
Q
whats dies Group A Strep Pyogens produces as Virulence factors?
A
- pyrogenic exotoxins
- streptolysins
- hyaluronidase
- M protein
21
Q
what do exotoxins made by Strep Pyogens do?
A
Exotoxins break up cell membranes, blood cells and collagen fibres
22
Q
what do M proteins made by Strep Pyogens do?
A
Surrounds the organism
Prevents desiccation
23
Q
potential M protein secondary effects
A
M protein looks like self-protein
- antibody response to M protein
Attack cardiac tissue
- rheumatic fever (caused by antigens), myocarditis
24
Q
possible complications of streptococcal sore throat
A
- peri-tonsillar abscess
- ottis media or sinusitis
- scarlet fever (less common)
- rheumatic fever
- rheumatic heart disease
- acute glomerulonephritis
25
rheumatic fever
indirect complication of streptococcal sore throat
antibodies to antigens in streptococcal cell wall cross-react with the sarcolemma of human heart
26
rheumatic heart disease
repeated attacks of streptococcus pyogenes infection can result in damage to heart valves
future attacks prevented by penicillin prophylaxis in childhood
27
asthma
```
upper airways affected
fairly common
- Airways decrease
- Mucous build ups - plugs
- Cough to try and remove the mucous
- Smoke and allergies can stimulate asthma
```
All culminate to cause bronchitis
28
bronchitis
inflammation of the tracheobronchial tree
29
acute bronchitis occurs when
usually during winter months
most often viral infection
30
chronic bronchitis is
Productive cough on most days during at least 3 months in each of 2 successive years.
- Affects 10-25% of population.
Predisposing = Smoking, infection, air pollution & allergies
Viral & bacterial agents
31
chronic bronchitis affects
10-25% of population
32
causes of chronic bronchitis
Predisposing = Smoking, infection, air pollution & allergies
Viral & bacterial agents
33
virus Vs bacteria upper respiratory infection causes
virus 90%
| bacteria 10%
34
common viral infections of upper respiratory tract
- rhinovirus
- Influenza
- adenovirus
35
common bacteria infections of upper respiratory tract
- Bordatella pertussis
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Haemophilus influenzae
36
Bordatella pertussis of upper respiratory tract
hooping cough, can be fatal
- Cough till sick
- Produces an exotoxin - stimulate the upper bronchi
- Lots of energy needed, may need incubated and hospitalised
37
treatment of upper respiratory tract infections
Decongestants, salt water gargle, NSAIDs, antibiotics where appropriate
Antibiotics if infection doesn’t clear
- Bacterial infection not viral
38
prevalence of mycobacterium tuberculosis infection
New infection every second
1/3 of entire global population infected
- 1% of population infected every year
3 million deaths per year (lot unnecessarily)
- 8 Million symptomatic
Causes 25% of preventable deaths
Most pre-eminent fatal disease l Predicted by 2020:
- 1 billion infected, 200 Million, 35 Million Deaths
Ability of people to global travel means quick spread from hot spots (Africa, India, Pakistan)
Many are asymptomatic but carriers - risk
39
why is mycobacterium tuberculosis infection so wide spread?
Ability of people to global travel means quick spread from hot spots (Africa, India, Pakistan)
Many are asymptomatic but carriers - risk
40
why is mycobacterium tuberculosis successful at spreading?
lipid outer cell wall which protects it
- Macrophages engulf but cannot do anything
- Grows inside and then grows out of it
- Builds tubercle in lung (ball)
(Can be latent for many years)
- But if immune system low, will grow again
- Become liquid and get into lungs (systemic spread) and spread via cough
- Causes body to shut down and die
41
treatment and prevention of mycobacterium tuberculosis
Triple therapy - streptomycin, para-aminosalicylic acid & isoniazid
- 3 different antibiotics, twice a day for 6 months (costly)
- Long term
DOTS – Directly Observed Treatment Short course
- Microscopy services
- Drug supplies
- Surveillance
- Political commitment
- Monitoring systems
95% cure rate
Prevents transmission
42
what is a common difficulty in treatment of respiratory tract infections?
hard to diagnose
Bacterial or viral? Hard to tell as symptoms are similar
43
transmission of TB
inhalation of aerosolised respiratory droplet nuclei from infected person with active pulmonary TB
- low infectivity among casual contacts
- higher infectivity among long-term contacts especially in crowded conditions or closed air environments
44
high risk factors for TB
- close contact with known active TB case
- residency in prison or health care facilities
- HIV infection
- injection drug abuse
- alcoholism
- contact with persons from high prevalence TB countries (Africa, Asia, Latin America)
45
symptoms of TB
```
malaise
productive cough for more than 3 weeks
headache, fever
weight loss, night sweats
blood in sputum
```
46
diagnosis of TB
- acid-fast bacilli in sputum
- isolation of mycobacterium tuberculosis from sputum
- skin testing (tuberculin testing) with purified protein derivative to determine infection
- chest radiograph
47
preventive therapy of TB
BCG vaccine
48
pneumonia
an inflammatory condition of the lung – especially affecting the microscopic air sacs (alveoli)
49
what typically causes pneumonia?
Typically caused by an infections, but multi- factorial
| - Bacteria, viruses, fungi and parasites (often combination)
50
what do most people die of?
pneumonia
Tipped over the edge
- Cancer, care homes, hospitalised
- Lungs less efficient - infection deep in lungs can no longer cope
51
clinical features of pneumonia
- Sudden or insidious onset
- Fever, rigors, malaise
- Shortness of breath, rapid shallow breathing, cyanosis
- Cough producing purulent sputum
- Consolidation of lungs on clinical and radiographic examination
flu like
generally need hospitalised
52
causes of community acquired pneumonia
Streptococcus pneumonia
Viruses
- Mycoplasma pneumonia
- Haemophilus influenzae
- Legionella pneumophila
- Chlamydia pneumonia
- Moraxella (branhamella) catarrhalis
- Pneumocystis carinii
53
causes of hospital acquired pneumonia
Esp if incubated standard oral care not as good as it should be
- Mouth is source of infection
- Staphylococcus aureus
- Gram-negative bacilli e.g. pseudomonas spp.
- Klebsiella pneumoniae
- Escherichia coli
- Legionella pneumophila
54
what is the main causative agent in bacterial pneumonia?
streptococcus pneumonia
55
how is likely to be affected by streptococcus pneumonia?
```
Affect young (children and neonates), elderly and immuno-compromised
- Less now due to vaccine
```
56
cases and mortality rate of adult pneumococcal pneumonia
50,000 cases of adult pneumococcal pneumonia/year - 9000 fatalities per year (21% mortality rate)
57
under 5 pneumococcal pneumonia infection rate
1 in 200 UK’s under 5’s admitted with pneumococcal pneumonia
58
what type of infection in streptococcus pneumonia?
Encapsulated Bacterial Infection
- Cause infection as good at avoiding immune system
Capsule surrounds things
- Can’t be seen by complement
- Immune system become frustrated
- Organisms of inflammatory nature = gram positive more
59
how is streptococcus pneumonia adapted to infect people?
encapsulated
pneumolysin binds to tissue and can be free in solution and can bind to Fc portion of antibody
has adhesins
- pneumococcal surface protein
- pneumococcal surface adhesin
- surface protein A
- choline binding protein A
60
clinical management of pneumonia
Antibiotics (iv), plus hospitalization?
- beta-lactams, erthyromycin, quinolones
- Pre-antibiotic era – 35% mortality
- Resistance
Vaccination
- Based on 23 different serotypes
- Polysaccharide antigens ineffective at promoting memory – T-cell independent
- Conjugate vaccines of polysaccharides and proteins appear efficaceous, with proper clinical intervention
61
increasing issue with pneumonia treatment
Antibiotic therapy is increasingly ineffective due to increasing resistance of isolates (beta-lactams, erthyromycin, quinolones)
- Better to prevent than treat
Take key proteins to make multivalent vaccine
But, deal with one organisms but other organisms take over their place to cause pneumonia
- they adapt faster than we develop
62
concern with hospital and dental chair water supplies and lines
bacteria biofilm can grow easily
- aerosolise when use hand-piece = spread
can cause Legionnaire's disease
- Inhalation of aerosols from contaminated water
- Aspiration of oropharyngeal colonised bacteria
dental chairs have their own water supply - replace daily
hospital water supply is hard to be completely sterile
63
legionnaire's disease symptoms
Initially flue like symptoms which progress to a sever pneumonia
- Sometimes confusion, renal failure and GI symptoms
64
legionnaire's disease diagnosis
- Culture and identification or demonstration in tissue or body fluids by immunofluorescence or DNA probes
- Measurement of antibody levels
- Chest radiographs
65
legionnaire's disease diagnosis
- Erythromycin is drug of choice
| Unresponsive to penicillin
66
hospital associated pneumonia
Incubated - tube has potential to transmit as organisms can attach and spread into lungs, can die
Think of oral cavity for vulnerable cared for individual
- Toothbrushing, chlorhexidine - often overlooked but can prevent infection
67
case mortality for Legionnaire's disease
- 5% in treated patients
- 20-30% in untreated otherwise healthy patients
- 24% in treat immunocompromised patients
- 80% in untreated immunocompromised patients
68
dentures as sources of respiratory tract infections
Patients often do not remove their dentures
- Microorganisms attach to denture
- Harbour more than their natural teeth
Aspiration pneumonia risk
69
influenza characteristics
- Types A, B, C
- Diameter 80 - 120 nm
- Pleiomorphic, spherical, filamentous particles
- Single-stranded RNA
- Segmented genome, 8 segments in A and B
- Hemagglutinin and Neuraminidase on surface of virion
70
classification of influenza
Classified on the basis of hemagglutinin (HA) and neuraminidase (NA)
15 subtypes of HA and 9 subtypes of NA are known to exist in animals (HA 1-15, NA 1-9)
3 subtypes of HA (1-3) and 2 subtypes of NA (1-2) are human influenza viruses. HA 5, 7, 9 and NA 7 can also infect humans
complex
71
method of influenza infection
virus adsorbs to a respiratory epithelial cell by hemaglutinin spikes and fuses with the membrane
the virus is endocytosed into a vacuole and uncoated to release its B nucleocapsid segments into the cytoplasm
nucelocapsids are transported into the nucleus. There the (-) RNA strand transcribed into a (+) strand that will be translated into viral proteins that make up the capsid and spikes
(+) RNA is used to sythesise glycoprotein spikes inserted into the host membrane
(+) RNA strands are used to synthesis new (-) RNA strands. These are assembled into nucleocapsids and transported out of the nucleus to the cell membrane
Release of mature virus occurs when viral parts gather at the cell membrane and are budded off with an envelope containing spikes
72
source of influenza infection
patients and carriers.
73
mode of influenza transmission in humans
aerosol
| - 100,000 TO 1,000,000 VIRIONS PER DROPLET
74
common aerosol transmission of influenza virus
large droplets (sneezing, coughing, contact with saliva)
75
probably common influenza transmission
- contact
- direct
- fomite
76
rare influenza transmission
- airborne over long distance
77
incubation for influenza
18-72 hours
78
symptoms of influenza
Central
– headache
Systemic
– fever (usually high)
Muscular
– (extreme) tiredness
Joints
– aches
Nasopharynx
– runny/stuffy nose; sore throat; aches
Respiratory
– coughing
Gastric
– vomiting
79
prophylaxis for influenza
Masks
- Effectiveness not shown for influenza
- However, could reduce transmission associated with large droplets
Handwashing
Generally perceived to be useful (No studies specifically performed for influenza)
Easy to recommend
80
immunoprophylaxis with vaccine
```
Inactivated:
(1) whole-virus
(2) subvirion
(3) purified surface antigen
(Only subvirion or purified antigen should be used in children. Any of the three can be used for adults)
```
Live attenuated:
81
free influenza vaccine recipients
Women in 2nd or 3rd trimester of pregnancy during flu season.
Household members of persons in high-risk groups
Health care workers and others providing essential community services.
82
antivirals for influenza
Adamantanes and neurominidase inhibitors
83
epidemic
The occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular period of time*.
84
pandemic
An epidemic occurring over a very wide area (several countries or continents) and usually affecting a large proportion of the population.
Examples:
- Cholera
- AIDS
- Pandemic Influenza
85
antigenic variation
Influenza viruses tend to undergo changes from time to time.
Changes in the antigenic characteristics of influenza viruses determine the extent and severity of influenza epidemics
There are two types of changes:
- antigenic shift
- antigenic drift
86
2 types of antigenic variation
antigenic shift
antigenic drift
87
antigenic drift
denotes MINOR changes in hemagglutinin and neuraminidase of influenza virus
results from mutation in the RNA segments coding for either the HA or NA
involves no change in serotype; there is merely an alteration in amino acid sequence of HA or NA leading to change in antigenicity.
88
what causes antigenic drift
results from mutation in the RNA segments coding for either the HA or NA
89
what is the consequence of antigenic drift
involves no change in serotype;
there is merely an alteration in amino acid sequence of HA or NA leading to change in antigenicity.
90
antigenic shift
denotes MAJOR changes in hemagglutinin and neuraminidase resulting from reassortment of gene segments involving two different influenza viruses
When this occurs, worldwide epidemics may be the consequence since the entire population is susceptible to the virus
91
consequence of antigenic shift
worldwide epidemics may be the consequence since the entire population is susceptible to the virus
92
1918 flu pandemic
May have killed as many people as the Black Death- bubonic plague
- The majority of deaths were from a secondary infection such as bacterial pneumonia
It killed between 2 and 20% of those infected; normal mortality rate is 0.1%
It mostly killed young adults with more than half of the deaths in people between 20 - 40 years old due to novel surface proteins on the virus.
It killed as many as 25 million in the first 25 weeks, whereas HIV/AIDS has killed 25 million in the first 25 years.
