-
what are the main differences between the upper and lower respiratory tract? (sterility, morbidity, mortality, cause)
- URTI: non sterile, high morbidity, low mortality, viral
- LRTI: sterile, high morbidity, high mortality, bacterial
-
what are the 2 main viral causes of rhinitis? and what type of viruses are they?
- rhinovirus: small RNA virus
- coronavirus: RNA virus
-
what is the pathogenesis of rhinitis?
infection/inflammation of nasal mucosa
-
what are the symptoms of rhinitis?
itchy eyes, blocked nose, sore throat, cough,
-
what is the main presentation of pharyngitis?
sore throat
-
what is the most common cause of pharyngitis? give e.g.
virus: influenza, parainfluenza, EBV, HSV, Coxsackie A
-
what is the most important bacterial cause of pharyngitis?
group A streptococcus=strep progenies
-
what are the other bacterial causes of pharyngitis?
- haemophilus influenzae
- Group C and G Streptococci
- rarely Corynebacterium diphtheriae
-
how would you differentiate a bacterial sore throat from a viral?
- spiking temperature
- pus
- higher severity: barely swallow
- necrosis (white patches)
-
if you suspect bacterial pharyngitis what investigation needs to be done and why is it good and what is the immediate treatment and what needs to be avoided?
- bacterial THROAT SWAB as S.pyogenes grows overnight as beta-haemolytic clones on blood agar
- Rx: start penicillin for 10 days
- avoid: amoxicillin as if it is EBV - you can get a rash due to cross reaction between abx and virus
-
why do you treat GAS so aggressively?
- to prevent the immunological sequelae:
- acute glomerulonephritis
- rheumatic fever
- these happen due to immune mimicry: Ab against GAS cross react and bind to glomerular BM or cardiac membrane
-
why do some people with bacterial pharyngitis go red? what happens around eye?
- GAS makes an erythrogenic toxin which makes you go red = scarlet fever
- circumoral pallor: around eyes still white!
-
what is the test for glandular fever?
monospot or EBV antibody detection
-
what does acute otitis media and sinusitis usually follow?
viral UTRI
-
why is AOM more in children under 5?
short eustachian tube
-
name 3 of the most common causes of AOM and acute sinusitis?
- Strep pneumo
- Haem influenzaue
- Moraxella catarrhalis
- i.e. from URT normal flora track via ET
- GAS
-
what are the Rx options for AOM?
- watch and wait
- antimicrobials: amoxicillin
-
what are 3 Rx options of acute sinusitis:
- douching
- anti microbials
- surgical drainage
-
how does acute epiglottitis present?
stridor, drooling, sore throat, high fever
-
why is acute epiglottitis an emergency?
swelling may threaten airway
-
what USED to be the most common cause of acute epiglottitis and why is it no longer?
Haemophilus influenza b (now Hib vaccine)
-
what is now the most common cause of acute epiglottitis?
group A strep = strep progenies
-
what is the Ix and Rx of acute epiglottitis?
- Ix: do NOT examine mouth as may precipitate acute resp obstruction
- treat: high dose iv cefotaxime
-
what is whooping cough?
- bacterial illness: bordetella pertussis
- laryngotracheitis
-
what are the 3 clinical stages of pertussis?
- prodrome
- catarrhal
- paroxysmal whooping stage
-
how do you diagnose pertussis?
pernasal swab onto spcecial charcoal media or PCR
-
what is the treatment of pertussis and for how long?
- erythromycin for 3 weeks
- penicillin resistant
-
what do we do to prevent pertussis?
acellular vaccination at 2, 3, 5 months and pre-school booster at 3-5years
-
what is croup? and how does it present?
- laryngotracheobronchitis
- fever, barking inspiratory noises, cough, hoarseness
-
what is the most common causes of croup?
viral: infleunza and parainfluenza
-
what are the symptoms of influenza?
- sudden onset, fever, malaise, headache, myalgia, non productive cough, sore throat
- last 4-7days
-
what type of virus is influenza? (2 marks)
- orthomyxovirus
- RNA virus with segmented genome
-
what does the envelope of influenza contain?
- haemagglutinin (HA)
- neuraminidase (NA) proteins
-
what are the different types of influenza?
- A: epidemics and pandemics
- B: milder disease, pandemics
- C: not pathogenic in man
-
what is the difference between epidemic and pandemic?
- epidemic: out of control in one nation
- pandemic: out of control in more than 3 countries in the world
-
what time of the year does influenza outbreak?
winter
-
what is the incubation period of influenza?
1-4 days
-
how does influenza spread as epidemics and pandemics?
- antigenic change in HA and NA
- shift: major change
- drift: minor change
-
what are the complications of influenza?
- primary influenza pneumonia (rare, often fatal - pregnant women)
- secondary bacterial pneumonia - causes death. infected with Staph aureus, pneumo, h.influ
-
how do you make a lab diagnosis of influenza?
- nasopharyngeal secretions or nose/throat swabs and do:
- viral culture, PCR, antigen detection by immunofluorescence
-
why is serology useless in most diagnosis?
retrospective so limited value. when get results, illness over!
-
how is influenza prevented? 3 ways from simple to complex
- 1. hand washing, disinfecting surfaces and use of masks to stop you touching your mouth
- 2. oseltamivir (NA inhib): use for post exposure prophylaxis
- 3. inactivated (killed) vaccine with current strains of influenza A and B
-
who is influenza vaccine given to?
- over 65 yo
- healthcare workers
- chronic illness: renal failure, heart probs, respiratory disease, liver disease, immunosuppressed
-
what is the treatment of influenza? and how does it work?
- oseltamivir or zanamivir both neuraminidase inhibitors give as soon as symptoms start
- they limit viral shedding
-
what type of virus is parainfluenza?
- paramyxovirus
- RNA
- 4 serotypes, 4 lower pathogenicity
-
what is the Rx of parainf?
Rx not usually indicated
-
which are the normal flora of the URT that cause LRTI?
- strep pneumoniae
- haemophilus influenzae
- moraxells catarrhalis
- staph aureus
-
why do normal flora of the URT cause LRTI?
reduced host defences
-
how are some bact/viruses transmitted?
droplet spread
-
how is coxiella burnetti spread?
transmitted via contact with animals/animal products
-
how is legionella pneumophila spread?
aerosolised contaminated water supplies
-
name 9 host defences:
- nasopharyngeal infiltration
- mucosal adherence
- lysozyme, protease, lactoferrin present in respiratory secretions
- mucociliary escalator
- cough and gag reflex
- immunoglobulins: IgA in nasal mucosa
- complement
- T and B lymphocytes
- alveolar macrophages
-
name 5 groups of patients that have reduced host defence and explain why door each one:
- ventilated patients: bypassed nasopharyngeal filtration, bypassed gag and cough reflex, reduced mucociliary clearance
- smokers: mucosal adherence is not as effective, mucociliary function impaired
- cystic fibrosis
- asplenic
- COPD
-
what are Strep pneumo and h.infl's virulence factors?
- produce IgA protease: disable mucosal IgA
- polysaccharide capsules: resistant to phagocytosis
-
what is Bordatella pertussis' virulence factor?
makes endotoxins - widespread local damage
-
what is the main pathogen for bronchiolotis?
RSV: respiratory syncytial virus
-
who is most affected by bronchiolotis?
infants esp. in first 6 months of life
-
what type of virus is RSV and how many serotypes?
-
how is RSV spread?
droplet spread or contact with fomites
-
why do you have to end diagnose RSV?
source isolation
-
how is RSV diagnosed?
- throat swab, nasopharyngeal aspirate into viral CULTURE
- viral antigen detected using IMMUNOFLUORESCENCE
-
how is RSV bronchiolitis managed?
- admit if severe LRTI
- supportive Rx: oxygen thearpy
- Ribavarin by AEROSOL inhalation or severe
- source isolation
- hand washing: prevent nosocomial transmission
-
what is used to prevent RSV in high risk infants?
- monoclonal RSV Ab vaccine: palivizumab
- in prewinter season to high risk babies. but £
-
what is the definition of pneumonia
inflammation of lung parenchyma caused by infection usually
-
what is the definition of community acquired pneumonia
presenting in community or within 48 hours of attending hospital
-
what are the 4 typical causes of bacterial CAP?
- strep pneumonia
- haemophilus influenzae
- moraxella catarrhalis
- staph aureus
- all give lobar pneumonia (typical)
-
what are 4 causes of atypical bacterial CAP?
- Mycoplasma pneumoniae
- Legionella pneumophila
- Chlamydia
- Coxiella burnetti: Q fever - rare - contact with animal product - vets
-
what is the leading cause of CAP in under 2yo?
RSV
-
name 3 viral causes of CAP and who does it affect?
- influenza
- parainfluenza
- human metapneumovirus
- elderly and immunocompromised most at risk
-
what are the symptoms and signs of TYPICAL pneumonia?
- fever
- productive cough
- breathlessness
- purulent sputum
- haemoptysis
- pleuritic chest pain
- shallow rapid breathing
- reduced chest movements
- dull to percussion
- bronchial breathing with COARSE crepitations
-
what type of bacteria is strep pneumo?
gram positive diplococcus
-
how does strep pneumo grow on blood agar?
ALPHA haemolysis
-
what is strep pneumo the LEADING CAUSE OF?
- CAP
- AOM
- acute sinusitis
- acute exacerbations of COPD
-
how is strep pneumo diagnosed?
- CULTURE: blood or sputum
- antigen detection on URINE dipstick
-
what is the empirical treatment of typical CAP? give mild, mod sev
- mild-mod: amoxicillin
- severe: benzyl-penicillin plus clarithromycin OR cefurozime and clarithomycin
-
what is the presentation of ATYPICAL pneumonia?
- fever
- confusion
- non productive cough
- myalgia
- headache
-
what are the CXR signs of atypical pneumonia?
patchy consolidation
-
what are the CXR signs of typical pneumonia?
lobar consolidation
-
who does legionella pneumophila commonly affect?
middle aged males
-
what time of year does legionella come about?
- summer months - related to travel - hotels with dodgy AC or water supply
- need exposure to CONTAMINATED WATER - showers, AC, sprays
-
how is legionella diagnosed?
- antigen in urine
- culture of respiratory secretions
-
what is the treatment of legionella pneumophila?
- macrolide: clarythromycin
- and rifampicin if severe (orange urine)
-
do patients with legionella pneumonia need to be source isolated?
no because it doesn't transmit from person to person
-
what type of year does mycoplasma pneumonia present?
sporadic or epidemic - 4 yearly cycles
-
who does mycoplasma pneumoniae affect?
children and young adults
-
how is mycoplasma pneumonia diagnosed?
- serology
- PCR on resp secretions
-
what is the treatment of mycoplasma pneumonia?
macrolide: clarythromycin
-
what is the definition of hospital acquired pneumonia?
acute pneumonia commencing 48 hours or more after admission to hospital
-
what are the risk factors for HAP?
- time in hospital
- time on ventilation
- NG tube - leading to oropharyngeal (gastric) aspiration
- PPI - inc gastric pH - as suddenly pseudomonas can survive there
- tracheostomy
- chronic pulmonary disease
- severity of underlying disease
-
what organisms cause HAP?
- staph aureus
- pseudomonas aeringosa
- e.coli
- coliforms
- acinetobacter
- respiratory viruses in immunocompromised
-
what are the poor prognostic indicators of pneumonia?
- Confusion
- Urea > 7mmol/l
- Resp rate > 30
- Blood pressure: SBP<90mmHg; DBP<60mmHg
- Age > 65yrs
- NB this score is not good for young people as they are fit, good for older adults
-
what is the empirical treatment for HAP?
broad spec beta lactam: piperacillin-tazobactam (tazocin) this covers coliforms, pseudomonas, staph aureus but not MRSA
-
what is needed in severe HAP?
empirical + gentamicin
-
what is needed to treat MRSA?
glycopeptide: vancomycin
-
what is used in penicillin allergy?
quinolone: ciprofloxacin
-
what is the fast way of detecting Mycobacterium (for TB)?
auramine stain (rather than ZN stain)
-
where is the most common primary infection of TB?
lung
-
name 3 rare sites of primary TB infection
-
what is primary pulmonary TB?
first contact with bacillus
-
what is a ghon complex a combination of?
- initial lesion: small focus of granuloma in parenchyma/subpleural - PERIPHERY of lung
- involvement of draining hilar LN: this is the larger response
-
what do ghon complexes look like macroscopically?
yellow necrotic areas in parenchyma and nodes
-
what is secondary pulmonary TB usually due to? 2 things
- 1. reactivation of primary TB
- only in 5% of primary TB cases
- 2. re-infection - e.g. health care worker
- 3. post BCG
-
where in the lung does primary pulm TB localise to compared to secondary, why?
- primary: periphery
- secondary: apices due to higher PO2 which mycobacterium love
-
what is the pathological sign of secondary pulm TB?
assmann focus - area of necrosis in apices of lung. more extensive parenchymal involvement of upper lobe
-
what are the 4 sequelae of progressive pulmonary TB?
- cavitatory fibrocaseous TB
- bronchopneumonia
- single organ TB
- miliary TB
-
what causes cavitating TB?
- usually secondary TB
- drainage of necrotic tissue into bronchus/bronchiole and formation of cavity
-
what are the conseuences of cavitating TB?
- spread of inflame within lUNGS
- spread into upper airways - then infected sputum swallowed…
- spread to gut
-
what is open TB?
once the TB has spread into the airways
-
what causes TB bronchopneumonia?
dissemination through airways
-
where can Tb spread to via the blood?
- bone - spine - Pott's disease - vertebral collapse and acute angulation of spine
- joints - arthritis
- kidney
- adrenals
- meninges
- GU tract
-
what is miliary TB? and what is it assoc. with?
- WIDESPREAD via blood
- assoc. with reduced immunity
-
where does miliary TB usually spread to?
- lungs
- liver
- spleen
- bone marrow
- i.e. organs with rich blood supply
-
is miliary TB usually seen with primary or secondary TB?
primary
-
what are epitheloid cells?
macrophages that have lost their phagocytic function and so are ineffective in consuming bacteria
-
what are longhan's giant cells?
lots of macrophages (epitheloid cells) joint together to make a multinucleate cell. nuclei arranged in a horseshoe shape
-
name the 4 antiTB drugs and their SE
- rifampicin: orange urine
- isoniazid: hepatitis and peripheral neuropathy (due to depletion of vitB6 so have to give B6 supplements)
- pyrazinamide: hepatotoxicity
- ethambutol: visual disturbance (optic neuritis)
|
|
