Respiratory tract infections

Question 1

URTIs

Answer 1

sinusitis
pharyngitis
laryngitis
tracheitis

Question 2

upper airway obstruction

Answer 2

acute onset (usually):
croup (laryngotracheobronchitis)
epiglottitis
neck abscess (e.g. peritonsillar, retro-pharyngeal)
syphilitic gumma (soft, non-cancerous growth resulting from tertiary syphilis)

slow onset (usually):
enlarged tonsils or adenoids

unlikely to produce significant obstruction:
TB
fungal infections

Question 3

typical pneumonia

Answer 3

high fever
tachycardia
pleuritic pain
severe SOB
painful cough, rusty sputum
CXR: lobar or broncho-pneumonia
strep pneumoniae, staph aureus

Question 4

atypical pneumonia

Answer 4

fever often moderate
relative bradycardia
usually no pleurisy
consolidation variable
cough may be late, often no sputum, rarely haemoptysis
Mycoplasma pneumoniae
Chlamydophila ( Chlamydia) pneumoniae
Legionnaires disease ( Legionella pneumophila)
Respiratory viruses, including the following:
Influenza A and B
Rhinovirus
Respiratory syncytial virus
Human metapneumovirus

Question 5

mycoplasma pnuemoniae

Answer 5

epidemics every 4y, lasting for <1y
extrapulmonary features:
diarrhoea, vomiting, abdo pain, abnormal LFT, otalgia, pharyngitis
myalgia
pericarditis, myocarditis
haemolytic anaemia (cold agglutinins - high volumes of antibodies, usually IgM, directed against erythrocytes)
erythema multiforme

Question 6

nosocomial pneumonia

Answer 6

oropharyngeal colonisation common - pseudomonas
predispositions - antacids, ABx, biofilms
ventilator associated - pseudomonas aeruginosa, staph aureus

Question 7

clinical diagnosis of pneumonia

Answer 7

in absence of CXR:

1. cough, 1 or more LRTI Sx, fever
2. new focal signs O/E
3. no other explanation for illness

with CXR:

1. cough, 1 or more LRTI Sx, fever
2. new radiographic infiltrates
3. no other explanation for illness

Question 8

CURB-65

Answer 8

Confusion
Urea >7mmol/l
Resp rate >29
BP < 60mmHg diastolic, or < 90mmHg systolic
age > 65

for severity also consider hypoxaemia (<8kPa/<90%),
involvement of 2 lobes and any pre-existing disease

Question 9

Tx of pneumonia

Answer 9

oxygen
ABx
analgesics
consider ITU

Question 10

ABx therapy for pneumonia

Answer 10

for CAP, cover pneumococcus and atypical pathogens:
amoxicillin and clarithromycin
for severe use piperacillin-tazobactam
fro suspected staphylococcus add flucloxacillin
for nosocomial use pip-taz

Question 11

acute bronchitis or bronchiolitis

Answer 11

common
cough, usually sputum, orten upper airway Sx
no consolidation on CXR
usually viral, seldom needs admission

Question 12

infective exacerbation of COPD

Answer 12

increased volume or change on the character of sputum
increased freq and severity of cough
increased dyspnoea
CXR usually unchanged

Question 13

bronchiectasis

Answer 13

irreversible dilation of the proximal medium-sized bronchi
poor tracheobronchial clearance
chronic airways infection

Question 14

associations with bronchiectasis

Answer 14

CF
immunodeficiency, esp. hypogammaglobulinaemia
rheumatological disease esp. RA
IBD, esp. UC
bronchial obstruction and infection esp. TB

Question 15

lung abscess associations

Answer 15

pulmonary infarction, malignancy, tumour
pneumonia - staph, klebsiella, strep pyogenes
patients who are unconscious or who are undergoing anaesthesia
pre-hospital vomiting while drunk
haematogenous spread - endocarditis, septic phlebitis

Question 16

diagnosis of lung abscess

Answer 16

may present after pneumonia
commonly non-specific, weight loss, fever
later on, fingers may show clubbing
sputum cultures may be unreliable

Question 17

Tx of abscess

Answer 17

ABx for 8 weeks or longer (choice depends on suspected cause)
usually start with broad spectrum
ABx will not cure the abscess

Question 18

empyema

Answer 18

pus in pleural space
40% of bacterial pneumonias have effusion
9% of pneumonia in hospitalised patients will lead to empyema
spread of infection from lungs to mediastinum
exudative effusion: protein >30g/l, pH <7.20
1 year mortality up to 20%

Question 19

Tx of empyema

Answer 19

if pus or pH <7.20, insert chest drain

ABx will not cure empyema

Question 20

influenza

Answer 20

1918 ‘swine flu’ A/H1N1 killedn >25m people in 6/12
severe pneumonia - primary influenzal, secondary strep/staph
encephalitis lethargica

Question 21

influenza virus

Answer 21

RNA virus from the family Orthomyxovirus
types A & B pathogenic for humans
epidemics chiefly type A

Question 22

antigenic variation of influenza

Answer 22

antigenic drift: RNA replication is error prone

Question 23

influenza Tx

Answer 23

oseltamivir (tamiflu)
zanamivir (relenza)
amantidine

prevention: annual immunisation for:
over 65
chronic resp disease
heart disease
renal failure
cancer
DM
immunosuppression
nursing homes
etc

Question 24

TB

Answer 24

mycobacterium tuberculosis (M bovis, M africanum)
symbiosis lasts many years (sometimes whole lifetime)
converging evolutionary interests of the parasite and host 
intracellular parasite, replicates inside phagocytes

9.4 m active TB tb each year (55% in asia)
1.3m deaths a year
highest rates in the UK amongst indians, paki, bangladeshi
a disease of poverty and people who are hard to reach

Question 25

cycle of TB

Answer 25

exposure leads to infection (not in everyone)
of these, 95% will develop latent TB, 5-10% of which will end up with secondary (active) TB (reactivation or reinfection)
the other 5% will develop primary TB, which either resolves or becomes latent TB`

Question 26

clinical presentations of TB

Answer 26

primary vs post-primary (reactivated) TB
most clinical manifestations are due to host response, not the actual bacteria

lungs are the main site of primary TB infection
reactivated TB in manly at the lung apices
at first, non-specific Sx: weight loss, fatigue, night sweats
tissue necrosis, cavitation, enlargement of tubercles (bones)
cough, haemoptysis, SOB, chest pain occur late
now the patient becomes infectious
later on–> bronchiectasis and fibrosis

in the 15% of extrapulmonary TB:
lymph nodes, pleura, skeletal, meningeal, pericardial, miliary
more likely in immunosuppressed e.g. HIV

Question 27

diagnosis of TB

Answer 27

CXR
histology - caseating granuloma
microscopy and culture (usually sputum) for definitive diagnosis
contact tracing (NB compulsorily notifiable)
for latent TB skin testing, IGRA

Question 28

IGRA - interferon-gamma release assays

Answer 28

quantiFERON-TB gold, T-spot.TB
sensitivity is better than skin tests, though not enough to rule out TB
IGRA often negative in active TB
cannot distinguish between latent and active TB
false positives may occur with other bacteria

Question 29

screening for TB

Answer 29

london has the highest rates in western europe
10% are drug resistant. increasingly MDR-TB
cough >4 weeks ? have you been street homeless
screening tests: PPD (mantoux) + IGRA

Question 30

latent TB

Answer 30

1-2 billion worldwide (mostly sub-saharan africa and south asia)
55% increase in UK between 1993-2010
immune response keeps mycobacteria inside a granuloma so they cannot be detected directly
immune control may be weakened later by immunosuppression e.r under nutrition, HIV, prednisolone
10-15% lifetime chance of progression to active disease (>50% within 5 years of initial infection in children)

Question 31

diagnosis of latent TB

Answer 31

no active TB on CXR, exam or bacteriology
AND
mantoux >6mm without BCG
OR 
IGRA positive with or without BCG

Question 32

microscopy for TB

Answer 32

sputum or other specimen (bronchial lavage, CSF; gastric washings in children)
at least 3 sputa
stain (usually ziehl-neelsen (acid fast stain) or auramine)
‘smear positive’ means alcohol and acid fast bacteria seen in sputum (e.g. mycobacteria, not necessarily in M TB)

Question 33

Tx of TB - RIPE

Answer 33

initial phase:
Rifampicin (hepatotoxic)
Isoniazid (hepato & neuro toxic)
Pyrazinamide (hepatotoxic)
Ethambutol (neurotoxic, esp. to retina, colour vision is the first to deteriorate)

continuation phase:
rifampicin and isoniazid for 4 months (10 months in meningitis or spinal infection)

Question 34

Tx of latent TB

Answer 34

treat in HIV or healthcare worker and >66y
rifampicin and isoniazid for 3 months
OR
isoniazid or rifampicin for 6 months

Question 35

immunoprophylaxis of TB

Answer 35

bacillus calmette-guerin
neonatal BCG in UK for baby at high risk
offers some protection against severe TB
unreliable in adolescents
not for HIV infected as it is a live vaccine

Question 36

non-TB mycobacteria (NTM)

Answer 36

environmental saprophytes in soil and water
thrive in chlorinated water, concentrated by heating
not transmitted person-person
clinical features determined by interaction with host

Question 37

pulmonary NTM infection

Answer 37

diagnosis is difficult because the cultures can be false positive and false negative in non-cavitating infection

pulmonary NTM infection is increasing, mostly M avium, M kansasii and M malmoense

various manifestations e.g cavitation, bronchiectasis, nodules or masses, hypersensitivity pneumonia

Question 38

Tx NTN infection

Answer 38

only treat if causing deterioration
NTM often drug resistant
usually requires multiple ABx
surgery may be more effective (esp. in M abscessus)

Question 39

leprosy

Answer 39

mycobacterium leprae, very slow growing
mostly in india, brazil, indonesia, bangladesh. nigeria
mostly resp acquisition
early diagnosis and Tx prevent disability

spectrum of disease from tuberculoid (TL, paucibacillary) in people with strong immune defences to lepromatous (LL, multibacillary) in those with weak immunity

Question 40

leprosy manifestations

Answer 40

skin: sparse hypoaesthetic maculkes in TL (tuberculoid leprosy) or multiple nodules full of bacilli in LL (lepromatous leprosy)

neuropathy (localised in TL, generalised in LL)