Respiratory Tract Infections Flashcards
What are some URTIs (2)
Sinusitis
Tonsilitis
What are some LRTIs (5)
Bronchitis Pneumonia Empyema Bronchiectasis Lung Abscess
What are some respiratory pathologies that make a patient more prone to infection (5)
Poor swallow (CVA, muscle weakness, alcohol) Abnormal ciliary function (smoking, viral infection, Kartagner's) Abnormal mucus (CF) Dilated airways (bronchiectasis) Defects in host immunity (HIV, immunosuppression)
18 year old woman c/o fever, cough, malaise
Diagnosed with flu by GP. No Abx
Attended A + E
Temp 38 º C
Sats 87% OA
RR 24
Chest- clear Bloods: WCC 40.8, Neut 36.3, CRP 63
CT showed densely consolidated and collapsed left lower lobe
What is the most likely organism?
Streptococcus pneumoniae
What type of bacteria is streptococcus pneumoniae
Gram positive cocci
What proportion of CAP is caused by streptococcus pneumoniae
30-50%
What are the clinical signs of a strep pneumoniae infection (3)
Severe pneumonia
Fever, rigors
Lobar consolidation
What is the most effective antibiotic for strep pneumoniae
Almost always penicillin sensitive
What is pneumonia
Inflammation of the lung alveoli
What is the mortality associated with pneumonia
5-10%
What percentage of CAP are admitted to hospital
20-40%
What is the presentation of pneumonia (6)
Fever Cough +/- sputum. Pleuritic chest pain Shortness of breath Rigors. Malaise, nausea and vomiting.
There are often localising signs and an abnormal CXR
How is pneumonia classified (2)
Community-acquired
Hospital-acquired
What is the most common cause of hospital acquired pneumonia
Ventilator associated
What are some underlying factors that predispose to pneumonia (4)
Pre-existing lung disease
immuno-compromise
Geography, seasons, epidemics
Travel, exposure to animals
What are the main organisms responsible for CAP (5)
Streptococcus pneumoniae Haemophilus influenzae Moraxella catarrhalis Staphylococcus aureus Klebsiella pneumoniae
What organisms cause pneumonia in 0-3months of age (3)
E.coli.
Group B Streptococcus
Listeria
What organisms cause pneumonia in 1-6monhs age (3)
Chlamydia trachomatis
Staphylococcus aureus
RSV
What organisms cause pneumonia in 6months-5 years (2)
Mycoplasma
Influenza
What organisms cause pneumonia in 16-30 years (2)
Mycoplasma pneumoniae
Streptococcus pneumoniae
What are most CAP
Typical 85%
Atypical 15%
What organisms cause typical CAP (2)
Streptococcus pneumoniae.
Haemophilus influenzae.
What organisms cause atypical CAP (4)
Legionella
Mycoplasma (epidemincs 4-6 years)
Coxiella burnetii (Q fever)
Chlamydia psittaci (psittacosis)
What are some risk factors for Q fever pneumonia (Coxiella burnetii) (3)
Present worldwide
Farm animals
Hepatitis
What increases risk of psittacosis
Exposure to birds
What are some features of psittacosis (3)
Splenomegaly
Rash
haemolytic anaemia
What are the clinical SIGNS of pneumonia (7)
Pyrexia Tachycardia Tachypnoea Cyanosis Dullness to percussion, tactile vocal fremitus Bronchial breathing Crackles
What investigations are indicated in pneumonia (7)
FBC, U&E, CRP
Bacterial cultures, Sputum MC&S
CXR
What is the CURB65 score used for
Used to determine if a CAP requires hospitalisation
What are the components of the CURB65 score (5)
Confusion Urea >7mmol/L RR >30 BP <90S, >60D >65 years
What CURB65 score warrants hospital admission
Score 2 = ?admit
Score 2-5 = mange as severe
What is bronchitis
Inflammation of medium sized airways
Who is prone to bronchitis
Smokers
What are the symptoms of bronchitis (4)
Cough
Fever
Increased sputum production
Increased shortness of breath.
What can you see on a CXR in bronchitis
Nothing - normal CXR
What organisms can cause bronchitis (4)
Viruses
S.pneumoniae
H.influenzae.
M.caterrhalis
How is bronchitis managed (3)
Bronchodilation
Physiotherapy
+/- antibiotics.
56 year old man Flu-like illness Presented with cough and fever Blood-stained sputum Pyrexial Not severely unwell Cavitation of CXR
Haemophilus influenzae
What is haemophilus influenz
Gram negative coccobacillus
What proportion of CAP is due to h.influenzae
15-35%
Who is most at risk of h.influenzae pneumonia
More common in those with pre-existing lung disease
What must be noted with treating h.influenzae CAP
May produce beta-lactamase
62 year old man Presented with SOB Family also reported recent confusion Smoker Satn 91% air Chest examination normal Na 124 CXR shows bilateral interstitial changes
Legionella pneumophilia
How do you acquire legionella CAP
Inhalation of infected water droplets
What is the major complication of legionella pneumonia
Can cause multi-organ failure
What culture is required to detect legionella pneumonia
Buffered charcoal yeast extract
What is atypical pneumonia
Pneumonia caused by organisms without a cell wall
What are some organisms which can cause atypical pneumonia (4)
Mycoplasma
Legionella
Chlamydia
Coxiella
What antibiotics cannot be used in atypical pneumonias
Cell-wall active antibiotics do not work (e.g. penicilllins)
What sort of antibiotics are needed in atypical pneumonias
Agents that work on protein synthesis
What are some antibiotic classes that work on protein synthesis (2)
Macrolides
Tetracyclines
Name two macrolides (2)
Clarithromycin
Erythromycin
Name a tetracyclin
Doxycyclin
What are some extra-pulmonary features of atypical pneumonias (2)
Hepatitis
Low sodium
What proportion of CAPs are atypical
20%
What are two key clinical features of atypical pneumonias (2)
Flu-like prodrome before fever and pneumonia
Extra-pulmonary complications
How is legionella pneumonia spread
Aerosol spread
Confusion, abdominal pain, diarrhoea are associated with…..
Legionella pneumophilia
How is legionella pneumophilia diagnosed
Antigen in urine/serum
What is the best antibiotic for legionella pneumonia
Macrolides (e.g. clarithromycin/erythromycin)
How is coxiella burnetti transmitted (2)
Common in domestic/farm animals
Transmitted by aerosol or milk
How is coxiella burnetii diagnosed
Serology
What is the best antibiotic class to treat coxiella burnetti
Macrolides
How is chlamydia psittaci spread
Spread from birds by inhalation
How is chlamydia psittaci diagnoised
Serology
What is the best antibiotic class for the treatmetn of chlamydia psittaci
Macrolides
74 year old woman
Presented with SOB, fever and right sided pleuritic chest pain
PMH: IHD, CABG, AF
DH: Warfarin
Otherwise well
Examination: T 38.5oC
Reduced persussion note and decreased air entry right base.
Admitted, commenced on cefuroxime and doxycycline. Continued to spike fevers.
Empyema
What are some causes why someone with pneumonia may not improve despite being on adequate treatment (6)
Empyema/abscess Proximal obstruction (tumour) Resistant organism (TB) Not receiving/absorbing antibiotics Immunosuppression Other diagnosis (lung cancer, cryptogenic organising pneumonia)
21 year old male From Ecuador Presented with cough, weight loss U and E normal Hb 10.4 WC 9.8 LØ 1.1 HIV neg CRP 173 Alb 31 CXR shows RUZ shadowing
Tuberculosis
What are some clues for TB as a diagnosis of pneumonia (5)
Ethnicity Prolonged prodrome Fevers Weight loss Haemoptysis
What is the classical appearance of TB on CXR
Upper lobe cavitation (but can vary considerably)
How long does a patient have to have been in hospital to diagnose then with hospital acquired pneumonia
> 48 hours in hospital required before diagnosis can be made
What are some factors that predispose to hospital acquired pneumonia (2)
Often previous antibiotics
Ventilator
What is the desired investigation in suspected hospital acquired pneumonia
Bronchial lavage desirable to differentiate upper respiratory from lower respiratory flora
What are the three most common causes of hospital acquired pneumonia (3)
Enterobacteriaciae - 31%
Staphylococcus aureas - 19%
Pseudomonas spp - 17%
64 year old retired general Treated for lymph node Tb Increasing SOB over one month Non-productive cough Chest examination: normal CXR: bilateral ground glass shadowing
Pneumocystis carinii
What causes pneumocystis carinii
Protozoan
What are the clinical features of pneumocystis carinii (5)
Insidious onset Dry cough Weight loss Shortness of breath Malaise
What is the classical appearance of pneumocystis carinii on CXR
Bat’s wings
How is pneumocystis carinii diagnosed
Immunoflouresence of bronchio-alveolar lavage
What is the treatment for pneumocystis carinii
Septrin (co-trimoxazole)
How can pneumocystis carinii be avoided
Prophylaxis septrin
22 year old man
Chemotherapy for leukaemia
Prolonged neutropenia (<1.0)
Ongoing fevers and raised inflammatory markers
Abx: Meropenem, ciprofloxacin, vancomycin, Tazocin, gancyclovir
Interstial changes on CT
Aspergillus fumigatus
What are the three forms of aspergillus fumigatus in the lung (3)
Allergic bronchopulmonary aspergillosis
Aspergilloma
Invasive aspergillosis
How does allergic bronchopulmonary aspergillosis present (3)
Chronic wheeze, eosinophilia, bronchiectasis
How does aspergilloma present (2)
Fungal ball often in pre-existing cavity.
May cause haemoptysis.
Who is at risk of invasive aspergillosis
The immunocompromised
What is the treatment for invasive aspergillosis
Amphotericin B
What LRTIs are HIV patients at risk of (3)
PCP
TB
Atypical mycobacteria
What is the causative organism:
Neutropenia
Immunocompromised
Fungi (e.g. aspergillus spp)
What is the causative organism of pneumonia in a patient who has had a bone marrow transplant
CMV
What is the causative organism in a patient who has had a splenectomy
Encapsulated organisms (e.g. s.pneumoniae, h.influenzae, malaria)
What must be sent before commencing antibiotic treatment in a patient presenting with pneumonia (2)
Sputum/induced sputum
Blood cultures
What organisms can be detected with a urinary antigen test (2)
S.pneumoniae
Legionella pneumophilia
When should you send for a urinary antigen in CAP
If it is very severe
What is the use of antibody tests (4)
Only useful on paired serum samples
Usually collected on presentation and 10-14 days later
Look for rise in antibody level over time
Most useful for organisms that are difficult to culture (e.g. chlamydia, legionella)
When is immunoflouresence used (4)
Antibody labelled with fluorescent dye
Technique often used in Virology
PCP – Pneumocystis carinii (now renamed P. jiroveci) immunofluorescence is the only common IF test used in microbiology laboratories
May also be detected by Silver stain in cytology lab
What antibiotics are effective in gram +ve organisms (5)
Amoxycillin Flucloxacillin Co-amoxiclav=augmentin Cefuroxime Vancomycin
What antibiotics are effective in gram -ve organisms (4)
Ciprofloxacin
Ceftazidime
Gentamicin
meropenem or piperacillin + taxobactam
What antibiotics are effective against atypical organisms (2)
Clarithromycin/doxycycline
What antibiotics are usually used in mild-moderate CAP (2)
Amoxicillin
or erythromycin/clarithromycin
What antibiotics are usually used in moderate-severe CAP (2)
Needing hospital admission: augmentin (co-amoxiclav) and clarithromycin
Allergic: cefuroxime and clarithromycin
What is first line in treating hospital acquired pneumonia (2)
Ciprofloxacin +/- vancomycin
What is second line/ITU for treatment of hospital acquired pneumonia (2)
Piptazobactam and vancomycin
What is used to treat MRSA hospital acquired pneumonia
Vancomycin
What is used to treat pseudomonas hospital acquired pneumonia (2)
Piptazobactam or ciprofloxacin +/- gentamicin
21 year old man No past medical history Smoker Drinker Presented with cough and SOB Satn 89% on air Hypotensive
How would you treat this patient?
Treated with cef and clarithromycin
Fluid resuscitation (hypotensive)
Supplemental oxygen
Senior support requested
How can you prevent pneumonia (2)
Smoking advice
Vaccination (childhood - immunisation schedule; adults: influenza annually, pneumovax every 5 year)