Respiratory Tract Infections

Name 5 Upper respiratory tract infections (URTI)

• Sinusitis / rhinitis

• Otitis media

• Pharyngitis

• Tonsillitis

• Epiglottitis

Name 3 Lower respiratory tract infections (LRTI)

• Tracheitis / bronchitis

• Bronchiolitis

• Pneumonia / pneumonitis

Are viral/bacterial resp tract infections more common

Viral

VIRAL = cough, coryza, hoarse, myalgias, diarrhoeas, rashes, others sick

BACTERIAL = more severe, fever, not resolving

What’s the proper name for the common cold

Rhinosinusitis

Rhinosinusitis normal incubation period

1-3 days

Rhinosinusitis duration of symptoms

1-2 weeks

3 drug “classes” that give symptomatic relief for rhinosinusitis

Paracetamol, NSAIDs, antihistamines

6 possible viral causes of Rhinosinusitis

◦ Rhinoviruses

◦ Coronaviruses

◦ Adenoviruses

◦ Parainfluenza viruses; respiratory syncytial viruses

(could also be Influenza viruses or SARS-CoV-2)

What other symptoms may appear if sinusitis becomes bacterial

Sometimes superimposed bacterial infection (acute bacterial sinusitis) → sneezing, nasal discharge (sometimes purulent), headache, facial pain, etc.

What 3 things would lead you to suspect there is a bacterial infection with sinusitis

◦ No improvement or worsening after 8-10d

◦ High fever, significant facial pain

◦ Development of central nervous system features (emergency)

2 possible bacteria in sinusitis

◦ Streptococcus pneumoniae

◦ Haemophilus influenzae

Otitis media is what

Ear infection/inflammation

Otitis media is usually viral/bacterial (& give example of most likely cause)

Viral - Rhinovirus

Occasionally, Otitis media has a secondary bacterial infection caused by what 3 bacteria

◦ Streptococcus pneumoniae

◦ Haemophilus influenzae

◦ Moraxella catarrhalis

3 most common causes of Pharyngitis (2 viral, 1 bacterial)

◦ Glandular fever (Epstein-Barr virus); HIV

◦ B-haemolytic Streptococcus (eg. S. pyogenes)

Name 3 other bacteria that could cause Pharyngitis

Mycoplasma, anaerobes, Corynebacterium diphtheriae

Clinical scores may be helpful in determining the need for antimicrobial therapy.

What 4 points/symptoms are used to decide whether someone gets treated for strep

Acute epiglottitis is usually caused by what (be specific)

H. influenzae type b

Acute epiglottitis clinical presentation

Toxic, dysphagia, drooling of saliva

What 3 precautions must be taken with Acute epiglottitis treatment?

◦ Get specialist review (eg. ENT) promptly

◦ Secure airway; avoid unnecessary examination

◦ Early antibiotics

Give an example of an antibiotic you could use for Acute epiglottitis

Ceftriaxone

Now moving to Lower respiratory tract infections…

What’s another name for Laryngo-trachea-bronchitis

Croup

Croup is most often seen in which age group

Typically in younger children (< 6 yrs)

Croup symptoms

Characterised by a barking-type cough, hoarseness of voice, fever, agitation, stridor, etc

Croup is usually caused by what

Parainfluenza viruses

(Occasionally RSV)

Bronchiolitis is seen most in what age group

Typically in infants and young children

Bronchiolitis is seen most at what time of year

winter

Bronchiolitis is usually caused by what bacteria/virus

Usually caused by respiratory syncytial viruses (RSVs)

Symptoms of Bronchiolitis

Wheezing, cough, URTI symptoms

Proper name for whooping cough

Pertussis

Pertussis is caused by what bacteria/virus

Bordetella pertussis

Morbidity and mortality of pertussis is highest in what age group

Highest in infants

Symptoms of the Catarrhal stage (early stage - most infectious) of pertussis

Coughing spasms (wks-mths) characteristic inspiratory whoop in children; infants may develop apnoea and cyanosis; complications of pneumonia & encephalopathy, etc

What is treatment for pertussis

Early Rx (with macrolides) can reduce infectivity and duration of symptoms

True/False Immunity received after Pertussis lasts a lifetime

False - Immunity wanes over time (>10 yrs)

When might a booster vaccination be indicated for pertussis (2)

Pregnancy

Certain HCWs

Symptoms of Community-acquired pneumonia

cough, purulent sputum, dyspnoea, chest pain, fever, anorexia, sweats, etc.

What 2 viruses/bacteria generally cause community-acquired pneumonia

Streptococcus pneumoniae

Haemophilus influenzae (non-type b)

Name 4 atypical organisms that could cause community-acquired pneumonia

Legionella pneumophila; Mycoplasma pneumoniae; Chlamydophila pneumoniae; Coxiella burnetti (Q fever)

Name 3 viruses that could cause community-acquired pneumonia

Influenza viruses

SARS-CoV-1 / SARS-CoV-2

MERS-CoV

2 examples of Pneumonic complications of systemic viral infections

Measles, Varicella-zoster (chickenpox)

Name 4 other possible bacterial causes of community-acquired pneumonia

Staphylococcus aureus

Pseudomonas aeruginosa

Anaerobes

Klebsiella pneumoniae

When might you suspect Staphylococcus aureus as a cause for community-acquired pneumonia

Post-trauma or post-influenza

When might you suspect Pseudomonas aeruginosa as a cause for community-acquired pneumonia

cystic fibrosis

bronchiectasis

How would Anaerobes enter your system to cause community-acquired pneumonia

Aspirated

2 possible fungal causes of community-acquired pneumonia

Pneumocystis, Aspergillus

Which possible fungal cause of community-acquired pneumonia would only be seen in severely immuno-compromised patients

Aspergillus

True/False Mycobacterium tuberculosis could be a cause of community-acquired pneumonia

True

Streptococcus pneumoniae (major pathogen for community-acquired pneumonia) is gram +/- and what shape

Gram-positive diplococci

Risk groups for invasive pneumococcal disease (IPD)

• Age

• Co-morbidities

>65 yrs or <2 yrs

Chronic lung, cardiovascular, renal and liver diseases

Diabetes mellitus, alcohol abuse

Asplenia/hyposplenism

Immunosuppression (condition and/or treatment)

Post-influenza (secondary bacterial infection)

Streptococcus pneumoniae causes what type of pneumonia: Bronchopneumonia, Aspiration pneumonia, Lobar pneumonia

Lobar pneumonia

What can Streptococcus pneumoniae be treated with

Varying levels of susceptibility to penicillin

True/False Higher doses of penicillin/amoxicillin can overcome intermediate penicillin susceptibility in S. pneumoniae

True

What is co-amoxiclav a combo of

amoxicillin & clavulanic acid

Is co-amoxiclav (amoxicillin-clavulanate) superior to amoxicillin if S. pneumoniae is susceptible to both?

No — if Streptococcus pneumoniae is susceptible to amoxicillin, there is no benefit in using co-amoxiclav over amoxicillin alone

When should co-amoxiclav (amoxicillin + clavulanic acid) be used?

Amoxicillin alone can be broken down by β-lactamase enzymes produced by some bacteria

Clavulanic acid inhibits β-lactamase, protecting amoxicillin

Main indications: infections where β-lactamase–producing bacteria are likely. E.g. Haemophilus influenzae & Moraxella catarrhalis

Give 4 classes of drug treatments for S. pneumoniae RTI

Beta-lactams

Macrolides

Quinolones

Tetracyclines

Give 2 types of Beta-lactams used in the treatment of S. pneumoniae RTI (& give an example of each)

Penicillins (eg. penicillin, amoxicillin)

Cephalosporins (eg. ceftriaxone)

Give 2 examples of Macrolides used in the treatment of S. pneumoniae RTI

clarithromycin, erythromycin

Give an example of a Quinolone used in the treatment of S. pneumoniae RTI

levofloxacin

Give 2 examples of Tetracyclines used in the treatment of S. pneumoniae RTI

tetracycline, doxycycline

‘Atypical’ bacterial pathogens present slightly differently. How would symptoms differ

May have more prominent extra-pulmonary features eg. CNS, gastrointestinal, etc.

How would lab testing differ for ‘atypical’ bacterial pathogens

They don’t grow on standard media eg. blood agar; alternative methods of diagnosis

How would radiological features differ for ‘atypical’ bacterial pathogens

Perihilar infiltrates

Diffuse infiltrates, etc.

How would treatment differ for ‘atypical’ bacterial pathogens

Beta-lactams are ineffective; often requires Rx with macrolides or fluoroquinolones

What Investigations would you carry out for pneumonia

Clinical history and physical examination

Radiological eg. Chest X-ray

General laboratory: FBC, biochemistry, ESR, CRP, blood gas

Microbiological:

◦ Sputum for microscopy, culture, etc.

◦ Nasopharyngeal swab (PCR for eg. viruses)

◦ Blood culture

◦ Urine

Others: eg. bronchoscopy, biopsy

In investigation of pneumonia, what are you testing for in urine

Legionella & pneumococcal antigens

In investigation of pneumonia what culture medium is generally used

Usually on blood and chocolate agar

How is it decided if hospitalisation is necessary for pneumonia

CURB-65 criteria

Explain the CURB-65 criteria

What CURB65 score is considered Mild/Moderate/Severe CAP (Community-acquired pneumonia)

What CAP scored require admission

2+

How is mild CAP treated

How is moderate CAP treated

How is severe CAP treated

Fill in the antibiotics used in the treatment of CAP

How does treatment change for S. pneumoniae vs H. influenzae/M. catarrhalis vs Atypical organisms

S. pneumoniae: often responds to high-dose penicillin/amoxicillin

H. influenzae/M. catarrhalis: β-lactamase-producer? → consider amoxicillin-clavulanic acid

Atypical organisms: Macrolides or quinolones

How does treatment change for mild vs moderate-severe cases

Mild cases:

◦ Amoxicillin / Amoxicillin-clavulanic acid Or

◦ Clarithromycin Or

◦ Doxycycline

Moderate to severe cases:

◦ Amoxicillin plus clarithromycin; Or

◦ Amoxicillin / Amoxicillin-clavulanic acid plus clarithromycin; Or

◦ Cefotaxime plus clarithromycin

Top 3 causal organisms of typical pneumonia

. Streptococcus pneumoniae

· Haemophilus influenzae

· Staphylococcus aureus

Top 3 causal organisms of atypical pneumonia

· Mycoplasma pneumoniae

· Chlamydia pneumoniae

· Legionella pneumophila

Which group of Legionella pneumophila causes the majority of legionellosis

Serogroup 1

Symptoms of Legionella infection

fever, cough, altered mental status, abdominal symptoms, headaches, hyponatraemia, elevated liver enzymes, etc.

3 groups @ high-risk for legionellosis

◦ Elderly patients

◦ Heavy smokers, chronic lung disease

◦ Steroids, other causes of immunosuppression

How is Legionella pneumophila usually acquired (transmitted)

Usually acquired via inhalation of aerosolised organisms after exposure to environmental sources eg. contaminated air-conditioning systems, Jacuzzis, cooling towers, etc.

How is Legionella pneumophila diagnosed

Difficult to culture (needs special medium)

Look for Legionella urine antigen (L. pneumophila serogroup 1)

PCR assay for respiratory samples

Treatment for Legionella pneumophila

Quinolones (eg. levofloxacin)

or

Macrolides (eg. clarithromycin, erythromycin)

Now we’re moving to Hospital-acquired pneumonia. What is the most common causal organism

Staphylococcus aureus (including MRSA)

Name 3 bacteria that could cause Hospital-acquired pneumonia

E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa

Do gram +/- bacteria cause Hospital-acquired pneumonia

Gram -

Infective exacerbation of COPD can be a cause of pneumonia. How would you spot this?

Acute change of symptoms beyond baseline levels:

Eg.

Change in purulence of sputum

Increase in sputum volume

Increase in dyspnoea

True/False Infective exacerbation of COPD would show consolidation on imaging

False - no consolidation

Most common bacterial causes of Infective exacerbation of COPD

Haemophilus influenzae (non-type b)

Streptococcus pneumoniae

Moraxella catarrhalis

What would be a bacteria that would cause an advanced disease Infective exacerbation of COPD

Pseudomonas aeruginosa

Main viral cause of Infective exacerbation of COPD

Rhinoviruses

Are there any other possible viral causes of an Infective exacerbation of COPD

Influenza and Parainfluenza viruses; RSV; others

Rx in infective exacerbation of COPD

Most guidelines recommend:

Beta-lactam (eg. amoxicillin or amoxicillin-clavulanate)

Or

Macrolide (eg. clarithromycin)

Or

Tetracycline (eg. doxycycline)

Influenza virus is a DNA/RNA virus

RNA

How many types of Influenza virus are there

3 types: A, B, C