Clinical Infections: Respiratory Flashcards
What does the URT consist of?
Nose, sinuses, mouth, pharynx and larynx
What does the LRT consist of?
Trachea, bronchi, bronchioles and lungs
What are the key points in taking a patient history for an acute sore throat?
- Rapidity of onset of sore throat
- Difficulty breathing/speaking
- Ability to eat/drink/swallow
- Associated neck pain/swellings
- Symptoms of systemic infection e.g. fever, chills, rigors, general malaise
- Travel history
What 4 things should immediately be considered when a patient presents with an acute sore throat?
- Pharyngitis
- Acute tonsillar pharyngitis
- Infectious mononucleosis (EBV)
- Epiglottitis
What is pharyngitis?
inflammation of the back of the throat (pharynx), resulting sore throat and fever
How does acute tonsillar pharyngitis?
Symmetrically inflamed tonsils and pharynx (+/- fever +/- headache)
Severe infection: patient has marked systemic symptoms of infection and/or unable to swallow.
How does infectious mono present?
symmetrically inflamed tonsils / soft palate inflammation and posterior cervical lymphadenopathy
How does epiglottitis present?
sudden onset of severe sore throat and fever. Inflammation of the epiglottis and surrounding tissue leading to obstruction of the airway.
How are pharyngitis and tonsillar pharyngitis caused?
Commonly caused by viruses, however in a third of people, no cause can be found.
Are viral or bacterial infections the more common cause of sore throats?
Viral
What are the viral causes of pharyngitis and tonsillar pharyngitis (i.e. sore throat)?
o Rhinovirus o Coronavirus o Parainfluenza o Influenza (A & B) o Adenovirus etc
What is the most common bacterial cause of sore throat?
Group A beta-haemolytic Streptococcus (GABHS) aka Streptococcus pyogenes
What are 3 rarer causes of sore throat?
o Neisseria gonorrhoeae (Gonococcal pharyngitis)
o HIV-1 (can be the first presentation of HIV infection)
o Corynebacterium diphtheriae (Diptheria)
What criteria can help you distinguish if a sore throat is due to a bacterial infection?
Centor criteria
What are the 4 components of Centor criteria?
o Tonsillar exudate
o Tender anterior cervical lymphadenopathy
o Fever over 38°C
o Absence of cough
How can the Centor criteria give an indication of the likelihood of a sore throat being due to bacterial infection?
- If 3 or 4 of Centor criteria are met, the positive predictive value is 40% to 60%
- The absence of 3 or 4 of the Centor criteria has a fairly high negative predictive value of 80% (i.e. non-bacterial infection)
In a patient presenting with a sore throat (but a non-severe infection), when is the only time it would be investigated?
If infectious mononucleosis is suspected
In suspected infectious mononucleosis, what investigation is done to confirm?
blood sample for Monospot or EBV serology
In severe infections of sore throats, what investigations should be done?
o Throat swab for culture
o Blood cultures, (blood tests: full blood count, urea and electrolytes and liver function tests)
Management for majority of sore throats?
Oral analgesics (paracetamol, ibuprofen)
When would you consider antibiotics for a sore throat?
o Consider antibiotics in non-severe acute tonsillar pharyngitis if symptoms present for 1 week and getting worse
o Give antibiotics in severe acute tonsillar pharyngitis, quinsy or epiglottitis
What 3 diseases presenting with a sore throat require antibiotics?
- severe acute tonsillar pharyngitis
- quinsy
- epiglottitis
Viral pathogen behind infectious mono?
EBV (80%) or CMV (20%)
Who does infectious mono tend to affect?
Teenagers, often asymptomatic
Classic triad of symptoms of infectious mono?
1) fever
2) tonsillar pharyngitis
3) cervical lymphadenopathy
Which antibiotic should be avoided in infectious mono?
ampicillin
Why should ampicillin be avoided in infectious mono?
This can result in a maculopapular rash which can then be confused with allergic reaction; patient would then have a FALSE penicillin allergy label
What is epiglottitis?
inflammation of structures above the glottis
What USED to be the commonest cause of epiglottitis?
Haemophilus influenzae type b (Hib) was the commonest cause in >90% of paediatric cases but the Hib vaccine has significantly reduced the rate of Hib epiglottis (still do see Hib cases in adults & rarely in children)
What are other causative organisms of epiglottitis?
Streptococcus pneumoniae and Group A Streptococcus
What investigations should be done in suspected epiglottitis?
Blood cultures and epiglottic swabs
Why should care be taken when taking epiglottic swabs?
Attempting to examine the throat may result in total airway obstruction (only do when anaesthetic support present)
How can epiglottitis lead to death within 24 hours? What is the important factor in management of epiglottitis?
Acute epiglottitis and associated upper airway obstruction have significant morbidity and mortality and may cause respiratory arrest and death within 24 hours.
Securing the airway & oxygenation is a priority!!
Then;
o IV antibiotics (usually 3rd generation cephalosporin)
o Analgesia
If a case of Hib epiglottitis is confirmed, what should be done?
Inform public health
What is the only skin-lined cul-de-sac in the body?
Ear canal
What is otitis externa (OE)?
Inflammation of the external ear canal
What 3 features does OE present with?
- Otalgia (ear pain)
- Pruritus (unpleasant itch)
- Non-mucoid ear discharge
What separates acute from chronic OE?
Symptoms < 3/52 = acute OE
Symptoms >3/52 = chronic OE
What are some risk factors for OE?
o Swimming (or other water exposure)
o Trauma (e.g. ear scratching, cotton swabs)
o Occlusive ear devices (e.g. hearing aids, earphones)
o Allergic contact dermatitis (e.g. due to shampoos, cosmetics)
o Dermatologic conditions (e.g. psoriasis).
Is acute OE typically unilateral or bilateral?
Unilateral
What are the different types of acute OE?
- Mild/moderate/severe
- Necrotising malignant OE
What makes up 90% of causes of acute OE?
Bacterial causes!!
Pseudomonas aeruginosa and Staphylococcus aureus are most common
What makes up only 2% of causes of acute OE?
Fungal causes
Investigations for acute OE?
History and otoscopic examination
Ear swab or pus sample for culture
What additional investigations are required necrotising otitis externa?
- CT temporal bone (and bone biopsy)
- Blood cultures (if systemically unwell)
Non-antimicrobial management for acute OE?
o Remove/modify precipitating factors (e.g. cosmetics, shampoo)
o Remove pus and debris from ear canal
o Analgesia
Antimicrobial management for acute OE?
o Topical agents for mild-moderate
o Topical plus systemic antibiotic such as flucloxacillin for severe AOE
What is malignant necrotising OE?
Occurs when external otitis spreads to the skull base (soft tissue, cartilage, and bone of the temporal region and skull).
Can be life threatening!
Who does malignant necrotising OE typically affect?
Most commonly develops in elderly diabetic or other immunocompromised patients
Symptoms of malignant necrotising OE?
Severe pain, otorrhoea, granulation tissue in the canal floor, and cranial nerve palsies may be present.
Treatment for malignant necrotising OE?
o These patients should be promptly referred ENT
o Treat for a minimum of 6 weeks e.g. with iv ceftazidime then po ciprofloxacin
Is chronic OE typically unilateral or bilateral?
Bilateral
How does chronic OE typically present?
- Pruritus
- Mild discomfort
- Erythematous external canal that is usually devoid of wax
Over time, the external ear canal may become narrowed in chronic OE? Why?
White keratin debris may fill the ear canal and over time the canal wall skin may become thickened narrowing the external ear canal
What are common causes of chronic OE?
o Allergic contact dermatitis (e.g. from chemicals in cosmetics or shampoos).
o Generalised skin conditions such as atopic dermatitis or psoriasis can also predispose to chronic OE
Treatment of chronic OE?
Treat underlying cause
What is otitis media (OM)?
Middle ear inflammation. Fluid present in middle ear.
Who is OM common in?
Children
What defines ‘uncomplicated’ acute OM?
Mild pain <72hours duration, an absence of severe systemic symptoms, with a temperature of less than 39°C and no ear discharge.
What defines ‘complicated’ acute OM?
severe pain, perforated eardrum and/or purulent discharge, bilateral infection, mastoiditis
What are the 3 most common pathogens behind OM?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
Investigations for OM?
Swab any pus
Treatment for OM?
o If not unwell; watch and treat symptomatically (analgesia, decongestant etc.) and review earl
o If unwell; amoxicillin
Which antibiotic is recommended in unwell patients with OM?
Amoxicillin
What is mastoiditis a complication of?
The most common complication of acute OM
What is mastoiditis?
Infection of the mastoid bone and air cells
What significantly reduces the incidence of mastoiditis?
Incidence significantly reduced with the use of antibiotics for OM
How common is mastoiditis?
Very rare;
• Mastoiditis and other severe complications of AOM are very rare in adults
• Occurs in <1 in 1000 children with untreated AOM
Features of mastoiditis?
o Fever
o Posterior ear pain and/or local erythema over the mastoid bone
o Oedema of the pinna
o A posteriorly and downward displaced auricle
What investigation is always required in mastoiditis?
CT scan
Treatment for mastoiditis?
o Analgesia
o IV antibiotics +/-
o Mastoidectomy
Pinna cellulitis vs pericondritis?
Pinna cellulitis can occur as a complication of acute otitis externa, a complication of eczema or psoriasis, or from an insect bite.
Pinna perichondritis is usually a result of penetrating trauma, including ear piercing.
Define cellulitis
inflammation of subcutaneous connective tissue.
Define perichondritis
an infection of the skin and tissue surrounding the cartilage of the outer ear
What is the ‘pinna’?
Outer ear (the only visible part of the ear)
Usual organisms behind Pinna Cellulitis/Perichondritis?
Pseudomonas aeruginosa and/or Staphylococcus aureus
Empirical treatment for Pinna Cellulitis/Perichondritis?
ciprofloxacin + flucloxacillin (or vancomycin if penicillin allergy)
What is pneumonia?
Infection affecting the most distal airways and alveoli. Involves the formation of inflammatory exudate.
What are the 2 anatomical patterns of pneumonia?
- Bronchopneumonia
2. Lobar pneumonia
What is the pattern of bronchopneumonia?
Characteristic patchy distribution centred on inflamed bronchioles & bronchi then subsequent spread to surrounding alveoli
What is the pattern of lobar pneumonia?
Affects a large part, or the entirety of a lobe
Which organism is 90% of all lobar pneumonias due to?
S. pneumoniae
What are the 4 main groups of pneumonia?
1) Community acquired pneumonia (CAP)
2) Hospital acquired pneumonia (HAP)
3) Ventilator acquired pneumonia (VAP)
4) Aspiration pneumonia
What defines ‘hospital acquired pneumonia (HAP)’?
Pneumonia developing >48hrs after hospital admission
Hospital acquired pneumonia (HAP) has additional causative organisms to CAP, especially if >5days after admission.
What are these?
Enterobacteriaceae (e.g. E. coli)
S. aureus (including MRSA)
What is ventilator acquired pneumonia (VAP)?
- Subgroup of HAP
- Pneumonia developing >48hrs after ET intubation & ventilation
- Pseudomonas spp. may be implicated
What is aspiration pneumonia?
Pneumonia resulting from the abnormal entry of fluids e.g. food, drinks, stomach contents, etc. into the lower respiratory tract
(Patient usually has impaired swallow mechanism)
Anaerobes may be implicated
What are the 3 major routes of acquisition of organisms in CAP?
- Person-to-person or from a person’s existing commensals (S.pneumoniae, H.influenzae)
- From the environment (L. pneumophilia)
- From animals (C.psittaci)
The bacterial causes of CAP can be split into 2 main groups. What are they?
Atypical and typical
What is ‘atypical’ pneumonia?
Caused by atypical organisms; clinical presentation and treatment are slightly different
What are 5 ‘typical’ bacteria which cause pneumonia?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
- Staphylococcus aureus
- Klebsiella pneumoniae
What are 5 ‘atypical’ bacteria which cause pneumonia?
- Mycoplasma pneumoniae
- Legionella pneumophilia
- Chlamydophila pneumoniae
- Chlamydophila psittaci
- Coxiella burnetii
Symptoms of bacterial CAP?
Usually rapid onset Fever / chills Productive cough Mucopurulent sputum Pleuritic chest pain General malaise: fatigue, anorexia
Signs of bacterial CAP?
Tachypnoea, tachycardia, hypotension
Examination findings consistent with consolidation:
• Dull to percuss
• Reduced air entry, bronchial breathing
What is atypical pneumonia caused by Chlamydophila psittaci associated with?
Exposure to birds (history!!)
What are outbreaks of Legionella pneumophilia typically associated with?
Colonise water piping systems:
- Showers
- Air conditioning units
- Humidifiers
What score is used to assess the severity of CAP?
CURB-65 score
Explain the CURB-65 score
C: Confusion
U: Urea >7 mmol/l
R: Respiratory rate >30
B: Blood pressure
Age >65
What should the CURB-65 score be used in conjuction with when assessing the severity of a pneumonia case?
Clinical judgement
Why is a chest x-ray not a good measure of an immediate response to pneumonia treatment?
can take 6 weeks+ for radiological changes to resolve
What investigations are recommended for all moderate-severe CAP based on CURB65 score >2?
- Sputum culture
- Blood culture
- Pneumococcal urinary antigen
- Legionella urinary antigen
- PCR or serology
What pathogens are being looked for in PCR or serology in CAP?
- Viral pathogens e.g. influenza or COVID-19
- Mycoplasma pneumoniae
- Chlamydophila sp.
What 2 other tests should be routinely done in CAP?
HIV test
COVID-19 test
Why should an HIV test be performed in CAP?
CAP is an HIV indicator condition; a condition in which the prevalence of undiagnosed HIV is more than 0.1%
Management for all types of pneumonia?
ABC!!
o Airway: Ensure an open, patent and maintained airway
o Breathing:
- Assess respiratory rate and saturations
- Provide supplemental oxygen to reach prescribed target
o Circulation:
- Assess blood pressure and heart rate
- Gain IV access and give IV fluids if haemodynamically unstable
- Urinary catheter to monitor urine output
THEN –> prompt empirical antibiotic therapy
What are 3 potential complications of pneumonia?
- Pleural effusion
- Empyema
- Lung abscess
What viruses typically cause pneumonia?
Adults: Influenza A & B Adenovirus VSV COVID-19
Children:
RSV
Parainfluenza
What viruses typically cause pneumonia in IMMUNOCOMPROMISED hosts?
Normal ones PLUS:
Measles Herpes simplex (HSV) Cytomegalovirus (CMV) Varicella zoster virus (VZV) HHV-6
Typical presentation of influenza infection?
o Fever, headache, myalgia, dry cough, sore throat
o Convalescence takes 2-3 weeks
Usually uncomplicated disease.
Who does primary viral pneumonia occur more commonly in?
In patients with pre-existing cardiac & lung disorders
Symptoms of primary viral pneumonia?
Cough, breathlessness, cyanosis
What can develop post primary viral pneumonia?
Secondary bacterial pneumonia then may develop after initial period of improvement
Which bacteria are largely responsible for secondary bacterial pneumonia?
S.pneumoniae, H.influenzae, S.aureus
What is VSV pneumonia a complication of?
VSV (chickenpox) infection
Who is a significant morbidity and mortality rate of VSV pneumonia seen in?
Adults, immunocompromised, chronic lung disease patients, smokers, pregnant women
Presentation of VSV pneumonia?
Insidious onset 1-6 days after the rash has appeared with symptoms of progressive tachypnoea, dyspnoea, and dry cough.
Treatment of VSV pneumonia?
Supportive and prompt administration of IV acyclovir
Which organism is responsible for most ‘common colds’?
Rhinovirus
Can rhinovirus lead to an LRTI?
Yes
Who can CMV pneumonia cause severe illness in?
o Is rarely described in immunocompetent hosts
o Can cause severe illness in transplant recipients & HIV patients (uncommon)
What should be considered in transplant recipients with CMV pneumonia?
consider immunosuppression reduction
What is bronchiectasis?
Acquired disorder of the major bronchi and bronchioles that is characterised by permanent abnormal dilatation and destruction of bronchial walls
Symptoms of LRTI with bronchiectasis?
o Chronic cough
o Mucopurulent sputum production
o Recurrent infections
Which organisms are responsible for recurrent infections seen in bronchiectasis?
S.aureus, H.influenzea, Pseudomonas aeruginosa, viruses
What investigations should be done during exacerbations of bronchiectasis?
SpO2, CXR, FBC, U&Es, LFTs, CRP, review previous sputum culture
When would antibiotics be required during exacerbations of bronchiectasis?
Antibiotics are recommended for exacerbations with acute deterioration with worsening symptoms
Non-antimicrobial management for LRTI with bronchiectasis?
- Effective clearance of respiratory secretions e.g. physiotherapy, postural drainage
- Nutritional support
- Identification and treatment of underlying cause
- Annual influenza vaccination
What is CF?
An inherited disease caused by a genetic mutation on chromosome 7 resulting in abnormal production and function of the cystic fibrosis transmembrane conductance regulator (CFTR).
The defective CFTR chloride channel function results in viscous secretions.
Which organisms are responsible for infection in CF;
a) in childhood
b) in childhood/early adolescence
a) Staphylococcus aureus
b) Pseudomonas aeruginosa
Which RESISTANT and TRANSMISSIBLE organism can cause LRTI in CF patients?
Burkholderia cepacia complex
General measures for treating LRTIs in CF patients?
o Prolonged antibiotic courses (3-4 weeks not uncommon)
o Postural drainage, deep breathing, coughing, exercise, aerosolised DNAase etc+ Influenza and Pneumococcal vaccinations. Lung transplant.
Which 3 vaccinations are available which can help prevent LRTIs?
1) Pneumococcal vaccination for certain groups (S. pneumoniae)
2) Influenza vaccination for vulnerable groups (annually)
3) COVID-19
What is aspergillosis?
An infection caused by Aspergillus, a common mould (a type of fungus) that lives indoors and outdoors
Who is susceptible to apergilllosis?
o Most people breathe in Aspergillus spores every day without getting sick
o Immunocompromised patients & those with lung disease are at a higher risk of developing health problems due to Aspergillus
Typical health problems caused by Aspergillus?
Include allergic reactions, lung infections, and infections in other organs
Who does Allergic Bronchopulmonary Aspergillosis (ABPA) occur in?
Occurs in people with a background of atopy, asthma & cystic fibrosis
How does ABPA present?
with worsening asthma & lung function
Diagnosis of ABPA?
o A high total IgE, specific IgE to Aspergillus and positive serum IgG Aspergillus
o CT imaging of the thorax may demonstrate central bronchiectasis
Treatment of ABPA?
corticosteroids and antifungal therapy
What is an aspergilloma (pulmonary)?
Mobile mass (of Aspergillus) within a pre-existing lung cavity
Cause of aspergilloma (pulmonary)?
Old cavities left by previous TB or sarcoidosis become colonised with Aspergillus spp.
Symptoms of aspergilloma (pulmonary)?
Cough, haemoptysis, weight loss, wheeze & clubbing. Some are asymptomatic.
Diagnosis of aspergilloma (pulmonary)?
o Can be demonstrated on either chest X-ray or CT thorax
o The diagnosis can be confirmed by a positive test for Aspergillus IgG antibody +/- Aspergillus antigen
o Sputum culture may be positive for Aspergillus spp.
Potential complication of aspergilloma (pulmonary)?
: Massive haemoptysis
What is Pneumocystis pneumonia (PCP)?
A serious infection caused by the fungus Pneumocystis jiroveci.
Transmission of Pneumocystis pneumonia (PCP)?
Airborne
What is a classic finding of Pneumocystis pneumonia (PCP)?
o Reduced exercise tolerance (induced hypoxia)
o Non-productive cough
What is Nocardia Asteroides?
Nocardia is a genus of bacteria found in the environment.
Pulmonary nocardiasis is acquired through inhalation of the organism
Who is pulmonary nocardiasis more common in?
More common in the immunosuppressed and those with pre-existing lung disease (esp. alveolar proteinosis) – but still rare!
Transmission of mycobacterium tuberculosis?
Infection is acquired by inhalation of infected respiratory droplets –> the bacilli lodge in alveoli & multiply
What is a Ghon focus?
A Ghon focus is a primary lesion usually sub-pleural, often in the mid to lower zones, caused by Mycobacterium tuberculosis developed in the lung of a non-immune host.
The risk of disease progression of tuberculosis is highest in which groups?
At the extremes of age and in the immunocompromised (inc. HIV)
Reactivation of TB can occur later in life. Who is this most common in?
Immunocompromised
Presentation of TB?
Pulmonary tuberculosis is the most common presentation:
Chronic productive cough, haemoptysis
Weight loss, fever, night sweats
Can disseminate (miliary TB) or affect almost any other organ
