Respiratory Infection Flashcards
What are signs and symptoms of upper respiratory tract infection?
cough sneezing runny or stuffy nose sore throat headache
What are signs and symptoms of lower respiratory tract infection?
productive cough muscle aches wheezing breathlessness fever fatigue
What are signs and symptoms of pneumonia?
chest pain
blue tinting of the lips
severe fatigue
high fever
Are acute respiratory infections one of the top ten global causes of death?
yes
What is DALY?
Disability-adjusted Life Year
A sum of Years of Life Lost (YLL) and Years Lost to Disability (YLP)
As age increases, what happens to rates of pneumonia?
increase
What are common causative agents of bacterial respiratory infection?
Streptococcus pneumoniae
Myxoplasma pneumoniae
Haemophilus Influenzae
Mycobacterium tuberculosis
What are common causative agents of viral respiratory infection?
Influenza A or B virus Respiratory Syncytial Virus Human metapneumovirus Human rhinovirus Coronavirus
List different ways of acquiring pneumonia
community acquired
hospital acquired
ventilator acquired
List examples of pathogens that usually cause community acquired pneumonia.
Streptococcus pneumoniae (40-50%) Myxoplasma pneumoniae Staphylococcus aureus Chlamydia pneumoniae Haemophilus Influenzae
List examples of pathogens that usually cause hospital acquired pneumonia.
Staphylococcus aureus Psuedomonas aeruginosa Klebsiella species E. Coli Acinetobacter spp. Enterobacter spp.
List examples of pathogens that usually cause ventilator acquired pneumonia.
Pseudomonas aeruginosa (25%) Staphylococcus aureus(20%) Enterobacter
Briefly outline mechanisms of damage of pneumonia.
lung injury > arterial hypoxemia > ARDS
bacteremia, systemic inflammation, treatment > organ infection > sepsis
What is supportive therapy/treatment for bacterial pneumonia?
hypoxia > oxygen
dehydration > fluids
pain > analgesia
nebulised saline may help expectoration
What types of antibiotics should you give to treat bacterial pneumonia? Give examples.
penicillins e.g. amoxicillin
macrolides e.g. clarithromycin
Briefly describe how penicillins work.
beta lactams that bind proteins in the bacterial cell wall to prevent transpeptidation
Briefly describe how macrolides work.
bind to the bacterial ribosome to prevent protein synthesis
What is the key to increasing the success of antibiotics?
time to administration
using an effective AB (typical CAPs may respond to penicillins, atypical CAPs require macrolides)
Define microbiota.
Ecological communities of microbes found inside multi-cellular organisms
Define commensal.
Microbes that live in a “symbiotic” relationship with their host
Define opportunistic pathogen.
A microbe that takes advantage of a change in conditions (often immuno-suppression)
Define pathobiont.
microbe that is normally commensal, but if found in the wrong environment (e.g. anatomical site) can cause pathology.
Give an example of an opportunistic pathogen.
mycobacterium tuberculosis
Risk factors for active TB?
HIV
alcohol
smoking
Standard treatment for TB
requires a combination of 4 antibiotics for a 6 month period
It’s estimated that what % of the population has latent TB?
25%
Define serotypes.
distinct variation within a species of bacteria or virus or among immune cells of different individuals
viruses which cannot be recognized by serum (antibodies) that recognize another – implications for protective immunity
Why do viral infections result in disease?
cellular inflammation
mediator release
damage to epithelium > loss of cilia, loss of chemoreceptors, poor barrier to antigens, bacterial growth
Aetiology of human rhinovirus
Major group bind ICAM-1
Minor group low density lipoprotein family of receptors
Aetiology of H1N1 influenza A
Haemogglutinin binds 𝛂2,6 sialic acids
Aetiology of H5N1 avian flu
Haemogglutinin binds 𝛂2,3 sialic acids
Aetiology of SARS -CoV-2
Spike (S) protein binds Angiotensin converting enzyme 2 (ACE2)
Aetiology of respiratory syncytial virus
F and G proteins bind glycosaminoglycans in receptors like IGFR1 and nucleolin
Influenza: reinfection by same strain, yes or no?
no
RSV: reinfection by same strain, yes or no?
yes, recurrent reinfection with similar strains
Why are influenza vaccines imperfect?
vaccine induced immunity rapidly wanes, mainly homotypic immunity, annual vaccination required
Using H1N1 as an example, what causes severe disease?
highly pathogenic strains (zoonotic)
absence of prior immunity
predisposing illness/conditions
What are interferons?
family of cytokines
How are interferons grouped?
3 groups – type I (IFN-αs/IFN-βs), type II (IFN-γ), type III (IFN-λ)
What immune cells provide long term protection after vaccination and natural infection?
B cells
What is the leading cause of infant hospitalization in the developed world?
RSV bronchiolitis
Risk factors for RSV bronchiolitis in children?
premature birth
congenital heart and lung disease
Signs and symptoms of RSV bronchiolitis?
nasal flaring
hypoxemia and cyanosis
croupy cough
expiratory wheezing, prolonged expiration, rales and rhonchi, chest wall retractions, tachypnea with apneic episodes
Describe the age dependance of RSV.
infant > RSV bronchiolitis
young child* > postbronchiolitic wheeze
child/adult* > exacerbation of asthma/COPD
elderly* > insidious respiratory illness
*colds due to (re)infection
Treatment options for RSV
vaccines
monoclonal antibodies
anti-virals
How many serotypes of RSV?
2
A, B
