LTR infections Flashcards
What is the virulencce of LTR pathogens partl dependent on? Name a virulence factor associated with this
Evase of phagocytosis, capsule
Infectious agents enter LTR by?
- Inhaling aerosolised material
- Aspiration of UTR commensals (content of stomach inhaled)
- Haematogenous spread (descending infection, but can be seeded from the blood, usually it’s the other way round)
Community-aquire pneuomonia is split in two types
- Acute lobar pneumonia
- Atypical pneumonia
What is hospital-aquired pneumonia?
- Pneumonia occurring in patients hospitalised for >72 hours
Ventillator-associated pneumonia
- Pneumonia occurring in patients mechanically ventilated for >48 hours
Community aquired bacterial pneumonia in neonates: bacterial causative agents
Group B strep
L. monocytogenes
Community aquired bacterial pneumonia in infants: bacterial causative agents
Encapsulation bacteria (S. pneumoniae, M. pneumoniae, C. pneumoniae
Community aquired bacterial pneumonia in children to young adults: bacterial causative agents
Encapsulation bacteria (S. pneumoniae, M. pneumoniae, C. pneumoniae
Community aquired bacterial pneumonia in older adults: bacterial causative agents
S. pneumoniae.
Legionella spp.
Causative agents of hospital-aquired pneumonia
- P. aeurginosa, other Gram-negative bacilli
Institulionalised pneumonia causative agent
G-ve bacilli, S.aureus MRSA
Pneumonia in CF patients is caused by (3)
P. aeruginosa, Burkholderia cepacia complex, S.aureus
Pneumonia in AIDS pateitns is caused by
Pneumocystis jiiroveci
Lobar pneumonia meaning
Pneumonia affecting the discrete lobe in the lung
Lobar pneumonia is almost always caused by…
Strep. pneumoniae
Why is lobar pneumonia sputum sample difficult?
Goes through mouth
Strep. pneumonia morphology
Gram+ve coccus (lanceolate)
Strep. pneumoniae type haemolysis
Alpha
What is Strep. pneumoniae sensitive to
Optochin
Pathogenicity of Strep. pneumoniae depends on?
Capsule
Brochnopneumonia
Diffuse lung infection
What causes brochnopneuomia
S. aureus
Bronchopneumonia is what degree of infection
Secondary, follows viral infection
Bronchopneumonia sputum looks like ____ and _____
plums and custard
Other bacterial causes of bronchopneumonia
K. pneumoniae, Coliforms and P. aeruginosa.
Necrotising pneumonia is caused by S.arueus producing what
Elaborating Panton-Valentine leukocidin, destroying leukocytes
Legionarraies disease is regarded to as atypical or typical pneumoniae
Atypical
What bacterium caused Legionarraire’s disease, gram stain, shape
Legionella pneumophilia, g-ve, bacillus (poor stain)
Legionarraire’s disease on an x-ray is visualised as what
White out, lung filled with infiltrate
Where is Legionella pneumophilia found, spread through what
Lake, river, ponds, stagnant water. Aerosilation
Symptoms of Legionarraire’s disease
Initially like flu, progress to systemic
Other names for atypical pneumonia
Walking pneumonia, non-cultivable pneumonia
Patients with atypical pneumonia present with what type of cough, symptoms and x-ray visualisation
- Patients present with dry, unproductive coughs
- Fever, myalgia, headache
- Little to no evidence of consolidation on X-ray
Why can’t we use penicillin against atypical pneumoniae
Most bacteria lack cell wall
Bacteria that can cause atypical pneumonia
- Mycoplasma pneumoniae
- Chlamydophila pnemoniae
- Coxiella burnetii (Q fever)
- Chlamydophila psittaci (psittacosis)
What antibiotic is used to treat atypical pneumonia
Erythromycin
How is pneumonia diagnosed in the clinic
- “CURB65” score of severity in CAP:
o Confusion
o Urea >7mmol/L
o Respiratory rate >30/min
o Blood pressure <90mmHg systolic
o Age >65 years - Score 0-1 = Discharge, oral antibiotics, 2 = Observe in hospital ,3-5 = Admission to hospital
- X-ray
- Ultrasound (? Empyema, pus in a cavity, pulmonary empyema, collapse)
Labratory diagnosis of pneumonia
MC&S
Types of sputum to sample
Induced sputum, saline used
Expectorated sputum, wait till patients coughs it up
Contamination, very prone at is travels via UTR
Other choices of sample apart from sputum
- Broncho-alveolar lavage – collect washing
- Blood culture
- Urine (antigen detection)
What bacteria causes Whooping cough: give shape and gram stain
Bordetella pertussis, small G-ve cocco-bacili
How does B. pertussis cause whooping cough
Adheres to trachea and interferes with mucociliary escalator- accumulation of mucus and toxin mediated (PT and AC). Restriction of the airway, narrow.
Key symptom of whooping cough
paroxysmal coughing usually ends in a high-pitched inspiration
Is there a vaccine for whooping cough
yes
Why is B. pertussis difficult to cultivate
Due to inhibitory factors in the lung
What type of toxin is pertussis
AB5 toxin
MOA of pertussis toxin
Causes mass production of cAMP, inhibits inflammatory processes and recruitment of immune system. Evade immune defences.
How many domains does pertussis toxin have
Two. AC domain induces large amounts of cAMP, RTX is a pore former and more toxin inside –> cell death
Wat is pertussis toxin production controlled by
BvgAS, environmental swithc
Respiratory tuberculosis is caused by bacterial species:
- Mycobacterium tuberculosis
- M. bovis
- M. avium-intracellulare complex
- (MAC)
- M. kansasii
- Obligate aerobes (= upper lobe disease)
What LTR is a granultmatous disease
TB
TB is resistant to what type of killing through what
Resistant intracellular killing resisting phagosome/lysosome fusion:
How is TB spread
Infectious droplets
Where does latent TB reside
Survives in macrophages, resides in granulomas
Diagnosis of TB
Direct observation in sputum/BAL
Culture
MGIT
NAAT
Interferon gamma release assay
TB symptom that isn’t very diagnosist
Caseous necrosis
