Pathology of Pneumonia: Part 2 - Causitive agents, infection routes and classification Flashcards
what are 2 examples of Gram +ve bacteria that cause pneumonia
Gram +ve bacteria:
- Streptococcus pneumoniae
- Staphylococcus aureus
what are 3 examples of Gram -ve bacteria that cause pneumonia?
- Haemophilus influenzae
- Klebsiella pneumoniae
- Legion pneumophila
what Gram +ve bacteria is the most common cause of community acquired pneumonia
streptococcus penumoniae
which Gram-type of bacteria is the most common cause of hospital acquired pneumonia?
Gram -ve
what are 4 examples of things other than bacteria that can cause pneumonia
- viruses
- mycoplasma (mycobacterium tuberculosis)
- fungi
- inorganic agents (dust/gases)
outline 3 routes that can cause pneumonia
- inhalation of pathogens/inorganic agents
- Dissemination
- Bacteraema phase
what is the main route of infection for pathogens/inorganic agents in pneumonia?
- inhalation of the pathogens/inorganic agents
how can pathogens/inorganic material be transmitted from person to person (Transmission)?
usually carried through water droplets that have either been coughed or sneezed out by an infected individual, and then breathed in by an uninfected individual
what is dissemination (in pneumonia but this is universal)?
- aspiration of oropharyngeal secretions and or gastric contents
can happen when someone vomits
what is bacteraema phase and when can it occur?
When severe bacterial infection somewhere else in the body or vice versa disseminates through systemic circulation to other places.
- can occur shortly after birth (from mother to child)
what 2 environmental factors can increase the chance of infection and disease and how?
Alcohol can reduce the cough reflex, leading to increased aspiration and increased chance of vomtting
cigarette smoke can lead to reduced mucociliary and macrophage action in respiratory tract, so inhalated pathogens can live longer.
classifiation of pneumonia
what are the 3 classifications of pneumonia and give brief description of each type
1. Anatomical classification
- how the infection is spread in the lungs
2. clinical setting in which the disease occurs
- what are the circumstances/factors surrounding the disease
3. microbiological
- identifying the causative agent (the pathogen)
what is the most clinically relevant classification of pneumonia?
- the clinical setting in which disease occurs
what are the 2 sub-classifications of anatomical classification of pneumonia
- lobar pneumonia
- bronchopneumonia
what is lobar pneumonia
- pathogen directly spreads from alveoli-alveoli via alveolar pores, usually throughout whole lung lobe.
what are 3 factors that can cause lobar pneumonia in adults?
- poor hygiene
- malnourishment
- alcoholics
what is bronchopneumonia?
when organisms colonise bronchi and then spread to the alveoli via bronchioles
what happens to affected areas in bronchopneumonia and what is it called when the whole lobe is affected.
- they initially consolidate locally rather than as a whole and eventually the whole lobe is affected.
- called confluent bronchopneumonia when whole lobe is affected.
what 3 types of people are most likely to get bronchopneumonia
- young
- elderly
- immobile people
why is there a blurred distinction between lobar and bronchopneumonia?
due to similarities between confluent bronchopneumonia and lobar pneumonia
clinical setting classification
what are the 6 sub divisions of the clinical setting classification of Pneumonia?
- Community acquired (CAP)
-
Hospital acquired (HAP)
- also known as Nosocomial - Pneumonia of the immuno-compromised
- Aspiration pneumonia
- Necrotising pneumonia and lung abscess
- chronic pneumonia
why are clinical setting sub-classification of pneumonia useful?
useful as each sub-classification is associated with a particular group of pathogens
Community Acquired pneumonia
what is the most common cause of community acquired pneumonia?
streptococcus pneumoniae (Gram +ve)
what anatomical classification of pneumonia is streptococcus pneumoniae (Gram +ve) most associated with?
most associated with lobar pneumonia
what 2 pathogens are linked to COPD + pneumonia comorbidity and neutrophilic asthma
- haemophilus influenzae
- moraxella catarrhalis
what is the most common cause of Gram -ve pneumonia in Community acquired pneumonia and what is it associated with?
- klebsiella pneumoniae
- associated with malnourishment (economically deprived), alcoholics and immobiled individuals
what diseases/disorders is Pseudomonas aeruginosa linked to
- Cystic fibrosis
- neutropenia
what is legionella pneumophila associated with?
associated with legionnaires’ disease
what characterises:
- bacterial pneumonias
- viral pneumonias
Bacterial pneumonias:
- intra-alveolar neutrophilic inflammation
Viral pneumonias:
- interstital lymphocytic inflammation
Hospital acquired pneumonia
what is hospital acquired pneumonia
pulmonary infection leading to pneumonia, acquired during a hospital stay
what are 5 risk factors of hospital acquired pneumonia
- underlying disease
- immunosuppression
- prolonged antibiotic therapy
- invasive access devices
- mechanical ventilators VAP
what bacteria most common cause of hospital acquired pneumonia and what gram-type is it
- staphylococcus aureus
- Gram +ve
what are 2 examples of gram -ve bacteria species that can cause hospital acquired pneumonia
- enterobacteriacae species
- pseduomonas species
immunocompromised pneumonia
what 3 factors are associated with immunocommpromised pneumonia in patients?
- organ transplants
- cancer treatments
- exisiting immunosuppressive diseases
what are the infections that cause immunocompromised pneumonia called and why?
- they are called opportunistic infections
- this is because they wouldn’t normally cause disease in a clinically healthy host
what is a type of bacteria that can cause immunocompromised pneumonia?
Mycobacteria
what is are 3 viruses that can cause immunocompromised pneumonia?
- CMV
- HSV
- VZV
what are 3 fungi that can cause immunocompromised pneumonia
- pneumocystis jiroveci
- Candida
- aspergillus
Aspiration Pneumonia
what 2 things directly contribute to the pneumonia caused in aspiration pneumonia
- irritation of alveoli due to gastric contents
- bacteria in aspirations
what does aspiration pneumonia lead to in terms of lung tissue and what can it cause to lung tissue in survivors of it?
- leads to lung tissue necrotisation
- survivors can have the formation of lung abscess, which can affect overall lung function
What is the respiration method for the most common bacteria found in aspiration pneumonia and where is it found
- anaerobic bacteria
- oral flora
what 4 disorders/body states is aspiration of gastric contents associated with in aspiration pneumonia and give examples of diseases where this happens for 2 of them?
-
Abnormal gag/swallow reflexes
E.G after a stroke or in MS -
Unconsciousness
EG: gastro-oesophageal reflux disease - repeated vomiting
- poor oral hygiene
Necrotising Pneumonia and lung abscesses
what is necrotising pneumonia and lung abscesses?
rare but severe complication/progression of pneumonia due to inflammation and damage causing ischemia, leading to necrosis
what is the most common precursor pneumonia for necrotising pneumonia and lung abscesses
aspiration pneumonia
why do infections usually progress in necrotising pneumonia
because access for antibiotics is restricted
