Pneumonia Flashcards
What are the three main routes microorganisms gain access to the lower resp. Tract?
Inhalation as aerosolised particles
Enters lung via bloodstream from extrapulmonary site of infection
Aspiration of oropharyngeal contents
What is pneumonia ?
Inflammation of have lung parenchyma caused by an infective agent.
Usually bacterial, but can also be viral, fungal or parasitic.
Occurs when an infection agent gains access to the lower bronchial tree and alveoli host defences are impaired, or the organism is particularly virulent
What happens to aspirated microorganisms if the host immune system functions optimally?
Aspirated microorganisms are cleared from the region before infection can become established
What happens to aspirated microorganisms if the lung defences are impaired?
This can result in pneumonia.
How do viruses suppress the antibacterial activity of the lung in pneumonia?
Impairing alveolar macrophage function and mucociliary clearance. This sets the stage for secondary bacterial pneumonia,
What are some other factors that decrease mucociliary transport?
Also depressed by ethanol, narcotics and obstruction of a bronchus
What are the risk factors for pneumonia?
Age Certain diseases Smoking and alcohol abuse Hospitalisation in ICU Having COPd and using ICS >24 weeks Exposure to certain chemicals or pollutants Surgery or traumatic injury Ethnicity
How is age a risk factor for pneumonia?
> 65 years and children are more susceptible
How are certain diseases a risk factor for pneumonia?
HIV/AIDS,
neuromuscular diseases that affect breathing,
UTI migration of bacteria
How is smoking and alcohol abuse a risk factor for pneumonia?
Alcohol interferes with gag reflex of blood cells
Smoking causes paralysis of cilia
How is hospitalisation in an ICU a risk factor for pneumonia?
HAp is serious compared to other penumoniae and is acquired by patients who need mechanical intervention. Breathing tube bypasses normal defences and prevents coughing.
How is using an ICS >24 weeks a risk factor for pneumonia?
Makes the patient immunosuppressed, making entry of microorganisms easier
How is exposure to certain chemicals and pollutants a risk factor for pneumonia?
Working around agriculture, construction or around certain industrial chemicals or animals, air pollution or toxic fumes can contribute to lung inflammation which makes it harder for the lungs to clear themselves
How is surgery or traumatic injury a risk factor for pneumonia?
Makes coughing difficult
Lying down causes mucous to collect in the lungs
How is ethnicity a risk factor for pneumonia?
There are some possible ethnic driven factors e.g. Maori more prone to getting pneumonia.
What is the pathophysiology of pneumonia ?
Nominally, alveolar macrophages are huge main cells which respond to bacteria reaching lower airways.
If the microbial inoculum is too high or too virulent to be stopped by AM alone, polymorphonuclear neutrophils are recruited to the alveoli from the vascular compartment.
Cytokines secreted by AM (TNFα, IL-1β, IL-6, and IL-8) attracted PMN enhanced for phagocytosis to destroy the invading pathogens.
Excessive cytokine production also has deleterious effects such as sepsis leading to multi organ failure and death. Other cytokines (IL-10) balance this, by attenuating several inflammatory mechanisms
What is sepsis?
Systemic inflammatory response
What are the organisms responsible for community acquired pneumonia?
Streptococcus pneumoniae (gram +, most common)
Mycobacterium pneumoniae,
Legoniella,
C. pneumoniae,
Haemophilus influenzae,
Variety of viruses including influenza
What proportion of pneumonia is community acquired?
Up to 75%
What is community acquired pneumonia?
Infection of the alveoli, distal airways and interstitial of lungs which occurs outside hospital settings
What are the typical and frequent symptoms of CAP?
Typical:
Fever, cough (can be productive or non productive. Purulent sputum often coloured) pleuritic chest pain, chills and/or rigors, dysponea, increased respiration rate >20
Frequent: headache, nausea, vomiting, diarrhoea, fatigue, joint and muscle pain
What are the causative agents of hospital acquired pneumonia?
Staphylococcus aureus (MRSA) during outbreak
E. Coli
Clebsiella pneumoniae
Pseudomonas argeunosa
Which bacteria organisms is found in mechanical ventilation?
Pseudomonas argeunosa
What is the criteria for HAP?
Symptoms occur 48-72 hours post admission to hospital
What are the risks of HAP?
Prior antibiotic use,
H2 receptor antagonists (proton pump inhibitors?)
Severe illness
What does diagnosis of HAP include?
Fever, Leukocytosis/leukopenia Purulent sputum, Worsening respiratory status Appearance of thick, neutrophil-laden respiratory secretions
Established by new infiltrate on chest radiograph
What is health care associated pneumonia ?
CAP caused by staphylococcus Aureus and gram negative rods observed primarily in elderly, especially those residing in rest homes, and in association with alcoholism and other debilitating conditions
What is consolidation?
Solidification into a firm dense mass of a region of lung tissue which is normally compressible.
This occurs through accumulation of inflammatory cellular exudate in the alveoli and adjoining dcuts resulting in alveolar space that contains liquid instead of gas
What makes up the liquid causing consolidation in pneumonia?
Pulmonary edema,
inflammatory exudate,
pus,
inhaled water or blood
What is atypical pneumonia?
Caused by M. Pneumoniae, C pneumoniae, or Legionella
Has a slow onset, unproductive cough and patchy consolidation on X-ray
Usually hospital acquired.
What is typical pneumonia?
Caused by S. Pneumoniae, H influenzae.
Has a quicker onset
How is pneumonia clinically presented?
Signs and symptoms
Physical examination
Chest radiograph
Laboratory examination
How are the signs and symptoms of pneumonia clinically presented?
Abrupt onset of fever, chills, dysponea, and productive cough
Rust coloured sputum or haemoptysis
Pleuritic chest pain
How is pneumonia clinically presented through physical examination?
Tachypnea and tachycardia
Dullness to percussion
Increased tactile fremitus, whispered pectoriloquy and egophony
Chest wall retractions and grunting respirations
Diminished breath sounds over affected area
Inspiration crackles during lung expansion
How is the chest radiograph of pneumonia clinically presented?
As dense lobar or segmental infiltrate
How is the laboratory examination of pneumonia clinically presented?
Leukocytosis WITH a predominance of polymorphonuclear cells.
Low oxygen saturation in arterial blood gas or pulse oximetry
How is treatment of pneumonia approached?
Confirm diagnosis using signs, symptoms, chest X-ray
Assess severity
Assess likely causative organisms (by source of infection)
Initiate antibiotics (select on empiric basis initially)
How is diagnosis of pneumonia confirmed?
Analysing the Chest X-ray Sputum culture Full blood count C-reactive protein Erythrocytes sedimentation rate Urinary antigen test
How can the chest X-ray confirm pneumonia?
Shows either localised consolidation or patchy consolidation
How can a sputum culture confirm pneumonia?
Not that useful as it takes time for results to come back
S. Pneumoniae and H. Influenzae are difficult to grow (resulting in false negative)
S. Aureus and gram- bacteria are easy to grow (resulting in false positive)
How does a full blood count confirm pneumonia?
Presence of increased neutrophils and WBC
How does C-reactive protein confirm pneumonia?
This is an acute phase inflammatory protein synthesised in the liver and is elevated in pneumonia
How does the erythrocyte sedimentation rate confirm pneumonia?
This is an inflammatory marker and is elevated in pneumonia
How does the urinary antigen test confirm pneumonia?
This detects pneumococcal and legionella antigens
What are the two tests used to assess the severity of pneumonia?
PSI - pneumonia severity index
CURB-65
What is the pneumonia severity index?
This helps predicts mortality and involves 5 classes and 20 different levels but was too complicated for health professionals as it required information which was difficult to obtain
What is CURB65?
A simpler test used to assess the severity of pneumonia. Information is easily obtained from primary health professionals, and patients score a point for every criteria they meet:
Confusion Urea >7 mmol/L Respiration rate >30 breaths/min Blood pressure systolic </=60mmHg 65- age
What does a curb score of 0 correlate to?
0.7% chance of mortality within 39 days
Recommended management as an outpatient
What does a curb score of 1 correlate to ?
2.1% of mortality within 30 days
Recommended management as an outpatient
What does a curb score of 2 correlate to?
9.2% mortality within 30 days
Recommended management is admission into hospital
What does a curb score of 3 correlate to?
14.5% chance of mortality within 30 days
Recommended management considers admission into ICU
What does a curb score of 4 correlate to?
40% chance of mortality within 30 days,
Recommended management considers admission into ICU
What are the primary objectives in the management of pneumonia?
Eradication of the offending organisms
Complete clinical cure
What is empirical treatment?
Medical treatment not derived from scientific method, but from observations survey or common use,
In the medical profession, this is also used when treatment is started before a diagnosis is confirmed
Why is empirical treatment used in pneumonia?
Diagnosis of the causative organisms can take time and delay in treatment can harm the patient.
A sputum treatment should be done before the treatment and a follow up sputum should be done.
What does management of pneumonia is consist of?
Positive support therapy
Oxygen therapy to maintain PaO2 > 60mmHg
Specific Antibiotic therapy once pathogen is identified.
Fluid replacement
Isolate patient if multi drug resistant organism is suspected
Observe HR, BO, RR, Temperature, Na+, K+, urea, creatinine, liver enzymes, FBC and CRP every 24-72 hours
Repeat chest X-ray if deterioration or respiratory complication occurs
How is low severity CAP treated?
With amoxicillin for 7 days.
Ampicillin may also be used
How is low severity CAP treated if an atypical pathogen is suspected?
Add clarithromycin (to amoxicillin) and treat for 7 days.
How is low severity CAP treated if staphylococci is suspected?
Add flucloxacillin to amoxicillin.
Treat for 14-21 days
What are alternative treatments for low severity CAP?
Doxycycline or clarithromycin treat for 7 days
What can clarithromycin be substituted with?
Azithrimycin or erythromycin
What can amoxicillin be substituted with?
Ampicillin.
If patient is allergic to penicillin, can use doxycycline, erythromycin,
How is moderate severity CAP treated?
Amoxicillin + clarithromycin
Or
Doxycycline alone
For 7 days
How is moderate severity CAP treated if MRSA is suspected?
Amoxicillin + clarithromycin
Or doxycycline alone for 7 days
And add vancomycin for 14-21 days
How is high severity CAP treated?
Benzyl penicillin + clarithromycin
Or benzyl penicillin + doxycycline
For 7-10 days
How is high severity CAL treated if MRSA is suspected?
Benzyl penicillin + clarithromycin
Or benzyl penicillin + doxycycline for 7-10 days
And add vancomycin for 14-21 days
How is high severity CAP treated if it is a:
Life threatening infection
Gram - organisms suspected
Patient has other comorbidities
Patient lives in long term residential or nursing home?
Co amoxiclav + clarithromycin
OR cefuroxime + clarithromycin
OR cefotaxime + clarithromycin
For 7-10 days.
In what situation would the treatment of life treat ending/G- suspected- comorbidities/ lives long term in residential or nursing home patient with high severity CAP extend to 14-21 days?
If gram - enteric bacilli is suspected
If staphylococci is suspected
How is CAP treated if caused by atypical pathogens?
Clarithromycin for 7-10 days
How is pneumonia treated if caused by high severity legionella (atypical pathogen) ?
Clarithromycin 7-10 days
Add rifampacin for first few days
OR add quinolone and treat for 7-10 days
How is CAP caused by atypical pathogens treated if it is due to chlamydial or mycoplasma infections?
Treat with doxycycline for 14 days
How is early onset HAP treated?
With co amoxiclav or cefuroxime
How is early onset HAP treated if it is life threatening/patient has had antibactieral treatment in the last 3 months/ patient has resistant organisms?
With antipseudomonal penicillin (e.g. Piperacillin + tazobactam)
Or a broad spectrum cephalosporin (e.g. Ceftazidime)
Or an antipseudomonal beta lactam
Or a quinone (e.g. Ciprofloxin)
If MRSA suspected add vancomycin
If severe illness caused by pseudomonas areuginosa, add aminoglycosides
Teat for 7 days, longer if it is pseudomonas areuginosa
How is late onset hap treated?
The same for early onset hap with complications:
Either with antipseudomonal penicillin
Or broad spectrum cephalosporin
Or antipseudomonal beta lactam
Or quinolone
MRSA suspected : add vancomycin
Severe illness caused by p. Areuginosa, add aminoglycosides
Treat for 7 days but longer if it is p. Areuginosa
What are the three criteria patients should meet to be considered to have responded to treatment?
1) fever declines within 72 hours
2) temperature normalises within 5 days
3) respiratory signs return to normal
How long do the abnormalities with penumonia last for?
Fever: 2-4 days Cough: 4-9 days Crackles: 3-6 days Leukocytosis: 3-4 days C-Reactive reroute in: 1-3 days Chest xray abnormalities: 4-12weeks
What are reasons for failing to improve within 48-72 hours?
Wrong diagnosis (patient may have non infectious conditions such as cancer or haemorrhage) Wrong treatment (causative pathogen may be resistant or unusual such as mycobacterial, viral, fungal) Dose may not be sufficient
What factors must be considered when prescribing antibiotics?
Age
Type of penumonia
Allergies to particular treatments
Liver and kidney function
What are macrolides?
E.g. clarithromycin erythromycin
Possess excellent activity against strep pneumoniae and mycoplasma organisms
Bacteriostatic, but can be bacteriocidal at higher doses
Side effects: stomach upset, nausea, vomiting, diarrhoea, heart burn, indigestion
To be given to patients <65 years with no suspected resistance
What is the mechanism of action of macrolides?
They bind irreversibly to the site on the 50S subunit of the bacterial ribosome, inhibiting translocation steps of protein synthesis.
What is clarithromycin ?
A erythromycin derivative (macrolide) with slightly greater activity against H. Influenzae
Contains less GI side effects
What is erythromycin?
A macrolide active against Gram positive bacteria but not gram negative except for H. Influenzae
What is tetracycline?
E.g. Tetracycline hydrochloride, doxycycline
A broad spectrum antibiotic for the treatment against strep. Pneumoniae, H. Influenzae and good for treating chlamydia
Should not be taken with milk, antacids, aluminium, calcium, magnesium, iron and zinc salts due to complexation.
Side effects include stomach/bowel upsets, allergic reactions, and photosensitivity
What is the mechanism of action of tetracyclines?
They bind to the 30S ribosomal subunit in mRNA translation
They inhibit protein synthesis by inhibiting the binding of aminoacyl tRNA to the mRNA-ribosome complex
What are beta lactams?
E.g. Penicillin, augmentin + clauvanic acid
Broad spectrum antibiotic for CAP
Treats against strep pneumoniae, H. Influenzae
Side effects include allergic reactions and GI upset
What is the mechanism of beta lactams?
Covalently binds and inactivates the bacterium’s transpeptidase enzymes, inhibiting the synthesis of the peptidoglycan layer of bacterial cell walls.
Transpeptidase enzymes cross link peptidoglycan in gram positive bacteria like streptococcus and staphylococcus to form a cell wall
What are fluroquinolones?
E.g. Ciprofloxacin, moxifloxacin
Limited use in paediatric patients due to possible destructive lesions of growing cartilage
Side effects include CNS and tendon toxicity
What is the mechanism of action of fluoroquinolones ?
They are bacteriocidal and inhibit DNA gyrase or the topoisomerase II enzyme,p thereby inhibiting DNA replication and transcription
What are aminoglycosides?
E.g. Gentamicin, tobramycin
Effective against gram negative organisms
Side effects include unsteadiness dizzinessm changes in urine output, loss of appetite increased thirst, seizures, vomiting, vestibular and auditory damage, nephrotoxicity
It has a very narrow therapeutic range
What is the mechanism of action of aminoglycosides?
Gram negative organisms allow aminoglycosides to diffuse through the portion channels in their outer membranes
The antibiotic binds to the 30S ribosomal subunit prior to ribosome formation
Polysomes become depleted due to aminoglycosides interrupting the polysome disaggregation and assembly process
Why can aminoglycosides synergise with beta lactam antibiotics?
Beta lactams act on the cell wall synthesis which enhances the diffusion of the aminoglycosides into the bacterium.
