Microbiology (Respiratory) Flashcards
What should the infection control precautions for influenza include?
Aerosol protection for aerosol generated procedures only e.g. intubation/extubation, CPR, bronchoscopy, surgery and post mortem procedures, dental procedures, ventilation, induction of sputum.
When is primary influenzal pneumonia seen most and who can it effect?
Pandemic years, young adults (high mortality).
When is secondary bacterial pneumonia seen and who does it affect most?
Epidemic and pandemic years, more common in infants, elderly/debilitated, pre-existing disease and pregnant women.
What may influenza in pregnancy be associated with?
Perinatal mortality, prematurity, smaller neonatal size and lower birth weight.
What are potential complications of influenza?
Primary influenzal pneumonia, secondary bacterial pneumonia, bronchitis and otitis media.
What is the symptomatic therapy for influenza?
Bed rest, fluids, paracetamol.
What are the antivirals for influenza?
Oseltamivir, zanamivir.
What influenza strain is involved in pandemics?
A
How would you test for influenza?
PCR from nasopharyngeal swabs or throat swabs.
What might other labs use to test for influenza?
Immunofluorescence, antigen detection, virus culture.
How is the killed vaccine for flu produced?
Virus grown in hen eggs or cell culture then inactivated and combined with adjuvant, currently contains 2 different infleunza A and 1 B virus.
Who is the live attenuated vaccine offered to and how is it administered?
All primary school children, administered intranasally.
What are mycoplasma pneumonia, coxiella burnetii and chlamydia (all bacteria) all microbiological causes of?
Community acquired pneumonia.
How is pneumonia caused by mycoplasma pneumonia, coxiella burnetii and chlamydia treated?
All respond to tetracycline and macrolide e.g. clarithromycin.
What is pneumonia caused by mycoplasma pneumonia, coxiella burnetii and chlamydia sometimes known as?
Atypical pneumonia.
How would you confirm what of mycoplasma pneumonia, coxiella burnetii and chlamydia was causing a pneumonia?
By serology: send acute and convalescent bloods to lab in gold top vacutainer. By virus detection: PCR, currently used only for mycoplasma in Tayside.
What type of pneumonia is a common cause, children and young adults have highest incidences and there is a person to person spread?
Mycoplasma pneumoniae.
What 2 diseases does coxiella burnetii cause?
Pneumonia or pyrexia of unknown origin (Q fever).
What animals can people contract coxiella burnetii from?
Sheep and goats.
What is a complication of coxiella burnetii?
Culture negative endocarditis.
What does chlamydia/chlamydophila psittaci cause (usually presents as a pneumonia) and what is it caught from?
Pet birds.
What are the symptoms of bronchiolitis and what happens in severe cases?
1st or 2nd year of life, fever, coryza (common cold), cough, wheeze. Severe cases: grunting, decrease in PaO2, intercostal/sternal indrawing.
When can respiratory and cardiac failure occur in bronchiolitis?
Prematurity, pre-existing respiratory and cardiac disease.
What is the aetiology of bronchiolitis?
Up to 80% of cases due to RSV.
How can the lab confirm the aetiology of bronchiolitis?
By PCR on throat or pernasal swabs.
What infection control measures are used in hospitals for bronchiolitis?
Cohort nursing, handwashing, gowns, gloves.
What virus is the second most common cause of bronchiolitis in children?
Metapneumovirus.
What types of pneumonia does chlamydia trachomatis cause and how can it be diagnosed?
Infantile pneumonia (it is an STI), diagnosed by PCR on urine of mother or pernasal/throat swabs of child.
Describe what a respiratory infection with chlamydophila pneumoniae is like.
Person to person, mostly mild TRI, may be picked up by test for psittacosis.
Where is the middle east respiratory syndrome coronavirus (MERS CoV) most prevalent and what animal reservoir does it use?
Saudi Arabia, dromedary camels.
What are the URT defences?
Nasopharynx: nasal hairs, ciliated epithelia, IgA. Oropharynx: saliva, sloughing (separation of dead from living tissue), cough.
What are the gram positive and gram negative URT colonisers?
Gram positive: alpha-haemolytic streptococci e.g. strep pneumoniae. Beta-haemolytic: streptocooci e.g. strep pyogenes. Staph aureus.
Gram negatives: haemophilus influenzae, moraxella catarrhalis.
What are the conducting airway defences?
Mucociliary escalator, cough, AMPs, cellular and humoral immunity.
What are the symptoms of whooping cough (pertussis)?
Acute trachea-bronchitis, cold like symptoms for 2 weeks, paroxysmal coughing (2 weeks), repeated violent exhalations with severe inspiratory whoop, vomiting common, residual cough for month or more.
What microbe causes whooping cough?
Bordetella pertussis (gm-ve coccobacillus, exclusively human pathogen, vaccine preventable).
How would you diagnose pertussis?
Culture, PCR, serology (paired sera, used to check if antibodies increase over time)
What treatment is there for pertussis?
Antibiotics if less than 21 days cough.
What are the 3 main routes of transmission for respiratory infections?
Contact, airborne, droplet.
What size of particles are more likely to be airborne or droplet?
Airborne: <5 microns. Droplet: >5 microns.
Give examples of diseases that are airborne.
MDR TB, some viruses, RTI undergoing aerosol generating procedures.
What infection control measures are required for airborne diseases?
Require standard infection control precautions and a filtering face piece.
What infection control measures are required for droplets?
Ideally in a single room.
What are the lung defences against infection?
Normally relatively sterile, no ciliary escalator, alveolar lining fluid (surfactant, Ig, complement, FFA, AMP), alveolar macrophages and neutrophils.
How would you test if a pneumonia is caused by strep pneumoniae?
Gram stain sputum (pus cells and gram positive), culture on blood agar produced alpha haemolysis.
What is invasive pneumococcal disease?
Pneumonia with spread to the bloodstream, can cause meningitis.
What is non-invasive pneumococcal disease?
Pneumonia without spread to bloodstream, can cause URT infection, sinus infection, ear infection.
What are the different types of pneumonia?
Acute or chronic, typical (strep pneumo), atypical (complain of non-pulmonary symptoms), hospital acquired pneumonia (including ventilator associated pneumonia), aspiration pneumonia, pneumonia in the immunosuppressed/special populations.
How would you diagnose legionella pneumonia?
Legionella urinary antigen (detects serogroup 1 only), culture, paired serology, now PCR available direct from sputum.
What treatment would you give for legionella pneumonia?
Clarythromycin, erythromycin, quinolones e.g. levofloxacin (only use quinolones in as few cases as possible as high risk c. diff).
Describe legionella.
Common environmental gm-ve bacteria (unusual cell wall structure), obligate intracellular organism (resides within water amoeba which provides nutrients and protection, invades alveolar macrophages).
What are the clinical symptoms and signs of legionella?
Flu like illness which may progress to severe pneumonia, with mental confusion, acute renal failure and GI symptoms.
How does legionella spread?
No person-to-person spread, transmitted by inhalation of contaminated water droplets.
Why does amoxicillin not work on walking pneumonia and what rashes are caused by walking pneumonia?
Organism has no cell wall, bullseyes.
When is staph pneumonia more likely?
Post infleunza (though strep still more common), haematogeneous spread of staph aureus from people who inject IV drugs.
Why is staph aureus pneumonia particularly bad?
PVL toxin is produced by staph aureus
What types of pneumonia does bradycardia occur in and how many beats are lowered per degree rise in temperature?
Legionella, mycoplasma, tularaemia, chlamydia.
