Microbiology Flashcards
Host defence in nasopharynx
Nasal hairs, ciliated epitheiia, IgA
Host defence in oropharynx
Saliva, coughing, sloughing
Inflammation of nose is called
Rhinitis
Upper respiratory tract gram positive colonisers
Alpha-haemolytic - Streptococcus pneumoniae
Beta-haemolytic - Streptococcus pyogenes
Upper respiratory tract infection causing organism that grows easily on blood agar
Haemophilus influenzae
Another example of upper respiratory tract infection causing organism
Moraxella catarrhalis
Defence in conducting airways
Mucociliary escalator, cough. Mucus has AMP - Anti microbial particles
Why does intubation lead to infections
Intubation inhibits the final stage of the ciliary escalator which helps in expulsion of foreign material from being swallowed or coughed up.
Chest examination and x-ray of acute bronchitis
Normal
When are COPD exacerbations often seen
Following viral infection, fall in temperature, increase in humidity
Symptoms of whooping cough
Pertussis - Paroxysmal coughing with cold like symptoms for 2 weeks. Repeated violent exhalations with severe inspiratory whoop
What causes pertusis
Whooping cough, by Bordetella pertussis
Gram negative bacillus exclusively in humans
Vaccine preventable
How long can whooping cough last
10 days
Contagious period for whooping cough
2 weeks
Diagnosing Bordetella pertusis
Bacterial culture or PCR of pernasal swab (< 21 days)
Serology (Takes long)
Why should a pernasal swab only be taken within 21 days
Post infective cough after 21 days, only positive within 21 days
Treatment of Bordetella pertusis
Antibiotics is < 21 days
Does the alveolar lining have ciliary escalator
No, normally sterile
Diagnosis community acquired pneumonia
Sputum culture, purulence, viral PCR
Pneumococcal pneumonia treatment
5 day course of Amoxicillin and complete recovery
Types of Streptococcus pneumoniae infections
Noninvasive -
Sinus infection, ear infection, pneumonia without spread to bloodstream, URTI
Invasive -
Meningitis, bactaraemia
How can pneumonia be assessed
Consolidation on chest x-ray + CURB65
What is CURB65
Assess pneumonia severity C - Confusion U - Urea > 7 mmol/l R - Respiratory rate > 30/min B - BP < 90 systolic or 61 diastolic 65 - Age > 65
What is legionella pneumoniae
CAP caused by Legionella pneumophila
Diagnosed by serology for legionella antigen
PCR can also be done
Treatment of legionella pneumoniae
Macrolides such as clarythromycin and erythromycin
Quinolones such as levofloxacin
Older macrolide and it’s new derivatives
Older macrolide is erythromycin. Its newer derivatives are clarithromycin and azithromycin
4 C associated with Clostridium difficile infection
Clindamycin, Cephalosporin, Co-Amoxiclav, Ciprofloxacin
Clinical features of legionella pneumonia
Flu like illness which may progress to severe pneumonia with mental confusion, acute renal failure and GI symptoms
How is legionella pneumophila spread
Through contaminated water droplets, warm and damp places such as hot tubs, air-conditioning systems, plumbing systems
Preventing legionella pneumophila in the community
Water supply should be cooled below 20C or heated above 60C
When can amoxicilin not be used
When organism doesn’t have cell wall
What causes walking pneumoniae
Mycoplasma pneumoniae Often in young adults, patient is able to walk about and generally doesn't feel unwell Non-productive coug Malaise Myalgia Rash is often seen
IV drug users are likely to get what type of pneumoniae
Staphylococcus aureus, hematogenous spread leading to cardiovascular infections
