Microbiology 2 Flashcards
What are the host defences associated with the nasopharynx?
Nasal hairs
Ciliate epithelia
IgA
What are the host defences associated with the oropharynx?
Saliva
Sloughing
Cough
What is the common organism associated with epiglottitis?
Haemophilus influenzae type B (HiB)
What are some of the risk factors for getting epiglottitis?
being immunocompromised /immunosuppressed
Transmission of capsulated strain to unvaccinated host
How can you test which organism is causing the epiglottis?
Blood culture
Not throat swab due to irritating the throat and causing resp failure
What antibiotic do you treat epiglottitis with?
Ceftriaxone
What is Haemophilus influenza in terms of stain etc?
Gram negative coccobacillus
What are the host defences in the conducting airways? (trachea and bronchi)
Mucociliary escalator
Cough
AMP’s
Cellular and humoral immunity
How may you get infection in your conducting airways?
By trauma or incubation
Abnormalities with the ciliary elevator for example etc
What type of infections are more common in people with COPD?
Bacterial 50%
Viral 30%
Why are people with COPD more prone to infections?
Over time the inflammation leads to impaired cilliary clearance, effectively reduces the host’s normal defence and leads to increased susceptibility to infection. Which in turn leads to acute exacerbations of COPD. Causes of these exacerbations can be viral or bacterial, and the normal culprets are organisms we routinely associate with standard chest infections
What is one of the most commonly encountered organisms for COPD patients?
Moraxella catarrhalis. Which is a gram negative coccus
How would you test and treat infections in COPD?
Testing
- sputum culture
- sputum purulence
- CXR
Treatment
- only treat if increase in sputum purulence of new CXR change or pneumonia
What is the specific treatment for acute exacerbation of COPD?
- 1st line Amoxicillin 500 mg TDS (5 days)
- 2nd line Doxycycline 200mg D1 > 100 mg D2-5
Aim to cover in 1st instance H. influenzae, M. catarrhalis & S. pneumoniae
What is Cystic Fibrosis?
Inherited disease leads to abnormally viscous mucous – blockages of many tubular structures including conducting airways & lungs.
What are the 2 organisms that you should worry about the most in terms of CF?
Pseudomonas aeruginosa and Burkholderia cepacia
Is acute bronchitis viral or bacterial?
Viral
Is pneumonia viral or bacterial?
Bacterial
Would you usually give antibiotics for acute bronchitis?
Not usually
What is whooping cough and describe some clinical features?
Acute tracheobronchitis “cold like” symptoms for two weeks paroxysmal coughing (2 weeks) repeated violent exhalations with severe inspiratory “whoop”, vomiting common residual cough for month or more
What is the causative organism for whooping cough?
Bordetella pertussis =
Gram negative coccobacillus
How would you diagnose whooping cough:?
Bacterial culture - takes a while?
PCR - more commonly used
- however have to get the swab when the person has only been symptomatic for less than 3 weeks as after 3 weeks the test will show negative for Pertussis
How would you treat whooping cough?
Treat it with antibiotics if <21 days cough
What are the common lung infections and their organisms?
CAP
- S.pneumoina, H.Infleunza
- atypical pneumonia - mycoplasmic pneumonia etc
HAP
TB
What is the rough pathology of CAP?
Organism reaches lungs > immune activation & infiltration (systemic response) > fluid & cellular build up in alveoli leads impaired gas exchange
What are the most common causes of CAP?
Strep pneumonia
(viruses)
H.influenza
etc
How would you diagnose CAP?
Sputum culture
Viral PCR
What is legionella pneumonia?
- It is an atypical pneumonia
- Gram negative bacteria
- It invades alveolar macrophages and then replicates
- Get a flu like illness
- transmitted by inhalation of
water droplets - air conditioning, dodgy hotels etc
How do you diagnose legionella?
Urinary antigen
Culture
PCR
How do you treat legionella?
Levofloxacin
How do you treat CAP mild/mod (0-2)?
antibiotic man
Amoxicillin (doxycycline)
How do you treat CAP severe (3-5) if in ICU/HDU?
antibiotic man
Co-amoxiclav + clarithromycin (levofloxacin)
How do yo treat HAP severe? (antibiotic man)
IV amoxicillin + metronidazole + gentamicin (IV Co-trimoxazole + Metronidazole +/- Gentamicin)
How do you treat HAP non severe? (antibiotic man)
PO Amoxicillin + Metronidazole (PO Co-trimoxazole + Metronidazole)
What is pneumocystis pneumonia?
(PCP)
One of the most frequent and severe opportunistic infections in people with weakened immune systems
- AIDS/HIV
- Immunosuppression
It is due to inhalation of fungus?
How do you treat pneumocystis pneumonia?
co - trimoxaole ? check
What is aspergillus?
A fungal chest infection
usually IC/IS patients
Treatment
Amphotericin B
Voriconazole
Surgery
What is the organism in TB?
Mycobacterium TB
- acid alcohol fast bacilli - thick waxy coat
