Microbiology Flashcards
Why has there been a reduction in children getting infections caused by H.infleunzae?
Hib vaccine
What are the conditions needed for growing H.influenzae colonies?
Chocolate agar - blood agar, heated to 80 deg C
Containing factor 5 + 10
Big cause of COPD exacerbations
H. influenzae
How do mycobacteria differ from normal bacteria?
Intracellular
Alongside RIPE, what should also given in TB?
Vit B6 !
Bc isoniazid depletes VitB6 which causes peripheral neuropathy
Causes Osteomyelitis
Haematogenous - Staph Aureus
Exogenous/Local - Staph Epidermidis !
Why is treating Osteomyelitis so difficult?
How do you overcome this problem?
Vascular supply to bone may be poor
Longer Abx therapy! + using Abx that can penetrate bone tissue
How does the treatment for TB osteomyeltitis and pulmonary TB differ?
Osteomyeltitis TB is longer
12 months not 6
Causes Septic Arthritis
depends on who
Prosthetic joint - staph epidermidis!
Young/sexually active - gonococcal
IVDU - psuedomonas aeuriginosa
Immuno comp - TB
Children - Staph aereus, group A strep and gram -ve bacilli
Skin infections common cause
Most are gram +ve
Staph aereus, strep pyogenes
Soft tissue sepsis presentation?
Inflam cardinal signs of local
Systemic - fever, sweats, rigors
What layer does cellulitis affect?
SC tissue
Who does cellulitis tend to affect?
Patients with :
Ulcers - Vascular / DM patients
Tinea pedis
Obesity
SKin conditions - eczema
Cause Cellilitis
Strep Pyogenes
Staph aureus
What MUST you distinguish cellulitis from?
DVT !!!!!!!!!!!!!!!!!!!
Ix Cellulitis
Clinical diagnosis
Blood culture - ↑vol sample, more than 1 size and more than 1 time
Tx Cellulitis
Flucloxacillin
1st Line ABx treatment for staph aureus
Flucloxacillin
Lowenstein-Jensen
Stains for?
Myco TB
Blood agar
for?
Anaerobes
e.g. fusobacteria
Charcoal agar
For?
Campylobacer jejuni
Chocolate agar
For?
Anaerobes
e.g. S. pneumoniae
MacConkey
Stains for?
Lactose Fermenting bacteria
Pathogen causing Pneumonia?
Strep Pneumoniae
Pathogen causing Bronchitis?
Adenovirus - Acute
Rhinovirus - Chronic
Define pathogen
Organism that causes disease
Define commensal
Organism that colonises host but causes no disease normally
Define Opportunist pathogen
Microbe that only causes disease if host defence is compromised
Define Virulence or Pathogenicity
The degree to which an organism is pathogenic
Describe the stages of Gram staining
Come In And Stain
- Fixate to microscope slide with heat or methanol
- Apply Crystal violet - all cells turn purple
- Apply Iodine (Mordant) - crystal violet-iodine complexes form
- Use Alcohol (acetone or ethanol) to decolourise and distinguish between +ve and -ve
- Apply counterstain Safranin to stain Gram -ve pink
Why does Gram +VE stain purple?
Thick layer of peptidoglycans
What is coagulase?
Enzyme produced by S. Aureus that converts soluble fibrinogen to insoluble fibrinogen
Why might you use Beta Lactams or Glycopeptides against gram pos bacteria?
there’s others u can use, not only for gram pos - but why miiight you?
Because Beta Lactams and Glycopeptides inhibit cell wall synthesis
Gram +ve bacteria have thick cell walls!!! make them vulnerable!!!!!!
If penicllin is CI (bc penicllin allergy), what might you use instead?
Macrolides
Why is folate important for the baby during pregnancy?
Prevents spine bifida!!
What Abx for MRSA?
Vancomycin
What are mycobacteria?
Aerobic, non-spore forming, non-mobile bacilli
How to identify virsuses?
PCR + nucleic acid amplification tests (NAAT)
OR serology