ANTIBIOTICS
Antibiotics are used to fight bacterial infections.
There are 2 main types:
- Bactericidal: Antibiotic that kills bacteria
- Bacteriostatic: Inhibits growth of bacteria
When bacteria are no longer affected by an antibiotic they are resistant.
Resistance happens because:
- Mutations
- Pathogens have evolved to evade immune systems – struggle is the evolutionary race
Hospital Acquired Infections
They try to combat antibiotic resistance by:
- Only using antibiotics when needed and ensure course of treatment is completed (reduced selection pressure on organisms and destroys all bacteria causing infection)
- Isolating patients with resistant diseases (prevents transmission)
- Good hygiene
- Screening of patients entering a hospital (detection and treatment)
Investigating bacteria and antibiotics:
CORE PRACTICAL
- A sterile nutrient agar plate is seeded with bacteria
- Antibiotic applied to sterile paper discs, lay on agar using sterile forceps
- Seal petri dish but not completely
- Incubate at 30oC for around 24 hours
- Look for inhibition zones around the antibiotic discs (clear zones). Bigger areas indicate a better antibiotic against this species