Pharmacology
Pharmacology
Core44: Narrow and broad spectrum antibiotics
狭域・広域抗菌薬
🎯 High-yield / 要点：Narrow-spectrum antibiotics target fewer bacteria and preserve microbiome; broad-spectrum antibiotics cover many pathogens but increase resistance and microbiome disruption risk.
Narrow vs broad spectrum / 狭域 vs 広域
| Type | Meaning | When used | Main risk/benefit |
|---|---|---|---|
| Narrow-spectrum | Targets a specific type/family of bacteria | Known pathogen; de-escalation; microbiome-sparing therapy | Less disruption of normal flora |
| Broad-spectrum | Acts against many bacterial groups | Unknown pathogen, severe infection, polymicrobial infection | Higher resistance and microbiome disruption risk |
Narrow-spectrum examples / 狭域抗菌薬の例
- Penicillin G
- Monobactams
- Glycopeptides
- Fidaxomicin
- Metronidazole
- Most antituberculous drugs
Broad-spectrum examples / 広域抗菌薬の例
- Fluoroquinolones
- Aminopenicillins
- Piperacillin
- Cephalosporins
- Carbapenems
- Chloramphenicol
- Doxycycline
Clinical strategy / 臨床戦略
- Start broad when the pathogen is unknown and infection is severe.
- Narrow therapy once culture/susceptibility results are available.
- Prefer narrow-spectrum antibiotics when pathogen is known and coverage is adequate.
Remember / 覚え方
- Narrow = targeted + microbiome sparing
- Broad = useful empirically but resistance risk
- De-escalation is good antimicrobial stewardship