Antibiotic Guidelines

Based on NICE (NG250 for pneumonia, NG109/113 for UTI, NG141 for SSTI, NG240 for meningitis, NG199 for C. diff), BASHH for STIs, BSAC for endocarditis, and other UK sources like PHE/UKHSA. Always consult local guidelines, BNF, and specialists. Dates reflect latest updates as of 2025.

1. RESPIRATORY TRACT INFECTIONS 🌬️

1.1 Community-Acquired Pneumonia (CAP) 🫁

• Most Common Pathogens:
  • 🟢 S. pneumoniae (mainstay)
  • 🟣 Mycoplasma pneumoniae, Legionella, C. pneumoniae (atypicals)
  • 🟠 H. influenzae (esp. in COPD)
• Assessment: Use CRB-65 score (NICE NG250). Score 0-1: Outpatient; 2: Hospital; ≥3: Urgent hospital.
• Treatment (NICE NG250):
  • 🚶‍♂️ Low severity (outpatient): Amoxicillin 500mg TDS x 5 days (first-line). If atypical suspected or penicillin allergy: Doxycycline 200mg day 1, then 100mg OD x 4 days OR Clarithromycin 500mg BD x 5 days.
  • 🏥 High severity (hospital, non-ICU): Co-amoxiclav 1g TDS IV/PO + Clarithromycin 500mg BD. Switch to oral when stable.
  • 💉 Severe/ICU: Co-amoxiclav + Clarithromycin + consider adding Levofloxacin if Legionella risk. Add Corticosteroids (e.g., hydrocortisone) for high-severity.
• Duration: 5 days; extend if not improving.

1.2 Hospital-Acquired Pneumonia (HAP) 🎗️

• Pathogens: Gram-negatives (Pseudomonas), MRSA.
• Treatment (NICE NG139): Pip/taz 4.5g TDS IV OR Cefuroxime 1.5g TDS + Metronidazole if anaerobic risk. Add MRSA cover if needed (Vancomycin). Start within 1-4 hours.

1.3 Pharyngitis/Tonsillitis 🤒

• Group A Strep (Centor score ≥3): Phenoxymethylpenicillin (Pen V) 500mg QDS x 10 days (NICE). Allergy: Clarithromycin 250mg BD x 5 days.

2. URINARY TRACT INFECTIONS (UTI) 🚽

2.1 Uncomplicated Lower UTI (Cystitis) 💧

• #1 Pathogen: 🟣 E. coli.
• Treatment (NICE NG109): Non-pregnant women: Nitrofurantoin 100mg BD x 3 days (first-line). Alternatives: Trimethoprim 200mg BD x 3 days (if resistance <20%). Pregnant women: Nitrofurantoin x 7 days (avoid 3rd trimester). Men: x 7 days.
• Delay if mild: Back-up prescription with self-care advice.

2.2 Acute Pyelonephritis 🩸

• Treatment (NICE NG109): Ciprofloxacin 500mg BD x 7 days (avoid if resistance high; MHRA warnings). Alternatives: Co-amoxiclav 500/125mg TDS x 7-10 days OR Cefalexin 500mg QDS x 7-10 days.

2.3 Catheter-Associated UTI 🩹

• Treatment (NICE NG113): Only treat symptomatic. Ciprofloxacin 500mg BD x 7 days OR Co-amoxiclav. Remove/replace catheter.

3. SKIN & SOFT TISSUE INFECTIONS 🩹

• 3.1 Cellulitis/Erysipelas 🟡

  • Pathogens: 🟡 S. aureus, 🔴 S. pyogenes.
  • Treatment (NICE NG141): Flucloxacillin 500mg QDS x 5-7 days (PO). Severe: IV 1-2g QDS. Allergy: Clarithromycin 500mg BD OR Clindamycin 300mg QDS.
  • MRSA risk: Clindamycin or Doxycycline.

• 3.2 Abscess/Boil 🩸

  • I&D primary. Antibiotics if systemic symptoms: Flucloxacillin + Clindamycin for MRSA cover.

3.3 Necrotizing Fasciitis ⚠️

• Treatment: Urgent surgery + Clindamycin 600-900mg IV TDS (toxin suppression) + broad-spectrum (e.g., Pip/taz 4.5g TDS).

4. CENTRAL NERVOUS SYSTEM 🧠

• 4.1 Bacterial Meningitis (Age-Based) 💉

  • Empiric (NICE NG240/UK JSSG): Give IV antibiotics ASAP (within 1 hour if sepsis). Ceftriaxone 2g BD (adults) + Dexamethasone 10mg IV QDS (before/with first dose, if pneumococcal suspected).
  • Neonates: Cefotaxime + Ampicillin (Listeria cover).
  • Children/Young Adults: Ceftriaxone (meningococcus/pneumococcus).
  • Adults >50/Elderly: Add Ampicillin 2g QDS for Listeria.
  • Duration: 7-14 days depending on organism.

4.2 Brain Abscess 🩸

• Treatment: Ceftriaxone 2g BD + Metronidazole 400mg TDS + consider Flucloxacillin. Surgery if needed.

5. GASTROINTESTINAL INFECTIONS 🤢

5.1 Bacterial Diarrhea 🦠

Pathogen	Treatment (NICE/PHE)
🟣 Salmonella (non-typhi)	Supportive (avoid abx unless severe)
🟣 Shigella	Ciprofloxacin 500mg BD x 3 days
🟤 C. difficile	Vancomycin 125mg QDS PO x 10 days (first-line, NICE NG199). Severe/recurrent: Fidaxomicin 200mg BD x 10 days. Stop offending abx.
🟣 Campylobacter	Supportive; Azithromycin if severe

5.2 Intra-abdominal Infections 🫀

• Treatment: Pip/taz 4.5g TDS IV OR Ceftriaxone 2g OD + Metronidazole 400mg TDS.

6. SEXUALLY TRANSMITTED INFECTIONS 🍆

7. BONE & JOINT INFECTIONS 🦴

7.1 Osteomyelitis 🦴

• Empiric: Flucloxacillin 1-2g QDS IV (S. aureus cover). Add Clindamycin if MRSA.
• Duration: 4-6 weeks total (IV 1-2 weeks, then oral switch if stable, per BSAC/BOA).
• Children: Early OPAT consideration (BOAST).

7.2 Septic Arthritis 💧

• Treatment: Urgent aspiration/drainage + Flucloxacillin IV. Gonococcal: Ceftriaxone.
• Duration: 2-4 weeks IV/PO.

8. ENDOCARDITIS ❤️

9. HIGH-YIELD EMERGENCY ANTIBIOTICS 🎯

• Neutropenic Fever: Pip/taz 4.5g TDS IV (or Ceftazidime).
• Meningitis (empiric): Ceftriaxone 2g BD IV + Dexamethasone.
• Sepsis (empiric): Pip/taz + Gentamicin (NICE sepsis bundle).
• Bite wounds: Co-amoxiclav 500/125mg TDS x 5 days (NICE NG184).
• Catheters: Vancomycin + remove device.

10. RESISTANCE PATTERNS ⚠️

• MRSA: Vancomycin, Daptomycin, Linezolid.
• VRE: Linezolid, Daptomycin.
• ESBL: Carbapenems (e.g., Ertapenem).
• Pseudomonas: Dual therapy e.g., Ceftazidime + Ciprofloxacin.

🩺 KEY TAKEAWAYS FOR UK EXAMS (PLAB/MRCP): - NICE emphasis: Antimicrobial stewardship, short courses, local resistance data. - MRSA/Pseudomonas: Risk assess (hospitalisation, ICU). - Sepsis: Within 1 hour antibiotics (NICE NG51). - Prophylaxis: No routine for IE (NICE CG64); focus on hygiene. - Always: Source control + de-escalate based on cultures. Consult BNF for doses.