Antimicrobials in Maternity Care – Comprehensive Study Notes

OVERVIEW & LEARNING OBJECTIVES

• Focus: Impact of antimicrobials on maternity care and the midwife-prescriber’s responsibilities.
• Core aims:
  • Foster shared decision-making (“partnership”) with pregnant people who may be reluctant to medicate.
  • Practise judicious, guideline-based antibiotic use to curb antimicrobial resistance (AMR).
  • Shorten courses where evidence shows equal efficacy.
  • Always consider: allergy history, likely organisms, scope of midwifery practice.

PATIENT-CENTRED CONVERSATIONS

• Revisit medication attitudes repeatedly during pregnancy; opinions often change as circumstances evolve.
• Discuss home-preparedness issues (antibacterial soaps, cord-care, dummy hygiene) → educate on AMR consequences.
• Explain that most cord stumps do NOT need treatment; mild ooze/colour change is normal separation.

PRINCIPLES OF ANTIMICROBIAL STEWARDSHIP

• Prescribe only when clearly indicated.
• Identify causative organism whenever possible; start empiric therapy only when delay is unsafe (e.g., symptomatic UTI in pregnancy).
• Prefer narrow-spectrum, single-agent therapy → avoids drug-interactions & resistance.
• Use sufficiently high doses and the SHORTEST effective duration (now usually $5$ days; very few agents >5 days).
• Stress strict dose-timing: fixed intervals (e.g., exactly $8$ h); encourage dose-schedule “planning” at start.
• Complete full course even if symptoms resolve early; stopping at $3$/$5$ days increases AMR risk.

ALLERGY & ANAPHYLAXIS ASSESSMENT

• True allergy = immunological (IgE-mediated) reaction; obtain detailed description of previous events.
• Typical early signs (within $1$–$2$ h):
  • Urticaria, pruritus
  • Angio-oedema (periorbital, lip swelling)
  • Bronchospasm → potential progression to anaphylaxis.
• Statistics: Penicillin hypersensitivity $4\text{–}8\%$; anaphylaxis $1–4/10\,000$, of which $\approx 10\%$ fatal.
• Rule: If convincing history, AVOID the culprit drug; cross-reactivity penicillin↔cephalosporin $3\text{–}8\%$.

BETA-LACTAM ANTIBIOTICS

• Mechanism: Inhibit bacterial cell-wall synthesis ⇒ bactericidal.
• Two main families used in maternity:
  • Penicillins (incl. amoxicillin, flucloxacillin, Augmentin)
  • Cephalosporins

Flucloxacillin

• Indications: Mastitis, uncomplicated superficial wound infections (C-section, perineal).
• Dose: $500\,\text{mg}$ PO $q6h$ ($4\times/\text{day}$) for $5$ days.
• Must be taken on EMPTY stomach → $\ge1$ h before or $\ge2$ h after food (pharmacy labels this).
• Rare adverse event: Cholestatic hepatitis (itch, mild jaundice) — more common with age or pre-existing LFT issues.

Amoxicillin

• Rising $\approx48\%$ E.coli resistance → NOT suitable for empiric symptomatic UTI in pregnancy.
• Appropriate only when culture shows susceptibility (e.g., asymptomatic bacteriuria).
• Dose: $500\,\text{mg}$ PO $q8h$ for $5$ days (may escalate if ineffective).
• Ineffective vs. Staph. aureus.

Augmentin (Amoxicillin $+$ Clavulanic Acid)

• Formulation: $500\,\text{mg}$ amox $+125\,\text{mg}$ clavulanate per tab.
• Use: Cystitis when β-lactamase-producing strains suspected and no allergy/liver disease.
• Contraindicated in pre-term labour owing to neonatal necrotising enterocolitis risk.
• Dose: $1$ tab PO $q8h$ for $5$ days.

Cephalosporins (e.g., Cefaclor)

• Last-line oral option for UTI because of resistance concerns; liaise with obstetric team first.
• Example dose (Cefaclor): $250\,\text{mg}$ PO $q8h$; severe infections $500\,\text{mg}$ PO $q8h$, $5$ days.

MACROLIDES

• Erythromycin / Azithromycin → alternatives when penicillin allergy.
• Must involve obstetric/ID team before prescribing.
• Erythromycin for mastitis: $400\,\text{mg}$ PO $q6h$ for $7$ days; high GI side-effects ↓ adherence.
• Azithromycin for Chlamydia: single $1\,\text{g}$ PO dose; partner Tx not within midwife scope (grey area). Test-of-cure required.

AMINOGLYCOSIDES (Gentamicin — MEDICAL PRESCRIPTION ONLY)

• Indications: Pyelonephritis, septicaemia (IV in hospital).
• Potent, broad-spectrum; risk of oto- & nephro-toxicity, especially if >$72$ h. Trough levels monitored when prolonged.

OTHER KEY AGENTS

• Metronidazole (Flagyl):
  • Used by obstetricians for Trichomonas, Bacterial Vaginosis (BV).
  • Interacts with alcohol → severe nausea/headache (disulfiram-like).
  • Higher dose near term requires specialist input.
• Nitrofurantoin:
  • Broad activity vs. E.coli; avoid in G6PD deficiency; enhanced absorption with food.
  • Standard UTI regimen: $50\,\text{mg}$ PO $qid$ for $5$ days.
  • Avoid urine alkalinisers.
• Trimethoprim:
  • Contra-indicated 1st trimester (folate antagonist).
  • Acute UTI (2nd–3rd trimester): $300\,\text{mg}$ PO nocte x $3$ days (ONLY 3-day course in list).

ANTIFUNGALS

• Vaginal Candidiasis very common in pregnancy.
• First-line topical imidazoles (both subsidised):
  • Clotrimazole $1\%$ cream (6-day intravaginal course using applicators; tube contains $35\,g$ → $30\,g$ intravaginal + $\approx5\,g$ external itching areas).
  • Miconazole $2\%$ cream if prior success/failure of clotrimazole.
• Oral Fluconazole NOT recommended in pregnancy (safe postpartum).
• Oral thrush in mother/baby: Nystatin suspension.

PRESCRIBING PRACTICE & COLLABORATION

• Always consult GP/obstetrician in allergy, complex infection, renal/hepatic disease or remote settings.
• Establish strong pharmacist relationships; rely on them for patient counselling (e.g., food timing labels).
• Keep meticulous documentation of discussions, restrictions, allergy checks.

EXAM/REVISION TIPS (as per lecturer)

• Memorise: drug, dose, frequency, duration.
• Trimethoprim = ONLY $3$-day course; all others start at $5$ days; $7$ days reserved for treatment failure.
• Know empty-stomach rule for flucloxacillin.
• Recognise AMR statistics (e.g., $48\%$ E.coli resistant to amoxicillin).
• Remember cross-reactivity $3\text{–}8\%$ penicillin → cephalosporin.

ETHICAL & PRACTICAL IMPLICATIONS

• Overprescribing fuels AMR, jeopardising future mothers/infants.
• Balancing maternal autonomy with fetal safety requires transparent risk–benefit dialogue.
• Ensuring equitable care in rural/remote areas may need tele-consultations.

QUICK-REFERENCE DOSE SUMMARY (bullet version)

• Flucloxacillin mastitis $\rightarrow$ $500\,\text{mg}$ PO $qid$ x $5$ d (empty stomach)
• Amoxicillin asympt. bacteriuria $\rightarrow$ $500\,\text{mg}$ PO $tid$ x $5$ d
• Augmentin cystitis $\rightarrow$ $1$ tab ($500/125\,\text{mg}$) PO $tid$ x $5$ d (avoid pre-term)
• Cefaclor last-line $\rightarrow$ $250$–$500\,\text{mg}$ PO $tid$ x $5$ d (consult team)
• Erythromycin (pen-allergy mastitis) $\rightarrow$ $400\,\text{mg}$ PO $qid$ x $7$ d
• Azithromycin chlamydia $\rightarrow$ $1\,\text{g}$ PO once (test-of-cure)
• Nitrofurantoin UTI $\rightarrow$ $50\,\text{mg}$ PO $qid$ x $5$ d
• Trimethoprim UTI (>1st T) $\rightarrow$ $300\,\text{mg}$ PO nocte x $3$ d
• Clotrimazole vag. thrush $\rightarrow$ 1 applicator nightly x $6$ d (+ external cream)

CLOSING REMINDER

• “Aim for excellence”: consult, document, review, and reinforce patient education to safeguard both mother and baby while combating the global threat of antimicrobial resistance.