Ampicillin

DRUG NAME: Ampicillin

• Ampicillin trihydrate — used in oral formulations (capsules, dry syrups)
• Ampicillin sodium — used in parenteral formulations (IV, IM injections)

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Therapeutic Class:

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Subclass:

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Schedule (India):

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Route(s):

• Oral (capsules, powder for oral suspension)
• IV bolus (slow IV injection over 3–5 minutes)
• IV infusion (intermittent infusion over 15–30 minutes)
• IM (deep intramuscular injection)

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Biosimilar Status:

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Formulations Available in India:

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PHARMACOKINETICS

• Shorter dosing intervals (q6h or q4h) are more effective than fewer large doses
• Continuous or prolonged IV infusion may be beneficial in critically ill patients (evidence emerging but not yet standard practice in India)

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ADULT INDICATIONS + DOSING — FOR CLINICIAN USE ONLY

1. Resistance landscape in India: Ampicillin resistance rates among common Gram-negative pathogens (E. coli, Klebsiella spp., non-typhoidal Salmonella) in India are very high (>70–90% in many institutional antibiograms). Empirical use of ampicillin alone for suspected Gram-negative infections (UTIs, intra-abdominal, enteric fever) is generally not recommended without prior susceptibility data or strong clinical/epidemiological grounds.
2. Ampicillin retains reliable activity against:Listeria monocytogenes (no known resistance), Enterococcus faecalis (most strains — check local antibiogram for VRE rates), Group B Streptococcus (GBS) (nearly universal susceptibility), Streptococcus pneumoniae (most non-meningeal isolates in India), Streptococcus pyogenes (universal susceptibility), Proteus mirabilis (variable — check susceptibility).
3. Oral route limitation: Oral ampicillin has lower bioavailability (~40–50%) than oral amoxicillin (~70–90%). For most indications where an oral aminopenicillin is appropriate, amoxicillin is preferred over oral ampicillin. Oral ampicillin remains relevant as step-down therapy and where amoxicillin is unavailable.
4. Time-dependent killing: All doses should be administered at regular, evenly spaced intervals (q6h or q4h). Missed or irregularly timed doses significantly reduce efficacy. Counsel patients/staff accordingly.

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Primary Indications (Approved / Standard in India)

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1. When to prefer this drug over alternatives: Ampicillin is the first-line and only reliably effective drug for Listeria meningitis. No beta-lactam alternative has superior efficacy. Listeria is intrinsically resistant to cephalosporins — ⛔ Never use cephalosporins alone if Listeria is suspected.
2. When NOT to use: Known penicillin/ampicillin allergy (anaphylaxis-type). In severe penicillin allergy, co-trimoxazole (TMP-SMX) IV is the alternative. Meropenem may also be considered.
3. NLEM India: Ampicillin injection is included in NLEM India (2022 edition).
4. Time to expected clinical response: Clinical improvement (defervescence, improved sensorium) expected within 48–72 hours. CSF sterilisation typically occurs within 48–96 hours.
5. Criteria for treatment failure: Persistent fever >72 hours, worsening sensorium, repeat CSF showing no improvement in cell count/protein/culture. Consider: inadequate dosing, drug resistance (extremely rare for Listeria), alternative diagnosis, or secondary complication (abscess, hydrocephalus, ventriculitis).
6. Mandatory baseline investigations: Blood cultures (×2 sets), CSF analysis (cell count, protein, glucose, Gram stain, culture, India ink/crypto antigen if immunocompromised), serum creatinine/eGFR, complete blood count.
7. Specialist initiation: ⚠️ Requires specialist supervision (Infectious Disease / Internal Medicine / Neurology). ICU admission recommended for all cases of bacterial meningitis.
8. Indian guideline source: API Textbook of Medicine — Chapter on Bacterial Meningitis; AIIMS Infectious Disease protocol; ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes (2019).
9. Key disease-specific safety warning: ⚠️ Do NOT reduce dose or frequency even if patient appears to improve rapidly. Subtherapeutic CSF levels lead to relapse. Ensure q4h dosing is strictly maintained round the clock.
10. Common dose adjustment scenarios: Renal impairment — extend interval (see Renal Adjustment section). No hepatic dose adjustment needed.

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• Age >50 years
• Neonates and infants <3 months (see Paediatric section)
• Pregnant women
• Immunocompromised (HIV, organ transplant, chronic steroids, malignancy)
• Alcoholism, chronic liver disease
• Diabetes mellitus (relative indication)

• Immunocompetent adults aged 18–50 years with no risk factors — standard empirical therapy is ceftriaxone + dexamethasone ± vancomycin (for suspected resistant Pneumococcus).

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1. When to prefer: Ampicillin is first-line for ampicillin-susceptible E. faecalis IE (which is the majority of E. faecalis in India). Regimen B (ampicillin + ceftriaxone) is preferred when renal function is compromised or there are concerns about aminoglycoside toxicity.
2. When NOT to use: ⛔ Do not use for E. faecium endocarditis (usually ampicillin-resistant — requires vancomycin or daptomycin-based regimen). Do not use for HACEK or staphylococcal IE.
3. NLEM India: Ampicillin injection — included in NLEM India (2022).
4. Time to expected clinical response: Blood culture clearance expected within 3–5 days. Defervescence within 5–7 days.
5. Criteria for treatment failure: Persistent positive blood cultures >7 days despite appropriate therapy, persistent fever >10 days, new embolic events, worsening heart failure, echocardiographic evidence of worsening vegetation or abscess. Consider surgical evaluation.
6. Mandatory baseline investigations: ⚠️ At least 3 sets of blood cultures (from different venepuncture sites, ideally before starting antibiotics). Echocardiography (TTE initially; TEE if prosthetic valve or poor TTE windows). Serum creatinine, eGFR, complete blood count, inflammatory markers (ESR, CRP). Hearing assessment if aminoglycoside planned.
7. Specialist initiation: ⚠️ Mandatory specialist management — Infectious Disease, Cardiology, and/or Cardiothoracic Surgery team involvement. Managed as an inpatient or via OPAT (Outpatient Parenteral Antibiotic Therapy) in select centres.
8. Indian guideline source: API Textbook of Medicine — Infective Endocarditis chapter; AIIMS Cardiology and Infectious Disease protocols; also aligns with AHA/ESC guidelines adapted for Indian organisms and susceptibility patterns.
9. Key disease-specific safety warning: ⚠️ Monitor renal function weekly if using gentamicin combination. Immediate gentamicin TDM and discontinuation if trough exceeds target. Switch to Regimen B if renal function deteriorates. ⚠️ Do not use oral step-down for enterococcal IE — IV therapy for the full duration is standard.
10. Common dose adjustment scenarios: Renal impairment — use Regimen B (ampicillin + ceftriaxone). Extend ampicillin dosing interval if eGFR significantly reduced (see Renal Adjustment).

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• Prosthetic heart valves (mechanical or bioprosthetic)
• Previous infective endocarditis
• Congenital heart disease (unrepaired cyanotic, repaired with prosthetic material within 6 months, repaired with residual defects adjacent to prosthetic material)
• Cardiac transplant recipients with valvulopathy
• Rheumatic heart disease with significant valvular lesions (relevant in India — high RHD burden)

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• Positive GBS rectovaginal culture at 35–37 weeks gestation
• GBS bacteriuria during current pregnancy
• Previous infant with invasive GBS disease
• Unknown GBS status PLUS any of: preterm labour <37 weeks, prolonged rupture of membranes ≥18 hours, intrapartum fever ≥38°C

1. When to prefer ampicillin: When penicillin G is unavailable (which is common in many Indian hospitals — penicillin G injection shortage is frequent). Ampicillin is the standard alternative.
2. When NOT to use: Penicillin allergy with anaphylaxis history → use clindamycin 900 mg IV q8h (if GBS susceptible) or vancomycin 20 mg/kg IV q8h (max 2 g per dose) if susceptibility unknown.
3. NLEM India: Ampicillin injection — included in NLEM India (2022).
4. Expected response: Prophylaxis — no ”response“ expected. Adequacy defined by at least one dose ≥4 hours before delivery. Neonatal GBS risk reduction: >80% with adequate prophylaxis.
5. Key safety warning: ⚠️ This is a prophylactic indication. Do NOT wait for culture results if risk factors present and delivery is imminent. Start prophylaxis immediately when indicated.
6. Indian guideline source: FOGSI (Federation of Obstetric and Gynaecological Societies of India) guidelines; API Textbook — Obstetric Infections; ICMR AMR guidelines (supportive).

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1. When to prefer ampicillin: In Indian district hospitals or settings where IV amoxicillin-clavulanate or ceftriaxone may not be available. Ampicillin IV is a reasonable empirical option for non-severe hospitalised CAP, especially if local antibiogram shows reasonable S. pneumoniae susceptibility. Also appropriate as definitive therapy when S. pneumoniae is confirmed susceptible.
2. When NOT to use: ⚠️ Do NOT use as monotherapy — must be combined with macrolide or fluoroquinolone for atypical coverage. Do NOT use if beta-lactamase-producing H. influenzae is likely (use amoxicillin-clavulanate or cephalosporin). Do NOT use for severe CAP requiring ICU (use ceftriaxone/cefotaxime + macrolide/fluoroquinolone per API/ICMR guidelines). Do NOT use for hospital-acquired or ventilator-associated pneumonia.
3. NLEM India: Ampicillin injection — included in NLEM India (2022). Amoxicillin is the preferred oral aminopenicillin in NLEM.
4. Time to expected clinical response: Defervescence and clinical improvement within 48–72 hours.
5. Treatment failure criteria: Persistent or worsening fever at 72 hours, worsening hypoxia, radiographic progression, new organ dysfunction. Broaden coverage, obtain sputum/blood cultures, consider resistant organisms, alternative diagnoses (TB, fungal, viral), or complications (empyema, abscess).
6. Mandatory baseline investigations: Chest X-ray, SpO₂/ABG, blood cultures (×2 before antibiotics), complete blood count, serum creatinine, CRP or PCT (if available). Sputum Gram stain and culture (if obtainable).
7. Specialist initiation: Not required for general hospitalised CAP — can be initiated by any treating physician.
8. Indian guideline source: ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes (2019); API Textbook — Community-Acquired Pneumonia chapter.
9. Key safety warning: ℹ️ In areas with high beta-lactamase-producing H. influenzae prevalence, consider amoxicillin-clavulanate or ceftriaxone as first-line rather than ampicillin alone.
10. Common dose adjustment scenarios: Renal impairment — adjust interval. Elderly — dose based on eGFR.

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1. When to prefer: ONLY after susceptibility confirmation. Particularly relevant for E. faecalis UTI (intrinsically ampicillin-susceptible, often resistant to cephalosporins) — ampicillin is the drug of choice for Enterococcal UTI. Also useful for susceptible Proteus mirabilis UTI.
2. When NOT to use: ⛔ Do NOT use empirically for UTI in India. Do NOT use for catheter-associated UTI without susceptibility data. Do NOT use for recurrent UTI prophylaxis.
3. NLEM India: Ampicillin — yes, included. However, ICMR AMR guidelines do NOT recommend empirical ampicillin for UTI in India.
4. Time to expected clinical response: Symptom improvement within 48–72 hours. If no improvement, reassess susceptibility and consider alternative.
5. Treatment failure criteria: Persistent symptoms at 72 hours, positive repeat culture, relapse within 2 weeks.
6. Mandatory baseline investigations: Urine culture and sensitivity (MANDATORY before starting ampicillin for UTI). Serum creatinine, complete blood count. Imaging (USG KUB) for complicated UTI or pyelonephritis.
7. Specialist initiation: Not required — can be prescribed by any physician once susceptibility is confirmed.
8. Indian guideline source: ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes (2019) — specifically recommends culture-directed therapy when aminopenicillins are considered for UTI.
9. Key safety warning: ℹ️ Do not assume susceptibility even if the organism is E. coli — always check the individual isolate’s susceptibility.
10. Dose adjustment: Renal impairment — extend dosing interval (see Renal Adjustment).

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1. When to prefer: Only for fully susceptible S. typhi or S. paratyphi (ampicillin MIC ≤ 2 mcg/mL). May be cost-effective in susceptible cases compared to ceftriaxone or azithromycin.
2. When NOT to use: ⛔ Do NOT use empirically. MDR and fluoroquinolone-resistant typhoid is common in India — wait for susceptibility. Do NOT use for chronic carriers (oral amoxicillin or ciprofloxacin are preferred for carrier eradication).
3. NLEM India: Yes — ampicillin is included.
4. Time to expected clinical response: Defervescence expected within 3–5 days of appropriate therapy (may take up to 7 days). Slow clinical response is expected with Salmonella.
5. Indian guideline source: ICMR AMR guidelines (2019); API Textbook — Enteric Fever chapter.

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• Enterococcus faecalis — ampicillin is first-line
• Listeria monocytogenes — ampicillin is first-line (often + gentamicin)

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• Metronidazole (for anaerobic coverage) AND
• Gentamicin or a third-generation cephalosporin (for Gram-negative coverage)

1. When to prefer ampicillin in this context: When Enterococcal coverage is specifically needed (post-operative peritonitis, biliary infections, hepatobiliary surgery, liver transplant). In community-acquired, non-complicated appendicitis or cholecystitis managed surgically, Enterococcal coverage is generally NOT needed.
2. When NOT to use: ⛔ Not as monotherapy. Not for hospital-acquired intra-abdominal infections with suspected resistant Gram-negatives — use piperacillin-tazobactam or carbapenem-based regimens.
3. Indian guideline source: API Textbook — Peritonitis chapter; AIIMS Surgical Infectious Disease protocols.
4. Key safety warning: ⚠️ Monitor renal function closely when combining ampicillin with gentamicin, especially in post-operative patients who may have fluctuating renal function.

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• GAS Pharyngitis: Penicillin V or amoxicillin are first-line. Ampicillin is a second-line oral option. Confirm GAS by rapid antigen test or throat culture before prescribing antibiotics. Treating GAS pharyngitis prevents acute rheumatic fever — very relevant in India.
• Acute Otitis Media (AOM): Amoxicillin is first-line. Ampicillin is an alternative if amoxicillin is unavailable. Most paediatric AOM is managed with amoxicillin (see Paediatric section).
• Acute Bacterial Sinusitis: Amoxicillin or amoxicillin-clavulanate preferred. Ampicillin oral is a second-line option.

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Secondary Indications — Adults Only (Off-label, if any)

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• Evidence quality: Moderate (observational data, expert consensus in Indian hepatology practice)
• Indian source: API Textbook — Hepatology section; AIIMS Hepatology protocol
• Clearly marked: OFF-LABEL but accepted standard practice in India

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• Evidence quality: Strong (established obstetric practice, multiple observational studies)
• Indian source: FOGSI guidelines; API Textbook — Obstetric Infections
• Clearly marked: OFF-LABEL but accepted standard practice in India

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• Evidence quality: Strong (established standard of care in obstetric practice)
• Indian source: FOGSI guidelines; AIIMS Obstetrics protocols
• Clearly marked: OFF-LABEL but accepted standard practice in India

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• Evidence quality: Strong (Mercer RCT, ORACLE trial; endorsed by multiple obstetric guidelines)
• Indian source: FOGSI PPROM guidelines; API Textbook — Obstetric Complications
• ⛔ Do NOT use amoxicillin-clavulanate for PPROM latency antibiotics — associated with increased risk of neonatal necrotising enterocolitis (ORACLE II trial).
• Clearly marked: OFF-LABEL but accepted standard practice in India

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• Evidence quality: Weak (case series, expert consensus — disease extremely rare)
• Clearly marked: OFF-LABEL
• Specialist only

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PAEDIATRIC DOSING (Specialist Only)

• ⚠️ Safety monitoring: Monitor for hypersensitivity reactions (rash, urticaria, anaphylaxis) — especially with first dose. Monitor for antibiotic-associated diarrhoea and Clostridioides difficile infection in prolonged courses. Monitor renal function (serum creatinine) in neonates and children receiving high-dose IV therapy.
• Minimum age: Ampicillin is approved and used from birth (including preterm neonates) — no minimum age restriction.
• Minimum weight: No minimum weight restriction — dosing is weight-based. Neonatal doses are further stratified by gestational age and postnatal age.
• Formulation suitability for children:
• • ✔ Oral suspension (125 mg/5 mL, 250 mg/5 mL) — suitable for infants and young children. Requires reconstitution with water before use.
  • ⚠️ Palatability: Ampicillin suspension has a mildly bitter taste that some children find unpalatable. Can be mixed with a small amount of water or juice immediately before administration. Do NOT pre-mix with milk or formula (may reduce stability and absorption). Flavoured commercial preparations are available from some Indian manufacturers.
  • ✔ Capsules (250 mg, 500 mg) — can be used in older children/adolescents who can swallow capsules. Capsules should NOT be opened and mixed with food — bioavailability data for opened capsule contents is limited.
  • ✔ Injection (250 mg, 500 mg, 1 g vials) — suitable for all ages including neonates.
• Age-specific pharmacokinetic differences:
• • Neonates (preterm and term): Significantly prolonged half-life (4–6 hours in preterm, 2–4 hours in term neonates) due to immature renal function and larger Vd per kg. Requires extended dosing intervals (q8h or q12h depending on gestational and postnatal age).
  • Infants and children (>1 month to 12 years): Weight-adjusted clearance approaches adult values by 1 month of age. Standard q6h dosing interval used. May require higher mg/kg doses than adults due to larger Vd per kg and faster renal clearance per kg.
  • Adolescents (≥12 years or ≥40 kg): Use adult dosing.

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NEONATAL DOSING

• ⚠️ Ampicillin + Gentamicin is the WHO-recommended and NNF India-recommended first-line empirical regimen for both EONS and LONS. This combination provides synergistic activity against GBS, Listeria, E. coli (susceptible strains), and Enterococcus.
• ⚠️ EONS vs LONS distinction: EONS (onset within first 72 hours of life) — typically vertical transmission from maternal flora (GBS, E. coli, Listeria). LONS (onset after 72 hours) — may include nosocomial organisms. In Indian NICUs with high rates of Gram-negative resistance, LONS empirical therapy may need modification (e.g., ampicillin + amikacin, or ampicillin + cefotaxime) based on unit-specific antibiogram. Always refer to local NICU antibiogram.
• ℹ️ IV administration in neonates: Administer by slow IV injection over 3–5 minutes or by IV infusion over 15–30 minutes. Never give by rapid IV push in neonates — risk of seizures with very rapid infusion of high concentrations.
• ℹ️ IM route in neonates: Acceptable when IV access is not available (e.g., in resource-limited settings, peripheral health centres before transfer). Use the anterolateral thigh as the injection site. Maximum volume per IM injection site in neonates: 0.5 mL.
• Duration of empirical therapy: If blood cultures are negative at 36–48 hours and clinical suspicion is low, discontinue ampicillin + gentamicin. ⚠️ Do NOT continue empirical antibiotics beyond 48–72 hours in culture-negative, clinically well neonates — prolonged empirical antibiotics in neonates are associated with increased risk of NEC, invasive fungal infection, and death (evidence from multiple neonatal studies).
• Indian guideline source: NNF (National Neonatology Forum) Clinical Practice Guidelines — Neonatal Sepsis (latest edition); IAP Neonatology Chapter guidelines; WHO Pocket Book of Hospital Care for Children; ICMR AMR guidelines (2019).

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Primary Indications — Paediatric (Approved / Standard in India)

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1. When to prefer: First-line empirical therapy for suspected neonatal sepsis (both EONS and LONS) as part of ampicillin + gentamicin combination. No alternative regimen is superior for EONS in most settings.
2. When NOT to use: ⛔ Do NOT use ampicillin monotherapy for neonatal sepsis — always combine with gentamicin (and/or cefotaxime for meningitis). In NICU settings with very high Gram-negative resistance (ESBL/CRE prevalence), the empirical regimen may need modification — this is a unit-level decision guided by the local antibiogram.
3. NLEM India: Ampicillin injection — included in NLEM India (2022).
4. Time to expected clinical response: Clinical improvement (reduction in apnoea, feeding improvement, normalisation of temperature instability) within 48–72 hours. Blood culture positivity usually results within 24–48 hours.
5. Treatment failure criteria: Persistent clinical deterioration at 48–72 hours, persistent positive blood cultures, development of new foci (meningitis, osteomyelitis, NEC). Escalate antibiotics based on culture results and local resistance patterns.
6. Mandatory baseline investigations: Blood culture (MANDATORY — at least 1 mL in paediatric blood culture bottle, preferably before antibiotics), complete blood count with differential, CRP (serial — at 0 and 24–48 hours), blood glucose, serum electrolytes. Lumbar puncture for CSF analysis (cell count, protein, glucose, Gram stain, culture) — recommended for all suspected LONS and when meningitis is clinically suspected. May be deferred in unstable neonates but should be done as soon as clinically feasible.
7. Specialist initiation: ⚠️ NICU/paediatrician supervision mandatory. In resource-limited peripheral settings, initial dose of ampicillin + gentamicin IM can be given by trained medical officers before referral (as per IMNCI/WHO guidelines).
8. Indian guideline source: NNF Clinical Practice Guidelines — Neonatal Sepsis; IAP Neonatology Chapter; WHO IMNCI guidelines; ICMR AMR guidelines.
9. Key safety warning: ⚠️ Ampicillin sodium injection contains sodium — relevant in fluid-restricted preterm neonates. 1 g ampicillin sodium provides ~66.7 mg (2.9 mEq) of sodium. Factor into total sodium intake calculations.
10. Common dose adjustment scenarios: Preterm neonates require extended dosing intervals (q12h) due to immature renal function. Renal impairment in neonates (e.g., perinatal asphyxia-related AKI) — further extend intervals; monitor serum creatinine.

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• GBS meningitis: 14–21 days (minimum 14 days from first sterile CSF culture)
• Listeria meningitis: 21 days minimum
• Gram-negative meningitis: 21 days minimum (often requires cefotaxime or meropenem as primary agent; ampicillin provides supplementary coverage)

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1. When to prefer: IV ampicillin for hospitalised paediatric CAP when S. pneumoniae is the likely pathogen. IAP recommends IV ampicillin or IV amoxicillin as first-line for non-severe hospitalised CAP in children.
2. When NOT to use: ⛔ Not for severe CAP requiring ICU (use ceftriaxone/cefotaxime). Not for suspected staphylococcal pneumonia (complicated pneumonia with empyema/pneumatocoeles — use cloxacillin/vancomycin). Not adequate for suspected atypical pneumonia in older children (add macrolide).
3. NLEM India: Yes.
4. Expected response: Defervescence and respiratory improvement within 48–72 hours.
5. Indian guideline source: IAP Guidelines on Management of CAP in Children (revised 2021); WHO Pocket Book of Hospital Care for Children; ICMR guidelines.

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• If the mother received adequate intrapartum GBS prophylaxis (≥1 dose of ampicillin/penicillin G ≥4 hours before delivery), the neonate can be observed clinically without routine empirical antibiotics (if well-appearing, term, and no other risk factors).
• If the mother received inadequate prophylaxis (<4 hours before delivery or no doses given), the neonate should be observed for ≥36–48 hours, and empirical antibiotics (ampicillin + gentamicin) should be started if any signs of sepsis develop.
• Indian guideline source: NNF guidelines on EONS risk assessment; IAP guidelines.

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Secondary Indications — Paediatric (Off-label, if any)

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• Evidence quality: Weak (older paediatric oncology protocols, expert consensus in resource-limited settings)
• Indian source: Select paediatric oncology unit protocols in government hospitals
• Clearly marked: OFF-LABEL
• ⚠️ Specialist only — Paediatric Oncology / Haematology supervision mandatory

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• Evidence quality: Weak (clinical practice; epiglottitis itself is rare in India post-Hib vaccination)
• Clearly marked: OFF-LABEL
• ℹ️ With widespread Hib vaccination in India (Universal Immunisation Programme since 2015), acute epiglottitis has become rare. If suspected, secure the airway FIRST — antibiotic choice is secondary to airway management.

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• Dose: 125 mg per litre of dialysis fluid (continuous dosing) OR 500 mg per litre of dialysis fluid once daily (intermittent dosing) — specialist guidance required.
• Evidence quality: Weak (extrapolated from adult ISPD guidelines and limited paediatric case series)
• Clearly marked: OFF-LABEL
• ⚠️ Specialist only — Paediatric Nephrology supervision mandatory
• No established paediatric dosing. Use only under specialist supervision.

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MISSED DOSE / DELAYED DOSE GUIDANCE

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• ℹ️ If a dose is missed by ≤3 hours: Take/give the missed dose as soon as remembered, then continue the remaining doses at the regular q6h intervals.
• ℹ️ If a dose is missed by >3 hours but ≤5 hours: Take/give the missed dose immediately, then take the next scheduled dose at the regular time (even if the interval between doses is shorter than usual — acceptable for ampicillin given its wide therapeutic window).
• ℹ️ If a dose is missed by >5 hours: Skip the missed dose entirely. Take the next dose at the regular scheduled time.
• ⛔ Never double the dose to make up for a missed dose.

• ⚠️ This dosing frequency is relevant in hospital/NICU/ICU settings where doses are nurse-administered.
• If a dose is missed by ≤2 hours: Administer immediately and continue q4h schedule.
• If a dose is missed by >2 hours: Administer immediately and reset the q4h clock from the given dose.
• ⚠️ In meningitis and endocarditis, maintaining time above MIC is critical. Missed doses can lead to treatment failure. Nursing staff should set alarms for round-the-clock q4h administration. If doses are frequently delayed, consider continuous IV infusion (off-label but pharmacologically rational).

• ℹ️ If the patient remembers a missed dose but it is almost time for the next dose (within 2 hours of next scheduled dose), skip the missed dose and take the next dose at the regular time.
• ℹ️ Remind patients: ampicillin must be taken on an empty stomach (1 hour before meals or 2 hours after meals) — even when catching up on a missed dose.

• Ampicillin does not have rebound effects or withdrawal syndrome upon stopping.
• ⚠️ However, incomplete antibiotic courses carry significant risks:
• • Treatment failure and relapse of the infection
  • Selection of resistant organisms — a major concern in the Indian AMR context
  • For serious infections (meningitis, endocarditis, sepsis): even 1–2 missed doses may allow bacterial regrowth to exceed the killing threshold
• ℹ️ If more than 2–3 consecutive doses are missed during a course for a serious infection, contact the treating physician to assess whether:
• • The course needs to be extended
  • Blood/CSF cultures need to be repeated
  • Treatment needs to be changed
• No re-titration needed — ampicillin can be safely resumed at the full dose after missed doses. There is no dose-escalation or re-introduction protocol required.
• No immunogenicity concern — not a biologic.

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RECONSTITUTION / ADMINISTRATION QUICK REFERENCE (For Nurses & Clinical Staff)

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Patient: 3 kg term neonate, Day 2 of life. Dose: 50 mg/kg = 150 mg IV q8h.

Preparation:

• 1. Reconstitute a 250 mg vial with 1.2 mL SWFI → final concentration ~167 mg/mL, final volume ~1.5 mL.
  2. Withdraw 0.9 mL (= 150 mg) from the reconstituted vial.
  3. For IV bolus: Dilute 0.9 mL in 4–5 mL NS → give slowly over 3–5 minutes.
  4. For IV infusion: Dilute 0.9 mL in 10–15 mL NS → infuse over 15–30 minutes using a syringe pump.

Discard the remaining reconstituted solution if no preservative and within the timeframe (see Stability below).

Patient: 2.5 kg term neonate. Dose: 100 mg/kg = 250 mg IV q8h.

Reconstitute a 250 mg vial with 1.2 mL SWFI. Withdraw entire volume (~1.5 mL = 250 mg). Dilute in 5–10 mL NS. Infuse over 15–30 minutes via syringe pump.

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• Normal Saline
• Heparin (in NS)
• Potassium chloride (in NS)
• Acyclovir
• Magnesium sulphate
• Calcium gluconate (check concentration)

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• ✔ Capsules: Swallow whole with a full glass of water. Do NOT crush or open capsules.
• ✔ Oral suspension: Shake well before each dose. Use a calibrated oral syringe or measuring cup (NOT a household teaspoon/tablespoon — dosing errors common in Indian practice).
• ⚠️ Take on an empty stomach — 1 hour before meals or 2 hours after meals. Food significantly reduces absorption.
• ✔ Oral suspension can be administered via nasogastric (NG) or orogastric (OG) tube. Flush tube with 5–10 mL water before and after administration.

• Adults: Inject deep IM into a large muscle mass (gluteal or deltoid). Maximum volume per IM site: 2 mL in deltoid, 5 mL in gluteal.
• Children: Inject into the anterolateral thigh (preferred in infants and young children) or deltoid (older children). Maximum volume per IM site: 0.5 mL (neonates), 1 mL (infants), 2 mL (older children).
• ℹ️ IM injection of ampicillin is painful. Adding 1% lidocaine (without adrenaline) to the reconstitution diluent reduces injection pain — however, this practice should only be done if explicitly allowed by institutional protocol and NOT for IV administration.

• ℹ️ Low-risk for tissue injury. Ampicillin is not a vesicant. If extravasation occurs, stop infusion, apply warm compress, and monitor. Significant tissue necrosis is rare but can occur with concentrated solutions.

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• Before reconstitution: Room temperature. Keep in original packaging. Protect from moisture and excessive heat.
• After reconstitution: Use promptly. If not used immediately, refrigerate and use within timeframes specified in Stability section above. Do NOT freeze reconstituted solutions.

• Capsules: Store at room temperature below 25°C. Protect from moisture.
• Dry syrup powder (before reconstitution): Store at room temperature below 25°C. Protect from moisture.
• Reconstituted oral suspension: ⚠️ Store in refrigerator (2–8°C). Discard after 7–14 days (check manufacturer’s instructions on the bottle — varies by brand). If refrigerator is unavailable, store in the coolest available location and use within 7 days. Do NOT freeze.

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RENAL ADJUSTMENT

• Consider increasing dose frequency to every 4 hours (q4h) even for non-meningeal indications
• Consider higher individual doses: 2 g q4h for serious infections
• Prolonged or continuous IV infusion (off-label but pharmacologically rational) may be considered in select ICU patients to maximise time above MIC
• If available, therapeutic drug monitoring (TDM) can guide dosing — target fT > MIC ≥ 60–70% of the dosing interval
• Indian context: ARC is under-recognised in many Indian ICUs. A measured 8-hour or 24-hour CrCl (from timed urine collection) is more accurate than calculated eGFR for detecting ARC. Consider this in young sepsis patients who are not responding despite ”adequate“ doses.

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HEPATIC ADJUSTMENT

• While ampicillin itself does not require hepatic dose adjustment, patients with severe cirrhosis (Child-Pugh C) frequently have concomitant renal impairment (hepatorenal syndrome, impaired GFR) — always check and adjust for renal function.
• Patients with cirrhosis and ascites have an expanded Vd → initial loading doses for serious infections (e.g., SBP) should NOT be reduced.
• Hypoalbuminaemia in cirrhosis: Minimal clinical impact on ampicillin (only 15–28% protein bound — low protein binding means free drug fraction is not dramatically altered by hypoalbuminaemia).
• Active metabolites: Penicilloic acid (inactive) — does not accumulate clinically in liver disease.

• Isoniazid + Rifampicin (anti-TB therapy): No specific pharmacokinetic interaction, but monitor LFTs as the anti-TB drugs are hepatotoxic. Ampicillin is occasionally co-prescribed with anti-TB drugs when concurrent bacterial infection requires treatment.
• Methotrexate: Penicillins (including ampicillin) can reduce renal clearance of methotrexate → increased risk of methotrexate toxicity (see Major Drug Interactions). Monitor LFT and methotrexate levels if co-administered.
• Valproate / Anti-retrovirals: No specific hepatotoxic interaction with ampicillin expected.

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CONTRAINDICATIONS

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CAUTIONS

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PREGNANCY

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LACTATION

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ELDERLY

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MAJOR DRUG INTERACTIONS

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MODERATE DRUG INTERACTIONS

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COMMON ADVERSE EFFECTS

• Diarrhoea and GI effects: Clearly dose-dependent. More common at higher oral doses (>2 g/day) and with prolonged courses (>7 days). Lower at standard doses of 1–2 g/day oral.
• Maculopapular rash: Not clearly dose-dependent. Occurrence is more related to host factors (EBV infection, allopurinol co-administration, hyperuricaemia) than dose.
• Phlebitis: More common with concentrated IV solutions (>30 mg/mL) and prolonged infusion through peripheral IV lines.

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SERIOUS ADVERSE EFFECTS

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MONITORING REQUIREMENTS

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• ICU patients with augmented renal clearance (ARC) — to confirm adequate levels are being achieved
• Patients with severe renal impairment on haemodialysis — to avoid accumulation
• CNS infections (meningitis) in patients with unusual PK (obese, post-neurosurgical, CSF shunt) — to confirm adequate CSF penetration
• Prolonged courses (endocarditis) in patients with fluctuating renal function

• No universally established target trough for ampicillin. The key PK/PD target is fT > MIC ≥ 40–50% of the dosing interval. For most susceptible organisms (MIC ≤ 2 mcg/mL), standard dosing achieves this target with normal renal function.
• A trough level > 2–4 times the MIC of the organism is a reasonable target for serious infections.

• The antibiotic course is completed
• For courses <7 days in patients with normal renal function: no repeat monitoring necessary unless clinical concern arises

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PATIENT COUNSELLING

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• ”Take this medicine on an empty stomach — either 1 hour before eating or 2 hours after eating. Food reduces how well the medicine works.“
• ”Take each dose with a full glass of water.“
• ”Swallow the capsule whole — do not break or chew it.“
• ”If you are taking the liquid (syrup), shake the bottle well before each dose. Use the measuring cup or syringe given with the bottle — do NOT use a household spoon (it will give the wrong amount).“
• ”Take the medicine at evenly spaced times — for example, if you take it 4 times a day, take it every 6 hours (e.g., 6 AM, 12 noon, 6 PM, 12 midnight).“
• ”Complete the full course as prescribed by your doctor, even if you feel better before the course is finished. Stopping early can allow the infection to come back, and the bacteria may become resistant to this medicine.“

• ”If you remember within 3 hours of the missed time, take the dose immediately. Then continue with your regular schedule.“
• ”If more than 3 hours have passed, skip the missed dose and take the next one at the regular time.“
• ”Never take two doses at the same time to make up for a missed dose.“

• ”You may get loose stools or diarrhoea — this is common and usually mild. Drink plenty of fluids (water, ORS, coconut water, buttermilk/chaas). If the diarrhoea is very severe, watery, bloody, or lasts more than 2 days, see your doctor.“
• ”You may feel mild nausea or stomach discomfort — this usually gets better after a few days.“
• ”Some people get a rash (red spots on the skin) after about 1–2 weeks of taking this medicine. This is usually not a dangerous allergy, but you should tell your doctor about it.“

• ⚠️ ”Difficulty breathing, swelling of the face/lips/tongue/throat, or feeling like your throat is closing — this could be a serious allergic reaction. Go to the nearest hospital immediately.“
• ⚠️ ”Severe skin rash with blisters, peeling skin, or sores in the mouth — stop the medicine and go to hospital.“
• ⚠️ ”Severe diarrhoea (bloody or watery, many times a day) with fever and stomach pain — see your doctor urgently.“
• ⚠️ ”Yellow colour of the eyes or skin (jaundice) — see your doctor.“
• ⚠️ ”Unusual bruising or bleeding — see your doctor.“
• ⚠️ ”Fits (seizures/convulsions) — go to hospital.“

• ”Do not take this medicine with food — it must be taken on an empty stomach.“
• ”There is no specific restriction on alcohol, but alcohol may worsen nausea and stomach discomfort. It is best to avoid alcohol while you are unwell with an infection.“
• ”Do not take any other medicines (including medicines bought from the chemist without prescription, and any Ayurvedic or herbal medicines) without telling your doctor — some medicines may interact.“

• Capsules: ”Store at room temperature in a cool, dry place. Keep away from moisture and direct sunlight. Keep out of reach of children.“
• Reconstituted oral suspension (liquid): ”After the chemist adds water to the powder, store the bottle in the fridge. If you do not have a fridge, keep it in the coolest part of your house — away from the kitchen, stove, and windows. Use within 7 days (check the label). After 7–14 days, throw away any leftover liquid.“
• ℹ️ Indian hot climate note: ”In summer, the medicine may spoil faster if left at room temperature. Try to keep it cool. If the liquid looks or smells different, do not use it.“

• ”This medicine is for a specific course to treat your infection — it is NOT a long-term medicine.“
• ”Your doctor will tell you how many days to take it. Please complete the full course.“
• ”Do NOT stop early even if you feel better — the infection may come back and be harder to treat.“

• ”Come back to your doctor if you are not feeling better after 3 days of taking this medicine.“
• ”Come back for any blood tests or check-ups your doctor has asked for.“
• ”If you are taking this medicine for a long time (more than 2 weeks), your doctor may ask for blood tests to check your kidneys and blood counts.“

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• ✔ How to give the correct dose — use the measuring cup or syringe provided, NOT a household spoon.
• ✔ Timing — every 6 hours, on an empty stomach. Set alarms on a phone if needed.
• ✔ Shaking the suspension bottle well before each dose.
• ✔ Storing the liquid in the fridge (or coolest spot if no fridge).
• ✔ Warning signs to watch for in the child or elderly patient: difficulty breathing, swelling of face, severe rash, severe diarrhoea, fits (seizures), reduced urine output, drowsiness/confusion, refusing feeds. Bring to hospital immediately if any of these occur.
• ✔ Completing the full course — even if the child seems well.
• ✔ Do NOT share this antibiotic with another family member or save leftover doses for future illness.

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BRANDS AVAILABLE IN INDIA

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PRICE RANGE (INR)

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• Oral ampicillin is comparable in cost to oral amoxicillin (also NLEM-listed). Amoxicillin is preferred for most oral indications due to better bioavailability — the cost difference is negligible.
• Ampicillin-sulbactam injection (1.5 g vial) costs approximately ₹40–120 per vial (private), ₹20–50 (Jan Aushadhi) — modestly more expensive than plain ampicillin injection but provides beta-lactamase coverage.

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CLINICAL PEARLS

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VERSION

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REFERENCES

1. CDSCO Product Insert — Ampicillin Capsules and Ampicillin Sodium Injection (multiple manufacturers; representative insert from Cadila Healthcare Ltd / Zydus Cadila). CDSCO-approved labelling for indications, dosing, contraindications, and adverse effects.
2. Indian Pharmacopoeia 2022 — Indian Pharmacopoeia Commission. Monograph: Ampicillin (anhydrous), Ampicillin trihydrate, Ampicillin sodium. Drug standards, identification, assay.
3. National List of Essential Medicines (NLEM) India, 2022 — Ministry of Health and Family Welfare, Government of India. Ampicillin listed under Section 6.2 (Antibacterials — Beta-lactam medicines).
4. National Formulary of India, 6th Edition (2021) — Indian Pharmacopoeia Commission. Ampicillin monograph: indications, dosing, adverse effects, pharmacokinetics, drug interactions.
5. ICMR Treatment Guidelines for Antimicrobial Use in Common Syndromes, 2019 — Indian Council of Medical Research. Guidance on empirical antibiotic selection for common infections including UTI, pneumonia, meningitis, enteric fever, and neonatal sepsis. Resistance data and recommendations for India-specific antibiotic stewardship.
6. API Textbook of Medicine, 11th Edition — Association of Physicians of India. Chapters on: Bacterial Meningitis, Infective Endocarditis, Community-Acquired Pneumonia, Urinary Tract Infections, Enteric Fever, Spontaneous Bacterial Peritonitis, Peritonitis, Obstetric Infections.
7. IAP (Indian Academy of Pediatrics) Guidelines:
8. • IAP Guidelines on Management of Community-Acquired Pneumonia in Children (revised 2021).
   • IAP Guidelines on Urinary Tract Infections in Children.
   • IAP Neonatology Chapter — Guidelines on Neonatal Sepsis.
9. NNF (National Neonatology Forum of India) Clinical Practice Guidelines — Neonatal Sepsis: Diagnosis and Management (latest edition). Empirical antibiotic regimens for EONS and LONS, neonatal meningitis dosing.
10. WHO Pocket Book of Hospital Care for Children, 2nd Edition (2013) — World Health Organization. Neonatal and paediatric dosing for ampicillin + gentamicin. Integrated Management of Childhood Illness (IMNCI) guidelines.
11. FOGSI (Federation of Obstetric and Gynaecological Societies of India) Guidelines — Intrapartum GBS prophylaxis, chorioamnionitis management, PPROM latency antibiotics, postpartum endometritis.
12. Goodman & Gilman’s The Pharmacological Basis of Therapeutics, 14th Edition (2023) — Brunton LL, Knollmann BC (editors). Chapter: Penicillins, Cephalosporins, and Other β-Lactam Antibiotics. Pharmacology, mechanism of action, PK/PD principles of beta-lactams, time-dependent killing, spectrum of activity.
13. Harrison’s Principles of Internal Medicine, 21st Edition (2022) — Jameson JL, Fauci AS, Kasper DL, et al. (editors). Chapters: Treatment of Bacterial Infections, Meningitis, Infective Endocarditis, Pneumonia, UTI, Enteric Fever, Intra-abdominal Infections.
14. AIIMS Treatment Guidelines / Protocols — All India Institute of Medical Sciences, New Delhi. Referenced for: Empirical meningitis management, Infective Endocarditis treatment protocols, Neonatal sepsis management, Surgical infectious disease protocols (intra-abdominal infections).
15. NPPA (National Pharmaceutical Pricing Authority) — Drug Price Control Order (DPCO) — Ceiling price notifications for ampicillin formulations. Available at nppaindia.nic.in.
16. PMBJP (Pradhan Mantri Bhartiya Janaushadhi Pariyojana) — Product catalogue and pricing. Available at janaushadhi.gov.in.
17. CDSCO Banned Drugs List — Gazette of India notifications on banned/restricted fixed-dose combinations. Reviewed to confirm no ampicillin single-ingredient or approved FDC ban status.
18. PvPI (Pharmacovigilance Programme of India) — ADR reporting guidelines and mechanism. Central Drugs Standard Control Organisation. Available at cdsco.gov.in.
19. Mercer BM, et al. (1997) — ”Antibiotic therapy for reduction of infant morbidity after preterm premature rupture of the membranes.“ JAMA; 278(12):989–995. (Referenced for PPROM latency antibiotic regimen — off-label indication.)
20. ORACLE Collaborative Group (2001) — Kenyon SL, et al. ”Broad-spectrum antibiotics for preterm, prelabour rupture of fetal membranes: the ORACLE I randomised trial.“ Lancet; 357(9261):979–988. (Referenced for PPROM latency antibiotic evidence and the warning against amoxicillin-clavulanate in PPROM.)
21. Fernandez-Hidalgo N, et al. (2013) — ”Ampicillin plus ceftriaxone is as effective as ampicillin plus gentamicin for treating Enterococcus faecalis infective endocarditis.“ Clin Infect Dis; 56(9):1261–1268. (Referenced for the ampicillin + ceftriaxone regimen for Enterococcal IE — off-label combination evidence.)
22. Indian Paediatric Nephrology Group (IPNG) Guidelines — UTI management in children. Referenced for paediatric UTI evaluation and treatment.
23. ISPD (International Society for Peritoneal Dialysis) Guidelines — PD-related peritonitis prevention and treatment (2022 update). Referenced for intraperitoneal ampicillin dosing in PD peritonitis.

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