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Fetal and Neonatal Care
Neonatal sepsis: risk factors, evaluation, and empiric treatment
Clinical Overview and When to Suspect
Neonatal sepsis is a systemic bacterial infection occurring in the first 28 days of life, categorized by timing of onset:
Early-onset sepsis (EOS): ≤72 hours of life (some definitions use ≤7 days) — acquired from vertical/intrapartum transmission
Late-onset sepsis (LOS): >72 hours to 28 days — acquired from environmental/nosocomial or community sources
Neonatal sepsis is a leading cause of neonatal morbidity and mortality, especially in preterm infants
Clinical signs are NONSPECIFIC — temperature instability (hypothermia more common than fever in neonates), tachypnea, apnea, lethargy, poor feeding, irritability, tachycardia, hypotension, mottling, prolonged capillary refill
Board pearl: Neonates may present with hypothermia rather than fever as the primary temperature abnormality — this is especially true in preterm infants who lack the thermoregulatory capacity to mount a febrile response
EOS must be considered in ANY neonate with respiratory distress, especially if risk factors are present
The threshold to evaluate should be LOW — neonatal sepsis can progress to fulminant shock and death within hours
History — Maternal and Perinatal Risk Factors for EOS
The prenatal/intrapartum history is critical for EOS risk stratification:
Maternal risk factors:
Maternal GBS colonization (rectovaginal culture at 35–37 weeks) — GBS is the #1 cause of EOS in term infants
Inadequate intrapartum antibiotic prophylaxis (IAP): <4 hours of appropriate IV antibiotics before delivery
Prolonged rupture of membranes (PROM) ≥18 hours
Chorioamnionitis/intraamniotic infection (maternal fever ≥38.0°C/100.4°F, uterine tenderness, foul-smelling amniotic fluid, maternal/fetal tachycardia)
Preterm labor (<37 weeks) — prematurity itself is the single greatest risk factor for EOS
Prior infant with invasive GBS disease
GBS bacteriuria during current pregnancy
Board pearl: Chorioamnionitis is the strongest independent risk factor for EOS — even with appropriate IAP, neonates born to mothers with chorioamnionitis require enhanced observation or full sepsis evaluation depending on clinical appearance
Unknown GBS status at delivery with risk factors (preterm, ROM ≥18 hr, maternal fever) → treat as positive
Physical Exam — The Septic Neonate
Neonatal sepsis presents with subtle, nonspecific signs — a high index of suspicion is essential:
Temperature instability: Hypothermia (<36.5°C) is a red flag in neonates; fever (>38.0°C) also concerning but less common in preterms
Respiratory: Tachypnea, grunting, nasal flaring, retractions, apnea (especially in preterm infants) — may mimic RDS, TTN, or pneumonia
Cardiovascular: Tachycardia, poor perfusion, prolonged capillary refill >3 seconds, hypotension (late/ominous sign), mottled/gray skin
Neurologic: Lethargy, hypotonia, poor feeding, weak cry, irritability, seizures (consider meningitis)
GI: Feeding intolerance, abdominal distension, vomiting, ileus
Skin: Petechiae, purpura (late — suggests DIC), jaundice (may indicate hepatic involvement or hemolysis from infection)
Board pearl: A "well-appearing" neonate can still be septic — clinical appearance alone cannot exclude serious bacterial infection, which is why serial observation over time (not a single exam) is the standard
Key distinction: Pneumonia as a presentation of EOS — GBS pneumonia can be radiographically indistinguishable from RDS in preterm infants
Diagnostic Workup — EOS Evaluation
The evaluation depends on clinical status, gestational age, and risk factors:
Standard EOS workup ("full sepsis evaluation"):
— WBC <5,000/μL or ANC <1,000/μL → concerning for sepsis
— I:T ratio >0.2 → ↑ likelihood of infection
— Board pearl: CBC has poor positive predictive value (~30%) but a normal I:T ratio has reasonable negative predictive value; CBC obtained <4 hours after birth has even lower sensitivity
— Perform if blood culture positive, clinical signs of meningitis, or clinical deterioration
— LP may be deferred in a well-appearing term infant being evaluated solely for risk factors, but MUST be done if antibiotics will continue >48 hours
Blood culture — GOLD STANDARD; obtain before antibiotics; minimum 1 mL in a single aerobic bottle (neonatal bottle); two-site cultures ideal but often impractical
CBC with differential — WBC, absolute neutrophil count (ANC), immature-to-total (I:T) neutrophil ratio, platelet count
Lumbar puncture (LP) with CSF analysis — cell count, protein, glucose, Gram stain, culture
Chest X-ray if respiratory symptoms present
Urinalysis/urine culture — NOT part of EOS workup (UTI extremely rare <72 hours); essential for LOS evaluation
Diagnostic Workup — Inflammatory Markers and Risk Calculators
Inflammatory biomarkers:
— Single CRP has limited sensitivity for EOS; serial normal values help guide de-escalation (negative predictive value ~99% with two normal CRPs 24 hours apart)
Neonatal EOS risk calculator (Kaiser/Puopolo):
C-reactive protein (CRP): Rises 6–8 hours after infection onset; serial CRPs at 24–48 hours ↑ sensitivity
Procalcitonin (PCT): Rises earlier than CRP (2–4 hours); physiologic rise in first 24–48 hours of life limits utility in the immediate postnatal period for EOS
Neither CRP nor PCT alone should be used to diagnose or exclude EOS
Multivariate model using maternal risk factors (GBS status, highest intrapartum temperature, ROM duration, gestational age, type of IAP) + clinical exam
Generates sepsis probability per 1,000 live births → guides management: routine care vs. enhanced vitals vs. blood culture + empiric antibiotics
Board pearl: The EOS risk calculator applies ONLY to infants ≥34 weeks GA born in the setting of adequate obstetric care — it does NOT apply to preterm <34 weeks or infants with congenital anomalies
Many institutions now use this calculator to reduce unnecessary antibiotic exposure and mother-infant separation
Management — Empiric Antibiotic Therapy for EOS
When EOS is suspected, empiric antibiotics should be started IMMEDIATELY after cultures are obtained — do not delay for lab results:
First-line empiric regimen for EOS:
— Ampicillin: covers GBS, Listeria monocytogenes, Enterococcus, and most E. coli
— Gentamicin: covers gram-negative organisms (E. coli, Klebsiella) and provides synergy with ampicillin against GBS and Listeria
— Ampicillin: 50 mg/kg/dose (100 mg/kg/dose for meningitis) — frequency depends on GA and postnatal age
— Gentamicin: 4–5 mg/kg/dose q24–48h depending on GA; monitor trough levels
Ampicillin + Gentamicin — this is the standard of care
Dosing is weight- and gestational-age-dependent:
Board pearl: Cefotaxime is NOT first-line for EOS — it does not cover Listeria and promotes resistant organisms; reserve for confirmed gram-negative meningitis
Duration: If blood cultures negative at 36–48 hours AND infant is clinically well → STOP antibiotics
Positive blood culture → treat based on organism and sensitivities (GBS: 10 days for bacteremia, 14–21 days for meningitis)
Management — Empiric Therapy for LOS and Special Scenarios
Late-onset sepsis (LOS) empiric regimen:
— Vancomycin covers coagulase-negative staphylococci (CoNS) and MRSA — the most common NICU-acquired pathogens
— Adjust based on local antibiograms
When to broaden or change antibiotics:
Community-acquired LOS: Ampicillin + Gentamicin (same as EOS) remains appropriate
Nosocomial/NICU-acquired LOS: Vancomycin + Gentamicin (or Vancomycin + a third-generation cephalosporin)
If concern for gram-negative meningitis → add cefotaxime (or cefepime) to provide better CNS penetration than gentamicin
Clinical deterioration on standard therapy
HSV suspected (vesicles, seizures, hepatitis, maternal genital herpes) → add IV acyclovir 20 mg/kg/dose q8h
Fungal sepsis (preterm <1000 g, prior broad-spectrum antibiotics, central lines, TPN) → add amphotericin B or fluconazole
Board pearl: LOS with an indwelling central line → obtain cultures from the line AND peripherally; consider line removal for Candida, S. aureus, or persistent bacteremia >48 hours on appropriate antibiotics
Management — Duration, De-escalation, and Antibiotic Stewardship
Appropriate antibiotic stewardship in neonates is critical to minimize harm:
— Prolonged "rule-out" antibiotics (>48 hours with negative cultures) ↑ risk of NEC, invasive candidiasis, antibiotic resistance, and altered gut microbiome
Rule of 36–48 hours: If blood cultures remain negative at 36–48 hours AND the neonate is well-appearing → discontinue antibiotics
Culture-positive bacteremia without meningitis: 10 days of targeted antibiotics
Bacterial meningitis: GBS → 14–21 days IV antibiotics; gram-negative → ≥21 days; repeat LP at 24–48 hours to document CSF sterilization for gram-negative meningitis
Board pearl: A "traumatic tap" with RBCs in CSF does NOT reliably predict meningitis — if clinical suspicion is high and CSF is difficult to interpret, treat for meningitis pending culture results; consider repeat LP in 24–48 hours
Serial CRP trending downward supports clinical decision to narrow or stop antibiotics
Gentamicin levels: Obtain trough before 3rd dose; target trough <1 μg/mL to avoid oto/nephrotoxicity
Transition to oral antibiotics is generally NOT recommended for neonatal sepsis/meningitis — complete IV course
Age-Specific Considerations — Term vs. Preterm EOS
Term and late-preterm (≥35 weeks):
Preterm (<34 weeks):
GBS is the most common EOS pathogen, followed by E. coli
EOS risk calculator can guide management — many well-appearing term infants with maternal risk factors may be observed with serial vitals rather than empirically treated
Enhanced observation: Vital signs q4h for 24–48 hours in the newborn nursery with nursing assessments for clinical change
E. coli is the #1 cause of EOS in very-low-birth-weight (VLBW, <1500 g) infants
Virtually all preterm infants <34 weeks born with risk factors receive empiric antibiotics until cultures are negative — clinical observation alone is insufficient due to subtle presentation and high mortality risk
Immature immune system → quantitative and qualitative deficiencies in neutrophils, complement, immunoglobulins (IgG transplacental transfer occurs mainly after 32 weeks → preterm infants are relatively immunoglobulin-deficient)
Board pearl: Maternal IgG crosses the placenta via FcRn receptor starting ~13 weeks, with the majority transferred in the third trimester → infants born <32 weeks have critically low IgG levels, contributing to infection susceptibility
Preterm infants may present with apnea as the ONLY sign of sepsis
Age-Specific Considerations — LOS by Setting
NICU-acquired (nosocomial) LOS:
Community-acquired LOS (well-infant nursery or post-discharge):
Highest risk: VLBW infants with prolonged NICU stays, central venous catheters, TPN, endotracheal tubes
#1 pathogen: Coagulase-negative staphylococci (CoNS, especially S. epidermidis) — often associated with central lines
Other pathogens: S. aureus (including MRSA), Enterococcus, gram-negative rods (Klebsiella, Pseudomonas, Serratia, Enterobacter), Candida spp.
Candida risk factors: extreme prematurity (<1000 g), broad-spectrum antibiotics, TPN, central lines, H₂ blockers
GBS remains important (late-onset GBS disease peaks at 1–3 months; presents as bacteremia, meningitis, or rarely cellulitis/osteomyelitis)
E. coli, Listeria (rare), and other gram-negatives
Board pearl: Late-onset GBS disease is NOT prevented by intrapartum antibiotic prophylaxis — IAP only reduces early-onset GBS. A neonate presenting at 2–4 weeks with fever and meningitis → GBS remains a major concern regardless of IAP history
HSV must always be considered in the 1–6 week age group, especially with CSF pleocytosis, seizures, vesicular rash, or elevated transaminases
Complications and Emergencies — Septic Shock
Neonatal septic shock is a medical emergency with high mortality:
— IV/IO access STAT → NS or LR bolus 10 mL/kg over 5–10 minutes → reassess → repeat up to 40–60 mL/kg in first hour if needed
— Empiric antibiotics within 1 hour of recognition
— Correct hypoglycemia (D10W 2 mL/kg bolus), hypocalcemia (Ca²⁺ gluconate 100 mg/kg IV slow push with cardiac monitoring)
Recognition: Tachycardia, poor perfusion, altered mental status, oliguria; hypotension is a LATE finding in neonates (cold shock with ↑ SVR is more common than warm shock)
Initial resuscitation (first 60 minutes — the "golden hour"):
Vasopressors: If fluid-refractory shock → dopamine (first-line) 5–20 μg/kg/min → if refractory → epinephrine (cold shock) or norepinephrine (warm shock)
Board pearl: Neonates with septic shock may have relative adrenal insufficiency → consider stress-dose hydrocortisone (1–2 mg/kg IV) for catecholamine-resistant shock
Coagulopathy/DIC → petechiae, oozing from puncture sites, ↑ PT/INR, ↑ PTT, ↓ fibrinogen, ↑ D-dimer → administer FFP, cryoprecipitate, platelets as needed
Transfer to NICU for invasive monitoring, mechanical ventilation, and inotropic support
Complications — Meningitis and Long-Term Sequelae
Neonatal meningitis:
Occurs in ~25% of neonates with EOS bacteremia; higher rates with E. coli and GBS type III (LOS meningitis pathogen)
CSF findings in bacterial meningitis: ↑ WBC (may be >1,000/μL but can be low in preterms), ↑ protein (>150 mg/dL in term, >200 mg/dL in preterm), ↓ glucose (<40 mg/dL or CSF:serum glucose ratio <0.6), positive Gram stain/culture
Board pearl: Normal neonatal CSF has higher WBC and protein than older children — term neonates: up to 22 WBC/μL and protein up to 150 mg/dL; preterm: up to 29 WBC/μL and protein up to 170 mg/dL → know your neonatal normal ranges
Complications of neonatal meningitis: cerebral abscess, ventriculitis, hydrocephalus, SIADH, subdural empyema, sensorineural hearing loss, cerebral palsy, developmental delay
Gram-negative meningitis (especially E. coli K1) → higher mortality (~30%), higher complication rate → repeat LP at 48 hours to confirm sterilization; if CSF not sterile → reassess antibiotics, consider imaging for abscess/ventriculitis
All survivors of neonatal meningitis need audiology evaluation (ABR) before discharge and long-term neurodevelopmental follow-up
Key Differentials — EOS Mimics
Many neonatal conditions mimic sepsis and must be considered:
Transient tachypnea of the newborn (TTN): Tachypnea within hours of birth, especially after cesarean delivery; CXR shows perihilar streaking/fluid in fissures; resolves 24–72 hours — but start antibiotics until cultures negative if clinical concern exists
Respiratory distress syndrome (RDS): Preterm infant with progressive respiratory distress, ground-glass CXR, air bronchograms — radiographically indistinguishable from GBS pneumonia in preterms
Congenital heart disease (CHD): Cyanosis, tachypnea, poor perfusion — duct-dependent lesions present when PDA closes (day 2–7); hyperoxia test helps distinguish cardiac from pulmonary disease
Inborn errors of metabolism (IEM): Present in first days with lethargy, poor feeding, vomiting, metabolic acidosis, hyperammonemia → obtain ammonia, lactate, blood gas, urine organic acids
Neonatal HSV: Vesicles (may be absent), seizures, hepatitis (↑ AST/ALT), CSF pleocytosis, thrombocytopenia → send HSV PCR from blood and CSF; start acyclovir empirically if suspected
Board pearl: The classic board trap — neonate presenting at day 7–14 with seizures, CSF pleocytosis, and liver dysfunction → think HSV, not just bacterial meningitis → always send HSV PCR and start acyclovir
Key Differentials — Distinguishing EOS from LOS and Non-Infectious Causes
EOS vs. LOS — key distinguishing features:
Non-infectious mimics of sepsis to always consider:
Timing: EOS ≤72 hours; LOS >72 hours
Pathogens: EOS → GBS, E. coli; LOS → CoNS, S. aureus, gram-negatives, Candida (NICU); GBS, E. coli (community)
Acquisition: EOS → vertical (birth canal); LOS → horizontal (hands, equipment, breast milk for some organisms)
Meningitis more common in LOS (~30% vs. ~25% in EOS)
Congenital adrenal hyperplasia (CAH): salt-wasting crisis at 1–2 weeks → hyponatremia, hyperkalemia, hypotension, virilized female → check 17-hydroxyprogesterone
Intestinal obstruction: bilious vomiting, distension → think malrotation/volvulus (surgical emergency)
Non-accidental trauma: irritability, lethargy, bulging fontanelle → consider head CT if mechanism unclear
Board pearl: Any neonate who "looks septic" with negative cultures at 48 hours → broaden your differential to include IEM (check ammonia, lactate, organic acids), CHD (echocardiogram), HSV (PCR), and CAH (17-OHP) — do NOT simply stop thinking after ruling out bacteria
Prevention — GBS Prophylaxis and IAP
Prevention of EOS centers on intrapartum antibiotic prophylaxis (IAP) for GBS:
Who gets IAP:
Adequate IAP:
Impact:
Positive GBS rectovaginal culture at 36 0/7–37 6/7 weeks
GBS bacteriuria at any time during current pregnancy (indicates heavy colonization)
Previous infant with invasive GBS disease
Unknown GBS status at labor onset WITH any of: <37 weeks, ROM ≥18 hours, intrapartum temperature ≥38.0°C
GBS-positive in a prior pregnancy alone is NOT an indication — must rescreen
Penicillin G (preferred) or Ampicillin IV ≥4 hours before delivery
Penicillin-allergic: Cefazolin (low risk anaphylaxis) or Clindamycin/Vancomycin (high risk anaphylaxis, based on susceptibility)
Board pearl: IAP is considered INADEQUATE if: <4 hours of appropriate IV antibiotic before delivery, oral antibiotics only, or no antibiotics given → affects neonatal management algorithm
IAP has reduced EOS from GBS by ~80% since implementation in the 1990s
IAP does NOT prevent late-onset GBS disease
IAP does NOT prevent E. coli sepsis (in fact, ampicillin-resistant E. coli EOS has increased in VLBW infants)
Screening, Follow-Up, and Post-Discharge Considerations
Newborn nursery screening for EOS risk:
Post-discharge follow-up after confirmed sepsis:
Review ALL maternal prenatal records: GBS status, serologies, intrapartum events
Categorical approach (traditional): Assigns neonates to risk categories based on maternal factors and clinical appearance → determines workup
Multivariate approach (EOS calculator): Integrates multiple risk factors quantitatively → individualized risk → more targeted management, fewer unnecessary antibiotics and blood draws
Serial clinical observation: Well-appearing term infants with risk factors may be monitored with structured vitals (temp, HR, RR, feeding quality) q4h for 24–48 hours
Ensure completion of full antibiotic course (especially if transitioned from NICU to continued IV therapy)
Hearing screen (ABR) — especially after meningitis or aminoglycoside exposure
Neurodevelopmental surveillance: monitor milestones at all well-child visits
Board pearl: Infants who had gram-negative meningitis need head imaging (MRI or US) before discharge to evaluate for hydrocephalus, abscess, or parenchymal injury → repeat imaging as indicated
Growth monitoring — prolonged sepsis/NICU stay may impact growth trajectory
Repeat renal function if prolonged aminoglycoside course used
Family Counseling and Psychosocial Considerations
Parents of a neonate undergoing sepsis evaluation experience significant anxiety — the word "sepsis" is frightening; explain clearly: "We are doing blood tests and giving antibiotics as a precaution because infections in newborns can be hard to detect early"
Emphasize that MOST sepsis evaluations are negative — >95% of neonates evaluated for EOS do not have confirmed infection
If antibiotics are started, explain the plan: "If blood cultures are negative in 36–48 hours and your baby looks well, we will stop antibiotics"
Mother–infant separation for evaluation/treatment disrupts bonding and breastfeeding → facilitate skin-to-skin contact and breastfeeding whenever medically safe; consider bedside evaluation when possible
For confirmed sepsis/meningitis → provide honest, compassionate prognostic counseling; for meningitis, discuss potential long-term neurodevelopmental outcomes and the importance of follow-up
Board pearl: Unnecessary prolonged antibiotic use has real consequences — altered neonatal microbiome, ↑ risk of NEC (in preterms), ↑ antibiotic resistance, longer hospitalization, ↑ parental anxiety → counsel families that STOPPING antibiotics when cultures are negative is the RIGHT decision
GBS-positive mothers should be reassured that IAP significantly reduces EOS risk and that being GBS-colonized is normal (present in ~25% of women)
High-Yield Associations and Rapid-Fire Board Facts
GBS: #1 EOS pathogen in term infants; #1 LOS meningitis pathogen; late-onset peaks 1–3 months
E. coli K1: #1 EOS pathogen in VLBW infants; most common cause of gram-negative neonatal meningitis; ↑ ampicillin resistance
Listeria monocytogenes: Acquired from maternal ingestion of unpasteurized dairy/deli meats; treated with ampicillin (cephalosporins do NOT cover Listeria) — this is a classic board question
CoNS: #1 cause of nosocomial LOS in NICU; associated with central lines; low virulence; treat with vancomycin
Candida: #1 fungal pathogen in NICU; risk ↑ with birth weight <1000 g, central lines, TPN, broad-spectrum antibiotics; can cause fungal balls in kidneys → renal US
HSV: Think of it when sepsis picture + liver dysfunction + seizures + CSF pleocytosis ± vesicles; ADD acyclovir; do NOT wait for vesicles
Normal neonatal CSF WBC: up to ~22/μL (term), ~29/μL (preterm); protein: up to 150 (term), 170 (preterm) mg/dL
Board pearl: Cefotaxime does NOT cover Listeria and does NOT cover Enterococcus → ampicillin is ALWAYS part of the neonatal empiric regimen
Chorioamnionitis → strongest risk factor for EOS → enhanced evaluation regardless of clinical appearance
One-Line Recap
Neonatal sepsis — classified as early-onset (≤72 hours; vertical transmission; GBS #1 in term, E. coli #1 in VLBW; empiric ampicillin + gentamicin; risk-stratified by maternal factors including chorioamnionitis, GBS status, ROM duration, and prematurity using categorical or calculator-based approaches) or late-onset (>72 hours; nosocomial CoNS #1 in NICU → vancomycin + gentamicin; community-acquired GBS/E. coli → ampicillin + gentamicin) — presents with nonspecific signs (temperature instability, respiratory distress, apnea, lethargy, poor feeding), requires blood culture before antibiotics, LP when meningitis suspected or culture positive, and de-escalation at 36–48 hours if cultures negative; always consider HSV (add acyclovir if vesicles, seizures, hepatitis, or CSF pleocytosis), monitor for complications (septic shock → fluid resuscitation + vasopressors; meningitis → prolonged IV therapy with repeat LP for gram-negatives; DIC), and remember that prevention through adequate GBS IAP (≥4 hours IV penicillin) has reduced EOS dramatically but does NOT prevent late-onset GBS or E. coli disease.
Board Question Stem Patterns
Term neonate, 6 hours old, tachypneic, grunting; mother had fever 39°C in labor, ROM 22 hours → next step: blood culture + CBC → start ampicillin + gentamicin → diagnosis: suspected EOS with chorioamnionitis
Well-appearing term neonate, GBS-positive mother received penicillin 2 hours before delivery → management: enhanced observation with serial vitals q4h for ≥36 hours (or use EOS calculator) — do NOT need empiric antibiotics if well-appearing
Preterm 28-week infant in NICU, day 14 of life, develops apnea, temperature instability, ↑ glucose → next step: blood culture, CBC, CRP, LP → start vancomycin + gentamicin → most likely pathogen: CoNS
Neonate at day 10, irritable, vesicular rash, CSF with 80 WBC (lymphocyte-predominant), elevated AST/ALT → diagnosis: neonatal HSV → next step: HSV PCR (blood and CSF) + IV acyclovir 20 mg/kg/dose q8h IMMEDIATELY
Neonate with confirmed GBS bacteremia, LP shows 450 WBC, protein 280 mg/dL, glucose 15 mg/dL → diagnosis: GBS meningitis → duration of antibiotics: 14–21 days IV penicillin or ampicillin
Blood culture positive for gram-negative rod in 3-day-old → next step: LP if not already done → CSF culture + adjust antibiotics → if meningitis confirmed → treat ≥21 days, repeat LP at 48 hours
VLBW infant day 21, on TPN via central line, thrombocytopenia, blood culture grows yeast → pathogen: Candida → management: remove central line + amphotericin B; obtain renal US and ophthalmologic exam
Mother with no prenatal care, term infant at 4 hours with tachypnea → what do you do? → treat as unknown GBS, obtain cultures, start ampicillin + gentamicin; also check maternal HBsAg, HIV, RPR
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