Neonatal sepsis

Neonatal sepsis
Classification and external resources
ICD-10	P36
ICD-9	771.81
eMedicine	article/978352

In common clinical usage, neonatal sepsis specifically refers to the presence of a bacterial blood stream infection (BSI) (such as meningitis, pneumonia, pyelonephritis, or gastroenteritis) in the setting of fever. Criteria with regards to hemodynamic compromise or respiratory failure are not useful clinically because these symptoms often do not arise in neonates until death is imminent and unpreventable.

It is difficult to clinically exclude sepsis in newborns less than 90 days old that have fever (defined as a temperature > 38°C (100.4°F). Except in the case of obvious acute viral bronchiolitis, the current practice in newborns less than 30 days old is to perform a complete workup including complete blood count with differential, blood culture, urinalysis, urine culture, and cerebrospinal fluid(CSF) studies and CSF culture, admit the newborn to the hospital, and treat empirically for serious bacterial infection for at least 48 hours until cultures are demonstrated to show no growth. Attempts have been made to see whether it is possible to risk stratify newborns in order to decide if a newborn can be safely monitored at home without treatment despite having a fever. One such attempt is the Rochester criteria.

Risk factors

A study performed at Strong Memorial Hospital in Rochester, New York, showed that infants ≤ 60 days old meeting the following criteria were at low-risk for having a serious bacterial illness^[1]:

• generally well-appearing
• previously healthy
  • full term (at ≥37 weeks gestation)
  • no antibiotics perinatally
  • no unexplained hyperbilirubinemia that required treatment
  • no antibiotics since discharge
  • no hospitalizations
  • no chronic illness
  • discharged at the same time or before the mother
• no evidence of skin, soft tissue, bone, joint, or ear infection
• WBC count 5,000-15,000/mm³
• absolute band count ≤ 1,500/mm³
• urine WBC count ≤ 10 per high power field (hpf)
• stool WBC count ≤ 5 per high power field (hpf) only in infants with diarrhea

Those meeting these criteria likely do not require a lumbar puncture, and are felt to be safe for discharge home without antibiotic treatment, or with a single dose of intramuscular antibiotics, but will still require close outpatient follow-up.

Diagnosis

Neonatal sepsis screening:

1. DLC showing increased numbers of polymorphs.
2. DLC: band cells > 20%.
3. increased haptoglobins.
4. micro ESR (Erythrocyte Sedimentation Rate) titer > 55mm.
5. gastric aspirate showing > 5 polymorphs per high power field.
6. newborn CSF (CerebroSpinal Fluid) screen: showing increased cells and proteins.
7. suggestive history of chorioamnionitis, PROM (Premature Rupture Of Membranes), etc...

Treatment

Note that, in neonates, sepsis is difficult to diagnose clinically. They may be relatively asymptomatic until hemodynamic and respiratory collapse is imminent, so, if there is even a remote suspicion of sepsis, they are frequently treated with antibiotics empirically until cultures are sufficiently proven to be negative. In addition to fluid resuscitation and supportive care, a common antibiotic regimen in infants with suspected sepsis is a beta-lactam antibiotic (usually ampicillin) in combination with an aminoglycoside (usually gentamicin) or a third-generation cephalosporin (usually cefotaxime—ceftriaxone is generally avoided in neonates due to the theoretical risk of kernicterus.) The organisms which are targeted are species that predominate in the female genitourinary tract and to which neonates are especially vulnerable to, specifically Group B Streptococcus, Escherichia coli, and Listeria monocytogenes (This is the main rationale for using ampicillin versus other beta-lactams.) Of course, neonates are also vulnerable to other common pathogens that can cause meningitis and bacteremia such as Streptococcus pneumoniae and Neisseria meningitidis. Although uncommon, if anaerobic species are suspected (such as in cases where necrotizing enterocolitis or intestinal perforation is a concern, clindamycin is often added.

Granulocyte-macrophage colony stimulating factor (GM-CSF) is often used in neonatal sepsis, however a recent study found that, while GM-CSF corrects neutropenia if present, it has no effect on reducing sepsis or improving survival. ^[2]

References

1. ^ Dagan R, Powell KR, Hall CB, Menegus MA (Dec 1985). "Identification of infants unlikely to have serious bacterial infection although hospitalized for suspected sepsis". J. Pediatr. 107 (6): 855–60. doi:10.1016/S0022-3476(85)80175-X. PMID 4067741. http://www.jpeds.com/article/S0022-3476(85)80175-X/abstract. 
2. ^ Carr R, Brocklehurst P, Doré CJ, Modi N (January 2009). "Granulocyte-macrophage colony stimulating factor administered as prophylaxis for reduction of sepsis in extremely preterm, small for gestational age neonates (the PROGRAMS trial): a single-blind, multicentre, randomised controlled trial". Lancet 373 (9659): 226–33. doi:10.1016/S0140-6736(09)60071-4. PMID 19150703.