Fever and Bacteremia

1
Fever and Bacteremia

• Alyssa Rake, M.D.
• Baystate Medical Center
• Department of Pediatrics
• 2004-2005

2
Objectives

• Definition and pathogenesis of fever
• Contrast fever, bacteremia, sepsis, and septic
  shock
• Be familiar with the Rochester criteria
• Learn more about the history and physical exam in
  infants
• Understand differences in the workup and
  management of fever in various age groups

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Case 1

• G.K. is a FT 18 day old male infant. Mom brings
  him to the office because he is taking much less
  po then usual. On exam you find him alert and
  crying but consolable, T 101.4, P 120, R 45, bp
  80/40.
• What other questions do you ask?
• What are you worried about?
• How do you manage him?

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Whats the big fuss?

• Infants have immature immune systems passive
  immunity waning and active not fully mature
• Increased risk of bacterial infections due to
  perinatal factors
• Difficult to assess clinically
• No immunizations until 2 months

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How do you take a temperature?

• Rectal thermometer is the most accurate and
  reliable
• Oral temp acceptable for older children
• Axillary temp also acceptable for older
  individuals who are not moving around
• Ear temp inaccurate

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Definition of fever

• Rectal temp gt100.4 F (38 C)
• Oral temp gt101.3 F (38.5 C)
• Axillary temp gt101.3 F (38.5 C)
• Can vary with outside temp, clothing layers,
  parental temp, etc.
• Hyperpyrexia temp gt106 F (41 C)

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Physiology of fever

• Body temp. is regulated by neurons in preoptic
  and anterior hypothalamus
• Pyrogens reach the hypothalamus via the
  bloodstream and release arachadonic acid
• Arachadonic acid is metabolized into PGE2
• PGE2 resets the hypothalamic thermostat
• Antipyretics reduce the production of PGE2

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Thermoregulatory responses

• Purpose to maintain normal body temperature
• Dilation/constriction of capillary beds
• Sweating
• Extracellular fluid regulation
• Behavioral responses

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Benefits of fever

• Helps the body fight infection
• Turns on the bodys immune system
• May shorten an illness
• Does not cause symptoms until 102-103 F
  (38.9-39.5 C)
• Not harmful until gt107 F (41.7 C)

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Effects of fever

• Increase O2 consumption
• Increase CO2 production
• Increase cardiac output
• Worsen metabolic instability
• Lower seizure threshold
• Exacerbate heart lung instability

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Categories of febrile illness

• Usually acute (lt 1 week) and has localizing
  symptoms
• Fever without a source seen more often in ages
  0-3 yrs.
• Fever of unknown origin- fever gt14 days without a
  localizing source

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Definition of bacteremia and sepsis

• Bacteremia Positive blood cultures indicating
  the presence of bacteria in the bloodstream
• Sepsis Systemic response to infection
  (tachycardia, tachypnea, hyper/hypothermia,
  neutropenia, and/or leukocytosis)
• Sepsis syndrome SIRS, Sepsis with end organ
  effects (e.g. hypoxemia, lactic acidosis,
  oliguria)
• Septic shock Sepsis syndrome hypotension

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Causes of sepsis

• Preterm infants GBS, Coagulase negative staph,
  Candida sp.
• Neonates GBS, Listeria, Gram negative
  enterococcus
• Ages 3-36 months H. flu, S. pneumo, S. aureus,
  group A strep, N. meningitidis

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Other high risk group considerations

• Sickle cell patients S. pneumo, Salmonella, and
  Staph sp.
• Asplenic patients Encapsulated organisms (N.
  meningitidis, S. pneumo, and H. flu)

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Clinical evaluation of a febrile infant- History

• PMHx- Prematurity, prior admissions/surgeries,
  comorbid illness
• Immunization Hx
• Amount po intake
• wet diapers
• Fussy, sleeping more, consolable, lethargic
• Sick contacts
• Constitutional sx- rhinorrhea, cough, emesis,
  diarrhea

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Clinical evaluation of a febrile infant- Physical
Exam

• Vital signs!!
• How does the infant appear?
• Color
• Level of alertness
• Response to stimuli
• Eye contact
• Suck
• Irritability/ Consolability
• Source identifiable in gt70 infants if you do a
  thorough HP

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Signs of sepsis in infants

• Poor feeding
• Irritability
• Lethargy
• Oliguria
• Cyanosis
• Apnea
• Tachypnea/ hyperventillation

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Rochester Criteria

• Baraff, LJ et al. Practice Guidelines for
  Management of Infants and Children 1-36 Months of
  Age With Fever Without Source. Pediatrics. July
  1993 821.
• Used to assess febrile infants without an
  identifiable source
• To define clinical and laboratory characteristics
  of a low risk infant
• If establish low risk may treat as an outpatient
  /- antibiotics

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Risk of infection in toxic-appearing febrile
infants lt 12 weeks old

• Probability of serious bacterial infection 17
• Probability of bacteremia 11
• Probability of bacterial meningitis 4
• Risk continues to decrease with HIB and now
  Prevnar vaccines

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Risk of infection in non-toxic-appearing febrile
infants lt 12 weeks old

• Probability of SBI 8.6
• Probability of bacteremia 2
• Probability of bacterial meningitis 1

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Risk of infection in low risk febrile infants lt
12 weeks old

• Probability SBI 1.4
• Probability bacteremia 1.1
• Probability bacterial meningitis 0.5
• Negative predictive value of low risk criteria
  99.3

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Low risk laboratory markers

• WBC count lt15,000 and gt5,000/mm3
• Absolute band count lt1500/mm3
• Catheterized/suprapubic UA lt10 WBC per HPF
• UA negative leukocyte esterase
• Diarrhea lt5 WBC per HPF on stool smear

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Management of Infants age 0-28 days

• All get sepsis workup including CBC with diff,
  UA, blood, urine, and CSF cultures
• All are admitted to the hospital for 48 hrs.
• Apnea monitors
• Bugs to cover GBS, Listeria, gram negative
  enterococcus
• Empiric treatment with IV/IM Ampicillin and
  Gentamicin

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Management of Infants age 28-90 days

• Full HP
• Basic lab work CBC and UA
• Establish high vs. low risk
• If ill-appearing or high risk admit and full
  sepsis evaluation
• Treatment with IV/IM Ceftriaxone
• If low risk may
• -Admit and observe
• -Monitor as an outpatient

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Management of Children ages 3-36 mos.

• Toxic appearing Admit, full sepsis workup
• Non-toxic temp lt39 C symptomatic tx.
• Non-toxic temp gt39 C CBC, UA
• /- blood, urine cx
• /- empiric tx with Ceftriaxone

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Treatment of fever

• Unwrap baby
• Cool baths/ sponge off
• Ibuprofen 5-10 mg/kg Q6-8 hours
• Acetaminophen 10-15 mg/kg Q4-6 hours
• Avoid Aspirin!!

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Complications of bacteremia

• 30-40 resolve with treatment, esp.
• S. pnemuo
• Meningitis
• Pneumonia
• Cellulitis
• Septic arthritis
• Endocarditis

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Case 2

• D.H. is a 2 month old female who presents to you
  office with a temp 101.2. She is alert and
  active with a normal exam.
• How do you manage this patient?

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Case 3

• T.O. is a 2 month male who presents to your
  office with a temp 101.2. Mom reports that he
  has refused his bottle all day and has been
  sleeping more then usual. On exam he is asleep
  and arouses for a few seconds at a time. His
  extremities are cool and mottled without any
  rash.
• How do you manage this patient?

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Case 4

• AJ is an 18 month old female who presents to the
  ED with temp. to 104.5. She is more cranky then
  usual but taking good po at home and playing with
  her sibs. Her exam is unremarkable.
• How do you manage this patient?

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Case 4 Cont.

• The next day she develops an erythematous rash on
  her trunk and extremities.
• Now what do you do?
• Differential diagnosis?

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Fever and petechiae

• This is a pediatric emergency!!
• High risk of bacteremia, sepsis, and meningitis
• Meningococcus most often, but H. flu type B can
  also be a culprit
• Management includes admission, blood and CSF cx,
  and IV/IM Ceftriaxone
• Do not wait for workup to give CTX

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Are we doing the right thing?

• How useful are the tests?
• Viral infections more common
• Many infections with high wbc not SBI, will clear
  themselves
• Contaminants in blood cultures
• Effectiveness of antibiotics?
• PO vs IV
• Waiting 24-48 hours for cultures
• Hospitalization difficult on kids/families

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Are we doing the right thing?Pantell RH, Newman
TB, et al. Management and Outcomes of Care of
Fever in Early Infancy. JAMA. 2004 291
1203-1212.

• PROS clinicians- 573 Pediatricians across US and
  PR
• 3066 Infants lt3 months with fever gt38 C enrolled
• Only followed guidelines 42
• Hospitalized 36, labs 75, treated 57
• Bacteremia 1.8, meningitis 0.5
• Well appearing 0.4 SBI
• Treated 61/63 meningitis cases
• Observed Practitioner management same accuracy as
  published guidelines

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References

• Behrman et al. Nelson Textbook of Pediatrics,
  16th Edition. Chapters 171-173.
• Clinical Practice Guidelines-Baystate Medical
  Center Management of Febrile Infants lt3 months.
  1999
• Baraff LJ, Bass JW, et al. Pediatric Guideline
  for the Management of Infants and Children 0 to
  36 Months of Age With Fever Without Source.
  Pediatrics. July 1992 921.
• Management of the Young Febrile Child A
  Commentary on Recent Practice Guidelines.
  Pediatrics. 1997 100128-138.
• Pantell RH, Newman TB, et al. Management and
  Outcomes of Care of Fever in Early Infancy. JAMA.
  2004 291 1203-1212.