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Neonatal Pathophysiology > Bacterial Infections > Flashcards

Bacterial Infections Flashcards

1
Q

What is the definition of colonization?

A

presence of bacteria on a body surface (ex: skin, mouth, intestines, airways, etc), but the presence of bacteria does not cause disease in a person

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2
Q

What is the definition of infection/sepsis?

A

result of bacteria causing an illness, the s/s of infx depend on where the infx is

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3
Q

What is the definition of septicemia?

A

a serious, life threatening problem caused by a bacterial organism in the blood

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4
Q

What is the incidence of bacterial infections in the newborn?

A

1-8:1000 live births

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5
Q

What is the mortality rate for neonatal bacterial infx?

A

as high as 40% for preterm infant (early onset)

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6
Q

The significant mortality of neonatal sepsis necessitates what action by the provider?

A

early detection and treatment of sepsis to optimize the prognosis

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7
Q

What are common risk factors for neonatal bacterial infx?

A

PPROM, PROM >18h, PTL, chorioamnionitis, recent maternal infx, maternal fever in the perinatal period, maternal GU tract infx (including UTI and STD), perinatal asphyxia and invasive procedures

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8
Q

What is chorioamnionitis?

A

dx made by constellation of clinical symptoms including: maternal temp >100.4, maternal HR >100bpm, fetal HR >160bpm, uterine fundal tenderness, foul smelling amniotic or vaginal discharge, purulent appearing amniotic fluid

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9
Q

How does perinatal asphyxia increase an infant’s risk for bacterial infx?

A

increased especially with PROM >18h, during asphyxial event, baby may gasp and deeply inhale infected amniotic fluid

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10
Q

What invasive procedures increase an infant’s risk for bacterial infx?

A

procedures prior to del that interfere with the integrity of the amniotic cavity- CVS, amnio; or during delivery- fetal scalp electrode, vacuum assistance; or after delivery- PIV insertion, central lines, intubation

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11
Q

What is Gram staining?

A

the first step in identifying an organism, allows for differentiations of bacteria into 1 of 2 categories; G+ appear purple/blue (retain the stain) and G- appear pink

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12
Q

What are some common seen Gram positive bacterial organisms in the NICU population?

A

coagulase-negative staphylococcus, staphylocccus aureus, listeria monocytogenes, streptococcus pneumoniae and group A streptococcus

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13
Q

What are some common seen Gram negative bacterial organisms in the NICU population?

A

neisseria meningitdies, haemophilus influenza, klebsiella pneumoniae, pseudomonoas aeruginosa, acinetobacter species, citrobacter species, enterobacter species, serratia marcescens and proteus species

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14
Q

What is early onset sepsis?

A

within the first 72 h of life; can begin in utero as resul of swallowing or inhaling infected amniotic fluid; usually present within the first 24-48h

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15
Q

What is late onset sepsis?

A

after the first 72h of life

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16
Q

What are commonly presenting signs of bacterial infx in neonates?

A

respiratory distress, temperature instability, feeding intolerance, cardiovascular signs, abnormal neurologic status and abnormal skin findings * many of these signs may also be present with other concurrent illnesses

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17
Q

What clinical presentation of the respiratory system would indicate bacterial infx?

A

tachypnes, G/F/R, apeana, cyanosis, development/increased supplemental O2 requirement, respiratory support

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18
Q

What clinical presentation of temperature would indicate bacterial infx?

A

more commonly hypothermia, could be hyperthermia; temperature lability

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19
Q

What clinical presentation of feeding intolerance would indicate bacterial infx?

A

increased gastric residuals, poor feeding patterns, vomiting

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20
Q

What clinical presentation of the cardiovascular system would indicate bacterial infx?

A

tachycardia, bradycardia, mottling, hypotension, pale or grey skin color

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21
Q

What clinical presentation of the neuro system would indicate bacterial infx?

A

irritable, lethargy, sleepiness, sz and hypotonia

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22
Q

What clinical presentation of the integumentary system would indicate bacterial infx?

A

omphalitis, blisters on the skin, swelling or redness of the soft tissue, cellulitis, necrotic skin lesions

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23
Q

What is a WBC?

A

fx to protect the body from infx; produced in the bone marrow along with RBCs and platelets

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24
Q

What are the 5 different types of WBCs?

A

Neutrophils, eosinophils, basophils, lymphocytes and monocytes

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25
Q

What are neutrophils primarily responsible for?

A

killing and digesting bacteria

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26
Q

What are mature neutrophils called?

A

segmented neutrophils- segs (has a segmented nucleus), polymorphonuclear (PMNs), neuts, polys

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27
Q

What are immature neutrophils called?

A

bands, juveniles and stabs

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28
Q

How does a neutrophil mature?

A

in the bone marrow from a myeloblast into a segmented neutrophil

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29
Q

What comprises the neutrophil storage pool?

A

in the bone marrow the metamylocytes, bands and segmented neutrophils

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30
Q

How does the neutrophil storage pool of a neonate differ from an adult?

A

significantly smaller per kg of body weight

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31
Q

Under normal circumstances (no active infx), how do neutrophils fx?

A

mature neutrophils are released from the storage pool into the blood stream, where they circulate for 6-8h, then migrate in the tissue where they live for ~ 24h.

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32
Q

How do neutrophils fx in the context of an active infx?

A

immature neutrophils-bands, are also released from the bone marrow to the blood stream as the body attempts to maximize the # of circulating neutrophils

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33
Q

What is meant by a “left shift”?

A

appearance of immature neutrophils in the blood

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34
Q

What is neutrophil chemotaxis?

A

when released, neutrophils will then migrate to the site of infx in response to bacterial toxins. this movement toward the site is immature, especially in a preterm infant

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35
Q

How is a CBC with diff and plt count helpful in evaluating the presence of a bacterial infx?

A

first line SCREENING tool to detect sepsis; the peripheral CBC is accurate, simple and sensitive as a method of screening for potential infx. a babe with sepsis may have a normal CBC & CRP in early phase of illness

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36
Q

With the onset of bacterial infection, when can the first change in a CBC & CRP be detected?

A

the onset of time bw the first ∆ in CBC and the onset of infx may be 4-6h; the onset of time bw the first ∆ in CRP and the onset of infx may be 8-12h

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37
Q

How should an infant be cared for in the latent period of a bacterial infx?

A

during the latent period, the neonate is infected and needs abx but has a normal CBC & CRP. never withhold abx on the basis of a normal C&C

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38
Q

What is a blood culture?

A

an adequate amount of blood is plead in the culture bottle to detect the presence of bacteria in the blood

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39
Q

What can factors can potentially alter the results of a BCX?

A

without adequate blood volume there is a risk of a false negative cx, if MOB had abx prior to del- cx may not grow out bc of maternal and therefore, fetal treatment

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40
Q

How is a glucose level helpful in evaluating the presence of a bacterial infx?

A

hypoglycemia can p/w sepsis

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41
Q

How is a CRP helpful in evaluating the presence of a bacterial infx?

A

CRP is a protein produced by the liver during states of inflammation, infx, trauma or tissue necrosis; an acute phase reactant

42
Q

When are CRP levels generally elevated?

A

bacterial infx, meningitis, respiratory illness, s/p surgery, bruising, immunizations, VD>CSX, even after vacuum or forceps delivery; generally elevates 4-8h post inflammatory response events; remains elevated during ongoing inflammation, declines when inciting event resolves

43
Q

How should a CRP be interpreted?

A

CRP does not cross the placenta, so results are not MOB’s. normal value is <1; not always elevated, so decision to tx should not be made solely on CRP; non specific and multifactorial; trends are more important than single values

44
Q

What laboratory evaluations should be considered when ruling out a bacterial infx?

A

CBC, BCX, glucose, CRP, blood gas, CSF, electrolytes, iCalcium, renal fx test, liver fx test and magnesium levels

45
Q

How are electrolytes helpful in evaluating the presence of a bacterial infx?

A

evaluating Na & K levels, metabolic acidosis; magnesium- especially if MOB got mag in delivery

46
Q

How is a bacterial infx directly diagnosed?

A

through the cx of a normally sterile fluid (ex: CSF, blood, urine)

47
Q

How is a bacterial infx indirectly diagnosed?

A

CBC, acute phase reactants (CRP, ESR)

48
Q

How is a CBC evaluated?

A

number of WBCs, ANC, immature to total ratio and plt count

49
Q

At what level is a patient considered neutropenic?

A

ANC <1350

50
Q

Why is neutropenia significant?

A

strong indicator of infx

51
Q

Why is an ANC significant?

A

tells you the total number of neutrophils available to fight infx

52
Q

Why is the immature to total ratio (I:T) significant?

A

tells you what percentage of the circulating neutrophils are immature

53
Q

What is the normal range of RBCs?

A

5.1-5.8

54
Q

What is the normal range of WBCs?

A

5-30

55
Q

What is the normal range of HCT?

A

52-58%

56
Q

What is the normal range of platelets?

A

150-400

57
Q

What is the normal range of bands?

A

9% (not abnormal to have some bands)

58
Q

What is the normal range of segs?

A

52%

59
Q

What is the normal range of lymphocytes?

A

31%

60
Q

What is the normal range of monocytes?

A

5.8%

61
Q

How does maternal hypertension affect a neonate’s ANC?

A

MOB with HTN may have a decreased ANC compared to MOB without HTN

62
Q

How is ANC calculated?

A

ANC= (% segs + % immature [bands, metas, myelos]) x WBC

63
Q

What is the normal course of the WBC and neutrophi count post delivery?

A

rise in the first day of life, in term infants ANC peaks about 8h post del- therefore a declining neutrophil count (rather than the expected physiologic increase) is concerning for infx

64
Q

What might a low ANC indicate?

A

depletion of neutrophil storage pool or that the infant is not going to be able to mobilize enough neutrophils necessary to fight a bacterial infx

65
Q

Why is exhaustion of the neutrophil storage pool of utmost concern?

A

infants who deplete their stores while fighting an infx are at the highest risk of dying from sepsis

66
Q

Why is the I:T ratio significant for infants with bacterial sepsis?

A

this calculation tells us what proportion of the circulating neutrophils are immature

67
Q

How do you calculate I:T ratio?

A

(all immature WBCs- bands, metas, myelos)/total number of WBCs

68
Q

What does a I:T ration of >0.2 suggestive of?

A

sepsis

69
Q

What does a I:T ration of >0.8 suggestive of?

A

bone marrow depletion and correlated with higher risk of death from sepsis

70
Q

What factors can potential cause the clinician to misinterpret lab values as a “left shift”?

A

violent crying, stressful delivery, PIH or the lab not correcting for nucleated RBCs

71
Q

What can induce thrombocytopenia?

A

bacterial, fungal and viral infx

72
Q

How should a platelet count of <100k be interpreted?

A

abnormal, needs evaluation, examine for s/s of bleeding

73
Q

How should a platelet count of <50k be interpreted?

A

risk of bleeding is increased, examine for s/s of bleeding

74
Q

How should a platelet count of <20k be interpreted?

A

dangerously low, examine for s/s of bleeding, consider a plt transfusion; at risk for intracranial bleeding

75
Q

How should abx therapy be tailored to treat early onset sepsis?

A

need coverage for G+ and G- organisms, abx asap

76
Q

What kind of coverage does ampicllin provide?

A

G+ (liseria and GBS)

77
Q

What kind of coverage does genatmicin provide?

A

G-; amino glycosides require therapeutic level monitoring

78
Q

What abx should be considered if nephrotoxicity is a concern?

A

cefotaxime (claforan) instead of gent

79
Q

How should abx therapy be tailored to treat late onset sepsis?

A

need coverage for staphylococci and G- bacilli (pseudomonas); typically gent and vanc

80
Q

What is the length of time required for abx therapy for the treatment of sepsis?

A

depending on individuals clinical presentation, risk factors and medical history- may need a 7-14d course depending on the baby and babes response

81
Q

What is the length of time required for abx therapy for the treatment of pneumonia with a negative blood cx?

A

5-10d

82
Q

What is the length of time required for abx therapy for the treatment of a significant left shift with negative BCX?

A

5-7d

83
Q

What is meningitis?

A

an inflammation of the membrane that lines the brain and the spinal column; one of the most serious dz affecting babes; etiology can be bacterial or viral

84
Q

What is the incidence of meningitis?

A

0.4-1 per 1000 live birth

85
Q

What are common risk factors for meningitis?

A

premature infants, male, infants with CNS defects and infants of mothers with obstetric complications

86
Q

What are the most common pathogens for meningitis?

A

also the most common for bacteremia: GBS and E.Coli

87
Q

How does meningitis commonly present?

A

begins with subtle signs of sepsis; additional specific signs include: tense or bulging fontanels, high-pitched cry, sz and neck retraction

88
Q

What is the diagnostic study for meningitis?

A

culture of the CSF

89
Q

What are non-diagnostic studies that might also be helpful in the evaluation of meningitis in the neonate?

A

CSF glucose, CSF protein and CSF cell count

90
Q

What can the CSF glucose indicate in the evaluation of meningitis in the neonate?

A

glucose typically falls with meningitis, must be compared to serum glucose at the time of the LP

91
Q

What can the CSF protein indicate in the evaluation of meningitis in the neonate?

A

typically increases with meningitis; if a bloody tap, the sample might skew higher with more protein

92
Q

What can the CSF cell counts indicate in the evaluation of meningitis in the neonate?

A

typically increased WBC with meningitis

93
Q

When meningitis is suspected, how should abx therapy be delivered?

A

tx should be initiated immediately; amp (G+ coverage), gent (G- coverage) and cefotax (G- coverage)

94
Q

What is the length of time required for abx therapy for the treatment of G+ meningitis?

A

~ 2 weeks

95
Q

What is the length of time required for abx therapy for the treatment of G- meningitis?

A

~ 3 weeks

96
Q

When should a repeat CSF cx be collected?

A

2-3d after initiation of treatment to ensure effective coverage

97
Q

What is the mortality rate a/w meningitis?

A

poor prognosis; mortality rates as high as 30-60%

98
Q

What are potential outcomes for infants that survive meningitis?

A

50% may have serious neuro sequelae (hearing loss, communicating/non-communicating hydrocephalus, abnormal speech, mental or motor loss of varying degrees and sz activity) 20-50% of surviving infants will experience at least 1 or more

99
Q

When is HSV vertical transmission more likely to occur?

A

severe neonatal infx and is much more likely to occur if the MOB contracts a primary episode of HSV late in gestation

100
Q

What are s/s of HSV infx?

A

skin vesicles, poor feeding, lethargy, fever, shock, sz (if CNS involvement)

101
Q

Why is a PCR now the recommendation for HSV encephalitis diagnosis?

A

more accurate than a CSF cx, PCR can make many copies of viral DNA so even small amounts can be detected; $$$, not approved for genital testing; results can be returned quicker

Neonatal Pathophysiology (17 decks)

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