EXAM 3 Pediatric Infections Flashcards
describe sepsis
- severe infection
- systemic inflammatory response
- multiple organ dysfunction
- vasodilation
- leukocyte accumulation
- increased microvascular permeability
what is the relationship between infection, SIRS, sepsis, severe sepsis, and septic shock?
what is the definition of SIRS in kids?
- core temp >38.5 or <36*C
- tachycardia (>2 SD above normal for age) or bradycardia (<10th percentile for age)
- mean respiratory rate >2 SD above normal for age
- high or low WBC, or >10% immature neutrophils
- *you do not measure BP in children to diagnose SIRS*
which f the following makes neonates more susceptible to infections?
A) less IgG production
B) declining maternal IgG
C) less cytokine production
D) decreased function of neutrophils
all of these
in infants, there is a lot of change in their immune system during the first ___ months of life
3
T and B cells are present in utero, but they have to co-exist with ___
manternal immune system
the number of T lymphocytes are similar/increased in infants, but the ___ is different
function
describe how the function of lymphocytes in infants is different than in adults
- anti-inflammatory cytokine production (T cells) diminished
- immunoglobulin synthesis (B cells) is less
- neutrophils differ from adult functional capacity
what is an important consideration regarding pediatric HIV infection in infants?
CD4 T cell counts will have different meanings in children than in adults, so they will actually use percentages instead of numbers
during the first ___ months of life, there is an increased risk of serious ___ infection
- 0-3
- bacterial
what is considered a neonatal fever?
- rectal temp >/= 38
- may be only sign of infection
what is an SBI?
- serious bacterial infection
- meningitis, bacteremia, UTI
- pneumonia, osteomyelitis/septic arthritis, SSTI, bacterial gastroenteritis
globally, neonatal SBIs are responsible for what fraction of neonatal deaths?
1/3-1/4
___% of infants (<90 days old) with fever have an SBI
8.5%
what accounts for most of the SBIs in infants <90 days old? what percent of infants are affected?
- UTIs
- 73% of infants with SBI
describe the incidence of bacteremia and meningitis in infants
decreases with age
- 0-30 days = 3% with bacteremia, 1.1% with meningitis
- 1-2 months = 1.4% with bacteremia, 0.4% with meningitis
- 2-3 months = 0.7% with bacteremia, 0% with meningitis
what are the most common causes of neonatal SBI?
A) GBS, salmonella sp., e. coli
B) GBS, staph aureus, e.coli
C) GBS, listeria, e. coli
D) staph aureus, e. coli, listeria
E) GBS, listeria, strep pneumoniae
C) GBS, listeria, e. coli
what are the most common bacterial pathogens of neonatal SBI?
- group B strep (s. agalactiae)
- e. coli (and other gram neg enteric bugs)
- listeria monocytogenes
what are the major viral causes of neonatal sepsis?
- HSV 1 and 2
- VZN
- enteroviruses
- influenza
- adenoviruses
- RSV
describe group B strep
- gram positive cocci
- beta-hemolytic
- lancefield group B
- important virulence factor
what is the GBS colonization rate of pregnant women?
- 15-40%
- constant and/or intermittent
- with improved cx techniques → 30-50% colonization
- test pregnant women at >/= 35 weeks gestation
describe neonatal acquisition of GBS
- in utero by ascending route or at time of delivery
- 50% transmission rate prior to prophylaxis
- after birth: mucous membranes
___ are common colonizers of GI and GU tracts; less commonly the pharynx
GBS
what are the clinical manifestations of GBS infection?
- early-onset (<7 days; median age at onset 1 hour)
- late-onset (7-89 days)
- late, late-onset (90+ days)
early onset GBS infection is commonly associated with ___
maternal OB complications
___ onset GBS disease has the highest mortality rate at ___%
- early
- 5-10%
what are the symptoms of early onset GBS disease
- respiratory distress, poor feeding, lethargy, apnes/bradycardia
- septicemia (35-50%)
- meningitis (5-10%)
- respiratory distress (35-40%)
what are the factors that predict early onset GBS disease mortality?
- birthweight <2500g
- ANC <1500 cells/mm3
- hypotension
- apnea
- initial pH <7.25
- pleural effusion on initial chest Xray
___ is the #1 cause of early neonatal morbidity and mortality in the US
GBS
describe IAP
- intrapartum antimicrobial prophylaxis
- initiated in 1996
- decreased early onset GBS disease by 70%
IAP only reduces ___ onset GBS disease
early
what is the drug of choice for GBS?
penicillin or ampicillin
only use clindamycin if you know the isolate is susceptible
describe listeria monocytogenes
- gram pos rod
- facultatively anaerobic, nonsporulating
- incomplete beta-hemolysis
- polar flagellae - tumbling motility at 25*C
- grows well at refrigerator temps (4-10*C)
what bacteria can be tricky to identify clinically, and can appear like diphtheroids, cocci, diplococci?
listeria monocytogenes
T or F
you should never narrow your antibiotics based on a gram stain
true
what bacteria is described by the following:
imporant zoonoses (especially in herd animals)
widespread in nature - soil, decaying vegetation, fecal flora of mammals
isolated from stool of healthy adults (5%)
lots of foods are contaminated
food-related outbreaks - milk, soft cheeses, ready to eat pork, deli meat, hot dogs, cantelopes
listeria monocytogenes
describe the pathogenesis of listeria monocytogenes in neonates
- in utero infection - stillbirth/abortion
- granulomatosis infantiseptica
- early onset sepsis
- acquired in utero
- associated with prematurity
- late onset meningitis
- onset 2 weeks of age
- acquired vis birth canal
what is the drug of choice for treating infections caused by listeria monocytogenes?
- ampicillin, plus gentamicin for synergy in certain cases
- *cephalosporins don’t have activity
describe e. coli
- gram neg, motile red
- facultatively anaerobic
- lactose-fermenting (most)
- very versatile, many niches
- 171 somatic (O) antigens and 56 flagellar (H) antigens
describe the epidemiology of e. coli
- predominant facultative anaerobic flora of the human GI tract
- key for intestinal homeostasis
- also found in maternal genital tract
what are the 3 types of e. coli?
- uropathogenic e. coli
- diarrheagenic e. coli
- e. coli causing disseminated infection
what is the treatment for infection from e. coli?
- textbooks say ampicillin, but beware of resistance - extended spectrum cephalosporin, such as cefotaxime, better choice
- at PCH, about 50% of our e. coli are ampicillin resistant
- pearl:
- think galactosemia with e. coli sepsis
describe history when evaluating a febrile infant
- fever and hypothermia
- poor feeding
- lethargic
- inconsolable
- grunting/respiratory distress
- poor color
- decreased urine output
- apnea
- jaundice
describe physical exam when evaluating a febrile infant
- temp (>38 or <36*C)
- HR, RR, O2 saturation, BP
- general: do they look sick?
- HEENT: anterior fontanelle, sclera icteric?, mucous membranes for hydration
- CV/resp: HR, work of breathing (retractions, nasal flaring)
- abdomen: hepato/splenomegaly?, distended?, bowel loops?
- skin: color, perfusion, petechiae, rashes
- neuro: what reflexes are normal? tone?
describe lab evaluation when evaluating a febrile infant
- CBC with differential
- blood gas
- coagulation tests
- comprehensive metabolic panel
- CRP
- urinalysis
- blood and urine cultures
- CSF for gram stain and culture, cell count, glucose, protein
what types of imaging should be considered when evaluating a febrile infant?
- CXR
- KUB
- brain imaging
- others
describe CBC in buildling a lab case for sepsis
- low or high WBC, left shift of WBC (predominance of band forms, PMNs)
- thrombocytopenia (sign of DIC)
- prolonged PT/INR/PTT, low fibrinogen
describe CMP in buildling a lab case for sepsis
- hepatitis
- acute renal insufficiency (elevated BUN, Cr)
- low HCO3 (sign of acute acidosis)
in addition to CBC and CMP, describe other components of buildling a lab case for sepsis
- inflammatory markers elevated - CRP, ESR, procalcitonin
- blood gas - acidosis (low pH), lower pCO2, base deficit, elevated lactate
- urine - signs of infection (WBCs, nitrites, leukocyte esterase), signs of kidney injury (protein, casts, high specific gravity)
- CSF - high WBC (with left shift), high protein, low glucose
what is the best choice for empiric antimicrobial therapy for a febrile neonate?
A) ampicillin and gentamycin
B) ampicillin, cefotaxime, and gentamicin
C) vancomycin, cefotaxime, and gentamicin
D) ceftriaxone and gentamicin
E) vancomycin and ampicillin
B) ampicillin, cefotaxime, and gentamicin
what are the empiric treatment options for febrile infants?
- ampicillin, gentamicin, cefotaxime, acyclovir (HSV)
- special circumstances - vancomycin, nafcillin
what is the target of ampicillin?
- gram positive infections (GBS and listeria)
- only active agent for listeria; drug of choice for GBS
what is the target for gentamicin?
- synergy for listeria and GBS
- additional gram neg coverage
what is the target for cefotaxime?
- ceftriaxone if >1 month old
- gram neg coverage (e. coli, etc.)
- especially important if suspecting meningitis (good CSF penetration)
describe neonatal conjuctivitis
- # 1 cause of neonatal conjuctivitis = chemical irritation from silver nitrate
- ophthalmia neonatorum = conjuctivitis in 1st 4 weeks of life
- chlamydia trachomatis (2-40%)
- neisseria gonorrhoeae (<1%)
- other bacteria (30-50%)
- HSV (<1%)
what is the possible prevention of neonatal conjuctivitis?
erythromycin
describe chlamydia trachomatis
- obligate intracellular bacterium
- # 1 reportable STD in the US
- test of cure imporant in pregnant women
- 50% of infants born to infected mothers
- conjuctavitis (25-50%), pneumonia (5-20%)
- incubation period for neonates - 5-14 days
- pneumonia - 3 weeks to 3 months
describe the diagnosis for chlamydia trachomatis
eye swab for NAAT and culture; talk to lab
describe treatment for chlamydia trachomatis
erythromycin PO for 14 days or azithromycin PO for 5 days
also treat the mother
chlamydia trachomatis is not prevented by ___ erythromycin
ocular
describe the prevention of perinatal/neonatal infections
- group B strep
- ophthalmia neonatorum (gonorrhea)
- hepatitis B
- HIV
- HSV
- vaccinations of mother
- influenza
- rubella
- pertussis
- VZV
what are important group B strep virulence factors?
- pilus-like structures
- alpha C surface protein
- beta-hemolysis/cytolysin
- capsular polysaccharides
describe universal screening for GBS disease
- all pregnant women
- 35-37 weeks gestation
- vaginal-rectal specimen
- inform lab when submitting a urine sample from a pregnant woman
- antimicrobial susceptibility (if using an antibiotic other than PCN or AMP)
describe treatment for GBS disease
- drug of choice = penicillin G 5 million U IV, then 2.5-3 millions U IV q4 hours before birth
- acceptable alternative = ampicillin
- PCN-allergic (not anaphylaxis or hives) = cefazolin
- clindamycin (must have susc. testing) or vancomycin
why are bacterial infections in babies in the first 3 months of life taken so seriously?
because of the nature of babies’ immune systems, they cannot localize and take care of bacterial infections the same way that adults can
