Group B Streptococcus

1
Group B Streptococcus

• Adunni Morohunfola, M.D.
• Dept. of Pediatrics, Texas Tech

2
Etiolgy

• Group B streptococcus(Strep.agalactiae)
• Facultative encapsulated gram-positive
  diplococcus
• Produces a narrow zone of beta hemolysis on
  blood agar.
• Most strains are resistant to bacitracin and
  septrin
• Positive CAMP

3
Etiology

• Divided into the following serotypes based on
  capsular polysacch. types Ia, Ib,II and III
  through VII.
• All serotypes can cause infections in newborns
  but Ia,II,III,V account for 90.
• Late onset dx and early-onset meningitis is due
  to type III.

4
Epidemiology

• Approx. 10-35 of pregnant women are
  asymptomatic carriers of GBS in the genital and
  G. Intestinal tract.
• At birth 1 in 2 infants born to colonized mothers
  are colonized.
• 98 of colonized infants are without symptoms,
  but 1-2 developed GBS.
• Nearly 50 of sexual partners of colonized women
  are colonized themselves.

5
Epidemiology

• Incidence rate of 0.2 3.7/1000 live births.
• Mortality rate of 5-15/1000 live births.
• More recent surveillance shows a decrease in I.R
  to 0.8 per 1000 live births-reflection of use of
  maternal antibiotic prophylaxis.
• Incidence rate at Thomason
  - 0.57
  /1000 live births in 2000
  - 0.40/1000 live births in 2001.

6
Incidence per 1000 live births of early-onset GBS
disease at Thomason Hospital

• Data Source Dept. of Pediatrics, Texas Tech
  
  
  
  
  
  
• 
  

7
Epidemiology

• Direct cost of treating neonate with proven GBS
  300 million dollars/year.
• Indirect costs
• Mothers prophylaxis?
• Babys treatment for suspected sepsis?

8
Transmission/ Incubation period.

• Vertical transmission From mother to infant
  occurs shortly before or during delivery.
• After delivery, person-to-person transmission
  can occur via hand contamination.
• Incubation Period
• early onset disease is less than 6 days
• late onset disease is unknown.

9
Risk factors for Colonization

• Infants born lt 37weeks
• Heavily colonized mothers
• PROM gt 18 hrs.
• Intrapartum fever 100.4 F
• Maternal chorioamnionitis
• GBS bacteruria
• Maternal age lt 20yrs
• African American ethnicity

10
Early onset vs. Late onset

• Occurs in 1st week. Usually before 72hrs
• Pathophysiology.
  -Colonization.
  
  
  
  
  
• -Immature host defense mech particularly among
  low birth wt infants.

• 1week to 6months. Usually at 3-4 weeks.
• Pathopysiology. -Related to
  initial colonization. -Alteration of the mucosa
  barrier by a viral resp tract inf.,weakened host
  defense,decrease amt of maternal antibodies.
  

11
Early Onset Vs Late Onset

• Transmission
  
  -aquired thru vertical transmission.
• 
  -ascending infection, duration of rupture of
  memb. directly proportional to I.R.
• 
  
  -during passage thru a colonized birth
  canal.

• Transmission -aquired
  thru horizontal transmission
  -nurseries -hospital
  personnel -community

12
Early Onset Vs Late onset

• Clinical Manifestation
  
  -Pneumoniarespiratory distress, tachypnea
  cyanosis,hypoxaemia apnea
  -Pulmonary HTN
  -Shock -Poor feeding
  -Abnormal temperature
  -Less often meningitis

• Clinical manifestation
• Occult bacteremia, meningitis, ventriculitis, and
  other focal infections, e.g. septic arthritis,
  osteomyelitis.

13
Laboratory Findings

• Identification of Gm ve cocci in pairs and in
  chains in fluids that are sterile indicate
  invasive disease.
  
  -CSF,Blood,Pleural
  Fluid,Joint Fluid.
• Gm ve cocci in gastric or tracheal aspirate,skin
  and mucous memb indicate colonization.
• Rapid antigen test in CSF.
  -rapid test that identify GBS
  antigen In other body fluids not recommended.
  

14
LABORATORY fINDINGS

• Non specific tests
  -CBC Leukocytosis, Lt
  shift, increased band count, Increase I.T ratio
  gt0.20,neutropenia, thrombocytopenia
  . -Incr.
  CRP.
  -Cxray showing
  pneumonia, atelectasis.

15
Differential Diagnosis

• Sepsis
• Aspiration pneumonia(meconium)
• HMD
• Wet lung(TTNB)
• Total anomalous pulmonary venous return
• Poor inspiration film

16
Treatment of GBS

• Drug of choice when organism has been identified
  is Pen G. 200,000U/kg/day.
• Empirical Rx Ampicillin Gent.
  -used until GBS has been
  cultured.
• Also susceptible to
  -Vancomycin
  
  -Cefotaxime
  -Ceftriaxone
  
  -Chloramphenicol

17
Treatment

• Supportive care
  hypoxia- mechanical ventilation
  
  DIC-Fresh frozen plasma
  
  Seizures-antiseizure
  medication
  -Increased
  ICP
  SIADH-Fluid restriction
  

18
Treatment of GBS Meningitis

• I.V Penicillin G
  -Infants lt7 days 250-300,000U/kg/day.
  -Infants gt 7days 300,000U/kg/day.
  
• I.V Ampicillin
  -Infantslt 7days 200-300mg/kg/day.
  -Infants gt7days 300mg/kg/day.

19
Treatment of GBS Meningitis

• Repeat lumbar puncture 24-48 hrs after
  initiation of Rx.
• Consultation with a specialist in pediatric I.D
  may be useful.

20
Duration of Rx of GBS

• Bacteremia 10days.
• Uncomplicated meningitis 14days.
• Complicated meningitis
  -Requires prolonged course,guided by
  bacteriologic report.
• Osteomyelitis,ventriculitis-4weeks.

21
Complications of GBS

• Mortality rate ranges 5-15 highest in
• very low birth wt infants
• Septic shock
• Delay in instituting antimicrobial Rx.

22
Complications of GBS

• Neurological sequelae
  
• Mental retardation
• Quadriplegia
• Hemiplegia
• Seizures
• Cortical blindness
• Bilateral deafness
• Hydrocephalus
• SIADH

23
Control Measures

• Screening based Strategy
• -All pregnant women _at_35-37weeks,
  Offer prophylaxis to GBS carriers.
  If GBS unknown _at_ onset of
  labor or ROM Rx .
• Risk factor based strategy
  -Prevention based on presence of
  intrapartum risk factor without screening.
  

24
Control Measures

• Important factors of maternal prophylaxis
• Administer intrapartum antibiotics 4 or more hrs
  before delivery
• 2 or more doses of Pen.G or Ampicillin.

25
Guidelines

• Empiric mgt of asymptomatic infants
• lt35wks whose mom received antibiotic 2 or more
  doses
• CBC,Bld Cx
• Observe for 48hrs without antibiotics.
• 
  
• gt35wks whose mom received antibiotic 2 or more
  doses
• No lab eval required
• Observe for 48hrs without antibiotics.
  
• 
  

26
Guidelines

• Empiric Mgt. (Contd.)
• For infants gt 35wks whose moms received 1 dose
• May include CBC,CRP,Bld Cx
• Observe for 48hrs.

27
Incidence rate (per 1000 live births) of
early-onset GBS disease prior to use of IPC

• Data Source CDC Publications/Thomason
  
  

28
Incidence rate (per 1000 live births) of
early-onset GBS disease by year and site

• Data Source CDC Publications/Thomason
  
  

29
Incidence rate (per 1000 live births) of
early-onset GBS disease at Thomason

• Data Source Dept. of Pediatrics, Texas tech
  
  
  
  
  
  
• 
  

30
Incidence Rate of EOGBS Disease vs. of
Hospitals with DX Prevention Policy
31
Prognosis

• Of all survivors of early or late onset GBS
  meningitis
• 25-50 have permanent neurological sequelae
• 1/3 of these patients will have severe blindness,
  deafness,and/or global developmental delay.