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Group B Streptococcus Group B Streptococcus

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

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EtiolgyEtiolgy

• 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

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EtiologyEtiology

• 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.

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EpidemiologyEpidemiology

• 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.

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EpidemiologyEpidemiology

• 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.

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

Data Source: Dept. of Pediatrics, Texas Tech

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1995 1996 1997 1998 1999 2000 2001

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EpidemiologyEpidemiology

• Direct cost of treating neonate with proven GBS – 300 million dollars/year.

• Indirect costs:• Mother’s prophylaxis?• Baby‘s treatment for suspected sepsis?

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Transmission/ Incubation period.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.

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Risk factors for ColonizationRisk factors for Colonization

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

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Early onsetEarly onset vs. vs. Late onsetLate 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.

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Early OnsetEarly Onset Vs Vs Late OnsetLate 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

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Early OnsetEarly Onset Vs Vs Late onsetLate onset

Clinical Manifestation: -Pneumonia:respiratory 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.

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Laboratory FindingsLaboratory 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.

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LABORATORY fINDINGSLABORATORY fINDINGS

Non specific tests -CBC ;Leukocytosis, Lt shift, increased band count, Increase I.T ratio >0.20,neutropenia, thrombocytopenia . -Incr. CRP. -Cxray showing pneumonia, atelectasis.

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Differential DiagnosisDifferential Diagnosis

Sepsis Aspiration pneumonia(meconium)HMDWet lung(TTNB)Total anomalous pulmonary venous

returnPoor inspiration film

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Treatment of GBSTreatment 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

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TreatmentTreatment

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

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Treatment of GBS MeningitisTreatment of GBS Meningitis

• I.V Penicillin G -Infants <7 days 250-300,000U/kg/day. -Infants > 7days 300,000U/kg/day.

• I.V Ampicillin -Infants< 7days 200-300mg/kg/day. -Infants >7days 300mg/kg/day.

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Treatment of GBS MeningitisTreatment of GBS Meningitis

• Repeat lumbar puncture 24-48 hrs after initiation of Rx.

• Consultation with a specialist in pediatric I.D may be useful.

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Duration of Rx of GBSDuration of Rx of GBS

• Bacteremia –10days.

• Uncomplicated meningitis –14days.

• Complicated meningitis -Requires prolonged course,guided by

bacteriologic report.

• Osteomyelitis,ventriculitis-4weeks.

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Complications of GBSComplications of GBS

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

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Complications of GBSComplications of GBS

Neurological sequelae: – Mental retardation

– Quadriplegia

– Hemiplegia

– Seizures

– Cortical blindness

– Bilateral deafness

– Hydrocephalus

– SIADH

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Control MeasuresControl Measures

Screening based Strategy:

-All pregnant women @35-37weeks, Offer prophylaxis to GBS carriers. If GBS unknown @ onset of labor or ROM Rx .

Risk factor based strategy: -Prevention based on presence of intrapartum risk factor without screening.

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Control MeasuresControl Measures

Important factors of maternal prophylaxis:– Administer intrapartum antibiotics 4 or

more hrs before delivery– 2 or more doses of Pen.G or Ampicillin.

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GuidelinesGuidelines

Empiric mgt of asymptomatic infants: – <35wks whose mom received antibiotic 2 or

more doses:• CBC,Bld Cx• Observe for 48hrs without antibiotics.

– >35wks whose mom received antibiotic 2 or more doses:

• No lab eval required• Observe for 48hrs without antibiotics.

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GuidelinesGuidelines

Empiric Mgt. (Contd.)– For infants > 35wks whose moms

received 1 dose: • May include CBC,CRP,Bld Cx• Observe for 48hrs.

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

Data Source: CDC Publications/Thomason

0

0.5

1

1.5

2

2.5

ATL TN SF MD TOT THOM

1993

1994

1995

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

Data Source: CDC Publications/Thomason

0

0.5

1

1.5

2

2.5

ATL TN SF MD THOM

1993

1994

1995

1998

1999

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

Data Source: Dept. of Pediatrics, Texas tech

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1995 1996 1997 1998 1999 2000 2001

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Incidence Rate of EOGBS Disease vs. % of Hospitals with DX Prevention Policy

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PrognosisPrognosis

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.