5/18/20151 group b streptococcus group b streptococcus adunni morohunfola, m.d. dept. of pediatrics,...
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04/18/23 1
Group B Streptococcus Group B Streptococcus
Adunni Morohunfola, M.D.Dept. of Pediatrics, Texas Tech
04/18/23 2
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
04/18/23 3
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.
04/18/23 4
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.
04/18/23 5
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.
04/18/23 6
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
04/18/23 7
EpidemiologyEpidemiology
• Direct cost of treating neonate with proven GBS – 300 million dollars/year.
• Indirect costs:• Mother’s prophylaxis?• Baby‘s treatment for suspected sepsis?
04/18/23 8
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.
04/18/23 9
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
04/18/23 10
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.
04/18/23 11
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
04/18/23 12
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.
04/18/23 13
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.
04/18/23 14
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.
04/18/23 15
Differential DiagnosisDifferential Diagnosis
Sepsis Aspiration pneumonia(meconium)HMDWet lung(TTNB)Total anomalous pulmonary venous
returnPoor inspiration film
04/18/23 16
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
04/18/23 17
TreatmentTreatment
Supportive care hypoxia- mechanical ventilation DIC-Fresh frozen plasma Seizures-antiseizure medication -Increased ICP SIADH-Fluid restriction
04/18/23 18
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.
04/18/23 19
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.
04/18/23 20
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.
04/18/23 21
Complications of GBSComplications of GBS
Mortality rate ranges 5-15% highest in:– very low birth wt infants– Septic shock– Delay in instituting antimicrobial Rx.
04/18/23 22
Complications of GBSComplications of GBS
Neurological sequelae: – Mental retardation
– Quadriplegia
– Hemiplegia
– Seizures
– Cortical blindness
– Bilateral deafness
– Hydrocephalus
– SIADH
04/18/23 23
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.
04/18/23 24
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.
04/18/23 25
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.
04/18/23 26
GuidelinesGuidelines
Empiric Mgt. (Contd.)– For infants > 35wks whose moms
received 1 dose: • May include CBC,CRP,Bld Cx• Observe for 48hrs.
04/18/23 27
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
04/18/23 28
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
04/18/23 29
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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