Objectives
Describe the epidemiology of Group B Update: Perinatal Group B Streptococcus, including incidence and Streptococcal Disease risk factors. Discuss the latest treatment & Michele B. Zitzmann, M.H.S., MT(ASCP) prevention guidelines for perinatal LSUHSC Dept. of Clinical Laboratory Sciences Group B streptococcal disease. New Orleans CLPC Spring, 2017
Group B Streptococcus (GBS) Group B Streptococcus (GBS)
Leading bacterial infection associated with Currently: Remains the leading illness and death among newborns in the infectious cause of morbidity & mortality U.S. among newborns in the U.S. • Prior to active prevention activities (1996): – CDC estimates 1,200 cases of GBS –8,000 – 12,000 cases of GBS sepsis & sepsis & meningitis in newborns each year meningitis in newborns each year (U.S.) (U.S.) –Approximately 2,000 deaths – Approximately 70% of cases are among –Direct medical costs: $300 million/year babies born at term (>37 weeks gestation)
Group B Streptococcus Gram Stain
Streptococcus agalactiae Gram positive cocci – Short chains in clinical specimens – Longer chains in culture Blood Agar plate – Gray-white mucoid colonies – Small zone of beta hemolysis
1 S. agalactiae: Blood Agar Plate Beta-Hemolysis
Streptococcus agalactiae CAMP test
Laboratory Tests: Used to presumptively identify group B – Catalase: Negative streptococci – 6.5% NaCl: No growth Named after the individuals who discovered the reaction – CAMP test: Positive –Christie, Atkins, & Munch-Petersen – Bile Esculin: Negative Staphylococcus aureus is inoculated onto blood – Hippurate hydrolysis: Positive agar plate Unknown streptococcal isolate inoculated perpendicularly to S. aureus inoculum
Positive CAMP test Positive & Negative CAMP test
2 Hippurate Hydrolysis Lancefield Classification
Differentiates S. agalactiae from other Developed in the 1930’s beta-hemolytic streptococci Rebecca Lancefield Inoculate sodium hippurate with colony; Differentiation of C carbohydrate in cell incubate 2 hours at 35oC; add ninhydrin wall reagent (indicator); incubate 10-15 min Streptococcus agalactiae – Group B Deep purple color = positive Only one organism in Group B category result Names used interchangeably
Schematic Representation: Source & Transmission Streptococcal Cell Wall Normal flora of bowel, vagina, or throat Many “carriers” of GBS (asymptomatic) 10 - 30% of all pregnant women carry GBS in the rectum or vagina Fetus may come into contact with GBS before or during birth (vertical transmission) Cesarean section does NOT eliminate risk
Maternal to Infant Transmission Clinical Disease
If mother carries GBS: Sepsis – most dramatic & devastating – 1 of every 100-200 babies will be affected complication • 1 in 4,000 chance if IAP is administered Pneumonia - early-onset only; 0-5 days – 80% of the cases occur in the first week of Meningitis – can be early-onset or late- life (Early-onset disease – EOD) onset (5-90 days) – Most cases apparent a few hours after birth Neurologic - hearing and/or visual loss; – Premature babies are more susceptible impaired mental abilities
3 Signs & Symptoms – Early Onset
Asymptomatic at birth Within first 24 hours of life: – Tachypnea – Mottling of skin – Lethargy – Hypotension – Irritability – Decreased feeding – Jaundice – Cyanosis 60 – 80% of infections occur within 12 hours of life Mechanical ventilation often required
GBS Disease in Infants
90 80 70 60 50 40 30 20
Percent of cases of Percent 10 0 < 1 1-3 1234567891011 wk wk Age (months)
Early-Onset Risk Factors for Early-Onset Neonatal GBS Disease GBS Disease
90 Maternal GBS colonization – primary risk 80 70 Obstetric: prolonged rupture of 60 50 membranes (>18 hours), preterm labor 40 (<37 weeks), intrapartum fever (100.4o F) 30 20 Percent of cases Previous infant with GBS disease 10 0 Demographic (age < 20 yrs, African- 0123456 American) Age (days)
4 Obstetric Risk Factors Among Women with GBS Infants Prevention Strategies: 1992-96
n = 245 American College of Ob & Gyn (ACOG) – No prenatal screening * no obstetric risk – Prophylaxis for women with OB risk factors factors * obstetric risk American Academy of Pediatrics (AAP) 46% factors – Universal prenatal screening 54% – Prophylaxis for carriers with OB risk factors EITHER approach expected to prevent * premature < 37 wk, ROM > 18 hr, temp > 100.4o F (38o C) 60-75% of early-onset disease
Prevention: Intrapartum Antibiotic Impact of Prevention Early-Onset GBS Disease by Year and Prophylaxis (IAP) Percent Hospitals with a GBS Policy -- Atlanta, GA
ACOG Tech Bulletin AAP Guidelines Consensus Antibiotics administered IV after onset 2.5 60
Meeting y of labor or membrane rupture, but 2 50 before delivery Provider Practice Hospital 40 1.5 Survey Site Visits Most likely method for preventing GBS 30 1 CDC Draft Penicillin is drug of choice; ampicillin Guidelines (Dec) 20 Consensus 0.5 10 also used Guidelines (May) % Hospitals with GBS Polic % Hospitals GBS with Cases per 1000 live births per Cases 0 0 1989 1990 1991 1992 1993 1994 1995 1996 1997 Year
Barriers to Effective GBS Prevention Statistics Disease Prevention - Initially
CDC and Prevention’s surveillance data 63% of clinicians collected prenatal indicate that early-onset GBS disease cultures for GBS declined by 65% between 1993 and 1998 BUT: (in areas with continuous data) 91% used suboptimal sites (not vag/rectal) In 1998, an estimated 3,900 neonatal Few clinicians knew what media their labs infections and 200 deaths were prevented used <10% of 200 labs surveyed were using optimal media (selective broth)
Jafari et al., Pediatr Infect Dis J 1995;14:662-7. Whitney et al., OB GYN 1997;89:28-32.
5 Women Screened for GBS Prevention Strategies: 2002 (1998-9) vs. (2003-4)
Universal culture screening for all pregnant women at 35-37 weeks gestation Implementation was rapid & widespread However, only 50.3% of women delivering preterm had known GBS status Only 63.4% received prophylaxis
Women Who Received IAP Prevention Strategy: 2010 (1998-9) vs. (2003-4) Risk factors: Give • Previous infant w/GBS disease YES intrapartum • GBS bacteriuria this pregnancy penicillin • Delivery < 37 wks gestation NO GBS+ Give Collect rectal & vaginal swab at 35-37 wks intrapartum Not done, incomplete, or penicillin results unknown GBS- Risk factors: • Intrapartum fever > 100.4oF YES Give • ROM > 18 hrs intrapartum penicillin NO No intrapartum prophylaxis needed
CDC’s Recommendations for Advantages of Prevention Strategy Prenatal GBS Cultures
Optimizes prenatal screening Optimize cultures: – Fewer false negatives Site: vagina and rectum – Less pressure on physicians to treat – Single swab or two swabs Antibiotics to all GBS carriers – Through anal sphincter – Antibiotics start earlier before development Cervical, perianal, & perineal – NOT of risk factors acceptable – Adequate time for antibiotic effectiveness Timing: 35 to 37 weeks Processing: selective broth medium
6 Specimen Transport
Inoculate swabs into non-nutritive transport medium – Commercially available (Stuart’s or Amie’s) Specimens in media may remain viable at RT for up to 4 days, however… – Results most sensitive when processed within 24 hours & refrigerated Specimens should be properly labeled – GBS specimen, penicillin allergy status
Laboratory Testing Laboratory Testing
Inoculate swabs into selective broth Pigmented enrichment broth – Todd-Hewitt broth with nalidixic acid – StrepB Carrot Broth (15 µg/ml) and EITHER colistin (10 µg/ml) or gentamicin (8 µg/ml) – Commercially: SBM or LIM broth Incubate broth 18-24 h. Subculture to sheep blood agar plate
Laboratory Testing continued Slide Agglutination Tests
Inspect and ID suggestive organisms – B-hemolytic or nonhemolytic, Gram+, catalase- If GBS not identified after 18-24h on sheep BAP, reincubate and inspect at 48h Various GBS Ag detection tests (slide agglutination, genetic probes, fluorescent antibodies) may be used for specific identification or CAMP test for presumptive identification
7 Results: Agglutination Commercial Tests PCR (Nucleic acid amplification tests – NAAT)
Can be used for GBS screening at 35-37 weeks if performed from an enrichment broth (incubated for 18-24 hours) Cannot be performed directly from vaginal-rectal swab unless woman with unknown GBS status presents in active labor & has no risk factors A positive agglutination A negative agglutination GBS is present GBS is not present
Photo courtesy of Dr. Richard Facklam, CDC
Laboratory Testing - Urine
GBS bacteriuria – A marker for heavy colonization – A risk factor for having an infant with early- onset GBS disease – Colony count cutoff of 104 cfu/mL or higher • New guidelines • Prevents burden of reporting all colony counts
GBS Carriage by Culture Site
Women in Vagina (%) Anorectum Both study (#) (%) (%) 789 10 18 21
94 18 28 31
301 11 14 18
8 GBS Carriage by Culture Method Intrapartum Prophylaxis
Women in Selective Blood agar Penicillin study (#) broth (%) plate (%) – 5 million units IV load, then 2.5 million units IV every 4h until delivery 166 34 14 Ampicillin – 2 g IV load, then 1g IV every 4h until delivery 952 17 9 – Acceptable alternative, but broader spectrum may select for resistant organisms Penicillin allergy 383 20 13 – Clindamycin or Erythromycin (increase in resistance) – Vancomycin - if resistant
Timing of Intrapartum Ampicillin Diagnostic Evaluation of Infants and Transmission of GBS Born to Mothers with IAP
Interval between No. of GBS No. (%) GBS Full Evaluation Ampicillin and carrier mothers colonized babies – CBC & Differential birth – Blood culture Controls 209 98 (47) (no Ampicillin) – +/- Chest X-ray < 1 hour 30 13 (43) – +/- Lumbar puncture 1-2 hours 36 7 (19) Limited Evaluation – CBC & Differential 2-4 hours 80 2 (2.4) – Blood culture >4 hours 105 1 (0.9)
Sample Algorithm for Management of Newborn if Maternal IAP Case Study #1
Maternal IAP for GBS? 28 year old female Yes • Full diagnostics evaluation Symptoms of sepsis in newborn? • Empiric therapy First pregnancy No < 35 wks Vaginally delivers 5 pound, 15 ounce Gestational age • Limited evaluation • Observe at least 48 hrs male 35 wks+ • If sepsis suspected, full Duration of maternal < 4 hrs or diagnostic evaluation and 37 weeks gestation IAP before delivery < 2 doses empiric therapy Normal apgar scores at birth >4 hrs or >2 doses Mother & baby discharged 24 hours • No evaluation • No therapy later • Observe at least 48 hrs
9 Case Study #1 Case Study #1
24 hours after discharge (48 hours after Laboratory tests were ordered: birth): – Urine culture (suprapubic aspiration) – Difficulty nursing and breathing – Blood cultures (from 2 different sites) – Lethargic – CSF culture – Irritable – Gram stains on all fluids Baby brought to emergency room – Direct Antigen Test (DAT) on CSF and – Fever urine – Hypotension – Ventilator
Case Study #1 Case Study #1
Laboratory results: Baby treated successfully with Penicillin – CSF Gram stain Future pregnancies: • Gram positive cocci in chains – Risk factor category – CSF Culture – Automatic Intrapartum Prophylaxis before • Group B Streptococcus delivery – Direct Antigen Test – Delay discharge of infant for 48 hours • Group B Streptococcus
Case Study #2 : 1995-96 Case Study #2 : 1995-96
27 year old female At 39 weeks gestation, vaginal culture reveals growth of normal flora First pregnancy 6 days later, female is admitted to hospital for At 32 weeks gestation, urine culture labor induction reveals 10,000 – 50,000 CFU/mL beta- Vaginal culture is repeated: negative hemolytic streptococci, Group B 7 pound, 4 ounce female is vaginally delivered; apgar score = 9 Ob/Gyn prescribes 250 mg oral Mother & baby discharged 48 hours later Amoxicillin 2x for 10 days No complications with GBS
10 Case Study #2 : 1998-99 Case Study #2 : 1998-99
30 year old female Ob/Gyn prescribes 250 mg oral Second pregnancy Amoxicillin 2x for 10 days Previous GBS carrier; infant not At 36 weeks gestation, vaginal culture affected repeated; reveals no GBS present At 13 weeks gestation, vaginal culture Admission to hospital 30 days later for reveals no GBS present labor induction At 21 weeks gestation, urine culture reveals 1,000 – 10,000 CFU/mL GBS
Case Study #2 : 1998-99 Case Study #3
Upon admission (8:00 am): 1938 – IV Penicillin G (5 mu) administered 6 month old male – Four hours later (12:00 pm) : Diagnosed with streptococcal meningitis • Dosage lowered to 2.5 mu Grave prognosis – At 3:07 pm: • 8 pound male vaginally delivered; apgar score = 9 7 other babies in isolation with same – Mother & baby discharged 48 hours later diagnosis – No complications with GBS
Case study #3 Case Study #3
Dr. offered “experimental treatment” “Experimental Treatment” Mother had to sign consent – Treatment could: • Kill baby • Have no effect • Treat disease Penicillin Only 1 of 8 mothers signed consent Treated baby survived; other 7 died
11 Case Study #3 Case Study #3
Penicillin Age 21 (after MT school) – Very experimental in 1938 Returned to hospital & met Dr. that – Had not gone to clinical trials / no studies treated him yet Dr. located patient’s medical chart – Extremely hard to acquire Cause of patient’s GBS: – Breach baby – Long labor • ROM >18 hours
The Advocate, May 16, 2001 The Advocate, May 16, 2001
“Child gets $107.8 million malpractice However, award” – Test was ordered a day later than should – 10 year old male have been – Brain damage due to delayed treatment for – Delay of one day in returning test results bacterial meningitis from lab (sent out) – 1990, New York hospital – Another 24 hours elapsed before patient – Test result showed that mother was was given antibiotics positive for GBS Jury ruled in favor of patient
Case Study #4 Case Study #4
Woman delivered baby who developed So, what happened??? severe GBS disease Medical records revealed the collection site Remembered being cultured for GBS & was the cervix results were negative – Suboptimal site Attorney subpoenaed her medical records – Should be rejected & physician notified Indicated patient was screened for GBS in Physician was sued for inappropriate site 35th & 37th week of pregnancy collection Results were negative Hospital sued for accepting & processing
the specimen Medical Laboratory Observer, April 1, 2012
12 Concerns with Prophylaxis Concerns with Prophylaxis
Adverse effects from antibiotics Antimicrobial-resistant pathogens – Mild allergic reactions – 27% of pregnant women in U.S. receive – Anaphylaxis antibiotics during labor & delivery – Consequences for newborn treatment – 15% of GBS isolates resistant to Clindamycin (observe for 48 hours) or Erythromycin (no longer recommended w/o susceptibility testing) – Ampicillin-resistant Escherichia coli is increasing as cause of neonatal sepsis due to GBS-associated IAP
Possible Solutions Possible Solutions
Vaginal Disinfectants Vaccine development – Less invasive approach – No licensed vaccine currently available – Chlorhexidine investigated in randomised – Clinical trials are in progress trial in Sweden • Healthy, nonpregnant adults • Have shown vaccines to be well tolerated and – Less effective than antibiotic prophylaxis immunogenic – Does not lead to an increase in resistant pathogens – Clinical trials have found no protection against early-onset GBS disease - 2014
Concerns about Vaccination Vaccination During Pregnancy
Vaccination during pregnancy Most women reluctant to accept vaccine Optimal timing of vaccination during pregnancy Proposed target group: include non- – Warned to avoid smoking, alcohol & drugs pregnant women and even adolescent – Concerned about adverse effects of girls vaccine on developing fetus Shift in serotypes of strains causing GBS disease
13 Timing of Vaccination Proposed Target Group
Timing is crucial to minimize potential Addition of GBS vaccine to adolescent harm to fetus while allowing adequate series (when booster doses are time for GBS antibodies to be produced administered) – Duration of protection is unknown Health care professionals agree that rd – Need to protect women over all of their early in 3 trimester is most appropriate reproductive years time to vaccinate (low risk to fetus; – Many booster doses may be necessary and enough time to produce antibodies & complicate vaccination programs cross placenta) – Many countries do not immunize at this age
Other Suggestions: Natural Other Suggestions: Natural Remedies Remedies
Boost competitive & healthy bacteria No studies regarding the effectiveness – Probiotics (yogurt & aged cheeses) of these remedies Boost the immune system However, many women have – Avoid sugars & refined carbohydrates experienced a reversal from positive to – Increase vitamin C and D negative cultures for GBS after following – Increase proteins & vegetables in diet one or more of these remedies Kill the bacteria Many websites with suggestions of – Garlic, tea tree oil, colloidal silver herbal remedies to prevent GBS
Organizations Endorsing the 2010 GBS Guidelines
American College of Obstetricians & Gynecologists 2010 Revised Guidelines American Academy of Pediatrics American College of Nurse-Midwives MMWR, Vol. 59 American Academy of Family (RR-10) Nov. 19, 2010 Physicians American Society for Microbiology
14 Major Differences in New Minor Differences in New Guidelines Guidelines
Expanded options for lab detection of Recommendations for IAP agents to GBS, including use of pigmented media promote the most appropriate antibiotic & PCR assays for penicillin-allergic women Revised colony count threshold for labs (clindamycin & erythromycin) to report GBS in urine of pregnant Penicillin dosing changed to facilitate women the implementation in facilities with different pre-packaged penicillin products
What Can You Do to Help? Educational Methods
Make sure your OB, Peds, and Communication between Ob/Gyn and Microbiology colleagues keep up with patient the new guidelines Public Awareness Ensure your lab is using selective broth – Literature (brochures, advertising, posters) medium – Videos Plan steps needed for implementation in – Web Sites your facility
Brochures Posters
Pre-natal Facilities
15 Posters Web Sites
Labor & CDC's GBS Internet page Delivery – http://www.cdc.gov/groupbstrep
GBS Association home page – http://www.groupbstrep.org Non-profit organization formed in June, 1990 by parents whose babies died from GBS
Podcasts e-cards
Pinterest: July is GBS Prevent Group B Strep App Awareness Month
16 Strepelle Home to Lab Test Kit
Only available in United Kingdom Two swabs collected by pregnant female (vaginal & rectal) Swabs mailed to lab in transport gel Results in 3 days Cost $39.99
Key GBS Resources
MMWR 2010;59 (No. RR-10):1-36 CDC's GBS Internet page – http://www.cdc.gov/groupbstrep GBS Association home page – http://www.groupbstrep.org
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