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MRCOG PART 2 SBAs and EMQs

Course PAID
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ESSAY 249 - GBS

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		Posted by saima gulzar S. Wed Aug 22, 2007 02:44 am
I will tell her that 25% of mothers in the UK are likely to be GBS carriers.Most of colonisation of cervix and vagina is from gastrointestinal tract reservoir.It has been frequently isolated from rectal swabs of female carriers and uretheral swabs of male partner indicating some relationship with sexual transmission. (b)GBS infection cause neonatal mortality and morbidity in form of early onset and late onset infection.Early onset GBS infection appears within 5 days of delivery and associated with neonatal septicaemia,meningitis and pneumonia & its incidence is 0.5/1000 births.Late onset GBS infection appears 1 week after delivery and associated with meningitis.In mother this infection may cause UTI,asymptomatic bacteriuria& preterm prelabour rupture of membranes. This infection also play role in preterm labour,choioamnionitis ,puerperial septicaemia and post partal endometritis. (c) At present in the UK routine screening for GBS is not recommended as it is not cost effective and numbers need to treat are more that is 7000 women need to give intrapartum antibiotic prophylaxis to prevent one neonatal death.There is also increased risk of maternal anaphylaxis reaction (sometime leading to death) associated with use of routine intrapartum antibiotic prophylaxis with penicillin .Also routine intraparum prophylaxis is associated with emergence of resistant strains of bacteria.Routine neonatal antibiotic prophylaxis may alter the the gut flora of neonate which is associated with later implication as atopy and effect on development of immune system.Selective media is required for culture that is rarely used in the UK laboratories. On the other hand routine Antenatal screening for GBS fulfilled most of the criteria of WHO screening programme.The test for screening (such as low vaginal and rectal swabs or urine samples) are easy to perform , readily available ,acceptable and cheap with high sensitivity .The carrier rate for disease is high and treatment is easily available and cheap. Several screening approaches has been proposed including bacteriological screening with swabs for all women at 35-37 weeks gestation and antibiotic prophylaxis to all carrier women .Other approach was risk based screening and antibiotic prophylaxis to women at risk such as women with previous neonatal GBS, in women with incidental finding of GBS in urine in current pregnancy,in women with PPROM >18 hours or pretem labour or fever in labour. Routine screening for GBS at present is not recommended as it is not cost effecticve and only intrapartum antibiotic prophylaxis is recommended for women with known risk factors..
		Posted by Jancy V. Wed Aug 22, 2007 02:46 am
I would tell her that 25% of women in reproductive age group have vaginal colonistion with GBS. It is an asymptomatic colonization and even if detected , treatment with antibiotics in antenatal period is not recommended. Since she is working in health services, there is all the more chance htat she has asymptomatic vaginal colonization with GBS I would tell her that GBS colonization of vagina may lead to early onset neonatal GBS, incidence being 0.5 per 1000 in UK. This infection is potentially fatal with mortality of 6% in term infants and 18% in preterm infants. However ,antenatal detection and treatment of GBS with antibiotics do not prevent neonatal sepsis. If she has risk factors like preterm labour, premature rupture of membranes > 18 hrs or intrapartum fever, she is high risk for sepsis and would be given antibiotics appropriately. Incidental detection of GBS in urine or vaginal swab in antenatal period is an indication for intrapartum penicillin prophylaxis. If allergic to penicillin, she would be given clindamycin IV. Universal or risk factor based screening for GBS is not done in UK . GBS is the commonest cause of neonatal sepsis with incidence of 0.5 per 1000 birhts and leads to mortality of 6% in term and 18% in preterm infants. Hence prevention is important. Universal screening using low vaginal and rectal swabs can be undertaken at 35-37 weeks as practiced in US and it has been shown to reduce the incidence of early onset sepsis , with no change in late onset sepsis and overall neonatal mortality rates. Another advantage of this method is that it is relatively easy, cheap and acceptable to most women. Effective antibiotic is available against GBS if detected. The disadvantage of screening is that neither universal nor risk based approach is cost effective; at least 24000 women need to be screened in order to prevent one NND due to GBS. Some women feel that antibiotic injections lead to medicalisation of labour and hence find it unacceptable. Another disadvantage is the potentially fatal anaphylaxis from antibiotic use. It does not prevent late onset sepsis. Wide spread use of antibiotic leads to development of resistant strains of bacteria. Antibiotics in neonatal period alter the fecal flora and lead to long term consequences in the immune system and development of allergy in childhood. There is no consistent policy so far regarding antenatal screening for GBS in UK. The specific culture medium for GBS is not being widely used in labs. There is no data available on the current GBS prevalence in UK. More randamised control trials need to be undertaken before screening in adopted. Hence it is justified that routine screening cannot be offered to women for GBS.
		Posted by Natalia N. Wed Aug 22, 2007 02:54 am
a. The likelihood of GBS colonisation in pregnant women is about 25%. Colonisation of genital tract occurs from gastrointestinal tract. Colonisation of genital tract is chaning, and antenatal treatment of GBS is not effective. Colonisation at 18 weeks does not predict chances of colonisation in labour when GBS is transmitted to the baby. Colonisation of rectum is more common than colonisation of vagina. The incidence of fetal colonisation if the mother is colonised is 50-70%. If woman receives antibiotics 1 hour before delivery the incidence of fetal colonisation is 46%, 2-4 hours ? 3%, and 4 ours ? 1%. b. Infection occurs in 1% of colonised infants. GBS causes early-onset infection in neonates is transmitted vertically. It is characterised by meningitis, pneumonia, septicaemia and is associated with preterm prelabour rupture of membranes (PPROM), preterm delivery, low birth weight. The mortality rate from early-onset infections is 5%. Late-onset infection (a week after birth) is mostly characterised by meningitis and has nosocomial or horizontal transmission from mothers and care-givers. GBS has maternal risks. It causes intrapartum and postpartum sepsis. It increases risk of chorioamnionitis. It is associated with increased risk of urinary tract infection and asymptomatic bacteriuria. c. The recommendation that routine screening GBS should not be offered is justified. Numbers needed to treat to prevent one case of neonatal sepsis is 700 and numbers needed to prevent one neonatal death is 7000. Therefore, practice of routine GBS screening is not cost-effective. Treatment of GBS (with IV penicillin or clindamycin in labour) has side-effects, it may cause anaphylaxis and maternal death. Identification of GBS colonisation causes unnecessary anxiety. Antibiotics cause development of resistant microorganisms. Administration of antibiotics for GBS colonisation masks diagnosis of neonatal infection. It also predisposes children mothers of which received antibiotics to development of atopy and allergy later in life. Risk based approach to the prevention of neonatal GBS infection reduces risk of this infection 30 times. It prevents 68% of cases in comparison to 86% of cases prevented by routine screening programme. This approach involves treatment of women with risk factors of GBS (previous baby affected by GBS, GBS bacteriuria in pregnancy, preterm labour, PPROM, fever in labour).
		Posted by Jancy V. Wed Aug 22, 2007 03:53 am
I would tell her that 25% of women in reproductive age group have vaginal colonistion with GBS. It is an asymptomatic colonization and even if detected , treatment with antibiotics in antenatal period is not recommended. Since she is working in health services, there is all the more chance htat she has asymptomatic vaginal colonization with GBS I would tell her that GBS colonization of vagina may lead to early onset neonatal GBS, incidence being 0.5 per 1000 in UK. This infection is potentially fatal with mortality of 6% in term infants and 18% in preterm infants. However ,antenatal detection and treatment of GBS with antibiotics do not prevent neonatal sepsis. If she has risk factors like preterm labour, premature rupture of membranes > 18 hrs or intrapartum fever, she is high risk for sepsis and would be given antibiotics appropriately. Incidental detection of GBS in urine or vaginal swab in antenatal period is an indication for intrapartum penicillin prophylaxis. If allergic to penicillin, she would be given clindamycin IV. Universal or risk factor based screening for GBS is not done in UK . GBS is the commonest cause of neonatal sepsis with incidence of 0.5 per 1000 birhts and leads to mortality of 6% in term and 18% in preterm infants. Hence prevention is important. Universal screening using low vaginal and rectal swabs can be undertaken at 35-37 weeks as practiced in US and it has been shown to reduce the incidence of early onset sepsis , with no change in late onset sepsis and overall neonatal mortality rates. Another advantage of this method is that it is relatively easy, cheap and acceptable to most women. Effective antibiotic is available against GBS if detected. The disadvantage of screening is that neither universal nor risk based approach is cost effective; at least 24000 women need to be screened in order to prevent one NND due to GBS. Some women feel that antibiotic injections lead to medicalisation of labour and hence find it unacceptable. Another disadvantage is the potentially fatal anaphylaxis from antibiotic use. It does not prevent late onset sepsis. Wide spread use of antibiotic leads to development of resistant strains of bacteria. Antibiotics in neonatal period alter the fecal flora and lead to long term consequences in the immune system and development of allergy in childhood. There is no consistent policy so far regarding antenatal screening for GBS in UK. The specific culture medium for GBS is not being widely used in labs. There is no data available on the current GBS prevalence in UK. More randamised control trials need to be undertaken before screening in adopted. Hence it is justified that routine screening cannot be offered to women for GBS.
		Posted by Natalie P C. Wed Aug 22, 2007 07:49 pm
ESSAY A I would tell her that 15-20% UK women are colonised with GBS. I would say that it is a colonisation that comes and goes so even if she has it now, she may not have it at term. It colonises the gut and genital tract but does not generally cause an infection in her antenatally unless in the urine when the bacteuria must be treated B If it is in the urine it needs treating as there is a risk of pyelonephritis and subsequent preterm labour. If it is in the genital tract at the time of delivery there are neonatal and maternal risks. Risks include prelabour rupture of membranes, preterm labour and pyrexia in labour. There is also a risk of chorioamnionitis and portpartum endometritis. Neonatal colonisation at birth is 50-75% but neonatal infection is 2-5 per 1000 live birth for early disease. Early disease includes sepsis, pneumonia, meningitis and death. Late disease is 0.5 per 1000 live births and can be meningitis and death. Risk of death itself is very low 1 in 10000 live births. C Yes I believe if is justified for the following reasons. Only 15-20% women are colonised so with this low prevalence many women received a test they do not need. It increases anxiety in women when their risk of coloisation is quite low. Even if they are colonised the risk of neonatal sepsis or death are also very low. The test is not very sensitive detecting only 40-50% carriers. Rectal swabs are better to detect colonisation but patients may not find this acceptable. As the colonisation comes and goes, a positive test at one particular time does not equate to positive colonisation at the time of delivery. There is no optimal time to screen ? if you screen later to detect those who are positive at term, you will miss the preterm labourers but if you screen to early you miss those who become colonised later and you treat women who may no longer be colonised. There is a high cost to prevent 1 neonatal sepsis or 1 neonatal death. The greater use of antibiotics can increase drug resistance and increase the risk or number of women who have anaphylaxis due to unknown allergy to benzylpenicilin. Screening or treating only those who are high risk (previous GBS baby, PPROM, PTL, pyrexia in labour, postpartum endometritis) increases your detection rate and reduces the number of women inappropriately treated. Reasons why this type of testing may not be justified is that you miss asymptomatic women who may go on to have an infected baby and perhaps women should have the choice to accept screening with its attendant risks of false positive, low sensitivity, inappropriate antibiotics, drug resistance and anaphylaxis.
		Posted by Idris O. Wed Aug 22, 2007 10:47 pm
a)I would inform her GBS is a commensal of the urogenital and GI tracts. The colonisation rate is 15-20% of all women. It is usually asymptomatic and poses no harm to the mother. It is potentially harmful to the baby during delivery. b)I would tell her the finding of GBS bacteriuria require antibiotic treatment in pregnancy with benzylpenicillin or if allergic with clindamycin. This is to prevent preterm labour and pyelonephritis. If GBS is found on hvs or rectal swab,this is usually asymptomatic and does not require treatment in pregnancy. GBS colonisation may cause PROM or labour and if PROM occurs before term prophylactic treatment with erythromycin is offered. ALL GBS colonised mothers are offered antibiotic prohylaxis in labour. This should be given at least 4h before delivery( 40-75% fetal colonisation rate) .This reduces the incidence of early onset GBS (rate of 2-3/1000) but the incidence of late onset GBS after 1wk of 0.5/1000 is unchanged. However, if the mother requires caesarean section for other obstetric reasons and has intact membrane she does not require antibiotic prophylaxis for early onset GBS but the risk of late onset GBS is unchanged. I would offer her information leaflet on GBS in pregnancy. c)GBS colonisation if undetected causes early onset NNS in 2-3/1000 women. This is associated with increased perinatal mortality and morbidity. However, the screening method by hvs at the moment is cheap but not very sensitive and sensitivity only improved by repeat testing in the third trimester. A single rectal swab is more senstive but this may be uncomfortable and may not be acceptable to the women. Urine analysis by m/c/s is offered routinely to all pregnant women and this may help the detecting rate. The carrier rate is 15-20% of women. This would subject 80% of the women without GBS to screening and the test is unreliable and not cost effective. Pregnant women with GBS on hvs would be associated with anxiety about the pregnancy as there is no treament in pregnancy. Antibiotic prophylaxis with benzylpenicillin or clindamycin in patients allergic to penicillin is offered in labour. This is effective treatment for the prevention of early onset GBS but does not affect the incidence of late onset disease. The consequences of untreated GBS carrier is not so grave as to recommend TOP as an option. Early antibiotic treatment of the babies may still reduce mortality and morbidity from GBS infection. Screening can be targeted at women with high risk factors like previous baby with neonatal GBS infection, known carrier of GBS, PPROM and pyrexia in labour. Serial hvs with a repeat screening in the third trimester may improve the detection rate. However, this may miss the low risk women and mortality and morbidity occurs in this group of women.
		Posted by Parveen Q. Thu Aug 23, 2007 05:13 am
I will tell her that GBS colonisation occurs in about 25%pregnant women. It is associated with early onset neonatal disease, which carries increase morbidity and mortality. Eradication of the genital tract colonisation is ineffective. It is not necessary to do rectal or vaginal swabs throughout pregnancy. (b)The potential consequences for the mother is in the form asympatamatic proteinuria, and if left untreated leads to pyelonephritis in 30-50%of women. The other risk is intrapartum, postpartum sepsis , which may increase maternal morbidity and mortality. In the event of PPROM, leading to chrioamnionitis. For the foetus, the risk of PTL, PROM, leading to increase perinatal morbidity and mortality. Through vertical transmission from the mother, leading to early onset disease , the prevalence of which in untreated cases is 0.5/1000 live births. It can occur within 5days and manifest in the form of pnemonia, septicemaia or meningitis. The late onset disease , which can occur through horizontal transmission from mother can occur after 1week. It leads to 20%mortality, and 50%survivors will have long term sequalae. Antibiotic prophylaxis in the form of benzyl penicillin 3gm, followed by 1.5gm iv 4hourly can be undertaken even in incidental detection in the vagina or in urine in the current pregnancy. For those allergic to penicillin, clindamycin 900mg iv 8hourly is given. To optimise efficacy it is given at the earliest onset of labour or within 2hours of delivery. There is no good evidence to support antibiotic prophylaxis if planned cesarean section is undertaken. No need to continue antibiotic in an asymptamatic women after delivery. (c)Routine antanatal screening and treatment may be disadvantageous to the woman and foetus. for the woman, in the form of antiobiotic fatal anaphylactic reaction. The medicalisation of labour may not be acceptable to some women. Development of resistent organism leading to other infection. For the foetus, similarly, development of resistent organism, leading to alteration in the fecal flora , and development of allergies in the later life. Antibitic prophylaxis prevents early disease, but does not prevent late onset disease. The risk of neonatal sepsis and mortality is not reduced. Further more, the data about the prevalence is not the latest one and the current data does not favour universal screening. No evidence that the screening is cost effective. Large number of women need to be screened and treated to prevent few neonatal infection. Selective media for isloation is not widely available. so, routine screening is not justified.
		Posted by Parveen Q. Thu Aug 23, 2007 05:22 am
correction please (b) to optimise efficacy antibiotic is given at the onset of labour and atleast 2hours before delivery.
		Posted by Mohammad H. Thu Aug 23, 2007 05:36 am
A healthy 30 year old general practitioner attends the antenatal clinic at 18 weeks gestation in her first pregnancy. She is concerned about the potential consequences of group B streptococcal (GBS) infection and requests testing. (a) What would you tell her about the likelihood of GBS colonisation? [3 marks]. (b) What would you tell her about the potential consequences of GBS colonisation? [7 marks]. (c ) Is the recommendation that routine screening for GBS should not be offered justified? (10 marks). a- GBS is a bowel commensal that colonizes the vagina in ~25% of women in the UK. b- GBS is the commonest cause of severe early onset neonatal infection with incidence of ~.5/1000 in the UK.GBS can colonise the urinary tract leading to asymptomatic bacteruria&urinary tract infection with their consequences. In patients with vaginal colonization,50% of fetuses will be colonised but only 1% will be affected with early onset group B streptococcal (EOGBS). Eighty percent of affected neonates will die and 50%of the survivors will have meningitis or neurological damage.Fetal colonisation occurs around the time of delivery.GBS can cause chorioamnionitis in patients with premature rupture of membranes. c- Routine screening would be expected to detect cases that is clonised by GBS so providing prophylactic antibiotics and decreasing the risk of EOGBS.However ,in USA where screening is universal ,the incidence of EOGBS is 0.5/1000 which the incidence in the UK without screening.Antenatal screening and prophylactic antibiotics will not necessarily prevent peripartum colonisation.It is assumed that 24,000 women would be screened to prevent one neonatal death due to EOGBS.Screening will require vaginal or anal swabs which may be not accepted by mqany women especially low risk patients. Prophylactic antibiotics has hazards as maternal severe and even fatal anaphylaxis may occur and fetal anaphylaxis also can occur.Resistant species acn develop with the widespread use of prophylactic antibiotics.The flora of the neonatal bowel may be reduced leading to affected immunity. Patients who deliver by C.S have a very low risk of EOGBS ,so it is not justifiable to receive prophylactic antibiotics.Prophylactic antibiotics is provided to high risk patients with colonisation in current pregnancy,previously affected or patients with PROM for more than 18 hours,PTD <37 weeks or fever >38c in labour.
		Posted by Sabahat S. Thu Aug 23, 2007 06:40 am
a) I will inform her that the incidence of GBS infection in UK is .5/1000. Since she is in the medical profession, there is a chance of her being infected . But even if she is found to be infected now, (at 18 wks) the infection may not be present at term when there is risk of fetal transmission. Antenatal screening for GBS is not advisable, as it is not found to be cost effective. b) GBS colonization during the antenatal period may result in asymtomatic bacteria, which if untreated, may progress to pylonephritis. It may cause fever, , vaginitis, choroamniotis ,endometritis,puerperal sepsis. She may have preterm labour, PPROM,, fever during labour. The neonate may suffer from GBS early (within 24 hours) onset infection (70 % vertical transmission) manifested as meningitis, pneumonitis, septicaemia.This has a mortality of 6/1000 in term & 18/1000 in preterm neonates. The mortality is even higher at GA less than 35 wks, being 22/1000. The morbidity is severe & rapidly progress to convulsions & death, if untreated or inadequately treated. The neonate may also suffer from late onset (after 7 days) GBS infection( not due to vertical transmission) which is due to horizontal transmission from the mother & the surroundings.. c) Routine screening for GBS is presently not justified in UK, due to several reasons. The incidence of early onset GBS in UK is .5/ 1000, routine screening at 35 ? 37 wks & widespread antibiotic prophylaxis is practiced in USA, but the incidence of the disease is the same as in the UK (where routine ANC screening & antibiotic prophylaxis is not done). The numbers needed to treat, to prevent a single case of GBS disease (600) & to prevent a single mortality from GBS disease (6000+), are so high that many women will be exposed to unnecessary screening & subsequent antibiotic prophylaxis. This will have significant financial implications & have not proved to be cost effective. The selective culture mediums used for GBS are not widely available in UK. It is possible that the woman who is screen positive during antenatal (35-37 wks) screening does not have the infection when she delivers at term.; or the contrary that she may deliver preterm ( due to GBS infection) before she could avail of the screening at 35-37 wks and the subsequent prophylaxis. The efficacy of antibiotic prophylaxis is at best only 80%. Many of the neonates will have well-established infection before antibiotic prophylaxis is started. Antibiotic prophylaxis (ampicilin or clindamycin) will expose the mother to the risk of anaphylaxis, which could be fatal, with associated neonatal risks. It will result in emergence of resistant organisms & alteration of the neonates gut flora, with the inherent risk of development of allergies due to altered commensal microorganisms in the GI tract. Some women may resent this medicalisation of labour. Even if the risk factor based approach to screening & treatment is applied, about 25% of the women will be treated to reduce the infection by 50-68%. Presently in UK the women who are high risk (preterm labor < 37 wks, have prolonged rupture of membranes > 18 hrs, have intra partum fever > 38oc has GBS bacteriuria during the present pregnancy, or have a history of a previous baby being affected by GBS infection) are offered intrapartum prophylaxis. So the current UK practice of not doing routine screening for GBS is justified, UNTIL RCT show a clear evidence of benefit of, a change in practice.
		Posted by Valerie T. Thu Aug 23, 2007 07:21 am
a) Group B Streptococcus is a bacteria that is normally lives in the body and can be located in the vagina and rectum. Group B Streptococcus colonisation is found in 25% of pregnant women. This can lead to colonisation of the baby during labour and delivery. The incidence of group B Streptococcus infection in newborn babies is 1 in 2000. I would provide her with an information leaflet. b) Group B Streptococcus colonisation may have potential maternal and fetal consequences. The maternal effects on the renal system include asymtomatic bacteriuria, urinary tract infection and pyelonephritis. It can also lead to preterm rupture of membranes, chorioamnionitis and preterm labour. The fetal effects include sepsis and fetal hypoxemia. In the neonate it can cause prematurity, respiratory distress syndrome, neonatal septicemia and meningitis. Colonisation increases the risk of perinatal mortality. c) Group B Streptococcus infection in babies is a serious cause of morbidity and mortality. The advantage of screening all women is that you would potentially identify all women with the bacteria and prevent the ill effects on the neonate. Routine screening for Group B Streptococcus can lead to many women being treated with penicillin. The disadvantage of this, is that it may result in a significant number of women having anaphylactic reactions to penicillin which may be severe in pregnancy and increase the risk of maternal and fetal morbidity and mortality. It can also lead to the development of resistant strains of bacteria. Routine screeing is done in some countries such as the USA. Currently all women with high vaginal or rectal swabs,Mid stream urine specimens that contained this bacteria, and women with a history of neonates with GBS disease are treated with antibiotics in labour.The incidence of early onset disease in newborns in the USA is similar to the incidence of the disease in the UK (0.1 in 1000) where routine screening is not performed. This shows that routine screening may be unnecessary.
		Posted by Mahmud K. Thu Aug 23, 2007 09:46 am
GBS is frequently isolated from the genital tract , lower gastrointestinal tract and urinary tract. If swabs are taken from the rectum as well as the vagina , the identification of asymptomatic carriage increase. A number of risk factors have been identified which increase the likelihood of the neonate being colonised. These include preterm rupture of membrane, prolonged rupture of membrane, fever in labour. Most carriers are asymptomatic. Fetal colonisation rate at delivery 40-70%. In newborn babies there are two types of GBS disease , early onset and late onset. GBS is the most frequent cause of Early ?onset neonatal sepsis which can progress rapidly to death. Early onset disease also present with pneumonia . Late onset disease may present with meningitis or focal infection. GBS is also a recognised cause of preterm delivery. GBS may increase risk of stillbirth and late miscarriage .In antenatal period, GBS infection rarely presents clinically. On occasion women may present with an increased vaginal discharge. GBS may also cause asymptomatic urinary tract infection and it is associated with higher risk of neonatal disease.. In the post partum period GBS can cause endometritis, sepsis, UTI and very rarely meningitis. The aim of the screening test for GBS is identify the GBS carrier so that intrapartum antibiotic prophylaxis can be offered. Intrapartum antibiotic prophylaxis has been shown to significantly reduce the risk of early onset but not the late onset disease. Approximately 25% of mothers in the UK are likely to be GBS carriers. The incidence of early-onset GBS disease in the UK in the absence of systematic screening or widespread intrapartum antibiotic prophylaxis is 0.5/1000 births.Therefore,large number of women need to be screened and also large number of colonised women need intrapartum antibiotic prophylaxis for prevent one neonatal death from GBS .Routine screening benefits are not cost effective. There are also some possible risks. These include potentially fatal anaphylaxis associated with the use of penicillin in labour.The widespred use of antibiotics is known to contribute to the development of resistant organisms. In UK there is no rapid reliable bed-side testing available for GBS screening . Selective culture media are required for optimal detection of GBS by sampling the lower vagina and rectum. This is also not cost effective. In order for clear recommendation to be made about relative benefits and risks of antenatal screening for GBS in the UK, further research in the form of RCT of current clinical practice versus bacteriological screening should ideally be performed. .
		Posted by Malar R. Fri Aug 24, 2007 03:30 am
A healthy 30 year old general practitioner attends the antenatal clinic at 18 weeks gestation in her first pregnancy. She is concerned about the potential consequences of group B streptococcal (GBS) infection and requests testing. (a) What would you tell her about the likelihood of GBS colonisation? [3 marks]. (b) What would you tell her about the potential consequences of GBS colonisation? [7 marks]. (c ) Is the recommendation that routine screening for GBS should not be offered justified? (10 marks). She should be informed that in the UK there maybe a 20-25% of asymptomatic carriage rate.She may therefore be a carrier. Mostly women who are colonised are aymptomatic. Most babies born to women carrying GBS do not have any problems. In a minority of women , GBS may cause severe morbidity and mortality in the newborn. GBS may also cause problems such as sepsis in the mother. Babies most prone to GBS infections are those born preterm or after prolonged ruptured membranes. Also pyrexia in labour may expose the baby to the infection. If she has a previous baby affected by GBS, there is a risk of the current baby being infected at birth and being unwell due to GBS. Also if she has GBS in her urine , there is a higher risk of infection to the baby at birth. Babies affected by GBS may have immediate problems after delivery such as respiratory distress and septicaemia.Babies can also have late onset GBS after 7-10 days of birth. This may present as pyrexia and meningitis. Both early and late onset GBS have high risk of morbidity and mortality in the baby. The benefits of screening include reducing perinatal morbidity and mortality due to GBS.This will also minimise cost as many days spent in special care baby unit will be saved. However there are problems with routine screening. The tests used currently do not have very good sensitivity for GBS and cases may be missed and mislabelled as low risk. The exact timing to screen is also uncertain as women may not carry the organism all the time. This will also lead to increased cost of screening and treating everyone. As GBS only affects a small number of babies but is carried by many women, it might not be cost effective.Extra resources will have to be put in place to check results and act on them. Also treatment may bring antibiotic resistance or cause anaphylaxis to mothers. Screening is invasive and may not be acceptable to all women. Treating all women medicalises their pregnancy and may not be acceptable. Preterm babies who are most vulnerable and have highest morbidity and mortality form GBS may still not be saved as screening may miss them if labour happens before screening. Therefore maybe screening should be targetted to high risk cases as being universal.