perinatal infections bacterial. background bacterial infections are not associated with problems...
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Perinatal infections
Bacterial
Background
Bacterial infections are not associated with problems related to organogenesis.Maternal immunosuppression during pregnancy can make the course of these infections worse.Bacterial infections are associated with poor pregnancy outcomes such as preterm birth, low birth weight, and stillbirth
Bacterial infections to be discussed
Group A Streptococcus
Listeriosis
Gonorrhea
Chlamydia
Genital Mycoplasma, ureaplasma
Group B Streptococcus
Group A Streptococcus
Background
Group A Streptococcus causes a wide variety of diseases:
Bacterial pharyngitisImpetigo
Scarlet feverNecrotizing fascititis
Streptococcal toxic shock syndromeThe most common etiologic agent is Streptococcus pyogenes.
Background cont.
Streptococcus pyogenes is divided into serotypes based on the type of M protein present on the bacteria.In addition to M proteins the other significant virulence factor is streptococcal phylogenic exotoxins (SPE).SPE acts as a superantigen. Causing a more significant infection.These streptococcal bacteria may be recovered from skin or mucous membranes of asymptomatic colonized patients.
Background cont.
The bacteria enter the body through the skin, mucosa, pharynx, and vagina.The infections can be suppurative or nonsuppurative.During pregnancy, the most significant infections caused by Group A streptococcus are:
Bacteremia without an obvious source of infectionEndometritis
Streptococcal toxic shock syndromeNecrotizing fasciitis
All of these diseases are more common during the postpartum period.
Diagnosis
Group A streptococcus can be easily cultured from infected sites.
However, in clinical situations caused by the more virulent forms of Group A streptococcus treatment needs to be started before the bacteria will grow in culture.
Fever is the most common presenting sign.
20% of patients will have “flu-like” symptoms.
Diagnosis cont.
Signs of possible necrotizing fasciitis:
Sudden onset of severe pain at the incision site that is out of proportion to the physical findings.
A thin ,watery, nonmalodorous discharge.
In order to confirm the diagnosis the wound must be opened and debrided.
Sudden onset of hypotension and shock, think about Streptococcus toxic shock syndrome.
Fetal risks
Maternal Group A Streptococcus disease can be associated with stillbirth.Neonatal invasive Group A streptococcus disease has been reported. The mortality rate is 30%. 50% of these infants are infected within 1 week of birth. This suggests vertical transmission from an infected mother.Neonatal Group A streptococcus disease presents as:
OmphalitisCellulitis
MenengitisSepsis
Fasciitis
Management
Most patients present in the immediate postpartum period.
Broad spectrum antibiotics should be utilized in the treatment of fever within the first 24-48 hours of delivery.
A cephalosporin or broad spectrum penicillin would be appropriate.
Listeriosis
Background
The organism casing the infection is Listeria monocytogenes.The most common infective sources are:
Soft cheeseOther milk products
Deli meatsOutcomes of pregnancies infected with listeria vary
Background cont.
There is a high incidence of spontaneous abortion and stillbirth in pregnancies complicated by listeriosis.
The worst prognosis occurred in pregnancies where the mother developed meningitis.
Diagnosis
Listeriosis presents with “flu-like” symptoms.
The average duration of symptoms prior to diagnosis is 6 days.
29% of patients are asymptomatic
Rarely listeriosis may cause meningitis and sepsis.
Listeria can be grown in routine culture media.
Diagnosis depends on a high degree of clinical suspicion.
Fetal risks
Transmission to the fetus is either through ascending infection from the vagina or transplacental secondary to maternal bacteremia.Neonatal listeriosis presents as:
Respiratory distressFever
Neurologic symptomsSkin rash
AsymptomaticSimilar to Group B strep there is early onset and late onset disease in the neonate.
Management
The primary management is prevention.In pregnant women infected with listeria the primary therapy is Ampicillin 2 grams IV qid for 10-14 days.In penicillin allergic women Bactrim 20 mg/kg/day IV divided into 4 daily doses.Other second line therapeutic agents are vancomycin, erythromycin, or carbapenems.Cephalosporins are not effective against listeria.
Prevention
Do not eat hot dogs, luncheon meats, or deli meats unless they are reheated until steaming hot.Do not eat soft cheeses such as feta, brie, camembert, blue cheese and Mexican style “queso blanco fresco.”Hard cheese or soft pasteurized cheeses are safe.Do not eat refrigerated pate or meat spreads.Do not eat refrigerated smoked seafood unless it is an ingredient in a cooked dish.Do not drink raw (unpasteurized) milk or eat foods that contain unpasteurized milk.
Gonorrhea
Background
Gonorrhea is caused by the bacteria Neisseria gonorrhea.The prevalence in pregnancy varies depending on the population from, 0.5%-7.4%.Risk factors include:
Multiple sexual partnersYoung age
Nonwhite raceLow socioeconomic status
unmarried
Diagnosis
Up to 80% of women with gonoccocal infections of the cervix are asymptomatic.Gonoccocal cervicitis is associated with:
PPROMPreterm labor
ChorioamnionitisEndometritis
Acute salpingitis may rarely occur in the first trimester but is unlikely to occur after the first trimester because the pregnancy prevents ascending infection.Disseminated gonococcal infection can also occur in pregnancy.Diagnosis is made by DNA assay or culture.
Fetal risks
The main risks to the fetus are secondary to complications in the mother causing preterm delivery.
Infants delivered to mothers acutely infected with gonorrhea are at risk for gonococcal ophthalmia nonatorum.
40% of infants who do not receive ocular prophylaxis are at risk for ophthalmologic complications when the mother is infected.
Management
Uncomplicated gonorrhea infections:Cefixime 400mg PO in a single doseCeftriaxone 125mg IM in single dose
Spectinomycin 2 gm IM in single doseDisseminated gonococcal infection hospitalization with parenteral antibiotics:
Ceftriaxone 1 gm IM or IV qdCeftizoxime 1 gm IV tidCefotzxime 1 gm IV tid
Parenteral antibiotics are continued until symptoms resolve.
Chlamydia
Background
Chlamydial infection is caused by the organism Chlamydia trachomatis.The prevalence of infection in pregnant women ranges from 2-37%, with the average estimate of 5-7%.Risk factors for cervical infection with chlamydia include:
Young ageUnmarried mothers
Multiple sexual partnersPrevious history of sexually transmitted diseases.
Diagnosis
The majority of infected women are asymptomatic.The diagnosis is made by culture or DNA detection.The urine or cervical secretions can be used for testing.Because of the risk of preterm delivery in infected mothers screening and treatment in pregnancy is indicated.
Fetal risks
The major risk to the fetus is related to early delivery due to maternal infection.
50-60% of neonates delivered vaginally to women with chlamydial cervicitis will be colonized with chlamydia.
This colonization can cause conjunctivitis and pneumonia in the newborn.
Management
The treatment of chlamydial cervicitis in pregnancy includes:
Azithromycin 1 gram PO in one doseErythromcin ethylsuccinate 800mg PO qid for 7
daysErythromycin base 500mg PO qid for 7 days
Alternative therapy is Amoxicillin 500mg PO tid for 7 days
The sexual partners should be tested and treated.
Genital mycoplasma and ureaplasma
Background
The cervicitis in this disease entity is caused by Mycoplasma hominis and Ureaplasma urealyticum.These organisms have been associated with:
Septic abortionPostpartum endomyometritis
Preterm laborChorioamnionitis
Diagnosis
Culture of cervical secretions in infected women.
Routine culture and treatment for these bacteria is controversial.
Fetal risks
The risk to the fetus is related to preterm delivery and the complications of prematurity and low birth weight.
Management
Routine screening and treatment for these bacteria is controversial.
Ureaplasma is sensitive to erythromycin.
Mycoplasma is resistant to erythromycin but sensitive to clindamycin.
Group B Streptococcus (GBS)
Background
In the 1970’s GBS emerged as the leading cause of neonatal morbidity and mortality in the USA.
In the early 1980’s clinical trials showed that IV antibiotics given during labor to “at risk” women could prevent early onset disease in the newborns.
Background cont.
In the 1990’s the first guidelines were issued by the CDC, ACOG, AAP. These guidelines recommended one of 2 approaches:
A risk based approachA culture based screening approach
In 2002 these guidelines were updated to the ones we use today.
MMWR.51(RR-11):1-23,2002
Differences between the 1996 and 2002 guidelines
Recommendation of universal prenatal culture-based screening for the vagina and rectal GBS colonization of all pregnant women at 35-37 weeks’ gestation.Updated prophylaxis regimens for women with penicillin allergy.Detailed instruction on prenatal specimen collection and expanded methods of GBS culture processing, including instructions on susceptibility testing.
MMWR,51(RR-11);1-23.2002.
Differences cont
Recommendations against routine intrapartum antibiotic prophylaxis for GBS-colonized women undergoing planned cesarean deliveries who have not begun labor or had ROM.
A suggested algorithm for management of patients with threatened preterm delivery .
An updated algorithm for management of newborns exposed to intrapartum antibiotic prophylaxis.
MMWR.51(RR-11);1-23.2002
Similarities between the 1996 and 2002 guidelines
Penicillin remains the first-line agent for intrapartum antibiotic prophylaxis, with ampicillin an acceptable alternative.Women whose culture results are unknown at the time of delivery should be managed according to the risk-based approach; the obstetric risk factors remain unchanged:
Delivery <37 weeks gestationDuration of membranes rupture >18 hours
Temperature>100.4°F
MMWR 51(RR-11);1-23.2002.
Similarities cont.
Women with negative vaginal and rectal GBS screening within 5 weeks of delivery do not require intrapartum antimicrobial prophylaxis for GBS even if obstetric risk factors develop.\Women with GBS bacteriuria in any concentration during their current pregnancy or who previously gave birth to an infant with GBS disease should receive intrapartum antimicrobial prophylaxis. In the absence of GBS urinary tract infection, antimicrobial agents should not be used before the intrapartum period to treat asymptomatic GBS colonization.
GBS colonization
Natural reservoir is gastrointestinal tract.
10-30% of pregnant women are colonized with GBS in the vagina or rectum.
Maternal colonization is the major risk factor for early-onset disease in infants.
Vertical transmission primarily occurs after the onset of labor or ROM.
Additional risk factors for early onset GBS disease
Gestational age <37 completed weeks
Longer duration of ROM
Intraamniotic infection
Young maternal age
Black race
Hispanic race
Algorithm for universal screening
Resistance to GBS
To date there is no confirmed resistance to Penicillin or ampicillin.Penicillin is the drug of choice with ampicillin an acceptable alternative (at Overlook we use Ampicillin as the agent of choice)Resistance to other agents in penicillin allergic women:
Erythromycin-7-25%Clindamycin-3-15%
Vancomycin use should be reserved for known resistant strains to the other 2 agents listed above
Recommended intrapartum antibiotic prophylaxis
Algorithm for threatened preterm delivery
Algorithm for management of newborns exposed to antibiotics