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