US Pharm. 2013;38(9):HS12-HS16.
ABSTRACT: Many different types of infections can occur during
pregnancy. Common infections include sexually transmitted diseases
(syphilis, gonorrhea, chlamydia, herpes), urinary tract infections,
group B streptococcal disease, listeriosis, and toxoplasmosis. A number
of antimicrobial therapy regimens may be used during pregnancy.
Pharmacists are in a key position to improve outcomes for pregnant women
with any of these infections through recommendations for antimicrobial
therapy, monitoring for adverse effects, prevention of drug
interactions, and counseling on adherence. Counseling points for
pregnant women include appropriate preventive measures, such as
An infection that occurs during pregnancy not only may cause harm to
the mother, but may also affect her fetus (or newborn) or her partner.1
This article focuses on selected infections that may occur during
pregnancy, including sexually transmitted diseases (STDs), urinary tract
infections (UTIs), group B streptococcal disease (GBSD), listeriosis,
Syphilis: A bacterial infection caused by Treponema pallidum, syphilis affects approximately 2 million pregnant women worldwide.2
If untreated during pregnancy, syphilis can cause spontaneous abortion,
late-term stillbirth, low birthweight, neonatal death, or congenital
Since early identification of infection is essential to prevent fetal
harm and complications, it is recommended that all pregnant women be
routinely screened with a serologic test for syphilis at the first
prenatal visit, with repeat testing during the third trimester and at
delivery for those who remain at increased risk for infection.1
Parenteral penicillin G (PCG) is the only agent with documented
efficacy against syphilis during pregnancy. Therefore, all pregnant
women with syphilis should be treated with PCG according to stage of
infection (TABLE 1). Desensitization is recommended for patients who are allergic to penicillin.1
The Jarisch-Herxheimer reaction (fever, chills, myalgia, headache,
hypotension, and tachycardia) occurs in approximately 45% of pregnant
women treated for syphilis.3 Although this reaction typically
starts within hours of treatment and resolves 24 to 36 hours later, it
can cause severe uterine contractions, premature labor, or fetal
distress during the second half of pregnancy.2,3 Therefore,
pregnant women should be counseled to seek immediate medical attention
after syphilis treatment if fever, contractions, or decreased fetal
Gonorrhea and Chlamydia: Gonorrhea, a bacterial infection caused by Neisseria gonorrhoeae, affects about 13,000 pregnant women annually.4 Chlamydia, caused by the bacterium Chlamydia trachomatis, is responsible for infections in approximately 100,000 pregnant women each year.4
If untreated during pregnancy, these infections can cause premature
labor, uterine infection, or congenital infection in the form of
conjunctivitis, pneumonia, or disseminated disease.4,5
To prevent complications and neonatal infection, it is recommended to routinely screen all pregnant women for C trachomatis and to screen those at risk for N gonorrhoeae
during the first prenatal visit, with repeat testing during the third
trimester—for chlamydia in patients aged 25 years or less, and for both
chlamydia and gonorrhea in those remaining at increased risk for
Since patients infected with N gonorrhoeae are frequently coinfected with C trachomatis, those treated for gonococcal infection should also receive an agent with activity against chlamydia.1
The recommended treatment regimen for pregnant women with uncomplicated
gonorrhea is a single dose of ceftriaxone 250 mg intramuscularly (IM)
or cefixime 400 mg orally, given in combination with azithromycin 1 g
orally as a single dose (the recommended treatment for chlamydia during
pregnancy). All patients should be tested for eradication of chlamydia 3
weeks after treatment completion.1,5
Genital Herpes: Genital herpes, a viral
infection caused by herpes simplex virus types 1 and 2, afflicts more
than 800,000 pregnant women annually in the United States.6,7
In more than 90% of cases of neonatal herpes (which affects the skin,
eye, mouth, or central nervous system or causes disseminated infection),
the infant acquires the infection during vaginal birth, when it is
exposed to infected secretions in the mother’s genital tract. Therefore,
to prevent neonatal infection, cesarean delivery (CD) is recommended
for women who have active genital lesions or prodromal symptoms
suggestive of genital herpes at the time of labor.7
Additionally, during the third trimester, women without genital herpes
should abstain from intercourse with partners known or suspected to have
genital herpes and to abstain from receptive oral sex with partners
known or suspected to have orolabial herpes.1
The safety of acyclovir, valacyclovir, and famciclovir for herpes
treatment during pregnancy has not been established, and none of these
agents is approved for use during pregnancy.1,8 There is no
increased risk of major birth defects with the use of acyclovir during
pregnancy, and taking acyclovir between the 36th week of pregnancy and
delivery reduces the frequency of disease recurrence and the need for
CD.1,8,9 Therefore, the CDC treatment guidelines for STDs recommend the use of acyclovir over other antivirals during pregnancy.1 TABLE 2 lists common oral dosing regimens for acyclovir. IV acyclovir may be used for severe infections.1
UTIs—whether asymptomatic or symptomatic—are the most common
bacterial infection in pregnancy, occurring in approximately 20% of
patients.10,11 Asymptomatic bacteriuria (ASB) is the presence
of more than 100,000 colony-forming units of bacteria per mL of urine
from two consecutive urine cultures, occurring in the absence of UTI
symptoms.12 Cystitis typically presents with urinary urgency
and/or frequency, dysuria, or hematuria, whereas pyelonephritis usually
involves systemic symptoms such as fever, costovertebral angle
tenderness, flank pain, and nausea and vomiting, in addition to cystitis
Of the 2% to 10% of pregnant women with ASB, 15% to 45% will develop pyelonephritis if it is not treated.11
This is because many physiologic changes occur during pregnancy that
ultimately result in stasis of urine in the ureters or bladder,
increasing the risk of infection.11 It is important to
prevent pyelonephritis in pregnancy, since it may cause maternal or
perinatal complications (i.e., premature delivery, low birthweight, or
fetal death).11,14,15 Therefore, patients should be screened
for bacteriuria via urine culture at least once in early pregnancy
(typically at 12-16 weeks’ gestation or first prenatal visit), with
antibiotic treatment in the event of positive results.12,14 Some experts advocate repeated urine screening in each trimester in order to improve detection of ASB.10,13
The most common microbial etiology of UTI in pregnancy is Escherichia coli.10 Additional pathogens include other gram-negative rods of the Enterobacteriaceae family and group B streptococci (GBS).10,13
Quantitative urine culture is the gold standard for diagnosis of UTI
during pregnancy, but if it is unavailable, local resistance patterns
should be used to select an antibiotic with activity against E coli.10,11
Commonly used antimicrobial regimens for ASB or cystitis include a 3-
to 7-day course of nitrofurantoin and use of a first-generation
cephalosporin, such as cephalexin.10,11,12 A single dose of
fosfomycin may also be considered, although there is limited experience
with the use of this agent during pregnancy.12
Pyelonephritis has historically been managed by initial
hospitalization for IV fluids and IV antibiotics (typically with a
penicillin or cephalosporin active against E coli), followed by a
2-week course of oral antibiotics. An aminoglycoside may be used alone
or in combination with ampicillin for severe cases; however, this agent
is classified as Pregnancy Category C and may cause fetal ototoxicity.
Recent evidence indicates that pregnant women with pyelonephritis who
are at less than 24 weeks’ gestation, are otherwise healthy, are not
having recurrent infections, and do not have fever, nausea, vomiting, or
signs of sepsis may be considered for outpatient therapy. A patient
meeting these criteria may be managed during an observation period in
the emergency department, at which time laboratory values are drawn and
IV hydration and an IM dose of ceftriaxone are administered. The patient
must have a follow-up visit 24 hours later, at which time an additional
dose of ceftriaxone is given and clinical condition is assessed. If the
patient’s clinical condition has improved, she may receive oral
therapy. A commonly used regimen is cephalexin 500 mg four times daily
for 10 days. For patients who remain symptomatic, IM ceftriaxone may be
continued daily for a maximum of 5 days.11,15
After completion of any course of antibiotics for the treatment of
pyelonephritis, a urine culture should be performed to confirm
resolution of bacteriuria. Monthly urine cultures are recommended for
surveillance purposes.11 Because recurrent pyelonephritis
occurs in 6% to 8% of pregnant women, antibiotic prophylaxis with
nitrofurantoin 100 mg orally daily or cephalexin 250 to 500 mg orally
daily is recommended for all patients for the duration of pregnancy
through 4 to 6 weeks postpartum.11,15
GBSD is the primary infectious cause of neonatal morbidity and
mortality in the United States. The main microbial etiology of GBSD is Streptococcus agalactiae, a gram-positive organism that asymptomatically colonizes the vagina or rectum. S agalactiae
occurs in approximately 10% to 30% of pregnant women. Annually, GBS
causes about 1,200 cases of invasive disease (particularly sepsis and
pneumonia), typically within the first 24 to 48 hours of the infant’s
The primary risk factor for infant GBSD is intrapartum GBS
colonization in the mother. The newborn becomes infected through
exposure to GBS, which may ascend into the amniotic fluid. The child may
also be exposed to GBS during passage through the birth canal.16
Two main strategies are recommended to prevent GBSD in newborns:
routine testing of women late in pregnancy and the use of antibiotics
during labor.17 All patients between 35 and 37 weeks’ gestation should be screened for GBS colonization with a vaginal or rectal swab.16
Intrapartum antibiotic prophylaxis is recommended for patients with a
positive screening test and for those who previously delivered an infant
with GBSD or have GBS bacteriuria in the current pregnancy. It also is
advised in patients with unknown GBS colonization status who deliver an
infant at less than 37 weeks’ gestation, have a temperature of at least
100.4°F during labor, or have rupture of membranes for 18 hours or more.
IV PCG at a dosage of 5 million U once, followed by 2.5 to 3 million U
every 4 hours until delivery, is recommended first-line therapy. IV
ampicillin at a dosage of 2 g once, followed by 1 g every 4 hours until
delivery, is considered an acceptable alternative to PCG. Patients with a
history of nonsevere allergy to penicillins may be managed with
cefazolin, whereas those with a severe reaction to penicillins may be
treated with clindamycin or vancomycin, depending upon the infecting
Listeriosis is caused by Listeria monocytogenes, a gram-positive bacterium that is normally found in soil and water.18 This infection occurs primarily in elderly or immunocompromised patients, newborns, and pregnant women.18,19
Pregnant women with listeriosis may be asymptomatic or experience
merely fatigue or muscle aches. The infection can be passed to the fetus
through the placenta or during passage through the birth canal,
potentially causing miscarriage, stillbirth, premature delivery, or
The primary route by which listeriosis occurs is the ingestion of
food contaminated with the bacterium. All pregnant women should be
counseled to eat only fully cooked meats, thoroughly washed vegetables,
or pasteurized milk, and to avoid certain cheeses (see TABLE 3 for more details).19,21
Toxoplasmosis is caused by the parasite Toxoplasma gondii.
Although pregnant women with this infection may be asymptomatic, the
infection can be passed to the fetus through the placenta, potentially
causing congenital disease leading to infant death or to malformation,
mental retardation, deafness, or blindness (either at birth or later in
A pregnant woman may become infected with toxoplasmosis through
foodborne exposure, environmental exposure, or animal transmission.22,24
With foodborne transmission, the primary route of infection is
ingestion of meat containing tissue cysts of the parasite. Since cysts
are immediately killed at 67°C, pregnant women should be counseled to
avoid eating undercooked meat or meat that could be contaminated by
utensils or cutting boards that have been in contact with raw or
contaminated meat.24 Oocyst forms of the parasite may be
present in the environment. A person may also become infected after
accidental ingestion of soil that is contaminated with oocyst forms of
the parasite. Therefore, pregnant women should wear gloves while
gardening, wash their hands after gardening, and wash fruits, herbs, and
vegetables prior to consumption.22,24
Cats play a major role in the transmission of infection to humans.
After a cat eats a rodent or other small animal infected with
toxoplasmosis, the oocyst form of the parasite is shed in its feces for
up to 3 weeks after infection.22 Therefore, a pregnant woman
may become infected with toxoplasmosis by unintentionally touching her
mouth after changing the litter box.23 Patients should be
advised to keep their own cats indoors; feed their cat commercial dry or
canned food rather than raw or undercooked meats; avoid stray cats; and
avoid obtaining a new cat while pregnant. If possible, the patient
should avoid changing cat litter; if this is not possible, she should
wear disposable gloves during the task and wash her hands with soap and
water immediately afterward.23,24 Since the parasite does not
become infectious until 1 to 5 days after it is shed in a cat’s feces,
changing the litter box daily will prevent the spread of infection.23
Infections are common during pregnancy. Pharmacists are in a key
position to improve both maternal and fetal patient outcomes by
counseling the mother on appropriate preventive measures, recommending
optimal antimicrobial therapy regimens, and monitoring for adverse
effects. Pharmacists must actively work with patients and health care
providers to ensure the proper prevention and treatment of infections
1. Workowski KA, Berman S. Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep. 2010;59:1-110.
2. De Santis M, De Luca C, Mappa I, et al. Syphilis infection during pregnancy: fetal risks and clinical management. Infect Dis Obstet Gynecol. 2012;2012:430585.
3. Oswal S, Lyons G. Syphilis in pregnancy. Contin Educ Anaesth Crit Care Pain. 2008;8:224-227.
4. Blatt AJ, Lieberman JM, Hoover DR, Kaufman HW. Chlamydial and gonococcal testing during pregnancy in the United States. Am J Obstet Gynecol. 2012;207:55.e1-e8.
5. Ruhl C. Update on chlamydia and gonorrhea screening during pregnancy. Nurs Womens Health. 2013;17:143-146.
6. CDC. STDs & pregnancy—CDC fact sheet.
Accessed May 1, 2013.
7. Gardella C, Brown ZA. Managing genital herpes infections in pregnancy. Cleve Clin J Med. 2007;74:217-224.
8. Straface G, Selmin A, Zanardo V, et al. Herpes simplex virus infection in pregnancy. Infect Dis Obstet Gynecol. 2012;2012:385697.
9. Sheffield JS, Hollier LM, Hill JB, et al. Acyclovir prophylaxis to
prevent herpes simplex virus recurrence at delivery: a systematic
review. Obstet Gynecol. 2003;102:1396-1403.
10. Schnarr J, Smaill F. Asymptomatic bacteriuria and symptomatic urinary tract infections in pregnancy. Eur J Clin Invest. 2008;38(suppl 2):50-57.
11. Torres M, Moayedi S. Gynecologic and other infections in pregnancy. Emerg Med Clin North Am. 2012;30:869-884.
12. Lumbiganon P, Laopaiboon M, Thinkhamrop J. Screening and treating asymptomatic bacteriuria in pregnancy. Curr Opin Obstet Gynecol. 2010;22:95-99.
13. Le J, Briggs GG, McKeown A, Bustillo G. Urinary tract infections during pregnancy. Ann Pharmacother. 2004;38:1692-1701.
14. Nicolle LE, Bradley S, Colgan R, et al. Infectious Diseases
Society of America guidelines for the diagnosis and treatment of
asymptomatic bacteriuria in adults. Clin Infect Dis. 2005;40:643-654.
15. Jolley JA, Wing DA. Pyelonephritis in pregnancy: an update on treatment options for optimal outcomes. Drugs. 2010;70:1643-1655.
16. Verani JR, McGee L, Schrag SJ. Prevention of perinatal group B streptococcal disease—revised guidelines from CDC, 2010. MMWR Recomm Rep. 2010;59:1-36.
17. CDC. Group B strep (GBS). Prevention in newborns. www.cdc.gov/groupbstrep/about/prevention.html. Accessed May 1, 2013.
18. CDC. Listeria (listeriosis). Definition. www.cdc.gov/listeria/definition.html. Accessed May 1, 2013.
19. CDC. Listeriosis (listeria) and pregnancy. www.cdc.gov/pregnancy/infections-Listeria.html. Accessed May 1, 2013.
20. Bubonja-Sonje M, Mustac E, Brunn A, et al. Listeriosis in pregnancy: case report and retrospective study. J Matern Fetal Neonatal Med. 2013;26:321-323.
21. USDA Food Safety and Inspection Service. Protect your baby and
yourself from listeriosis.
Accessed May 1, 2013.
22. Di Mario S, Basevi V, Gagliotti C, et al. Prenatal education for congenital toxoplasmosis. Cochrane Database Syst Rev. 2013;(2):CD006171.
23. CDC. Parasites—toxoplasmosis (Toxoplasma infection). Pregnant women. www.cdc.gov/parasites/toxoplasmosis/gen_info/pregnant.html. Accessed May 1, 2013.
24. Robert-Gangneux F, Dardé ML. Epidemiology of and diagnostic strategies for toxoplasmosis. Clin Microbiol Rev. 2012;25:264-296.
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