You are in: eMedicine Specialties > Infectious Diseases > MEDICAL TOPICS Bacterial Infections and PregnancyArticle Last Updated: Nov 29, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Heather Comer Yun, MD, Consulting Staff, Infectious Disease Service, Brooke Army Medical Center, Fort Sam Houston Heather Comer Yun is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, Armed Forces Infectious Diseases Society, and Infectious Diseases Society of America Coauthor(s): Haizal Hamza, MD, Staff Physician, Department of Internal Medicine, Fairview Ridges Clinic; Leonard B Berkowitz, MD, Chief, Divisions of Infectious Diseases and HIV/AIDS Services, Brooklyn Hospital Center; Clinical Assistant Professor, Department of Medicine, State University of New York at Brooklyn; Fauzia Khattak, MD, Staff Physician, Department of Internal Medicine, Brooklyn Hospital Center/Cornell University Editors: Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Carl V Smith, MD, The Distinguished Chris J and Marie A Olson Chair of Obstetrics and Gynecology, Professor, Department of Obstetrics and Gynecology, University of Nebraska Medical Center; Frederick B Gaupp, MD, Consulting Staff, Department of Family Practice, Assumption Community Hospital; Carl V Smith, MD, The Distinguished Chris J and Marie A Olson Chair of Obstetrics and Gynecology, Professor, Department of Obstetrics and Gynecology, University of Nebraska Medical Center Author and Editor Disclosure Synonyms and related keywords: bacterial infections and pregnancy, group B Streptococcus, group B streptococci, GBS, GBS infection, Streptococcus agalactiae, S agalactiae, Chlamydia trachomatis, C trachomatis, Neisseria gonorrhoeae, N gonorrhoeae, Escherichia coli, E coli, Staphylococcus saprophyticus, S saprophyticus, Proteus mirabilis, P mirabilis, Listeria monocytogenes, L monocytogenes, Treponema pallidum, T pallidum, Klebsiella species, Enterobacter species, Enterococcus species, urinary tract infection, UTI, pelvic inflammatory disease, PID, bacteriuria, cystitis, pyelonephritis, listeriosis, syphilis, chlamydia, gonorrhea, gonococcus, bacterial vaginosis INTRODUCTIONSection 2 of 11
  This article focuses on common bacterial infections in pregnancy and describes the manifestations of these infections and the therapies used to treat them. GROUP B STREPTOCOCCUSSection 3 of 11
Group B Streptococcus (GBS) is the most common cause of life-threatening infections in newborns; thus, GBS is the primary focus of any discussion about infections and pregnancy. Infections caused by GBS affect both mother and child. Since the emergence of this pathogen in the 1970s, the increased use of intrapartum prophylaxis has decreased the infection rate by 70%. Etiology Streptococcus agalactiae, or GBS, is a facultative, beta-hemolytic, fastidious, gram-positive coccus. GBS can be found as part of normal vaginal, rectal, and oral flora. The virulence of the organism depends largely on the polysaccharide capsule. Transmission Twenty to 25% of pregnant women are asymptomatic carriers of vaginal or rectal GBS. Intrapartum transmission occurs via ascending spread from this colonization. Clinical spectrum Because only 0.5-1% of mothers who carry GBS develop signs and symptoms of disease, clinical diagnosis of GBS infection can be problematic. In pregnant women, GBS is a cause of cystitis, amnionitis, endometritis, and stillbirth. Occasionally, GBS has caused endocarditis and meningitis in pregnant women, while, in postpartum women, GBS has been identified as a cause of urinary tract infections (UTIs) and pelvic abscesses. In newborns, GBS infection can manifest as 2 different diseases, depending on the interval between delivery and symptom onset. Respiratory distress, apnea, and shock are the most common early-onset manifestations. Nonfocal bacteremia and meningitis are the most common late-onset manifestations. Babies who survive the initial insult face possible hearing or vision loss, learning disabilities, and other neurological sequelae. Screening recommendation from the US Centers for Disease Control and Prevention The US Centers for Disease Control and Prevention (CDC) recommends that all pregnant women at 35-37 weeks’ gestation undergo screening with a vaginal and rectal swab for culture.1 If the culture result is positive, the woman should be treated during labor. Patients who have GBS bacteriuria during the current pregnancy or who have delivered a previous infant with invasive GBS disease do not require culture and should receive intrapartum antibiotics. If culture results are unknown at the time of delivery, a risk-based approach can be used to determine whether the mother should receive antibiotics. In this approach, high-risk patients are treated after identification using the following criteria:
However, women with negative screening culture results within 5 weeks of delivery do not require treatment, even if these obstetric risk factors (premature delivery, prolonged rupture of membranes, intrapartum fever) develop. Treatment During labor, 5 million U of penicillin G should be given as an intravenous loading dose, followed by 2.5 million U every 4 hours until delivery. An alternative therapy is 2 g of ampicillin as an intravenous loading dose, followed by 1 g every 4 hours until delivery. In patients who are allergic to penicillin and at low risk for anaphylaxis, consider 2 g of cefazolin as an intravenous loading dose, followed by 1 g every 8 hours until delivery. Patients who are allergic to penicillin at high risk for anaphylaxis may be given 900 mg of intravenous clindamycin every 8 hours or 500 mg of intravenous erythromycin every 6 hours until delivery. Patients with a history of an anaphylactic reaction to penicillin should undergo testing for resistance before antibiotics are selected. If susceptibility to clindamycin or erythromycin has not been established, 1 g of intravenous vancomycin every twelve hours can be used until delivery. Neonates delivered from a mother who received prophylaxis must be careful observed for signs and symptoms of disease. URINARY TRACT INFECTIONSSection 4 of 11
Urinary tract infections (UTIs) are a common problem in women at all stages of life; this is particularly true of pregnant women. Women are anatomically predisposed to UTIs because of their shorter urethra and the proximity of the urethra to the anus and vagina. UTIs are an especially important topic in pregnancy, as even asymptomatic bacteriuria can lead to complications such as pyelonephritis and premature labor. The most common causative organisms include the following:
Clinical spectrum Symptomatic infection and asymptomatic infection are both of clinical importance in pregnant women, unlike in healthy nonpregnant women. Infection can involve the lower or upper urinary tracts and can cause asymptomatic bacteriuria, cystitis, or pyelonephritis. Asymptomatic bacteriuria, which develops in 10-15% of pregnant women, is not more common in pregnant women than in nonpregnant women; however, it is more likely to lead to acute pyelonephritis in pregnant women. Approximately 25-30% of pregnant women with untreated bacteriuria develop pyelonephritis, compared with 1-4% of pregnant women without bacteriuria. Complications of bacteriuria in pregnancy include maternal anemia, low neonatal birth weight, hypertension, and prematurity. Cystitis is not more common in pregnant women than in nonpregnant women. The symptoms of cystitis are often confused with symptoms noted in normal pregnancy and include urgency, frequency, suprapubic discomfort, and dysuria without fever or costovertebral angle tenderness. Urine culture findings are positive, and urinalysis reveals occasional hematuria or pyuria. The effects of cystitis in pregnancy, beyond the discomfort for the woman, are unknown but likely include some of the same complications as those of asymptomatic bacteriuria. Acute pyelonephritis is more common in pregnant women than in nonpregnant women and is probably due to stasis of urine and bacteria in the urinary tract caused by relative obstruction. This is due to dilatation of the ureters secondary to progesterone in early pregnancy and to the mechanical obstruction from the gravid uterus later in pregnancy. Second only to obstetric complications, acute pyelonephritis is the most common indication for hospitalization in pregnant patients. Although symptoms may be protean, acute pyelonephritis is typically characterized by fever, costovertebral angle tenderness, urinalysis findings with white blood cells and bacteria, and significant bacteriuria. The severity of pyelonephritis may range from minimal symptomatology to frank urosepsis. Fetal outcomes include low birth weight and prematurity. Screening and diagnosis Because asymptomatic bacteriuria is clinically significant in pregnancy, it should be aggressively sought, diagnosed, and treated in all stages. The Infectious Diseases Society of America (IDSA) recommends that all pregnant women should undergo screening with urine culture at least once during early pregnancy. Significant bacteriuria is defined as more than 100,000 colony-forming units (CFU) of a single organism in a clean-catch specimen. Treatment Any overt UTI or asymptomatic bacteriuria in pregnancy must be treated to prevent complications mentioned above. Sulfonamides, amoxicillin, amoxicillin-clavulanate, cephalexin, and nitrofurantoin are all acceptable antibiotics. However, avoidance of sulfonamides in the last few weeks of gestation is recommended to prevent kernicterus and hyperbilirubinemia in the newborn. Trimethoprim is relatively contraindicated during the first trimester because of theoretical teratogenicity involving its antifolate activity. Nitrofurantoin may cause hemolysis in patients or fetuses with glucose-6-phosphate dehydrogenase (G6PD) deficiency. The duration of therapy required to treat asymptomatic bacteriuria has not been determined; in a recent Cochrane review, insufficient evidence was found to recommend a specific length of therapy.2 A 7-day regimen eradicates bacteriuria in 70-80% of patients and is recommended to treat acute cystitis. Single-dose therapy for asymptomatic bacteriuria is less effective. Recurrent UTIs may warrant postcoital prophylaxis with a single dose of cephalexin or nitrofurantoin macrocrystals. Cystitis can generally be treated in the same manner as is asymptomatic bacteriuria, with the caveat that single-dose regimens are even less likely to be effective. Because these patients are symptomatic, treatment can be started before the results are confirmed with urine culture. Women treated for cystitis should be monitored with monthly urine cultures, as approximately 20% of women who have cystitis develop another UTI during the course of their pregnancy. Apart from the need to avoid certain antibiotics, treatment of pyelonephritis in pregnant women mirrors that in nonpregnant patients. Although mild cases may be treated in an outpatient setting, many require hospitalization and intravenous antibiotics in addition to parenteral hydration for nausea, vomiting, and dehydration. Initial antibiotic therapy may be empiric, followed by tailoring to the pathogen grown in the urine. Most patients with cystitis show symptomatic improvement within 1-2 days of beginning therapy; pyelonephritis can take 2-3 days to improve, even with effective therapy. If no improvement is observed, consider resistant organisms, nephrolithiasis, abscess formation, and obstruction as causes of therapy failure. Women who have experienced an episode of acute pyelonephritis should be monitored frequently with repeat urine cultures. If close follow-up care is not practical, continuous suppressive therapy can be considered. LISTERIOSISSection 5 of 11
Listeriosis is an uncommon, but perhaps underdiagnosed, cause of neonatal sepsis. Approximately 2500 cases are reported annually in the Etiology Listeria monocytogenes is a gram-positive, motile bacillus with aerobic and facultative anaerobic characteristics. The organism is found in soil and water and can be carried by animals that do not appear ill, leading to contamination of food of animal origin, such as meats and dairy products. Unpasteurized raw milks or foods are also sources of Listeria organisms. Transmission Pregnant women are 20 times more likely than nonpregnant women to contract listeriosis, and approximately one third of all reported cases of listeriosis occur during pregnancy, typically during the third trimester. Infection has mainly occurred after ingestion of contaminated food, although rare cases of local disease following direct contact with infected animals and nosocomial transmission have been reported. The organism is found in soil and water. Vegetables become contaminated from the use of manure fertilizer, while animals may be asymptomatic carriers transmitting disease to individuals who eat their infected meat. Outbreaks of listeriosis are still reported. Contaminated turkey meat caused a multistate outbreak in 2002 and led to 46 cases with 7 deaths and 2 stillbirths.3 Clinical spectrum The most common clinical presentation in pregnant patients with listeriosis is bacteremia. For unknown reasons, CNS infections, which are common in other populations at risk for listeriosis, are rare in pregnant women with listeriosis. Pregnant patients with listeriosis are often asymptomatic. Symptomatic pregnant patients often have a febrile illness similar to influenza with fever, muscle aches, and, occasionally, nausea or diarrhea during the bacteremic phase of the disease. Although the symptoms may be mild, listeriosis can still lead to premature delivery, infection of the newborn, or even stillbirth. Placental transfer of the organism to the fetus can cause amnionitis, which usually results in either spontaneous septic abortion or premature labor with delivery of an infected baby. Fetal infection may manifest as septicemia, meningoencephalitis, or disseminated granulomatous lesions with microabscesses. Twenty-two percent of perinatal infections result in neonatal death or stillbirth.4 In neonates, the mortality rate is approximately 50%. Mortality is more likely in early-onset neonatal sepsis. Late-onset listeriosis typically manifests as meningitis at 2-4 weeks of life. Screening Routine screening for Listeria is not currently recommended in pregnant women because carriage of these organisms in the vagina or gut is not thought to be associated with a predisposition for listeriosis in pregnancy. Blood cultures are the primary means of diagnosis, and results are more likely to be positive when the patient is febrile. In the neonate, Listeria can be cultured from meconium, nose or eye swabs, urine, cerebrospinal fluid, blood, placental tissue, or lochia. CDC recommendations Prevention is mainly achieved by educating pregnant women to avoid unsafe foods. The following are recommendations by the CDC for the general population:
The following are additional recommendations for high-risk patients (including pregnant patients):
Diagnosis Confirming a diagnosis of listeriosis requires a culture positive for L monocytogenes from an otherwise sterile site (eg, blood, CSF). Serological testing is not reliable for confirming a diagnosis, and stool cultures are not sensitive or specific. Treatment Ampicillin is the drug of choice for treating listeriosis; a 2-week intravenous course is required for bacteremia. Trimethoprim/sulfamethoxazole is the usual alternative for patients allergic to penicillin but, as described above, can be problematic during the first or third trimesters. SYPHILISSection 6 of 11
Early diagnosis and treatment are extremely important in preventing the potential effects of syphilis in pregnant women and their infants. Untreated primary or secondary syphilis in pregnant women leads to congenital syphilis in 40-50% of cases. In 2002, 451 cases of congenital syphilis were reported in the Lack of prenatal care and failure to properly diagnose and treat syphilis in the mother are the most important factors that lead to congenital syphilis should be the focus of preventive efforts. Etiology Syphilis is caused by Treponema pallidum, a helical, tightly coiled, motile spirochete. Clinical spectrum The stage of maternal disease during which the fetus is exposed to infection determines the morbidity risk; the earlier the stage of disease, the higher the risk of morbidity. Untreated primary or secondary syphilis in pregnancy leads to a fetal infection rate of almost 100%. The disease can cause stillbirth, neonatal death, or congenital syphilis. The clinical presentations of syphilis in pregnant women mirror those in nonpregnant women. In primary syphilis, a hard, painless red ulcer typically forms on the vulva, cervix, or vagina. Secondary syphilis predominantly manifests as a nonpruritic rash that may involve the palms and soles. Fever, lymphadenopathy, and joint pain are less common manifestations of secondary syphilis. The latent stage causes no symptoms, and, although the disease may not be transmitted to sexual partners, it is still transmissible to the fetus. One third of patients may eventually develop tertiary syphilis, which can result in cardiovascular or gummatous disease. Neurosyphilis can occur at any stage, resulting in CNS or ophthalmic presentations. Screening Even when syphilis is considered unlikely, routine antenatal screening is warranted for prevention and surveillance. The earlier in pregnancy the treatment is provided, the more efficacious it is. Therefore, serologic tests should be performed at the initial prenatal visit. If the patient is considered to be at high risk, tests should be repeated at 28 weeks' gestation and at delivery. Diagnosis The nontreponemal antibody tests are generally used for screening. These tests, including rapid plasmin reagin and Venereal Disease Research Laboratory (VDRL) tests, are highly sensitive but nonspecific. Nontreponemal antibody test results are often false-positive in pregnant women; therefore, positive findings should be confirmed with specific antitreponemal antibody tests such as the microhemagglutination assay–T pallidum (MHA-TP) and the fluorescent treponemal antibody absorption test (FTA-ABS). Antitreponemal antibody test findings are not indicators of current infection because results may remain positive for life. In primary syphilis, the diagnosis can be confirmed by identifying T pallidum in dark-field examination of material taken from a lesion. Because most pregnant women do not have visible lesions, serologic screening is the primary means of establishing the diagnosis. Treatment Once syphilis is diagnosed, consider other sexually transmitted diseases, especially HIV, while starting treatment. Treatment in pregnant women is the same as in nonpregnant women, with a single dose of 2.4 million U of intramuscular benzathine penicillin for primary, secondary, and early latent syphilis, but some experts recommend a second dose of benzathine penicillin G 1 week after the initial dose, especially in the third trimester or in patients with secondary syphilis. In late latent syphilis, treatment consists of 3 doses of benzathine penicillin (as in nonpregnant women), each one week apart. If results of subsequent quantitative VDRL or an equivalent test show a 4-fold increase, re-treat the patient and perform a lumbar puncture to rule out neurosyphilis. Penicillin is the only drug that can be used in pregnant women with syphilis. Women who are allergic to penicillin must be desensitized and then treated with penicillin. Erythromycin may not prevent congenital syphilis, and the tetracyclines are not recommended in pregnant women. Ceftriaxone and azithromycin have not been adequately studied in this context. Using penicillin therapy in pregnant women with early syphilis can cause a Jarisch-Herxheimer reaction. In addition to the usual manifestations, pregnant women can present with uterine contractions, preterm labor, and premature delivery. However, these concerns should not delay necessary therapy. For excellent patient education resources, visit eMedicine's Sexually Transmitted Diseases Center. Also, see eMedicine's patient education article Syphilis. CHLAMYDIASection 7 of 11
Chlamydia trachomatis infection is the most common bacterial sexually transmitted disease in the Etiology C trachomatis is a bacterium with a unique biphasic life cycle. The elementary body is an extracellular form that is necessary for transmission. Upon uptake into a host cell, differentiation into the reticulate body occurs, which is the replicative form. After binary fission occurs, daughter reticulate bodies transform into elementary bodies, which are then released from the cell. Transmission The usual mode of transmission to the fetus is vertical during the second stage of labor. The major routes of entry are the eye and the nasopharynx. Clinical spectrum Approximately 75% of women with C trachomatis infection are asymptomatic. The disease can cause endometritis, cervicitis, acute PID, and acute urethral syndrome in all women and chorioamnionitis, postpartum endometritis, and gestational bleeding in pregnant women. The endometritis noted in these women can be observed after delivery, and infection may be severe enough to necessitate hysterectomy. In neonates, C trachomatis infection commonly causes conjunctivitis (ophthalmia neonatorum) and pneumonia. The contention that chlamydia may induce premature labor is controversial. If a woman has symptoms of dysuria and frequency and urine culture results are negative, chlamydia is frequently the cause. Screening The CDC recommends that all pregnant women undergo screening early in pregnancy and that pregnant woman younger than 25 years and high-risk patients undergo screening again in the third trimester. Screening early in pregnancy increases the opportunity to improve the pregnancy outcome, whereas screening in the third trimester prevents transmission to the infant. Screening methods are delineated below. Diagnosis Chlamydial cervicitis should be considered in the presence of a yellow or green vaginal discharge, greater than 10 polymorphonuclear leukocytes per high-power field, and bleeding or edema of the cervix. However, physical examination findings are completely normal in many infected women. According to the CDC, the following are the accepted screening methods:5
Treatment Tetracyclines and fluoroquinolones are contraindicated in pregnant women. However, azithromycin (1 g orally as a single dose) is considered to be safe and effective for treating urogenital chlamydial infections in pregnancy and is now the first-line recommended therapy. Amoxicillin 500 mg orally 3 times per day for 7 days is an alternative. Erythromycin is a second-line agent because of compliance-limiting gastrointestinal adverse effects. Retest treated women after 3-4 weeks and evaluate and treat sexual contacts. GONORRHEASection 8 of 11
Gonococcal infections cause no symptoms in approximately 50% of patients and thus warrant screening in pregnancy. Gonococcal infections are second only to chlamydial infections in the number of cases of bacterial STDs reported to the CDC. A pregnant woman with gonorrhea can transmit the infection to her infant at the time of delivery, causing life-threatening infections. Early detection and treatment lowers the likelihood of these complications. Etiology Gonorrhea is caused by Neisseria gonorrhoeae, a gram-negative diplococcus. Transmission Gonorrhea is transmitted vertically during the birth process. No evidence suggests placental transmission. Clinical spectrum Gonorrhea can infect the uterus, cervix, and fallopian tubes, leading to ectopic pregnancy and infertility. During pregnancy, women with gonorrhea may be asymptomatic, although some reports have described manifestations of endocervicitis, premature rupture of membranes, chorioamnionitis, septic abortion, intrauterine growth retardation, prematurity, and postpartum sepsis. However, the frequency of PID is reduced because upward passage of bacteria during pregnancy is prevented. Proctitis develops in up to 50% of women with gonorrhea and may be the only site colonized, necessitating rectal specimens for diagnosis if this is suspected. Patients with gonococcal pharyngitis are frequently asymptomatic, and the pharynx may be the only site colonized. Newborns exposed to gonorrhea during vaginal delivery can develop an acute conjunctivitis known as ophthalmia neonatorum, sepsis, arthritis, and/or meningitis. Pregnancy is a predisposing factor to the development of disseminated gonococcal infection. The classic presentation of disseminated disease is the triad of arthritis, skin lesions, and fever. The rash is vesicular and pustular, usually over the distal joints. The presenting symptom is often migratory polyarthralgia. Screening Because pregnant women with gonorrhea are often asymptomatic, screening is imperative for preventing complications. The Diagnosis A culture specimen should be taken directly from the endocervix onto Thayer-Martin media. Other sites, such as the pharynx, rectum, and urethra, should also be cultured as indicated. A Gram stain of the endocervical secretions should be performed when an immediate diagnosis is necessary. Gram-negative diplococci in polymorphonuclear leukocytes are diagnostic. Enzyme immunoassay is another rapid means of diagnosis. Treatment The treatment of choice for uncomplicated cervicitis is 125 mg of intramuscular ceftriaxone a single dose. Pregnant women who are allergic to penicillin can be treated with spectinomycin. Fluoroquinolones are contraindicated during pregnancy and are no longer recommended to treat gonorrhea because of resistance.6 Historically, all patients diagnosed with gonococcal infection have been recommended to also receive empiric therapy for C trachomatis. This recommendation still applies if chlamydial testing was not performed or if a test other than NAAT was used to test for chlamydial infection. However, the NAAT tests are sensitive enough for C trachomatis that patients with a NAAT test negative for C trachomatis at the time of gonococcal testing do not require empiric therapy for chlamydial infection. BACTERIAL VAGINOSISSection 9 of 11
Bacterial vaginosis is a clinical syndrome caused by excessive growth of bacteria that may normally be present in the vagina. The vagina is normally colonized with gram-positive, gram-negative, aerobic, and anaerobic bacteria. The dominant commensal found in the vagina is Lactobacillus, and the constitution of vaginal flora is altered by local pH changes. In the Etiology The organisms responsible for causing bacterial vaginosis depend mainly on the pH of the vagina. With a pH of more than 4.5, Gardnerella vaginalis and anaerobes become the prominent associated organisms. The etiology is polymicrobial in nature and is associated with G vaginalis, Bacteroides species, Mobiluncus species, Peptococcus species, Ureaplasma urealyticum, and Mycoplasma hominis. Clinical spectrum Women with bacterial vaginosis may be asymptomatic or may report an abnormal vaginal discharge with an unpleasant, fishlike odor, especially after sexual intercourse. The discharge is generally white or gray, and women may experience burning during urination or itching around the vagina. The bacteria can ascend and colonize the amniotic membranes, decreasing the tensile strength of the membranes and causing the weakened membranes to rupture. G vaginalis infection can also cause prostaglandin production and can lead to premature labor unresponsive to tocolytic therapy. In one study, 43% of pregnant patients with bacterial vaginosis went on to have a preterm labor. Diagnosis A diagnosis of bacterial vaginosis can be confirmed via clinical or Gram stain criteria. When using the clinical criteria, 3 of the following 4 conditions should be present:
When using Gram stain for diagnosis, determine the relative concentration of the bacterial morphotypes characteristic of the altered flora of bacterial vaginosis. Screening The United States Preventive Services Task Force has determined that evidence is insufficient to warrant routine screening for bacterial vaginosis in pregnancy. The CDC suggests that women at high risk for premature labor (eg, women who have previously delivered a premature infant) should undergo screening at the first prenatal visit. Treatment Treatment is the same as in nonpregnant patients, except that clindamycin cream should be avoided during the second half of pregnancy because it can increase the risk of premature birth and other adverse outcomes. Metronidazole at 250-500 mg orally twice per day for 7 days or clindamycin 300 mg orally twice per day for 7 days are recommended. ANTIBIOTICS IN PREGNANCYSection 10 of 11
Cautious use of antibiotics is especially important during pregnancy because they can affect both the mother and the fetus. Without exception, antimicrobials cross the placenta; thus, the fetus is exposed to the adverse effects of every antibiotic taken by the mother. Although prescription drugs account for less than 1% of all congenital malformations, potential teratogenic effects must be considered since antimicrobials are so commonly prescribed. Classification Very few data regarding the teratogenic potential of most antibiotics in humans are available. The US Food and Drug Administration has categorized all antibiotics according to the risks associated with their use in pregnancy. These categories are as follows:
In all classes of drugs, the benefits of antibiotic use must always outweigh the risks. Commonly used antibiotics
REFERENCESSection 11 of 11
Bacterial Infections and Pregnancy excerpt Article Last Updated: Nov 29, 2007 |
