Metronidazole treatment in pregnancy

Investigating the efficacy and safety of metronidazole during pregnancy; A systematic review and meta-analysis

OBJECTIVE

We aimed to review and analyze studies focusing on the efficacy of metronidazole in reducing the risk of preterm birth and the safety of metronidazole taking into account the different doses, duration of treatment and routes of administration.

STUDY DESIGNS

Embase, Cochrane Library and PubMed were searched up to 29 July 2019 to identify studies assessing metronidazole exposure during pregnancy. Additional studies were identified from reference lists of retrieved papers. Measured outcomes were preterm births (<37 weeks of gestation) and associated delivery outcomes such as spontaneous abortions (≤ 20 weeks of gestation), stillbirths (≥20 weeks of gestation) and low birth weight (<2500 g) irrespective of the period of exposure and major malformations after first-trimester exposure. Overall effect estimates for RCTs and observational studies were calculated using the random-effects model and pooled using Risk Ratios (RR) and Odds Ratios (OR) respectively. ROB-2 and ROBINS-I tool were used to assess Risk of Bias for RCTs and observational studies, respectively.

RESULTS

Twenty-four studies (17 observational studies and 7 RCTs) were selected. Pooled RR was 1.10 (95 % CI 0.78-1.55; n = 7; I2 = 72 %) for preterm birth. Subgroup analysis found RR 1.67; 95 % CI 1.07-2.62; n = 3; I² = 32 %) for treatment duration of ≤3 days among women with a previous preterm delivery. Pooled OR for spontaneous abortion was 1.72 (95 % CI 1.40-2.12; n = 5; I2 = 72 %) and 1.15 (95 % CI 0.98-1.34; n = 12; I2 = 25 %) for major malformations. After exclusion of studies with critical risk of bias, pooled OR were 1.7 (1.42-2.04; n = 3; I2 = 19 %) and 1.13 (0.93-1.36; n = 9; I2 = 28 %) respectively. Among several specific malformations analyzed, only congenital hydrocephaly was significantly increased at 4.06 (95 % CI 1.75-9.42; n = 2; I² = 0%).

CONCLUSIONS

Data do not confirm the efficacy of metronidazole in reducing the risk of preterm birth and associated delivery outcomes. Further research is required to confirm the effect of high dose and short duration of metronidazole treatment on preterm birth among the high-risk group. Regarding the increased odds of spontaneous abortion, RCTs are required to assess the role of the underlying infection. The need for further studies to confirm the risk of congenital hydrocephaly is paramount.

Trichomoniasis: Challenges to Appropriate Management

Trichomonas vaginalis infection is a common cause of vaginal irritation in women and is the most common nonviral sexually transmitted disease in the world. It has been associated with serious sequelae, the most notable of which are prematurity, low birth weight, and increases in human immunodeficiency virus transmission. We review advances in diagnosis and treatment and the current controversies regarding management.

Micronucleus induction by metronidazole in rat vaginal mucosa

Metronidazole (MTZ) is used for the treatment of many infectious diseases, including vaginal infections. While data indicate that MTZ is mutagenic and induces micronuclei in rodents, there is no information on the genotoxicity of MTZ in epithelial vaginal cells or cervical cells. In the present study, we have instilled MTZ into the vagina of rats and evaluated the micronucleus (MN) frequency in proestrus rat vaginal mucosal cells. The first identified proestrus before treatment was used to establish basal proestrus micronucleated cell (PMNC) frequencies. Rats then were assigned to one of five groups: a negative control, three MTZ treatment groups (30, 50, or 100 mg/kg MTZ), and a positive control treated with 2.5 mg of 5-fluorouracil (5-Fu) per rat. Following treatment for five consecutive days, vaginal cell samples were taken daily until three cycles of estrus were completed. Smears prepared from the samples were evaluated for micronuclei in proestrus cells. No differences were found between the PMNC frequencies of the negative control and the 30 and 50 mg/kg MTZ groups. The group treated with 100 mg/kg MTZ, however, had significantly elevated PMNC frequencies in the first and second proestrus samples, while 5-Fu treatment produced significant increases in PMNC frequency in the second and third proestrus. These results indicate that topical administration of relatively high concentrations of MTZ is genotoxic in rat vaginal mucosa cells.

Trichomoniasis and its treatment

Trichomonas vaginalis has long been recognized as a cause of infectious vaginitis in women. More recently, studies have demonstrated a significant burden of disease in men with urethritis or men at high risk for sexually transmitted diseases. There is increasing interest in this pathogen as more data accumulates linking it to HIV transmission and perinatal morbidity. New diagnostic methods have emerged that may increase sensitivity of diagnosis or improve point-of-care access to testing. Nitroimidazoles remain the mainstay of therapy. Metronidazole and tinidazole are highly effective as single-dose therapy. Unfortunately, despite the link between T. vaginalis infection and perinatal morbidity, nitroimidazole therapy during pregnancy remains controversial. Although metronidazole resistance is currently uncommon, pharmacological features and nitroimidazole resistance patterns suggest that tinidazole may be more effective in treating patients with metronidazole treatment failure. Alternatives to nitroimidazole therapy are few, and most have limited efficacy and significant toxicity.

Recent pharmacological advances in the treatment of preterm membrane rupture, labour and delivery

Preterm delivery (before 37 completed weeks of gestation) is the major determinant of infant mortality. In women with a previous preterm birth associated with bacterial vaginosis, prophylactic antibiotics (e.g., metronidazole) reduce the risk of preterm birth and low birth weight. Trichomonas vaginalis increases the risk of preterm delivery, but metronidazole is not beneficial for this and may even be detrimental. Antibiotic use (e.g., erythromycin) prolongs pregnancy in late premature rupture and has health benefits for the neonate. However, antibiotics are probably not useful in preterm labour. Intramuscular 17alpha-progesterone and vaginal progesterone reduce the rate of preterm labour in high-risk pregnancies, including previous spontaneous preterm delivery. Magnesium sulfate, beta2-adrenoceptor agonists and the oxytocin-receptor antagonist, atosiban, are effective in reducing uterine contractions short-term, but there is little evidence that this leads to improved outcomes for the neonate. However, tocolysis with calcium-channel blockers does seem to lead to better outcomes for the neonate. Fetal side effects, such as ductus arteriosus constriction and impaired renal function, are associated with the inhibition of prostaglandin synthesis with indomethacin. New approaches and more effective drugs are required in the treatment of preterm delivery.

Treatment of community-acquired lower respiratory tract infections during pregnancy

The incidence of lower respiratory tract infection (LRTI) in women of child-bearing age is approximately 64 per 1000 population. The spectrum of illness ranges from acute bronchitis, which is very common, through influenza virus infection and exacerbations of underlying lung disease, to pneumonia, which, fortunately is uncommon (<1.5% LRTI), but can be severe.

Acute bronchitis is generally mild, self-limiting and usually does not require antibacterial therapy. Influenza virus infection in pregnant women has been recently related to increased hospitalization for acute cardiorespiratory conditions. At present, the safety of the newer neuraminidase inhibitors for the treatment of influenza virus infection has not been established in pregnancy and they are not routinely recommended. In influenza virus infection complicated by pneumonia, antibacterial agents active against Staphylococcus aureus and Streptococcus pneumoniae superinfection should be used.

There are few data on infective complications of asthma or COPD in pregnancy. The latter is rare, as patients with COPD are usually male and aged over 45 years. Management is the same as for nonpregnant patients.

The incidence and mortality of pneumonia in pregnancy is similar to that in nonpregnant patients. Infants born to pregnant patients with pneumonia have been found to be born earlier and weigh less than controls. Risk factors for the development of pneumonia include anemia, asthma and use of antepartum corticosteroids and tocolytic agents. Based on the few available studies, the main pathogens causing pneumonia are S. pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae and viruses. β-Lactam and macrolide antibiotics therefore remain the antibiotics of choice in terms of both pathogen coverage and safety in pregnancy. In HIV-infected pregnant patients, recurrent bacterial pneumonia, but not Pneumocystis carinii pneumonia (PCP), is more common than in nonpregnant patients. Trimethoprim/sulfamethoxazole (cotrimoxazole) has not definitely been associated with adverse clinical outcomes despite theoretical risks. Currently it is still the treatment of choice in PCP, where mortality remains high.

In conclusion, there are few data specifically related to pregnant women with different types of LRTI. Where data are available, no significant differences compared with nonpregnant patients have been identified. In considering the use of any therapeutic agent or investigation in pregnant patients with LRTI, safety aspects must be carefully weighed against potential benefit. Otherwise, management strategies should not differ from those for nonpregnant patients. Further research in this area is warranted.

Treatment of sexually transmitted diseases in women

Guidelines for the treatment of patients with sexually transmitted infection are developed by the Centers for Disease Control and Prevention after consultation with a group of professionals knowledgeable in the field. This article briefly introduces various infections, reviews new diagnostic information, and presents the latest guidelines for therapy. All recommended and alternative regimens are drawn from the most recent treatment guidelines. Although this article focuses primarily on therapy, it also emphasizes the importance of counseling and prevention. Clinicians have the opportunity and obligation to provide education and counseling to patients. Prevention messages should be tailored to the individual patient with consideration given to her specific risk behaviors.

Trichomoniasis: under control or undercontrolled?

Aside from human papillomavirus, trichomoniasis is the most common sexually transmitted infection in the United States today, yet it has long been regarded as a sexually transmitted infection of minor importance. Medical opinion has traditionally held that it plays little role in health complications in women, and it is rarely seen in men. However, evidence has recently accumulated implicating Trichomonas vaginalis as a contributor to a variety of adverse outcomes among both sexes. Among both women and men, the association of T vaginalis with human immunodeficiency acquisition and transmission has been shown in multiple studies. Among women, trichomoniasis may play a role in development of cervical neoplasia, postoperative infections, and adverse pregnancy outcomes and as a factor in atypical pelvic inflammatory disease and infertility. Among men, trichomoniasis has emerged as a cause of nongonoccocal urethritis and as contributing to male factor infertility. As evidence continues to accumulate, the time has come to increase diagnostic efforts beyond traditional sexually transmitted disease clinic settings.

Failure of metronidazole to prevent preterm delivery among pregnant women with asymptomatic Trichomonas vaginalis infection

BACKGROUND

Infection with Trichomonas vaginalis during pregnancy has been associated with preterm delivery. It is uncertain whether treatment of asymptomatic trichomoniasis in pregnant women reduces the occurrence of preterm delivery.

METHODS

We screened pregnant women for trichomoniasis by culture of vaginal secretions. We randomly assigned 617 women with asymptomatic trichomoniasis who were 16 to 23 weeks pregnant to receive two 2-g doses of metronidazole (320 women) or placebo (297 women) 48 hours apart. We treated women again with the same two-dose regimen at 24 to 29 weeks of gestation. The primary outcome was delivery before 37 weeks of gestation.

RESULTS

Between randomization and follow-up, trichomoniasis resolved in 249 of 269 women for whom follow-up cultures were available in the metronidazole group (92.6 percent) and 92 of 260 women with follow-up cultures in the placebo group (35.4 percent). Data on the time and characteristics of delivery were available for 315 women in the metronidazole group and 289 women in the placebo group. Delivery occurred before 37 weeks of gestation in 60 women in the metronidazole group (19.0 percent) and 31 women in the placebo group (10.7 percent) (relative risk, 1.8; 95 percent confidence interval, 1.2 to 2.7; P=0.004). The difference was attributable primarily to an increase in preterm delivery resulting from spontaneous preterm labor (10.2 percent vs. 3.5 percent; relative risk, 3.0; 95 percent confidence interval, 1.5 to 5.9).

CONCLUSIONS

Treatment of pregnant women with asymptomatic trichomoniasis does not prevent preterm delivery. Routine screening and treatment of asymptomatic pregnant women for this condition cannot be recommended.

Pregnancy outcome after gestational exposure to metronidazole: a prospective controlled cohort study

BACKGROUND

Metronidazole is an important antibacterial agent commonly used in women of reproductive age. Its use in pregnancy is a reason for concern for women and their health care providers. The objective was to examine the fetal safety of metronidazole.

METHODS

The Israeli Teratogen Information Service prospectively collected and followed up 228 women exposed to metronidazole in pregnancy, 86.2% of whom with first-trimester exposure. Pregnancy outcome was compared with that of a control group, who were counseled during the same period for nonteratogenic exposure.

RESULTS

There was no difference in the rate of major malformations between the groups (3/190; 1.6% [metronidazole] vs. 8/575; 1.4% [control], P = 0.739). The rate of major malformations did not differ between the groups even after including elective terminations of pregnancy due to prenatally diagnosed malformations (5/192; 2.6% [metronidazole] vs. 12/579; 2.1% [control], P = 0.777). A reduced neonatal birth weight was found in the metronidazole group compared with controls without significant differences in the rate of prematurity or in gestational age at delivery. The mean birth weight was lower in the metronidazole group when comparing the subgroup of term infants.

CONCLUSIONS

This study confirms that metronidazole does not represent a major teratogenic risk in humans when used in the recommended doses.

Clinical pharmacokinetics of metronidazole and other nitroimidazole anti-infectives

Metronidazole was first introduced for the treatment of trichomoniasis. Its therapeutic use has subsequently been expanded to include amoebiasis, giardiasis and, more recently, anaerobic infections. Most of the early pharmacokinetic studies employed nonspecific assays such as microbiological and chemical assays. These assays were not able to differentiate the parent drug from the metabolites or other interfering substances. Pharmacokinetic data obtained through the use of specific chromatographic techniques provide the basis for this review of recent pharmacokinetic findings concerning metronidazole and other nitroimidazole antibiotics. When given intravenously or orally at usual recommended doses, metronidazole attains concentrations well above the minimum inhibitory concentrations for most susceptible micro-organisms. The drug has an oral bioavailability approaching 100%. Rectal and vaginal administration results in a smaller amount of drug absorption and lower serum concentrations. Metronidazole has limited plasma protein binding but can attain very favourable tissue distribution, including into the central nervous system. The drug is extensively metabolised by the liver to form 2 primary oxidative metabolites: the hydroxy and acetic acid metabolites. The kidney is responsible for the elimination of only a small amount of the parent drug; however, normal excretion of the 2 metabolites is dependent on the integrity of kidney function. The metabolism of metronidazole was found to vary among patient groups. Preterm and term infants have lower total body clearance (CL) and prolonged elimination half-lives. However, children older than 4 years old were observed to have pharmacokinetic parameters similar to those in adults. Reduced CL was also observed in children who are malnourished. Elderly patients have reduced renal excretion of both the parent drug and hydroxy metabolite. Pharmacokinetic parameters in pregnant patients were not significantly different from those in nonpregnant women; however, the drug is distributed into breastmilk and the infant will be exposed to the drug through the nursing mother. Patients undergoing gastrointestinal surgery or having enteric diseases and those who are hospitalised or critically ill also have altered pharmacokinetics. Metabolism of the drug is reduced in patients with liver dysfunction, giving delayed production of metabolites. In contrast, renal failure has little effect on the elimination of the parent drug, but affects the excretion of the metabolites more significantly. Haemodialysis was found to remove a substantial amount of the metronidazole while the effect of peritoneal dialysis was more limited. Energy and protein deficient diets as well as occupational exposure to gasoline did not alter metronidazole pharmacokinetics. However, the effect of alcohol consumption on metronidazole CL requires further study.(ABSTRACT TRUNCATED AT 400 WORDS)

Rationale for the use of antimicrobial agents in periodontal disease

The traditional approach to treating dental decay and periodontal disease has often focused on caries, neglecting periodontal infection. The past 15 years have seen significant advances in the treatment of periodontal disease with antimicrobial therapy, both with and without more traditional debridement or surgery. This article presents an overview of the use of antimicrobials, including an examination of treatment philosophies and the diagnosis of periodontal infection.

Skin diseases aggravated by pregnancy

During pregnancy, immunologic, endocrine, metabolic, and vascular changes occur that make the pregnant woman susceptible to aggravation of certain skin diseases. These diseases can be organized into five broad categories: infections, diseases of altered immunity, metabolic diseases, connective tissue disorders, and miscellaneous conditions. A discussion of how each of these diseases is altered by pregnancy and how treatment may differ during gestation is presented.

Prenatal adverse effects of various drugs and chemicals. A review of substances of frequent concern to mothers in the community

Using the number of calls to the Canadian Motherisk Program as an indicator of the drugs and chemicals frequently of concern to mothers during pregnancy, the risks to the fetus of exposure to these compounds have been reviewed. The drugs which were of concern, and have been proven to be teratogenic, included alcohol, alkylating and antimetabolite agents, stilboestrol, disulfiram, heparin, lithium carbonate, phenytoin, tretinoin (retinoic acid), troxidone and valproic acid. For other compounds studied, there was either no data in the literature or no clear evidence of teratogenicity. The combination of doxylamine and pyridoxine, for example, has been associated with limb reduction defects in isolated case reports: cohort and case-control studies have failed to show a higher-than-baseline risk of malformations. In some cases of exposure to compounds with no known teratogenic potential, other adverse effects to the fetus are possible, and these effects are discussed in detail. In conclusion, when advising a pregnant woman about the potential teratogenic effect of a particular drug or chemical exposure, the health professional should also discuss other factors such as age, obstetric and medical history and the history of other exposures (including alcohol and smoking). In every pregnancy there is a 1 to 5% risk of mayor malformations, and even if the exposure does not appear to increase the teratogenic risk, such a risk still exists.

Host-mediated transformation: metronidazole

To evaluate the possible genotoxic effects of the drug, metronidazole in the fetus, we employed the hamster embryo host-mediated assay. Pregnant golden Syrian hamsters were fed metronidazole at doses ranging from 200 mg/kg to 900 mg/kg on days 11 and 12 of pregnancy. Embryonic cells obtained from the treated animals were studied in vitro for morphologic evidence of transformation. To further assess the significance of the in vitro finding, cells from mass culture were tested for their ability to grow in soft agar. The drug-treated cells and cells previously treated with diethyl nitrosamine (positive controls) showed comparable growth characteristics. To confirm the neoplastic potential of the drug-treated embryonic cells, subcultivated cells from the tenth passage were implanted into nude mice and irradiated immunosuppressed hamsters. Cells from the 300 mg/kg treatment produced fibrosarcoma in nude mice but not in the irradiated hamsters. Cells from no other dose level employed in the study produced tumors in host animals. It is concluded that metronidazole is capable of vertical transmission of potential genotoxic effects to the fetus.

Effects of drugs and chemicals on the fetus and newborn (2)

Physicians have become increasingly aware of the side effects of specific drugs. Obstetricians and family physicians should especially be cognizant of the implications of the administration of any drug, not only for the pregnant mother but also for the unborn child. In this second installment of our two-part article, we conclude our review of drugs, chemicals, and environmental pollutants that may affect the fetus or newborn.

Metronidazole in periodontitis. I. Clinical and bacteriological results after 15 to 30 weeks

The statistical association of certain anaerobic organisms such as black pigmented bacteroides (BPB) species and spirochetes with clinical signs of active periodontitis, i.e. bleeding upon probing and bone loss, suggests that the lesions may actually reflect a "specific infection" involving these or unidentified species. All the known oral species of BPB and spirochetes are anaerobes which suggests that antimicrobial treatment directed specifically against anaerobes might be effective in periodontal therapy. In this report, the short-term results of metronidazole treatment plus mechanical debridement in patients with extensive periodontal disease and of a double-blind clinical study in which metronidazole plus mechanical debridement is compared to placebo plus mechanical debridement are described. The findings indicate that 1 week of systemic metronidazole can optimize the clinical reduction of pockets and increase the apparent attachment in periodontitis patients who receive concurrent mechanical debridement of their root surfaces. In patients with extensive clinical involvement, metronidazole resulted in a significant reduction in the number of sites exhibiting pocket depths and attachment loss greater than or equal to 7 mm. When metronidazole plus mechanical debridement was compared with placebo plus mechanical debridement in a double-blind study, the metronidazole patients exhibited a significant improvement in those sites initially greater than or equal to 7 mm. The beneficial effect of the metronidazole was associated with a significant and sustained reduction of certain anaerobic organisms such as Bacteroides gingivalis and the large spirochetes. These data indicate that treatment aimed specifically toward the anaerobic component of the plaque flora can be associated with impressive clinical improvements 15 to 30 weeks after the initiation of treatment.

Placental transfer of metronidazole in the first trimester of pregnancy

Concentrations of metronidazole and its hydroxy metabolite (I) were determined by a specific chromatographic method in blood, placenta and fetus from 10 women receiving oral metronidazole prior to legal first trimester abortion. In one woman given 2 g of metronidazole 9 hours before abortion, placenta and plasma levels were 6.6 micrograms/g and 13.4 micrograms/ml, respectively. The corresponding values for the hydroxy metabolite (I) were 1.8 micrograms/g and 5.6 micrograms/ml. In nine women receiving 400 mg metronidazole 1 hour before abortion, concentrations of metronidazole in plasma ranged from less than 0.1 to 9.4 micrograms/ml, in placenta from less than 0.1 to 6.3 micrograms/g, and in a fetal tissue from 1.9 to 3.0 micrograms/g. The concentrations of hydroxy metabolite (I) in plasma and placenta and fetal tissue all ranged below those of metronidazole.