antimicrobials in pregnancy

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Hi,

In the following discussion, each agent is categorized as:

* probably safe: i.e., there is substantial experience with the use of the agent in pregnancy, and no known adverse effects for the fetus;

* use with caution: i.e., there are documented or potential risks to the fetus, but use of the agent is justified in certain clinical situations;

* contraindicated: i.e., since risks to the fetus are very great, and suitable

alternative agents are available, the drug should never be used in pregnancy.

Penicillins and cephalosporins

As a group penicillins are probably the safest antimicrobials during pregnancy.

The older penicillins and cephalosporins have been used extensively for several decades in the treatment of infections in pregnant women. No evidence of any adverse effects to the fetus have been documented. Even agents with broad spectrum activity such as piperacillin and mezlocillin, as well as those combined with beta lactamase are safe.

Erythromycin,

This macrolide is often given to penicillin allergic patients. It has been used extensively for treatment of infections in pregnant women. There is no evidence suggesting any harmful effects to the fetus and they can be considered safe. Erythromycin estolate,however, has been associated with cholestatic hepatitis in and should not be used.

Aminoglycosides

Maternal administration can result in toxic fetal blood levels, but this can be avoided by using lower divided doses. Although both nephrotoxicity and ototoxicity have been reported in preterm newborns following maternal exposure to gentamicin or streptomycin, congenital defects resulting from prenatal exposure have not been confirmed. While aminoglycosides should be used with caution, current information suggests that in any serious infection where aminoglycoside therapy is indicated, the benefits would outweigh potential risks.

Aztreonam is used primarily as an aminoglycoside alternative.It is not associated with renal or nephrotoxicity and although there are no well-controlled human studies, it is not teratogenic in rodents.

Cotrimoxazole

(Trimethoprim+Sulfamethoxazole)

Trimethoprim is a folate antagonist and has been shown to be teratogenic in rats. Thus there are theoretical concerns about its use in pregnancy, especially in the first trimester. The sulfonamides have been used extensively in pregnancy. Potential toxicities of this class of drugs include hemolysis in individuals with glucose-6-phosphatase (G6PD) deficiency, and an increased risk of kernicterus in the newborn because of displacement of bilirubin from albumin-binding sites. There are a number of studies which have reported on the use of this combination to treat bacteriuria in pregnancy.These studies all support the observation that it is a safe, effective agent.Thus, while caution is recommended,in most instances where cotrimoxazole would be an appropriate therapeutic agent the benefits

outweigh the risks.

Metronidazole

Metronidazole has been shown to be carcinogenic inanimals, but there have been no reports of adverse effects associated with its use in pregnancy. While caution is again recommended, the information available suggests that its use is safe. Metronidazole is an appropriate therapy for pregnant women with trichomoniasis.

In the case of giardiasis, a pregnant woman with asymptomatic infection should have therapy delayed until after delivery. For, symptomatic giardiasis infection, however, it would be appropriate to treat the patient with metronidazole.

Fluroquinolones

Although no teratogenic effects have been demonstrated in animals, these drugs are reported to be associated with irreversible arthropathy and cartilage erosion in animals. Accordingly, they have not been recommended for use during pregnancy except cautious use for the treatment of multiresistant infections.

Nitrofurantoin

While there is a controversy regarding the use of nitrofurantoin in pregnancy it has been used extensively for the management of urinary infections in pregnancy and has been documented to be an effective and safe agent.

Antifungal agents

Vaginal candidiasis is common during pregnancy. Three commonly used agents for its treatment are clotrimazole, miconazole and nystatin. There have been no congenital malformations reported in association with their use.

Tetracyclines, for reasons well known are contraindicated in pregnancy.

Regards,

Dr. Smita

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