INFECTIOUS DISEASE

Anaerobes usually do not pose a major threat to the fetus or neonate, but are particularly likely to lead to pelvic abscess in women who require a cesarean delivery in the face of preexisting intrauterine infection.⁵

Accordingly, the initial antibiotic therapy for chorioamnionitis typically targets the 2 organisms most likely to infect the fetus/neonate—group B streptococci and E coli. The antibiotic regimen of ampicillin plus gentamicin provides excellent, and inexpensive, coverage of these pathogens. The addition of a drug such as clindamycin or metronidazole provides a reassuring measure of coverage against anaerobes in women who require a cesarean delivery.¹

Traditionally, patients with chorioamnionitis have been treated with IV antibiotics until they have been afebrile and asymptomatic for 24 hours.

Chapman and Owen,⁶ who were among the first to suggest that a shortened course of treatment might be as effective as a more extended course, assessed the effectiveness of a single post-partum dose of cefotetan in women who were treated intrapartum for chorioamnionitis and who delivered vaginally. The rate of treatment failure was 11% in the single-dose group and 3.7% in the women treated with multiple doses of cefotetan until they had been afebrile for 24 hours. This observed difference was not statistically significant (P = .27), but the study lacked sufficient power to firmly establish the safety and effectiveness of short-course therapy.

A trial of “no therapy” vs “extended therapy” in women with chorioamnionitis who delivered by cesarean found the rate of treatment failure was 21.8% in the “no therapy” group and 14.8% in the women who received clindamycin plus gentamicin for at least 24 hours postoperatively.⁷

Again, this observed difference was not statistically significant (P = .32), but the power of the investigation was limited.

This more recent study was sufficiently large and included a reasonable number of women who delivered both vaginally and abdominally.

Anti-anaerobic coverage critically important. Complications related to persistent infection developed in 2 patients in the short-course group who had cesarean deliveries: pelvic abscess and incisional abscess. In both instances, the patients did not receive the dose of clindamycin specified in the protocol, illustrating the critical importance of proper anti-anaerobic coverage in patients who require abdominal delivery.

Short-course therapy offers advantages in terms of ease of administration and cost savings compared with more extended treatment regimens.

Whether short courses of single agents, such as the broad-spectrum cephalosporins, penicillins, and carbapenems, would be as effective as ampicillin plus gentamicin plus clindamycin remains to be determined.

CDC data show “herd” immunity, thanks to varicella vaccination policy

Nguyen HQ, Jumaan AO, Seward JF. Decline in mortality due to varicella after implementation of varicella vaccination in the United States. N Engl J Med. 2005;352:450–458.

Question all women of reproductive age about varicella. Women who lack a convincing history of natural infection should have a serologic test for varicella-zoster IgG. If immunity is not evident, they should be vaccinated prior to attempting pregnancy.

This study demonstrates that, through the phenomenon of herd immunity, universal vaccination has significantly lowered the overall risk of varicella-related mortality in the general population. Universal childhood varicella vaccination was recommended by the Centers for Disease Control and Prevention in 1995; the rate of death due to varicella, either as the underlying cause or the contributing cause, fluctuated from 1990 through 1998, and then sharply declined.

Data from the National Center for Health Statistics Multiple Cause-of-Death Mortality for 1990 through 2001 reveal reduced varicella-related mortality in all age groups younger than 50 years. The greatest reduction (92%) was in children 1 to 4 years of age. Most deaths due to varicella were among persons who did not have an underlying high-risk condition and who would have been excellent candidates for vaccination.

Life-threatening in adults, especially pregnant women

Varicella usually is a relatively mild, self-limited disease of childhood. However, in immunocompromised persons and even in otherwise healthy adults, varicella can cause life-threatening complications such as severe pneumonia and encephalitis. Pneumonia develops in approximately 20% of adults who contract varicella, and encephalitis in approximately 1%. In the era before acyclovir was available, as many as 20% of persons with these complications died.⁸

Unique set of problems during pregnancy. Although pregnant women are not more likely than nonpregnant women to contract varicella or even to develop pneumonia or encephalitis, they do have a higher mortality if they experience these complications.

When varicella occurs during the first half of pregnancy, anomalies or spontaneous abortions occur in 1% to 2% of fetuses. Moreover, when the mother has varicella near or at the time of delivery, neonatal varicella develops in as many as 20% of infants, manifested as a mucocutaneous exanthema, pneumonia, encephali-tis, or disseminated visceral infection. Even with acyclovir treatment, severe morbidity and death can occur in affected neonates.⁸