Clinical Review

2016 Update on infectious disease

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Recent studies offer new data on treatments for surgical-site infections after cesarean delivery, postpartum endometritis, and chlamydia infection, while a vaccine for hepatitis E with long-term efficacy has promise for reducing occurrence of this common infection in developing countries.

In this article

• Antibiotics for postpartum endometritis
• Azithromycin vs doxycycline for chlamydia
• Insect repellents to prevent Zika virus


 

References

In this Update, we review 4 interesting articles on infectious disease that have immediate implications for our clinical practice. The first article addresses the issue of which antiseptic is most effective in preventing surgical-site infections (SSIs)after cesarean delivery. The second report is an excellent review of alternative oral and intramuscular antibiotics that might be used for treatment of endometritis in low-resource countries. The authors of the third article present an interesting comparison of azithromycin versus doxycycline for the treatment of uncomplicated chlamydia infection. The final article describes a recently developed vaccine for prevention of hepatitis E. Although this infection is distinctly uncommon in the United States, it is endemic in developing nations, where hepatitis E is an important cause of maternal mortality. A vaccine to prevent this infection is certainly welcome.

Chlorhexidine-alcohol is superior to iodine-alcohol for reducing SSIs after cesarean deliveryTuuli Mg, Liu J, Stout Mj, et al. A randomized trial comparing skin antiseptic agents at cesarean delivery. N Engl J Med. 2016;374(7):647-655.

In the United States, cesarean delivery is the most commonly performed major surgical procedure, with 32.7% of births--or 1.3 million--occurring in this fashion in 2013.1,2 In general, for all surgical procedures, the SSI rate is 2% to 5%, with the rate rising to 5% to 12% for cesarean delivery, especially in obese patients.3-6 Not only do SSIs increase morbidity for the patient but they also contribute to high medical costs, with an estimated additional expense of $3,529 per cesarean-associated infection.7

Skin pathogens are a major source of SSIs. Choosing the proper antiseptic has the potential to decrease infection risk. While current guidelines recommend use of an antiseptic containing alcohol, it is unclear which disinfectant is the most effective agent to combine with the alcohol.3

Most trials evaluating preoperative antiseptic skin preparation have studied patients undergoing general surgery procedures. A well-designed trial by Darouiche and coauthors demonstrated that chlorhexidine was superior to iodine when used as an antiseptic for skin preparation.8 Interestingly, however, this trial, like most others, compared chlorhexidine-alcohol to iodine without alcohol. It is therefore unclear whether the chlorhexidine or the alcohol is responsible for the enhanced antiseptic effect.

Details of the studyIn the single-center randomized trial conducted by Tuuli and colleagues, patients were assigned to preoperative skin antisepsis with either chlorhexidine-alcohol (2% chlorhexidine gluconate with 70% isopropyl alcohol) or iodine-alcohol (8.3% povidone-iodine with 72.5% isopropyl alcohol). Antiseptic was applied according to the manufacturer's instructions, with a standard wait time of 3 minutes between application and skin incision. However, wait time was eliminated for patients undergoing emergency cesarean delivery. Additionally, patients received standard, weight-based preoperative antibiotic prophylaxis (agent not specified).

The authors estimated the necessary sample size for the trial by assuming an 8% baseline SSI rate and an anticipated 50% reduction of infection in the chlorhexidine-alcohol group. Exclusion criteria included a known allergy to chlorhexidine, alcohol, iodine, or shellfish or a preexisting skin infection adjacent to the operative site.

In addition to assessing the primary outcome of SSI with the 2 preparations, the authors conducted 4 prespecified subgroup analyses. These subgroups were based on: type of cesarean delivery (scheduled vs unscheduled), body weight (obese vs nonobese), type of skin closure (subcuticular suture vs staples), and presence or absence of chronic medical conditions (diabetes, hypertension, renal disease). Additionally, a post hoc analysis was performed, comparing women with diabetes (gestational and pregestational) to those without diabetes.

A total of 1,636 pregnant women were screened for eligibility. Of these, 489 women were excluded because they did not meet inclusion criteria or declined to participate or because informed consent could not be obtained. Baseline characteristics were similar across both groups.

Patients were followed for 30 days after surgery. A total of 1,082 women (94.3% of sample size) completed the follow-up. Among these patients, the rate of SSI was significantly lower in the chlorhexidine-alcohol group (4.3%) compared with the iodine-alcohol group (7.7%, P = .02).

In the subgroup analyses, the frequency of SSI remained lower for the chlorhexidine-alcohol group than for the iodine-alcohol group. These reductions were not affected by whether the cesarean was scheduled or unscheduled, the presence or absence of obesity, the type of skin closure, the presence of chronic disease, or diabetes status.

Several secondary outcomes also were examined in this study. There were no significant differences between the 2 antiseptic groups with respect to rates of endometritis, hospital readmission for infection-related complications, length of hospital stay, use of other health care services (such as emergency department visits, additional wound surgery, and home health services), and rates of other wound complications (seroma, hematoma, and cellulitis). Patients in the chlorhexidine-alcohol group were significantly less likely than those in the iodine-alcohol group to have physician office visits for concerns about possible wound complications (P = .009).

The authors concluded that the use of chlorhexidine-alcohol was superior to iodine-alcohol in preventing SSI after cesarean delivery.

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