2016 Update on infectious disease

Study strengths and limitations The authors acknowledged that their study had some minor limitations. First, the trial was conducted at a single site, which may limit the generalizability of the findings. However, the study population was racially and economically diverse. Second, the lack of blinding among providers and participants may have introduced bias, although, as the authors explain, we would expect this bias to be largely nondirectional.

A major strength of this study is its randomized design. Another strength is that the authors included emergency cesarean deliveries in their analysis. Emergency procedures represent a substantial proportion of cesarean deliveries, and they place the patient at increased risk for SSIs because of limited time available to prepare the skin before surgery begins. Thus, it is of great interest that chlorhexidine-alcohol was so effective even in the highest-risk patients.

Several properties may make chlorhexidine superior to iodine as an antiseptic: high binding affinity for the skin, high antibacterial activity against both gram-positive and gram-negative bacteria, and longer residual effects than iodine. Additionally, iodine is inactivated by organic matter, such as body fluids, whereas chlorhexidine is not.

A recent study by Ngai and colleagues⁹ compared chlorhexidine-alcohol with iodine-alcohol for skin preparation before cesarean delivery. These authors found no difference in SSI when comparing the 2 solutions used separately or sequentially, except in morbidly obese women. In these women, sequential application of both solutions reduced the infection rate. However, this study specifically excluded emergency cesarean deliveries, making the generalizability of the results questionable.⁹

What this evidence means for practiceThis large, randomized study found chlorhexidine-alcohol to be superior to iodine-alchol in reducing the risk of SSIs after cesarean delivery. These results confirm those of previous studies from both the obstetric and general surgery literature. Although chlorhexidine-alcohol is more expensive than iodine-alcohol, we strongly recommend its use in patients having cesarean delivery.

Five effective oral and intramuscular antibiotic regimens for treating postpartum endometritis_{Meaney-Delman D, Bartlett LA, Gravett MG, Jamieson DJ. Oral and intramuscular treatment options for early postpartum endometritis in low-resource settings: a systematic review. Obstet Gynecol. 2015;125(4):789-800.}

The authors of this excellent systematic review on antibiotic treatments for early postpartum endometritis conducted their study in 3 phases. Initially, Meaney-Delman and colleagues searched the literature for reports of prospective studies that evaluated the use of oral and intramuscular (IM) antibiotics for treatment of patients who developed endometritis following either cesarean or vaginal delivery. When they discovered that these initial trials were few in number and of relatively poor quality, they reviewed more rigorous trials of intravenous (IV) antibiotics. Finally, they evaluated clinical trials that specifically identified microorganisms isolated from the uterus in patients with endometritis and used this information to help inform their recommendations for treatment options.

Details of the studyIn evaluating the trials of oral and IM antibiotics, the authors set as a standard for effectiveness a cure rate of 85%, a figure comparable to that generally achieved with IV antibiotics. They identified 2 oral antibiotic regimens that met this standard of effectiveness: amoxicillin-clavulanate (100% cure in 36 patients; 95% confidence interval [CI], 90-100) and ampicillin plus metronidazole (97% cure in 37 patients; 95% CI, 86-100).

Two studies demonstrated acceptable levels of cure with single-agent IM antibiotics: aztreonam (100% cure in 16 patients; 95% CI, 81-100) and imipenem (91% cure in 23 patients; 95% CI, 73-98). One additional trial demonstrated an acceptable clinical response rate when IV clindamycin was combined with IM gentamicin (100% cure in 54 patients; 95% CI, 94-100). By contrast, the authors noted, many different IV regimens--either as a single agent or as a drug combination--provided cure rates that equaled or exceeded 85%.

In the study's final phase, the authors provided an excellent overview of the polymicrobial nature of puerperal endometritis. As documented in multiple prior reports, the most common pathogens are the gram-negative anaerobic bacilli, such as Bacteroides and Prevotella species; the anaerobic gram-positive organisms, including Peptococcus and Peptostreptococcus species; aerobic gram-negative bacilli, such as Escherichia coli, Klebsiella pneumoniae, and Proteus species; and aerobic gram-positive cocci, such as group B streptococci, enterococci, and staphylococci.

Recommended regimens. Based on their review of clinical and microbiological studies, the authors proposed 5 oral or combined oral-IM treatment regimens that could be used in low-resource settings:

• oral clindamycin (600 mg every 6 hours)
• plus IM gentamicin (4.5 g every 24 hours)
• oral amoxicillin-clavulanic acid (875 mg every 12 hours)
• IM cefotetan (2 g every 8 hours)
• IM meropenem or imipenem-cilastatin (500 mg every 8 hours)
• oral amoxicillin (500 mg every 8 hours) plus oral metronidazole (500 mg every 8 hours).