MONTEREY, CALIF. — Two (2%) of 98 pregnant women being admitted for labor or a scheduled C-section were colonized with methicillin-resistant Staphylococcus aureus in a pilot study, Dr. Richard H. Beigi reported in a poster presentation at the annual meeting of the Infectious Diseases Society for Obstetrics and Gynecology.
The results of the study are consistent with a 2%–4% colonization rate for methicillin-resistant S. aureus (MRSA) found in some populations, though higher rates have been seen in select populations. These are among the first data on MRSA in women entering labor and delivery wards, said Dr. Beigi, who performed the study at MetroHealth Medical Center, Cleveland, and now is at Magee-Women's Hospital, Pittsburgh.
“It emphasizes the fact that we need to have very good hand hygiene,” he said in an interview at the poster session. The study was funded by Steris Corp., which makes a hand hygiene product.
The 2% rate provides a baseline for comparisons as the incidence of MRSA is tracked in labor and delivery over time. Ongoing surveillance is warranted given the increasing rates of MRSA in other specialties and the limited number of effective drug treatments for complications of MRSA infection, said Dr. Beigi and his associates.
Of the 96 women, 21 (22%) had S. aureus detected in samples from the anterior nares. Two (10%) of the 21 with S. aureus had MRSA. One of the women with MRSA worked in a hospital, and the other had no contact with a hospital or hospital workers as a potential source for her MRSA colonization.
Eight (38%) of the 21 isolates with S. aureus demonstrated inducible clindamycin resistance, and one of these was a strain with MRSA. The clinical implications of this are unclear, but MRSA plus clindamycin resistance would further narrow choices for therapy.
In a subset of 28 women who also had cultures obtained from the outer third of the vagina, 23 (82%) had concordant findings, meaning that if they were positive or negative for S. aureus in one anatomical site, they had the same result at the other site.
Six postpartum infections potentially were attributable to S. aureus—two cases of mastitis and four wound infections after C-section. Postpartum infection rates were twice as high in women with S. aureus (10%), compared with uncolonized women (5%), but the difference was not statistically significant. A larger study might show a significant difference in infection rates, Dr. Beigi suggested.