This study showed the prevalence of GBS colonization in pregnant women in Jiangsu, East China. The pregnant women among 25-29 years old and aged over 40 years should pay more attention in this area. And we compared the difference of GBS infection between culture and PCR. PCR was expected to become a quick method in pregnancy women conventional detection of GBS infection. The GBS-positive samples which detected by culture were all sensitive to penicillin.
GBS infection can be transient or persistent during pregnancy, which inevitably leads to different results of GBS in the same pregnant woman at different times of pregnancy[1,12]. Therefore, we should choose the same stage of pregnant women when studying the infection rate of GBS. There are regional differences of GBS colonization in pregnant women. For example, the reported prevalence of GBS for Africa is 22.4%, Southeast Asia is 11.1% and Taiwan is 23.7%[13-14]. Unfortunately, large-scale multicenter epidemiological studies on maternal GBS colonization in mainland China are still rare.
So far, there have been many regional studies on the rate of GBS colonization in China. It was reported that the prevalence of GBS for Beijing was 7.1% and Qingdao in Shandong Province was 10.61% in Northern China[16-17]; Shanghai was 3.7% and Nanjing was 4.16% in Eastern China[18-19]; Chongqing was 7.05% and Chengdu in Sichuan Province was 5.02% in Southern China[20-21]. The infection rates of GBS vary widely in different parts of China, and the prevalence of GBS in northern region is significantly higher than the eastern region. In our study, the rate of GBS colonization obtained by culture was 3.5% and by PCR was 8.7%, in Jiangsu, China. The average positive rate of GBS infection was 6.4%. The rate in our study was lower than the northern region. The main reason for this difference may be related to local economic levels and environmental factors. Another important factor is the neglect of detection method of GBS.
In our study, the rate of GBS colonization obtained by culture only (3.5%) was much lower than the rate obtained by PCR (8.7%) in Jiangsu, China. This is mainly because PCR is a rapid method which more sensitive and specific than culture. It may be due to the presence of nonviable GBS or low bacterial load in vaginal swabs, which cannot be detected by culture, but their DNA could be present for PCR amplification[22-23]. Some pregnant women colonized by GBS might be missed only using a culture method.
Among the different age groups, the 25-29 age group and people aged over 40 years should pay more attention. It may be related with the sexually active life, history of induced abortion and higher estrogen levels during pregnancy in these age groups. These factors can cause micro-environmental changes in the genital tract bacteria. This phenomenon will be continue to focus on in future research.
IAP agents and dosing should be administered basing on the test results of GBS among pregnant women according to the Centers for Disease Control (CDC) guidelines. Penicillin remains the agent of choice for IAP, with ampicillin as an acceptable alternative in China. Antimicrobial susceptibility testing should be ordered for antenatal GBS cultures performed on penicillin-allergic women at high risk for anaphylaxis. Then, the sensitive antibiotic could be chosen according to the results of antimicrobial susceptibility testing.
Previous studies on GBS bacteremia in adults during 2002 to 2010 in USA had shown that erythromycin and clindamycin resistance occurred in 43.6% and 39.7% of cases, respectively. And the prevalence of resistance to erythromycin and clindamycin from Taiwan for the period 2006– 2008 was 58.3% and 57.9%, respectively . In our study, the prevalence of resistance to erythromycin and clindamycin was 77.5% and 68.3%, respectively. It was higher than the prior studies. The goal of our research is pregnant women, which is a special group of people. It may be the main cause of this difference.