Screening for Streptococcus agalactiae Colonization

We used the vaginal and rectal swabs to screen the S. agalactiae colonization, as reported previously (Haimbodi et al. 2021 (link); Filkins et al. 2020 ). The cotton-tipped sterile swabs were used for sampling by a qualified clinician. A Todd Hewitt Broth (Sigma, Germany) containing 8 μg/ml of gentamycin, 15 μg/ml of nalidixic acid, and 5% sheep blood was used to transport the specimens at 2–8 °C (Filkins et al. 2020 ). After 24 h of incubation of the transport media at 37 °C under 5% CO₂, 50 μl of the medium was inoculated on 5% sheep blood agar plates (Condalab, Spain), containing the above mentioned antibiotics and was incubated at 37 °C under 5% CO₂ for 24 h. The S. agalactiae identification was confirmed by the observation of the β-hemolytic or non-hemolytic whitish-grey translucent large colonies and the standard microbiological and biochemical tests. These tests included gram staining, catalase, growth on bile esculin agar, hydrolysis of Hippurate, CAMP, and susceptibility to bacitracin (0.04 units) and trimethoprim (1.25 µg)-sulfamethoxazole (23.75 µg) (Tille 2017 ). S. agalactiae ATCC 12403 was used as positive control in this test.