240 Infection with Group B Streptococcus (GBS), also known as Streptococcus agalactiae, may cause invasive diseases with high mortality (1). Particularly, GBS serotypes IV and VI have been implicated in invasive diseases and reported to have a high prevalence of macrolide resistance (2,3). Increasing resistance of GBS to quinolones and macrolides has also been reported worldwide (4,5). GBS infection is associated with high mortality in elderly people, pregnant women, neonates, and those with comorbidities (1); however, to our knowledge, no data till date suggests that quinolone and macrolide resistance in GBS infection increases the mortality risk. Quinolones and macrolides constitute approximately 50% or more of all oral antibiotics consumed in Japan (6), and the rate of quinolone and macrolide resistance in GBS isolates has been reported to be as high as 20%–30% (7). Thus, infectious diseases caused by quinolone- and macrolide-resistant GBS may potentially hold some risk of treatment failure. Since GBS serotyping and genome analysis are not routinely performed in the clinical setting, it may be useful to predict the patient outcome based on antibiotic susceptibility. Therefore, in this study, we evaluated whether blood stream infection (BSI) caused by quinolone- or macrolide-resistant GBS is associated with high mortality. Data regarding patients with bacteremia caused by GBS and antibiotic susceptibility profile of GBS isolates were collected between January 2013 and December 2018 from 7 participating hospitals of Niigata Prefecture, Japan (Kaetsu Hospital, 261 beds; Shinrakuen Hospital, 325 beds; Sado General Hospital, 354 beds; Kashiwazaki General Hospital and Medical Center, 400 beds; Kido Hospital, 312 beds; Niigata City General Hospital, 676 beds; and Agano City Hospital, 250 beds). Duplicate isolates from the same patients in each year were excluded. BSI was defined as GBS infection confirmed by blood culture. The primary outcome was 30-day mortality from any cause. Infections occurring after 48 h or more of hospital admission were defined as hospital-acquired. Quinolone resistance was defined as levofloxacin minimum inhibitory concentration (MIC) >2 mg/L, and macrolide resistance was defned as erythromycin or clarithromycin MIC >0.25 mg/L (8), and both were measured at each hospital. For these defnitions, “intermediate” was included in “resistance,” according to the criteria of the Clinical and Laboratory Standards Institute. Chronic kidney disease stages were determined according to the Kidney Disease Outcome Quality Initiative criteria, and the estimated glomerular fltration rate was calculated using the Japanese version of the estimation equations. This study was approved by the Institutional Review Board of each participating hospital and performed in accordance with the ethical Short Communication Does Quinolone- or Macrolide-Resistant Streptococcus agalactiae Bacteremia Afect Patient Outcome? A Multicenter Cohort Study Satoru Mitsuboshi 1 * , Junichiro Date 2 , Naoki Tsuruma 3 , Hirokazu Yamaga 3 , Kazuya Watanabe 4 , Hiroko Kijima 5 , Manami Nakashita 6 , Hiroki Hosokawa 7 , and Masami Tsugita 8 1 Department of Pharmacy, Kaetsu Hospital, Niigata; 2 Department of Pharmacy, Shinrakuen Hospital, Niigata; 3 Department of Pharmacy, Sado General Hospital, Niigata; 4 Department of Pharmacy, Nagaoka Chuo General Hospital, Niigata; 5 Department of Pharmacy, Kido Hospital, Niigata; 6 Department of Pharmacy, Niigata City General Hospital, Niigata; 7 Department of Pharmacy, Agano City Hospital, Niigata; and 8 Department of Clinical Pharmacology, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan SUMMARY: The prevalence of quinolone- and macrolide-resistant Group B Streptococcus (GBS) is increasing worldwide, but the relationship between the resistance of GBS to these antibiotics and patient outcome remains unclear. Therefore, we evaluated whether blood stream infection caused by quinolone- or macrolide-resistant GBS is associated with high mortality. Our fndings in 77 patients with GBS bacteremia demonstrate that quinolone and macrolide resistance may not be risk factors for 30-day mortality. Received July 25, 2020. Accepted September 17, 2020. J-STAGE Advance Publication October 30, 2020. DOI: 10.7883/yoken.JJID.2020.589 *Corresponding author: Mailing address: Department of Pharmacy, Kaetsu Hospital, 1459-1 Higashikanazawa, Akiha-Ward, Niigata-City, Niigata 956-0814, Japan. Tel: +81250224711, Fax: +81250224760, E-mail: mitsuboshi_ s@niigata-min.or.jp Jpn. J. Infect. Dis., 74, 240-244, 2021