RT Journal Article SR Electronic(1) A1 Kawaguchiya, Mitsuyo A1 Urushibara, Noriko A1 Aung, Meiji Soe A1 Shinagawa, Masaaki A1 Takahashi, Satoshi A1 Kobayashi, NobumichiYR 2017 T1 Serotype distribution, antimicrobial resistance and prevalence of pilus islets in pneumococci following the use of conjugate vaccines JF Journal of Medical Microbiology, VO 66 IS 5 SP 643 OP 650 DO https://doi.org/10.1099/jmm.0.000479 PB Microbiology Society, SN 1473-5644, AB Purpose. In Japan, the 7-valent pneumococcal vaccine (PCV7) was introduced in 2010 and, in 2013, the PCV7 was replaced with the 13-valent pneumococcal vaccine (PCV13). This study was conducted to investigate serotypes, antimicrobial resistance and prevalence of pilus islets in pneumococcal isolates from inpatients in a Japanese tertiary hospital. Methodology. From April 2011 to February 2016, 151 isolates [95 (18 children, 77 adults) and 56 (19 children, 37 adults) in the PCV7 and PCV13 periods, respectively] were collected. All isolates were serotyped using genetic methods and were tested for susceptibility to 18 antimicrobials. Unaltered penicillin-binding protein (PBP) genes, macrolide resistance genes and pilus islets were identified by PCR. Results. Between the two periods, the prevalence of non-PCV13 serotypes was shown to increase from 50.0 to 78.9 % in children, and serotype 3 increased from 14.3 to 24.3 % in adults. Six of seven isolates from invasive diseases were assigned to non-PCV13 serotypes. Overall, multidrug resistance (MDR) was detected in 46.4 % of isolates, which included the dominant non-PCV13 serotypes 6E, 15A and 23A (prevalence≥75.0 %). gPRSP (three altered genes pbp1a, pbp2b and pbp2x) and macrolide resistance genes [erm(B) and/or mef(A/E)] were detected in 35.8 and 93.4 % of all isolates, respectively. Pilus islets [PI-1 (clade I, II and III) and/or PI-2] were found in 22.5 % (34/151) of isolates belonging to six different serotypes (19F, 23F, 19A, 6E, 15B and 35B) and 88.2 % (30/34) of these exhibited MDR. Conclusion. This study revealed the spread of MDR in several non-PCV13 serotypes and in isolates with pilus islets., UL https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.000479