Tohoku J. Exp. Med., 2010, 220(1)

Trends in Antimicrobial Susceptibility of Streptococcus pneumoniae in the Tohoku District of Japan: A Longitudinal Analysis from 1998 to 2007

KAZUMASA SUZUKI,¹ KATSUSHI NISHIMAKI,² KAORI OKUYAMA,¹ TADASHI KATOH,³ MINORU YASUJIMA,⁴ JUNICHI CHIHARA,⁵ AKIRA SUWABE,⁶ YOKO SHIBATA,⁷ CHOICHIRO TAKAHASHI,⁸ HIROAKI TAKEDA,⁹ SHIRO IDA,¹⁰ MITSUO KAKU,² AKIRA WATANABE,¹¹ TOSHIHIRO NUKIWA,¹² KAZUNAO NIITSUMA,¹³ KEIJI KANEMITSU,¹⁴ MOTOAKI TAKAYANAGI¹ and ISAO OHNO¹

¹Department of Pathophysiology, Tohoku Pharmaceutical University, Sendai, Japan
²Department of Infection Control and Laboratory Diagnostics, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
³Laboratory of Synthetic Medical Chemistry, Tohoku Pharmaceutical University, Sendai, Japan
⁴Department of Laboratory Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
⁵Department of Clinical and Laboratory Medicine, Akita University Graduate School of Medicine, Akita, Japan
⁶Department of Laboratory Medicine, Iwate Medical University School of Medicine, Morioka, Japan
⁷Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan
⁸Department of Clinical Laboratories, Yamagata University Hospital, Yamagata, Japan
⁹Department of Respiratory Medicine, Yamagata Saisei Hospital, Yamagata, Japan
¹⁰Department of Internal Medicine, General Minami Tohoku Hospital, Iwanuma, Japan
¹¹Research Division for Development of Anti-infective Agents, Institute of Development Aging and Cancer, Tohoku University, Sendai, Japan
¹²Department of Respiratory Medicine, Internal Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
¹³Department of Internal Medicine, Fukushima Prefecture Aizu General Hospital, Aizuwakamatsu, Japan
¹⁴Department of Clinical Laboratory Medicine, Fukushima Medical University, Fukushima, Japan

Streptococcus pneumoniae is a common cause of respiratory tract infections (RTIs). The prevalence of Streptococcus pneumoniae strains with reduced susceptibility to antimicrobial agents has dramatically increased worldwide. Susceptibility to nine antimicrobial agents and serotypes were determined among 1,644 Streptococcus pneumoniae strains isolated from patients with RTIs in the Tohoku district of Japan from October to December every year from 1998 to 2007. The prevalence of penicillin G-nonsusceptible Streptococcus pneumoniae (PNSP) strains increased gradually from 48.5% in 1998, reached a statistical peak in 2004 (65.1%) and then decreased to 51.5% in 2007. Streptococcus pneumoniae strains with each serotype 3, 6, 19 and 23 were constantly detected, and the distribution of these serotypes in PNSP strains did not significantly change during the study period. A trend of Streptococcus pneumoniae strains nonsusceptible to other β-lactams tested was similar to that of PNSP strains, except for cefditoren, to which the resistance rate was < 20% throughout the analysis period. The prevalence of strains nonsusceptible to erythromycin and minocycline were consistently > 60%. Almost all penicillin G-resistant Streptococcus pneumoniae (PRSP) strains were resistant to both erythromycin and minocycline throughout the analysis period. The prevalence of strains resistant to fluoroquinolones tested were < 3% over the study period. Our longitudinal surveillance demonstrated for the first time that decreased prevalence of both β-lactam- and multidrug-resistant strains has been occurring since 2004 in a region of Japan. Careful monitoring of antimicrobial susceptibility of Streptococcus pneumoniae should be continued.

keywords —— S. pneumoniae; susceptibility; penicillin resistance; serotype; multidrug resistance

© 2010 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2010, 220, 47-57

Correspondence: Isao Ohno, M.D., Ph.D., Department of Pathophysiology, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan.

e-mail: iohno@tohoku-pharm.ac.jp