Winners of the 2014 JA Medals for excellence.

Abstract

From October 2007 to September 2008, we collected the specimen from 362 patients with lower respiratory tract infections in 14 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and patients' characteristics. Of 413 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in infection, 412 strains were examined. The isolated bacteria were: Staphylococcus aureus 65, Streptococcus pneumoniae 90, Haemophilus influenzae 88, Pseudomonas aeruginosa (non-mucoid) 53, P. aeruginosa (mucoid) 13, Klebsiella pneumoniae 19, and Moraxella catarrhalis 41. Of 65 S. aureus strains, those with 2 μg/mL or less of MIC of oxacillin (methicillin-susceptible S. aureus: MSSA) and those with 4 μg/mL or more of MIC of oxacillin (methicillin-resistant S. aureus: MRSA) were 38 (58.5%) and 27 (41.5%) strains, respectively. Against MSSA, imipenem had the most potent antibacterial activity and inhibited the growth of all strains at 0.063 μg/mL or less. Against MRSA, vancomycin and arbekacin showed the most potent activity and inhibited the growth of all the strains at 2 μg/mL. Linezolid also showed the same activity as them. Carbapenems and penems showed the most potent activities against S. pneumoniae and in particular, panipenem inhibited the growth of all the strains at 0.063 μg/mL or less. Imipenem and faropenem also had a preferable activity and inhibited the growth of all the strains at 0.25 and 1 μg/mL, respectively. In contrast, there were high-resistant strains (MIC: over 128 μg/mL) for erythromycin (38.2%) and clindamycin (18.0%). Against H. influenzae, levofloxacin showed the most potent activity and its MIC90 was 0.063 μg/mL or less. Meropenem showed the most potent activity against P. aeruginosa (mucoid) and its MIC90 was 0.5 μg/mL. Against P. aeruginosa (non-mucoid), tobramycin had the most potent activity and its MIC90 was 2 μg/mL. Against K. pneumoniae, cefozopran had the most potent activity and inhibited the growth of all the strains at 0.063 μg/mL or less. Also, all the antibacterial agents except ampicillin generally showed a potent activity against M. catarrhalis and the MIC90 of them were 2 μg/mL or less. The approximately half the number (45.9%) of the patients with respiratory infection were aged 70 years or older. Bacterial pneumonia and chronic bronchitis accounted for 44.8% and 31.5% of all the respiratory infection, respectively. The bacteria frequently isolated from the patients with bacterial pneumonia were S. aureus (21.9%), S. pneumoniae (20.8%), and H. influenzae (18.6%). S. pneumoniae (27.1%), H. influenzae (24.0%) and P. aeruginosa (17.8%) also were frequently isolated from the patients with chronic bronchitis. Before the drug administration, the bacteria frequently isolated from the patients were S. pneumoniae (23.9%) and H. influenzae (23.6%). The bacteria frequently isolated from the patients treated with macrolides were S. pneumoniae, and their isolation frequencies were 34.8%.