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 (nonmucoid) 53, P. aeruginosa (mucoid) 13, Klebsiella pneumoniae 19, and Moraxella catarrhalis 41.

Of 65 S. aureus strains, those with 2μgg/mL or less of MIC of oxacillin (methicillinsusceptible S. aureus: MSSA) and those with 4μgg/mL or more of MIC of oxacillin (methicillinresistant 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 0.063μgg/mL or less. Against MRSA, vancomycin and arbekacin showed the most potent activity and inhibited the growth of all the strains at 2μgg/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 0.063μgg/mL or less. Imipenem and faropenem also had a preferable activity and inhibited the growth of all the strains at 0.25 and 1μgg/mL, respectively. In contrast, there were high-resistant strains (MIC: over 128μgg/mL) for erythromycin (38.2%) and clindamycin (18.0%). Against H. influenzae, levofloxacin showed the most potent activity and its MIC₉₀ was 0.063μgg/mL or less. Meropenem showed the most potent activity against P. aeruginosa (mucoid) and its MIC₉₀ was 0.5μgg/mL. Against P. aeruginosa (non-mucoid), tobramycin had the most potent activity and its MIC₉₀ was 2μgg/mL. Against K. pneumoniae, cefozopran had the most potent activity and inhibited the growth of all the strains at 0.063μgg/mL or less. Also, all the antibacterial agents except ampicillin generally showed a potent activity against M. catarrhalis and the MIC₉₀ of them were 2μgg/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%.

From October 2008 to September 2009, we collected the specimen from 374 patients with lower respiratory tract infections in 15 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and patients’ characteristics. Of 423 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in infection, 421 strains were examined. The isolated bacteria were: Staphylococcus aureus 78, Streptococcus pneumoniae 78, Haemophilus influenzae 89, Pseudomonas aeruginosa (non-mucoid) 61, P. aeruginosa (mucoid) 19, Klebsiella pneumoniae 28, and Moraxella catarrhalis 32.

Of 78 S. aureus strains, those with 2μg/mL or less of MIC of oxacillin (methicillin susceptible S. aureus: MSSA) and those with 4μg/mL or more of MIC of oxacillin (methicillinresistant S. aureus: MRSA) were 34 (43.6%) and 44 (56.4%) strains, respectively. Against MSSA, imipenem had the most potent antibacterial activity and inhibited the growth of all strains at 0.063μg/mL or less. Against MRSA, vancomycin and arbekacin showed the potent activity and inhibited the growth of all the strains at 1 and 2μg/mL, respectively. Linezolid also showed the great activity and inhibited the growth of all the strains at 1μg/mL. Carbapenems and penems showed the most potent activities against S. pneumoniae and panipenem inhibited the growth of all the strains at 0.125μg/mL. Imipenem and faropenem also had a preferable activity and inhibited the growth of all the strains at 0.25 and 1μg/mL, respectively. In contrast, there were high-resistant strains (MIC: >128μg/mL) for erythromycin (43.6%) and clindamycin (19.2%). Against H. influenzae, levofloxacin showed the most potent activity and its MIC90 was 0.063μg/mL or less. Tobramycin showed the most potent activity against P. aeruginosa (mucoid) and its MIC90 was 2μ/mL. Against the non-mucoid type of P. aeruginosa, tobramycin and ciprofloxacin had the most potent activity and its MIC90 was 2μg/mL. Against K. pneumoniae, cefozopran had the most potent activity and inhibited the growth of all the strains at 0.063μg/mL or less. All the antibacterial agents except ampicillin generally showed a potent activity against M. catarrhalis and the MIC90 of them were 2μg/mL or less.

The majority number (57.7%) of the patients with respiratory infection were aged 70 years or older. Bacterial pneumonia and chronic bronchitis accounted for 40.9% and 32.9% of all the respiratory infection, respectively. The bacteria frequently isolated from the patients with bacterial pneumonia were S. aureus (20.5%), S. pneumoniae (21.1%), and H. influenzae (22.8%). S. aureus (21.7%) and P. aeruginosa (24.6%) also were frequently isolated from the patients with chronic bronchitis. The bacteria frequently isolated from the patients were S. pneumoniae (23.4%) and H. influenzae (25.1%) before administration of the antibacterial agents. The bacteria frequently isolated from the patients previously treated with cephems and macrolides were P. aeruginosa, and the isolation frequencies were 41.4% and 40.0%, respectively.

From October 2009 to September 2010, we collected the specimen from 432 patients with lower respiratory tract infections in 16 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and patients’ characteristics. All of 479 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in infection, were examined. The isolated bacteria were: Staphylococcus aureus 90, Streptococcus pneumoniae 74, Haemophilus influenzae 82, Pseudomonas aeruginosa (non-mucoid) 60, P. aeruginosa (mucoid) 31, Klebsiella pneumoniae 41, and Moraxella catarrhalis 34.

Of 90 S. aureus strains, those with 2μg/mL or less of MIC of oxacillin (methicillin susceptible S. aureus: MSSA) and those with 4μg/mL or more of MIC of oxacillin (methicillinresistant S. aureus: MRSA) were 43 (47.8%) and 47 (52.2%) strains, respectively. Against MSSA, imipenem had the most potent antibacterial activity and inhibited the growth of all strains at 0.063μg/mL or less. Against MRSA, vancomycin and arbekacin showed the potent activity and inhibited the growth of all the strains at 2 and 4μg/mL, respectively. Linezolid also showed the great activity and inhibited the growth of all the strains at 2μg/mL. Carbapenems and penems showed the most potent activities against S. pneumoniae and panipenem inhibited the growth of all the strains at 0.125μg/mL. Imipenem and faropenem also had a preferable activity and inhibited the growth of all the strains at 0.25 and 0.5μg/mL, respectively. In contrast, there were high-resistant strains (MIC: >128μg/mL) for erythromycin (51.4%) and clindamycin (35.1%). Against H. influenzae, levofloxacin showed the most potent activity and its MIC₉₀ was 0.063μg/mL or less. Meropenem showed the most potent activity against P. aeruginosa (mucoid) and its MIC₉₀ was 1μg/mL. Against the non-mucoid type of P. aeruginosa, tobramycin had the most potent activity and its MIC₉₀ was 2μg/mL. Against K. pneumoniae, cefozopran had the most potent activity and inhibited the growth of all the strains at 0.125μg/mL or less. All the antibacterial agents except ampicillin generally showed a potent activity against M. catarrhalis and the MIC₉₀ of them were 2μg/mL or less.

The majority number (60.0%) of the patients with respiratory infection was aged 70 years or older. Bacterial pneumonia and chronic bronchitis accounted for 48.8% and 31.7% of all the respiratory infection, respectively. The bacteria frequently isolated from the patients with bacterial pneumonia were S. aureus (21.5%), S. pneumoniae (20.2%), and H. influenzae (16.7%). S. aureus (21.9%) and P. aeruginosa (20.0%) also were frequently isolated from the patients with chronic bronchitis. The bacteria frequently isolated from the patients were S. pneumoniae (21.5%) and H. influenzae (20.5%) before administration of the antibacterial agents. The bacteria frequently isolated from the patients previously treated with cephems and macrolides were P. aeruginosa, and the isolation frequencies were 28.6% and 47.2%, respectively.