Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (2004)

From October 2004 to September 2005, we collected the specimen from 319 patients with lower respiratory tract infections in 12 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and patients' characteristics. Of 383 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in inflammation, 381 strains were examined. The breakdown of the isolated bacteria were: Staphylococcus aureus 87, Streptococcus pneumoniae 80, Haemophilus influenzae 78, Pseudomonas aeruginosa (non-mucoid) 35, P. aeruginosa (mucoid) 9, Klebsiella pneumoniae 15, Moraxella subgenus Branhamella catarrhalis 30, etc. Of 87 S. aureus strains, those with 2 μg/mL or less of MIC of oxacillin (methicillin-sensitive S. aureus: MSSA) and those with 4 μg/mL or more of MIC of oxacillin (methicillin-resistant S. aureus: MRSA) were 40 (46.0%) and 47 (54.0%) strains, respectively. Against MSSA, imipenem had the most potent antibacterial activity and inhibited the growth of all the strains at 0.063 μg/mL. Against MRSA, vancomycin showed the most potent activity and inhibited the growth of all the strains at 1 μg/mL. Arbekacin (ABK) also showed the potent activity and its MIC ₉₀ was 2 μg/mL. Carbapenems showed the most potent activities against S. pneumoniae and inhibited the growth of all the strains at 0.25-0.5 μg/mL. Cefozopran (CZOP) also had a preferable activity (MIC ₉₀: 1 μg/ mL) and inhibited the growth of all the strains at 2 μg/mL. In contrast, there were high-resistant strains (MIC: 128 μg/mL or more) for ABK (2.5%), erythromycin (37.5%), and clindamycin (38.8%). Against H. influenzae, levofloxacin showed the most potent activity and inhibited the growth of all the strains at 0.125 μg/mL. Meropenem showed the most potent activity against P. aeruginosa (mucoid) and inhibited the growth of all the strains at 2 μg/mL. Against P. aeruginosa (non-mucoid), amikacin (AMK) had the most potent activity and its MIC ₉₀ was 4 μg/mL. The activity of CZOP against the non-mucoid type also was preferable and its MIC ₉₀ was 8 μg/mL. Against K. pneumoniae, CZOP, cefmenoxime, cefbirome, flomoxef were the most potent activity and inhibited the growth of all the strains at 0.063 μg/mL. Also, all the agents generally showed a potent activity against M. (B.) catarrhalis and the MIC ₉₀ of them were 4 μg/mL or less. The approximately half the number (57.0%) of the patients with respiratory infection were aged 70 years or older. Bacterial pneumonia and chronic bronchitis accounted for 50.8% and 23.8% of all the respiratory infection, respectively. The bacteria frequently isolated from the patients with bacterial pneumonia were S. aureus (21.6%), S. pneumoniae (24.7%) and H. influenzae (20.1%). S. aureus (20.9%), S. pneumoniae (16.1%), and H. influenzae (16.1%) also were relatively frequently isolated from the patients with chronic bronchitis. Before the drug administration, the bacteria frequently isolated from the patients were S. pneumoniae (22.3%) and H. influenzae (25.1%). The bacteria relatively frequently isolated from the patients treated with macrolides were P. aeruginosa and the isolation frequency was 43.5%.