Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (2002)

From October 2002 to September 2003, we collected the specimen from 476 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. Of 584 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in inflammation, 578 strains were examined. The breakdown of the isolated bacteria were: Staphylococcus aureus 77, Streptococcus pneumoniae 103, Haemophilus influenzae 95, Pseudomonas aeruginosa (non-mucoid) 61, P. aeruginosa (mucoid) 23, Klebsiella pneumoniae 36, Moraxella subgenus Branhamella catarrhalis 29, etc. Of 77 S. aureus strains, those with 2 μg/ml or less of MIC of oxacillin (MPIPC) [methicillin-susceptible S. aureus: MSSA] was 34 strains (44.2%) and those with 4 μg/ml or more of MIC of oxacillin (methicillin-resistant S. aureus: MRSA) was 43 strains (55.8%). Against MSSA, imipenem (IPM) and minocycline (MINO) had the most potent antibacterial activity and inhibited the growth of all the strains at 0.25 μg/ml. Although clindamycin (CLDM) and aminoglycosides also had the potent activity, the resistant strains against those agents were detected. Cefotiam (CTM) inhibited the growth of all the strains at 1 μg/ml without the low sensitive strains. Against MRSA, vancomycin (VCM) showed the most potent activity and inhibited the growth of all the strains at 2 μg/ml. Arbekacin (ABK) also showed the relatively potent activity and inhibited the growth of all the strains at 4 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, the resistant strains for cefaclor (CCL), erythromycin (EM), CLDM, and tetracycline (TC) were detected in 50.5%, 76.7%, 50.5%, and 80.6% of all the strains, respectively. Against H. influenzae, LVFX showed the most potent activity and inhibited the growth of 92 of all the strains (96.8%) at 0.063 μg/ml. Tobramycin (TOB) showed the most potent activity against P. aeruginosa (both mucoid and non-mucoid) and inhibited the growth of all the strains at 2 μg/ml. The antibacterial activity of CZOP was good and its MIC ₉₀ against mucoid and non-mucoid strains was 8 and 16 μg/ml, respectively. CZOP and cefpirome (CPR) were the most potent against K. pneumoniae with 0.125 μg/ml of MIC ₉₀. Also, all the agents generally showed potent activities against M. (B.) catarrhalis and the MIC ₉₀ of all drugs were 4 μg/ml or less. The approximately half the number (47.5%) of the patients with respiratory infection were aged 70 years or older. As for the incidence by the diseases, bacterial pneumonia and chronic bronchitis were the highest, being noted in 35.7 and 33.8% of all the patients, respectively. The bacteria frequently isolated from the patients with bacterial pneumonia were S. pneumoniae (22.6%). In contrast, S. aureus (16.6%) and P. aeruginosa (13.7%) were relatively frequently isolated from the patients with chronic bronchitis. Before the drug administration, the bacteria frequently isolated from all the patients were H. influenzae (24.5%) and S. pneumoniae (24.2%). In comparison of the isolated bacteria by pretreatment agents, P. aeruginosa was relatively frequently isolated from the patients pretreated with cephems or macrolides and H. influenzae was relatively frequently isolated from the patients pretreated with penicillins.