From October 2000 to September 2001, we collected the specimen from 410 patients with lower
respiratory tract infections in 16 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various
anti-bacterial agents and
antibiotics and patients' characteristics. Of 499 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in
inflammation, 493 strains were investigated. The breakdown of the isolated bacteria were: Staphylococcus aureus 78, Streptococcus pneumoniae 73, Haemophilus infiuenzae 99, Pseudomonas aeruginosa (non-mucoid) 64, P. aeruginosa (mucoid) 14, Klebsiella pneumoniae 25, Moraxella subgenus Branhamella catarrhalis 21, etc. Of 78 S. aureus strains, those with 4 micrograms/ml or more of MIC of
oxacillin (methicillin-resistant S. aureus: MRSA) occupied 53.8%.
Vancomycin and
arbekacin had the most potent activities against MRSA as observed in 1999. The frequency of S. pneumoniae exhibiting low sensitivity to
penicillin (
penicillin-intermediate S. pneumoniae: PISP +
penicillin-resistant S. pneumoniae: PRSP) was 38.4% being consistent with that in 1999 (34.7%). PRSP accounted for 11.0% of the total, being more than that in 1999 (3.0%).
Carbapenems had strong activities against S. pneumoniae. Especially,
panipenem inhibited the growth of all 73 strains at 0.125 microgram/ml. Generally, all drugs had strong activities against H. influenzae with MIC80s of 8 micrograms/ml or less. The drug that had the strongest activity against H. infiuenzae was
levofloxacin, which inhibited the growth of 94 of the 99 strains at 0.063 microgram/ml.
Tobramycin had a strong activity against P. aeruginosa (both mucoid and non-mucoid) with MIC80 of 1 microgram/ml. The mucoid strain was little isolated (14 strains) but the susceptibilities to all drugs were better than the non-mucoid strain. K. pneumoniae showed good susceptibilities to all drugs except
ampicillin and the MIC80S were 2 micrograms/ml or less. Particularly,
cefpirome,
cefozopran, and
levofloxacin had strong bactericidal activities against K. pneumoniae with MIC80s of 0.125 microgram/ml, and
cefotiam, second-generation cephems, also had a favorable activity being MIC80 of 0.25 microgram/ml. Also, all drugs generally had strong activities against M. (B.) catarrhalis. MIC80s of all drugs were 2 micrograms/ml or less. The drug having the strongest activity was
imipenem and
levofloxacin inhibiting all 21 strains at 0.063 microgram/ml. Most of the patients with respiratory
infection were aged 70 years or older, accounting for approximately a half of the total (44.4%). As for the incidence by the diseases,
bacterial pneumonia and
chronic bronchitis were the highest, being noted in 38.0% and 31.7% of all the patients, respectively. The bacteria frequently isolated from the patients with
bacterial pneumonia were S. aureus (18.3%) and S. pneumoniae (16.1%). In contrast, H. infiuenzae (20.4%) and P. aeruginosa (both mucoid and non-mucoid: 16.7%) were frequently isolated from the patients with
chronic bronchitis. Before the drug administration, the bacteria frequently isolated from all the patients were S. pneumoniae (24.3%) and H. infiuenzae (26.7%). The frequency of isolated S. pneumoniae tended to decrease with the increase in the number of administration days while that of isolated H. infiuenzae did not. The frequency of isolated P. aeruginosa tended to increase with the duration of administration. The isolated bacteria were comparable between the patients already treated with
penicillins and cephems. In the patients treated with
aminoglycosides,
macrolides, and
quinolones, P. aeruginosa was most frequently isolated (33.3 to 40.0%).