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 2μg/mL or less of MIC of oxacillin (methicillin-sensitive S. aureus: MSSA) and those with 4μg/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 0.063μg/mL. Against MRSA, vancomycin showed the most potent activity and inhibited the growth of all the strains at 1μg/mL. Arbekacin (ABK) also showed the potent activity and its MIC₉₀ was 2μg/mL. Carbapenems showed the most potent activities against S. pneumoniae and inhibited the growth of all the strains at 0.25-0.5μg/mL. Cefozopran (CZOP) also had a preferable activity (MIC₉₀: 1μg/mL) and inhibited the growth of all the strains at 2μg/mL. In contrast, there were high-resistant strains (MIC: 128μg/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 0.125μg/mL.Meropenem showed the most potent activity against P. aeruginosa (mucoid) and inhibited the growth of all the strains at 2μg/mL. Against P. aeruginosa (non-mucoid), amikacin (AMK) had the most potent activity and its MIC₉₀ was 4μg/mL. The activity of CZOP against the non-mucoid type also was preferable and its MIC₉₀ was 8μg/mL. Against K. pneumoniae, CZOP, cefmenoxime, cefpirome, flomoxef were the most potent activity and inhibited the growth of all the strains at 0.063μg/mL. Also, all the agents generally showed a potent activity against M.(B.) catarrhalis and the MIC₉₀ of them were 4μg/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%.

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We analyzed Pseudomonas aeruginosa isolates in Gifu prefecture between September and October 2004. We conducted antimicrobial susceptibility test for 266 strains isolated from 8 medical institutes and 1 clinical laboratory, based on broth microdilution method. The MIC₅₀ and MIC₉₀ of piperacillin, amikacin, imipenem, and ciprofloxacin were 4 and 64, 4 and 8, 1 and 16, 0.25 and 8μg/mL, respectively. The strains isolated from urine had higher MIC level in comparison with from sputum, which was remarkable in penicillins, cephalosporins and fluoroquinolones. We isolated 7 strains of multi-drug resistant Pseudomonas aeruginosa (MDRP), in which 3 strains showed under 16μg/mL in MIC against anti-MRSA (methicillin-resistant Staphylococcus aureus) drug arbekacin. Continuous surveillance would be needed for antimicrobial resistance on P. aeruginosa in Gifu prefecture.

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There have not been sufficient clinical studies based on pharmacokinetics /pharmacodynamics (PK/PD) theory, on which many clinical doctors have recently focused. To consider the optimized administration method based on PK/PD theory for gatifloxacin (GFLX), which was one of the oral fluoroquinolone antibacterial, we investigated clinical efficacies and adverse events for pelvic inflammatory disease (PID) in giving GFLX daily 400mg divided twice a day or four times a day. The number of leukocyte and the value of CRP were significantly reduced by chemotherapy in twice a day group, compared with four times a day group. We were able to measure the blood level in 4 cases. The AUC/MIC values for presumption causative bacteria (causative bacteria in both cases: Escherichia coli) in cured patients were 142.28 and 280.16, however, in therapy-failed patients, the AUC/MIC value to presumption causative bacterium were 4.10 (causative bacteria: Prevotella bivia) and 4.35 (causative bacteria: Pseudomonas aeruginosa). These results suggested the importance of the therapeutic method based on PK/PD theory.

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Fifty isolates of Streptococcus pneumoniae and 42 isolates of Haemophilus influenzae were isolated from the blood of children admitted to pediatric wards of hospitals in subprefucture between January 1998 and December 2005. The susceptibilities were measured by a microbroth dilution method using a standard broth and a broth containing 4.5% albumin. Against S. pneumoniae, penicillin G, ampicillin, cefotaxime, ceftriaxone, panipenem, meropenem, vancomycin, cefditoren, cefcapene, cefteram, faropenem and tebipenem were used and against H. influenzae, ampicillin, piperacillin, cefotaxime, ceftriaxone, panipenem, meropenem, clavulanic acid/ amoxicillin, cefditoren, cefcapene, cefteram, faropenem and tebipenem were used. Against S. pneumoniae, tebipenem was the highest antimicrobial activity in oral antibiotics (MIC₉₀;<0.06μg/ml) and panipenem showed the highest activity for intravenous antibiotics (MIC₉₀;<0.12μg/ml). Against H. influenzae, cefditoren was the highest activity for oral antibiotics (MIC₉₀;<0.06μg/ml) and meropenem showed the highest activity for intravenous antibiotics (MIC₉₀;<0.06μg/ml). The MIC90S measured by albumin containing broth were higher than those measured by standard broth. Protein binding rates of ceftriaxone, cefditoren, and faropenem were greater than 90%, and the MIC₉₀ of these antibiotics measured by albumin addition methods were over 4-fold higher than those measured by standard methods.

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