We evaluated the antibacterial activity of faropenem against penicillin-susceptible Streptococcus pneumoniae (PSSP) and penicillin-resistant S. pneumoniae (PRSP). It was shown that the minimum inhibitoryconcentrations against 90% of the clinically isolated strains (MIC₉₀) of faropenem, penicillin G, cefaclor, cefcapene, and cefditoren against PSSP were 0.032, 0.063, 2, 0.25, and 0.125, μg/ml, respectivily. While thoseagainst PRSP were 0.5, 2, >128, 1, and 1μg/ml, respectively. Furthermore, we evaluated the bactericidal activity, at the level of 1/4, 1, and 4 MIC, of faropenem and the above four reference antibacterial agents against PSSPand PRSP. Against PSSP No.127, a sensitive strain to both penicillin G and cefcapene, faropenem showedalmost the same bactericidal activity as those of reference agents. Against PSSP No.108, a penicillin-susceptibleand cephem-resistant strain, and PRSP No.57, a resistant strain to both of penicillin and cephem, faropenem of1 MIC showed bactericidal activity, but reference agents needed 4 MIC to show bactericidal activity.

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In this study, the in vitro activity of levofloxacin (LVFX) against 1,020 fresh bacterial clinical isolates wascompared with the activities of a range of ofloxacin, ciprofloxacin (CPFX), ampicillin (ABPC), cefaclor, cefpodoxime, methicillin and benzylpenicillin. The clinical isolates except Vibrio cholerae were collected in Japan during 1998 from patients with infectious diseases. MICs were determined using the agar dilutionmethod according to the recommendations by the Japan Society of Chemotherapy. Some isolates of methicillinresistant Staphylococcus aureus (MRSA) and coagulase negative Staphylococcus were resistant tofluoroquinolones, but the MIC₅₀ of LVFX against MRSA was 6.25 μg/ml. LVFX was the most active against MRSAamong the antibiotics tested. Most of Staphylococcus epidermidis strains were susceptible to the fluoroquinolones.LVFX showed greater activity against all streptococci strains compared with fluoroquinolones tested. In particular, all Streptococcus pneumoniae strains including PRSP were susceptible to LVFX at ≤1.56μg/ml. AmongEnterococcus, ABPC showed superior activity against <>Enterococcus faecalis but many isolates of Enterococcusspecies were resistant to ABPC. LVFX was more active against to these Enterococcus species comparedwith other fluoroquinolones.
On the other hand, LVFX and CPFX showed similar activity against isolates of Enterobacteriaceae. CPFXhad an MIC_50/90 of 0.20, 0.39 3μg/ml and LVFX showed an MIC_50/90 of 0.78, 1.56 μg/ml against Pseudomonasaeruginosa. LVFX (MIC_50/90 0.10, 0.20 μg/ml) was more active against Acinetobacter species than CPFX (MIC_50/90.10, 0.39 μg/ml).Haemophilus influenzae, Branhamella (Moraxella) catarrhalis and V. cholerae were inhibitedby low concentration of the fluoroquinolones tested. The MIC₉₀ of LVFX and CPFX were≤0.10 μg/ml againstabove three species. Some isolates of Neisseria gonorrhoeae and Campylobacter species were moderatelyresistant to the fluoroquinolones tested but the MIC₅₀ of LVFX and CPFX were ≤0.39 μg/ml. Among anaerobes, Propionibacterium acnes was more susceptible than Peptostreptococcus species, and the MIC₉₀ of β-lactamsand fluoroquinolones tested were≤0.78 μg/ml.
In conclusion, this study, performed on large number of strains, confirmed an excellent and wide spectrumantibacterial activity of LVFX compared with the fluoroquinolones and β-lactams tested. And our results suggest that LVFX may be useful in the treatment of various bacterial infections.

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MICs of various β-lactam antibiotics by themselves and in combination with β-lactamase inhibitor (clavulanic acid) against extended spectrum β-lactamase (ESBL) producing strains of Escherichia coli and Klebsiellapneumoniae which were isolated from clinical materials were investigated. Furthermore, based on theresults obtained, a procedure to detect ESBL producing strains was proposed.
The MICs of β-lactam antibiotics against β-lactamase producing strains were investigated. At first, β -lactamase was investigated by the drug sensitivity pattern (MIC) to, β-lactam antibiotics and by the substrateprofiles of β-lactamase extracted from the transconjugant of E. coli K-12 strains. After that, we classified theβ -lactamase producing gene by PCR method. Furthermore, a proposal was made for anantibiotic to be used in theconfirmation of mixed type β-lactamase. The data obtained by the above investigations were compiled and usedto determine the limit concentration of each β-lactam against β-lactamase producing strains including ESBL. Byusing β-lactam antibiotics at the following concentrations, it is considered possible to classify β-lactamase;ampicillin (64μg/ml), ampicillin/clavulanic acid (32/5μg/ml), piperacillin (64, μg/ml), cefotaxime (1μg/ml), cefpodoxime (2μg/ml), ceftazidime (1μg/ml), cefmetazole (4μg/ml), cefminox (2μg/ml), cefepime (0.5μg/ml), aztreonam (1μg/ml) and imipeneme (1μg/ml). This method may be used as a reference in investigating the prevalence of β-lactam resistant isolates by ESBL producing E. coli and K. pneumoniae.

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