Resarch groups were formed in 21 institutions nationwide to investigate carbapenem resistance. The activities of various antibacterial agents, principally carbapenems were tested against clinical isolates collected from these institutions. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) of 17 antibacterial agents for 1,282strains of 11 bacterial species isolated at all institutions between October and December 1995.
The results were as follows:
1. Carbapenems exhibited strong antibacterial activities against MSSA andStreptococcus pneumoniae.Their activities againstEnterococcus faecalis were comparable to that of ABPC. Carbapenems showed low activities against MRSA.
2. OFLX exhibited the greatest antibacterial activity againstHaemophilus influenzae, followed by MEPM. The antibacterial activities of the other carbapenems were comparable to those of FMOX and CTM.
3. The carbapenems showed high activities againstEscherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, andBacteroides fragilis group. Their activities were greater than that exhibited by other β-lactam antibacterial agents. The carbapenems also exhibited greater antibacterial activities againstSerratia marcescens than the other β-lactam antibacterial agents, but some resistant strains were detected.
4. The antibacterial activities of carbapenems againstPseudomonas aeruginosa were comparable to those of CAZ, AZT, AMK.

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The frequencies of isolation and susceptibilities to antimicrobial agents were investigated on 680 bacterial strains isolated from patients with urinary tract infections (UTIs) in 10 hospitals during the period of June 1996 to May 1997. Of the above bacterial isolates, Gram-positive bacteria accounted for 30.4% and a majority of them were Enterococcus faecalis. Gram-negative bacteria accounted for 69.6% and most of them were Escherichia coli.
Susceptibilities of several isolated bacteria to antimicrobial agents were as followed;
1.Enterococcus faecalis
Ampicillin (ABPC) showed the highest activity against E. faecalis isolated from patients with UTIs.Its MIC₉₀ was 1 μg/ml. Imipenem (IPM) and vancomycin (VCM) were also active with the MIC₉₀s of 2,μg/ml. The others had low activities with the MIC₉₀s of 16 μg/ml or above.
2.Staphylococcus aureus including MRSA
Arbekacin (ABK) and VCM showed the highest activities against both S. aureus and MRSA isolated from patients with UTIs. The MIC₉₀s of them were 1 or 2 μg/ml. The others except minocycline (MINO) had low activities with the MIC₉₀s of 32,μg/ml or above.
3.Staphylococcus epidermidis
ABK and VCM showed the strongest activities against S. epidermidis isolated from patients with UTIs. The MICs for all strains were equal to or lower than 2 μg/ml. Cefazolin (CEZ), cefotiam (CTM) and cefozopran (CZOP) were also active with the MIC₉₀s of 4 μg/ml. Compared with antimicrobial activities of cephems in 1995, the MIC₉₀s of them had changed into a better state. They ranged from 4 μg/ml to 16 μg/ml in 1996.
4.Streptococcus agalactiae
All drugs except MINO were active against S. agalactiae. ABPC, CZOP, IPM, and clarithromycin (CAM) showed the highest activities. The MICs for all strains were equal to or lower than 0.125 μg/ml. Tosufloxacin (TFLX) and VCM were also active with the MIC₉₀s of 0.5 μg/ml.
5.Citrobacter freundii
Gentamicin (GM) showed the highest activity against C. freundii isolated from patients with UTIs. Its MIC₉₀ was 0.5,μg/ml. IPM and amikacin (AMK) were also active with the MIC₉₀s of 1μg/ml and 2μg/ml, respectively. Cefpirome (CPR) and CZOP were also active with the MIC₉₀s of 8 gg/ml. The MIC₉₀s of the others were 16 μg/ml or above.
6.Enterobacter cloacae
IPM showed the highest activity against E. cloacae. The MICs for all strains were equal to or lower than 0.5μg/ml. The MIC₉₀s of ciprofloxacin (CPFX) and TFLX were 1μg/ml, the MIC₉₀ of AMK was 2 μg/ml, the MIC₉₀s of CZOP, GM and ofloxacin (OFLX) were 4μg/ml. The MIC50s of cephems except CEZ, cefmetazole (CMZ) and cefaclor (CCL) had changed into a better state in 1996, compared with those in 1995.
7.Escherichia coli
All drugs except penicillins and MINO were active against E. coli. Particularly CPR, CZOP and IPM showed the highest activities against E. coli. The MIC₉₀s of them were 0.125μg/ml or below. Among E. coli strains, those with low susceptibilities to cephems except CEZ, cefoperazone (CPZ), latamoxef (LMOX) and CCL have increased in 1996, compared with those in 1995.
8.Klebsiella pneumoniae
K. pneumoniae was susceptible to all drugs except penicillins, with the MIC₉₀s of 2 μg/ml or below. CPR had the strongest activity, the MICs for all strains were equal to or lower than 0.25μg/ml. Flomoxef (FMOX), cefixime (CFIX), CZOP and carumonam (CRMN) were also active with the MIC₉₀s of 0.125 μg/ml or below.
9.Pseudomonas aeruginosa
All drugs except quinolones were not so active against P.aeruginosa with the MIC₉₀s were 32μg/ml or above.

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Clinical background was investigated on patients with urinary tract infections (UTIs) from whom 752 bacterial strains were isolated in 10 hospitals during the period from June, 1996 through May, 1997.
1. Distribution of age and sex of patients and type of infections
Among males, those with ages 40 years or older were more frequent, the higher the ages of them. Among females, those with ages in the 60's were the most frequent (24.6%), and those with ages in the 20's, 40's and 50's were about 13%. With regard to type of infections, more than a half of infections among males with ages 30 years or older were of complicated types, but most of infections among females were of uncomplicated types, especially among females of ages less than 60 years.
2. Ages of patients and types of pathogens
The higher the ages of patients, the lesser became the isolation frequencies of Escherichia coli, but the higher were those of Pseudomonas aeruginosa and Klebsiella spp.
3. Effect of antibiotic use on isolation frequencies of pathogens
Use of antibiotics decreased pathogens isolated from patients with uncomplicated UTIs drastically (231 isolates before antibiotics compared to 60 after). Even isolated pathogens from patients with complicated UTIs decreased drastically with the use of antibiotics when indwelling catheters were not in use (193 isolates before antibiotics compared to 75 after), but when indwelling catheters were in use, antibiotics apparently failed to decrease the isolation frequency.
4. Surgical procedures and types of causative organisms for UTIs
From cases of uncomplicated UTIs, E. coli was the most frequently isolated, followed by Enterococcus faecalis and Klebsiella spp. E. coli was the most frequently isolated organism from complicated UTIs without indwelling catheters. When a surgical procedures were not done, E. coli was isolated most frequently.From cases of complicated UTIs with indwelling catheters, P.aeruginosa, E. coli and E. faecalis were the organisms that were mainly isolated, with isolation frequencies of 23.2%, 15.2%, 12.2%, respectively. When no surgical procedures were used, isolation frequencies of P.aeruginosa, E. faecalis and Enterobacter spp. were 17.2%, 13.8%, 13.8%, respectively.

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Antibacterial activity of clindamycin against Propionibacterium acnes (P. acnes) was evalua ted in comparison with nadifloxacin in vitro. Using a burned-infected mouse model, topical application of 1% gel form of clindamycin phosphate on P.acnes was also evaluated in in vivo.
(1) The MIC of clindamycin measured by agar dilution metho d was 0.02μg/ml, and this value was smaller than that of nadifloxacin (0.3μg/ml).
(2) At concentrations of 1-, 2-and 4-times the MIC clindamycin demonstrated bacteriostatic activity on P.acnes and showed bactericidal activity at 5-times the MIC. Nadifloxacin showed bacteriostatic activity at one half the MIC and bactericidal activity at the MIC.
(3) Against acquired resistant strains of P.acnes, the highest concentrations of clindamycin and nadifloxacin that did not inhibit growth of the organism increased 5-fold higher than those against sen sitive strain during 25 successive cultures in vitro. Therefore, the resistance of P. acnes was found to be emerged at almost the same ratio against both agents.
(4) The chemotherapeutic effects of 1% gel form of clindamycin phosphate and 1% cream of nadifloxacin were evaluated for given subcutaneously to infected P.acnes at the burned site in mice. The topical application of either agents showed a significant reduction of number of bacteria and this result predicted clinical efficacy of topical application of clindamycin.

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