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Group A streptococcus is a bacterium that resides in the throat and skin and causes respiratory infection and occasionally glomerulonephritis and rheumatic fever. Streptolysin O (SLO) produced by Streptococcus pyogenes (S. pyogenes) binds to the cell membrane, particularly to that of white and red blood cells, and is toxic to the cells and tissue. In this study, we evaluated the inhibitory activity of water-soluble polyphenols in olives (Olea europaea) against SLO-induced hemolysis. Hydroxytyrosol inhibited SLO-induced hemolytic activity, and the amount required for 50% inhibition of hemolysis was 1.30 µg. These findings suggest that the water-soluble polyphenols contained in olives have inhibitory activity against SLO-induced hemolysis.

Background/Purpose Whether absorption of verotoxin (VT) 2 from the intestine in mice is inhibited by administration bovine immune colostral antibody against VT2 was investigated. Methods Three-week-old mice were administered VT2 solution at 477.8 ng/mL or 955.6 ng/mL, and bovine immune colostral antibody against VT2 was then administered three times. Whey without antibody against VT2 was administered to control mice. Serum levels of VT2 were measured by fluorescence enzyme immunoassay. Results Serum levels of VT2 in mice administered VT2 solution at 477.8 ng/mL and bovine immune colostral antibody against VT2 scarcely changed. By contrast, serum levels of VT2 in control mice increased and peaked 12 hours after administration. Peak values were 15.4 ± 5.04 ng/mL. Furthermore, serum levels of VT2 at 12 hours and 16 hours in control mice were significantly higher than in mice administered bovine colostral antibody against VT2. Serum levels of VT2 in mice administered antibody at 955.6 ng/mL showed no significant differences between repeated administration of bovine immune colostral antibody and controls. Conclusion These results suggest that absorption of VT2 from the intestine was inhibited by repeated administration of bovine immune colostral antibody against VT2 at early stages of Escherichia coli O157:H7 infection, whereas VT2 in the intestine remained at low levels.

Drug susceptibility testing was carried out using 14 antibiotics in order to identify trends in the antibiotic tolerance of 142 strains of Enterobacteriaceae isolated from horsemeat commercially available for raw consumption (basashi). A comparison of the sensitivity to the 14 antibiotics using the 90% MIC (minimum inhibitory concentration) values (MIC90) showed the strongest tolerance to ampicillin (ABPC) at a concentration of > 128 μg/mL, followed by that to fosfomycin (FOM) at a concentration of 128 μg/mL. When the sensitivity to these antibiotics was examined for each individual genus of tested bacteria, Hafnia spp. exhibited relative tolerance to ceftazidime (CAZ) and ceftriaxone (CTRX) at a concentration of 4 μg/mL and 2 μg/mL, respectively, which was high in comparison to that observed for the other strains. Furthermore, Raoultella spp. and Serratia spp. were found to be highly resistant to tetracycline (TC) at a concentration of 128 μg/mL and 64 μg/mL, respectively. Of the 142 strains of test bacteria, 140 (98.6%) demonstrated resistance to ABPC, with the exception of Hafnia alvei and Klebsiella pneumonia. In addition, a total of eight strains (5.6%), seven Serratia marcescens strains and one Raoultella terrigena strain, were found to be resistant to TC. Furthermore, one strain of Citrobacter freundii exhibited resistance to nalidixic acid (NA), while another displayed resistance to ofloxacin (OFLX) (0.7% each), and one strain (0.7%) each of Enterobacter cloacae, Serratia marcescens and Citrobacter youngae demonstrated resistance to fosfomycin (FOM), streptomycin (SM) and kanamycin (KM), respectively. A single strain of C. freundii was found to be resistant to three antibiotics, ABPC, NA and OFLX. Resistance to two antibiotics was confirmed in 11 strains, including seven strains of S. marcescens and one strain of R. terrigena (a total of eight strains) resistant to ABPC and TC, and one strain each of C. youngae, S. marcescens and E. cloacae resistant to ABPC and KM, ABPC and SM, and ABPC and FOM, respectively. In addition, 128 strains were resistant to the single antibiotic of ABPC alone. Of the 140 strains demonstrating antibiotic resistance, 137 (97.9%) retained the conjugative R-plasmid transfer factor, excluding three strains of S. marcescens. All transfer factors were ABPC and retained by a high proportion of the bacterial groups, with one strain (100%) being resistant to three antibiotics, nine (81.8%) of the 11 strains being resistant to two antibiotics, and 127 (99.2%) of the 128 strains being resistant to a single antibiotic. In addition, we examined ESBL productivity in the 140 strains of bacteria demonstrating drug tolerance; however, no strains exhibited this characteristic. Therefore, further observation is required to ascertain trends in antibiotic-tolerant bacteria.

For a microbial ecological analysis, 20 strains of Legionella pneumophila isolated from both unchlorinated Noyu (unattended natural hot spring) samples and chlorinated hot spring bath water samples collected throughout Japan were subjected to a clustering analysis on the basis of a Pulsed-Field Gel Electrophoresis (PFGE) pattern analysis. The PFGE patterns obtained from 19 strains of L. pneumophila after digestion with SfiI were used to divide the strains into two groups (Groups A and B), although the similarity level was very low among the groups. Group A consisted of 8 strains, and all of these strains were isolated from hot spring bath water samples. Group B consisted of 11 strains, and all but two of these strains were isolated from Noyu samples. The chlorine resistance (99.9% CT values) of these isolates was experimentally confirmed, and we attempted to define the relationship between chlorine resistance and the geno-cluster. The average CT value of group A (8 strains from hot spring bath water) was 0.49 mg･min/l and the average of group B (9 strains from Noyu samples) was 0.29 mg･min/l. No remarkable differences in the CT values for the groups were found. A chlorine-sensitive Noyu strain (0.14 mg･min/l) and a chlorine-resistant strain (0.62 mg･min/l) from hot spring bath water were then compared to identify any differences in their lipid composition. There was no notable difference in the ratio of saturated to unsaturated fatty acids between the chlorine-sensitive and chlorine-resistant bacteria. However, the chlorine-sensitive and chlorine-resistant bacteria demonstrated differences in the relative percentages of cell wall and cell membrane fatty acids.

Strain K-20(T), a Gram-negative, nonmotile, nonspore-forming and strictly aerobic coccobacillus, which produces a pale pink pigment (R2A agar medium, 30℃, seven days) was isolated from a sample of biofilm obtained from a cooling tower in Tokyo, Japan. A phylogenetic analysis of the 16S rRNA partial gene sequences (1,439 bp) showed that the strain (accession number: AB297501) was related to Roseomonas frigidaquae CW67(T) and Roseomonas stagni HS-69(T) with 97.4% and 96.9% sequence similarity, respectively. Strain K-20(T) formed a distinct cluster with Roseomonas frigidaquae CW67(T) in the phylogenetic tree at a high bootstrap value (93%); however, distance was recognized between the strains. In addition, the DNA-DNA hybridization level between strain K-20(T) and Roseomonas frigidaquae JCM 15073(T) was 33%. The taxonomic data indicate that K-20(T) (=JCM 14634(T) =KCTC 32152(T)) should be classified in the genus Roseomonas as the type strain of a novel species, Roseomonas tokyonensis sp. nov.

Heterotrophic bacteria constituting the biofilm produced in a kitchen sink drain were analyzed, and the biofilm formation abilities and the hydrophobicity of the cell surface layer were measured for the isolates. When the biofilm sample was cultured at 36 degrees C and 25 degrees C for 7 days, there were about 10 times more colonies on oligotrophic R2A agar medium than on eutrophic BHI agar medium. From isolates from the biofilm sample, 13 bacterial species were detected. To examine the biofilm formation ability of these strains, we measured the absorbance (OD570) by crystal violet staining. The absorbance of Brevibacterium casei 7-R-36-1 was the highest (3.029). In the comparison of the absorbance values between genera, Brevibacterium spp. (4 strains) showed the highest absorbance (mean: 2.056), followed by K. pneumoniae (4 strains) with a mean of 1.111. Regarding the hydrophobicity of the isolates, the values ranged from 0.002 for P. nitroreducens (strain 1-B-36-2) to 0.096 for M. lacticum (strain 5-R-25-2). The hydrophobicity values were generally low, and the cell surface layer of all tested strains was highly hydrophilic. The diversity of species of bacteria in the biofilm sample produced in the kitchen sink drain was recognized, and all the isolates had biofilm formation abilities.

Forty-five strains of Pseudomonas aeruginosa isolated from cockroaches captured in hospitals were investigated with regard to their biofilm-forming ability and resistance to various disinfectants in various cellular states. The hydrophobicity value varied among the test strains from 0.001 to 0.241, and the mean +/- standard deviation (SD) was 0.101 +/- 0.074. The relative viscosity of the extracellular product was measured. All test strains produced a mucous substance, and the value was 1.05-1.30 (mean +/- SD: 1.11 +/- 0.06), showing that all test strains had a biofilm-forming ability. Bactericidal experiments were performed using 6 disinfectants: ethanol, Hibitane, Isojin, Osvan, Tego 51, and Welpas. When bacteria in suspension were exposed to the disinfectants for 1 min (suspension test), 5 of the 6 disinfectants excluding Tego 51 completely killed all test strains, showing high bactericidal effects. In contrast, when adherent bacteria were exposed to the disinfectants for 1 min (adhesion test), the killing rate by Welpas was 100%, but those by Isojin and ethanol were lower (88.9 and 60.0%, respectively), that by Osvan was only 4.4%, and no bacteria were killed by Hibitane or Tego 51. These findings showed that the bactericidal effects markedly decreased in the case of adherent P. aeruginosa.

Strain K-20, a Gram-negative, non-motile, non-spore-forming and strictly aerobic rod, which produces a pale pink pigment, was isolated from biofilm in a cooling tower in Tokyo, Japan. The taxonomic feature of the strain was studied using phenotypic tests and phylogenetic analysis. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain was related to Roseomonas gilardii subsp. rosea, Roseomonas gilardii subsp. gilardii, Roseomonas cervicalis and Roseomonas mucosa at 94.3-94.6 sequence similarities. Growth occurred at 25-40 C and pH 5.0-10.0, optimal at 35 C and pH 7.0. Growth did not occur in the presence ofor=2% NaCl. The API 20NE identification system gave a positive result for urease, L-arabinose, potassium gluconate, adipic acid, malic acid and trisodium citrate (API code number 0201465). The predominant fatty acids of strain K-20 were C18:1Delta11 (50.8%) and C16:1 (17.2%). Cells contained ubiquinone 10 (Q-10) as the major quinone and the G+C content was 72.0 mol%. Based on phenotypic, chemotaxonomic and phylogenetic data, it was assumed that strain K-20 (=JCM 14634) is a novel species of the genus Roseomonas.

To clarify the route and source of Vibrio vulnificus infection, we conducted molecular epidemiological investigation by DNA analysis of 355 environmental isolates (seawater-derived strain: 86, sea mud-derived strain:36, and oyster-derived strain: 233) and 65 human clinical isolates, for a total of 420 isolates, using pulse field gel electrophoresis (PFGE), with the following results. 1. When DNA was cleaved with 2 enzymes, Not I and Sfi I, and subjected to PFGE, Not I DNA interpretation was 76.9%, and Sfi I cleavage was 97.9%, showing that Sfi I was superior in cleaving DNA of this bacteria. 2. Sfi I-interpreted strains were subjected to PFGE and migration patterns were analyzed by UPGMA, but close classification was not possible because similarity was low, this infectious disease clearly originated from multiple rather than a single-clone. In this cluster, we concluded that this infectious disease was acquired through contact between the environment and human beings and viceversa. We identified an assortment of clinical isolates and environment-derived strains among more than 89% of strain groups tested, none of which could be expected to have the same origin. We conclued DNA analysis on these two types of restriction enzymes using PFGE, but were unable to classify test results in detail due to the proliferation of migration patterns and low degree of similarity.

We previously reported that certain constituents in brewed coffee exhibited antibacterial activities against a strain of Legionella pneumophila. The constituents showing antibacterial activities were included only in extracts cold with water or hot water. To determine the antibacterial substances in coffee extract, the extract was fractionated by HPLC using a UV/photodiode array detector. The optimum HPLC conditions for analysis were UV wavelength of 250 nm and eluents of methanol/acetic acid (10/90), pH 3.0. When several fractions separated by HPLC were investigated for antibacterial activities against L. pneumophila, it was found that three peak fractions exhibited strong antibacterial activities. Each product from these fractions was analyzed by NMR and LC-mass spectrometry, and the chemical structure of each was determined. It was shown that the antibacterial substances was were protocatechuic acid (3,4-dihydroxy benzoic acid), chlorogenic acid, and caffeic acid.

Minimum Inhibitory Concentration (MIC) of 4 new-quinolone antibacterial reagents and 4 macrolide antibiotics against periodontopathic bacteria 21 species 24 strains of standard strains including oral related bacteria and clinical isolated (1993-1999) 20 strains of Porphyromonas gingivalis, 7 strains of Actinobacillus actinomycetemcomitans were determined. Minocycline HCl was used as the comparative reagent. Macrolide showed moderate antibacterial activity against standard strains of oral related bacteria except Fusobacterium nucleatum. New-quinolone showed excellent activity against Eikenella corrodens and Actinobacillus actinomycetemcomitans. Concerning to the clinical isolated strains, Clarithromycin effected P. gingivalis (MIC90 0.1 microgram/ml) and Levofloxacin and Ciprofloxacin showed high-potency antibacterial activity against clinical isolated Actinobacillus actinomycetemcomitans (MIC90 0.013-0.025 microgram/ml).

A Shigella flexneri 2a strain, which did not respond clinically or in laboratory tests to treatment with new quinolone derivatives, was isolated for the first time in Japan from a patient admitted for diarrhea to a Tokyo hospital. The mechanism of resistance was examined by sequencing the quinolone resistance determining region (QRDR) of the gyrA (a quinolone target enzyme) gene and by comparing the active efflux mechanisms of two strains isolated from this patient (before hospitalization and after tosufloxacin treatment) and one strain isolated from a patient with secondary infection with that of the standard strain ATCC 29903. DNA sequencing revealed that two amino acid substitutions, namely, Ser (TCG)-83-->Leu (TTG) and Asp (GAC)-87-->Gly (GGC), had occurred in the gyrA of all 3 strains isolated from the patients. Examination of the accumulation of antibiotics in these 3 strains revealed that the strain isolated after tosufloxacin treatment had the highest resistance to tosufloxacin, and exhibited decreased accumulation of tosufloxacin in the bacterial cells discharged after 5 days of treatment with this antibiotic. However, accumulation was restored by addition of a proton-pump inhibitor. These results suggest that the strains isolated from the inpatient and the patient with secondary infection acquired resistance due to dual gyrA mutation induced by treatment with new quinolone antibiotics. Furthermore, in addition to this dual mutation, the active efflux mechanism also appears to be associated with resistance in bacteria that have been exposed to tosufloxacin.

In May 2012, strain HNN-6 (=JCM 18566) , a Gram-negative, non-spore-forming, motile and strictly aerobic rod, which produces a pale orange pigment, was isolated from a hot spring water sample obtained in Kagoshima, Japan, by a plating method using R2A medium at 30°C for 7 d. The 16S rRNA gene sequences (1,437bp) of this strain (accession number: AB731137) had a close similarity (99.1%) to Hydrotalea sandarakina AF-51T (JF739858) . Growth occurred at 25-45°C and pH 5.0-8.0, with optimal growth at 40°C and pH 6.0-7.0. Growth did not occur in the presence of ≧2% NaCl. The API 20NE identification system gave positive results for nitrate, aesculin, gelatin, 4-nitrophenyl-β-D-galactopyranoside, D-glucose, D-mannose, maltose and oxidase (API code number 1472204) . The dominant cellular fatty acids of strain HNN-6 were iso-C15:0 (32.6%) , iso-C17:0 3-OH (24.2%) and iso-C16:0 (8.4%) . The guanine-plus-cytosine (G+C) content of DNA was 36.2 mol%. This article is the first report to describe the characteristics of an orange-pigmented bacterium isolated from a hot spring water sample in Japan.

Prulifloxacin (PUFX), a new quinolone antimicrobial agent, was administered to a total of 122 patients and carriers to investigate its clinical efficacy, safety and usefulness in infectious enteritis (bacillary dysentery, enteritis caused by Salmonella spp. and enteropathogenic E. coli, cholera and so on). In addition, the minimum inhibitory concentration (MIC) of UFX (active compound) was determined against each clinical isolate, and compared with that of ciprofloxacin (CPFX), ofloxacin (OFLX), tosufloxacin (TFLX) and nalidixic acid (NA). The correlation between the concentration of UFX in feces and the change of the fecal microflora were also investigated when PUFX was administered to the patients with acute infectious enteritis. A daily dose of 400 mg of PUFX was administered orally in two divided doses (morning and evening) for 5 days, with the exception of 7 days administration against salmonella enteritis and 3 days administration against cholera. 84 cases were adapted for evaluating the usefulness. The clinical efficacy was 100% in all the enteritis except salmonella enteritis, in which it was 88.9% (8/9 cases). On the bacteriological efficacy, the elimination rate was 100% in all isolates except Salmonella spp., in which it was 75.0% (12/16 cases). As for the adverse effect, uriticaria in moderate degree was observed in 1 (0.9%) of 109 cases. Abnormal changes in laboratory findings were seen in 3 (3.0%) of 100 cases, consisting of 1 with eosinophilia and 2 with elevated S-GPT, although they were all slight in degree. The usefulness rate was 65.5% (55/84 cases) for "very useful" and 95.2% (80/84 cases) for "very useful" and "useful". MIC90 of UFX against Shigella spp., Salmonella spp., E. coli and V. cholerae, was 0.025, 0.05, 0.025 and 0.05 microgram/ml, respectively. These values were the same as those of CPFX and TFLX, and superior to OFLX and NA. UFX concentrations in feces followed by administration of PUFX in 3 cases with acute infectious enteritis were higher than that of MIC90 of UFX against Shigella spp., Salmonella spp., E. coli and V. cholerae. The changes of the fecal microflora, which influence the efficacy and safety of PUFX, were not observed.

A clinical study was carried out on pazufloxacin (PZFX) in 137 patients including shigellosis, Salmonella enteritis, enteropathogenic Esherichia coli enteritis and cholera, and carriers of these pathogens. Antibacterial activity of PZFX against clinical isolates, fecal concentration of PZFX and effects of PZFX on fecal microflora were also investigated. The overall clinical efficacy rate was 97.2%. The bacteriological efficacy rates were 98.2% against Shigella spp., 81.8% against Salmonella spp., 50% against Vibrio cholerae O1, and 100% against E. coli, V. parahaemolyticus, Aeronomas spp., Plesionomas shigelloides and V. cholerae non-O1, respectively. Side effect (epigastralgia) was observed in 1 of 130 cases (0.8%). The rate of abnormal laboratory findings was 11.2% (11/98). These were mainly elevation of GOT and/or GPT and increased eosinophils. The clinical usefulness rate was 95.2%. The MIC90 values of PZFX against Shigella spp., Salmonella spp. and E. coli were 0.025, 0.025 and 0.025 micrograms/ml, respectively. The results of fecal drug concentration and the effects on fecal microflora in one patient were compatible with those obtained in healthy volunteers.

The efficacy, safety and usefulness of balofloxacin (BLFX) for patients with acute infectious enteritis and the carriers mainly shigellosis, were investigated. The drug was administered at a daily dose of 200 mg twice a day for 3 days to patients with cholera, 7 days to patients with Salmonella enteritis and 5 days to patients with other conditions of infectious enteritis including shigellosis; 1. The efficacy was analyzed in 89 of the 135 patients who received the administration (43 patients with shigellosis, 14 with Salmonella enteritis, 8 with enteropathogenic/ enterotoxigenic Escherichia coli enteritis, 3 with cholera, 7 with enteritis with other pathogenic bacteria, 6 with polymicrobial infectious enteritis and 8 with acute enteritis that was pathogen-negative). 2. In patients bearing symptoms and who thus could be analyzed for drug efficacy, the drug was markedly effective or effective 50/52 (96.2%). 3. Bacteriologically, the drug was effective for Shigella spp. in 41 (100%) of 41, Salmonella spp. in 12 (85.7%) of 14, and enteropathogenic/enterotoxigenic Escherichia coli in 8 of 8 cases. 4. Adverse effects were seen in 5/133 patients (3.8%) receiving the drug, including two cases of skin eruption, one of the numbness of the hands, one of oral aphtha, and one of nausea. In patients for whom laboratory findings were available, 20/115 (17.4%) showed abnormalities, mainly elevations of GOT and/or GPT, but these were slight. 5. In terms of subjective reports of usefulness, 51/82 (62.2%) were markedly satisfied, and 73/82 (89.0%) were either satisfied or markedly satisfied. 6. The influence of administration of BLFX on fecal concentration and intestinal microbial flora was investigated in 2 patients with acute infectious enteritis. Results approximately equivalent to such flora levels in healthy subjects were obtained. These results suggest that BLFX is highly useful for infectious enteritis such as that caused by shigellosis.

The hemolysin produced by group C streptococci (GCH) has an isoelectric point (pI) of 5.6 and a molecular weight of 32,000 and shows hemolytic activity in the absence of 2-mercaptoethanol (2-ME). The hemolytic activity of GCH was compared to that of streptolysin S (SLS). These hemolysins did not differ with respect to the binding and release of hemoglobin (Hb). GCH was bound to phospholipids on the membranes of target erythrocytes, followed by the rapid released of K+ and slow Hb release after a relatively long lag time. GCH showed a lower hemolytic efficiency than SLS, reflecting the fact that these hemolysins destroy erythrocytes by slightly different mechanisms.

イヌ免疫グロブリンA (IgA) の分離精製の材料として胆汁を使用し, DEAE・セルロースを活性化せずバッチ法を用いることにより効率よくIgAが回収できた. これをさらにTEAE・セルロースクロマトグラフィー, セファデックスG-200による濾過によって精製することにより, 高度に精製された免疫学的に単一なイヌIgAが得られた. この精製IgAによって特異抗血清を作成することができた. また, この特異抗血清を用いて免疫電気拡散法によるIgAの定量について検討を行ったところ, 60倍希釈抗血清を使用することにより1.6～13.2mg/dlまで直線性よくIgAの定量が可能であった.

For microbial ecological analysis, 14 strains of Methylobacterium aquaticum isolated from water samples were subjected to clustering analysis on the basis of ribotyping and RAPD-PCR tests. The ribopatterns after digestion with EcoRI obtained from 14 strains of M. aquaticum were used to divide the strains into two groups (Groups I and II) with a similarity of 55%. From the analysis of RAPD patterns using primer 208, the 14 strains were divided into 3 groups (A-C) based on a homology of 45% or greater, and from that using primer 272, there were 4 groups (A-D) based on a homology of 50% or greater. The chlorine resistance (99.9% CT values) of these isolates was also experimentally confirmed, and we attempted to define the connection between chlorine resistance and the geno-cluster. The average CT value of group I was 0.89 mg•min/l and the average of group II was 0.69 mg•min/l. No remarkable differences in the CT values for the groups were found.

A 73-year-old male was admitted to our hospital because of detection of Shigella flexneri 2a from his stool. Antimicrobial treatment with levofloxacin (LVFX) was started, but could not eliminate the organism in the stool. In the examination of drug susceptibility, this strain was highly resistant to all new quinolones. The minimal inhibitory concentration of norfloxacin, ofloxacin and ciprofloxacin to this strain was 12.5 micrograms/ml, 6.25 micrograms/ml and 6.25 micrograms/ml, respectively. The dual mutations were detected in the codon 83 and 87 of the gyrA gene by sequencing the quinolone-resistance determining region (QRDR). There was, however, no significant difference between the intracellular uptake of ciprofloxacin in this strain and in the ciprofloxacin-sensitive strain. The amount of ciprofloxacin in this strain unchanged when carbonyl cyanide m-chlorophenyl hydrazone (CCCP) was added. These results suggest that the advanced resistance in Shigella flexneri against new quinolones could be acquired by only this dual mutations without the change of the active efflux mechanism.

In vitro antibacterial activity of balofloxacin (BLFX), a newly developed fluoroquinoline, was compared with that of norfloxacin (NFLX), ofloxacin (OFLX) and ciplofloxacin (CPFX). Bacterial strains used in this experiment were freshly isolated from patients with infectious enteritis just before BLFX therapy. The isolates were 43 strains of Vibrio cholerae O1, 1 strain of Campylobacter sp., 4 strains of Aeromonas spp., 3 strains of Plesiomonas shigelloides, 1 strain of Vibrio mimicus and 1 strain of Vibrio cholerae non-O1. MIC90 of BLFX against 43 strains of Shigella spp., 13 strains of Salmonella spp. and 9 strains of E. coli were 0.39, 0.39, 0.2 micrograms/ml, respectively. All strains of Aeromonas spp. and P. Shigelloides were inhibited by the concentrations under 0.39 and 0.05 micrograms/ml. MIC90 of BLFX, NFLX, OFLX and CPFX against a total of 79 strains were 0.39, 0.2, 0.2 and 0.05 micrograms/ml, respectively.

Antibacterial activity of fleroxacin (FLRX), a new quinolone antimicrobial, against 36 strains of Shigella app., 14 strains of Salmonella spp., 11 strains of Escherichia coli, 9 strains of Vibrio spp. (including 2 strains of V. cholerae O1), 14 strains of Campylobacter jejuni/coli, 3 strains of Aeromonas spp. and 1 strain of Plesiomonas shigelloides isolated from infectious enteritis patients in this study was determined. Its activity was compared with that of ciprofloxacin (CPFX), norfloxacin (NFLX) and nalidixic acid (NA). The MIC90 values of FLRX were 0.1 microgram/ml against Shigella spp. and E. coli, 0.2 microgram/ml against Salmonella spp. and Vibrio spp., and 12.5 micrograms/ml against C. jejuni/coli MIC90 of FLRX was comparable to that of CPFX and NFLX against Vibrio spp.. Against other species, MIC90 of FLRX were 2- to 4-fold higher than those of CPFX, whereas equal to or 2-fold lower than NFLX. FLRX demonstrated excellent activity against an NA-resistant (MIC: > 100 micrograms/ml) isolate of E. coli, with MIC 0.78 microgram/ml. FLRX showed 8-fold higher activity than NA against other strains. The antibacterial activity of FLRX was compared with that of NA against stocked strains (clinical isolates from August 1989 to February 1991), consisting of 11 strains of Shigella spp., 10 strains of Salmonella spp., 8 strains of E. coli, 10 strains of V. cholerae O1, 10 strains of V. parahaemolyticus and 14 strains of C. jejuni/coli. MICs of FLRX were 0.78 and 12.5-25 micrograms/ml against Shigella spp. and C. jejuni/coli that showed resistance of NA (MIC: > or = 100 micrograms/ml), respectively. Based on the above, although the absolute MICs are low against E. coli and shigella spp., a value of 0.78 micrograms/ml for FLRX suggested that such strains should be considered to be resistant.