Biomedical subjects

S Fukayama

Publications and source records attributed to S Fukayama.

At least 91 records · Page 5Linked to original sources

PubMed1992

[Bacteriological evaluations of combination therapies with minocycline and beta-lactams for methicillin-resistant Staphylococcus aureus. II. cefuzonam plus minocycline].

We performed an in vitro assessment of the antibacterial activity of therapy with cefuzonam (CZON) plus minocycline (MINO) against methicillin-resistant Staphylococcus aures (MRSA) infections. 1. Studies using MINO-susceptible and MINO-resistant MRSA strains suggested that the antibacterial activity of CZON + MINO was dependent on the antibiotic action of MINO, similarly to the case with cefotiam (CTM) + MINO. 2. The antibacterial activity (including the FIC index) of this combination was slightly inferior to that of CTM + MINO. However, the time course of antibacterial efficacy of CZON + MINO in MRSA pretreated with MINO was comparable to that of CTM + MINO. 3. CZON + MINO appeared to be a very useful combination in patients with mixed infections due to MRSA and Gram-negative bacteria.

Ceftizoxime↗

PubMed1992

[Synergistic action of cefodizime and other antimicrobial agents on clinically isolated microorganisms. III. Synergistic action with gentamicin].

An in vitro investigation was done on antimicrobial activities of cefodizime (CDZM) in combination with gentamicin (GM) against clinically isolated Gram-negative rods. The results are summarized as follows. 1. Combined antimicrobial activities were dependent on antimicrobial activities of GM, similar to the CDZM + sisomicin (SISO) combination. The combined activities were concentration dependent, and they were more strongly dependent on GM concentrations than on CDZM concentrations. The obtained results suggested that synergistic or cooperative antimicrobial activities of the combination would be expected when GM concentrations in blood are at or somewhat lower than 1 MIC, and clinical activities would be exerted regardless of the presence of CDZM resistant organisms, similarly to CDZM+SISO combination. 2. It seems possible that, with regard to combinations of beta-lactam antibiotics and aminoglycoside antibiotics, there exist universal rules that combined activities are dependent on activities of aminoglycoside antibiotics, and that stronger concentration dependencies on aminoglycosides would be observed than those on beta-lactams.

Bacteria↗

PubMed1992

[Synergistic action of cefodizime and other antimicrobial agents on clinically isolated microorganisms. IV. Synergistic action with dibekacin].

Antimicrobial activities of cefodizime (CDZM) in combination with dibekacin (DKB) were studied in vitro against clinically isolated Gram-negative rods. The results obtained are summarized as follows. 1. Similarly to combinations of CDZM+sisomicin (SISO) and CDZM+gentamicin (GM), combined activities of CDZM and DKB were dependent on antimicrobial activities of DKB, and the combined activities were more strongly dependent on DKB concentrations than on CDZM concentrations. The obtained results suggested that synergistic or cooperative antimicrobial activities of the combination would be expected when DKB concentrations in blood are at or somewhat lower than 1 MIC, and that clinical activities would be exerted regardless of the presence of CDZM resistant organisms, similarly to CDZM+GM combination. 2. As we have suggested previously, it seems possible that, with regard to combinations of beta-lactam antibiotics and aminoglycoside antibiotics, there exist universal rules that combined activities are dependent on activities of aminoglycoside antibiotics, and that stronger concentration dependencies on aminoglycosides would be observed than those on beta-lactams.

Bacteria↗

PubMed1992

[Antimicrobial activity of cefetamet against fresh clinical isolates of Branhamella catarrhalis].

Against strains of Branhamella catarrhalis which were separated from various RTIs (respiratory tract infections) in 1991 antimicrobial activities (MICs) of cefetamet (CFMT) were determined, and the following conclusions were obtained. 1. The MIC80 of CFMT against B. catarrhalis was 0.39 microgram/ml, which was higher than that of cefixime (CFIX) by one dilution or twofold, but was lower than that of cefpodoxime (CPDX) by two dilutions or fourfold and that of cefotiam (CTM) by three dilutions or eightfold. 2. The fact that all of the 50 strains tested were beta-lactamase producers appeared to indicate that CFMT was stable against BRO-1 and BRO-2 beta-lactamases produced by B. catarrhalis. 3. Blood concentrations of the test drug, CFMT, and control drugs upon normal single doses were calculated using pharmacokinetic parameters. Lengths of time periods during which drug concentrations stayed above their MICs against B. catarrhalis obtained in this study were determined for CFMT, CFIX, CPDX and CTM. They were, respectively, 12 hours, 12 hours, 6 hours, and 2 hours, thus CFMT appeared to remain above MIC for sufficiently long time for the treatment of RTIs which are affected by B. catarrhalis directly or indirectly.

Cefixime↗

PubMed1992

[Antimicrobial activities of ceftriaxone against clinically isolated strains].

Antibiotic activities (MICs) of ceftriaxone (CTRX) against 1,210 strains of bacteria including 28 spp. isolated in 1987 and 1990 were compared with those of other cephems. 1. When compared to data on clinically isolated strains reported in the early 1980s, strains of the following species isolated in 1990 showed extremely elevated MIC90s of CTRX: Staphylococcus spp., Streptococcus pneumoniae, Escherichia coli, Citrobacter spp., Enterobacter spp., Serratia spp., Proteus vulgaris, Morganella morganii and Providencia spp. No changes were observed in MIC90s between the 2 periods for microorganisms such as Streptococcus pyogenes, Haemophilus influenzae, Klebsiella pneumoniae, Proteus mirabilis and Peptostreptococcus spp. 2. The MIC90 of CTRX to S. pneumoniae was high because a large number of benzylpenicillin (PCG)-insensitive S. pneumoniae (PISP) was present among this species. The MIC80 to Bacteroides fragilis group was also high because highly resistant B. fragilis and B. thetaiotaomicron were isolated in large proportions among the bacteria of this group. Other oxime-type cephems also had high MICs against the above mentioned bacteria. Therefore, a further evaluation has to be made with regard to activities of oxime-type cephems such as CTRX against PISP and B. fragilis group. 3. Sample strains included, in high ratios, methicillin-resistant Staphylococcus aureus (MRSA), cephamycin-resistant as well as oxime-type cephem-resistant intestinal bacteria, Gram-negative bacteria, and new-quinolone-resistant bacteria. Some of there resistant bacteria are also CTRX-resistant, and CTRX had insufficient activities against them. 4. With regard to the assessment of changes of frequencies of specific drug-resistant bacteria, including those with CTRX-resistance from year to year, the authors would like to point out the following comment of theirs made in 1989 and 1991, which appears to be increasing its significance, "Subjects of future studies should include dose on the mechanisms for the acquisition of bacterial resistance to entire beta-lactam antibiotics and the social circumstances in which resistant bacteria appear". 5. It appears that those strains resistant to cephems including CTRX are increasingly found among clinically isolated strains in recent years. CTRX, however, was found still effective against most clinical pathogens. Furthermore, considering that CTRX is one of the few drugs which sustain high blood concentrations of active forms we concluded that CTRX is a useful cephem-group antibiotic.

Bacteria↗

PubMed1991

Protein kinase A-dependent inhibition of alkaline phosphatase release by SaOS-2 human osteoblastic cells: studies in new mutant cell lines that express a cyclic AMP-resistant phenotype.

We have established mutant SaOS-2 cell lines that express a cyclic AMP (cAMP)-resistant phenotype to investigate the regulation and functional importance of orthophosphoric-monoester phosphohydrolase alkaline optimum (ALPase) in the action of parathyroid hormone (PTH). Cells were stably transfected with a plasmid that directs the synthesis of a mutant form of the type I regulatory subunit of protein kinase A (PKA) under the control of the metallothionein promotor. There was no significant difference between parental SaOS-2 cells and the mutant lines in the affinity or number of receptors for 125I-Nle8,18Tyr34bPTH1-34NH2, either in the absence or presence of Zn2+. When cAMP-dependent gene transcription was examined using transient transfection with a somatostatin promoter-chloramphenicol acetyl transferase (CAT) reporter plasmid, CAT activity stimulated by human PTH and dibutyryl cAMP (DBcAMP) was inhibited by greater than 90% in the presence of Zn2+ in the mutant cell lines. In contrast, activation by a phorbol ester of a pentameric collagenase promoter/CAT construct containing five tandem copies of the AP-1 response element (5x-TRE-CAT) was unaffected in Zn(2+)-treated mutant cells. The inhibitory actions of PTH and DBcAMP on ALPase release were blunted by up to 80-90% in the mutant cell lines in the presence of Zn2+; there were no significant differences in the magnitude of inhibitory effects between these agonists. We conclude that the inhibitory action of PTH on ALPase release in SaOS-2 cells is mediated via activation of PKA. These cAMP-resistant cell lines will be especially useful in elucidating signal transduction mechanism(s) for PTH in human osteoblastic cells.

Alkaline Phosphatase↗

PubMed1991

[Biological types and drug-sensitivities of multiple strains of freshly isolated methicillin-resistant Staphylococcus aureus].

Biological studies were done on numbers of methicillin-resistant strains of Staphylococcus aureus (MRSA) either clinically isolated at medical institutes nationwide and sent to us or isolated and identified by us from samples obtained in the year 1990 from patients with various infections. The results of the studies are summarized as follows. 1. The origins of the 1,047 strains used in our studies included arterial and venous blood samples (6.9%), samples from the respiratory tract (43.3%), surgical and dermatological samples (30.2%), otorhinolaryngological and ophthalmological samples (3.8%), urological samples (7.2%), fecal samples (5.1%) and others (3.6%), thus samples from the respiratory tract were the most frequent. 2. The strains were classified according to coagulase types into type II (76.4%), type III (2.1%), type IV (15.4%), type VII (5.3%) and other types (0.8%), thus type II strains were the most numerous. When classified according to their origins, type II strains were found in a significantly high frequency in respiratory tract samples, and type IV strains appeared to be present at relatively high frequencies in the surgical, dermatological, otorhinolaryngological and ophthalmological samples. Some coagulase types were found more frequently in samples from some institutes than in others, but coagulase type distributions were similar in different localities. 3. The strains were classified according to their enterotoxin types into type A (22.8%), type B (10.5%), type C (54.9%) and other types (11.7%), thus type C strains were the most frequent. Significant correlations were observed between enterotoxin type C and coagulase type II, and type A and type IV. 4. Defining strains with minimum inhibitory concentrations (MICs) of greater than or equal to 100 micrograms/ml as high MRSA and less than or equal to 50 micrograms/ml as moderate MRSA, 94.8% of coagulase type II strains were high MRSA and 78.9% of coagulase type IV strains were moderate MRSA, thus coagulase type II strains tended to be high in methicillin resistance. 5. MIC50 and MIC90 of vancomycin (VCM) against many of these strains of MRSA were 0.78 and 1.56 micrograms/ml, respectively, suggesting that VCM has also a potent antibacterial activity against recent isolates of MRSA in Japan.

Cefamandole↗

PubMed1991

[Synergistic action of cefodizime and other antimicrobial agents on clinically isolated microorganisms. I. Synergistic action with minocycline].

Since cefodizime (CDZM) shows a broad antimicrobial spectrum and relatively long half life in blood, we examined its synergistic action with minocycline (MINO) in vitro against Staphylococcus aureus. 1. CDZM in the presence of MINO, most of cases 1 MIC showed FIC index greater than 0.5-less than or equal to 2 against methicillin-susceptible S. aureus (MSSA), thus the results suggested a synergistic action against S. aureus. 2. CDZM in combination with MINO at 1 MIC or sub MIC where therapeutically a favorable efficacy is expected on MINO-susceptible strains exhibited FIC index less than or equal to 0.5-less than or equal to 1, Methicillin-resistant S. aureus (MRSA), thus suggesting a synergistic action against MINO-susceptible MRSA strains. Synergism was hardly recognized against MINO-resistant MRSA strains, however. 3. Synergism by both drugs was produced in MINO-susceptible strains of S. aureus including MRSA where MIC by CDZM was high or moderate, but no synergism was demonstrated against MINO-resistant strains. That is, synergistic action by both drugs was thought to depend on antimicrobial activity of MINO.

Cefotaxime↗

PubMed1991

[Combined antibacterial activity of aztreonam and clindamycin against clinically isolated strains].

It has been reported in some studies that the combination of aztreonam (AZT) and clindamycin (CLDM) have high clinical effectiveness in the treatment of intractable infections. We, therefore, studied combined in vitro antibacterial activity of these 2 compounds using many freshly isolated strains. 1. AZT and CLDM in combination had synergistic effects on Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, and Haemophilus influenzae, which are sensitive or quasi-sensitive to CLDM, in the presence of CLDM at MIC or sub-MIC. 2. For Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii, Enterobacter cloacae, Serratia marcescens, and Pseudomonas aeruginosa, which are not sensitive to CLDM, the 2 drugs in combination showed synergistic effects on some species and additive or slightly additive effects on most species in the presence of CLDM at those concentrations which are usually maintained in blood. 3. The 2 drugs showed no antagonism.

Aztreonam↗

PubMed1991

[Bacteriological study on fosfomycin against organisms clinically isolated from paranasal sinusitis].

Multi-center bacteriological and clinical studies on fosfomycin (FOM) nasal solution were performed in subjects with paranasal sinusitis from January, 1988 to May, 1990. In these studies, we were exclusively responsible for bacterial isolation from clinical sources, bacterial identification and the determination of drug susceptibility. Before local administration of FOM nasal solution, many strains of various bacterial species were isolated from sources totalling 396 cases involved in phase II clinical studies, dose-finding and open clinical studies. From antibacterial activities of FOM against those isolates, we obtained the following conclusions. 1. Among the 447 isolates, Streptococcus spp. occupied 25.7%, Staphylococcus spp. 21.7% and anaerobic Gram-positive cocci (GPC) 13.6%, showing high detection frequency of aerobic and anaerobic GPC. Next to these, Haemophilus influenzae, Pseudomonas aeruginosa, Klebsiella spp. and Branhamella catarrhalis also were often obtained. 2. After exclusion of possibly contaminating strains which might have entered into cultures at samplings or transfers, the MIC50 and the MIC80 of FOM against the remaining 354 isolates were determined to be 12.5 and 25 micrograms/ml, respectively, indicating that local use of FOM would be fully effective to eradicate most of the bacteria. 3. FOM nasal solution showed sufficient eradication efficacy against most clinical isolates of possible causative organisms of paranasal sinusitis, and appeared to be useful as a topical preparation for the treatment of this disease.

Administration, Intranasal↗

PubMed1991

[Antimicrobial activity of cefpiramide to fresh clinical isolates].

In the subjects of 835 strains of 37 clinically isolated microbial strains, which were separated and identified among materials collected from patients with various infections and which were sent from medical therapeutic institutions throughout Japan in 1990, for the purpose of examining the antimicrobial activity of cefpiramide (CPM), its minimum inhibitory concentration (MIC), together with those of other cephem antibiotics, was determined, and the following conclusions were obtained. 1. Microbial strains in which no CPM-resistant strains emerged were Streptococcus pyogenes, Streptococcus pneumoniae and Anaerobic Gram-positive cocci. 2. In comparison with reports by many researchers at the former half of the 1980s, microbial stains suggesting an increase in resistance to CPM were Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas cepacia, Pseudomonas putida, Acinetobacter calcoaceticus, and Haemophilus influenzae, but also in other microbial strains the resistance to CPM was observed in high ratios. 3. Among strains used in the test, methicillin-resistant S. aureus, cephamycin and oxime type cephalosporin-resistant Gram-negative bacilli of Enterobacteriaceae, and new quinolone-resistant microbes were observed in high ratios; therefore, it was considered that CPM could not exert sufficient antimicrobial activities to these strains because of many resistant strains being complicated among these "CPM-resistant strains". 4. It was discussed that "the resistance mechanism observed throughout beta-lactam drugs as a while and the study themes in the dimension including social circumstances where resistant strains emerged", as pointed out by the authors in 1989, increased the significance of these days in the evaluation of timecourse changes in microbes resistant to specific drugs including CPM. 5. There are many unfavorable conditions in the antimicrobial activities of CPM to clinically isolated strains in recent years. However, it was jointly confirmed that CPM maintained effective antimicrobial activities to the majority of clinically isolated strains. Furthermore, when it was additionally considered that CPM was one of not many cephem drugs having persistent blood levels, a conclusion was drawn that CPM was one of clincally useful cephem drugs even at present.

Anti-Bacterial Agents↗

PubMed1991

[Antibacterial activities of ofloxacin against recent isolates from patients with community-acquired infections].

In order to survey antibacterial activities of ofloxacin (OFLX) against 1,440 bacterial strains isolated from patients with community-acquired infections in 1987 and 1990, minimum inhibitory concentrations (MICs) of the drug as well as those of other new quinolones and oral cephems were determined. The following conclusions were reached. 1. Comparison of the MIC distribution for strains isolated in 1987 with those in 1990 suggested a tendency toward an increase in the frequency of OFLX-resistant isolates with the passage of time of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Citrobacter spp., Klebsiella ssp., Enterobacter spp., Proteus vulgaris, Morganella morganii, Providencia spp., and Acinetobacter calcoaceticus. Most common elevations of MIC values against these bacteria were observed in MIC80 and MIC90 values, while no significant alteration was observed in MIC50 values. However, MIC50's of OFLX against Serratia marcescens and Pseudomonas aeruginosa were relatively high for strains isolated in both 1987 and 1990. Most of the OFLX-resistant strains of S. aureus seemed to be methicillin-resistant (MRSA). Furthermore, MIC80 of OFLX against coagulase-negative staphylococci was high in strains isolated in both 1987 and 1990. 2. Susceptibility of Streptococcus spp. was evaluated only in strains isolated in 1990. The results were comparable to those reported by others in the early 1980s. 3. Bacteria which showed no or infrequent emergence of OFLX-resistant strains even in 1990 were Proteus mirabilis, Haemophilus influenzae, Neisseria gonorrhoeae, Campylobacter spp. and Peptostreptococcus spp. 4. Recently isolated strains from patients with community-acquired infections showed a tendency toward an increase of the frequency of OFLX-resistant strains among many bacteria. However, the bacteria which contained high percentages of OFLX-resistant strains except for MRSA were so-called less-virulent bacteria, and in the other bacteria elevations of MIC values were only observed in MIC80 and MIC90. These results suggested that OFLX preserved a potent antibacterial activity against bacteria which were major causative pathogens in community-acquired infections.

Bacteria↗

PubMed1991

[Antibacterial activity of ciprofloxacin against fresh clinical isolates from superficial suppurative foci].

The minimum inhibitory concentrations (MICs) of 5 drugs (ciprofloxacin (CPFX), and 4 drugs used as standard) were determined to investigate antibacterial potencies of CPFX against bacterial strains isolated in 1989 from superficial suppurative foci. The clinical isolates tested included 375 strains from 11 aerobic bacterial species, and 50 strains from 2 anerobic bacterial genera (group) for a total of 425 isolates. Interpreting MIC level distributions of these drugs as the expression of antibacterial potencies, the results are as follows. 1. When activities of new-quinolone antibiotics were tested, we found that, CPFX expressed far superior antibacterial potency to ofloxacin (OFLX) and norfloxacin (NFLX) against coagulase-negative staphylococci, Enterococcus faecalis, Enterococcus faecium, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Proteus mirabilis, Proteus vulgaris, Morganella morganii, Pseudomonas aeruginosa and Peptostreptococcus spp., although the activity of CPFX against Bacteroides fragilis group was weaker than that of OFLX, and CPFX had similar activity against Staphylococcus aureus to OFLX. 2. In comparison to beta-lactam antibiotics, CPFX was inferior to amoxicillin (AMPC) against E. faecalis and inferior to AMPC and cefaclor (CCL) against Peptostreptococcus spp. Against all other bacterial species, however, CPFX expressed superior antibacterial potency to AMPC and CCL. 3. Scattered findings of low sensitivity or resistance to CPFX were observed among the S. aureus, E. faecalis, E. faecium, P. vulgaris, M. morganii, P. aeruginosa and B. fragilis (group) species, but with an exception of E. faecium, the incidence of resistance strains was low.

Amoxicillin↗

PubMed1990

Stimulation by parathyroid hormone of 45Ca2+ uptake in osteoblast-like cells: possible involvement of alkaline phosphatase.

We have investigated the actions of human PTH [hPTH-(1-34)] on the association of 45Ca2+ with two human (SaOS-2 and MG-63) and two rat (ROS 17/2.8 and UMR-106) osteoblast-like cell types. In SaOS-2 cells, hPTH-(1-34) binds to specific membrane receptors to activate adenylate cyclase. Treatment of SaOS-2 cells with hPTH-(1-34) resulted in an increase in 45Ca2+ uptake, in a dose-dependent fashion, up to 2- to 4-fold above control values. The increase was first evident at 10 min and persisted for at least 30 min. Treatment with nimodipine, a calcium channel antagonist, was without effect on the stimulatory action of PTH. A similar enhancement of cell-associated 45Ca2+ was observed when the cells were incubated with vasoactive intestinal peptide, which acts via different receptors to activate adenylate cyclase in SaOS-2 cells. Treatment with (Bu)2cAMP also induced an increase in cell-associated 45Ca2+. Pretreatment of SaOS-2 cells with hPTH-(1-34) for 4 h, which induced homologous desensitization to a second challenge with the same peptide for stimulation of cAMP production, did not attenuate the further enhancement of cell-associated 45Ca2+ by a second treatment with hPTH-(1-34). We then examined a possible relationship between alkaline phosphatase (ALPase) and 45Ca2+ uptake. SaOS-2 cells contained high levels of alkaline phosphatase activity and continuously released the enzyme into the medium. Release was enhanced by treatment with hPTH-(1-34) for 10 min. Incubation of cells with levamisole (an inhibitor of the liver/bone/kidney type of ALPase) resulted in a rapid decrease in basal and PTH-stimulated 45Ca2+ uptake, while treatment with L-Phe-Gly-Gly (an inhibitor of human placental ALPase) was without effect. Treatment of the cells with ALPase (bovine kidney) enhanced 45Ca2+ uptake. In MG-63 cells, a stimulatory effect of hPTH-(1-34) on cell-associated 45Ca2+ was also observed; however, hPTH-(1-34) did not stimulate cAMP production in MG-63 cells. In ROS 17/2.8 cells, neither hPTH-(1-34) nor rat PTH-(1-34) stimulated an increase in cell-associated 45Ca2+, while in UMR-106 cells, rat PTH-(1-34) and (Bu)2cAMP did enhance 45Ca2+ uptake, although hPTH-(1-34) was without effect. We conclude that PTH can stimulate an increase in cell-associated 45Ca2+ in several osteoblast-like cell lines, possibly by modulating local ALPase activity; however, this action of PTH does not appear to be obligatorily dependent on the adenylate cyclase-stimulating action of PTH.

Alkaline Phosphatase↗

PubMed1990

[Study on susceptibilities of freshly isolated strains to macrolide antibiotics].

Macrolide (ML) susceptibilities of clinically isolated bacteria obtained freshly during 1989 were determined and year to year differences in ML-resistances of the clinical isolates in our laboratory were examined with epidemiological consideration in mind. 1. The distribution of minimum inhibitory concentrations (MICs) of MLs against isolates of Staphylococcus aureus showed 2 peaks, one peak representing S. aureus isolates susceptible to MLs and the other peak representing those resistant to MLs. Proportions of resistant isolates to various MLs were 36% to erythromycin, 24% each to kitasamycin, josamycin, midecamycin and midecamycin acetate. MICs of rokitamycin (RKM), however, distributed themselves into 3 peaks of less than or equal to 0.39 micrograms/ml (76%), 1.56-3.13 micrograms/ml (12%) and greater than or equal to 100 micrograms/ml (12%). Staphylococcus spp. including Staphylococcus epidermidis showed different resistance characteristics to 14-membered ring MLs and to 16-membered ring MLs. Further, the proportion of resistant organisms to RKM was the smallest among proportions of resistant organisms to various 16-membered ring MLs tested. These differences in proportions of resistant organisms to different MLs may have resulted from differences in resistance induction activities of different MLs. The above described ratios of resistant organisms to MLs among S. aureus did not vary since 1975 among clinical isolates tested in our laboratory. 2. Four per cent (4%) of Streptococcus pyogenes isolates were MLs resistant, and 18% of Streptococcus pneumoniae isolates were resistant to MLs. Among the isolates tested in our laboratory since 1985, resistant isolates of S. pyogenes are clearly decreasing and those of S. pneumoniae seem to be increasing.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗

PubMed1990

[Antimicrobial activities of gentamicin against fresh clinical isolates].

Antimicrobial activities of gentamicin (GM), compared with activities of other aminoglycosides (AGs) and beta-lactam antibiotics, were studied against clinical isolates obtained during a period of July-December 1989. 1. GM-resistant strains were noted in 24% of Staphylococcus aureus, 12% of Enterobacter spp., 24% of Serratia marcescens, 7% of Morganella morganii and 26% of Pseudomonas aeruginosa, but no GM-resistant strains were observed among isolates of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Proteus vulgaris. 2. A majority of GM-resistant strains of S. aureus were methicillin-resistant S. aureus (MRSA) and a large number of GM-resistant strains of Enterobacter spp. was also resistant to new quinolones. GM showed, however, strong antimicrobial activities against new quinolones-resistant strains of S. marcescens, M. morganii and P. aeruginosa. 3. Among all the isolates tested of S. marcescens, 24% were GM-resistant, 72% were tobramycin (TOB)-resistant, 86% were dibekacin (DKB)-resistant and 64% were amikacin (AMK)-resistant, hence the incidence of GM-resistant strains was the lowest. This tendency was also observed with P. vulgaris. However, among P. aeruginosa, 26% were GM-resistant, 14% TOB-resistant, 18% DKB-resistant and 22% AMK-resistant, thus the incidence rate for GM-resistance was somewhat higher. These results suggest that different AGs-modification enzymes were produced by various clinical isolates under the present condition. 4. Comparing the ratio of GM-resistant strains in the present study with those in 1980 and 1983, the ratio increased among S. aureus, while decreases were observed among Enterobacter spp., S. marcescens, P. vulgaris and P. aeruginosa, indicating that a unilateral tendency of increases in GM-resistant strains did not exist among clinical isolates over the years.

Anti-Bacterial Agents↗

PubMed1990

[Synergy between sulbactam and ampicillin or cefoperazone in antimicrobial activity against beta-lactamase producing microorganisms. Results with the use of microdilution broth method].

Antimicrobial activities of sulbactam (SBT) with ampicillin (ABPC) or with cefoperazone (CPZ), in other words, the effects of SBT, an beta-lactamase inhibitor, against beta-lactamase producing strains of clinical isolates, were studied using microdilution broth method. 1. beta-Lactamase producing strains such as Staphylococcus aureus, Branhamella catarrhalis, Haemophilus influenzae, Escherichia coli and Klebsiella pneumoniae decompose benzylpenicillin (PCG) which is one of substrates of the acid-metry disc method and show a strong reaction, while they do not decompose cefazolin (CEZ), another substrate, showing no or weak reaction. Thus, it is suspected that beta-lactamases produced by these organisms are mainly penicillinase (PCase). MIC-distributions of ABPC and CPZ against these clinical isolates which seemed to produce PCase shifted to lower MIC ranges with MIC's reduced to 1/4 or below when 0.025 to 0.39 microgram/ml of SBT was added. 2. It appears that beta-lactamase produced by Proteus vulgaris may be oxyiminocephalosporinase (CXase), because P. vulgaris showed strong reaction on CEZ, but moderate reaction on PCG in the acid-metry disc method. MIC-distribution of ABPC and CPZ against P. vulgaris shifted to a lower range with MIC's of 1/4 or below when 0.20 to 0.39 microgram/ml of SBT was added. 3. All the test strains of Pseudomonas aeruginosa showed strong reaction on CEZ but only 56% of the test strains showed reaction on PCG. It appears that the beta-lactamases which showed strong reaction on CEZ is cephalosporinase and is encoded in chromosome, while those beta-lactamase that showed strong reaction on PCG is encoded in a plasmid which was acquired secondarily by P. aeruginosa. MIC-distribution of CPZ against P. aeruginosa shifted to a lower range with MIC values of 1/2 or below with the addition of SBT at 1.56 micrograms/ml. 4. It appears that the synergy of SBT with ABPC or with CPZ against the PCase or CXase producing strains may occur in the presence of SBT at a concentration far less than that reported previously.

Ampicillin↗

PubMed1990

[Annual changes in susceptibility of clinical isolates to midecamycin acetate].

To investigate annual changes in the susceptibility of clinical isolates to midecamycin acetate (MDM-AC), minimum inhibitory concentrations (MICs) of MDM-AC were determined for clinical isolates obtained from outpatients since 1985. MDM-AC-resistant strains of Staphylococcus spp. and Streptococcus spp. have shown similar degrees of resistance to midecamycin and josamycin. Regarding this as macrolide resistance, proportions of macrolide-resistant strains tended to increase for Staphylococcus aureus and Streptococcus pneumoniae but to decrease for Streptococcus pyogenes. 1. For S. aureus, 8% of the strains isolated in 1985, 20% in 1987 and 20% in 1989 were macrolide-resistant. Of these macrolide-resistant strains, 70% or more in 1987 and 80% or more in 1989 were methicillin-resistant S. aureus (MRSA). 2. For S. pneumoniae, 8% of the strains isolated in 1985, 12% in 1987 and 12% in 1989 were macrolide-resistant, indicating a tendency for resistant strains to increase annually. 3. For S. pyogenes, 8% of the strains isolated in 1985, 4% in 1987 and 0% in 1989 were macrolide-resistant, showing a decreasing tendency. 4. MDM-AC is still thought to be a clinically useful antibacterial agent because it still shows antibacterial activity against 80% or more of Gram-positive cocci clinically isolated in recent years and a low degree of induction of macrolide resistance in Staphylococcus spp.

Bacterial Infections↗