Search PubMed⌕ Search

Biomedical subjects

Keizo Yamaguchi

Publications and source records attributed to Keizo Yamaguchi.

At least 91 records · Page 5Linked to original sources
PubMed2003

[Analysis of period of positive urinary antigen detection kit for Streptococcus pneumoniae in patients with pneumococcal pneumonia].

The objectives of this study were to investigate the usefulness of the urinary antigen detection kit for Streptococcus pneumoniae and to analyze the duration of urinary antigen presence in pneumococcal pneumonia. We evaluated this kit in 51 patients whose symptoms and laboratory data suggested pneumococcal pneumonia and who were admitted to Toho University Hospital (Tokyo, Japan) between July 2000 and June 2001. S. pneumoniae urinary antigen was detected in 21 of 51 patients. These 21 patients were further investigated with their clinical characteristics and the duration of a positive urinary antigen reaction. S. pneumoniae was isolated by sputum or blood culture in 10 cases (47.6%), whereas 11 cases (52.4%) showed positive results only with urinary antigen but not in cultures. When the urinary antigen kits were tested, 19 cases (90.5%) were treated with antibiotics. Eleven of the 21 patients were continuously tested with this kit. The mean duration for which these patients were urinary antigen-positive was 7.3 weeks. Patients whose pneumonia was severe or who had positive culture results tended to be positive for urinary antigen for a prolonged period. This kit has high sensitivity and specificity, is suitable for rapid diagnosis and is effective after antibiotic therapy. However, because the positive test kit results are prolonged after recovery from pneumonia in some cases, this kit is not suitable for the evaluation of therapeutic effect.

Adult↗
PubMed2003

[Activities of antimicrobial agents against 8,474 clinical isolates obtained from 37 medical institutions during 2000 in Japan].

A survey was conducted to determine the antimicrobial activity of fluoroquinolones and other antimicrobial agents against 8,474 clinical isolates obtained from 37 Japanese medical institutions in 2000. A total of 25 antimicrobial agents were used, comprising 4 fluoroquinolones, 13 beta-lactams, minocycline, chloramphenicol, clarithromycin, azithromycin, gentamicin, amikacin, sulfamethoxazole-trimethoprim, and vancomycin. A high resistance rate of over 85% against fluoroquinolones was exhibited by methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecium. Isolates showing resistance to fluoroquinolones among methicillin-resistant coagulase-negative Staphylococci, Enterococcus faecalis, and Pseudomonas aeruginosa from UTI accounted for 30-60%. However, many of the common pathogens were still susceptible to fluoroquinolones, such as Streptococcus pneumoniae (including penicillin-resistant isolates), Streptococcus pyogenes, methicillin-susceptible S. aureus (MSSA), methicillin-susceptible coagulase-negative Staphylococci, Moraxella catarrhalis, the Enterobacteriaceae family, and Haemophilus influenzae (including ampicillin-resistant isolates). About 85% of P. aeruginosa isolated from RTI were susceptible to fluoroquinolones. In conclusion, this survey of sensitivity to antimicrobial agents clearly indicated trend for increasing resistance to fluoroquinolones among MRSA, Enterococci, and P. aeruginosa isolated from UTI, although fluoroquinolones are still effective against other organisms and P. aeruginosa from RTI as has been demonstrated in previous studies.

Anti-Bacterial Agents↗
PubMed2003

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2001). I. Susceptibility distribution].

The bacterial strains isolated from patients diagnosed as having urinary tract infections (UTIs) in 10 institutions in Japan were supplied between the period of September and December 2001. Then, the susceptibilities of them to a variety of antimicrobial agents were investigated. The number of them were 496 strains. The breakdown of these strains was Gram-positive bacteria as 29.6% and Gram-negative bacteria as 70.4%. Susceptibilities of these bacteria to antimicrobial agents were as follows; against Staphylococcus aureus, vancomycin (VCM) showed a strong activity, and this drug also had a strong activity against MRSA in preventing growth of all strains at 1 microgram/mL. In addition, arbekacin (ABK) showed strong activity with the MIC90 of 2 micrograms/mL against MRSA and prevented growth of all strains at 4 micrograms/mL. ABK also showed a strong activity against Staphylococcus epidermidis in preventing growth of all strains at 0.5 microgram/mL. Ampicillin (ABPC) and cefozopran (CZOP) showed a relatively strong activity against S. epidermidis (MIC90: 8 micrograms/mL). ABPC, imipenem (IPM), and VCM showed strong activities against Enterococcus faecalis. No increase of low-susceptible strains in E. faecalis was observed against these antimicrobial agents. Against Escherichia coli, carbapenems showed the highest activities: meropenem (MEPM) prevented growth of all strains at 0.25 microgram/mL; IPM prevented growth of all strains at 0.5 microgram/mL. CZOP and cefotiam (CTM) also showed strong activities against E. coli: MIC90 of CZOP was within 0.125 microgram/mL; MIC90 of CTM was within 0.5 microgram/mL. Quinolone-resistant E. coli was detected at frequency of 9.3%, which was lower than that in the last year, and was higher level than those in up to 1999. MEPM showed the strongest activity against Citrobacter freundii in preventing growth of all strains at 0.125 microgram/mL. Almost all drugs showed strong activities against Klebsiella pneumoniae and Proteus mirabilis, and MEPM prevented growth of all strains within 0.125 microgram/mL. Against Serratia marcescens, the MIC90 of gentamicin (GM) was the lowest value being 2 micrograms/mL, and those of IPM and carumonam were 8 and 16 micrograms/mL, respectively. Against Pseudomonas aeruginosa, almost all drugs were not so active. The MIC90 of GM was 8 micrograms/mL, those of IPM and amikacin were 16 micrograms/mL, and those of all other drugs were over than 32 micrograms/mL.

Anti-Bacterial Agents↗
PubMed2003

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2001). II. Background of patients].

Five-hundred thirty one bacterial strains isolated from 412 patients diagnosed as having urinary tract infections (UTIs) in 10 institutions in Japan were supplied between September and December 2001. Then, the clinical background of patients were investigated such as sex, age, and type of infections, infections and kind of bacteria, frequency of bacteria isolation by age and infections, bacteria and infections by timing of antibiotics administration, and bacteria and infections by surgical procedures. With regard to the relationship between age and sex of patients and type of infections, the number of cases aged lower than 50 years was few and complicated UTIs without indwelling catheter was the most frequent in male patients. In females, the number of patients aged lower than 20 years was few. Most of female patients aged lower than 80 years had uncomplicated UTIs. As for the relationship between type of infections and kind of bacteria, Escherichia coli decreased as the infections were more complicated, and Pseudomonas aeruginosa and Enterococcus faecalis increased as the infections were more complicated. In relation of these results to age of patients, isolation frequency of E. coli gradually decreased with aging in patients aged 20 years and older with uncomplicated UTIs. The isolation frequencies of E. faecalis decreased with aging in the patients with complicated UTIs without indwelling catheter while P. aeruginosa decreased with aging in the patients with complicated UTIs with indwelling catheter. E. coli was isolated a few after administration of antibiotics, and P. aeruginosa and E. faecalis were frequently isolated after administration in the patients with all types of infections. As for type of causative organisms in UTIs and with or without surgical operation, E. coli was frequently isolated in the patients without surgery in the patients with uncomplicated UTIs and complicated UTIs without indwelling catheter, while P. aeruginosa was frequently isolated in the patients who underwent surgery in the patients with uncomplicated UTIs and complicated UTIs with indwelling catheter. In uncomplicated UTIs, isolation frequencies of Klebsiella spp., P. aeruginosa, and E. faecalis were significant in the patients with surgery. In complicated UTIs without indwelling catheter, Klebsiella spp. was frequently isolated in the patients with surgery. In complicated UTIs with indwelling catheter, S. aureus and Staphylococcus spp. were frequently isolated in the patients without surgery.

Adolescent↗
PubMed2003

[Nationwide sensitivity surveillance of ciprofloxacin and various parenteral antibiotics against bacteria isolated from patients with severe infections--the first Ciproxan IV special investigation in 2001].

The parenteral injection of ciprofloxacin (CPFX), a fluoroquinolone antimicrobial drug, was approved in September 2000 and a re-examination period of 6 years was set at that time. As a special investigation to apply for re-examination of this drug, it has been planned to conduct 3 nationwide surveillances during the re-examination period by collecting clinically isolated bacteria from patients with severe infections, to whom the drug was mainly indicated, and examining drug susceptibilities of the bacteria to various parenteral antimicrobial drugs including CPFX. This time, we determined the minimum inhibitory concentrations (MICs) of various parenteral antimicrobial drugs including CPFX against 1,220 strains isolated from patients with severe infections by the micro-liquid dilution method and compared susceptibilities of various clinically isolated bacteria to CPFX with those to other antimicrobial drugs. Gram-positive bacteria were less susceptible to CPFX than to carbapenems except 2 bacterial species, Enterococcus faecium and Enterococcus avium but susceptibilities of methicillin-susceptible Staphylococcus aureus (MSSA), Staphylococcus epidermidis and Enterococcus faecalis to CPFX were comparable to those to cefozopran. Susceptibility of Streptococcus pneumoniae to CPFX did not differ among ampicillin (ABPC)-susceptible Streptococcus pneumoniae (MIC of ABPC: < 0.25 microgram/ml), ABPC-intermediate S. pneumoniae (MIC of ABPC: 0.25-2 micrograms/ml) and ABPC-resistant S. pneumoniae (MIC of ABPC: > or = 4 micrograms/ml) MIC90 of CPFX: 1 microgram/ml) and a decrease in the antimicrobial activity seen among cephem and carbapenem antimicrobial drugs against penicillin-intermediate strains was not noted with CPFX. Gram-negative bacteria were susceptible to CPFX similarly to carbapenems and the MIC90 values of CPFX were in the range from < or = 0.063 to 2 micrograms/ml against strains except Stenotrophomonas maltophilia and Burkholderia cepacia. Pseudomonas aeruginosa was most susceptible to CPFX among the antibacterial drugs examined and the MIC90 was 2 micrograms/ml. CPFX also showed the lowest MIC90 value (0.5 microgram/ml) against beta-lactam-resistant P. aeruginosa among the drugs examined. When extended-spectrum beta-lactamase (ESBL) production and class B beta-lactamase production were examined in 439 strains of Enterobacteriaceae and 168 strains of glucose non-fermentative bacteria out of the Gram-negative bacteria collected this time, 3 strains (0.49%) producing ESBL and 7 strains (1.15%) producing class B beta-lactamase were found. The MIC range of CPFX to these 10 strains was between < or = 0.063 to 8 micrograms/ml and 5 strains among those showed susceptibilities (MIC of CPFX: 1 microgram/ml) based on the NCCLS breakpoint. CPFX also showed a satisfactory result concerning susceptibilities of major causal bacteria based on the report of the committee of Japan Society of Chemotherapy on the standard method for determination of susceptibility to antimicrobial agents, the breakpoint of pneumonia. Furthermore, susceptibilities of various bacteria isolated clinically from patients with severe infections this time did not differ much from the result of the nationwide surveillance which we conducted in 1997. Thus, it was concluded that the antimicrobial activity of CPFX was maintained in the post-marketing surveillance for its parenteral preparation.

Adolescent↗
PubMed2003

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2001). III. Secular changes in susceptibility].

The bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa) isolated from patients diagnosed as urinary tract infections (UTIs) in 10 institutions in Japan were supplied between September and December, 2001. Then, the susceptibilities of these bacteria to various antimicrobial agents were examined, and the results were compared with those obtained between 1992 and 2000. Comparison was made by classifying strains isolated from patients into those in uncomplicated UTIs and those in complicated UTIs (including with or without indwelling catheter). The drug sensitivity of S. aureus in this year was comparable to those in up to the previous year, and S. aureus showed the best susceptibility to vancomycin (VCM). E. faecalis showed good susceptibility to ampicillin and imipenem, and the MIC90s were 2 micrograms/mL. The susceptibility of E. faecalis to VCM was also good. E. coli showed good susceptibility to the drugs except penicillins. Among cephems, the susceptibility to cefozopran (CZOP) was better (MIC90: < or = 0.125 microgram/mL). Just as the last report, the decreases in susceptibility of E. coli to quinolones were also observed in the patients with complicated UTIs. The susceptibility of Klebsiella spp. to all the test drugs did not significantly change in 2001 and was generally good but not to penicillins. Among cephems, Klebsiella spp. showed good susceptibility to flomoxef, cefpirome, cefixime, and CZOP with < or = 0.125 microgram/mL of MIC90s either in uncomplicated or complicated UTIs. Although the drug sensitivity of P. aeruginosa was generally low, the detection of the strains that showed good susceptibility to quinolones and carbapenems (MIC: < or = 0.125-2 micrograms/mL) were relatively frequent.

Anti-Bacterial Agents↗
PubMed2002

Cefcapene inactivates chromosome-encoded class C beta-lactamases.

The stability of cefcapene and cefpodoxime, oral antibacterial cephalosporins, toward different classes of beta-lactamases was evaluated. For the class A beta-lactamases, TEM-1, SHV-1, and NMC-A, only the steady-state kinetic parameter ( k(cat)/ Km) values were calculated (3100 - 1.1 x 10(7) M(-1) x s(-1)), because these enzymes have very high Km values for cefpodoxime and cefotaxime. As for class B beta-lactamases L1, IMP-1, and CcrA, in general, similar k(cat)/ Km values were obtained. However, regarding class C beta-lactamases from Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, and Citrobacter freundii, we found major differences in stability between the two compounds. Cefpodoxime acted as a good substrate for the class C beta-lactamases, except for the enzyme from E. cloacae; its k(cat) and Km values were successfully calculated ( k(cat)/ Km, 1.8 x 10(5) - 1.2 x 10(7) M(-1) x s(-1)). On the other hand, cefcapene acted as a poor substrate or an inactivator for class C beta-lactamases; its k(2)/ K value was successfully calculated (8.7 x 10(5) - 7.0 x 10(6) M(-1) x s(-1)). In addition, k(3) values were determined for beta-lactamases from P. aeruginosa (2.3 x 10(-2) x s(-1)) and C. freundii (2.1 x 10(-1) x s(-1)). Even though these values could be calculated, transient inactivation as an enzyme reactivation reaction for all these enzymes was observed. These findings suggest the potential of cephem compounds as inhibitors of class C beta-lactamases.

Ceftizoxime↗
PubMed2002

Properties of extended-spectrum beta-lactamases constructed by site-directed mutagenesis.

Plasmids carrying three types of TEM-type extended-spectrum beta-lactamase (ESBL) genes, encoding TEM-3, TEM-5, and TEM-9, respectively, were constructed by site-directed mutagenesis. ESBL producers were prepared by transformation of Escherichia coli JM109 with a plasmid carrying one gene of either the three TEM types, an SHV-type, or a Toho-1 group gene. This strategy with the same vector and host strain can exclude the contribution of other factors to susceptibility, and is useful in Japan, where few TEM-type ESBL producers have been isolated. In vitro antibacterial activities of 23 beta-lactam antibiotics were tested against the ESBL producers by the agar dilution method, and the results were compared. The minimum inhibitory concentrations (MICs) of penicillins tested were more than 32 micro g/ml against both the parental RTEM and ESBL producers, but they were substantially decreased by a combination with beta-lactamase inhibitors. Compared with the MICs against the ESBL-nonproducing host strain, the MICs of the cephalosporins tested for the ESBL producers were increased more than eight times in most cases and in several cases soared to more than 2048 times against a Toho-1 ESBL producer. On the other hand, the MICs of carbapenem, cephamycin, and penem antibiotics were generally comparable to those against the host strain, and were increased by 32 times at most. Kinetic analysis revealed that extended-spectrum cephalosporins were hydrolyzed only slightly to moderately by the TEM-type ESBLs, while carbapenems and a cephamycin were scarcely hydrolyzed, and rather inhibited or inactivated the mutant enzymes.

Anti-Bacterial Agents↗
PubMed2002

Rapid pulsed-field gel electrophoresis technique for determination of genetic diversity of Serratia marcescens.

Seventeen Serratia marcescens strains were isolated from patients admitted to a hospital in the Tokyo metropolitan area. In order to study their genetic diversity, pulsed-field gel electrophoresis (PFGE) was performed. Clear bands were not observed by the standard PFGE technique following the instruction manual from the company. To obtain clear results, it was necessary to include some additional steps to the preparation of PFGE samples. We added an inactivation step for DNase using formaldehyde, and the bacterial strains were embedded in thinner plug molds than usual. These modifications were effective with all strains, and the complete PFGE pattern was obtained in the samples treated with formaldehyde and using thin plug molds. We established a rapid method to obtain a high-quality PFGE result for S. marcescens.

Electrophoresis, Gel, Pulsed-Field↗
PubMed2002

High frequency of erythromycin A resistance and distribution of mefE and ermB genes in clinical isolates of Streptococcus pneumoniae in Japan.

The ermB and mefE genes are important in terms of their responsibility for macrolide resistance in Streptococcus pneumoniae. We investigated the distribution of the ermB and mefE genes in erythromycin A-resistant S. pneumoniae isolated in our hospital during the period 1995-1998. All amoxicillin-low-susceptible isolates were considered to be resistant to erythromycin A. All isolates with resistance to erythromycin A (minimum inhibitory concentrations [MICs], > or =0.5 microg/ml) possessed ermB or mefE genes. The MICs of erythromycin A for most mefE-positive isolates ranged from 0.5 to 2 microg/ml. On the other hand, approximately 85% of ermB-positive isolates demonstrated high-level resistance to erythromycin A (MICs, > or =4 microg/ml) while the others showed low-level resistance (MICs, 0.5 to 2 microg/ml). In ermB-positive isolates with low-level resistance, high-level resistant mutants were selected with a frequency of 3.1 x 10(-6)-1.8 x 10(-3) on agar containing 4-32 MIC of erythromycin A, whereas in mefE-positive isolates, no high-level resistant mutants were detected. Mutants from ermB-positive isolates with low-level resistance showed reversibility and heterogeneity. Our data indicated a wide distribution of erythromycin A-resistant isolates with mefE or ermB genes among amoxicillin-low-susceptible S. pneumoniae in Japan. In addition, it is likely that ermB-positive isolates with low-level resistance show heterogeneous high-level resistance.

Amoxicillin↗
PubMed2002

Characterization of cefotaxime-resistant Escherichia coli isolates from a nosocomial outbreak at three geriatric hospitals.

Over a 22-month period, there was an unusual upsurge in the incidence of cefotaxime-resistant Escherichia coli among hospitalized patients in three geriatric hospitals in the same district. Sixteen highly cefotaxime-resistant strains were obtained from clinical specimens during the period January 1996 through October 1997. All strains were characterized by antibiotic resistance pattern analysis, the detection of the TEM- and Toho-type beta-lactamase or CTX-M-type beta-lactamase gene by polymerase chain reaction (PCR), plasmid profiling, Southern hybridization analysis, and pulsed-field gel electrophoresis (PFGE). Antibiotic resistance analysis showed that all strains were highly resistant to ampicillin, piperacillin, carbenicillin, cephaloridine, and cefotaxime; intermediately resistant to cefoxitin; moderately susceptible to moxalactam and ceftazidime; and susceptible to imipenem. Detailed analysis of beta-lactamase content revealed that all cefotaxime-resistant strains harbored a plasmid that mediated an extended-spectrum beta-lactamase of the Toho-type or CTX-M-type by PCR and Southern hybridization analysis. PCR detection showed that all the E. colistrains, except for strains TUM1023, TUM1101, TUM1227, and TUM1229, also possessed bla(TEM) genes. Furthermore, Southern hybridization analysis showed that all strains, except for TUM1102, gave a similar signal with the Toho probe. The PFGE profiles of the E. colistrains obtained with XbaI showed four patterns that correlated well with the plasmid profiles. The Dice value of 15 strains, including Toho-2 producer (TUM1083), for their PFGE patterns indicated a similarity of 80% or more. Our results suggest that 15 of the 17 Toho type beta-lactamase-producing E. coli strains (including strain TUM1083) studied belong to a single epidemic strain, while the other two strains are different from them, and the Toho-type or CTX-M-type beta-lactamase encoding gene may be acquired by plasmid conjugation or a mobile element.

Aged↗
PubMed2002

Macrolide-treated Pseudomonas aeruginosa induces paradoxical host responses in the lungs of mice and a high mortality rate.

OBJECTIVE: Accumulating data have demonstrated that macrolide antibiotics suppress Pseudomonas aeruginosa virulence, which may explain the efficacy of macrolides in clinical settings. We examined the virulence of macrolide-treated bacteria in vivo. METHODS: P. aeruginosa PAO-1 was grown for 24 h on agar containing sub-MIC antibiotics, and then mice were challenged intranasally with 10(7) cfu of bacteria. RESULTS AND CONCLUSIONS: The mortality rate of mice inoculated with bacteria grown in the presence of clarithromycin (10 mg/L), erythromycin (10 mg/L) or azithromycin (5 mg/L) was 80%, 80% and 100%, respectively. In contrast, none of the mice inoculated with non-treated bacteria or bacteria treated with other antibiotics died. Lung weight and protein concentration in bronchoalveolar lavage fluid (BALF) were significantly higher in the clarithromycin group between 3 and 9 h. Moreover, we detected higher levels of tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) in the BALF of these mice. These data demonstrate that macrolide-treated P. aeruginosa induced paradoxically strong responses, such as elevation of TNF-alpha, NO and permeability in the lungs.

Animals↗