Surveillance of group B streptococcal toxic shock-like syndrome in nonpregnant adults and characterization of the strains in Japan.

Nine group B streptococci (GBS) strains were isolated from five toxic shock-like syndrome cases of nonpregnant adults in Japan from 2001 to 2005. All of them were identified as Streptococcus agalactiae. The serotypes of these strains were Ib, III, V, and VII. Pulsed-field gel electrophoresis revealed that the patterns of the strains isolated from the different patients were variable. Antimicrobial susceptibility tests showed that all of the strains were susceptible to penicillin G, ampicillin, cefotaxime, clindamycin, and telithromycin. One strain showed intermediate resistance to erythromycin.

Close correlation of streptococcal DNase B (sdaB) alleles with emm genotypes in Streptococcus pyogenes.

DNase B is a major nuclease and a possible virulence factor in Streptococcus pyogenes. The allelic diversity of streptococcal DNase B (sdaB) gene was investigated in 83 strains with 14 emm genotypes. Of the 15 alleles identified, 11 alleles carried only synonymous nucleotide substitutions. On the other hand, 4 alleles had a non-synonymous substitution other than synonymous substitutions, resulting in the substitution of a single amino acid. The distribution of each allele was generally emm genotype-specific. Only sdaB7 was found in both emm2 and emm4. The promoter region was highly conserved and DNase B protein was similarly expressed in all alleles.

Antimicrobial susceptibility survey of Streptococcus pyogenes isolated in Japan from patients with severe invasive group A streptococcal infections.

We assessed antimicrobial susceptibility against 211 Streptococcus pyogenes strains isolated from patients with severe invasive group A streptococcal infections. Overall, 3.8, 1.4, 1.4, and 0.5% of the isolates were resistant to erythromycin, clindamycin, telithromycin, and ciprofloxacin, respectively, and 10.4% had intermediate resistance to ciprofloxacin. All isolates were susceptible to ampicillin and cefotaxime.

Molecular mechanisms of high level tetracycline-resistance in group A streptococcal isolates, T serotypes 4 and 11.

The molecular mechanism of high level tetracycline resistance in T serotypes 4 and 11 group A streptococcal (GAS) isolates was examined in 61 tetracycline-resistant isolates in Japan. PCR and sequencing analyses revealed that the T serotype/emm genotype, T4/4 isolates carried tet(O) genes, which were genetically homogenous. The T11/11 and T11/89 isolates carried different subtypes of tet(M) genes, which were present on transposons Tn916 and Tn1545, respectively. In addition, these T11 isolates may have obtained the tet(M) gene after the 1990s, because resistance to tetracycline in T11 isolates was rarely found before then. These results strongly suggested that the T4 and T11 GAS isolates acquired tetracycline-resistance via different molecular mechanisms.

Contamination of environmental surfaces by Staphylococcus aureus in a dermatological ward and its preventive measures.

We investigated contamination of environmental surfaces by Staphylococcus aureus from April 1 to the end of June in 2002 in the dermatological ward (37 beds) of a university hospital. For surfaces contaminated by high levels of S. aureus, disinfection methods were evaluated. 100-10(5) colony forming units (cfu) of methicillin-resistant S. aureus (MRSA) or methicillin-sensitive S. aureus (MSSA) were detected on items such as an immersion bathtub (examined area, about 900 cm2), foot washbowl, stretcher for an immersion bath, and chair for the shower. After disinfection, no S. aureus was detected on smooth surfaces such as the immersion bathtub and foot washbowl; however, S. aureus was detected even after disinfection on porous surfaces made of sponge-like materials (polyethylene foam) such as the stretcher for the immersion bath and the shower chair. Scanning electron microscopy of the porous surfaces showed formation of a large amount of coccus and bacillus biofilms on the walls of pores in the multi-pore structure. Material that is porous should not be used in patient care settings because it is not possible to disinfect it properly.

In vitro bactericidal activity of antimicrobial agents against enterohaemorrhagic Escherichia coli.

OBJECTIVES: In vitro bactericidal activity of four antimicrobial agents was determined against nine strains of enterohaemorrhagic Escherichia coli. METHODS: Pulsed-field gel electrophoresis was carried out with the Bio-Rad Gene Path system. Each antimicrobial agent was added to logarithmic phase of enterohaemorrhagic E. coli (four strains of E. coli O157:H7, two of E. coli O26, two of E. coli O111, and one of E. coli O165) in broth to obtain a concentration of 10 or 50 mg/L, and viable cells were counted after 1, 2, 6 and 24 h. RESULTS: All nine strains were confirmed to differ in their DNA pattern by pulsed-field gel electrophoresis. Norfloxacin at concentrations of 10 and 50 mg/L had bactericidal effects on all nine strains of enterohaemorrhagic E. coli. However, cefoperazone, kanamycin and fosfomycin had no bactericidal effects on some strains. In particular, after addition of 10 mg/L fosfomycin or kanamycin, four of the nine strains showed proliferation. CONCLUSIONS: Norfloxacin had marked bactericidal effects on enterohaemorrhagic E. coli. This information could be of value in planning randomized clinical trials of antimicrobial agents as treatment for enterohaemorrhagic E. coli infection.

In vitro effects of combinations of antipseudomonal agents against seven strains of multidrug-resistant Pseudomonas aeruginosa.

OBJECTIVES: The aim of this study was to evaluate the combined effects of antibiotic combinations by agar incorporation inhibitory tests and by time-kill tests on seven geographically and epidemiologically distinct isolates of multidrug-resistant Pseudomonas aeruginosa. All seven strains were resistant to piperacillin, meropenem, ceftazidime, cefoperazone-sulbactam, aztreonam, amikacin and ciprofloxacin. METHODS: Strains were distinguished by pulsed-field gel electrophoresis after DNA extraction and restriction with SpeI. MICs of the seven antibiotics listed above were determined by agar dilution. The effect of combinations of these agents was determined by agar incorporation tests and by time-kill studies. RESULTS: Among the two-drug combinations, the combination aztreonam and amikacin was the most effective, inhibiting proliferation in five of the seven strains. Among the three-drug combinations, the combinations of piperacillin, ceftazidime and amikacin, and that of ceftazidime, aztreonam and amikacin were the most effective, inhibiting proliferation in all seven strains. In the killing tests, the three-drug combination of ceftazidime, aztreonam and amikacin was the most effective. This three-drug combination had bacteriostatic effects on all seven strains 2, 4, 6 and 24 h after drug addition, synergic effects on 2-3 strains and bactericidal effects on 1-2 strains after 4, 6 and 24 h. CONCLUSIONS: The three-drug combination of ceftazidime, aztreonam and amikacin may be effective against P. aeruginosa resistant to all commonly used antipseudomonal drugs, and deserves further study.

Evidence of pharmacologic preconditioning during PTCA by intravenous pretreatment with ATP-sensitive K+ channel opener nicorandil.

BACKGROUND: It is not known whether pretreatment with nicorandil, an ATP-sensitive K+ channel (K(ATP)channel) opener, induces a preconditioning effect independent of increased collateral recruitment. METHODS: Forty-four patients with angina who underwent percutaneous transluminal coronary angioplasty (PTCA) to proximal left anterior descending artery (LAD) stenosis were randomly allocated for pretreatment with an intravenous injection of 80 g/kg nicorandil 5 min before initial ballooning (n=22) or saline (n=22). 99mTc tetrofosmin was injected during balloon inflation, quantitative analysis of occlusion images by SPECT was conducted, and the defect severity score (SS) was calculated. An ECG was recorded during the 2-min inflation to calculate the sum of ST elevation (sigmaST). RESULTS: SigmaST levels were significantly reduced in patients with nicorandil pretreatment compared with control patients (control:1.89+/-0.85 mV nicorandil:1.24+/-0.57 mV, p=0.0052). However, no difference was observed in defect severity (control: 79.0+/-32.5, nicorandil: 98.7+/-48.9 ns). A close correlation was observed between SS and sigmaST in both groups (nicorandil group R(2)=0.505, control group R(2)=0.599). A multivariate regression model demonstrated that both defect severity (p<0.0001) and pretreatment with nicorandil (p<0.001) were significantly related to the level of sigmaST, suggesting a cellular protective effect against ischaemia by nicorandil, independent of myocardial blood flow. CONCLUSION: Nicorandil pretreatment resulted in the induction of myocardial preconditioning independent of the severity of ischaemia.

Evidence of a cellular protective effect by antecedent angina independent of collateral flow recruitment during coronary angioplasty in humans.

The main aim of this study was to elucidate whether the beneficial effect of antecedent angina is a cellular protective effect or the result of an increase of collateral flow. Of 42 patients with angina who underwent percutaneous transluminal coronary angioplasty (PTCA) for proximal left anterior descending artery (LAD) stenosis, 22 had experienced antecedent anginal pain (AP) within 7 days prior to PTCA. 99mTc-sestamibi was injected during balloon inflation, and quantitative analysis of ischemic severity during coronary occlusion was calculated (SS). An electrocardiogram was recorded during ballooning to calculate the sum of ST elevation (sumST). SumST was significantly reduced in patients with AP compared with patients without AP (1.88+/-0.89 mV vs 1.18+/-0.74 mV, p=0.0088); however, no difference was observed in defect severity. A close correlation was observed between SS and sumST in both groups. The multivariate regression model demonstrated that both a large SS (p<0.0001) and the absence of preceding AP (p=0.001) were significantly related to the elevation of sumST. Recent angina can render the myocardium more resistant to subsequent ischemia during angioplasty and is true preconditioning rather than simply an increase of flow.

[Epidemiological and bacteriological investigation of enterohemorrhagic Escherichia coli infection in the Chugoku-Shikoku area].

We investigated the occurring tendency of enterohemorrhagic Escherichia coli (EHEC) infection in the prefectural and municipal public health institutes in the Chugoku-Shikoku area from 1996 to 1999, and the bacteriological characteristics of EHEC isolated from these cases. Consequently, epidemiological analysis of the EHEC infection in this district was performed. 22 outbreaks in the various facilities showed the tendency occurred in infants and aged groups, and the serotypes of EHEC isolated from these outbreaks were O26, O111 etc. as well as O157. In 4 cases, EHEC were isolated from specimens of buckwheat noodles, salad, sand box, and goat feces, and these were determined as the source of infection. In 898 sporadic cases, including familial infection, the EHEC isolates were classified into 24 serotypes, and the genotypes of EHEC O157:H7 isolates by pulsed-field gel electrophoresis (PFGE) also varied. Moreover, since many asymptomatic carriers were detected in the adult group with familial infection, the existence of healthy carriers is as important as the source of infection. The drug-resistance test of EHEC isolates showed that 24% of the 924 isolates were resistant to drugs.

In vitro susceptibility of four serotypes of enterohaemorrhagic Escherichia coli to antimicrobial agents.

We evaluated the in vitro susceptibility of four serotypes of enterohaemorrhagic Escherichia coli (E. coli 026, E. coli O111, E. coli O157, and E. coli O165) with diverse DNA patterns to antimicrobial agents. The minimum inhibitory concentrations (MIC) determined in a total of 83 strains using Mueller-Hinton agar under aerobic and anaerobic conditions were 0.015-0.12 microg/ml for ciprofloxacin, 0.06-1 microg/ml for norfloxacin, 2-64 microg/ml for fosfomycin without glucose-6-phosphate (G-6-P), 0.25-32 microg/ml for fosfomycin with G-6-P, 2- > or = 256 microg/ml for kanamycin, 0.125-2 microg/ml for cefoperazone, and 0.06-1 microg/ml for ceftazidime. The MIC of ciprofloxacin, norfloxacin, cefoperazone, and ceftazidime were low in all strains examined.

Validation of collateral fractional flow reserve by myocardial perfusion imaging.

BACKGROUND: Collateral fractional flow reserve (FFR(coll)) is an index to quantify collateral blood flow, derived from coronary pressure measurements. Although well defined theoretically, its direct validation by myocardial perfusion imaging has not been established so far. Validating this index by myocardial perfusion imaging is the main aim of this study. METHODS AND RESULTS: Twenty-four consecutive patients with stable angina and single left anterior descending artery stenosis underwent simultaneous measurement of aortic pressure (P(a)), coronary wedge pressure (P(w)), and central venous pressure (P(v)) during balloon inflation. FFR(coll) was calculated and compared with the extent and severity of the defect during coronary occlusion using (99m)Tc-sestamibi imaging at balloon inflation of the respective coronary artery. Although the pressure-derived collateral indexes (P(w), P(w)/P(a), and FFR(coll)) ranged widely, they were closely correlated with extent and severity scores of the nuclear occlusion images and superior to the ECG for that purpose. Of all parameters, FFR(coll) correlated best with the severity score at imaging (r=-0.88), followed by the P(w)/P(a) ratio (r=-0.74) or P(w) alone (r=-0.69). CONCLUSIONS: FFR(coll), calculated from coronary pressure during balloon occlusion, is highly correlated with the extent and severity of the defect at myocardial perfusion of the territory of the occluded artery and can be used for quantitative assessment of collateral blood flow in conscious humans.