一株分离自口腔的鼠李糖乳杆菌及其特性

目的 分离筛选出在维护口腔微生态平衡方面具有潜在益生特性的乳杆菌菌株。 方法 从健康志愿者的口腔样本中分离乳杆菌,采用生理生化和16S rDNA分子测序进行菌株鉴定,并检测其抑菌能力、凝集能力、表面疏水性以及对溶菌酶耐受性。 结果 筛选出1株鼠李糖乳杆菌LR863,对变形链球菌、戈登链球菌、牙龈卟啉单胞菌、具核梭杆菌和伴放线放线杆菌具有抑菌作用,经蛋白酶处理后其抑菌活性降低。同时鼠李糖乳杆菌LR863有较强的自凝集能力并对上述5株指示菌有共凝集效果,对二甲苯、氯仿和乙酸乙酯的疏水率依次为76.91%、87.46%和41.88%,能耐受2.0 mg/mL浓度的溶菌酶。 结论 鼠李糖乳杆菌LR863具有优良生物学特性,可作为口腔保健产品的候选益生菌株。     

Microbioassay of Antimicrobial Agents

A previously described agar-diffusion technique for microbioassay of antimicrobial agents has been modified to increase sensitivity of the technique and to extend the range of antimicrobial agents to which it is applicable. This microtechnique requires only 0.02 ml of an unknown test sample for assay, and is capable of measuring minute concentrations of antibiotics in buffer, serum, and urine. In some cases, up to a 20-fold increase in sensitivity is gained relative to other published standardized methods and the error of this method is less than +/-5%. Buffer standard curves have been established for this technique, concurrently with serum standard curves, yielding information on antimicrobial serum-binding and demonstrating linearity of the data points compared to the estimated regression line for the microconcentration ranges covered by this technique. This microassay technique is particularly well suited for pediatric research and for other investigations where sample volumes are small and quantitative accuracy is desired. Dilution of clinical samples to attain concentrations falling with the range of this assay makes the technique readily adaptable and suitable for general clinical pharmacological studies. The microassay technique has been standardized in buffer solutions and in normal human serum pools for the following antimicrobials: ampicillin, methicillin, penicillin G, oxacillin, cloxacillin, dicloxacillin, cephaloglycin, cephalexin, cephaloridine, cephalothin, erythromycin, rifamycin amino methyl piperazine, kanamycin, neomycin, streptomycin, colistin, polymyxin B, doxycycline, minocycline, oxytetracycline, tetracycline, and chloramphenicol.     

对镰刀菌有抗菌作用的硝基丙烷化合物

室内试验中测定了硝基丙烷化合物(药剂代号791224)对植物病原菌和镰刀菌的抗菌作用。791224对棉花枯萎病菌和小麦赤霉病菌菌丝生长的抑制作用明显优于其他供试植物病原菌。791224对所有供试镰刀菌均显示了优异的抗菌活性。791224浓度为5 ppm时,对供试的12种镰刀菌菌丝生长抑制效果平均在54.2—100%,对砖红镰刀菌的抑菌活性为100%,而相同浓度的多菌灵抑菌活性前者为0—27.3%,后者为0%,即低2.7—100倍。791224对由腐皮镰刀菌引起的国槐立枯病的防治效果也极为显著。     

Enrofloxacin treatment of long-tailed macaques with acute bacillary dysentery due to multiresistant Shigella flexneri IV.

Thirty-four cases of acute bacillary dysentery occurred within 90 days among macaques housed at the California Regional Primate Research Center. Cases were identified by depression, diarrhea with blood and leukocytic exudate, and/or leukocytosis with a left shift. Antimicrobial susceptibility testing of enteric isolates and plasmid profile analyses established an etiologic diagnosis of multiple antibiotic resistant Shigella flexneri IV infection. When standard therapies were invalidated by high frequencies of resistance among the isolates, therapy with enrofloxacin, a fluoroquinolone antimicrobial, was initiated to interrupt the epidemic. Serum concentrations of enrofloxacin and its primary metabolite ciprofloxacin were measured in selected cases. A serum concentration-time data analysis was performed to evaluate the oral enrofloxacin dose and dosing interval for nonfasted macaques. Once daily administration of 5 mg/kg enrofloxacin by gastric intubation produced 24-hour serum concentrations above the MICs for the Shigella isolates from this outbreak.     

Simultaneous determination of erythromycin propionate and base in human plasma by high-performance liquid chromatography-electrospray mass spectrometry

An analytical method for simultaneous determination of erythromycin propionate and its active metabolite, erythromycin base, in human plasma by high-performance liquid chromatography-electrospray mass spectrometry (HPLC-ESI-MS) was developed and validated. Roxithromycin was selected as the internal standard. The samples were directly injected after simple deproteinized procedure only. The separation was achieved on a Johnson Spherigel analytical column packed with 5 microm C18 silica, employing acetonitrile -0.1% formic acid aqueous solution (50:50) as mobile phase. The quantification of target compounds was obtained by using a selected ion monitoring (SIM) at m/z 790.7 for erythromycin propionate, m/z 734.7 for erythromycin base and m/z 837.8 for roxithromycin. The correlation coefficients of the calibration curves were better than 0.997 (n=6), in the ranges from 2 ng/ml to 1 microg/ml, and from 1 to 10 microg/ml for erythromycin propionate and base. The method can provide the necessary sensitivity, precision and accuracy to allow the simultaneous determination of both compounds in a patient's plasma following a single administration of erythromycin stinoprate capsule (500 mg erythromycin base equivalent).     

Erythromycin penetration into the cerebrospinal fluid of patients]

Permeability of erythromycin through the barrier of blood-cerebrospinal fluid in neurosurgical patients after its oral administration in a dose of 300-500 mg and intravenous administration in a dose of 200 mg was studied. The erythromycin was determined after the antibiotic single administration at intervals of 40 minutes to 6 hours. A total of 31 observations were performed. Low penetration of erythromycin into the cerebrospinal fluid of the patients was shown. The administration route (oral or intravenous) practically had no effect on the antibiotic penetration level into the subarachnoidal spaces. The highest liquor levels were observed within the period of 3 to 6 hours after the drug administration. The maximum index of penetration from the blood into the cerebrospinal fluid was about 10 per cent. The erythromycin penetration increased in cases with inflammatory changes in the meninges.     

Fowlicidin-3 is an alpha-helical cationic host defense peptide with potent antibacterial and lipopolysaccharide-neutralizing activities

Cathelicidins are an important family of cationic host defense peptides in vertebrates with both antimicrobial and immunomodulatory activities. Fowlicidin-1 and fowlicidin-2 are two newly identified chicken cathelicidins with potent antibacterial activities. Here we report structural and functional characterization of the putatively mature form of the third chicken cathelicidin, fowlicidin-3, for exploration of its therapeutic potential. NMR spectroscopy revealed that fowlicidin-3 comprises 27 amino-acid residues and adopts a predominantly alpha-helical structure extending from residue 9 to 25 with a slight kink induced by a glycine at position 17. It is highly potent against a broad range of Gram-negative and Gram-positive bacteria in vitro, including antibiotic-resistant strains, with minimum inhibitory concentrations in the range 1-2 microM. It kills bacteria quickly, permeabilizing cytoplasmic membranes immediately on coming into contact with them. Unlike many other host defense peptides with antimicrobial activities that are diminished by serum or salt, fowlicidin-3 retains bacteria-killing activities in the presence of 50% serum or physiological concentrations of salt. Furthermore, it is capable of suppressing lipopolysaccharide-induced expression of proinflammatory genes in mouse macrophage RAW264.7 cells, with nearly complete blockage at 10 microM. Fowlicidin-3 appears to be an excellent candidate for future development as a novel antimicrobial and antisepsis agent, particularly against antibiotic-resistant pathogens.     

Leishmania donovani: Oral efficacy and toxicity of formycin B in the infected hamster

Formycin B, a structural analog of inosine, was evaluated as an orally administrable antileishmanial agent. Against Leishmania donovani in hamsters, it achieved an 85–92% reduction in numbers of parasites in livers of infected animals after oral administration at 13 mg/kg/day for 4 days. Its efficacy by oral administration was approximately four to eight times that by intramuscular administration and four times that of the positive control drug Glucantime by intramuscular administration. The levels of formycin B in serum after the final oral administration of 26 mg/kg/day were 1.4 μg/ml at 1 hr and 0.3 μg/ml at 2 hr. The concentration in liver was greater (9.0 μg/ml at 1 hr) and declined more slowly. With this latter dosage or with 104 mg/kg/day there was no acute toxicity of formycin B to bone marrow or formed elements of the blood. The only statistically significant toxicity to the liver was a doubling of serum total bilirubin levels. Comparison of the in vivo efficacy of formycin B against L. donovani to the mild acute toxicity of the drug suggests that formycin B has potential as an oral agent against visceral leishmaniasis.     

Anti-anaerobic activity of serum from patients treated with tigecycline for skin/soft tissue infections

To gain additional data concerning the anti-anaerobic activity of tigecycline in serum, we analyzed blood samples from six patients with a complicated skin/soft tissue infection who were receiving IV tigecycline 50 mg every 12 h. Venous blood samples were obtained after multiple doses of tigecycline at 1, 6 and 12 h after the initiation of a 1 h IV infusion. Sera from these samples were tested to determine serum inhibitory and bactericidal activity over time against 4 anaerobic bacteria (Bacteroides fragilis, Peptoniphilus asaccharolyticus, Prevotella bivia and Finegoldia magna). An analysis of serum titers found that tigecycline exhibited early (1 h) and prolonged (12 h) inhibitory activity against each study isolate. Moreover, it provided bactericidal activity for 12 h against these strains with the exception of F. magna. Tigecycline was found to exhibit antibacterial activity at serum concentrations below the MICs of the anaerobic bacteria tested. This finding further supports that the antimicrobial activity of tigecycline can be greater than that suggested by the free fraction of drug and that serum appears to enhance this antibacterial activity.     

Investigations on the effect of antimicrobial drugs on platelet aggregation in vitro and ex vivo

The influence of ten betalactam antibiotics and ten other antibiotics on platelet aggregation induced by ADP or adrenaline was investigated in vitro. In concentrations of 900 mg/l most antimicrobial drugs exerted a moderate inhibition that was not seen in concentrations of 90 mg/l that better corresponded to therapeutic levels. The influence on the platelets of a single large intravenous dose was also tested using eight antimicrobial drugs, viz. benzylpenicillin, ampicillin, carbenicillin, piperacillin, cloxacillin, cefuroxime, cefotaxime and erythromycin. Each drug was given to five healthy volunteers but none caused any significant inhibition of platelet aggregation. The second wave of aggregation persisted after administration of the drugs and it was even seen after the administration of such a high dose as 10 g of carbenicillin.     

Isolation and Characterization of a New Antibiotic, ABBOTT 29119, from Streptomyces erythreus

A new antibiotic was isolated from fermentations of Streptomyces erythreus designed for erythromycin A production. Isolation of this compound was accomplished by use of ion-exchange chromatography and countercurrent distribution. It crystallized from methyl isobutyl ketone in colorless acicular plates which melted at 127 to 130 C. The empirical formula was C₄₂H₇₅NO₁₄ with a molecular weight of 820. Electrometric titration in 66% dimethylformamide showed an apparent pKa of 8.4. Nuclear magnetic resonance, infrared, and ultraviolet absorption indicated a close resemblance of the compound to known erythromycins, although its chromatographic behavior and solubility differed from those of the known erythromycins. Its antimicrobial spectrum was similar to erythromycin A, but the minimal inhibitory concentrations were much higher.     

Characterization of erythromycin resistance in Campylobacter coli and Campylobacter jejuni isolated from pig offal in New Zealand

AIMS: To determine the level and mechanism(s) of antimicrobial resistance in Campylobacter isolates obtained from human and environmental sources from South Canterbury, New Zealand. METHODS AND RESULTS: A total of 251 Campylobacter isolates were tested for susceptibility to ciprofloxacin, erythromycin, nalidixic acid and tetracycline using disc diffusion assays. Five pig offal isolates were observed to be highly erythromycin resistant, with minimal inhibitory concentrations determined to be >/=256 microg ml(-1). Nucleotide sequencing of the 23S ribosomal DNA (rDNA) in these resistant isolates identified an A --> G change at Escherichia coli position 2059 that has been previously implicated in erythromycin resistance in Campylobacter coli. Macrorestriction profiling using pulsed-field gel electrophoresis showed these isolates were nonclonal. CONCLUSIONS: The majority of Campylobacter isolates from South Canterbury remain sensitive to the most clinically relevant antimicrobial agents. Our results support other reports showing that specific variations in the 23S rDNA contribute to erythromycin resistance. SIGNIFICANCE AND IMPACTS OF THE STUDY: This study defines the baseline frequency of antimicrobial resistance associated with Campylobacter isolates from South Canterbury, and discusses the likely molecular mechanisms conferring erythromycin resistance in this organism. Resistance to erythromycin in these isolates is not linked to a dominant Campylobacter clone and has likely arisen independently in different genetic lines exposed to selective antimicrobial pressure.     

Effects of potassium ion concentrations on the antimicrobial activities of ionophores against ruminal anaerobes

The antimicrobial activities of monensin and lasalocid against representative strains of ruminal bacteria were evaluated in medium containing three different concentrations of potassium (1.3, 7.9, or 23.3 mM). The growth of Eubacterium ruminantium was inhibited by low concentrations of ionophores (less than or equal to 0.16 mg/liter), while the strain of Streptococcus bovis tested was resistant to high concentrations of ionophores (40 mg/liter) at all potassium concentrations tested. The MICs of the ionophores for strains of Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Ruminococcus flavefaciens and for one strain of Bacteroides ruminicola increased with increasing potassium concentrations in the medium. High concentrations of ionophores (40 mg/liter) decreased the maximum cell yields or increased the lag times or both in cultures of one strain of Bacteroides ruminicola and two strains of Selenomonas ruminantium but did not completely inhibit the growth of these organisms. Increased potassium concentrations in the medium (from 7.9 to 23.3 mM) decreased the lag times or increased the cell yields or both when these three strains were grown in ionophore-containing medium, while the activities of lasalocid and monensin against these organisms were enhanced in the medium containing low potassium concentrations (1.3 mM). The data from this study suggest that extracellular potassium concentrations may influence the antimicrobial activities of ionophores in the rumen.     

Therapy of Staphylococcal Infections in Monkeys. IV. Further Comparison of Triacetyloleandomycin and Erythromycins

Intravenous inoculation of a penicillin-resistant, phage type 80/81 staphylococcus caused lethal infection in 8 of 15 untreated monkeys. Daily intragastric administration of 50 mg/kg of triacetyloleandomycin, erythromycin estolate, and erythromycin ethylsuccinate was followed by mortalities of 0 of 16, 3 of 16, and 3 of 10, respectively. At dose levels of 25 and 12.5 mg/kg, none of 7 and 4 of 7 receiving triacetyloleandomycin and erythromycin estolate, respectively, died, as compared to 3 of 4 deaths in controls. In vitro sensitivity data and serum antibacterial levels would suggest that triacetyloleandomycin would be the least effective therapeutically. However, this prediction was not fulfilled in these studies of experimental infections in monkeys wherein triacetyloleandomycin was a very effective antimicrobial agent.     

Effects of potassium ion concentrations on the antimicrobial activities of ionophores against ruminal anaerobes.

The antimicrobial activities of monensin and lasalocid against representative strains of ruminal bacteria were evaluated in medium containing three different concentrations of potassium (1.3, 7.9, or 23.3 mM). The growth of Eubacterium ruminantium was inhibited by low concentrations of ionophores (less than or equal to 0.16 mg/liter), while the strain of Streptococcus bovis tested was resistant to high concentrations of ionophores (40 mg/liter) at all potassium concentrations tested. The MICs of the ionophores for strains of Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Ruminococcus flavefaciens and for one strain of Bacteroides ruminicola increased with increasing potassium concentrations in the medium. High concentrations of ionophores (40 mg/liter) decreased the maximum cell yields or increased the lag times or both in cultures of one strain of Bacteroides ruminicola and two strains of Selenomonas ruminantium but did not completely inhibit the growth of these organisms. Increased potassium concentrations in the medium (from 7.9 to 23.3 mM) decreased the lag times or increased the cell yields or both when these three strains were grown in ionophore-containing medium, while the activities of lasalocid and monensin against these organisms were enhanced in the medium containing low potassium concentrations (1.3 mM). The data from this study suggest that extracellular potassium concentrations may influence the antimicrobial activities of ionophores in the rumen.     

Serum Antibacterial Activity After Oral Suspensions and Capsules of Triacetyloleandomycin and Erythromycin Estolate

Comparison of serum antibacterial activity against a beta-hemolytic streptococcus and a penicillin-resistant staphylococcus was made in a cross-over study in volunteers after ingestion of oral suspensions and capsules of triacetyloleandomycin and erythromycin estolate. Oral suspensions yielded earlier peak titers, but ultimate peak titers and duration of activity were similar to those observed after ingestion of capsules. Antibacterial activity of serum against both organisms was consistently greater with both erythromycin estolate preparations than with the triacetyloleandomycin preparations. These in vitro data were comparable to observations made previously in monkeys infected with the same organisms, although comparative clinical efficacy in monkeys did not reflect these implied therapeutic differences.     

Antibacterial activity of 15-azasteroids alone and in combination with antibiotics.

A new class of 15-azasteroid analogues has been synthesized and tested for antimicrobial activity. The compounds 1, 10, 11, 11a-tetrahydro-7-methoxy-11a-methyl-2H-naphth (1,2-g) indol (methoxyimine) and 1,10,11,11a-tetrahydro-11a-methyl-2H-naphth (1,2-g) indol-7-ol (hydroxyimine) inhibit the growth of Bacillus subtillis and Escherichia coli at concentrations as low as 10-5 M. Addition of either compound to the growth medium casued a rapid inhibition in the transport of radioactive glucose, uracil and several amino acids. The inhibition of growth and substrate transport was reversed following removl of the steroid from the medium. The evidence is consistent with a site of steroid action at the cell periphery. Combining the methoxyimine with polyor circulin at subinhibitory concentrations produced greatly enhanced antimicrobial activity against Pseudomonas fluorescens. Similar action was observed against B. subtilis when the azasteroid was combined with vancomycin or chloramphenicol. The inhibitory action of other antibiotics such as penicillin or erythromycin was not affected by addition of the test compound. The results suggest formation of a molecular complex between the azasteroid and antibiotic which is responsible for the enhanced biological activity.     

Ceftazidime, a broad spectrum cephalosporin with activity against Ps. aeruginosa

Ceftazidime is one of the oximinoaminothiazolyl cephalosporins with resistance to most B-lactamases from gram-negative bacteria, and a very wide spectrum of activity including Ps. aeruginosa. MIC's of less than 0.1 mg/l are seen routinely against E. coli, K. pneumoniae, E. cloacae, Proteus spp. both indole positive and negative, Serratia sp., and Providence sp. The mean MIC against clinical isolates of Ps. aeruginosa is less than 2 mg/l. It is bactericidal at concentrations close to the MIC and its activity is unimpaired in the presence of serum. Ceftazidime is well distributed in the body, penetrating into all body fluids at concentrations excess of the MIC's of most pathogenic bacteria. It has a half-life of about 1.5 hours, is excreted almost exclusively by the kidney and is not bound to serum proteins. More than 12,000 patients have now been treated with the antibiotic, with an overall success rate of more than 93%.     

Effect of subinhibitory concentrations of antimicrobial agents (quinolones and macrolide) on the production of verotoxin by enterohemorrhagic Escherichia coli O157:H7.

In Japan, antimicrobial agent therapy for patients with diarrhea due to enterovirulent organisms including enterohemorrhagic Escherichia coli (EHEC) is common, and norfloxacin (NFLX), fosfomycin, and kanamycin are recommended for EHEC treatment by the Japanese Ministry of Health and Welfare. The aim of this study was to analyze the effects of antimicrobial agents which have been used or recommended for the treatment of EHEC on the production of verotoxin (VT) in vitro. Subinhibitory concentrations of quinolones, NFLX, sparofloxacin (SPFX), and grepafloxacin (GPFX) markedly stimulated the productions of VT1 and VT2. The macrolide azithromycin (AZM), erythromycin (EM), and clarithromycin (CAM) did not stimulate the production of VT at a wide range of concentrations. These in vitro results indicate that when quinolones are prescribed for a patient infected with EHEC, the concentration of antimicrobial agents used in vivo and the susceptibility of the EHEC strains against quinolones should be taken into consideration.     

Serum Bactericidal Activity of Trovafloxacin Against Selected Anaerobic Pathogens

Trovafloxacin is a fluoroquinolone antimicrobial with improved in vitro activity against many anaerobic bacteria. We investigated the serum bactericidal activity of trovafloxacin against isolates of Bacteroides fragilis, Bacteroides thetaiotaomicron, Clostridium perfringens, and Peptostreptococcus magnus using a broth microdilution method. All procedures were performed in an anaerobic chamber. A single 200 mg oral dose of trovafloxacin was administered to six healthy volunteers and serum samples were obtained at 0, 2, 4, 6, 8, 10, 12 and 24 h post-dose. Bactericidal activity of these samples demonstrated that at 2 h all samples showed bactericidal activity against all four isolates. Prolonged bactericidal activity (12 to 24 h) was observed against three of the four isolates. Bactericidal activity was not observed after the first sampling period for the B. thetaiotaomicron strain. In this pharmacodynamic model, we found that trovafloxacin provided serum bactericidal activity against several common anaerobic pathogens associated with clinical infections.