In vitro Activity of Gatifloxacin Against 238 Strains of Anaerobic Bacteria

The activity of gatifloxacin, a new 8-methoxy-fluoroquinolone, was tested against 208 pulmonary pathogens and against an additional 30 isolates of the Bacteroides fragilis group. Pulmonary isolates were from patients with documented anaerobic pleuropulmonary infections and were obtained by appropriate sampling methods. MICs were determined using the NCCLS-approved Wadsworth brucella laked blood agar method and compared to those of clindamycin, imipenem, metronidazole and trovafloxacin. Breakpoints used to define susceptible and [resistant] categories were (in μg/ml): Clindamycin-2, imipenem-4, metronidazole 8 and trovafloxacin. No breakpoint has been defined for gatifloxacin. Gatifloxacin inhibited 99% of all anaerobes tested at 4 μg/ml and 97% of all strains at 2 μg/ml. One strain of B. fragilis was resistant to gatifloxacin at 4 μg/ml; all strains of other B. fragilis group species were susceptible. One strain of Peptostreptococcus sp. was resistant to both gatifloxacin and trovafloxacin (MIC >4 μg/ml). All other strains were susceptible to all agents at ≤μg/ml. All of the non-sporeforming Gram-positive rods were susceptible to gatifloxacin at ≤μg/ml (three strains had an MIC of 4 μg/ml). Trovafloxacin had MICs of 4 μg/ml for two strains, and an MIC of 8 μg/ml for one strain. Five percent of B. fragilis, 21% of other B. fragilis group species and 20% of Clostridium species (other than C. difficile, C. perfringens or C. ramosum) were resistant to clindamycin. No imipenem resistant isolates were found in this study. Gatifloxacin appears to have excellentin vitro activity against pulmonary isolates of anaerobes and very good activity against strains of the B. fragilis group.     

双歧杆菌的粘附特性及其对肠道致病菌的体外拮抗作用

本文采用体外细胞培养法, 从实验室现有的20株不同生境来源的双歧杆菌中筛选具有较强粘附能力的菌株, 并通过混合培养和牛津杯方法, 研究了具有粘附特性的双歧杆菌对肠道致病菌的体外拮抗作用。结果显示, 长寿老人源菌株A03和I06的粘附能力最强, 其菌液对金黄色葡萄球菌及大肠杆菌均具有显著的抑制性, 但是菌体及中和后的发酵液均没有抑菌性, 说明受试菌主要通过其代谢产物中的有机酸来发挥其抑菌性能; 此外, 通过分析比较受试菌和肠道致病菌分别与Caco-2细胞粘附后释放的乳酸脱氢酶量, 证实双歧杆菌与致病菌对细胞的作用具有本质上的区别, 双歧杆菌的粘附能减缓致病菌对细胞所造成的损害。     

Comparison of the Activity of Meropenem and Imipenem Against Anaerobic Bacteria in Bulgaria

The in vitro activities of meropenem and imipenem were compared against 154 clinical isolates of anaerobic bacteria representing 23 species of 10 genera. The NCCLS-recommended agar dilution method with Brucella agar from the Wadsworth Anaerobic Laboratory was used. Meropenem proved to be more active than imipenem with an MIC range of ≤0.125–4 μg/mL, MIC₅₀=0.25 μg/mL, MIC₉₀=1 μg/mL with 100% of strains susceptible at the breakpoint=4 μg/mL. Imipenem showed a lower activity with an MIC range of ≤0.125 to 16 μg/mL, MIC₅₀of 2 μg/mL and MIC₉₀of 4 μg/mL with 10% of the strains not inhibited at this concentration. Ninety-six per cent were susceptible at 8 μg/mL and 100% at 16 μg/mL. The MIC of both antibiotics (especially of imipenem) were higher for the Bacteroides fragilis group than for the rest of the Gram-negative organism higher still than the Gram-positive anaerobes.     

In Vitro Activity of Doxycycline Against Bacteria from Clinical Material

Doxycycline (alpha-6-deoxy-oxytetracycline) was tested against various bacteria of recent clinical origin with 30-mug discs. The antibiotic susceptibility of these bacteria to commonly used antimicrobial agents was also established. Those bacteria which responded with equivocal zones of inhibition about the tetracycline compounds were tested by the tube dilution technique. Staphylococci and enterococci consistently displayed greater in vitro susceptibility to doxycycline than to tetracycline or demethylchlortetracycline.     

Maintenance of Laboratory Strains of Obligately Anaerobic Rumen Bacteria

Cultures of rumen bacteria can be stored at −20°C for at least 2 years in a liquid medium containing 20% glycerol. Thawing, sampling, and refreezing do not significantly affect viability.     

In Situ Activity and Spatial Organization of Anaerobic Ammonium-Oxidizing (Anammox) Bacteria in Biofilms

We investigated autotrophic anaerobic ammonium-oxidizing (anammox) biofilms for their spatial organization, community composition, and in situ activities by using molecular biological techniques combined with microelectrodes. Results of phylogenetic analysis and fluorescence in situ hybridization (FISH) revealed that “Brocadia”-like anammox bacteria that hybridized with the Amx820 probe dominated, with 60 to 92% of total bacteria in the upper part (<1,000 μm) of the biofilm, where high anammox activity was mainly detected with microelectrodes. The relative abundance of anammox bacteria decreased along the flow direction of the reactor. FISH results also indicated that Nitrosomonas-, Nitrosospira-, and Nitrosococcus-like aerobic ammonia-oxidizing bacteria (AOB) and Nitrospira-like nitrite-oxidizing bacteria (NOB) coexisted with anammox bacteria and accounted for 13 to 21% of total bacteria in the biofilms. Microelectrode measurements at three points along the anammox reactor revealed that the NH₄⁺ and NO₂⁻ consumption rates decreased from 0.68 and 0.64 μmol cm⁻² h⁻¹ at P2 (the second port, 170 mm from the inlet port) to 0.30 and 0.35 μmol cm⁻² h⁻¹ at P3 (the third port, 205 mm from the inlet port), respectively. No anammox activity was detected at P4 (the fourth port, 240 mm from the inlet port), even though sufficient amounts of NH₄⁺ and NO₂⁻ and a high abundance of anammox bacteria were still present. This result could be explained by the inhibitory effect of organic compounds derived from biomass decay and/or produced by anammox and coexisting bacteria in the upper parts of the biofilm and in the upstream part of the reactor. The anammox activities in the biofilm determined by microelectrodes reflected the overall reactor performance. The several groups of aerobic AOB lineages, Nitrospira-like NOB, and Betaproteobacteria coexisting in the anammox biofilm might consume a trace amount of O₂ or organic compounds, which consequently established suitable microenvironments for anammox bacteria.     

中药抗厌氧菌的系列研究：Ⅲ.大黄抗厌氧菌的实验研究

本研究进一步用大黄水煎液,大黄醇提物和大黄蒽醌衍生物(芦荟大黄素、大黄酸和大黄素),对临床分离的100株厌氧菌进行MIC测定,并对部分菌株进行MBC测定和亚抑菌浓度(Sub-MIC)下细菌形态观察。结果表明,大黄水煎液在1600μg/ml浓度时能抑制74％厌氧菌生长,大黄醇提物的MIC约为水煎液的1/15。三种蒽醌衍生物在8μg/ml时能抑制76～91％厌氧菌生长,这与国际公认的抗厌氧菌药甲硝唑相近。对部分菌株的MBC测定表明,大黄的MBC要大于MIC几倍以上,说明大黄抗厌氧菌主要是抑菌不是杀菌。从Sub-MIC下厌氧菌形态改变提示,大黄主要是抑制细胞壁的合成。     

Taurine-Sulfur Assimilation and Taurine-Pyruvate Aminotransferase Activity in Anaerobic Bacteria

We demonstrated the ability of strictly fermentative, as well as facultatively fermentative, bacteria to assimilate sulfonate sulfur for growth. Taurine (2-aminoethanesulfonate) can be utilized by Clostridium pasteurianum C1 but does not support fermentative growth of two Klebsiella spp. and two different Clostridium spp. However, the latter are able to assimilate the sulfur of a variety of other sulfonates (e.g., cysteate, 3-sulfopyruvate, and 3-sulfolactate) anaerobically. A novel taurine-pyruvate aminotransferase activity was detected in cell extracts of C. pasteurianum C1 grown with taurine as the sole sulfur source. This activity was not detected in extracts of other bacteria examined, in C. pasteurianum C1 grown with sulfate or sulfite as the sulfur source, or in a Klebsiella isolate assimilating taurine-sulfur by aerobic respiration. More common aminotransferase activities (e.g., with aspartate or glutamate as the amino donor and pyruvate, oxalacetate, or (alpha)-ketoglutarate as the amino acceptor) were present, no matter what sulfur source was used for growth. Partial characterization of the taurine-pyruvate aminotransferase revealed an optimal temperature of 37(deg)C and a broad optimal pH range of 7.5 to 9.5.     

拮抗菌株抑菌活性的保藏试验研究

研究不同保藏介质、温度和时间的综合因素对B-298菌株活性的影响。为生产和研究提供能保持该菌株抑菌活性的适宜保藏方法。试验结果表明：介质、温度、时间的交互作用对菌株细胞存活率和代谢产物拮抗效应的影响都存在显著性差异;细胞存活率和拮抗效应与保藏时间呈反比;菌株保藏680 d,应用甘油超低温保藏法,菌株细胞存活率和抑菌活性最高,而采用斜面常温保藏,细胞存活率和抑菌活性最低。     

抗厌氧菌中草药的系列研究：Ⅰ,抗厌氧菌中草药的筛选

目前治疗厌氧菌感染的药物不够理想,仍需发掘新药。根据文献选出抗感染中草药389种,用水、乙醇和石油醚三种溶剂,分别提取和制备成含生药1g/ml的药液,对临床常见的脆弱类杆菌等12种厌氧菌进行平板打孔法的抑菌试验。结果显示诃子、茴香根、穿心莲、黄连、肉桂、大黄、五味子、木通等53种中草药的1～3种提取液能对二种以上的厌氧菌有直径20mm以上的抑菌环。反复试验显示肉佳、大黄、五味子、木通能稳定地对4种以上的厌氧菌有20mm以上的抑菌环。作者认为平板打孔法是筛选中草药抗菌作用的简便方法,并准备对选出的中草药作进一步研究。     

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.     

Antimicrobial Activity of Monoketone Curcuminoids Against Cariogenic Bacteria

We evaluated the antimicrobial activity of 25 monoketone curcuminoids (MKCs) against a representative panel of cariogenic bacteria in terms of their minimum inhibitory concentration (MIC) values. Curcumin A ( 10 ) displayed promising activity against Streptococcus mutans (MIC = 50 μg/ml) and Streptococcus mitis (MIC = 50 μg/ml) as well as moderate activity against S. sanguinis (MIC = 100 μg/ml), Lactobacillus casei (MIC = 100 μg/ml), and Streptococcus salivarius (MIC = 200 μg/ml). Results indicated higher activity of compound 10 than that of its bis‐β‐diketone analog. Additionally, compounds 3a (1,5‐bis(4‐methylphenyl)pentan‐3‐one) and 7b (1,5‐bis(4‐bromophenyl)pentan‐3‐ol) were moderately active against S. mitis (MIC = 100 μg/ml) and S. salivarus (MIC = 200 μg/ml).     

Antiviral Activity of a bis-Benzimidazole Against Experimental Rhinovirus Infections in Chimpanzees

The marked antiviral activity of (S,S-1,2-bis(5-methoxy-2-benzimidazolyl)-1,2-ethanediol (Abbott 36683) against rhinoviruses in tissue culture warranted investigation of its antiviral activity in vivo. Antiviral levels in mouse sera were attained with an oral dose as small as 10 mg/kg and detectable antiviral levels of drug were also found in lung, liver, kidney, intestinal contents, and urine of mice given a single 300 mg/kg oral dose. Antiviral serum levels were also obtained when monkeys were given a single oral dose of Abbott 36683. Six chimpanzees were infected with 100 median tissue culture infective dose units (TCID(50)) of rhinovirus 30. Three of the animals were treated with Abbott 36683, 100 mg/kg daily for 4 consecutive days. Virus shedding occurred in the infected controls but could not be demonstrated in the treated animals from postinfection days 1 to 8. Two of the treated animals did, however, shed virus on day 9. The compound was retested in chimpanzees at dosage levels of 15 and 50 mg/kg daily for 4 days. Each animal was challenged with 100 TCID(50) of rhinovirus 49. Partial protection was obtained. In a third trial, a single 100 mg/kg dose of the compound was administered to chimpanzees infected with rhinovirus 44. Virus was isolated from all throat smears taken from treated animals, indicating that at the lowest drug level no protection occurred.     

Methacrylate-Reducing Activity of Anaerobic Bacteria Anaeromyxobacter dehalogenans and Denitrovibrio acetiphilus

Microbiology - Periplasmic methacrylate-reducing activity was shown for anaerobic acetate-oxidizing gram-negative bacteria Anaeromyxobacter dehalogenans 2CP-1Т (class Deltaproteobacteria) and...     

Anaerobic Ammonia-Oxidizing Bacteria and Related Activity in Baltimore Inner Harbor Sediment

The discovery of bacteria capable of anaerobic ammonia oxidation (anammox) has generated interest in understanding the activity, diversity, and distribution of these bacteria in the environment. In this study anammox activity in sediment samples obtained from the Inner Harbor of Baltimore, Md., was detected by ¹⁵N tracer assays. Anammox-specific oligonucleotide primer sets were used to screen a Planctomycetales-specific 16S rRNA gene library generated from sediment DNA preparations, and four new anammox bacterial sequences were identified. Three of these sequences form a cohesive new branch of the anammox group, and the fourth sequence branches separately from this group. Denaturing gradient gel electrophoresis analysis of sediment incubated with anammox-specific media confirmed the presence of the four anammox-related 16S rRNA gene sequences. Evidence for the presence of anammox bacteria in Inner Harbor sediment was also obtained by using an anammox-specific probe in fluorescence in situ hybridization studies. To our knowledge, this is the first report of anammox activity and related bacterial 16S rRNA gene sequences from the Chesapeake Bay basin area, and the results suggest that this pathway plays an important role in the nitrogen cycle of this estuarine environment. Furthermore, the presence of these bacteria and their activity in sediment strengthen the contention that anammox-related Plactomycetales are globally distributed.     

Bactericidal Activity and Synergy Studies of Peptide AP-CECT7121 Against Multi-resistant Bacteria Isolated from Human and Animal Soft Tissue Infections

AP-CECT7121 is an antimicrobial peptide, produced by Enterococcus faecalis CECT7121, with bactericidal activity against Gram-positive bacteria. The aim of this study was to evaluate the bactericidal activity of AP-CECT7121, alone and with gentamicin, against multi-resistant bacteria isolated from human and animals with soft tissue infections. During the period 2014–2015, bacterial strains producing human and animal soft tissue infections were studied. Samples from patients attended at a general hospital and cattle from four dairies in the Province of Buenos Aires (Argentina) were included. Twenty-two methicillin-resistant Staphylococcus aureus (11, human blood samples; 11, cow milk) and five vancomycin-resistant Ent. faecium strains isolated from four mastitic dairy cows were tested. AP-CECT7121 (12 mg/L) potency was assessed by time-kill curves alone or with sub-inhibitory concentrations of gentamicin. All staphylococcal strains were susceptible to gentamicin; enterococci did not show high-level gentamicin resistance. Colony counts were carried out at 0, 2, 4, 8, and 24 h of incubation. AP-CECT7121 showed bactericidal activity against all the enterococcal strains. In addition, AP-CECT7121 had a bactericidal effect on most staphylococci (16/22). Early AP-CECT7121/gentamicin synergy (4–8 h) for all staphylococci was detected. At 24 h, synergy (19/22) and indifference (3/22) were observed. Synergy with gentamicin was detected for staphylococci. AP-CECT7121 constitutes an attractive candidate for its use as a natural therapeutic tool for the treatment of infections produced by multi-resistant Staph. aureus and vancomycin-resistant Ent. faecium isolated from humans and animals.     

Antifungal Activity of Sodium Bicarbonate Against Fungal Agents Causing Superficial Infections

Although sodium bicarbonate—NaHCO₃ (SB) has many domestic and medical, traditional and empirical uses, only little scientific documentation of its activity is available. The aims of this study were to investigate the antifungal activity of SB on the three fungal groups (yeasts, dermatophytes and molds) responsible for human skin and nail infections. We first evaluated the in vitro antifungal activity of SB on 70 fungal strains isolated from skin and nail infections: 40 dermatophytes, 18 yeasts and 12 molds. A concentration of 10 g/L SB inhibited the growth of 80 % of all the fungal isolates tested on Sabouraud dextrose agar. The minimal inhibitory concentration 90 (MIC90) of SB measured on Sabouraud dextrose agar, Sabouraud dextrose broth and potato dextrose broth was 5 g/L for the yeasts, 20 g/L for the dermatophytes and 40 g/L for the molds. In a second step, we prospectively evaluated the ex vivo antifungal activity of SB on 24 infected (15 dermatophytes, 7 yeasts and 2 molds) clinical specimens (15 nails and 9 skin scrapings). The fungal growth was completely inhibited for 19 (79 %) specimens and reduced for 4 (17 %) specimens after 7 days of incubation on Sabouraud dextrose–chloramphenicol agar supplemented with 10 g/L of SB as compared to Sabouraud dextrose–chloramphenicol agar without SB. In conclusion, we documented the antifungal activity of SB on the most common agents of cutaneous fungal infection and onychomycosis, and we specified the effective concentrations for the different groups of pathogenic fungi. The mechanism of action of SB has yet to be explored.     

Antagonistic Activity of Five Myrothecium Species Against Fungi and Bacteria in Vitro

Antagonistic activity of 69 Myrothecium isolates belonging to M. carmichaelü, M. cinctum, M. roridum, M. tongaense and M. verrucaria against six soil-borne plant pathogenic fungi was investigated by using the streak method. Results clearly showed that M. carmichaelü is a strong antibiont having a very high degree of antifungal efficacy. M. cinctum and M. tongaense isolates were found to have an antagonistic activity either through antibiosis or mycoparasitism or both against the test fungi. M. roridum and M. verrucaria isolates also possessed both kinds of activities. After this first screening (of all Myrothecium isolates), one isolate from each species exhibiting the highest degree of antagonistic activity was selected for further studies. Inhibitory effects of culture filtrates of these representative isolates on the mycelial growth of the test fungi were investigated by incorporating them into PDA at a dilution of 1:8. M. carmichaelü was the most and M. cinctum the least effective species under assay. Moreover, culture filtrates and mycelium extracts of the selected isolates were found to have both antifungal and antibacterial properties using the agar-well method. Among the test fungi, Sclerotinia sclerotiorum proved to be generally the most, and Pythium debaryanum the least sensitive to the antibiotic effects. M. cinctum showed the widest antibacterial spectrum inhibiting five bacterial species except for Pseudomonas syringae Pv. Phaseolicola. Additionally, the observations using light and scanning electron microscopy clearly demonstrated that all of the five Myrothecium species were able to parasitize all of the tested fungi.