Number Of Live Bacteria Research Articles

Mixed culture of probiotics on a solid-state medium: An efficient method to produce an affordable probiotic feed additive

The overuse and abuse of antibiotics in animal husbandry is an ongoing problem. While probiotics could be an alternative, their effectiveness, stability and production cost are key factors that need to be addressed first. This study used a mixed culture of Bifidobacterium bifidum, Clostridium butyricum, Bacillus subtilis and Bacillus licheniformis on a simple and inexpensive solid-state medium generated by pouring a liquid MRS medium, which was designed to favor the dense growth of lactobacilli, onto wheat bran at a ratio of 1:2 by weight. Using this method, we achieved a very high number of live bacteria (NLB), at 3.93 × 1014 CFU/g, without the need for expensive anaerobic equipment. The mixed culture thus achieved striking results that were up to 10,000 times better than the pure culture and did not require special anaerobic equipment. A real-time PCR analysis demonstrated that the shares of the four strains in the mixed culture probiotics (MCPs) were 2, 17, 46, and 35%, respectively, which indicates that the fermentation product contained an uneven distribution of the four probiotic target bacteria. The MCPs possessed good storage stability at room temperature, and the NLB was greater than 106 CFU/g after 30 days at 25°C, which made it easier to transport and store. They also demonstrated good stability in artificial digestion fluids, with an NLB of over 1012 CFU/g after sequential treatments, which enabled them to maintain effectiveness in the animal gastrointestinal tract. Finally, the MCPs were fed to the mealworms (Tenebrio molitor) and raccoon dogs (Nyctereutes procyonoides) in order to test their effectiveness, and the growth rates of both significantly improved with the MCPs feeding. This study thus demonstrated that culturing MCPs on a solid-state medium is an efficient method to affordably produce probiotic feed additives that can improve the performance of very physiologically different animals, such as the mealworm and raccoon dog, which indicates their potential for very wide applicability.

Degradable magnesium implant-associated infections by bacterial biofilms induce robust localized and systemic inflammatory reactions in a mouse model

Biomaterial-associated Pseudomonas aeruginosa biofilm infections constitute a cascade of host immune reactions ultimately leading to implant failure. Due to the lack of relevant in vivo biofilm models, the majority of the studies report host immune responses to free-living or planktonic bacteria, while bacteria in clinical situations live more frequently as biofilm communities than as single cells. The present study investigated host immune responses to biomaterial-associated P. aeruginosa biofilms in a clinically relevant mouse model. Previously, we reported metallic magnesium, a prospective biodegradable implant, to be permissive for bacterial biofilm in vivo even though it exhibits antibacterial properties in vitro. Therefore, magnesium was employed as biomaterial to investigate in vivo biofilm formation and associated host immune responses by using two P. aeruginosa strains and two mouse strains. P. aeruginosa formed biofilm on subcutaneously implanted magnesium disks. Non-invasive in vivo imaging indicated transient inflammatory responses at control sites, whereas robust prolonged interferon-β (IFN-β) expression was observed from biofilm in a transgenic animal reporter. Furthermore, immunohistology and electron microscopic results showed that bacterial biofilms were located in 2D immediately on the implant surface and at a short distance in the adjacent tissue. These biofilms were surrounded by inflammatory cells (mainly polymorphonuclear cells) compared to the controls. Interestingly, even though the number of live bacteria in various organs remained below detectable levels, splenomegaly indicated systemic inflammatory processes. Overall, these findings confirmed the resistance of biofilm infections in vivo to potentially antibacterial properties of magnesium degradation products. In vivo imaging and histology indicated the induction of both local and systemic host inflammatory responses to P. aeruginosa biofilms. Even though the innate host immune defenses could not eliminate the local infection for up to two weeks, there was no apparent systemic bacteremia and all the animals investigated survived the infection.

Isıl İşlem Görmüş Sütlerde Salmonella Typhimurium Canlı Hücrelerinin PMA/Real-Time PCR ile Belirlenmesi

Applying different technological processes during the production of food has a lethal effect on the bacteria but DNA of these bacterial strains may cause false positive results when detected by real time PCR technique because they preserve their existence for a certain period of time. To overcome this shortcoming of the real time PCR technique, a new method has been developed in recent years, based on the removal of dead cell DNA from the medium by treatment with Propodium Monoazide (PMA) before DNA extraction. In this study, real-time PCR method was combined with PMA application for the detection of live cells of Salmonella Typhimurium in heat treated milk samples. For this purpose, milk samples inoculated with S. Tyhimurium were heat treated at different temperatures (60, 65, 70 and 75°C) and times (15, 60, 300, 900 sec) and number of live bacteria was determined comparatively by direct real-time PCR, PMA/real-time PCR and conventional cultural method. As a result, unlike the direct real time PCR technique, PMA/real-time PCR method prevents to a certain extent of false positive results from dead cells at all tested temperatures and times but higher results were obtained from PMA/real-time PCR method when compared to conventional cultural results. Therefore, further studies should be carried out to optimize the conditions of the PMA application in order to eliminate the high positive results detected by the PMA / real-time PCR method

Efficient water disinfection with Ag2WO4-doped mesoporous g-C3N4 under visible light

Ag2WO4/g-C3N4 composite photocatalyst was synthesized by polymerization of thiourea and ammonia chloride combined with the deposition-precipitation method, which was applied as an efficient visible-light driven photocatalyst for inactivating Escherichia coli (E. coli). The physicochemical properties of these photocatalysts were systematically characterized by various techniques such as SEM, TEM, XRD, FT-IR, BET, UV–vis DRS and PL. The synthesized photocatalysts exhibited outstandingly enhanced photocatalytic disinfection efficiency compared with that of pure g-C3N4 and Ag2WO4 under visible light. Furthermore, the optimal mass ratio of the Ag2WO4 to g-C3N4 was 5wt%, and a number of live bacteria could be completely inactivated with Ag2WO4(5%)/g-C3N4 (100μg/mL) after 90min under visible light irradiation. The high disinfection efficiency is due to the synergetic effect between g-C3N4 and Ag2WO4, including a good distribution of Ag2WO4 particles on the surface of g-C3N4 and an improved separation rate of photogenerated electron-hole pairs. The enhanced disinfection mechanism was also investigated using photogenerated current densities and electrochemical impedance spectroscopy (EIS). Considering the bulk availability and excellent disinfection activity of Ag2WO4/g-C3N4 composite, it is a promising solar-driven photocatalyst for cleaning the microbial contaminated water.

Study of Crystal Formation and Nitric Oxide (NO) Release Mechanism from S-Nitroso-N-acetylpenicillamine (SNAP)-Doped CarboSil Polymer Composites for Potential Antimicrobial Applications.

Stable and long-term nitric oxide (NO) releasing polymeric materials have many potential biomedical applications. Herein, we report the real-time observation of the crystallization process of the NO donor, S-nitroso-N-acetylpenicillamine (SNAP), within a thermoplastic silicone-polycarbonate-urethane biomedical polymer, CarboSil 20 80A. It is demonstrated that the NO release rate from this composite material is directly correlated with the surface area that the CarboSil polymer film is exposed to when in contact with aqueous solution. The decomposition of SNAP in solution (e.g. PBS, ethanol, THF, etc.) is a pseudo-first-order reaction proportional to the SNAP concentration. Further, catheters fabricated with this novel NO releasing composite material are shown to exhibit significant effects on preventing biofilm formation on catheter surface by Pseudomonas aeruginosa and Proteus mirabilis grown in CDC bioreactor over 14 days, with a 2 and 3 log-unit reduction in number of live bacteria on their surfaces, respectively. Therefore, the SNAP-CarboSil composite is a promising new material to develop antimicrobial catheters, as well as other biomedical devices.

Characterization of the protective immune response to Yersinia pseudotuberculosis infection in mice vaccinated with an LcrV-secreting strain of Lactococcus lactis

BackgroundPseudotuberculosis is an infection caused by the bacterial enteropathogen Yersinia pseudotuberculosis and is considered to be a significant problem in veterinary medicine. We previously found that intranasal administration of a recombinant Lactococcus lactis strain that secretes the low-calcium response V (LcrV) antigen from Y. pseudotuberculosis (Ll-LcrV) confers protection against a lethal Y. pseudotuberculosis infection. Here, we aimed at characterizing the immunological basis of this LcrV-elicited protective response and at determining the duration of vaccine-induced immunity. MethodsSplenocytes from BALB/c mice intranasally immunized with Ll-LcrV or Ll as control were immunostained then analyzed by flow cytometry. Protection against a lethal intravenous injection of Y. pseudotuberculosis was also determined (i) in immunized BALB/c mice depleted or not of CD4+, CD8+ or CD25+ cells and (ii) in naïve BALB/c mice receiving serum from immunized mice by counting the number of bacteria in liver and spleen. Lastly, survival rate of immunized BALB/c mice following a lethal intravenous injection of Y. pseudotuberculosis was followed up to 9-months. ResultsWe found that T and B lymphocytes but not non-conventional lymphoid cells were affected by Ll-LcrV immunization. We also observed that depletion of CD4+ and CD25+ but not CD8+ cells in immunized mice eradicated protection against a lethal systemic Y. pseudotuberculosis infection, suggesting that activated CD4+ T lymphocytes are required for vaccine-induced protection. Adoptive transfer of LcrV-specific antibodies from Ll-LcrV-immunized animals significantly reduced the bacterial counts in the liver compared to non-vaccinated mice. Lastly, the protective immunity conferred by Ll-LcrV decreased slightly over time; nevertheless almost 60% of the mice survived a lethal bacterial challenge at 9months post-vaccination. ConclusionMucosal vaccination of mice with Ll-LcrV induced cell- and antibody-mediated protective immunity against Y. pseudotuberculosis infection in the mouse and the protection is long-lasting.

Mice deficient in IL-12p35 or IL-12p40 develop renal lesions during Chlamydia muridarum urogenital infection

Objective To study the roles of IL-12 and IL-23 in the development of protective immunity and pathological changes during chlamydial urogenital infection. Methods C57BL/6J wild type (wt) mice and mice deficient in IL-12p35 (IL-12p35 KO) or IL-12p40 (IL-12p40 KO)were inoculated intravaginally with 1×104 IFU of live Chlamydia muridarum (C. muridarum) organisms. Half mice of each group were reinfected on day 114 after primary infection. Vaginal swabs were taken every 3 or 4 days to monitor live organism shedding. The mice were sacrificed after 114 or 143 days of primary infection and the vaginal tract and kidney samples were collected for pathological analysis. The numbers of chlamydial inclusion bodies and bacteria in kidney homogenates were titrated after 100 days of primary infection. Results The infection time courses of mice deficient in either IL-12p35 or IL-12p40 were similar after primary infection, but were prolonged as compared with the wild type mice. All mice regardless of genotypes developed severe pathological damages in upper genital tracts with no significant difference among different groups. Almost all IL-12p40 KO mice and some IL-12p35 KO mice showed pathological changes in kidney samples. No obvious abnormality was observed in any of the kidneys from wild type mice. Neither the age-matched IL-12p35 KO nor IL-12p40 KO mice developed any gross pathological changes in kidney in the absence of chlamydial infection. C. muridarum inclusions were detected in kidney samples with gross pathological damages from IL-12p35 KO mice and IL-12p40 KO mice. No inclusions were ever detected in kidneys from the wild type mice. The numbers of chlamydial inclusions in the IL-12p40 KO mice were much higher than those of the IL-12p35 KO mice. Live bacteria were detected in mice deficient in either IL-12p35 or IL-12p40, but not in the wild type mice. No significant difference with the number of live bacteria was found between IL-12p35 KO mice and IL-12p40 KO mice. Conclusion IL-12 and IL-23 could inhibit the spread of C. muridarum infection from genital tract to kidney. The deficiency of IL-12 or IL-23 might relate to the renal lesions induced by Chlamydia infection. Key words: Chlamydia muridarum (MoPn); IL-12p35; IL-12p40; Urogenital tract infection; Renal lesion

Antibacterial properties of Acinetobacter baumannii phage Abp1 endolysin (PlyAB1).

BackgroundAcinetobacter baumannii has emerged as one of the most important hospital-acquired pathogens in the world, because of its resistance to almost all available antibiotic drugs. Endolysins from phages are attracting increasing interest as potential antimicrobial agents, especially for drug-resistant bacteria. We previously isolated and characterized Abp1, a virulent phage targeting the multidrug-resistant A. baumannii strain, AB1.MethodsTo evaluate the antimicrobial potential of endolysin from the Abp1 phage, the endolysin gene plyAB1 was cloned and over-expressed in Escherichia coli, and the lytic activity of the recombinant protein (PlyAB1) was tested by turbidity assessment and bacteria counting assays.ResultsPlyAB1 exhibits a marked lytic activity against A. baumannii AB1, as shown by a decrease in the number of live bacteria following treatment with the enzyme. Moreover, PlyAB1 displayed a highly specific lytic effect against all of the 48 hospital-derived pandrug-resistant A. baumannii isolates that were tested. These isolates were shown to belong to different ST clones by multilocus sequence typing.ConclusionsThe results presented here show that PlyAB1 has potential as an antibiotic against drug-resistant A. baumannii.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0681-2) contains supplementary material, which is available to authorized users.

550a Loss of PTPN22 Regulates MDP Induced Signaling, Cytokine Release, Autophagy and Inflammasome Activation

effect of early exposure on neonatal development is unknown. Here we focused on early exposure to PM since children and young adults are most commonly affected with IBD. Our aim was to study the effect of airborne PM on developing intestine in the IL-10-/colitis model, and if chronic exposure during the neonatal period would alter disease development and/or have long-lasting effects that would alter gut responses to injury in later life. Methods: IL-10-/pregnant dams and pups were fed mouse chow with/without PM (9μg/g) and pups were studied at 10 and 14 weeks of age. At 20 weeks of age, mice were subjected to 2% DSS in drinking water for 5 days followed by 2 days recovery. Homogenates from mesenteric lymph nodes (MLN) were cultured to measure bacterial translocation. To examine mucosal immune function, segments of small and large intestines were homogenized for cytokine analysis via MesoScale discovery platform. Results: PM exposure had no effect on mouse weight gain but did increase colonic pro-inflammatory cytokine expression at 10 and 14 weeks of age (Table). However, IL-17 levels were reduced in PM-fed mice at 10 weeks but did increase by 14 weeks when compared to age-matched controls. In addition, increased levels of bacterial translocation into MLN were seen at 10 weeks. By 20 weeks, PM-fed mice showed changes in the small intestine with decreased IL-1 β but increased TNFα and IFNγ, suggesting changes in both innate and adaptive immunity. PM-fed mice responded to DSS treatment with increased colonic TNFα and IL-1β compared with non-PM fed mice. In addition, there were increased numbers of live bacteria in the MLN of DSS treated PM-fed mice compared to DSS treated control chow-fed mice. Conclusions: IL-10-/neonatal mice exposed to PM had an increased bacterial translocation and earlier onset of inflammatory disease. Continual exposure into adulthood resulted in small intestinal inflammation and a reduction in bacterial killing capacity in the MLN. Our data suggests that early exposure to air pollution particulates can result in an earlier onset of intestinal disease in geneticallysusceptible hosts and can alter responses to gut injury in later life. Cytokine Expression Levels in the Colon

Effects of Wood Amendments on the Degradation of Terbuthylazine and on Soil Microbial Community Activity in a Clay Loam Soil

The herbicide terbuthylazine is widely used within the EU; however, its frequent detection in surface and groundwater, together with its intrinsic toxicological properties, may pose a risk both for human and environmental health. Organic amendments have recently been proposed as a possible herbicide sorbent in soil, in order to limit herbicide movement from soil to water. The environmental fate of terbuthylazine depends not only in its mobility but also in its persistence. The latter is directly dependent on microbial degradation. For this reason, the effects of pine and oak residues on terbuthylazine soil microbial community functioning and on the potential of this community for terbuthylazine degradation were studied. For this purpose, degradation kinetics, soil dehydrogenase activity and the number of live bacteria were assessed in a clay loam soil treated with terbuthylazine and either amended with pine or oak wood or unamended (sterilised and non-sterilised). At day 65, 85 % of the herbicide applied still persisted in the sterile soil, 73 % in the pine-amended one and 63 % in the oak-amended and unamended ones. Pine residues increased the sorption of terbuthylazine to soil and hampered microbial degradation owing to its high terbuthylazine sorption capacity and a decrease in the bioavailability of the herbicide. On the contrary, in the presence of oak residues, the herbicide sorption did not increase significantly. The overall results confirm the active role of the soil microbial community in terbuthylazine degradation in amended and unamended soils and in a liquid enrichment culture performed using an aliquot of the same soil as the inoculum. In this clay loam soil, in the absence of amendments, the herbicide was found to be quite persistent (t 1/2 > 95 days), while in the enrichment culture, the same natural soil bacterial community was able to halve terbuthylazine in 24 days. The high terbuthylazine persistence in this soil was presumably ascribable to its texture and in particular to the mineralogy of the clay fraction.

Comparative Efficacy of Commercially Available and Emerging Antimicrobial Urinary Catheters Against Bacteriuria Caused by E. coli In Vitro

To compare the efficacy of both commercially available and emerging urinary catheter technologies in relation to their effects on bacteriuria caused by Escherichia coli in vitro. Antiseptic urinary catheters have recently become commercially available and others are in the developmental stage. Silver alloy-coated catheters, antibiotic Nitrofurazone (NF)-coated catheters, and nitric oxide (NO)-coated catheters were tested against a noncoated control for their antiseptic ability. Inhibition of bacterial growth, biofilm formation, and the number of live bacteria within the biofilm, using up to 10(3) bacterial load were evaluated. Experiments were performed either in E. coli containing Luria broth media or in urine infected with E. coli. NF- and NO-coated catheters had equivalent antimicrobial activity and eradicated all bacteria in planktonic and biofilm states. Silver-coated catheters had no effect on E. coli growth or biofilm formation compared with the control, although silver-coated catheters did inhibit bacterial levels within the biofilm by 50%. NF- and NO-coated catheters are highly effective in preventing planktonic growth and biofilm formation. Silver-coated catheters were not found to be effective in this study.

Rapid antibiotic efficacy screening with aluminum oxide nanoporous membrane filter-chip and optical detection system

We have developed a filter-chip and optical detection system for rapid antibiotic efficacy screening. The filter-chip consisted of a 1-mL reservoir and an anodic aluminum oxide (AAO) nanoporous membrane. Sample solution with liquid growth media, bacteria, and antibiotics was incubated in the reservoir for a specific period of time. The number of live bacteria on the surface of membrane was counted after the incubation with antibiotics and filtration. Using this biosensing system, we have demonstrated a 1-h antibiotic screening for patients’ clinical samples, significantly faster than the conventional antibiotic susceptibility tests that typically take more than 24 h. This rapid screening nature makes the filter-chip and detection system ideal for tailoring antibiotic treatment to individual patients by reducing the microbial antibiotic resistance, and improving the survival rate for patients suffering from postoperative infections.

Pulmonary Collectins Protect Macrophages against Pore-forming Activity of Legionella pneumophila and Suppress Its Intracellular Growth

Pulmonary collectins, surfactant proteins A (SP-A) and D (SP-D), play important roles in innate immunity of the lung. Legionella pneumophila is a bacterial respiratory pathogen that can replicate within macrophages and causes opportunistic infections. L. pneumophila possesses cytolytic activity, resulting from insertion of pores in the macrophage membrane upon contact. We examined whether pulmonary collectins play protective roles against L. pneumophila infection. SP-A and SP-D bound to L. pneumophila and its lipopolysaccharide (LPS) and inhibited the bacterial growth in a Ca(2+)-dependent manner. The addition of LPS in the culture blocked the inhibitory effects on L. pneumophila growth by the collectins, indicating the importance of LPS-collectin interaction. When differentiated THP-1 cells were infected with L. pneumophila in the presence of SP-A and SP-D, the number of permeable cells was significantly decreased, indicating that pulmonary collectins inhibit pore-forming activity of L. pneumophila. The number of live bacteria within the macrophages on days 1-4 after infection was significantly decreased when infection was performed in the presence of pulmonary collectins. The phagocytosis experiments with the pH-sensitive dye-labeled bacteria revealed that pulmonary collectins promoted bacterial localization to an acidic compartment. In addition, SP-A and SP-D significantly increased the number of L. pneumophila co-localized with LAMP-1. These results indicate that pulmonary collectins protect macrophages against contact-dependent cytolytic activity of L. pneumophila and suppress intracellular growth of the phagocytosed bacteria. The promotion of lysosomal fusion with Legionella-containing phagosomes constitutes a likely mechanism of L. pneumophila growth suppression by the collectins.

Effects of low concentrations of the phenylurea herbicide diuron on biofilm algae and bacteria

A system of recirculating channels was used in this study to examine the long-term effects (29 d) of environmentally realistic concentrations of the herbicide diuron (from 0.07 to 7 μg L −1) on biofilm communities. The autotrophic activity of biofilms was affected by this herbicide, as reflected by a marked decrease in the photosynthetic efficiency. Diuron exposure also increased chlorophyll- a content and reduced the biovolume of diatom taxa at low concentrations. The effects on bacteria were also remarkable. Bacterial abundance was reduced after a week of exposure to the herbicide at a range of concentrations. Effects were on the number of live bacteria and on the increase in the leucine-aminopeptidase activity. It is suggested that inputs of herbicides to the river ecosystem at low concentrations may cause a chain of effects in the biofilm, which include inhibitory effects on algae but also indirect effects on the relationships between biofilm components.

명조건에서 발아시킨 콩을 이용한 청국장의 발효 특성

This study was conducted to investigate the fermentation characteristics of cheonggukjang prepared with soybean germinated under light condition. The moisture content and pH of cheonggukjang made with soybean germinated under light condition (CGL) were higher than that of cheonggukjang made with non-germinated soybean (CNG). The color of CGL was darker than that of CNG and cheonggukjang made with soybean germinated under dark condition (CGD). The number of live bacteria in the CGL () and CGD () was higher than that of CNG (). The levels of isoflavone in CGL, CGD and CNG were 2,038.0, 1,993.6 and 1,747.0 ug/g, respectively. There were no significant differences in the appearance, aroma, taste and overall acceptability of the cheonggukjang made with different germination conditions. Therefore, it was expected that the cheonggukjang prepared with soybean germinated under light condition could be practically used as a new fermented food.

Changes in the microbial activity in a soil amended with oak and pine residues and treated with linuron herbicide

This work studies the effects of wood amendments on soil microbial community functioning and on the potential of this community for linuron degradation. For this purpose, soil dehydrogenase activity and the number of live bacteria, which represent broad scale measurements of the activity and viability of soil organisms, were assessed in soil treated with linuron and either amended with pine or oak wood or unamended (sterilized and non-sterilized). The overall results show that the microbial community had a significant role in linuron degradation. The linuron half-life values indicated a slower degradation rate in pine and oak amended soils than in unamended ones. This is attributed both to the higher sorption of linuron by these soils compared to the unamended ones and a consequent lower bioavailability of the herbicide for microbial degradation, and to the use of the pine and oak as an alternative carbon source by degrading microorganisms. Linuron did not affect the microbial community in terms of dehydrogenase activity and number of live bacteria, presumably because it had adapted to the herbicide. However, the dehydrogenase activity was significantly higher in the soils amended with pine or oak than in the non-amended ones, indicating that the presence of a carbon source favoured the overall bacterial community.

Study for evidence of bacteria contamination in the southern part of the Diyala River / Iraq

Were studied some bacteria evidence of pollution as well as the total number of live bacteria in the waters of the Diyala river and selected five stations within the 17 km final Diyala River before its mouth in the Tigris River was the first before the new bridge of the Diyala River about 4 km and the second after the mouth of the water purification plant Rustumiya suit inverselywith temperatures

Aquaporin-4 Gene Disruption in Mice Reduces Brain Swelling and Mortality in Pneumococcal Meningitis

The astroglial water channel aquaporin-4 (AQP4) facilitates water movement into and out of brain parenchyma. To investigate the role of AQP4 in meningitis-induced brain edema, Streptococcus pneumoniae was injected into cerebrospinal fluid (CSF) in wild type and AQP4 null mice. AQP4-deficient mice had remarkably lower intracranial pressure (9 +/- 1 versus 25 +/- 5 cm H2O) and brain water accumulation (2 +/- 1 versus 9 +/- 1 microl) at 30 h, and improved survival (80 versus 0% survival) at 60 h, through comparable CSF bacterial and white cell counts. Meningitis produced marked astrocyte foot process swelling in wild type but not AQP4 null mice, and slowed diffusion of an inert macromolecule in brain extracellular space. AQP4 protein was strongly up-regulated in meningitis, resulting in a approximately 5-fold higher water permeability (P(f)) across the blood-brain barrier compared with non-infected wild type mice. Mathematical modeling using measured P(f) and CSF dynamics accurately simulated the elevated lower intracranial pressure and brain water produced by meningitis and predicted a beneficial effect of prevention of AQP4 upregulation. Our findings provide a novel molecular mechanism for the pathogenesis of brain edema in acute bacterial meningitis, and suggest that inhibition of AQP4 function or up-regulation may dramatically improve clinical outcome.

Antibody-Dependent Killing of Meningococci by Human Neutrophils in Serum of Late Complement Component-Deficient Patients

Background: Thirty-one Russian patients with late complement component deficiency (LCCD) who had experienced one to five meningococcal infections were immunized with meningococcal polysaccharide vaccine (A + C + W135 + Y) and were followed for 3–8 years. We investigated the potentially protective killing effect of human neutrophils (PMNL) on serogroup A and W135 meningococci. Methods: Meningococci were incubated in LCCD vaccinee sera in the absence or presence of PMNL, and the number of live bacteria (CFU) was determined by plating onto chocolate agar. Results: When meningococci were incubated in the LCCD sera alone, exponential growth of meningococci occurred despite the presence of meningococcal antibodies. After the addition of PMNL, meningococci were inhibited in their growth or even eliminated. Group A or W135 meningococci were killed effectively by PMNL in 80% of the sera which were collected 1 month to 1 year after vaccination compared to only 40% in the prevaccination LCCD sera (p < 0.05). Three years after vaccination 67% of the LCCD sera were still capable of promoting killing (and even 90% after revaccination). The rate of killing correlated with the concentration of serogroup-specific immunoglobulins. In 83% of the 72 LCCD sera with more than 5 µg/ml anti-group A immunoglobulins the killing of group A meningococci was promoted. By contrast, only 21% of 19 samples with lower specific antibody levels showed a PMNL-mediated meningococcal killing (p < 0.05). The same effect was observed for group W135 meningococci. Conclusion: PMNL kill meningococci during incubation in LCCD serum; this effect increases after vaccination and depends on both specific antibody and complement. Protection by vaccination may therefore be caused by an increased killing capacity of PMNL.

Activity of moxifloxacin by itself and in combination with ethambutol, rifabutin, and azithromycin in vitro and in vivo against Mycobacterium avium.

Moxifloxacin activity against Mycobacterium avium complex (MAC) was evaluated in vitro against 25 strains. The MIC was determined to range from 0.125 to 2.0 microg/ml. In addition, U937 macrophage monolayers infected with MAC strain 101 (serovar 1) were treated with moxifloxacin (0.25 to 8 microg/ml) daily, and the number of intracellular bacteria was quantitated after 4 days. Moxifloxacin showed inhibitory activity at 0.5 microg/ml and higher. To assess the activity of moxifloxacin containing regimens in vivo, we infected C57BL bg(+)/bg(+) mice with 3 x 10(7) MAC strain 101 bacteria intravenously. One week later treatment was begun with the following: (i) moxifloxacin (50 mg/kg/day or 100 mg/kg/day), ethambutol (100 mg/kg/day), or a combination of moxifloxacin and ethambutol; or (ii) moxifloxacin (100 mg/kg/day), azithromycin (200 mg/kg/day), or rifabutin (40 mg/kg/day) as oral monotherapy; or (iii) all permutations of two-drug therapy or all three drugs in combination. All groups contained at least 14 animals, and the control group received the drug vehicle. After 4 weeks, quantitative blood cultures were obtained and the number of bacteria in liver and spleen was quantitated. Moxifloxacin, ethambutol, and azithromycin were active as single agents in liver, spleen, and blood. Rifabutin showed inhibitory activity only in the blood. Two-drug combinations containing azithromycin were no more active than azithromycin alone. Similarly, the three-drug combination was not more active than azithromycin alone in the spleen. Rifabutin did not add to the activity of any other single agent or two-drug combination. Moxifloxacin at both concentrations in combination with ethambutol was significantly more active than each drug alone.