Sensitive Bacteria Research Articles

Dead or Alive: Deoxyribonuclease I Sensitive Bacteria and Implications for the Sinus Microbiome

Recently, there has been tremendous interest in the sinus microbiome and how it relates to disease. However, a lack of a standardized sample collection and DNA extraction methods makes comparison of results across studies nearly impossible. Furthermore, current techniques fail to identify which components of the microbiome are actually alive within the host at the time of sampling. To develop and optimize a method to differentiate which bacterial species in the human sinus microbiome are live versus dead. Duplicate samples from the middle meatus of patients with healthy sinus tissue and those patients with chronic rhinosinusitis were collected by using brushes (n = 12), swabs (n = 27), and tissue biopsy (n = 8) methods. One sample from each pair was either deoxyribonuclease I- or control-treated before DNA extraction. The relative bacterial versus human composition of each sample was determined. A 16S ribosomal RNA gene analysis was performed on a six-paired sample from patients with healthy sinus tissue. We found that swabs and brushes collected a higher percentage of bacterial DNA than did tissue biopsy. We also determined that as much as 50% of the bacteria collected in these samples was already dead at the time of collection. The 16S ribosomal RNA gene analysis found significant changes in the relative abundance of taxa identified in the live versus dead bacterial communities of healthy human sinuses. Our findings indicated that swabs provided the best quality microbiome samples and that a large portion of the bacteria identified in the sinus were deoxyribonuclease I sensitive. These results highlighted the need for improved techniques such as those presented here, which can differentiate between living and dead bacteria in a sample, a potentially critical distinction when examining changes in sinus innate immune function because both components play important, but distinct, functions. Further studies will determine how these living and dead bacterial populations shift in different disease states and after clinical intervention.

CORR Insights(®): Biofilm Antimicrobial Susceptibility Increases With Antimicrobial Exposure Time.

Where Are We Now? Biofilm formation by pathogenic bacteria is a recognized virulence factor important in the persistence of chronic infections. When growing as biofilms, even antibiotic sensitive bacteria (as measured by the planktonic broth minimum inhibitory concentration [MIC] and minimum bactericidal concentration [MBC] methods) become highly tolerant of antibiotics. In part, this tolerance is due to the presence of a small fraction (< 1 %) of slow-growing “persister” cells and small colony variants which, according to some, cannot be killed by antibiotics alone, regardless of concentration [1, 5]. However, this would contradict other studies which report achieve complete sterilization of biofilms as the basis for the Minimum Biofilm Eradication Concentration (MBEC) assay [2]. The MBEC is based on a 24-hour antibiotic exposure period in accordance with the classic MIC and MBC. However, in device related infections, such as orthopaedic periprosthetic infection, high concentrations of antibiotics may be delivered locally from antibiotic loaded depots (bone cement) during periods of weeks or months. Recent work by Howlin et al. [4] has demonstrated that multiple days of exposure to high concentrations of antibiotics were required to achieve significant reductions or complete killing of biofilms. While a 24-hour MIC or MBC is convenient and may be useful for determining dosages to kill rapidly growing planktonic cultures, it may not be particularly useful for slow growing biofilms. Even the 24-hour MBEC, which is specifically designed to provide guidance in treating bacteria grown in the biofilm phenotype, might reflect the influence of exposure time on an appropriate scale relevant to biofilms. The study by Castaneda and colleagues measures the MBEC of five common biofilm forming pathogens as a function of exposure time to vancomycin and tobramycin alone and in combination. In the United States, these two antibiotics are commonly incorporated into bone cements by surgeons to treat orthopaedic infections. The MBEC was measured at one, three, and five days. The authors found the MBEC of 11 of 14 pathogen antibiotic combinations was lower than the 24-hour assay after Day 3. They also found that on Day 5, 13 of 14 pathogen antibiotic combinations were lower, with the exception attributed to contamination by between a two and eight-fold difference depending on the pathogen and the antibiotic. The authors concluded that a 24-hour assay might actually overestimate the concentration of antibiotic that needs to be administered in order to eradicate a biofilm infection if the exposure time is not taken into consideration. However, this highlights an area of tension that clinicians face, between the need to act quickly in order to suppress or kill a biofilm infection versus the more complex and lengthy culturing methods to determine susceptibility. Further, the MBEC itself, although a useful research tool, is not yet accepted as a “gold standard,” and there is little, if any, indication on how MBEC guided therapeutics may correlate with clinical efficacy. Where Do We Need To Go? The study by Castaneda and colleagues exemplifies many of the biofilm specific issues that need to be addressed in order to provide better guidance to physicians and surgeons on the appropriate application of antibiotics to treat biofilm infections. Despite the fact that biofilms have been widely recognized as critical in many chronic infections for at least a decade, progress on two of the most important issues remains stubbornly mired—diagnostics and treatment. A main reason is the lack of standard methods for growing and testing biofilms. Working with planktonic cultures is convenient since the bacteria can be grown to ensure a homogeneous distribution both physically and by growth phase. They can be readily diluted to achieve standard concentrations. Biofilms are not so domesticated, their surface density is difficult to control and since they are on a surface they cannot be readily divided into defined inoculum. Further, biofilms harbor many different phenotypes including slow growing small colony variants or dormant persisters and will be influenced by the type of surface and age. How Do We Get There? Since biofilm formation is a developmental process the susceptibility will vary with maturity. One of the biggest contributions in advancing biofilm medicine is to develop relevant and robust standard culture and susceptibility methods. Darla M. Goeres PhD and the team at the Center for Biofilm Engineering is pioneering the development of such methods for disinfection and sanitization [3] with the ASTM International, the US Environmental Protection Agency, and Centers for Disease Control & Prevention, including ASTM E2799 for the MBEC method [6]. Encouragingly, they are also working with the FDA. Meaningful advancement will only be made when: (1) Regulatory agencies and bodies such as the Clinical and Laboratory Standards Institute fully recognize the urgent need for it, and (2) government and industry funding is adequate to enable the development of such methods for medical application.

An Alteration of Lymphocytes Subpopulations and Immunoglobulins Levels in Patients with Diabetic Foot Ulcers Infected Particularly by Resistant Pathogens.

The aim of our study was to analyse immune abnormalities in patients with chronic infected diabetic foot ulcers (DFUs) especially those infected by resistant microorganisms. Methods. 68 patients treated in our foot clinic for infected chronic DFUs with 34 matched diabetic controls were studied. Patients with infected DFUs were subdivided into two subgroups according to the antibiotic sensitivity of causal pathogen: subgroup S infected by sensitive (n = 50) and subgroup R by resistant pathogens (n = 18). Selected immunological markers were compared between the study groups and subgroups. Results. Patients with infected chronic DFUs had, in comparison with diabetic controls, significantly reduced percentages (p < 0.01) and total numbers of lymphocytes (p < 0.001) involving B lymphocytes (p < 0.01), CD4+ (p < 0.01), and CD8+ T cells (p < 0.01) and their naive and memory effector cells. Higher levels of IgG (p < 0.05) including IgG1 (p < 0.001) and IgG3 (p < 0.05) were found in patients with DFUs compared to diabetic controls. Serum levels of immunoglobulin subclasses IgG2 and IgG3 correlated negatively with metabolic control (p < 0.05). A trend towards an increased frequency of IgG2 deficiency was found in patients with DFUs compared to diabetic controls (22% versus 15%; NS). Subgroup R revealed lower levels of immunoglobulins, especially of IgG4 (p < 0.01) in contrast to patients infected by sensitive bacteria. The innate immunity did not differ significantly between the study groups. Conclusion. Our study showed changes mainly in the adaptive immune system represented by low levels of lymphocyte subpopulations and their memory effector cells, and also changes in humoral immunity in patients with DFUs, even those infected by resistant pathogens, in comparison with diabetic controls.

Effect of Nanohexaconazole on Nitrogen Fixing Blue Green Algae and Bacteria.

Nanohexaconazole is a highly efficient fungicide against Rhizoctonia solani. Nanoparticles are alleged to adversely affect the non-target organisms. In order to evaluate such concern, the present study was carried out to investigate the effect of nanohexaconazole and its commercial formulation on sensitive nitrogen fixing blue green algae (BGA) and bacteria. Various activities of algae and bacteria namely growth, N-fixation, N-assimilation, Indole acetic acid (IAA) production and phosphate solubilization were differently affected in the presence of hexaconazole. Although, there was stimulatory to slightly inhibitory effect on the growth measurable parameters of the organisms studied at the recommended dose of nanohexaconazole, but its higher dose was inhibitory to all these microorganisms. On the other hand, the recommended as well as higher dose of commercial hexaconazole showed much severe inhibition of growth and metabolic activity of these organisms as compared to the nano preparation. The uses of nanohexazconazole instead of hexaconazole as a fungicide will not only help to control various fungal pathogens but also sustain the growth and activity of these beneficial microorganisms for sustaining soil fertility and productivity.

Multi-scale magnetic nanoparticle based optomagnetic bioassay for sensitive DNA and bacteria detection

An optomagnetic bioassay is optimized by means of extending the linear range in the presence of larger nanoparticles.

Mycothiol protects Corynebacterium glutamicum against acid stress via maintaining intracellular pH homeostasis, scavenging ROS, and S-mycothiolating MetE.

Mycothiol (MSH) plays a major role in protecting cells against oxidative stress and detoxification from a broad range of exogenous toxic agents. In the present study, we reveal that intracellular MSH contributes significantly to the adaptation to acidic conditions in the model organism Corynebacterium glutamicum. We present evidence that MSH confers C. glutamicum with the ability to adapt to acidic conditions by maintaining pHi homeostasis, scavenging reactive oxygen species (ROS), and protecting methionine synthesis by the S-mycothiolation modification of methionine synthase (MetE). The role of MSH in acid adaptation was further confirmed by improving the acid tolerance of C. glutamicum by overexpressing the key MSH synthesis gene mshA. Hence, our work provides insights into a previously unknown, but important, aspect of the C. glutamicum cellular response to acid stress. The results reported here may help to understand acid tolerance mechanisms in acid sensitive bacteria and may open a new avenue for improving acid resistance in industry strains for the production of bio-based chemicals from renewable biomass.

Comparison of microbiological profile of pathogens isolated from early-onset and late-onset ventilator-associated pneumonia in a tertiary care center

Background and Objectives: Ventilator- Associated Pneumonia (VAP), an important form of Hospital Acquired Pneumonia, specifically refers to pneumonia developing in a patient on Mechanical Ventilator for more than 48 hours after intubation or tracheostomy. The time of onset of pneumonia is an important risk factor for specific pathogens & outcome in patients with VAP. Early onset VAP (EO- VAP), defined as occurring within first 4 days of hospitalization, usually caused by antibiotic sensitive bacteria i.e., community acquired, whereas the late onset (LO-VAP) i.e., more than 5 days are associated with increased mortality in patient. The emergence of Multi-Drug Resistant (MDR) pathogens is becoming a therapeutic challenge as the treatment alternatives are unavailable, toxic and with poor outcome. VAP requires a rapid diagnosis and initiation of appropriate antibiotic treatment, to prevent mortality and morbidity. Early detection of pathogens causing VAP helps to control their spread by administration of suitable antibiotics and proper infection control measures. The study was conducted to compare the bacteriological profile of pathogens causing EO-VAP and LO VAP in Fr. Muller Medical College Hospital. Materials and Methods: A total of 100 patients, on mechanical ventilation for more than 48 hours who were diagnosed to have VAP were included in the study between May 2009 to April 2010. Their Endotracheal Aspirate were collected and processed. From 100 pathogens of count >10 5 CFU/mL were characterized and antibiogram was determined using standard antibiotics regime. Results: Among 100 patients studied, fifty five patients were of LO-VAP and remaining forty five were EO-VAP. Acinetobacter species, Klebsiella pneumoniae, Pseudomonas aeruginosa were the most common pathogens causing VAP. Majority of the pathogens causing EO- and LO-VAP had similar sensitivity pattern, i.e., sensitive to high end antibacterials like Levofloxacin, Amikacin, Carbapenemes. Conclusion: In the patients studied, there was no difference in the antibiogram of the pathogens causing EO- and LO-VAP.

Host population bottlenecks drive parasite extinction during antagonistic coevolution.

Host–parasite interactions are often characterized by large fluctuations in host population size, and we investigated how such host bottlenecks affected coevolution between a bacterium and a virus. Previous theory suggests that host bottlenecks should provide parasites with an evolutionary advantage, but instead we found that phages were rapidly driven to extinction when coevolving with hosts exposed to large genetic bottlenecks. This was caused by the stochastic loss of sensitive bacteria, which are required for phage persistence and infectivity evolution. Our findings emphasize the importance of feedbacks between ecological and coevolutionary dynamics, and how this feedback can qualitatively alter coevolutionary dynamics.

Microbiological quality and inhibitory potential of selected Croatian apiary honeys

The quality of honey is mainly determined by its sensorial, chemical, physical and microbiological properties. The purpose of this research was to evaluate microbiological properties of 72 honey samples and to determine the number and/or presence of aerobic mesophilic and spore-forming bacteria, moulds, yeasts, sulphite-reducing clostridia, bacteria from the Enterobacteriaceae family and Staphylococcus aureus. Microbiological quality of tested samples was considered good and pathogenic bacteria were not present. Inhibitory potential of selected honey samples was also investigated. Among tested honey concentrations (0.1%, 5%, 10%, 25%, 50% and 75%), the final concentration of 75% had the highest potential. Honeydew and chestnut honey exhibited the strongest inhibitory effect against tested bacterial species, while the lowest inhibition was exhibited by linden (lime tree) honey. Comparing the samples of the same honey type, considerably different inhibitory activity can be detected. Overall, the most sensitive bacterium to the inhibitory effect of tested honey samples was Staphylococcus aureus, while the most resistant one was Enterococcus faecalis.

Synthesis, antibacterial, cytotoxicity and sensing properties of starch-capped silver nanoparticles

In this study, we report the antibacterial, cytotoxicity and sensing properties of dextrose reduced starch-capped silver nanoparticles (Ag-NPs) synthesized via a completely green method. The synthesis involved the use of water, starch, and dextrose as the solvent, the stabilizing and the reducing agents respectively. Silver nitrate was used as the silver precursor without the use of any accelerator. The as-synthesised Ag-NPs were characterized with UV–vis absorption spectroscopy, Fourier transform infra-red spectroscopy (FTIR), Raman spectroscopy, X-Ray diffraction analysis (XRD) and high resolution transmission electron microscopy (HR-TEM). All the as-synthesised Ag-NPs showed good antibacterial activities against Escherichia coli and two strains of Pseudomonas aeruginosa, which are antibiotic sensitive and resistant bacteria. The study also indicated that the time of reaction did not have any significant effect on the antibacterial activity of the Ag-NPs synthesized despite the different particle sizes of the as-synthesised Ag-NPs. The cytotoxicity evaluation on human THP-1 monocyte cell line indicated that the as-synthesised Ag-NPs are less toxic than AgNO3 at lower concentrations (2μg/ml). Furthermore, the as-synthesised Ag-NPs were found to be very useful for colorimetric detection of hydrogen peroxide (H2O2) at lower concentration up to 10−10M with a linear regression coefficient value of 0.8822.

Two-peptide bacteriocin PlnEF causes cell membrane damage to Lactobacillus plantarum

Biologically active, artificially synthesized two-peptide bacteriocin PlnEF was used to study its mode of action on sensitive bacteria Lactobacillus plantarum pl2. The data obtained showed that PlnEF induced membrane permeabilization, allowing for the efflux of electrolytes, which was evidenced by the increased extracellular conductivity, the dissipation of transmembrane electrical potential and pH gradient, and rapid intracellular ATP depletion after L. plantarum pl2 cells were treated with PlnEF for minutes. Laser confocal microscopy showed that PlnEF accumulated very quickly in L. plantarum pl2 cells and the accumulation of PlnEF caused damage to cell membrane. Scanning electron microscopy and transmission electron microscopy further showed that PlnEF induced morphological changes and structure disruption to L. plantarum pl2 cells, such as the formation of blebs, microspheres, membrane deformation and cell lysis. In summary, the data obtained show that PlnEF caused cell membrane damage to L. plantarum pl2 cells. Our study reveals the antimicrobial mechanism of two-peptide bacteriocin PlnEF against L. plantarum.

Prospects of a new antistaphylococcal drug batumin revealed by molecular docking and analysis of the complete genome sequence of the batumin-producer Pseudomonas batumici UCM B-321

Meticillin-resistant Staphylococcus aureus (MRSA) is a serious public health threat causing outbreaks of clinical infection around the world. Mupirocin is a promising anti-MRSA drug, however mupirocin-resistant strains of S. aureus are emerging at an increasing rate. The newly discovered antibiotic batumin may contribute to anti-MRSA therapy. The objective of this work was to identify possible molecular targets for batumin as well as mechanisms of its antistaphylococcal activity using computational molecular docking and by analysing the complete genome sequence of the batumin-producer Pseudomonas batumici UCM B-321. It was found that batumin acted very similarly to mupirocin by inhibiting aminoacyl tRNA synthetases. A previous hypothesis considering the trans-enoyl-CoA reductase FabI as a prime molecular target of batumin was rejected. However, indirect inhibition of fatty acid biosynthesis in sensitive bacteria does take place as a part of stringent response repression triggered by accumulation of uncharged tRNA molecules. Paralogues of diverse leucine-tRNA synthetases in the genome of P. batumici indicated that this protein might be the prime target of batumin. A batumin biosynthesis operon comprising 28 genes was found to be acquired through horizontal gene transfer. It was hypothesised that, in contrast to mupirocin, batumin could inhibit a broader range of aminoacyl tRNA synthetases and that acquired resistance to mupirocin might not endow S. aureus strains with resistance against batumin.

Abstract B89: The significance of Vitamin D deficiency and anaerobes in prostate cancer

Abstract Objective: Long-term sun exposure estimates correlate with risk of PC possibly due to long-term Vitamin D deficiency diminishing macrophage function allowing persistence of low grade pathogens causing chronic inflammation leading to Proliferative Inflammatory Atrophy and then cancer. Recently infection with two low grade pathogenic organisms, teenage acne associated Vitamin D sensitive anaerobic bacterium Propionibacterium.acnes (PA) and protozoan Trichomonas vaginalis (TA), have been notable exceptions. This presentation reports a systematic review of reports on anaerobes, circumcision and the association of sun exposure in causation of PC and considers how these observations could contributing to increased PC in Africa Methods: Pubmed searches using terms prostate or prostatic, sunshine or UVB or Vitamin D and acne or PA or TA were performed Results: Two systematic reviews of PC and Vitamin D failed to produce a consistent association. 4/4 studies of index of long-term sun exposure involving 1568 patients and 9/12 geographic studies demonstrated that high UVB exposure reduced PC risk. 4/5 publications on PA and PC and 2/3 publications on TV and PC showed consistent increase risk of PC associated with infection. Ten studies involving 5681 patients demonstrated significant reduction of PC in circumcised individuals (OR 0.87), including one in African American Men showing lower incidence of circumcision possibly contributing to their higher frequency Conclusion: Reduced long-term Vitamin D mediated non-specific macrophage surveillance against low-grade pathogenic anaerobes could explain these associations with PC and increasing urbanisation could be a factor in the health inequality as measured by prostate cancer incidence in African-American men. Citation Format: Tim Oliver, Lucy Blackburn, Frank Chinegwundoh. The significance of Vitamin D deficiency and anaerobes in prostate cancer. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr B89.

Commercial Lawsonia inermis L. dried leaves and processed powder: Phytochemical composition, antioxidant, antibacterial, and allelopathic activities

Henna (Lawsonia inermis L.) is a plant used over the world for centuries for its medical and cosmetic virtues. The present work aimed to determine the phytochemical composition, antioxidant, antibacterial activities and phytotoxic potentials of commonly commercialized henna’s dried leaves (HL) and processed powder (HP). The chromatographic method, using reversed-phase high-performance liquid chromatography, with diode array detection (RP-HPLC–DAD) coupled to electrospray ionization–mass spectrometry (ESI–MS), showed that HP and HL contained high polyphenolic content estimated to 31.35±2.05 and 20.22±0.23mg/g of dray starting material, respectively. Gallic acid (16.23%) and eugenol (13.74%) were the most abundant compounds, whereas, luteolin was the major compound in HL (43.41%). Additionally, HP extract showed the strongest antioxidant potentials as assessed by both DPPH and ABTS functional methods with IC50=51.36±1.9 and 78.18±1.47μg/ml, respectively. Antimicrobial potential evaluated using a range of microorganism strains demonstrated that Bacillus subtilis (ATCC6633) was the most sensitive bacteria to both HL and HP extracts with MBC≈165.8±3.7μg/ml (HP) and 454.3±42μg/ml (HL). The extracts allelopathic activity on seed germination, stem and root growth of wheat (Triticum aestivum L.) and canary grass (Phalaris canariensis L.) were also assessed in-vitro. Canary grass was the most sensitive species to HL and HP. Both extracts were effective inhibitors of germination, stem and root growth in a dose-dependent manner. These findings could support the potential applications of HL and HP extracts as natural herbicide. Obtained data reveal that commercial HP contained an additional product that strengthened its chemical and functional properties, particularly, clove (Syzygium aromaticum) which is frequently supplemented for henna’s cosmetic value improvement.

Characterization and management of autochthonous bacterial strains from semiarid soils of Spain and their interactions with fermented agrowastes to improve drought tolerance in native shrub species

Three bacterial autochthonous strains, namely Enterobacter sp.; Bacillus thuringiensis and Bacillus sp. were isolated from the rhizosphere of Mediterranean shrub species growing in a semiarid environment and analyzed alongside with the allochthonous Bacillus megaterium, used as reference drought tolerant strain, for their drought tolerance and plant growth promoting rhizobacteria (PGPR) capacities. The preliminary studies, done in axenic culture under non-stress and stress conditions show that Enterobacter sp. resulted in the most tolerant bacteria to osmotic stress factors. In contrast, Bacillus sp. was the most sensitive bacteria to osmotic stress factors and concomitantly, under these conditions, produced the highest amounts of ACC deaminase, poly-β-hydroxybutyrate and proline, to compensate its lack of stress tolerance. The PGPR activities of the tested bacterial strains under non-osmotic and osmotic stress conditions were determined by evaluating hormone (SA, ABA, JA and IAA) and ACC-deaminase production and phosphate solubilization. To analyze the bacterial efficiency as inoculants four shrubs species (Thymus vulgaris, Santolina chamaecyparissus, Lavandula dentata and Salvia officinalis), adapted to aridity, were selected. All the tested bacteria improved nutrition and physiological variables related to drought tolerance of the test plant. In addition, in S. chamaecyparissus and S. officinalis also increased mycorrhizal colonization. The application of fermented agrowaste resulted in effectively improving nutrient uptake and also interacted positively with most of the bacteria increasing plant nutrients content and drought tolerance but their effectiveness depended on the plant species and bacteria involved. In fact, in B. megaterium and the fermented agrowaste increased P and K uptake in S. chamaecyparissus (by 109% P and by 66% K), in L. dentata (by 75% P and 33% K) and in S. officinalis (by 63% P and 52% K). However, without amendment, the native B. thuringiensis was the most efficient strain in increasing P content in T. vulgaris (by 51%) and in S. chamaecyparissus (by 11%), and K content in L. dentata (by 63%), which decreased the stomatal conductance. Results show that under axenic conditions the stress applied did not suppress the PGPR abilities of assayed bacteria which indicated their potential to be tested as inoculants under detrimental conditions. The applied treatments resulted fundamental for these shrubs to reach their optimal nutritional and physiological traits suggesting their possible applicability under the natural semiarid drought conditions. The multiplicity and complexity of bacterial activities and the intrinsic characteristics of plant reactions to drought could explain the unpredictable results obtained by using these bacteria as plant inoculants. These and other factors are controlling the PGPR effects therefore it made difficult to generalize and to explain the cause/effect of the variable responses to be obtained. The results suggest the potentiality of the target bacteria and fermented agrowaste to be used as a biotechnological tool to help plants and reforestation in semiarid lands.

Antimicrobial Effects of Blueberry, Raspberry, and Strawberry Aqueous Extracts and their Effects on Virulence Gene Expression in Vibrio cholerae.

The antimicrobial effects of aqueous extracts of blueberry, raspberry, and strawberry on 13 pathogenic bacteria were evaluated. The minimum inhibitory concentrations and minimum bactericidal concentrations of the extracts were determined before and after neutralization to pH 7.03 ± 0.15. Both Gram-positive and Gram-negative pathogenic bacteria were selectively inhibited by the non-neutralized berries. Blueberry was the best inhibitor, and Vibrio and Listeria were the most sensitive bacteria. After neutralization, blueberry affected only Vibrio and Listeria, whereas the antimicrobial activities of raspberry and strawberry were abolished. The total contents of phenolics, flavonoids, and proanthocyanidins in the extracts were measured with colorimetric methods and were highest in strawberry, followed by raspberry, and then blueberry. We also studied the effects of sub-bactericidal concentrations of the three berry extracts on virulence gene expression in Vibrio cholerae. Real-time quantitative reverse transcription-polymerase chain reaction revealed that the three berry extracts effectively repressed the transcription of the tcpA gene. Raspberry also repressed the transcription of the ctxA gene, whereas blueberry and strawberry did not. However, the three berry extracts did not affect the transcription of toxT. These results suggest that the three berry extracts exert potent antimicrobial effects and inhibit the expression of the virulence factors of V. cholerae.

The bacterial microflora of diabetic foot infection and factors determining its spectrum in Ouagadougou (Burkina Faso)

The aim of the study was to describe the bacterial microflora of diabetic foot infection and to identify the factors which determine the bacterial spectrum in order to increase empiric antibiotic prescription in Ouagadougou. The study was a cross-sectional one, carried from July 1st, 2011 to June 30, 2012 in the departments of internal medicine and general and digestive surgery in Yalgado Ouédraogo teaching hospital. Samples for bacteriological tests consisted of aspiration of pus through the healthy skin, curettage and swab of the base of the ulceration or tissue biopsy from foot lesions. The bacteria's sensitivity to antibiotics has been tested by the qualitative method (Kirby-Bauer). The frequency of diabetic foot infection was 14.45% and the monthly incidence 5.33. The mean age of patients was 56 years and the sex ratio 1.37. Foot ulcerations were chronic in 33 (51.56%), necrotic in 51 (79.69%) and associated with osteitis in 40 (62.5%) patients. Infection was grade 3 in 70.3% cases. Thirty-nine patients had received antibiotics before hospital admission. Among the 71 samples, 62 (87.32%) cultures were positive: 53 (85.48%) monomicrobial and 9 (14.52%) bimicrobial. Aerobic Gram-positive cocci (76%) were the most frequent from ulcerations: Staphylococcus aureus (32.39%), Streptococcus sp (18.30%). Negative coagulase staphylococci have been found in 23.94% cases. Aerobic gram-negative bacilli have been isolated from 24% ulcerations. No factor was associated with the type of bacteria. Gram-positive pathogen cocci showed a high sensitivity to amoxicillin-clavulanic acid and oxacillin. No methicillin-resistant Staphylococcus aureus (MRSA) or extended-spectrum beta lactamase Enterobacteriaceae (ESBL) have been isolated. A better design is necessary to a clarification of bacterial flora in diabetic foot infections. Prevention of bacterial resistance is also needed.

Antifungal, antibacterial and anticancer activities of Ficus drupacea L. stem bark extract and biologically active isolated compounds

Ficus drupacea is a widely distributed species with ethnopharmacological applications. Despite the large body of literature on its antioxidant and phenolic contents, several aspects of its biological activities remain unexplored. In this study, the antimicrobial (fungi and bacteria) and antiproliferative activities of crude extracts of the plant’s stem bark and isolated compounds were investigated. Seven biochemical compounds from stem bark extracts including β-amyrin (1), β-sitosterol-3-O-β-D-glucopyranoside (2), 5-O-methyllatifolin (3), oleanolic acid (4), epifriedelanol (5), friedelin (6) and epilupeol acetate (7) were isolated and identified. Of all the seven compounds, the compounds 3 and 7 exhibited the highest antifungal and antibacterial activities against screened microorganisms. Aspergillus versicolor and A. ochraceus were the most sensitive microorganisms to the isolated compounds whereas Candida albicans was the most resistant fungus. Compounds 4, 5, and 6 did not exhibit much variation in their antibacterial activities except against Staphylococcus aureus and Escherichia coli. The most sensitive bacterium to isolated compounds was Bacillus cereus whereas the most resistant one was Enterobacter cloacae. However, compounds 4, 6 and 7 exhibited the highest antiproliferative activities against most cancer cells. The study reveal that F. drupacea stem barks contain several compounds that have antimicrobial activities against diverse human pathogenic, food and agricultural microbes as well as anticancer activities against human cancer cells of HeLa, MCF-7, Jurkat, HT-29 and T24. These results may guide the search for new natural products with chemotherapeutic attributes.

Efficacy of Ultraviolet (UV-C) Light in a Thin-Film Turbulent Flow for the Reduction of Milkborne Pathogens

Nonthermal technologies are being investigated as viable alternatives to, or supplemental utilization, with thermal pasteurization in the food-processing industry. In this study, the effect of ultraviolet (UV)-C light on the inactivation of seven milkborne pathogens (Listeria monocytogenes, Serratia marcescens, Salmonella Senftenberg, Yersinia enterocolitica, Aeromonas hydrophila, Escherichia coli, and Staphylococcus aureus) was evaluated. The pathogens were suspended in ultra-high-temperature whole milk and treated at UV doses between 0 and 5000 J/L at a flow rate of 4300 L/h in a thin-film turbulent flow-through pilot system. Of the seven milkborne pathogens tested, L. monocytogenes was the most UV resistant, requiring 2000 J/L of UV-C exposure to reach a 5-log reduction. The most sensitive bacterium was S. aureus, requiring only 1450 J/L to reach a 5-log reduction. This study demonstrated that the survival curves were nonlinear. Sigmoidal inactivation curves were observed for all tested bacterial strains. Nonlinear modeling of the inactivation data was a better fit than the traditional log-linear approach. Results obtained from this study indicate that UV illumination has the potential to be used as a nonthermal method to reduce microorganism populations in milk.

The extract of Hypericum ascyron L. induces bacterial cell death through apoptosis pathway

Ethnopharmacological relevanceHypericum ascyron L. (H. ascyron L.) has been used as a traditional medicine for the treatment of wounds, swelling, headache, nausea, stomach ache, abscesses, dysentery and chronic bronchitis. Pharmacological studies are necessary to provide a scientific basis to substantiate their traditional use. In this study, antimicrobial effect and its mechanism of the H. ascyron L. extract was investigated. Materials and methodsAntimicrobial activity of the H. ascyron L. extract was evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT). To confirm the antimicrobial mechanism of H. ascyron L. extract on bacterial cells, Annexin V/propidium iodide (PI) double staining, TUNEL, and DNA laddering analysis were performed. ResultsAntibacterial effects of the H. ascyron L. extract were tested on Enterobacter cloacae, Klebsiella pneumonia, Escherichia coli, Staphylococcus aureus and Micrococcus luteus, and the results showed that the sensitive bacteria of H. ascyron L. extract mainly included E. coli, S. aureus and M. luteus, especially M. luteus. The MBC value of H. ascyron L. extract on M. luteus was equal to the MIC (20mg/mL). H. ascyron L. extract could induce cells death of M. luteus through apoptosis pathway. ConclusionsThis study provides scientific support for some of the traditional uses and the pharmacological activities of H. ascyron L. Our data provide a rational base for the folkloric use of H. ascyron L.