Agar Growth Medium Research Articles

A study on twitching motility dynamics in Ralstonia solanacearum microcolonies by live imaging.

Ralstonia solanacearum is a rod-shaped phytopathogenic bacterium that causes lethal wilt disease in many plants. On solid agar growth medium, in the early hour of the growth of the bacterial colony, the type IV pili-mediated twitching motility, which is important for its virulence and biofilm formation, is prominently observed under the microscope. In this study, we have done a detailed observation of twitching motility in R. solanacearum colony. In the beginning, twitching motility in the microcolonies was observed as a density-dependent phenomenon that influences the shape of the microcolonies. No such phenomenon was observed in Escherichia coli, where twitching motility is absent. In the early phase of colony growth, twitching motility exhibited by the cells at the peripheral region of the colony was more prominent than the cells toward the center of the colony. Using time-lapse photography and merging the obtained photomicrographs into a video, twitching motility was observed as an intermittent phenomenon that progresses in layers in all directions as finger-like projections at the peripheral region of a bacterial colony. Each layer of bacteria twitches on top of the other and produces a multilayered film-like appearance. We found that the duration between the emergence of each layer diminishes progressively as the colony becomes older. This study on twitching motility demonstrates distinctly heterogeneity among the cells within a colony regarding their dynamics and the influence of microcolonies on each other regarding their morphology.

Investigating the Presence of Efflux Pump Genes adeI and adeJ in Clinical Antibiotic-Resistant Isolates of Acinetobacter baumannii

Background: Acinetobacter baumannii is one of the most important known causes of hospital infections worldwide that is resistant to many common antibiotics. Efflux pumps are among the main reasons behind resistance in this bacterium. Objectives: This study was conducted to investigate the presence of efflux pump genes (adeI, adeJ) in clinical antibiotic-resistant isolates of A. baumannii in Tehran hospitals. Methods: One hundred fifty clinical samples of wounds, urine, sputum, and blood were collected periodically (6 months) from Tehran hospitals. Acinetobacter baumannii was identified using common biochemical methods. After conducting biochemical tests, the final confirmation of the samples was performed by examining the blaOXA-51-like gene by molecular polymerase chain reaction (PCR) method. The disk diffusion antimicrobial susceptibility testing was performed using Mueller Hinton agar growth medium according to Clinical and Laboratory Standards Institute (CLSI) guidelines on nine antibiotics. Then the samples were investigated for the presence of adeI and adeJ genes. Results: Examining the antibiotic resistance of the isolates showed that the resistance level varied from 48.1% to 98.2%, depending on the antibiotic type. In this study, isolates showed the highest and lowest resistance to tetracycline and gentamicin, respectively. Also, positive isolates for the presence of adeI and adeJ genes showed the highest resistance to tetracycline, amikamycin, ceftazidime, and ceftriaxone. Isolates that were negative for the presence of these two genes showed the highest sensitivity to imipenem, gentamicin, and ciprofloxacin. Conclusions: In this study, the correlation of antibiotic resistance test and PCR results showed that the presence of adeI and adeJ genes in the samples significantly increased the resistance to all investigated antibiotics. Therefore, evaluating efflux pumps proves to be useful in identifying antibiotic-resistant strains and appropriate drug treatment. Of course, the role of other factors in creating resistance should not be neglected.

Изучение экзогенных репродуктивных структур аксенической культуры гриба спорыньи (Claviceps Purpurea) в процессе бесполого размножения

Claviceps purpurea (Fries) Tulasne are used in parasitic and saprophytic cultures to obtain ergoalkaloids (EA), including ergocriptine. Ergocryptine has a variety of pharmacological effects, including reducing the secretion of prolactin and somatotropic hormone, suppresses physiological lactation. It also has an antiparkinsonian effect, and ergocriptine increases motor activity. Ergocriptine- based drugs are used in the treatment of hyperprolactinemia and adenomas that produce prolactin, infertility in men and women. The importance of C. purpurea for medicine requires the study of reproduction characteristics of the fungus cultivated in different areas and substrates. The results of studying features of the exogenous reproductive structures the ergocriptine line fungus Claviceps purpurea in saprophytic condition, as well as the composition of ergot alkaloids in sclerotia and in samples of C. purpurea mycelia, are presented. The exogenous reproductive structures play a decisive role in artificial infection in saprophytic and parasitic conditions. The aim of the work was to study the growth and reproductive in saprophytic of the line of the fungus parasite C. purpurea producing ergocriptine in saprophytic conditions under the conditions of saprophytic cultivation (by surface and submerged methods cultivation). It was found that the growth rate of conidia, including width and length, were faster under the conditions of saprophytic cultivation of C. purpurea on the surface of an agar growth medium. The features of the dynamics of conidioproduction in submerged and surface cultivation on an agar growth medium. It has been shown that the HPLC method, in comparison with TLC for the analysis of ergocriptine, is more effective, since it allows the determination of its insignificant content.

Quality and Safety Assessment of Edible Seaweeds Alaria esculenta and Saccharina latissima Cultivated in Scotland.

Within Europe over the last 10 years, there has been an increase in seaweeds cultivated for human consumption. For food safety reasons, it is important to assess the microbiological and nutritional quality of the biomass. The fresh and dried edible seaweeds Alaria esculenta and Saccharina latissima were assessed over two consecutive years for the presence of microorganisms. Seaweed samples supplied from Scotland were stored under isothermal conditions for specific time intervals depending on the sample’s condition (fresh, dried or rehydrated). During storage, microbiological analyses were performed for the enumeration of Total Viable Counts (TVC), Pseudomonas spp., Enterobacteriaceae and Bacillus spp., as well as yeasts and molds. Additionally, bacterial colonies from the Marine Agar growth medium were isolated and subjected to PCR-RAPD analysis for characterization of the bacterial diversity of seaweeds. Bacterial isolates with different fingerprint patterns were further subjected to sequencing (16S rDNA, V1–V4 region). The presence of human pathogenic bacteria was also investigated. Results showed that the initial population of TVC was differentiated depending on the year of seaweed harvest, being closer to the enumeration limit (1.0 log CFU/g) in fresh samples from 2020 and higher in samples from 2019 (6.7 and 3.9 log CFU/g in A. esculenta and S. latissima, respectively). DNA-based analysis revealed the presence of Psychrobacter, Cobetia and Pseudomonas species in A. esculenta, while Psychrobacter and Micrococcus species were present in S. latissima.

Diversity and characteristics of culturable endophytic bacteria from Passiflora edulis seeds.

Defense compounds generally inhibit microbial colonization of plants. In this study, we examined the presence of endophytes in Passiflora edulis seeds that accumulate resveratrol and piceatannol at extremely high levels as defense compounds. Interestingly, although no microbial colonies appeared on an agar growth medium from the cut or homogenized seeds, colonies were generated from cut seedlings derived from the seeds. A total of 19 bacterial strains were isolated, of which 15 were classified as Gram‐positive. As we hypothesized that extremely high levels of piceatannol in the seeds would inhibit the growth of endophytes cultured directly from the seeds, we examined the antimicrobial activity of this compound against the isolated bacteria. Piceatannol exerted bacteriostatic rather than bactericidal effects on most of the bacteria tested. These results suggest that the bacteria remain static in the seeds due to the presence of piceatannol and are transmitted to the seedlings during the germination process, enabling colonies to be established from the seedlings on the agar medium. We also investigated the biocatalytic activity of the isolated bacteria toward resveratrol and piceatannol. One bacterium, Brevibacterium sp. PE28‐2, converted resveratrol and piceatannol to their respective derivatives. This strain is the first endophyte shown to exhibit such activity.

Features of iron accumulation at high concentration in pulcherrimin-producing Metschnikowia yeast biomass.

In previous studies it was found that the antimicrobial properties of pulcherrimin-producing Metschnikowia species are related to the formation of a red pigment-pulcherrimin and sequestration of free iron from their growth medium. For strains of Metschnikowia pulcherrima, M. sinensis, M. shaxiensis, and M. fructicola, at a high, ≈80mg/kg, elemental Fe concentration in agar growth media we observed the essentially different (metal luster, non-glossy rust like, and colored) yeast biomass coatings. For the studied strains the optical and scanning electron microscopies showed the increased formation of chlamydospores that accumulate a red pigment-insoluble pulcherrimin rich in iron. The chlamydospore formation and decay depended on the iron concentration. In this study pulcherrimin in biomass of the selected Metschnikowia strains was detected by Mössbauer spectroscopy. At ≈80mg/kg elemental Fe concentration the Mössbauer spectra of biomass of the studied strains were almost identical to these of purified pulcherrimin. Iron in pulcherrimin reached ≈1% of biomass by weight which is very high in comparison with elemental Fe percentage in growth medium and is not necessary for yeast growth. The pulcherrimin in biomass was also observed by Mössbauer spectroscopy at lower, ≈5mg/kg, elemental Fe concentration. Through chemical binding of iron pulcherrimin sequestrates the soluble Fe in the growth media. However, at high Fe concentrations, the chemical and biochemical processes lead to the pulcherrimin accumulation in biomass chlamydospores. When soluble iron is sequestrated or removed from the growth media in this way, it becomes inaccessible for other microorganisms.

IMPACT OF CORONA DISCHARGE ON ASPERGILLUS NIGER SPORES AND CYATHUS OLLA MYCELIUM GROWTH

The article presents an investigation of the influence of the corona discharge with needle-ring electrode configuration on the efficiency of Aspergillus niger spore germination and Cyathus olla mycelium development. Current-voltage characteristics were measured for different distances between the needle and the metal ring. The plot of the dependence of conductance on voltage was built and the corona discharge breakthrough voltage was determined to be (2.7±0.1) kV. The treatment of Aspergillus niger spores was conducted at different development stages: at the germination stage (corona discharge treatment 1 day after the seeding) and dormant state (corona discharge treatment on the day of seeding). The growth rate of Cyathus olla mycelium in samples treated by corona discharge and in control group samples was investigated. The influence of the corona discharge on the potato dextrose agar growth medium before the seeding of Cyathus olla was studied. The pure cultures were obtained from the Culture Collection of Fungi at Kyiv University (FCKU) at the «Institute of Biology and Medicine» Educational and Scientific Centre of the Taras Shevchenko National University of Kyiv.

An inexpensive, high-throughput μPAD assay of microbial growth rate and motility on solid surfaces using Saccharomyces cerevisiae and Escherichia coli as model organisms.

Many microbial phenotypes are differentially or exclusively expressed on agar surfaces, including biofilms, motility, and sociality. However, agar-based assays are limited by their low throughput, which increases costs, lab waste, space requirements, and the time required to conduct experiments. Here, we demonstrate the use of wax-printed microfluidic paper-based analytical devices (μPADs) to measure linear growth rate of microbes on an agar growth media as a means of circumventing the aforementioned limitations. The main production materials of the proposed μPAD design are a wax printer, filter paper, and empty pipet boxes. A single wax-printed μPAD allowing 8 independent, agar-grown colonies costs $0.07, compared to $0.20 and $9.37 for the same number of replicates on traditional microtiter/spectrophotometry and Petri dish assays, respectively. We optimized the μPAD design for channel width (3 mm), agar volume (780 μL/channel), and microbe inoculation method (razor-blade). Comparative analyses of the traditional and proposed μPAD methods for measuring growth rate of nonmotile (Saccharomyces cerevisiae) and motile (flagellated Escherichia coli) microorganisms suggested the μPAD assays conferred a comparable degree of accuracy and reliability to growth rate measurements as their traditional counterparts. We substantiated this claim with strong, positive correlations between the traditional and μPAD assay, a significant nonzero slope in the model relating the two assays, a nonsignificant difference between the relative standard errors of the two techniques, and an analysis of inter-device reliability. Therefore, μPAD designs merit consideration for the development of enhanced-throughput, low-cost microbial growth and motility assays.

Selective synthetic growth medium “Acinetobacter phenylalanine agar” for isolation and identification of Acinetobacter calcoaceticus — Acinetobacter baumannii complex species

The aim of the study was to carry out clinical and microbiological testing of selective growth medium Acinetobacter phenylalanine agar to isolate and identify bacterial species belonging to the Acinetobacter calcoaceticus — Acinetobacter baumannii complex (ACB complex). For this, 400 samples of clinical material (wound discharge, blood, urine, bronchoalveolar lavage) were examined in 2018 in the Clinical and Bacteriological Laboratory of the Military Medical Academy by using routine assays (seeding on blood agar growth medium, pure culture isolation and identification by using biochemical assays as well as VITEK 2 microbial identification system, bioMerieux) and plating together with growth medium Acinetobacter phenylalanine agar selective to Acinetobacter spp. owing to L-phenylalanine as a sole nitrogen and carbon source additional selected with trimethoprim. ACB complex Acinetobacters were identified 18–24 hours later after incubation at 37°C by emergence of typical colonies on selective medium. Control tests for cytochrome oxidase as well as oxidative/fermentation (OF)-glucose test by using peroxide-hydrogen microvolume method (for 1 h) allowed to rapidly distinguish ACB complex Acinetobacters from other bacteria as well as from Acinetobacter spp. unable to glucose oxidation. Next, species identity for all isolated Acinetobacter strains was established by using matrix-activated laser desorption/ionization with time-of-flight mass spectrometry (MALDI-TOF MS). It was found that by using novel vs. routine assay Acinetobacter spps. were isolated in 26 (18 samples — in monoculture, 8 — in association with Pseudomonas aeruginosa or Klebsiella pneumoniae subsp. pneumoniae with tiny associate colonies) vs. 20 (7 — in monoculture, 13 — in association with Pseudomonas aeruginosa, Klebsiella, Escherichia, Citrobacter, Providencia, Staphylococcus, Enterococcus, C. albicans). Using MALDI-TOF MS method revealed that 25 out of 26 Acinetobacter strains isolated on selective growth medium belonged to the ACB complex (A. baumannii — 23, A. pittii — 2), whereas one strain (A. baylyi) did not belong to ACB complex. Hence, the diagnostic specificity of the Acinetobacter phenylalanine agar synthetic growth medium for isolation and identification of the A. calcoaceticus — A. baumannii complex species comprised 96.2%, with diagnostic sensitivity exceeding that one for routine assay by 25%. Use of selective growth medium accelerates research by allowing to isolate and identify ACB complex Acinetobacter spp. 18–24 h later after plating clinical material. Selectivity of growth medium was potentially stable, as its major trophic selection factor did not depend on acquired bacterial antibiotic resistance, which is also suitable as a synthetic growth medium for standardized studies.

A comprehensive guide to dynamic analysis of microbial gene expression using the 3D-printed PFIbox and a fluorescent reporter library.

Temporally resolved assays of bacterial gene expression using printed fluorescence imaging boxes (PFIboxes) are non-destructive, inexpensive and simple to prepare. Herein, we describe a full experimental pipeline wherein PFIbox parts are modified and 3D printed, electronics assembled and used to study transcriptional responses of Escherichia coli to chemical stressors. A chemical probe is added to agar growth medium, and a promoter-fluorophore fusion library is arrayed in high density on the agar slab. With high temporal resolution, the reporter library is imaged in PFIboxes, then quantified using promoter activity as a measure of gene expression. PFIboxes have advantages over conventional transcriptomic approaches such as RNA-seq, as the non-destructive nature permits a high-resolution temporal dimension in the data. This results in rapid measurement of transcriptional responses to chemical or physical stimuli. Each time-course gene expression assay costs about US$2 to run, in triplicate, using this method. Printing time depends on printer and settings, but once printed, PFIboxes can be fully assembled, programmed and loaded with samples in less than 1 h. Experimental durations and sampling frequency are set according to user need, but can be run in the duration of a microbial growth curve.

The mould resistance of carbide lime by-products from deposits

The article deals with testing and evaluating the mould resistance of carbide lime by-product from deposits in comparison with the effect of reference conventional slaked lime. The mould resistance of limes was tested on a mixture of mould such as Gliocladium virens, Paecilomyces variotii, Penicillium funiculosum, Chaetomium globosum, and Aspergillus niger as well as evaluated according to the method stated in the technical standard STN 724310: 1993. The evaluating scale for mould resistance is from 0 up to 5 in the fungal growth degree (FGD). The FGD value 0 stands for no fungal growth comes about and construction materials and products have the microbiostatic effect against filamentous fungi. The experiments confirm the microbiostatic effect against mould of carbide lime by-product from deposits as well as reference conventional slaked lime; however, the microbicidal effect against mould has not been confirmed at all; the inhibiting area—zone—did not form on the agar growth media around the tested samples. Application of carbide lime by-product from deposits ensures increased mould resistance of construction materials with the microbiostatic effect against mould in accordance with technical standard STN 724310: 1993.

A Survey of Symptoms of Fungal Disease in Sugarcane (Saccharum officinarum L.) in Buea, in the South West Region of Cameroon

Aim: Sugarcane (Saccharum officinarum L.) which is mostly cultivated in tropical and subtropical regions of the world is an important source of sucrose. This crop which was originally grown in South Eastern Asia and the Pacific for the sole purpose of chewing is mainly used nowadays for the production of sugar, bio-fuels, medicine etc. In spite of its numerous uses, the production of sugarcane in Buea, South West region of Cameroon is hampered by many factors including the incidence of disease. It is possible that some varieties are no longer cultivated because of their susceptibility to fungal diseases. It was for these reasons that we decided to survey the sugarcane farms in this area, to evaluate the presence of diseased symptoms due to activity of fungi.
 Study Design: Random sampling.
 Place and Duration of Study: Buea and its environs, Rubber Pathology Laboratory IRAD Ekona, and Life Sciences Laboratory, University of Buea, between June 2016 and July 2017.
 Methodology: During the survey, sugarcane farms in five villages in Buea and its environments were visited. The leaves and stems of the plants were observed for any symptoms of fungal activity. The incidence, severity and prevalence of the symptoms were noted. Leaf samples were collected from diseased sugarcane plants and transported to the laboratory for the isolation of fungi on Potato Dextrose Agar growth medium. The isolates were identified based on their cultural and micro-morphological characteristics.
 Results: Sugarcane plants with fungal disease symptoms were seen in all the farms visited during the survey, thus a prevalence of 100%. The disease incidence varied from 54- 100%, while the severity ranged from 20- 55%. Two genera of fungi were isolated from the diseased plants viz: Chaetomium sp. and Bipolaris sp. 
 Conclusion: Chaetomium and Bipolaris are associated with fungal symptoms in diseased sugarcanes hence any management plans geared towards the improvement of sugarcane production in this area must include control measures for these fungi.

Bacterial Contamination of Military and Civilian Uniforms in an Emergency Department

IntroductionThe emergency department is a fast-paced, high-volume environment, serving patients with diverse and evolving acuities. Personnel providing direct care are continually exposed to pathogenic microorganisms from patients and everyday surfaces, to which the organisms may spread. Indeed, hospital items—such as electronic devices, stethoscopes, and staff clothing—have demonstrated high rates of contamination. Despite this, policies governing the use, disinfection, and wear of various environmental surfaces remain relaxed, vague, and/or difficult to enforce. This study aimed to examine the bacterial contamination on 2 hospital uniform types in a large military hospital within the emergency department. MethodsEnvironmental sampling of military and civilian nursing staff uniforms was performed on 2 separate occasions. Emergency nurses wore hospital-provided freshly laundered scrubs on the first sampling day and home-laundered personally owned uniforms complicit with ED policy on the second sampling day. Samples were collected by impressing of contact blood agar growth medium at arrival (0 hour), 4 hours, and 8 hours of wear. Microbiological methods were used to enumerate and identify bacterial colonies. ResultsBacterial contamination of personally owned uniforms was significantly higher than freshly laundered hospital-provided scrubs on 4 different sampling sites and across the span of an 8-hour workday. No significant differences were observed between military and civilian personally owned uniforms. However, several risk factors for nosocomial infection were increased in the military subgroup. DiscussionRe-evaluating organizational factors (such as uniform policies) that increase the propensity for pathogenic contamination are critical for mitigating the spread and acquisition of multidrug-resistant organisms in the emergency department.

First Report of Willow Anthracnose Caused by Colletotrichum salicis in Poland.

Growing interest in willow species of the genus Salix as a bioenergy crop has contributed to an increase in willow plantations in Poland (Sulima et al. 2017). In June 2016, terminal bud necrosis was observed in a willow plantation (Salix purpurea, S. vinimalis × S. schwerini) near Olsztyn (Poland). Brown to black discoloration of willow bark at a height of 150 to 170 cm and progressive necrosis of shoots located above the affected area were noted. The symptoms of disease were observed on two to three shoots per plant, and total infection rates in the plantation reached approximately 50 to 70% in S. vinimalis × S. schwerini and 20 to 30% in S. purpurea. Willow shoots (three to five per plant) were sampled in five locations in the plantation to identify the fungus responsible for the disease symptoms. The shoots with healthy, and diseased tissues were cut into 5-mm sections, surface disinfected with 70% ethanol for 1 min and 1% NaOCl, and placed on Petri plates with potato dextrose agar growth medium. The obtained fungal colonies were characterized by gray aerial mycelia, and the cultures contained cylindrical, hyaline, and smooth-walled conidia measuring 11 to 17 × 3 to 5 μm (n = 50). The cultured species was identified as C. acutatum based on its morphological characteristics (Damm et al. 2012). The taxonomic identity of the pathogen was confirmed by isolating DNA from representative strain SP17/2016 with the use of the Maxwell16LEV Plant DNA Kit (Promega, Madison, WI). The identity of the species was confirmed by next-generation sequencing with the use of the MiSeq platform (Illumina, San Diego, CA). The genomic DNA libraries were prepared using the Nextera XT kit (Illumina). The sequences were assembled using Velvet 1.2.10 and were annotated using Augustus 0.1.1, both implemented in Geneious 8.1.9, and were deposited in GenBank. The identification of the isolate to the species level of C. salicis was validated by performing a BLASTn search with six sequences in accordance with polyphasic analysis (Sharma and Shenoy 2016). The following matches were obtained: JFFI01000260.1 (region, 7506 to 7929; protein ID, KXH68653.1) for heat shock factor binding protein 1 (KY745736) with I = 99% and Q = 100%; JFFI01001175.1 (region, 118784 to 119087; protein ID, KXH62418.1) for cytochrome-c oxidase chain VIIc (KY745760) with I = 100% and Q = 100%; JFFI01001268.1 (region, 10848 to 11483; protein ID, KXH61539.1) for ubiquitin-conjugating enzyme E2 35 (KY745744) with I = 99% and Q = 100%; JFFI01001474.1 (region, 60131 to 61160; protein ID, KXH59678.1) for p450 monooxygenase (KY745746) with I = 100% and Q = 100%; JFFI01001277.1 (region, 73500 to 75238; protein ID, KXH59678.1) for glutathione synthetase (KY745725) with I = 99% and Q = 100%; and JFFI01002559.1 (region, 48713 to 49176; protein ID, KXH30318.1) for NADH:ubiquinone oxidoreductase 11.5kD subunit (KY745730) with I = 100% and Q = 100%, where I is “identity” and Q is “query coverage” (queries are our sequences). To confirm pathogenicity, the conidia (1 × 10⁷/ml) of the SP17/2016 isolate, obtained from 14-day cultures exposed to ultraviolet (UV) radiation (in the 12-h dark/12-h UV light cycle), were transferred to the shoots of 1-year-old S. purpurea and S. vinimalis seedlings in a greenhouse experiment (16-h light/8-h dark photoperiod, temperature of 24°C, plants generally watered every other day). The first disease symptoms (necrosis) on shoots were observed around 7 days after the experimental infection. The presence of C. salicis was confirmed by culturing the isolated pathogen, and its species identity was determined based on microscopic observations of morphological features and by qPCR with the use of primers specific for C. acutatum (Debode et al. 2009). To date, willow anthracnose caused by C. acutatum has been reported from California (U.S.A.) (Swain et al. 2012), and C. salicis has been isolated from willows in Germany, New Zealand, and the Netherlands (Damm et al. 2012). This is the first report documenting the presence of C. salicis, the causative agent of willow anthracnose, in Poland.

Antimicrobial Efficiency of Metallurgical Slags for Application in Building Materials and Products

The article deals with studying the antimicrobial efficiency of finely ground metallurgical slags, such as granulated blast-furnace slag with specific surface areas of 340 (1Sa) and 520 m2/kg (1Sb), air cooled blast-furnace slag (2S), demetallized steel slag (3S), calcareous ladle slag (4S), and copper slag (5S). The efficiency was tested on microbial representatives, such as: Gram-positive bacteria—Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus; Gram-negative bacteria—Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens; yeasts—Candida utilis, Rhodotorula glutinis; and microscopic filamentous fungi—Aspergillus niger, Penicillium funiculosum, Chaetomium globosum, Alternaria alternata, Trichoderma viride, Cladosporium herbarum. The efficiency was determined by dilution methods in agar growth media so that the resulting concentration of the tested slags was 10, 20, 40, and 60%. The antibacterial efficiency of the slags decreased in the order: S4 > S3 > S2 > S1a = S1b > S5, while their anti-yeast efficiency decreased in the order S4 > S1a = S1b = S3 > S2 > S5. Microscopic filamentous fungi were selectively sensitive to the slags; therefore, there is only an approximate order of efficiency of S4 > S3 = S1a = S1b > S5 > S2. Application of metallurgical slags into building materials and products provide them with increasing resistance against biodeterioration.

Surgical Site Irrigation in Plastic Surgery

The incidence of infection following breast implant reconstruction remains high at the level of 24%. Surgical site irrigation is commonly used for its prevention. However, the lack of evidence-based guidelines for antibiotic prophylaxis in breast implant surgery necessitates research for optimal irrigation technique. composition and exposure time of irrigation solution for surgical site infection (SSI) prophylaxis using an in vitro model of a surgical site. The study design was an in vitro model to assess antibiotic irrigation of a surgical site. Strains of Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Group A Streptococcus, and Pseudomonas aeruginosa were seeded on blood agar growth medium and irrigated with various antibiotic and antiseptic solutions under different exposure times. The presence and quantity of the colonies grown were estimated after 24-hour incubation. Repetition of the studies for 5 times with each investigated irrigation solution and microorganism was performed. Optimal irrigation agents were chosen based on the ability to achieve sterility with minimal tissue toxicity. The optimal wound irrigation agents for SSI prophylaxis in our study were found to be 0.05% chlorhexidine or triple antibiotic antibiotic solutions. Adding of vancomycin to the irrigation solutions did not show an increase in their effectiveness. Prolonged irrigation exposure time was necessary to achieve sterility of the in vitro model of a surgical site. We recommend 0.05% chlorhexidine or triple antibiotic solution for topical SSI prophylaxis in breast implant surgery. Sufficient time of irrigation can be achieved by maintaining some of the solution in the pocket and delaying drainage for at least 30 minutes.

Different Behavior and Response of Staphylococcus Epidermidis and Streptococcus Pneumoniae to a Ventriculoperitoneal Shunt: An in vitro Study

Background: Pneumococcal shunt infection is a rare event. There is no consensus on the therapeutic management of this kind of shunt infection according to literature reviews, and it seems to be different from infection with Staphylococcus epidermidis. We studied 2 shunted patients with pneumococcal meningitis, both of whom were treated with only antibiotics. The management of these cases seems to be different from that of shunt catheter infection due to these bacteria. We conducted a laboratory study to show the different behavior of pneumococcus compared to S. epidermidis regarding shunt catheter colonization. Materials and Methods:S. epidermidis and Streptococcus pneumoniae bacteria isolated from the cerebrospinal fluid of meningitis patients were incubated in sterile media. Forty-five segments of shunt catheter from silicone material were placed in 45 separate media of S. epidermidis and pneumococcus. Then each catheter was washed and cultured in blood chocolate agar growth medium in separate petri dishes via the roll plate method. The dishes were extracted from the incubator and the colony count was calculated after 72 h. Results: The colony count was obviously different between the 2 bacteria groups, with a higher count related to S. epidermidis dishes. The colony count of the pneumococcal petri dishes was 25-35,000 (mean 14,337) and for dishes with S. epidermidis it was 14,000-100,000 (mean 50,125) (p = 0.001). Conclusion: The adherence of pneumococcus to shunt catheters seems to be much less than that of S. epidermidis, which produced a very low colony count when incubated with the catheter in the medium culture. S. pneumoniae meningitis in shunted patients can be managed successfully with only antibiotics. This approach can prevent problems related to the several additional surgeries required for shunt removal, a new shunt insertion, and the management of high intracranial pressure.

Discrimination of bacteria by rapid sensing their metabolic volatiles using an aspiration-type ion mobility spectrometer (a-IMS) and gas chromatography-mass spectrometry GC-MS

The objective of our study was to investigate whether one may quickly and reliably discriminate different microorganism strains by direct monitoring of the headspace atmosphere above their cultures. Headspace samples above a series of in vitro bacterial cultures were directly interrogated using an aspiration type ion mobility spectrometer (a-IMS), which produced distinct profiles (“fingerprints”) of ion currents generated simultaneously by the detectors present inside the ion mobility cell. Data processing and analysis using principal component analysis showed net differences in the responses produced by volatiles emitted by various bacterial strains. Fingerprint assignments were conferred on the basis of product ion mobilities; ions of differing size and mass were deflected in a different degree upon their introduction of a transverse electric field, impacting finally on a series of capacitors (denominated as detectors, or channels) placed in a manner analogous to sensor arrays.Three microorganism strains were investigated – Escherichia coli, Bacillus subtilis and Staphylococcus aureus; all strains possess a relatively low pathogenic character. Samples of air with a 5 cm3 volume from the headspace above the bacterial cultures in agar growth medium were collected using a gas-tight chromatographic syringe and injected inside the closed-loop pneumatic circuit of the breadboard a-IMS instrument model ChemPro-100i (Environics Oy, Finland), at a distance of about 1 cm from the ionization source. The resulting chemical fingerprints were produced within two seconds from the moment of injection. The sampling protocol involved to taking three replicate samples from each of 10 different cultures for a specific strain, during a total period of 72 h after the initial incubation – at 24, 48 and 72 h, respectively. Principal component analysis (PCA) was used to discriminate between the IMS fingerprints. PCA was found to successfully discriminate between bacteria at three levels in the experimental campaign: 1) between blank samples from growth medium and samples from bacterial cultures, 2) between samples from different bacterial strains, and 3) between time evolutions of headspace samples from the same bacterial strain over the 3-day sampling period. Consistent classification between growth medium samples and growth medium inoculated with bacteria was observed in both positive and negative detection/ionization modes.In parallel, headspace air samples of 1 dm3 were collected from each bacterial culture and loaded onto Tenax™-Carbograph desorption tubes, using a custom built sampling unit based on a portable sampling pump. One sample was taken for each of 10 different cultures of a strain, at 24, 48 and 72 h after the initial incubation. These adsorption tubes were subsequently analyzed using thermal desorption – gas chromatography – mass spectrometry (TD-GC-MS). This second dataset was intended to produce a qualitative analysis of the volatiles present in the headspace above the bacterial cultures.

Chromium tolerance, oxidative stress response, morphological characteristics, and FTIR studies of phytopathogenic fungus Sclerotium rolfsii.

Sclerotium rolfsii is one of the most destructive fungal plant pathogens that can infect over 500 plants and can adapt to diverse environmental conditions. The present research work was carried out to evaluate the impact of both hexa- and trivalent chromium (Cr) on growth, morphology, enzymatic characteristics, and metal accumulation in S. rolfsii under laboratory conditions. Experiments were performed in both malt extract broth and agar growth medium amended with six different concentrations (10, 20, 40, 60, 80, and 100ppm) of each Cr(III) and Cr(VI) ions inoculated with fungus and incubated for 6-7days at 25±3°C. In broth medium, the total protein content was declined and activities of antioxidant enzymes were increased with an increase in metal concentrations. Lower concentrations (10ppm) of the metal ions stimulated the growth of fungus and higher concentrations (60-100) inhibited it. The Fourier transform infrared spectroscopy (FTIR) assessment showed hydroxyl, carboxyl, and amine groups as major metal binding sites. In agar medium, tolerance index was decreased up to 0.56 at 10-80ppm of Cr(III) and up to 0.62 at 10-60ppm of Cr(VI). Considerable modifications were observed in hyphal and sclerotial morphology with an increase in concentration of metal ions. The current study concluded that interference of Cr with growth and physiological process of S. rolfsii could affect its infection level on its host plant. This study provides important information regarding cultivation of susceptible plant varieties in Cr-polluted soil as evidenced by pathogen growth up to 50ppm of Cr(III) and Cr(VI) ions.

Extratos de plantas de uso popular contra infecções orais

Objetive: To assess the antibacterial effect of plant extracts of popular use on bacteria related to the development of caries and endodontic infections. Methods: Experimental study conducted at the University of the Extreme South of Santa Catarina in 2015 in which dyes of Artemisia absinthium, Laurus nobilis, Bidens pilosa, Achillea millefolium L and Foeniculum vulgare at hydro-alcoholic concentrations of 5%, 10%, 15% and 20% in Mueller Hinton agar growth-medium had their antibacterial activity against strains of S. mutans and E. faecalis measured. The solid medium diffusion method was used and the inhibitory activity was analyzed according to the presence and size of inhibition halos – control and chlorhexidine 0.12%. Significance level was set at α=0.05. Results: There was no inhibition on the strains of E. faecalis in any of the dyes; however, it was observed an inhibitory effect of Artemisia absinthium, Laurus nobilis and Bidens pilosa dyes on the strains of S. mutans at the concentrations tested. Conclusion: The dyes of plants of popular use assessed showed no antimicrobial effects on E. faecalis, which causes endodontic infections; however, three of them presented inhibitory effects against S. mutans, which is mainly responsible for caries.