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Volume 71 (2022): Issue 3 (September 2022)

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Volume 71 (2022): Issue 1 (March 2022)

Volume 70 (2021): Issue 4 (December 2021)

Volume 70 (2021): Issue 3 (September 2021)

Volume 70 (2021): Issue 2 (June 2021)

Volume 70 (2021): Issue 1 (March 2021)

Volume 69 (2020): Issue 4 (December 2020)

Volume 69 (2020): Issue 3 (September 2020)

Volume 69 (2020): Issue 2 (June 2020)

Volume 69 (2020): Issue 1 (March 2020)

Volume 68 (2019): Issue 4 (January 2019)

Volume 68 (2019): Issue 3 (September 2019)

Volume 68 (2019): Issue 2 (June 2019)

Volume 68 (2019): Issue 1 (March 2019)

Volume 67 (2018): Issue 4 (December 2018)

Volume 67 (2018): Issue 3 (September 2018)

Volume 67 (2018): Issue 2 (June 2018)

Volume 67 (2018): Issue 1 (January 2018)

Volume 66 (2017): Issue 4 (December 2017)

Volume 66 (2017): Issue 3 (September 2017)

Volume 66 (2017): Issue 2 (June 2017)

Volume 66 (2017): Issue 1 (March 2017)

Volume 65 (2016): Issue 4 (December 2016)

Volume 65 (2016): Issue 3 (August 2016)

Volume 65 (2016): Issue 2 (June 2016)

Volume 65 (2016): Issue 1 (March 2016)

Journal Details
Format
Journal
eISSN
2544-4646
First Published
04 Mar 1952
Publication timeframe
4 times per year
Languages
English

Search

Volume 66 (2017): Issue 1 (March 2017)

Journal Details
Format
Journal
eISSN
2544-4646
First Published
04 Mar 1952
Publication timeframe
4 times per year
Languages
English

Search

32 Articles
Open Access

From Latent Tuberculosis Infection to Tuberculosis. News in Diagnostics (QuantiFERON-Plus)

Published Online: 30 Mar 2017
Page range: 5 - 8

Abstract

Abstract

It is estimated that one third of the world’s population have latent tuberculosis infection and that this is a significant reservoir for future tuberculosis cases. Most cases occur within two years following initial infection. The identification of individuals with latent tuberculosis infection is difficult due to the lack of an ideal diagnostic assay and incomplete understanding of latent infection. Currently, there are three tests: the oldest tuberculin skin test, T-SPOT.TB and the latest QuantiFERON-Plus for the detection of Mycobacterium tuberculosis infection. The interpretation of the test results must be used in the conjunction with a patient’s epidemiological history, risk assessment, current clinical status, radiography and microbiological methods to ensure accurate diagnosis.

Key words

  • interferon-gamma release assays
  • latent tuberculosis infection
  • tuberculin skin test
  • tuberculosis
Open Access

Application of Metagenomic Analyses in Dentistry as a Novel Strategy Enabling Complex Insight into Microbial Diversity of the Oral Cavity

Published Online: 30 Mar 2017
Page range: 9 - 15

Abstract

Abstract

The composition of the oral microbiome in healthy individuals is complex and dynamic, and depends on many factors, such as anatomical location in the oral cavity, diet, oral hygiene habits or host immune responses. It is estimated at present that worldwide about 2 billion people suffer from diseases of the oral cavity, mainly periodontal disease and dental caries. Importantly, the oral microflora involved in local infections may spread and cause systemic, even life-threatening infections. In search for etiological agents of infections in dentistry, traditional approaches are not sufficient, as about 50% of oral bacteria are not cultivable. Instead, metagenomic analyses are particularly useful for studies of the complex oral microbiome – both in healthy individuals, and in patients with oral and dental diseases. In this paper we review the current and future applications of metagenomic studies in evaluation of both the composition of the oral microbiome as well as its potential pathogenic role in infections in dentistry.

Key words

  • dental caries
  • endodontics
  • metagenomics
  • periapical abscess
  • periodontitis
Open Access

Deletion of atoR from Streptococcus pyogenes Results in Hypervirulence in a Mouse Model of Sepsis and is LuxS Independent

Published Online: 30 Mar 2017
Page range: 17 - 24

Abstract

Abstract

Group A Streptococcus (GAS) is a Gram-positive human pathogen that causes a variety of diseases ranging from pharyngitis to life-threatening streptococcal toxic shock syndrome. Recently, several global gene expression analyses have yielded extensive new information regarding the regulation of genes encoding known and putative virulence factors in GAS. A microarray analysis found that transcription of the GAS gene M5005_Spy_1343 was significantly increased in response to interaction with human polymorphonuclear leukocytes. M5005_Spy_1343 is predicted to encode a member of the LysR family of transcriptional regulators and is located upstream of a putative operon containing six genes. Five of these genes have sequence similarity to genes involved in short-chain fatty acid metabolism, whereas the sixth gene (luxS) is found in many bacterial species and is involved in quorum sensing. Unexpectedly, inactivation of the M5005_Spy_1343 gene resulted in hypervirulence in an intraperitoneal mouse model of infection. Increased virulence was not due to changes in luxS gene expression. We postulate that short-chain fatty acid metabolism is involved in GAS pathogenesis.

Key words

  • host-pathogen interactions
  • short chain fatty acid synthesis
  • virulence factors
Open Access

Expression of the Fluoroquinolones Efflux Pump Genes acrA and mdfA in Urinary Escherichia coli Isolates

Published Online: 30 Mar 2017
Page range: 25 - 30

Abstract

Abstract

Escherichia coli is one of the most frequent causes of urinary tract infections. Efflux system overexpression is reported to contribute to E. coli resistance to several antibiotics. Our aim in this study was to investigate the relation between antibiotic resistance and the expression of the efflux pump genes acrA and mdfA in E. coli by real-time reverse transcription-PCR. We tested the in vitro susceptibilities to 12 antibiotics in 28 clinical isolates of E. coli obtained from urine samples. We also determined the minimum inhibitory concentrations of levofloxacin to these samples. We then revealed significant correlations between the overexpression of both mdfA and acrA and MICs of levofloxacin. In conclusion, we demonstrated that the increased expression of efflux pump genes such as mdfA and acrA can lead to levofloxacin resistance in E. coli. These findings contribute to further understanding of the molecular mechanisms of efflux pump systems and how they contribute to antibiotic resistance.

Keywords

  • A and A genes
  • efflux pump
  • levofloxacin
  • overexpression
Open Access

Antimicrobial Effects of Platelet-rich Plasma against Selected Oral and Periodontal Pathogens

Published Online: 30 Mar 2017
Page range: 31 - 37

Abstract

Abstract

Antimicrobial properties of platelet rich plasma (PRP) against various microorganisms have been recently pointed out. PRP could be an alternative to conventional antibiotics in preventing oral and periodontal infections. We examined whether PRP has in vitro antimicrobial properties against Aggregatibacter actinomycetemcomitans, Prophyromonas gingivalis, Staphylococcus aureus and Candida albicans. PRP and platelet-poor plasma (PPP) were obtained from whole blood of 10 healthy volunteers and 10 periodontitis patients. In vitro laboratory susceptibility was carried out using the modified agar diffusion method by measuring the diameters of inhibition zones on agar plates coated with selected microbial strains. Both calcium chloride (CaCl2) activated and non activated samples were tested. Both activated PRP and PPP, of both patients and controls, effectively inhibited the growth of A. actinomycetemcomitans, P. gingivalis and C. albicans. However, a statistically significant difference in favor of PRP was found indicating more susceptibility to PRP than PPP (p < 0.05). Non activated PRP and PPP exhibited negative zones of inhibition against the studied microorganisms. There was no activity against S. aureus. No statistically significant difference was found between the antimicrobial effects of PRP and/or PPP obtained from patients and controls (p > 0.05). We conclude that PRP is a potentially useful substance against oral and periodontal pathogens. Activated PRP was found to be more active than activated PPP and the activation of coagulation is a fundamental step. Additionally, the antimicrobial activity of PRP and/or PPP seems not to be affected by periodontitis.

Keywords

  • antimicrobial activity
  • oral infection
  • platelet-rich plasma
Open Access

A Comparative Study: Taxonomic Grouping of Alkaline Protease Producing Bacilli

Published Online: 30 Mar 2017
Page range: 39 - 56

Abstract

Abstract

Alkaline proteases have biotechnological importance due to their activity and stability at alkaline pH. 56 bacteria, capable of growing under alkaline conditions were isolated and their alkaline protease activities were carried out at different parameters to determine their optimum alkaline protease production conditions. Seven isolates were showed higher alkaline protease production capacity than the reference strains. The highest alkaline protease producing isolates (103125 U/g), E114 and C265, were identified as Bacillus licheniformis with 99.4% and Bacillus mojavensis 99.8% based on 16S rRNA gene sequence similarities, respectively. Interestingly, the isolates identified as Bacillus safensis were also found to be high alkaline protease producing strains. Genotypic characterizations of the isolates were also determined by using a wide range of molecular techniques (ARDRA, ITS-PCR, (GTG)5-PCR, BOX-PCR). These different techniques allowed us to differentiate the alkaliphilic isolates and the results were in concurrence with phylogenetic analyses of the 16S rRNA genes. While ITS-PCR provided the highest correlation with 16S rRNA groups, (GTG)5-PCR showed the highest differentiation at species and intra-species level. In this study, each of the biotechnologically valuable alkaline protease producing isolates was grouped into their taxonomic positions with multi-genotypic analyses.

Keywords

  • 16S rRNA gene sequence
  • alkaline protease
  • alkaliphilic
  • ARDRA
  • ITS-PCR
  • -PCR
Open Access

Isolation and Characterization of Phosphate-Solubilizing Bacteria from Mushroom Residues and their Effect on Tomato Plant Growth Promotion

Published Online: 30 Mar 2017
Page range: 57 - 65

Abstract

Abstract

Phosphorus is a major essential macronutrient for plant growth, and most of the phosphorus in soil remains in insoluble form. Highly efficient phosphate-solubilizing bacteria can be used to increase phosphorus in the plant rhizosphere. In this study, 13 isolates were obtained from waste mushroom residues, which were composed of cotton seed hulls, corn cob, biogas residues, and wood flour. NBRIP solid medium was used for isolation according to the dissolved phosphorus halo. Eight isolates produced indole acetic acid (61.5%), and six isolates produced siderophores (46.2%). Three highest phosphate-dissolving bacterial isolates, namely, M01, M04, and M11, were evaluated for their beneficial effects on the early growth of tomato plants (Solanum lycopersicum L. Wanza 15). Strains M01, M04, and M11 significantly increased the shoot dry weight by 30.5%, 32.6%, and 26.2%, and root dry weight by 27.1%, 33.1%, and 25.6%, respectively. Based on 16S rRNA gene sequence comparisons and phylogenetic positions, strains M01 and M04 belonged to the genus Acinetobacter, and strain M11 belonged to the genus Ochrobactrum. The findings suggest that waste mushroom residues are a potential resource of plant growth-promoting bacteria exhibiting satisfactory phosphate-solubilizing for sustainable agriculture.

Key words

  • 16S rRNA
  • mushroom residues
  • phosphate solubilizing bacteria
  • tomato plant growth
Open Access

Dipicolinic Acid Release and the Germination of Alicyclobacillus acidoterrestris Spores under Nutrient Germinants

Published Online: 30 Mar 2017
Page range: 67 - 74

Abstract

Abstract

The presence of Alicyclobacillus, a thermoacidophilic and spore-forming bacterium, in acidic fruit juices poses a serious problem for the processing industry. A typical sign of spoilage in contaminated juices is a characteristic phenolic off-flavour associated with the production of guaiacol. Spores are formed in response to starvation and in a natural environment re-access the nutrients, e.g.: L-alanine and AGFK – a mixture of asparagine, glucose, fructose and potassium, triggers germination. The aim of this study was to estimate the impact of L-alanine and AGFK on the germination of the spores of two Alicyclobacillus acidoterrestris strains and to evaluate the relationship of the germination rate with dipicolinic acid (DPA) release. The spores were suspended in apple juice or in buffers at pH 4 and pH 7, followed by the addition of L-alanine and AGFK. Suspensions were or were not subjected, to a temperature of 80°C/10 min and incubated for various periods of time at 45°C. Optical density (OD660) was used to estimate the number of germinated spores. The amount of DPA released was determined using HPLC. The results indicate that the degree of germination of A. acidoterrestris spores depended on the strain and time of incubation and the nutritious compounds used. The data obtained show that the amount of DPA released correlated to the number of A. acidoterrestris spores germinated.

Key words

  • AGFK mixture
  • dipicolinic acid
  • L-alanine
  • spore germination
Open Access

Microbial Biomass and Enzymatic Activity of the Surface Microlayer and Subsurface Water in Two Dystrophic Lakes

Published Online: 30 Mar 2017
Page range: 75 - 84

Abstract

Abstract

Nutrient and organic matter concentration, microbial biomass and activities were studied at the surface microlayers (SML) and subsurface waters (SSW) in two small forest lakes of different water colour. The SML in polyhumic lake is more enriched with dissolved inorganic nitrogen (0.141 mg l–1) than that of oligohumic lake (0.124 mg l–1), the former also contains higher levels of total nitrogen (2.66 mg l–1). Higher activities of lipase (Vmax 2290 nmol l–1 h–1 in oligo- and 6098 in polyhumic) and glucosidase (Vmax 41 nmol l–1 h–1 in oligo- and 49 in polyhumic) were in the SMLs in both lakes. Phosphatase activity was higher in the oligohumic SML than in SSW (Vmax 632 vs. 339 nmol l–1 h–1) while in polyhumic lake was higher in SSW (Vmax 2258 nmol l–1 h–1 vs. 1908 nmol l–1 h–1). Aminopeptidase activity in the SSW in both lakes was higher than in SMLs (Vmax 2117 in oligo- and 1213 nmol l–1 h–1 in polyhumic). It seems that solar radiation does inhibit neuston microbial community as a whole because secondary production and the share of active bacteria in total bacteria number were higher in SSW. However, in the oligohumic lake the abundance of bacteria in the SML was always higher than in the SSW (4.07 vs. 2.69 × 106 cells ml–1) while in the polyhumic lake was roughly equal (4.48 vs. 4.33 × 106 cells ml–1) in both layers. Results may also suggest that surface communities are not supplemented by immigration from bulk communities. The SML of humic lakes may act as important sinks for allochthonous nutrient resources and may then generate considerable energy pools for microbial food webs.

Key words

  • dystrophic lakes
  • enzymatic activity in lakes
  • neuston
  • bacteria in surface microlayer
Open Access

Suppressive Effect of Trichoderma spp. on toxigenic Fusarium species

Published Online: 30 Mar 2017
Page range: 85 - 100

Abstract

Abstract

The aim of the present study was to examine the abilities of twenty-four isolates belonging to ten different Trichoderma species (i.e., Trichoderma atroviride, Trichoderma citrinoviride, Trichoderma cremeum, Trichoderma hamatum, Trichoderma harzianum, Trichoderma koningiopsis, Trichoderma longibrachiatum, Trichoderma longipile, Trichoderma viride and Trichoderma viridescens) to inhibit the mycelial growth and mycotoxin production by five Fusarium strains (i.e., Fusarium avenaceum, Fusarium cerealis, Fusarium culmorum, Fusarium graminearum and Fusarium temperatum). Dual-culture bioassay on potato dextrose agar (PDA) medium clearly documented that all of the Trichoderma strains used in the study were capable of influencing the mycelial growth of at least four of all five Fusarium species on the fourth day after co-inoculation, when there was the first apparent physical contact between antagonist and pathogen. The qualitative evaluation of the interaction between the colonies after 14 days of co-culturing on PDA medium showed that ten Trichoderma strains completely overgrew and sporulated on the colony at least one of the tested Fusarium species. Whereas, the microscopic assay provided evidence that only T. atroviride AN240 and T. viride AN255 formed dense coils around the hyphae of the pathogen from where penetration took place. Of all screened Trichoderma strains, T. atroviride AN240 was also found to be the most efficient (69–100% toxin reduction) suppressors of mycotoxins (deoxynivalenol, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, nivalenol, zearalenone, beauvericin, moniliformin) production by all five Fusarium species on solid substrates. This research suggests that T. atroviride AN240 can be a promising candidate for the biological control of toxigenic Fusarium species.

Keywords

  • antagonism
  • dual culture bioassays
  • fungal interactions
  • microscopic observations
  • mycotoxins
Open Access

Screening and Identification of Yeasts Antagonistic to Pathogenic Fungi Show a Narrow Optimal pH Range for Antagonistic Activity

Published Online: 30 Mar 2017
Page range: 101 - 106

Abstract

Abstract

Microbes have evolved ways of interference competition to gain advantage over their ecological competitors. The use of secreted antagonistic compounds by yeast cells is one of the prominent examples. Although this killer behavior has been thoroughly studied in laboratory yeast strains, our knowledge of the antagonistic specificity of killer effects in nature remains limited. In this study, yeast strains were collected from various niches and screened for antagonistic activity against one toxin-sensitive strain of Saccharomyces cerevisiae and three pathogenic fungi. We demonstrate that some strains with antagonistic activity against these pathogenic fungi can be found in antagonist culture tests. These yeasts were identified as members of Trichosporon asahii, Candida stellimalicola, Wickerhamomyces anomalus, Ustilago esculenta, Aureobasidium pullulans, and Pichia kluyveri. The results indicated that the antagonistic activity of these killer yeasts has a narrow optimal pH range. Furthermore, we found that the antagonistic activity of some species is strain-dependent.

Keywords

  • antagonistic yeasts
  • interference competition
  • pathogenic fungi
Open Access

Use of Amplification Fragment Length Polymorphism to Genotype Pseudomonas stutzeri Strains Following Exposure to Ultraviolet Light A

Published Online: 30 Mar 2017
Page range: 107 - 111

Abstract

Abstract

Changes in ultraviolet light radiation can act as a selective force on the genetic and physiological traits of a microbial community. Two strains of the common soil bacterium Pseudomonas stutzeri, isolated from aquifer cores and from human spinal fluid were exposed to ultraviolet light. Amplification length polymorphism analysis (AFLP) was used to genotype this bacterial species and evaluate the effect of UVA-exposure on genomic DNA extracted from 18 survival colonies of the two strains compared to unexposed controls. AFLP showed a high discriminatory power, confirming the existence of different genotypes within the species and presence of DNA polymorphisms in UVA-exposed colonies.

Keywords

  • AFLP
  • polymorphisms
  • UVA exposure
Open Access

Vital Staining of Bacteria by Sunset Yellow Pigment

Published Online: 30 Mar 2017
Page range: 113 - 117

Abstract

Abstract

In this study, we describe a method for discriminating pathogenic bacteria with a dye. First, we determined that among several colours tested, the sunset yellow pigment easily coloured Escherichia coli bacteria yellow. Next, we demonstrated that E. coli O157:H7, Shigella flexneri O301, Staphylococcus aureus and Bacillus subtilis could all be well marked by sunset yellow pigment. Finally, we performed bacterial viability assays and found there was no effect on bacterial growth when in co-culture with sunset yellow. Our results suggest that sunset yellow is suitable pigment to dye microorganisms.

Keywords

  • bio-safety
  • pathogenic bacteria detection
  • sunset yellow
  • vital staining
Open Access

Outpatient Antibiotic Consumption Fluctuations in a View of Unreasonable Antibacterial Therapy

Published Online: 30 Mar 2017
Page range: 119 - 123

Abstract

Abstract

Unreasonable antibacterial therapy is suspected to be the main reason of emergence of multi-resistant bacteria. The connection between seasonal variability of antibiotic use and reasonable antibacterial therapy has been described. We examined the issue basing on the data obtained from the primary care system in Szczecin (Poland) in order to verify the situation in this region of Central Europe. Increase in antibiotic consumption in a viral infection season was proved to be statistically significant. Statistically significant differences in various drug forms dispensation were also observed. Increased consumption of antibiotics in seasons of influenza-like illnesses might be connected with a lack of proper diagnostics or numerous cases of bacterial co-infections.

Keywords

  • antibacterial agents
  • drug resistance
  • drug usage fluctuations
  • outpatient infection treatment
  • unreasonable antibacterial therapy
Open Access

Susceptibility of Vascular Implants to Colonization in vitro by Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Pseudomonas aeruginosa

Published Online: 30 Mar 2017
Page range: 125 - 129

Abstract

Abstract

We compared association of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Enterococcus faecalis with nine vascular implants after co-culture. Vascular implants were composed of various materials such as warp knitted polyester (with or without gelatin and silver ions), expanded polytetrafluoroethylene and biological materials – surface treated porcine pericardial patch and Omniflow II. The lowest overall number of associated bacteria was detected for polytetrafluoroethylene implants and porcine pericardial patch. The highest overall number of associated bacteria was detected for Omniflow II implant. The major source of variation, i.e. primary factor influencing colonization, is the implant type (56.22%), bacterial species is responsible for only 1.81%, and interaction of those two factors – 13.09% of variation.

Keywords

  • biofilm
  • graft infection
  • Omniflow II
  • porcine pericardial patch
  • vascular implant
Open Access

Antiviral Resistance of Splenocytes in Aged Mice

Published Online: 30 Mar 2017
Page range: 131 - 134

Abstract

Abstract

We compared the susceptibility to viral infection of splenocytes, isolated from young versus old CBA mice, and evaluated the antiviral actions of lactoferrin in splenocytes infected with Encephalomyocarditis virus (EMCV). Recombinant mouse lactoferrin (rmLF) and bovine lactoferrin (bLF) were used. There were no differences in the susceptibility to EMCV infection in the studied age categories. Both types of lactoferrins were protective in young and old mice. The study confirmed the undisturbed viral resistance in old mice and the protective actions of lactoferrin in viral infection. The antiviral action of the homologous mouse lactoferrin was demonstrated for the first time.

Keywords

  • immune ageing
  • lactoferrin
  • mice
  • splenocytes
  • viral resistance
32 Articles
Open Access

From Latent Tuberculosis Infection to Tuberculosis. News in Diagnostics (QuantiFERON-Plus)

Published Online: 30 Mar 2017
Page range: 5 - 8

Abstract

Abstract

It is estimated that one third of the world’s population have latent tuberculosis infection and that this is a significant reservoir for future tuberculosis cases. Most cases occur within two years following initial infection. The identification of individuals with latent tuberculosis infection is difficult due to the lack of an ideal diagnostic assay and incomplete understanding of latent infection. Currently, there are three tests: the oldest tuberculin skin test, T-SPOT.TB and the latest QuantiFERON-Plus for the detection of Mycobacterium tuberculosis infection. The interpretation of the test results must be used in the conjunction with a patient’s epidemiological history, risk assessment, current clinical status, radiography and microbiological methods to ensure accurate diagnosis.

Key words

  • interferon-gamma release assays
  • latent tuberculosis infection
  • tuberculin skin test
  • tuberculosis
Open Access

Application of Metagenomic Analyses in Dentistry as a Novel Strategy Enabling Complex Insight into Microbial Diversity of the Oral Cavity

Published Online: 30 Mar 2017
Page range: 9 - 15

Abstract

Abstract

The composition of the oral microbiome in healthy individuals is complex and dynamic, and depends on many factors, such as anatomical location in the oral cavity, diet, oral hygiene habits or host immune responses. It is estimated at present that worldwide about 2 billion people suffer from diseases of the oral cavity, mainly periodontal disease and dental caries. Importantly, the oral microflora involved in local infections may spread and cause systemic, even life-threatening infections. In search for etiological agents of infections in dentistry, traditional approaches are not sufficient, as about 50% of oral bacteria are not cultivable. Instead, metagenomic analyses are particularly useful for studies of the complex oral microbiome – both in healthy individuals, and in patients with oral and dental diseases. In this paper we review the current and future applications of metagenomic studies in evaluation of both the composition of the oral microbiome as well as its potential pathogenic role in infections in dentistry.

Key words

  • dental caries
  • endodontics
  • metagenomics
  • periapical abscess
  • periodontitis
Open Access

Deletion of atoR from Streptococcus pyogenes Results in Hypervirulence in a Mouse Model of Sepsis and is LuxS Independent

Published Online: 30 Mar 2017
Page range: 17 - 24

Abstract

Abstract

Group A Streptococcus (GAS) is a Gram-positive human pathogen that causes a variety of diseases ranging from pharyngitis to life-threatening streptococcal toxic shock syndrome. Recently, several global gene expression analyses have yielded extensive new information regarding the regulation of genes encoding known and putative virulence factors in GAS. A microarray analysis found that transcription of the GAS gene M5005_Spy_1343 was significantly increased in response to interaction with human polymorphonuclear leukocytes. M5005_Spy_1343 is predicted to encode a member of the LysR family of transcriptional regulators and is located upstream of a putative operon containing six genes. Five of these genes have sequence similarity to genes involved in short-chain fatty acid metabolism, whereas the sixth gene (luxS) is found in many bacterial species and is involved in quorum sensing. Unexpectedly, inactivation of the M5005_Spy_1343 gene resulted in hypervirulence in an intraperitoneal mouse model of infection. Increased virulence was not due to changes in luxS gene expression. We postulate that short-chain fatty acid metabolism is involved in GAS pathogenesis.

Key words

  • host-pathogen interactions
  • short chain fatty acid synthesis
  • virulence factors
Open Access

Expression of the Fluoroquinolones Efflux Pump Genes acrA and mdfA in Urinary Escherichia coli Isolates

Published Online: 30 Mar 2017
Page range: 25 - 30

Abstract

Abstract

Escherichia coli is one of the most frequent causes of urinary tract infections. Efflux system overexpression is reported to contribute to E. coli resistance to several antibiotics. Our aim in this study was to investigate the relation between antibiotic resistance and the expression of the efflux pump genes acrA and mdfA in E. coli by real-time reverse transcription-PCR. We tested the in vitro susceptibilities to 12 antibiotics in 28 clinical isolates of E. coli obtained from urine samples. We also determined the minimum inhibitory concentrations of levofloxacin to these samples. We then revealed significant correlations between the overexpression of both mdfA and acrA and MICs of levofloxacin. In conclusion, we demonstrated that the increased expression of efflux pump genes such as mdfA and acrA can lead to levofloxacin resistance in E. coli. These findings contribute to further understanding of the molecular mechanisms of efflux pump systems and how they contribute to antibiotic resistance.

Keywords

  • A and A genes
  • efflux pump
  • levofloxacin
  • overexpression
Open Access

Antimicrobial Effects of Platelet-rich Plasma against Selected Oral and Periodontal Pathogens

Published Online: 30 Mar 2017
Page range: 31 - 37

Abstract

Abstract

Antimicrobial properties of platelet rich plasma (PRP) against various microorganisms have been recently pointed out. PRP could be an alternative to conventional antibiotics in preventing oral and periodontal infections. We examined whether PRP has in vitro antimicrobial properties against Aggregatibacter actinomycetemcomitans, Prophyromonas gingivalis, Staphylococcus aureus and Candida albicans. PRP and platelet-poor plasma (PPP) were obtained from whole blood of 10 healthy volunteers and 10 periodontitis patients. In vitro laboratory susceptibility was carried out using the modified agar diffusion method by measuring the diameters of inhibition zones on agar plates coated with selected microbial strains. Both calcium chloride (CaCl2) activated and non activated samples were tested. Both activated PRP and PPP, of both patients and controls, effectively inhibited the growth of A. actinomycetemcomitans, P. gingivalis and C. albicans. However, a statistically significant difference in favor of PRP was found indicating more susceptibility to PRP than PPP (p < 0.05). Non activated PRP and PPP exhibited negative zones of inhibition against the studied microorganisms. There was no activity against S. aureus. No statistically significant difference was found between the antimicrobial effects of PRP and/or PPP obtained from patients and controls (p > 0.05). We conclude that PRP is a potentially useful substance against oral and periodontal pathogens. Activated PRP was found to be more active than activated PPP and the activation of coagulation is a fundamental step. Additionally, the antimicrobial activity of PRP and/or PPP seems not to be affected by periodontitis.

Keywords

  • antimicrobial activity
  • oral infection
  • platelet-rich plasma
Open Access

A Comparative Study: Taxonomic Grouping of Alkaline Protease Producing Bacilli

Published Online: 30 Mar 2017
Page range: 39 - 56

Abstract

Abstract

Alkaline proteases have biotechnological importance due to their activity and stability at alkaline pH. 56 bacteria, capable of growing under alkaline conditions were isolated and their alkaline protease activities were carried out at different parameters to determine their optimum alkaline protease production conditions. Seven isolates were showed higher alkaline protease production capacity than the reference strains. The highest alkaline protease producing isolates (103125 U/g), E114 and C265, were identified as Bacillus licheniformis with 99.4% and Bacillus mojavensis 99.8% based on 16S rRNA gene sequence similarities, respectively. Interestingly, the isolates identified as Bacillus safensis were also found to be high alkaline protease producing strains. Genotypic characterizations of the isolates were also determined by using a wide range of molecular techniques (ARDRA, ITS-PCR, (GTG)5-PCR, BOX-PCR). These different techniques allowed us to differentiate the alkaliphilic isolates and the results were in concurrence with phylogenetic analyses of the 16S rRNA genes. While ITS-PCR provided the highest correlation with 16S rRNA groups, (GTG)5-PCR showed the highest differentiation at species and intra-species level. In this study, each of the biotechnologically valuable alkaline protease producing isolates was grouped into their taxonomic positions with multi-genotypic analyses.

Keywords

  • 16S rRNA gene sequence
  • alkaline protease
  • alkaliphilic
  • ARDRA
  • ITS-PCR
  • -PCR
Open Access

Isolation and Characterization of Phosphate-Solubilizing Bacteria from Mushroom Residues and their Effect on Tomato Plant Growth Promotion

Published Online: 30 Mar 2017
Page range: 57 - 65

Abstract

Abstract

Phosphorus is a major essential macronutrient for plant growth, and most of the phosphorus in soil remains in insoluble form. Highly efficient phosphate-solubilizing bacteria can be used to increase phosphorus in the plant rhizosphere. In this study, 13 isolates were obtained from waste mushroom residues, which were composed of cotton seed hulls, corn cob, biogas residues, and wood flour. NBRIP solid medium was used for isolation according to the dissolved phosphorus halo. Eight isolates produced indole acetic acid (61.5%), and six isolates produced siderophores (46.2%). Three highest phosphate-dissolving bacterial isolates, namely, M01, M04, and M11, were evaluated for their beneficial effects on the early growth of tomato plants (Solanum lycopersicum L. Wanza 15). Strains M01, M04, and M11 significantly increased the shoot dry weight by 30.5%, 32.6%, and 26.2%, and root dry weight by 27.1%, 33.1%, and 25.6%, respectively. Based on 16S rRNA gene sequence comparisons and phylogenetic positions, strains M01 and M04 belonged to the genus Acinetobacter, and strain M11 belonged to the genus Ochrobactrum. The findings suggest that waste mushroom residues are a potential resource of plant growth-promoting bacteria exhibiting satisfactory phosphate-solubilizing for sustainable agriculture.

Key words

  • 16S rRNA
  • mushroom residues
  • phosphate solubilizing bacteria
  • tomato plant growth
Open Access

Dipicolinic Acid Release and the Germination of Alicyclobacillus acidoterrestris Spores under Nutrient Germinants

Published Online: 30 Mar 2017
Page range: 67 - 74

Abstract

Abstract

The presence of Alicyclobacillus, a thermoacidophilic and spore-forming bacterium, in acidic fruit juices poses a serious problem for the processing industry. A typical sign of spoilage in contaminated juices is a characteristic phenolic off-flavour associated with the production of guaiacol. Spores are formed in response to starvation and in a natural environment re-access the nutrients, e.g.: L-alanine and AGFK – a mixture of asparagine, glucose, fructose and potassium, triggers germination. The aim of this study was to estimate the impact of L-alanine and AGFK on the germination of the spores of two Alicyclobacillus acidoterrestris strains and to evaluate the relationship of the germination rate with dipicolinic acid (DPA) release. The spores were suspended in apple juice or in buffers at pH 4 and pH 7, followed by the addition of L-alanine and AGFK. Suspensions were or were not subjected, to a temperature of 80°C/10 min and incubated for various periods of time at 45°C. Optical density (OD660) was used to estimate the number of germinated spores. The amount of DPA released was determined using HPLC. The results indicate that the degree of germination of A. acidoterrestris spores depended on the strain and time of incubation and the nutritious compounds used. The data obtained show that the amount of DPA released correlated to the number of A. acidoterrestris spores germinated.

Key words

  • AGFK mixture
  • dipicolinic acid
  • L-alanine
  • spore germination
Open Access

Microbial Biomass and Enzymatic Activity of the Surface Microlayer and Subsurface Water in Two Dystrophic Lakes

Published Online: 30 Mar 2017
Page range: 75 - 84

Abstract

Abstract

Nutrient and organic matter concentration, microbial biomass and activities were studied at the surface microlayers (SML) and subsurface waters (SSW) in two small forest lakes of different water colour. The SML in polyhumic lake is more enriched with dissolved inorganic nitrogen (0.141 mg l–1) than that of oligohumic lake (0.124 mg l–1), the former also contains higher levels of total nitrogen (2.66 mg l–1). Higher activities of lipase (Vmax 2290 nmol l–1 h–1 in oligo- and 6098 in polyhumic) and glucosidase (Vmax 41 nmol l–1 h–1 in oligo- and 49 in polyhumic) were in the SMLs in both lakes. Phosphatase activity was higher in the oligohumic SML than in SSW (Vmax 632 vs. 339 nmol l–1 h–1) while in polyhumic lake was higher in SSW (Vmax 2258 nmol l–1 h–1 vs. 1908 nmol l–1 h–1). Aminopeptidase activity in the SSW in both lakes was higher than in SMLs (Vmax 2117 in oligo- and 1213 nmol l–1 h–1 in polyhumic). It seems that solar radiation does inhibit neuston microbial community as a whole because secondary production and the share of active bacteria in total bacteria number were higher in SSW. However, in the oligohumic lake the abundance of bacteria in the SML was always higher than in the SSW (4.07 vs. 2.69 × 106 cells ml–1) while in the polyhumic lake was roughly equal (4.48 vs. 4.33 × 106 cells ml–1) in both layers. Results may also suggest that surface communities are not supplemented by immigration from bulk communities. The SML of humic lakes may act as important sinks for allochthonous nutrient resources and may then generate considerable energy pools for microbial food webs.

Key words

  • dystrophic lakes
  • enzymatic activity in lakes
  • neuston
  • bacteria in surface microlayer
Open Access

Suppressive Effect of Trichoderma spp. on toxigenic Fusarium species

Published Online: 30 Mar 2017
Page range: 85 - 100

Abstract

Abstract

The aim of the present study was to examine the abilities of twenty-four isolates belonging to ten different Trichoderma species (i.e., Trichoderma atroviride, Trichoderma citrinoviride, Trichoderma cremeum, Trichoderma hamatum, Trichoderma harzianum, Trichoderma koningiopsis, Trichoderma longibrachiatum, Trichoderma longipile, Trichoderma viride and Trichoderma viridescens) to inhibit the mycelial growth and mycotoxin production by five Fusarium strains (i.e., Fusarium avenaceum, Fusarium cerealis, Fusarium culmorum, Fusarium graminearum and Fusarium temperatum). Dual-culture bioassay on potato dextrose agar (PDA) medium clearly documented that all of the Trichoderma strains used in the study were capable of influencing the mycelial growth of at least four of all five Fusarium species on the fourth day after co-inoculation, when there was the first apparent physical contact between antagonist and pathogen. The qualitative evaluation of the interaction between the colonies after 14 days of co-culturing on PDA medium showed that ten Trichoderma strains completely overgrew and sporulated on the colony at least one of the tested Fusarium species. Whereas, the microscopic assay provided evidence that only T. atroviride AN240 and T. viride AN255 formed dense coils around the hyphae of the pathogen from where penetration took place. Of all screened Trichoderma strains, T. atroviride AN240 was also found to be the most efficient (69–100% toxin reduction) suppressors of mycotoxins (deoxynivalenol, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, nivalenol, zearalenone, beauvericin, moniliformin) production by all five Fusarium species on solid substrates. This research suggests that T. atroviride AN240 can be a promising candidate for the biological control of toxigenic Fusarium species.

Keywords

  • antagonism
  • dual culture bioassays
  • fungal interactions
  • microscopic observations
  • mycotoxins
Open Access

Screening and Identification of Yeasts Antagonistic to Pathogenic Fungi Show a Narrow Optimal pH Range for Antagonistic Activity

Published Online: 30 Mar 2017
Page range: 101 - 106

Abstract

Abstract

Microbes have evolved ways of interference competition to gain advantage over their ecological competitors. The use of secreted antagonistic compounds by yeast cells is one of the prominent examples. Although this killer behavior has been thoroughly studied in laboratory yeast strains, our knowledge of the antagonistic specificity of killer effects in nature remains limited. In this study, yeast strains were collected from various niches and screened for antagonistic activity against one toxin-sensitive strain of Saccharomyces cerevisiae and three pathogenic fungi. We demonstrate that some strains with antagonistic activity against these pathogenic fungi can be found in antagonist culture tests. These yeasts were identified as members of Trichosporon asahii, Candida stellimalicola, Wickerhamomyces anomalus, Ustilago esculenta, Aureobasidium pullulans, and Pichia kluyveri. The results indicated that the antagonistic activity of these killer yeasts has a narrow optimal pH range. Furthermore, we found that the antagonistic activity of some species is strain-dependent.

Keywords

  • antagonistic yeasts
  • interference competition
  • pathogenic fungi
Open Access

Use of Amplification Fragment Length Polymorphism to Genotype Pseudomonas stutzeri Strains Following Exposure to Ultraviolet Light A

Published Online: 30 Mar 2017
Page range: 107 - 111

Abstract

Abstract

Changes in ultraviolet light radiation can act as a selective force on the genetic and physiological traits of a microbial community. Two strains of the common soil bacterium Pseudomonas stutzeri, isolated from aquifer cores and from human spinal fluid were exposed to ultraviolet light. Amplification length polymorphism analysis (AFLP) was used to genotype this bacterial species and evaluate the effect of UVA-exposure on genomic DNA extracted from 18 survival colonies of the two strains compared to unexposed controls. AFLP showed a high discriminatory power, confirming the existence of different genotypes within the species and presence of DNA polymorphisms in UVA-exposed colonies.

Keywords

  • AFLP
  • polymorphisms
  • UVA exposure
Open Access

Vital Staining of Bacteria by Sunset Yellow Pigment

Published Online: 30 Mar 2017
Page range: 113 - 117

Abstract

Abstract

In this study, we describe a method for discriminating pathogenic bacteria with a dye. First, we determined that among several colours tested, the sunset yellow pigment easily coloured Escherichia coli bacteria yellow. Next, we demonstrated that E. coli O157:H7, Shigella flexneri O301, Staphylococcus aureus and Bacillus subtilis could all be well marked by sunset yellow pigment. Finally, we performed bacterial viability assays and found there was no effect on bacterial growth when in co-culture with sunset yellow. Our results suggest that sunset yellow is suitable pigment to dye microorganisms.

Keywords

  • bio-safety
  • pathogenic bacteria detection
  • sunset yellow
  • vital staining
Open Access

Outpatient Antibiotic Consumption Fluctuations in a View of Unreasonable Antibacterial Therapy

Published Online: 30 Mar 2017
Page range: 119 - 123

Abstract

Abstract

Unreasonable antibacterial therapy is suspected to be the main reason of emergence of multi-resistant bacteria. The connection between seasonal variability of antibiotic use and reasonable antibacterial therapy has been described. We examined the issue basing on the data obtained from the primary care system in Szczecin (Poland) in order to verify the situation in this region of Central Europe. Increase in antibiotic consumption in a viral infection season was proved to be statistically significant. Statistically significant differences in various drug forms dispensation were also observed. Increased consumption of antibiotics in seasons of influenza-like illnesses might be connected with a lack of proper diagnostics or numerous cases of bacterial co-infections.

Keywords

  • antibacterial agents
  • drug resistance
  • drug usage fluctuations
  • outpatient infection treatment
  • unreasonable antibacterial therapy
Open Access

Susceptibility of Vascular Implants to Colonization in vitro by Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Pseudomonas aeruginosa

Published Online: 30 Mar 2017
Page range: 125 - 129

Abstract

Abstract

We compared association of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Enterococcus faecalis with nine vascular implants after co-culture. Vascular implants were composed of various materials such as warp knitted polyester (with or without gelatin and silver ions), expanded polytetrafluoroethylene and biological materials – surface treated porcine pericardial patch and Omniflow II. The lowest overall number of associated bacteria was detected for polytetrafluoroethylene implants and porcine pericardial patch. The highest overall number of associated bacteria was detected for Omniflow II implant. The major source of variation, i.e. primary factor influencing colonization, is the implant type (56.22%), bacterial species is responsible for only 1.81%, and interaction of those two factors – 13.09% of variation.

Keywords

  • biofilm
  • graft infection
  • Omniflow II
  • porcine pericardial patch
  • vascular implant
Open Access

Antiviral Resistance of Splenocytes in Aged Mice

Published Online: 30 Mar 2017
Page range: 131 - 134

Abstract

Abstract

We compared the susceptibility to viral infection of splenocytes, isolated from young versus old CBA mice, and evaluated the antiviral actions of lactoferrin in splenocytes infected with Encephalomyocarditis virus (EMCV). Recombinant mouse lactoferrin (rmLF) and bovine lactoferrin (bLF) were used. There were no differences in the susceptibility to EMCV infection in the studied age categories. Both types of lactoferrins were protective in young and old mice. The study confirmed the undisturbed viral resistance in old mice and the protective actions of lactoferrin in viral infection. The antiviral action of the homologous mouse lactoferrin was demonstrated for the first time.

Keywords

  • immune ageing
  • lactoferrin
  • mice
  • splenocytes
  • viral resistance

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