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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)

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

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

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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 4 (December 2017)

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

Search

32 Articles
access type Open Access

Transferrin and Lactoferrin – Human Iron Sources for Enterococci

Published Online: 04 Dec 2017
Page range: 419 - 426

Abstract

Abstract

To overcome limitations in iron acquisition, enterococci have evolved a number of mechanisms to scavenge iron from the host iron-binding proteins – transferrin (TR) and lactoferrin (LF). The aim of this study was to demonstrate the mechanisms by which enterococci utilize human TR and LF bound iron. The study included two strains of Enterococcus faecalis grown in iron-deficient and iron-excess media respectively. The binding activity of both proteins was monitored using proteins labelled with 125I. The uptake of iron by enterococci was determined using 59Fe labelled proteins. Reduction of iron bound to TR and LF was assayed with ferrozine. The proteolytic cleavage of TR and LF was visualized by SDS-polyacrylamide gel electrophoresis. The siderophore activity was measured with chrome azurol S. The study revealed that enterococci use several ways to acquire iron from TR and LF, such as iron chelating siderophores, iron reduction – facilitated iron release, protein degradation – promoted iron release, and receptor mediated capture of the iron-host protein complexes. The broad spectrum of iron acquisition mechanisms used by enterococci may play a significant role in the colonization of the human body and the resulting pathogenicity.

Keywords

  • spp
  • iron acquisition
  • lactoferrin
  • siderophores
  • transferrin
access type Open Access

The Prevalence of Exoenzyme S Gene in Multidrug-Sensitive and Multidrug-Resistant Pseudomonas aeruginosa Clinical Strains

Published Online: 04 Dec 2017
Page range: 427 - 432

Abstract

Abstract

Pseudomonas aeruginosa rods are one of the most commonly isolated microorganisms from clinical specimens, usually responsible for nosocomial infections. Antibiotic-resistant P. aeruginosa strains may present reduced expression of virulence factors. This fact may be caused by appropriate genome management to adapt to changing conditions of the hospital environment. Virulence factors genes may be replaced by those crucial to survive, like antimicrobial resistance genes. The aim of this study was to evaluate, using PCR, the occurrence of exoenzyme S-coding gene (exoS) in two distinct groups of P. aeruginosa strains: 83 multidrug-sensitive (MDS) and 65 multidrug-resistant (MDR) isolates. ExoS gene was noted in 72 (48.7%) of the examined strains: 44 (53.0%) MDS and 28 (43.1%) MDR. The observed differences were not statistically significant (p = 0.1505). P. aeruginosa strains virulence is rather determined by the expression regulation of the possessed genes than the difference in genes frequency amongst strains with different antimicrobial susceptibility patterns.

Keywords

  • exoenzyme S
  • multidrug sensitive
  • multidrug resistant
  • virulence genes
access type Open Access

Temperature, pH and Trimethoprim-Sulfamethoxazole Are Potent Inhibitors of Biofilm Formation by Stenotrophomonas maltophilia Clinical Isolates

Published Online: 04 Dec 2017
Page range: 433 - 438

Abstract

Abstract

Stenotrophomonas maltophilia, an opportunistic pathogen usually connected with healthcare-associated infections, is an environmental bacterium. Intrinsic resistance to multiple antibiotics, with different virulence determinants in the last decade classified this bacterium in the group of global multiple drug resistant (MDR) organism. S. maltophilia clinical isolates, were collected from tertiary care pediatric hospital in Belgrade, Serbia to investigate influence of different factors on biofilm formation, kinetics of biofilm formation for strong biofilm producers and effect of trimethoprim-sulfamethoxazole (TMP/SMX) on formed biofilm. Most of the isolates (89.8%) were able to form a biofilm. Analysis of biofilm formation in different growth conditions showed that changing of temeperature and pH had the stronggest effect on biofilm formation almost equally in group of cystic fibrosis (CF) and non-CF strains. TMP/SMX in concentration of 50 μg/ml reduced completely 24 h old biofilms while concentration of 25 μg/ml effects formed biofilms in a strain dependent manner. Among strains able to form strong biofilm CF isolates formed biofilm slower than non-CF isolates, while shaking conditions did not affect biofilm formation. Swimming motility was detected in both CF and non-CF isolates, however more motile strain formed stronger biofilms. This study suggests that temperature, pH and TMP/SMX had the strongest influence on biofilm formation in analyzed collection of S. maltophilia. A positive correlation between motility and strength of formed biofilm was demonstrated.

Keywords

  • biofilm
  • cystic fibrosis
  • opportunistic pathogen
  • trimethoprim-sulfamethoxazole
access type Open Access

Prevalence, Influencing Factors, Antibiotic Resistance, Toxin and Molecular Characteristics of Staphylococcus aureus and MRSA Nasal Carriage among Diabetic Population in the United States, 2001–2004

Published Online: 04 Dec 2017
Page range: 439 - 448

Abstract

Abstract

Diabetic population were reported more likely to suffer carriage and infection with Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA) than non-diabetic population. We aim to elucidate the prevalence and characteristics of S. aureus and MRSA nasal carriage among diabetic population in the United States National Health and Nutrition Examination Survey, 2001–2004. Univariate analyses were conducted using Chi-square test, Fisher’s exact probability test or student t test, as appropriate. Multivariate analysis using logistic regression was conducted to assess the association between influencing factors and S. aureus and MRSA nasal carriage. 1010 diabetic participants were included in the study. The prevalence of S. aureus and MRSA nasal carriage were 28.32% and 1.09%, respectively. After the logistic regression, ever had a painful sensation or tingling in hands or feet past three months (Odds Ratio [OR] = 0.359, 95% Confidence Interval [CI], 0.146–0.882) was significant among S. aureus nasal carriage and gender (OR = 3.410, 95% CI, 1.091–10.653) was significant among MRSA nasal carriage. The proportions of staphylococcal enterotoxin (SE) A, SEB, SEC, SED, Toxic-shock syndrome toxin-1, and Panton Valentine Leukocidin toxin among S. aureus strains were 18.75%, 3.13%, 12.50%, 15.63%, 28.13%, and 9.38%, respectively. 63.63% of MRSA strains were community-acquired, 27.27% were hospital-acquired, and 9.09% were non-typeable. Diabetic patients might be more likely to carry S. aureus and MRSA in the United States. Improving hand hygiene compliance, reducing antibiotic overuse, screening for carriers, and decolonization are recommended to reduce the spread of S. aureus and MRSA, especially in community.

Keywords

  • diabetics
  • MRSA
  • nasal carriage
  • NHANES
access type Open Access

Production, Characterization and Valuable Applications of Exopolysaccharides from Marine Bacillus subtilis SH1

Published Online: 04 Dec 2017
Page range: 449 - 462

Abstract

Abstract

Exopolysaccharides (EPSs) are high molecular weight polymers consisting of different sugar residues they are preferable for replacing synthetic polymers as they are degradable and nontoxic. Many microorganisms possess the ability to synthesize and excrete exopolysaccharides with novel chemical compositions, properties and structures to have potential applications in different fields. The present study attempt to optimize the production of EPS by marine Bacillus subtilis SH1 in addition to characterization and investigation of different valuable applications. Effect of medium type, incubation period and pH were studied using the one factor at a time experiments. It was shown that the highest productivity (24 gl–1) of exopolysaccharides was recorded by using yeast malt glucose medium with pH 9 at the fourth day of incubation. Experimental design using Response Surface Methodology (RSM) was applied to optimize various nutrients at different concentrations. The finalized optimized medium contained (gl–1) glucose (5), peptone (2.5), yeast extract (4.5) and malt extract (4.5) increased the production of EPS to 33.8 gl–1 with1.4 fold increase compared to the basal medium. Chemical characterization of the extracted EPS showed that, FTIR spectra exhibited bands at various regions. Moreover, HPLC chromatogram indicated that the EPS was a heteropolysaccharide consisting of maltose and rhamnose. The study was extended to evaluate the potentiality of the extracted polysaccharides in different medical applications. Results concluded that, EPS exhibited antibacterial activity against Aeromonas hydrophila, Pseudomonas aeruginosa and Streptococcus faecalis and the highest antibacterial activity (7.8, 9 and 10.4 AU/ml) was against S. faecalis at 50, 100 and 200 mg/ml respectively. The EPS exhibited various degree of antitumor effect toward the tested cell lines (MCF-7, HCT-116 and HepG2). In addition, EPS exhibited antiviral activity at 500 μg/ml. The antioxidant capacity increased with increasing the concentration of the sample. Scanning electron microscopic analysis showed that EPS had compact film-like structure, which could make it a useful in the future applications as in preparing plasticized film.

Keywords

  • SH1
  • anticancer
  • antiviral
  • exopolysaccharides
  • response surface methodology
access type Open Access

Characterisation of Antimicrobial Properties of Extracts of Selected Medicinal Plants

Published Online: 04 Dec 2017
Page range: 463 - 472

Abstract

Abstract

The scope of the experiments included analysis of the antimicrobial activity of ethanolic, methanolic and aqueous extracts against bacterial and fungal cultures and determination of the minimum inhibitory concentration of plant extracts tested microbial growth. Analysis of the antifungal and antibacterial activity was carried out by the disc diffusion method using paper discs. In the experiment 11 species of microorganisms – 8 bacterial and 3 fungal strains were used. The highest antimicrobial activity against the tested strains was demonstrated by black elder (Sambucus nigra L.), black locust (Robinia pseudoacacia L.) and lingonberry (Vaccinium vitis-idaea L.) extracts. The study showed the diverse morphological activity of specific parts of elderberry and quince, which is the effect of different polyphenolic profile of these plants. The yeast Saccharomyces cerevisiae, Escherichia coli, Pseudomonas putida and Bacillus subtilis showed the highest sensitivity to the effect of extracts of the analysed plants. As a positive control three antibiotics – amphotericin B, vancomycin and amoxicillin with clavulanic acid were used.

Keywords

  • L.
  • L.
  • L.
  • antimicrobial activity
  • medicinal plants
access type Open Access

Characterization of Bacteriocin-Producing Lactic Acid Bacteria Isolated from Native Fruits of Ecuadorian Amazon

Published Online: 04 Dec 2017
Page range: 473 - 481

Abstract

Abstract

Tropical, wild-type fruits are considered biodiverse “hotspots” of microorganisms with possible functional characteristics to be investigated. In this study, several native lactic acid bacteria (LAB) of Ecuadorian Amazon showing highly inhibitory potential were identified and characterized. Based on carbohydrate fermentation profile and 16S rRNA gene sequencing, seven strains were assigned as Lactobacillus plantarum and one strain as Weissella confusa. Using agar-well diffusion method the active synthetized components released in the neutralized and hydroxide peroxide eliminated cell-free supernatant were inhibited by proteolytic enzymes, while the activity was maintained stable after the treatment with catalase, lysozyme, α-amylase and lipase suggesting their proteinaceous nature. The inhibitory activity was stimulated by acidic conditions, upon exposure to high heat and maintained stable at different ranges of sodium chloride (4–10%). The DNA sequencing analysis confirmed the presence of plw structural gene encoding for plantacirin W in the selected L. plantarum strains. Moreover, we showed that the active peptides of Cys5-4 strains contrast effectively, in a bactericidal manner, the growth of food borne E. coli UTNEc1 and Salmonella UTNSm2, with about tree fold reduction of viable counts at the early stage of the target cell growth. The results indicated that the bacteriocin produced by selected native lactic acid bacteria strains has elevated capacity to suppress several pathogenic microorganisms implying their potential as antimicrobial agents or food preservatives.

Keywords

  • antimicrobial substances
  • bacteriocins
  • foodborne pathogens
  • lactic acid bacteria (LAB)
access type Open Access

Physiological Effects of Whey- and Milk-Based Probiotic Yogurt in Rats

Published Online: 04 Dec 2017
Page range: 483 - 490

Abstract

Abstract

In an in vitro experiment commercially available probiotic products were tested for the survival of bacteria under conditions of simulated human digestion either when used alone or mixed into yogurt. In the in vivo experiment the effects of feeding a whey- and milk-based yogurt prepared with the probiotic strain showing adequate survival in the in vitro experiment, was measured on body weight, feed consumption and immune response of rats (IgG and IgA level after immunisation), on the composition and volatile fatty acid production of the intestinal microbiota and on the structure of intestinal villi. The Lactobacillus acidophilus (LA-15) strain had inadequate surviving ability in rats. Bifidobacterium animalis ssp. lactis (BB-12) improved the composition of the intestinal microflora, whereas whey-containing product had a mild immunostimulating effect and exerted a favourable influence on the morphology of intestinal villi. The consumption of yogurts increased the depth of crypts in the ileum, which resulted in enhanced secretion and thus softer faeces.

Keywords

  • rat intestine physiology
  • physiological effect of whey and yogurt
access type Open Access

Identification of Lactobacillus delbrueckii and Streptococcus thermophilus Strains Present in Artisanal Raw Cow Milk Cheese Using Real-time PCR and Classic Plate Count Methods

Published Online: 04 Dec 2017
Page range: 491 - 499

Abstract

Abstract

The aim of this paper was to detect Lactobacillus delbrueckii and Streptococcus thermophilus using real-time quantitative PCR assay in 7-day ripening cheese produced from unpasteurised milk. Real-time quantitative PCR assays were designed to identify and enumerate the chosen species of lactic acid bacteria (LAB) in ripened cheese. The results of molecular quantification and classic bacterial enumeration showed a high level of similarity proving that DNA extraction was carried out in a proper way and that genomic DNA solutions were free of PCR inhibitors. These methods revealed the presence of L. delbrueckii and S. thermophilus. The real-time PCR enabled quantification with a detection of 101–103 CFU/g of product. qPCR-standard curves were linear over seven log units down to 101 copies per reaction; efficiencies ranged from 77.9% to 93.6%. Cheese samples were analysed with plate count method and qPCR in parallel. Compared with the classic plate count method, the newly developed qPCR method provided faster and species specific identification of two dairy LAB and yielded comparable quantitative results.

Keywords

  • artisanal cheese microflora
  • LAB identification
access type Open Access

The Determination and Correlation of Various Virulence Genes, ESBL, Serum Bactericidal Effect and Biofilm Formation of Clinical Isolated Classical Klebsiella pneumoniae and Hypervirulent Klebsiella pneumoniae from Respiratory Tract Infected Patients

Published Online: 04 Dec 2017
Page range: 501 - 508

Abstract

Abstract

Klebsiella pneumoniae strains that are commonly recognized by clinicians and microbiologists are termed as classical K. pneumoniae (cKP). A strain with capsule-associated mucopolysaccharide web is known as hypervirulent K. pneumoniae (hvKP) as it enhances the serum resistant and biofilm production. Aim is to determine and correlate various virulence genes, ESBL, serum bactericidal effect and biofilm formation of clinical isolated cKP and hvKP from respiratory tract infected patients. A total of 96 K. pneumoniae strains were isolated from sputum of respiratory tract infected patients. The isolates were performed string test, AST, ESBL virulence gene, serum bactericidal and biofilm assays. Out of 96 isolates, 39 isolates (40.6%) were identified with hypervirulent phenotypes. The number of cKP exhibiting resistance to the tested antimicrobials and ESBLs were significantly higher than that of the hvKP strains. The virulence genes of K. pneumoniae such as K1, K2, rmpA, uge, kfu and aerobactin were strongly associated with hvKP than cKP. However, no significant difference was found in FIM-1 and MrKD3 genes. ESBL producing cKP and hvKP were significantly associated with strong biofilm formation (both P < 0.05) and highly associated with bactericidal effect of serum (both P < 0.05) than cKP strains. However, neither biofilm formation nor bactericidal effect of serum was found with significant difference in between ESBL producing cKP and ESBL producing hvKP strains (both P > 0.05). Although the hvKP possess more virulence gene, but they didn’t show any significant difference between biofilm formation and bactericidal effect of serum compared with ESBL producing cKP strains.

Keywords

  • biofilm
  • ESBL
  • classical hypervirulent
  • serum resistance
  • virulence genes
access type Open Access

Characterization of Microbial Communities in Acidified, Sulfur Containing Soils

Published Online: 04 Dec 2017
Page range: 509 - 517

Abstract

Abstract

Over a period of three years, microbial communities in acidified soil with high sulfur content were analyzed. In soil water extracts ureolytic, proteolytic, oxidoreductive, and lipolytic activity were detected. The presented results indicate that the enzymatic activity of soil microbial communities varied considerably over time. Isolated 26 (80%) bacterial strains belonged to genus Bacillus sp. and were identified by cultivation and 16S rRNA methods. The commercially available procedures for bacterial DNA isolation from acidified soil failed, therefore a new, specific DNA isolation method was established. Ureolytic activity, detected in soil extracts as well as in isolated Bacillus sp. strains may be considered as a tool for the bioremediation of acidified soils with high sulfate content.

Keywords

  • acidified soil microflora
  • DNA isolation specific method
  • soil bacteria
  • soil biochemical activity
access type Open Access

Study of Patterns and Markers of Human Immune Deficiency Virus -1 (HIV-1) Progression and Unemployment Rate among Patients from Alexandria, Egypt

Published Online: 04 Dec 2017
Page range: 519 - 527

Abstract

Abstract

Middle East and North Africa (MENA) new HIV cases show the highest increase among all regions in the world. Even though Egypt has a low prevalence among the general population (< 0.02%), a national HIV epidemic occurs in certain population risk groups. The current study was conducted to asses clinical and immunological disease progression; following up viral load (VL) and detecting delta-32 CCR5 genotype polymorphism in selected cases, determining unemployment rate and identify predictors of employment for HIV-cases. A cross sectional design was adopted. HIV infected cases attending Alexandria Fever Hospital (AFH) for one year. Interview questionnaire and four CD+4 counts were done for all patients, HIV VL and delta-32 CCR5 polymorphism were done for selected cases. Sexual transmission and drug abuse are the most important risk factors. Infectious comorbidity increases the rate of HIV progression. CD4+ count at the end of the study; CD+4 (4), count was significantly higher than all other CD4+ readings among the whole cohort and among the treated group. Also, VL at the end of the study; VL(2), was significantly higher than VL(1) among the untreated group. Unemployment rate was 40%. Male gender and obtaining vocational training were significant predictors of employment. It can be concluded that having a family member living with HIV and drug abusers are high risk groups for HIV acquisition. Factors responsible for progression of HIV should be further investigated. Antiretroviral therapy is very effective in checking HIV replication rate, delaying the progression of HIV, reconstituting the immune response and should be available for all cases detected.

Keywords

  • Delta-32 CCR5 sequencing
  • HIV progression patterns
  • HIV-RNA viral load
  • HIV virus
  • unemployment rate among HIV cases
access type Open Access

Analyses of Plasmids Harbouring Quinolone Resistance Determinants in Enterobacteriaceae Members

Published Online: 04 Dec 2017
Page range: 529 - 532

Abstract

Abstract

The aim of this study was to explore the plasmid characteristics of eight clinical Enterobacteriaceae strains containing extended broad spectrum beta-lactamases and plasmid-mediated quinolone resistance. Plasmids were transferred by conjugation or transformation and resistance determinants were investigated by PCR. We showed that at least one plasmid harbouring qnrB or qnrS determinant was transferred by conjugation in five isolates. QepA determinant was confirmed to be on a non-conjugative plasmid. We found at least one beta-lactamase gene in seven of the eight clinical isolates having plasmid-mediated quinolone resistance, which indicated that these two resistance determinants were mostly on the same conjugative plasmids.

Keywords

  • beta-lactamase
  • ESBL-producing
  • plasmid-mediated quinolone resistance
access type Open Access

Inhibition of Multidrug-Resistant Gram-Positive and Gram-Negative Bacteria by a Photoactivated Porphyrin

Published Online: 04 Dec 2017
Page range: 533 - 536

Abstract

Abstract

The authors studied the in vitro antibacterial activity of the photo-activated porphyrin meso-tri(N-methyl-pyridyl), mono(N-tetradecylpyridyl)porphine (C14) against four multidrug-resistant bacteria: Staphylococcus aureus, Enterococcus faecalis (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative). Using 10 μg/ml of porphyrin and 60 sec irradiation we observed the remarkable susceptibility of S. aureus and E. faecalis to treatment while, under the same conditions, E. coli and P. aeruginosa showed very low susceptibility. In a later stage, suspensions of Gram-negative bacteria were processed with EDTA before photo-activation, obtaining a significant decrease in viable counts. In view of the results, if the combination of low porphyrin concentrations and short irradiation times will be effective in vivo also, this approach could be a possible alternative to antibiotics, in particular against localized infections due to multidrug-resistant microorganisms.

Keywords

  • antibiotic-resistant bacteria
  • laser light irradiation
  • porphyrin
  • photo-activation treatment
access type Open Access

Metagenomic Profiling of the Bacterial Community Changes from Koji to Mash Stage in the Brewing of Soy Sauce

Published Online: 04 Dec 2017
Page range: 537 - 541

Abstract

Abstract

The improvement of soy sauce fermentation is restricted by the insufficient information on bacterial community. In this study, bacterial communities in the koji and mash stage were compared based on next-generation sequencing technology. A total of 29 genera were identified in the koji stage, while 34 in the mash stage. After koji stage, 7 genera disappeared and 12 new genera appeared in the mash stage. The dominant bacteria were Kurthia, Weissella and Staphylococcus in the koji stage and Staphylococcus, Kurthia, Enterococcus and Leuconostoc in the mash stage. The results provided insights into the microbial communities involved in soy sauce fermentation.

Keywords

  • metagenomics
  • microbial community
  • next-generation sequencing
  • soy sauce fermentation
access type Open Access

Seroprevalence of Rubella and Cytomegalia in Young Women from Biała Podlaska District

Published Online: 04 Dec 2017
Page range: 543 - 545

Abstract

Abstract

The aim of this study was to analyze the seroprevalence of rubella and cytomegalia among young women. The study included 175 healthy women from the Biała Podlaska District, aged 16 to 35 years. Anti-rubella and anti-CMV IgG were determined by ELISA. 172 (98.3%) study subjects tested positive for rubella antibodies, 1 (0.6%) was seroindeterminate and 2 (1.1%) were seronegative. CMV antibodies were detected in 119 (68.0%) participants; the series included also 1 (0.6%) seroindeterminate and 55 (31.4%) seronegative women. The levels of rubella and CMV antibodies were not significantly affected by age, place of residence and educational level of the study subjects.

Keywords

  • cytomegalovirus
  • seroprevalence in women
32 Articles
access type Open Access

Transferrin and Lactoferrin – Human Iron Sources for Enterococci

Published Online: 04 Dec 2017
Page range: 419 - 426

Abstract

Abstract

To overcome limitations in iron acquisition, enterococci have evolved a number of mechanisms to scavenge iron from the host iron-binding proteins – transferrin (TR) and lactoferrin (LF). The aim of this study was to demonstrate the mechanisms by which enterococci utilize human TR and LF bound iron. The study included two strains of Enterococcus faecalis grown in iron-deficient and iron-excess media respectively. The binding activity of both proteins was monitored using proteins labelled with 125I. The uptake of iron by enterococci was determined using 59Fe labelled proteins. Reduction of iron bound to TR and LF was assayed with ferrozine. The proteolytic cleavage of TR and LF was visualized by SDS-polyacrylamide gel electrophoresis. The siderophore activity was measured with chrome azurol S. The study revealed that enterococci use several ways to acquire iron from TR and LF, such as iron chelating siderophores, iron reduction – facilitated iron release, protein degradation – promoted iron release, and receptor mediated capture of the iron-host protein complexes. The broad spectrum of iron acquisition mechanisms used by enterococci may play a significant role in the colonization of the human body and the resulting pathogenicity.

Keywords

  • spp
  • iron acquisition
  • lactoferrin
  • siderophores
  • transferrin
access type Open Access

The Prevalence of Exoenzyme S Gene in Multidrug-Sensitive and Multidrug-Resistant Pseudomonas aeruginosa Clinical Strains

Published Online: 04 Dec 2017
Page range: 427 - 432

Abstract

Abstract

Pseudomonas aeruginosa rods are one of the most commonly isolated microorganisms from clinical specimens, usually responsible for nosocomial infections. Antibiotic-resistant P. aeruginosa strains may present reduced expression of virulence factors. This fact may be caused by appropriate genome management to adapt to changing conditions of the hospital environment. Virulence factors genes may be replaced by those crucial to survive, like antimicrobial resistance genes. The aim of this study was to evaluate, using PCR, the occurrence of exoenzyme S-coding gene (exoS) in two distinct groups of P. aeruginosa strains: 83 multidrug-sensitive (MDS) and 65 multidrug-resistant (MDR) isolates. ExoS gene was noted in 72 (48.7%) of the examined strains: 44 (53.0%) MDS and 28 (43.1%) MDR. The observed differences were not statistically significant (p = 0.1505). P. aeruginosa strains virulence is rather determined by the expression regulation of the possessed genes than the difference in genes frequency amongst strains with different antimicrobial susceptibility patterns.

Keywords

  • exoenzyme S
  • multidrug sensitive
  • multidrug resistant
  • virulence genes
access type Open Access

Temperature, pH and Trimethoprim-Sulfamethoxazole Are Potent Inhibitors of Biofilm Formation by Stenotrophomonas maltophilia Clinical Isolates

Published Online: 04 Dec 2017
Page range: 433 - 438

Abstract

Abstract

Stenotrophomonas maltophilia, an opportunistic pathogen usually connected with healthcare-associated infections, is an environmental bacterium. Intrinsic resistance to multiple antibiotics, with different virulence determinants in the last decade classified this bacterium in the group of global multiple drug resistant (MDR) organism. S. maltophilia clinical isolates, were collected from tertiary care pediatric hospital in Belgrade, Serbia to investigate influence of different factors on biofilm formation, kinetics of biofilm formation for strong biofilm producers and effect of trimethoprim-sulfamethoxazole (TMP/SMX) on formed biofilm. Most of the isolates (89.8%) were able to form a biofilm. Analysis of biofilm formation in different growth conditions showed that changing of temeperature and pH had the stronggest effect on biofilm formation almost equally in group of cystic fibrosis (CF) and non-CF strains. TMP/SMX in concentration of 50 μg/ml reduced completely 24 h old biofilms while concentration of 25 μg/ml effects formed biofilms in a strain dependent manner. Among strains able to form strong biofilm CF isolates formed biofilm slower than non-CF isolates, while shaking conditions did not affect biofilm formation. Swimming motility was detected in both CF and non-CF isolates, however more motile strain formed stronger biofilms. This study suggests that temperature, pH and TMP/SMX had the strongest influence on biofilm formation in analyzed collection of S. maltophilia. A positive correlation between motility and strength of formed biofilm was demonstrated.

Keywords

  • biofilm
  • cystic fibrosis
  • opportunistic pathogen
  • trimethoprim-sulfamethoxazole
access type Open Access

Prevalence, Influencing Factors, Antibiotic Resistance, Toxin and Molecular Characteristics of Staphylococcus aureus and MRSA Nasal Carriage among Diabetic Population in the United States, 2001–2004

Published Online: 04 Dec 2017
Page range: 439 - 448

Abstract

Abstract

Diabetic population were reported more likely to suffer carriage and infection with Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA) than non-diabetic population. We aim to elucidate the prevalence and characteristics of S. aureus and MRSA nasal carriage among diabetic population in the United States National Health and Nutrition Examination Survey, 2001–2004. Univariate analyses were conducted using Chi-square test, Fisher’s exact probability test or student t test, as appropriate. Multivariate analysis using logistic regression was conducted to assess the association between influencing factors and S. aureus and MRSA nasal carriage. 1010 diabetic participants were included in the study. The prevalence of S. aureus and MRSA nasal carriage were 28.32% and 1.09%, respectively. After the logistic regression, ever had a painful sensation or tingling in hands or feet past three months (Odds Ratio [OR] = 0.359, 95% Confidence Interval [CI], 0.146–0.882) was significant among S. aureus nasal carriage and gender (OR = 3.410, 95% CI, 1.091–10.653) was significant among MRSA nasal carriage. The proportions of staphylococcal enterotoxin (SE) A, SEB, SEC, SED, Toxic-shock syndrome toxin-1, and Panton Valentine Leukocidin toxin among S. aureus strains were 18.75%, 3.13%, 12.50%, 15.63%, 28.13%, and 9.38%, respectively. 63.63% of MRSA strains were community-acquired, 27.27% were hospital-acquired, and 9.09% were non-typeable. Diabetic patients might be more likely to carry S. aureus and MRSA in the United States. Improving hand hygiene compliance, reducing antibiotic overuse, screening for carriers, and decolonization are recommended to reduce the spread of S. aureus and MRSA, especially in community.

Keywords

  • diabetics
  • MRSA
  • nasal carriage
  • NHANES
access type Open Access

Production, Characterization and Valuable Applications of Exopolysaccharides from Marine Bacillus subtilis SH1

Published Online: 04 Dec 2017
Page range: 449 - 462

Abstract

Abstract

Exopolysaccharides (EPSs) are high molecular weight polymers consisting of different sugar residues they are preferable for replacing synthetic polymers as they are degradable and nontoxic. Many microorganisms possess the ability to synthesize and excrete exopolysaccharides with novel chemical compositions, properties and structures to have potential applications in different fields. The present study attempt to optimize the production of EPS by marine Bacillus subtilis SH1 in addition to characterization and investigation of different valuable applications. Effect of medium type, incubation period and pH were studied using the one factor at a time experiments. It was shown that the highest productivity (24 gl–1) of exopolysaccharides was recorded by using yeast malt glucose medium with pH 9 at the fourth day of incubation. Experimental design using Response Surface Methodology (RSM) was applied to optimize various nutrients at different concentrations. The finalized optimized medium contained (gl–1) glucose (5), peptone (2.5), yeast extract (4.5) and malt extract (4.5) increased the production of EPS to 33.8 gl–1 with1.4 fold increase compared to the basal medium. Chemical characterization of the extracted EPS showed that, FTIR spectra exhibited bands at various regions. Moreover, HPLC chromatogram indicated that the EPS was a heteropolysaccharide consisting of maltose and rhamnose. The study was extended to evaluate the potentiality of the extracted polysaccharides in different medical applications. Results concluded that, EPS exhibited antibacterial activity against Aeromonas hydrophila, Pseudomonas aeruginosa and Streptococcus faecalis and the highest antibacterial activity (7.8, 9 and 10.4 AU/ml) was against S. faecalis at 50, 100 and 200 mg/ml respectively. The EPS exhibited various degree of antitumor effect toward the tested cell lines (MCF-7, HCT-116 and HepG2). In addition, EPS exhibited antiviral activity at 500 μg/ml. The antioxidant capacity increased with increasing the concentration of the sample. Scanning electron microscopic analysis showed that EPS had compact film-like structure, which could make it a useful in the future applications as in preparing plasticized film.

Keywords

  • SH1
  • anticancer
  • antiviral
  • exopolysaccharides
  • response surface methodology
access type Open Access

Characterisation of Antimicrobial Properties of Extracts of Selected Medicinal Plants

Published Online: 04 Dec 2017
Page range: 463 - 472

Abstract

Abstract

The scope of the experiments included analysis of the antimicrobial activity of ethanolic, methanolic and aqueous extracts against bacterial and fungal cultures and determination of the minimum inhibitory concentration of plant extracts tested microbial growth. Analysis of the antifungal and antibacterial activity was carried out by the disc diffusion method using paper discs. In the experiment 11 species of microorganisms – 8 bacterial and 3 fungal strains were used. The highest antimicrobial activity against the tested strains was demonstrated by black elder (Sambucus nigra L.), black locust (Robinia pseudoacacia L.) and lingonberry (Vaccinium vitis-idaea L.) extracts. The study showed the diverse morphological activity of specific parts of elderberry and quince, which is the effect of different polyphenolic profile of these plants. The yeast Saccharomyces cerevisiae, Escherichia coli, Pseudomonas putida and Bacillus subtilis showed the highest sensitivity to the effect of extracts of the analysed plants. As a positive control three antibiotics – amphotericin B, vancomycin and amoxicillin with clavulanic acid were used.

Keywords

  • L.
  • L.
  • L.
  • antimicrobial activity
  • medicinal plants
access type Open Access

Characterization of Bacteriocin-Producing Lactic Acid Bacteria Isolated from Native Fruits of Ecuadorian Amazon

Published Online: 04 Dec 2017
Page range: 473 - 481

Abstract

Abstract

Tropical, wild-type fruits are considered biodiverse “hotspots” of microorganisms with possible functional characteristics to be investigated. In this study, several native lactic acid bacteria (LAB) of Ecuadorian Amazon showing highly inhibitory potential were identified and characterized. Based on carbohydrate fermentation profile and 16S rRNA gene sequencing, seven strains were assigned as Lactobacillus plantarum and one strain as Weissella confusa. Using agar-well diffusion method the active synthetized components released in the neutralized and hydroxide peroxide eliminated cell-free supernatant were inhibited by proteolytic enzymes, while the activity was maintained stable after the treatment with catalase, lysozyme, α-amylase and lipase suggesting their proteinaceous nature. The inhibitory activity was stimulated by acidic conditions, upon exposure to high heat and maintained stable at different ranges of sodium chloride (4–10%). The DNA sequencing analysis confirmed the presence of plw structural gene encoding for plantacirin W in the selected L. plantarum strains. Moreover, we showed that the active peptides of Cys5-4 strains contrast effectively, in a bactericidal manner, the growth of food borne E. coli UTNEc1 and Salmonella UTNSm2, with about tree fold reduction of viable counts at the early stage of the target cell growth. The results indicated that the bacteriocin produced by selected native lactic acid bacteria strains has elevated capacity to suppress several pathogenic microorganisms implying their potential as antimicrobial agents or food preservatives.

Keywords

  • antimicrobial substances
  • bacteriocins
  • foodborne pathogens
  • lactic acid bacteria (LAB)
access type Open Access

Physiological Effects of Whey- and Milk-Based Probiotic Yogurt in Rats

Published Online: 04 Dec 2017
Page range: 483 - 490

Abstract

Abstract

In an in vitro experiment commercially available probiotic products were tested for the survival of bacteria under conditions of simulated human digestion either when used alone or mixed into yogurt. In the in vivo experiment the effects of feeding a whey- and milk-based yogurt prepared with the probiotic strain showing adequate survival in the in vitro experiment, was measured on body weight, feed consumption and immune response of rats (IgG and IgA level after immunisation), on the composition and volatile fatty acid production of the intestinal microbiota and on the structure of intestinal villi. The Lactobacillus acidophilus (LA-15) strain had inadequate surviving ability in rats. Bifidobacterium animalis ssp. lactis (BB-12) improved the composition of the intestinal microflora, whereas whey-containing product had a mild immunostimulating effect and exerted a favourable influence on the morphology of intestinal villi. The consumption of yogurts increased the depth of crypts in the ileum, which resulted in enhanced secretion and thus softer faeces.

Keywords

  • rat intestine physiology
  • physiological effect of whey and yogurt
access type Open Access

Identification of Lactobacillus delbrueckii and Streptococcus thermophilus Strains Present in Artisanal Raw Cow Milk Cheese Using Real-time PCR and Classic Plate Count Methods

Published Online: 04 Dec 2017
Page range: 491 - 499

Abstract

Abstract

The aim of this paper was to detect Lactobacillus delbrueckii and Streptococcus thermophilus using real-time quantitative PCR assay in 7-day ripening cheese produced from unpasteurised milk. Real-time quantitative PCR assays were designed to identify and enumerate the chosen species of lactic acid bacteria (LAB) in ripened cheese. The results of molecular quantification and classic bacterial enumeration showed a high level of similarity proving that DNA extraction was carried out in a proper way and that genomic DNA solutions were free of PCR inhibitors. These methods revealed the presence of L. delbrueckii and S. thermophilus. The real-time PCR enabled quantification with a detection of 101–103 CFU/g of product. qPCR-standard curves were linear over seven log units down to 101 copies per reaction; efficiencies ranged from 77.9% to 93.6%. Cheese samples were analysed with plate count method and qPCR in parallel. Compared with the classic plate count method, the newly developed qPCR method provided faster and species specific identification of two dairy LAB and yielded comparable quantitative results.

Keywords

  • artisanal cheese microflora
  • LAB identification
access type Open Access

The Determination and Correlation of Various Virulence Genes, ESBL, Serum Bactericidal Effect and Biofilm Formation of Clinical Isolated Classical Klebsiella pneumoniae and Hypervirulent Klebsiella pneumoniae from Respiratory Tract Infected Patients

Published Online: 04 Dec 2017
Page range: 501 - 508

Abstract

Abstract

Klebsiella pneumoniae strains that are commonly recognized by clinicians and microbiologists are termed as classical K. pneumoniae (cKP). A strain with capsule-associated mucopolysaccharide web is known as hypervirulent K. pneumoniae (hvKP) as it enhances the serum resistant and biofilm production. Aim is to determine and correlate various virulence genes, ESBL, serum bactericidal effect and biofilm formation of clinical isolated cKP and hvKP from respiratory tract infected patients. A total of 96 K. pneumoniae strains were isolated from sputum of respiratory tract infected patients. The isolates were performed string test, AST, ESBL virulence gene, serum bactericidal and biofilm assays. Out of 96 isolates, 39 isolates (40.6%) were identified with hypervirulent phenotypes. The number of cKP exhibiting resistance to the tested antimicrobials and ESBLs were significantly higher than that of the hvKP strains. The virulence genes of K. pneumoniae such as K1, K2, rmpA, uge, kfu and aerobactin were strongly associated with hvKP than cKP. However, no significant difference was found in FIM-1 and MrKD3 genes. ESBL producing cKP and hvKP were significantly associated with strong biofilm formation (both P < 0.05) and highly associated with bactericidal effect of serum (both P < 0.05) than cKP strains. However, neither biofilm formation nor bactericidal effect of serum was found with significant difference in between ESBL producing cKP and ESBL producing hvKP strains (both P > 0.05). Although the hvKP possess more virulence gene, but they didn’t show any significant difference between biofilm formation and bactericidal effect of serum compared with ESBL producing cKP strains.

Keywords

  • biofilm
  • ESBL
  • classical hypervirulent
  • serum resistance
  • virulence genes
access type Open Access

Characterization of Microbial Communities in Acidified, Sulfur Containing Soils

Published Online: 04 Dec 2017
Page range: 509 - 517

Abstract

Abstract

Over a period of three years, microbial communities in acidified soil with high sulfur content were analyzed. In soil water extracts ureolytic, proteolytic, oxidoreductive, and lipolytic activity were detected. The presented results indicate that the enzymatic activity of soil microbial communities varied considerably over time. Isolated 26 (80%) bacterial strains belonged to genus Bacillus sp. and were identified by cultivation and 16S rRNA methods. The commercially available procedures for bacterial DNA isolation from acidified soil failed, therefore a new, specific DNA isolation method was established. Ureolytic activity, detected in soil extracts as well as in isolated Bacillus sp. strains may be considered as a tool for the bioremediation of acidified soils with high sulfate content.

Keywords

  • acidified soil microflora
  • DNA isolation specific method
  • soil bacteria
  • soil biochemical activity
access type Open Access

Study of Patterns and Markers of Human Immune Deficiency Virus -1 (HIV-1) Progression and Unemployment Rate among Patients from Alexandria, Egypt

Published Online: 04 Dec 2017
Page range: 519 - 527

Abstract

Abstract

Middle East and North Africa (MENA) new HIV cases show the highest increase among all regions in the world. Even though Egypt has a low prevalence among the general population (< 0.02%), a national HIV epidemic occurs in certain population risk groups. The current study was conducted to asses clinical and immunological disease progression; following up viral load (VL) and detecting delta-32 CCR5 genotype polymorphism in selected cases, determining unemployment rate and identify predictors of employment for HIV-cases. A cross sectional design was adopted. HIV infected cases attending Alexandria Fever Hospital (AFH) for one year. Interview questionnaire and four CD+4 counts were done for all patients, HIV VL and delta-32 CCR5 polymorphism were done for selected cases. Sexual transmission and drug abuse are the most important risk factors. Infectious comorbidity increases the rate of HIV progression. CD4+ count at the end of the study; CD+4 (4), count was significantly higher than all other CD4+ readings among the whole cohort and among the treated group. Also, VL at the end of the study; VL(2), was significantly higher than VL(1) among the untreated group. Unemployment rate was 40%. Male gender and obtaining vocational training were significant predictors of employment. It can be concluded that having a family member living with HIV and drug abusers are high risk groups for HIV acquisition. Factors responsible for progression of HIV should be further investigated. Antiretroviral therapy is very effective in checking HIV replication rate, delaying the progression of HIV, reconstituting the immune response and should be available for all cases detected.

Keywords

  • Delta-32 CCR5 sequencing
  • HIV progression patterns
  • HIV-RNA viral load
  • HIV virus
  • unemployment rate among HIV cases
access type Open Access

Analyses of Plasmids Harbouring Quinolone Resistance Determinants in Enterobacteriaceae Members

Published Online: 04 Dec 2017
Page range: 529 - 532

Abstract

Abstract

The aim of this study was to explore the plasmid characteristics of eight clinical Enterobacteriaceae strains containing extended broad spectrum beta-lactamases and plasmid-mediated quinolone resistance. Plasmids were transferred by conjugation or transformation and resistance determinants were investigated by PCR. We showed that at least one plasmid harbouring qnrB or qnrS determinant was transferred by conjugation in five isolates. QepA determinant was confirmed to be on a non-conjugative plasmid. We found at least one beta-lactamase gene in seven of the eight clinical isolates having plasmid-mediated quinolone resistance, which indicated that these two resistance determinants were mostly on the same conjugative plasmids.

Keywords

  • beta-lactamase
  • ESBL-producing
  • plasmid-mediated quinolone resistance
access type Open Access

Inhibition of Multidrug-Resistant Gram-Positive and Gram-Negative Bacteria by a Photoactivated Porphyrin

Published Online: 04 Dec 2017
Page range: 533 - 536

Abstract

Abstract

The authors studied the in vitro antibacterial activity of the photo-activated porphyrin meso-tri(N-methyl-pyridyl), mono(N-tetradecylpyridyl)porphine (C14) against four multidrug-resistant bacteria: Staphylococcus aureus, Enterococcus faecalis (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative). Using 10 μg/ml of porphyrin and 60 sec irradiation we observed the remarkable susceptibility of S. aureus and E. faecalis to treatment while, under the same conditions, E. coli and P. aeruginosa showed very low susceptibility. In a later stage, suspensions of Gram-negative bacteria were processed with EDTA before photo-activation, obtaining a significant decrease in viable counts. In view of the results, if the combination of low porphyrin concentrations and short irradiation times will be effective in vivo also, this approach could be a possible alternative to antibiotics, in particular against localized infections due to multidrug-resistant microorganisms.

Keywords

  • antibiotic-resistant bacteria
  • laser light irradiation
  • porphyrin
  • photo-activation treatment
access type Open Access

Metagenomic Profiling of the Bacterial Community Changes from Koji to Mash Stage in the Brewing of Soy Sauce

Published Online: 04 Dec 2017
Page range: 537 - 541

Abstract

Abstract

The improvement of soy sauce fermentation is restricted by the insufficient information on bacterial community. In this study, bacterial communities in the koji and mash stage were compared based on next-generation sequencing technology. A total of 29 genera were identified in the koji stage, while 34 in the mash stage. After koji stage, 7 genera disappeared and 12 new genera appeared in the mash stage. The dominant bacteria were Kurthia, Weissella and Staphylococcus in the koji stage and Staphylococcus, Kurthia, Enterococcus and Leuconostoc in the mash stage. The results provided insights into the microbial communities involved in soy sauce fermentation.

Keywords

  • metagenomics
  • microbial community
  • next-generation sequencing
  • soy sauce fermentation
access type Open Access

Seroprevalence of Rubella and Cytomegalia in Young Women from Biała Podlaska District

Published Online: 04 Dec 2017
Page range: 543 - 545

Abstract

Abstract

The aim of this study was to analyze the seroprevalence of rubella and cytomegalia among young women. The study included 175 healthy women from the Biała Podlaska District, aged 16 to 35 years. Anti-rubella and anti-CMV IgG were determined by ELISA. 172 (98.3%) study subjects tested positive for rubella antibodies, 1 (0.6%) was seroindeterminate and 2 (1.1%) were seronegative. CMV antibodies were detected in 119 (68.0%) participants; the series included also 1 (0.6%) seroindeterminate and 55 (31.4%) seronegative women. The levels of rubella and CMV antibodies were not significantly affected by age, place of residence and educational level of the study subjects.

Keywords

  • cytomegalovirus
  • seroprevalence in women

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