Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study

AIM AND BACKGROUND

This study aimed to explore the potential synergistic interaction of virgin coconut oil (VCO) and virgin olive oil (VOO) mixture against Streptococcus sanguinis, Streptococcus mutans, and Lactobacillus casei in a single and mixture species through the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antiadherence, and antibiofilm activities.

MATERIALS AND METHODS

The broth microdilution technique was used to individually determine the MIC of both oils and an oil mixture (in the ratio of 1:1) in a 96-well microtiter plate. As for the MBC, the subcultured method was used. The fractional inhibitory concentration index (ΣFIC) was determined to identify the interaction types between both oils. The oil mixture at its MIC was then tested on its antibiofilm and antiadherence effect.

RESULTS

The MIC of the oil mixture against the tested microbiota was 50-100%. The oil mixture was bactericidal at 100% concentration for all the mentioned microbes except S. mutans. The ΣFIC value was 2 to 4, indicating that the VCO and VOO acted additively against the microbiota. Meanwhile, the oil mixture at MIC (50% for S. sanguinis and L. casei; 100% for S. mutans and mixture species) exhibited antiadherence and antibiofilm activity toward the microbiota in mixture species.

CONCLUSION

The oil mixture possesses antibacterial, antibiofilm, and antiadherence properties toward the tested microbiota, mainly at 50-100% concentration of oil mixture. There was no synergistic interaction found between VCO and VOO.

CLINICAL SIGNIFICANCE

Children and individuals with special care may benefit from using the oil mixture, primarily to regulate the biofilm formation and colonization of the bacteria. Furthermore, the oil mixture is natural and nontoxic compared to chemical-based oral healthcare products. How to cite this article: Ng YM, Sockalingam SNMP, Shafiei Z, et al. Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study. J Contemp Dent Pract 2024;25(3):260-266.

Biosorption of lead ion by lactic acid bacteria and the application in wastewater

Through the study of biosorption of Pb2+ by lactic acid bacteria, two strains called CN-011 and CN-005 with high tolerance and great adsorption to lead were screened. The minimum bactericidal concentration of lead ions for both CN-011 and CN-005 was 1.45 mmol/L. The optimal culture conditions for the removal of 30 mg/L lead ions were achieved by culturing lactic acid bacteria at an initial pH of 7.0, 37 °C and 120 rpm for 48 h. The adsorption rate of CN-011 and CN-005 for Pb2+ were 85.95% and 86.78%, respectively. In simulated wastewater samples, the average adsorption rate of Pb2+ was 73.38% for CN-011 and 74.15% for CN-005. The mechanism of biosorption was characterized by Fourier Transform infrared spectroscopy, Scanning Electron Microscope-Energy Dispersive Spectrometer, X-ray Photoelectron Spectroscopy, which revealed that Pb2+ mainly reacted with hydroxyl ions in peptidoglycan or polysaccharide, and carboxylate radical in teichoic acid or protein on the surface of lactic acid bacteria cell wall. The deposits produced on the bacterial surface were identified as lead oxide and lead nitrate.

Burden of biocide resistance among multidrug-resistant bacteria isolated from various clinical specimens in a tertiary care hospital

BACKGROUND

Most studies on biocide resistance and its genetic determinants arise from environmental or food-borne microbial isolates and only a few from clinically relevant isolates.

OBJECTIVES

This study determines the proportion of biocide resistance against five commonly used biocides and detects biocide resistance genes among MDR bacterial isolates using PCR.

METHODS

Consecutive MDR isolates (n ​= ​180) were included (30 each of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Staphylococcus aureus, and Enterococcus species) from clinical specimens of various inpatient units at JIPMER. The isolates were challenged at 0.5,1 and 2 Macfarland (McF) inoculum with discrete dilutions of disinfectants. The minimum bactericidal concentrations (MBCs) for 70% Ethanol, 1.5% Cresol, 2% Glutaraldehyde, 1% Cetrimide, and 1% Chlorhexidine were determined for the isolates using ATCC reference strains as controls. PCR was performed targeting qac A/B, G; smr; and nfx B genes.

RESULTS

For all biocides, MDR isolates had MBCs less than the maximum MBCs of ATCC strains. For MDR K. pneumoniae, A. baumannii, and P. aeruginosa, the highest MBCs of chlorhexidine and cetrimide were ≥75 and ​≥ ​150 ​μg/ml respectively at 0.5 McF inoculum; whereas these organisms grew at higher inoculum (2McF) even at commercially recommended biocidal concentration (1%) corresponding to 750 and 1500 ​μg/ml of chlorhexidine and cetrimide respectively. Meanwhile, the highest MBCs of MDR E. coli were 75 and 150 ​μg/ml for chlorhexidine and cetrimide respectively. Interestingly, the Gram-positive cocci survived the action of up to 35% ethanol. The nfxB and qacG genes were detected in 87% and 6.67% of MDR P. aeruginosa isolates respectively with no biocide resistance genes detected among the other organisms.

CONCLUSIONS

Biocide dilutions challenged with higher inoculum indicated a narrow margin of effectiveness for certain biocides. Although a significant proportion of clinical MDR isolates of P. aeruginosa harbored biocide resistance genes, this finding had no phenotypic correlation.

Evaluation of the antibacterial effect of hydroalcoholic extract of the galls of Quercus infectoria on Aggregatibacter actinomycetemcomitans

Background

Aggregatibacter actinomycetemcomitans (Aa) plays a vital role in some destructive forms of periodontitis. While mechanical and chemical plaque control is the first step in periodontitis treatment, side effects of adjunctive chemical agents such as chlorhexidine (CHX) mouthwash have led to the application of natural alternatives with minimal side effects. Therefore, this study evaluated the antibacterial effect of the hydroalcoholic extract of Quercus infectoria (Qi) galls on Aa in vitro.

Methods

The hydroalcoholic extract of Qi was obtained by the maceration method, and Aa bacterial strain was cultured. The inhibition zone diameter was measured through the agar well diffusion method. Also, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined by the broth microdilution method. All the experiments were repeated three times. 0.2% CHX was used as a control.

Results

The inhibition zone diameter of Aa increased with increasing concentration of Qi extract. While MIC and MBC values for CHX were 0.0039 and 0.0078 mg/mL, respectively, both MIC and MBC values of the Qi extract for this bacterium were similar, i.e., 2.5 mg/mL, which was significantly higherd.

Conclusion

Since other in vivo studies have confirmed the other properties of this extract and its safety in terms of cytotoxicity and mutagenicity, hydroalcoholic extract of Qi may be used in mouthwashes or local delivery systems to affect periodontal biofilm.

Engineering nanoscale hierarchical morphologies and geometrical shapes for microbial inactivation in aqueous solution

Here, we study the effect of hierarchical and one-dimensional (1D) metal oxide nanorods (H-NRs) such as γ-Al₂O₃, β-MnO₂, and ZnO as microbial inhibitors on the antimicrobial efficiency in aqueous solution. These microbial inhibitors are fabricated in a diverse range of nanoscale hierarchical morphologies and geometrical shapes that have effective surface exposure, and well-defined 1D orientation. For instance, γ-Al₂O₃ H-NRs with 20 nm width and ˂0.5 μm length are grown dominantly in the [400] direction. The wurtzite structures of β-MnO₂ H-NRs with 30 nm width and 0.5-1 μm length are preferentially oriented in the [100] direction. Longitudinal H-NRs with a width of 40 nm and length of 1 μm are controlled with ZnO wurtzite structure and grown in [0001] direction. The antimicrobial efficiency of H-NRs was evaluated through experimental assays using a set of microorganisms (Gram-positive Staphylococcus aureus, Bacillus thuriginesis, and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Minimal inhibitory and minimum bactericidal concentrations (MIC and MBC) were determined. These 1D H-NRs exhibited antibacterial activity against all the used strains. The active surface exposure sites of H-NRs play a key role in the strong interaction with the thiol units of vital bacterial enzymes, leading to microbial inactivation. Our finding indicates that the biological effect of the H-NR surface planes on microbial inhibition is decreased in the order of [400]-γ-Al₂O₃ > [100]-β-MnO₂ > [0001]-ZnO geometrics. The lowest key values including MIC (1.146 and 0.250 μg/mL), MBC (1.146, 0.313 μg/mL), and MIC/MFC (0.375 and 0.375 μg/mL) are achieved for [400]-plane γ-Al₂O₃ surfaces when tested against Gram-positive and -negative bacteria, respectively. Among the three H-NRs, the smallest diameter size and length, the largest surface area, and the active exposure [400] direction of γ-Al₂O₃ H-NRs could provide the highest microbial inactivation.

Chemical composition, antioxidative‎, antibacterial‎‎, and time-kill activities of some selected plant essential oils against foodborne pathogenic and spoilage organisms

Essential oils (EOs) have been utilized as a growth inhibitor of microorganisms. This study was aimed to recognize the composition, antioxidative‎, antibacterial‎‎‎‎‎‎‎‎, and time-kill activities of Origanum vulgare, Zataria multiflora, Syzygium aromaticum; and Cinnamomum verum EOs against Listeria monocytogenes, Escherichia coli O157:H7, Shewanella putrefaciens and Pseudomonas fluorescens. Gas chromatography-mass spectrometry was used to determine the chemical composition of EOs. Disc diffusion, minimum inhibitory concentration, minimum bactericidal concentration, and time-kill methods were used to determine the antibacterial ‎‎activity of EOs. The antioxidative ‎ activity of EOs were determined by 2, 20-diphenyl-1-picrylhydrazyl radical scavenging and ferric reducing antioxidative ‎ power methods. All EOs exhibited antibacterial ‎‎activity, however, Z. multiflora EO was the most effective followed by O. vulgare EO. The lowest antibacterial‎‎‎‎‎ activity was observed in C. verum EO. The most sensitive among tested bacteria to Z. multiflora and O. vulgare EOs was E. coli O157:H7 and to S. aromaticum; and C. verum EOs were S. putrefaciens and P. fluorescens, respectively. Z. multiflora and O. vulgare EOs were able to kill 85.00% and 80.00% of the E. coli O157: H7 and S. putrefaciens cells in 4 hr, respectively. The highest antioxidative ‎activity was observed in Z. multiflora EO. The tested EOs showed the highest antioxidative ‎activity at a concentration of 2.00 g L^-1. Ferric reducing antioxidant power value of Z. multiflora, O. vulgare, S. aromaticum and C. verum was 2.01 ± 0.03, 1.47 ± 0.04, 1.01 ± 0.03, and 0.66 ± 0.34, respectively. High concentrations of tested EOs showed a decrease in antioxidative ‎ activity.

Antimicrobial and Antibiofilm Effect of Cranberry Extract on Streptococcus mutans and Lactobacillus acidophilus: An In Vitro Study

Background

Nature has been a source of medicinal treatments since millennia and plant-based systems continue to play an essential role.

Aim

To study the antimicrobial and antibiofilm effect of cranberry on Streptococcus mutans and Lactobacillus acidophilus.

Materials and methods

The ethanolic extract of cranberry was tested against standard MTCC strains of S. mutans (MTCC 25175) and L. acidophilus (MTCC 8129) for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The time kill assay was performed to check the time-dependent bactericidal effect of the cranberry extract on microorganisms. Percentage of cell adhesion and biofilm inhibition of the dental microorganism at various doses of cranberry extract was measured by a spectrophotometer and biofilm morphology characteristics were observed under scanning electron microscopy. All the tests were carried out in triplicates. Data were computed in the SPSS software and mean/SD was determined. The results are presented in a descriptive manner; Kruskal–Wallis analysis of variance (ANOVA) and the Friedman's test were applied for comparative evaluation of the groups. p value <0.05 was considered statistically significant.

Results

The results showed that MICs of cranberry extract against S. mutans and L. acidophilus are 12.5 mg/dL and 6.125 mg/dL, respectively, and MBCs are 25 mg/dL and 12.5 mg/dL, respectively. A significant decrease in the biofilm formation and cell adhesion of microorganisms at MIC (50%) and MBC (70%) was observed as compared to control as observed under a spectrophotometer and a scanning electron microscope.

Conclusion

This study has identified bactericidal, bacteriostatic, and antibiofilm effects of cranberry extract against S. mutans and L. acidophilus in a time-dependent and dose-dependent manner.

How to cite this article

Singhal R, Patil P, Siddibhavi M, et al. Antimicrobial and Antibiofilm Effect of Cranberry Extract on Streptococcus mutans and Lactobacillus acidophilus: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(1):11–15.

Spectroscopic characterization and antimicrobial activity of nanoparticle doped cyclodextrin polyurethane bionanosponge

This study reports on the spectroscopic characterization and antimicrobial potency of polyurethane cyclodextrin co-polymerized phosphorylated multiwalled carbon nanotube-doped Ag-TiO₂ nanoparticle (pMWCNT-CD/Ag-TiO₂) bionanosponge nanocomposite. The synthesis of pMWCNT-CD/Ag-TiO₂ bionanosponge nanocomposite was carried out through the combined processes of amidation and polymerization reactions as well as the sol-gel method. The native nanosponge cyclodextrin and phosphorylated multiwalled carbon nanotube-nanosponge CD (pMWCNT-CD) polyurethanes were also prepared, and their antimicrobial activities carried out for comparison purposes. The synthesized bionanosponge polyurethane materials were characterized using Fourier-transform infrared (FTIR) spectroscopy, Laser Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to give clear information regarding their structural, and dynamic physicochemical properties. The potency tests of the synthesized compounds were carried out against three bacterial strains Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and two fungal representatives Aspergillus ochraceus and Aspergillus fumigatus, using the disc diffusion method. Micro dilution and agar plating were used to determine the minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC), respectively. The results obtained revealed that pMWCNT-CD/Ag-TiO₂ exhibits superior antibacterial and antifungal activities when compared to the other bionanosponge polymers tested. Thus, the bionanosponge polyurethane pMWCNT-CD/Ag-TiO₂ nanocomposite can be considered as an active antimicrobial compound (AMC).

Antimicrobial activity of a selection of organic acids, their salts and essential oils against swine enteropathogenic bacteria

Background

Accurate screening of new alternative antimicrobial compounds is essential for their use to control pathogens in swine production due to the replacement of antibiotics and zinc oxide. Most in vitro studies have separately reported the antimicrobial activity of organic acids and essential oils (EOs) using diverse methods for susceptibility testing. In addition, in vitro outcomes can help in the selection of the suitable antimicrobial compound and effective combinations of these compounds in the control of pathogens of interest in pork production. Therefore, the aim of this study is to determinate the antibacterial activity of six organic acids and six EOs against Escherichia coli, Salmonella spp. and Clostridium perfringens isolates, some of them multi-resistant to antibiotics, from swine origin. The synergistic effects between the products with higher activity for each bacteria were also calculated.

Results

All products tested showed activity against at least one bacterial species, except for black pepper EO. The results showed that formic acid with the shortest chain length was the most effective against E. coli and Salmonella spp., while the sodium salt of coconut fatty acid distillates with long chain acids was the most effective against C. perfringens. The susceptibility of isolates tested to EOs was similar, a result that demonstrates a similar activity of these products against phylogenetically unrelated pathogens. In addition, an additive effect was shown for carvacrol-oregano EO for E. coli, formic acid-carvacrol and formic acid-thymol for Salmonella spp. and carvacrol-cinamaldehyde for C. perfringens.

Conclusions

The susceptibility of isolates to EOs was similar, a result that demonstrates a similar activity of these products against phylogenetically unrelated pathogens in contrast to organic acids. In addition, an additive effect was shown for several combinations of these compounds.

Antimicrobial activity and mechanisms of multiple antimicrobial peptides isolated from rockfish Sebastiscus marmoratus

Pathogenic disease is a major factor affecting the aquaculture of the rockfish Sebastiscus marmoratus, an important commercial species inhabiting the nearshore waters of the Western Pacific Ocean. Antimicrobial peptides (AMPs), as critical components of innate immunity, have been considered as promising antibiotic substitutes. The aims of this study were 1) to identify major AMPs in the rockfish, 2) to assess their antimicrobial activity and 3) to evaluate their potential therapeutic application. Six AMPs were identified, Hepcidin 1, liver-expressed antimicrobial peptide 2 (LEAP-2), Piscidin, Moronecidin, NK-lysin and β-defensin through analysis of the liver transcriptome of S. marmoratus. The transcriptional expression profiles of these AMPs were investigated by real-time quantitative PCR (RT-qPCR). These AMPs showed tissue-specific distribution patterns, and S. marmoratus displays a time-, dose- and tissue-dependent expression of AMPs in response to lipopolysaccharide (LPS) challenge. While the synthetic peptides of LEAP-2 and Moronecidin exerted broad-spectrum antimicrobial activity against important aquatic pathogens in vitro by directly disrupting microbial membrane, and no cytotoxicity against murine hepatic cells was observed at the effective concentrations from 5 μM to 40 μM. The existence of multiple AMPs and their distinct tissue distribution patterns and inducible expression patterns suggests a sophisticated, highly redundant, and multilevel network of antimicrobial defensive mechanisms of S. marmoratus. Therefore, S. marmoratus-derived AMPs appear to be potential therapeutic applications against pathogen infections in aquaculture.

Antibacterial effect of copper sulfate against multi-drug resistant nosocomial pathogens isolated from clinical samples

Background and Objective:

With the emergence of antibiotic resistance and the hospital acquired infection, the interest for antimicrobial agents has recently increased again in public health. Copper is recommended as a supplementary method of increasing biological safety in the hospital environment. The objective of this study was to determine the antibacterial activity of copper sulfate salts on strains of bacterial pathogens isolated from different clinical pictures in different health establishment in Algeria.

Methods:

A total of 25 different bacterial isolates (16 Enterobacteriaceae, 5 Staphylococci, and 4 Pseudomonas) were tested for susceptibility to copper sulfate using minimum inhibitory concentration (MIC-Cu) and minimum bactericidal concentrations (MBC-Cu) determinations. All isolates were also tested for susceptibility to six antibiotics.

Results:

Antibiotic susceptibility studies revealed that 100% of isolates were resistant to one or more antibiotics. Fifty two percent of isolates were very susceptible to copper sulfate, with MICs ranging from 100 to 200 µg/ml. MBC-Cu = 1600 μg/ml showed the best bactericidal effect against the great majority of studied bacteria (52%). A good bactericidal activities of copper sulfate were recorded against Proteus vulgaris and Staphylococcus aureus (MBC/MIC=1). The Gram-negative bacteria isolates which were copper resistant also showed a high resistance to chloramphenicol (r=0.78) and Trimethoprime (r=0.61). Furthermore, the strains that were no-susceptible to three different antimicrobial classes (Escherichia coli, Staphylococcus saprophyticus) were not resistant to copper sulfate.

Conclusion:

Copper sulfate salts has significant antibacterial activity against multi-drug resistant nosocomial pathogens.

Chlorhexidine sensitivity in staphylococci isolated from patients with central line-associated bloodstream infection

Since 2011, 2% chlorhexidine in 70% isopropyl alcohol (2% chlorhexidine tincture) has been widely used in Korea. To investigate changes in chlorhexidine sensitivity of staphylococci causing central line-associated bloodstream infections, 264 blood culture isolates from adult patients treated in intensive care units of five university hospitals between 2008 and 2016 were analysed. We observed no significant changes in chlorhexidine minimum inhibitory and bactericidal concentrations, or in the prevalence of resistance-associated genes before and after introduction of 2% chlorhexidine tincture. Thus, there was no evidence of increased resistance to chlorhexidine in staphylococci causing central line-associated bloodstream infections.

[Antiseptic effect of compound lysostaphin disinfectant and its preventive effect on infection of artificial dermis after graft on full-thickness skin defect wound in rats]

Objective: To study the antiseptic effect of compound lysostaphin disinfectant and its preventive effect on infection of artificial dermis after graft on full-thickness skin defect wound in rats. Methods: (1) Each one standard strain of Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus were selected. Each 20 clinical strains of Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus were collected from those isolated from wound exudates of burn patients hospitalized in our wards from January 2014 to December 2016 according to the random number table. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of compound lysostaphin disinfectant to above-mentioned strains were detected. The experiment was repeated 3 times. Compared with the corresponding standard strain, the clinical strain with higher MIC and/or MBC was considered as having decreased sensitivity to the disinfectant. The percentage of strains of each of the three kinds of bacteria with decreased sensitivity was calculated. (2) Artificial dermis pieces were soaked in compound lysostaphin disinfectant for 5 min, 1 h, 2 h, and 4 h, respectively, with 21 pieces at each time point. After standing for 0 (immediately), 12, 24, 36, 48, 60, 72 h (with 3 pieces at each time point), respectively, the diameters of their inhibition zones to standard strains of Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus were measured. The experiment was repeated 3 times. The shortest soaking time corresponding to the longest standing time, after which the disinfectant-soaked artificial dermis could form an effective inhibition zone (with diameter more than 7 mm), was the sufficient soaking time of the disinfectant to the artificial dermis. (3) Forty Sprague-Dawley rats were divided into post injury day (PID) 3, 7, 14, and 21 sampling groups according to the random number table, with 10 rats in each group. A full-thickness skin defect wound with a diameter of 20 mm was made on both sides of the spine on the back of each rat. Immediately after injury, the artificial dermis without any treatment was grafted on the wound on left side of the spine (hereinafter referred to as control wound), while the sufficiently soaked artificial dermis with compound lysostaphin disinfectant was grafted on the wound on right side of the spine (hereinafter referred to as disinfectant wound). On PID 3, 7, 14, and 21, the gross condition of wounds of all the surviving rats was observed, and the new infection rates of control wounds and disinfectant wounds were calculated. Then, the rats in the sampling group with corresponding time were killed, and the full-thickness wound tissue containing artificial dermis was collected for quantitative analysis of bacteria. Bacteria content of the uninfected control wounds and that of the uninfected disinfectant wounds were compared. Data were processed with chi-square test and Wilcoxon rank sum test. Results: (1) The MIC of compound lysostaphin disinfectant to standard strains of Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter baumannii were 1/32, 1/32, and 1/512 of the original concentration of the disinfectant, respectively, and the MBC were 1/32, 1/16, and 1/512 of the original concentration of the disinfectant, respectively. The percentages of clinical strains of Klebsiella pneumoniae, Acinetobacter baumannii and Staphylococcus aureus with decreased sensitivity to compound lysostaphin disinfectant were 15% (3/20), 20% (4/20), and 10% (2/20), respectively. (2) After being soaked in compound lysostaphin disinfectant for 2 and 4 h, the longest standing time, after which the artificial dermis could form an effective inhibition zone against Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus, were 24, 36, and 48 h respectively, longer than 12, 24, and 24 h of soaking for 5 min and 24, 24, and 36 h of soaking for 1 h. The sufficient soaking time of compound lysostaphin disinfectant to artificial dermis was 2 h. (3) On PID 3, no infection symptom was observed in all the wounds, and so both the new infection rate of control wounds and that of disinfectant wounds were 0. The artificial dermis was transparent but not well connected with the wound. On PID 7, the new infection rate of control wounds was 20.00% (6/30), which was obviously higher than 3.33% (1/30) of disinfectant wounds, χ(2)=4.043, P<0.05. On the infected wound, a large amount of purulent exudates were observed, and the artificial dermis was not connected with the wound and degraded partially. On the uninfected wound, artificial dermis was transparent and had a partial connection with the wound. On PID 14 and 21, no new infected wound was observed, and so both the new infection rate of control wounds and that of disinfectant wounds were 0. There was no obvious improvement on the infected wounds. The collagen layers of artificial dermis in the uninfected wound established a good connection with the wound and were separating from the silica gel layer gradually. Infection occurred in 2, 3, 1 control wound (s) in PID 7, 14, and 21 sampling groups, respectively, and in 1 disinfectant wound in PID 14 sampling group. The bacteria content of the infected wounds tissue was 0.79×10(6) to 7.22×10(9) colony-forming unit (CFU)/g. The bacteria content of uninfected control wounds tissue in PID 3, 7, and 14 sampling groups were (3.43±1.88)×10(2,) (2.37±0.43)×10(3,) and (8.40±1.03)×10(3) CFU/g, respectively, which were significantly higher than (0.33±0.12)×10(2,) (0.43±0.17)×10(3,) (2.16±0.52)×10(3) CFU/g of uninfected disinfectant wounds tissue (Z=-3.780, -3.554, -3.334, P<0.05). The bacteria content of uninfected control wounds tissue and that of uninfected disinfectant wounds tissue in PID 21 sampling group were similar (Z=-0.490, P>0.05). Conclusions: Compound lysostaphin disinfectant has quite strong antibacterial ability against Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus. Clinical strains of the three kinds of bacteria were highly sensitive to compound lysostaphin disinfectant. Saturation of absorption of compound lysostaphin disinfectant achieves in artificial dermis after 2 hours' soaking. After 24, 36, and 48 hours' standing, the soaked artificial dermis still has the antibacterial effect on Klebsiella pneumoniae, Acinetobacter baumannii, and Staphylococcus aureus, respectively. The infection rate and the bacteria content of full-thickness skin defect wound in rats are all decreased when grafted with soaked artificial dermis.

Cost-effective downstream processing of recombinantly produced pexiganan peptide and its antimicrobial activity

Antimicrobial peptides (AMPs) have significant potential as alternatives to classical antibiotics. However, AMPs are currently prepared using processes which are often laborious, expensive and of low-yield, thus hindering their research and application. Large-scale methods for production of AMPs using a cost-effective approach is urgently required. In this study, we report a scalable, chromatography-free downstream processing method for producing an antimicrobial peptide, pexiganan, using recombinant Escherichia coli (E. coli). The four helix bundle structure of the unique carrier protein DAMP4 was used to facilitate a simple and cheap purification process based on a selective thermochemical precipitation. Highly pure fusion protein DAMP4_var-pexiganan was obtained at high yield (around 24 mg per 800 mL cell culture with a final cultivation OD₆₀₀ ~ 2). The purification yield of DAMP4_var-pexiganan protein is increased twofold with a 72.9% of the protein recovery in this study as compared to the previous purification processes (Dwyer in Chem Eng Sci 105:12–21, 2014). The antimicrobial peptide pexiganan was released and activated from the fusion protein by a simple acid-cleavage. Isoelectric precipitation was then applied to separate the pexiganan peptide from the DAMP4_var protein carrier. The final yield of pure bio-produced pexiganan was 1.6 mg from 800 mL of bacterial cell culture (final cultivation OD₆₀₀ ~ 2). The minimum bactericidal concentration (MBC) test demonstrated that the bio-produced pexiganan has the same antimicrobial activity as chemically synthesized counterpart. This novel downstream process provides a new strategy for simple and probable economic production of antimicrobial peptides.

Antimicrobial activity of some plant materials used in Armenian traditional medicine

Background

Antibiotic resistance has become one of the major problems facing humanity. The need for new antimicrobials has been increased dramatically. Plants are considered as one of the most promising sources for new antimicrobials discovery. Despite relatively small area, Armenia has large diversity of flora with many endemic species. In Armenian folk medicine plant materials have been used to treat various microbial diseases since ancient times. The goal of our research was to evaluate antimicrobial efficiency of different parts of five wild plants species which are commonly used in Armenian traditional medicine.

Methods

Plant crude extracts were obtained with maceration technique using five solvents separately: distilled water, methanol, chloroform, acetone, and hexane. Agar well diffusion assay was used for initial evaluation of antimicrobial properties of plant materials against five bacterial and two yeast strains. Minimum inhibitory concentrations of the most active plant parts were determined by broth microdilution method.

Results

Crude extracts of all five tested plants expressed antimicrobial activity against at least four test strains at 500 μg ml⁻¹ concentration. Minimum inhibitory and bactericidal/fungicidal concentrations of selected plant parts were determined. Crude acetone and hexane extracts of Hypericum alpestre and acetone extract of Sanguisorba officinalis inhibited the growth of P. aeruginosa even at 64 μg ml⁻¹ concentration. Chloroform and acetone extracts of Sanguisorba officinalis exhibited cidal activity against P. aeruginosa till 256 μg ml⁻¹. Acetone was the most effective solvent for solubilizing antimicrobial compounds for almost all tested plant materials.

Conclusions

Thus, antimicrobial activity of some medicinal plants used in Armenian traditional medicine was evaluated. Some of the plants had rather low minimum bacteriostatic/bactericidal concentrations and therefore they have prospective for further more inclusive studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-017-1573-y) contains supplementary material, which is available to authorized users.

Two isoforms of piscidin from Malabar grouper, Epinephelus malabaricus: Expression and functional characterization

Two isoforms of piscidin from Malabar grouper (Epinephelus malabaricus), EmPis-1 and EmPis-2, were cloned and studied. EmPis-1 and EmPis-2 showed the different in the 3'UTR features of mRNA and gene expression patterns. AUUUA-motif-containing ARE was found in mRNA of EmPis-1, but not in that of EmPis-2. EmPis-1 and EmPis-2 expressed not only in the potential sites of pathogen entry, but also in grouper's immune-related tissues such as head kidney (HD), peripheral blood leukocytes (PBL) and spleen. The expression level of EmPis-1 was higher than that of EmPis-2 in most fish tissues. Expression of both EmPis-1 and EmPis-2 were upregulated by V. parahaemolyticus significantly in the PBL, HD and spleen. Besides, expression of EmPis-1 was upregulated in gills. The putative mature peptides of EmPis-1 and EmPis-2, which were predicted to adopt an amphipathic α-helical conformation, posessed excellent microbicidal activities against both gram-negative and -positive bacteria. The hemolytic activity of the putative mature peptides of EmPis-1 and EmPis-2 increased in a dose-dependent manner to both grouper erythrocytes and rabbit erythrocytes. Interestingly, grouper erythrocytes were less vulnerable than rabbit erythrocytes to the peptides. Grouper piscidins excluded the signal peptide were not the inactive precursors but possessed high microbicidal activity evidenced by minimum bactericidal concentration (MBC) assay and by the scanning electron microscope (SEM) observation. The present phylogenetic analysis did not support the suggestion that piscidins are ancient AMPs widespread across invertebrate and vertebrate taxa, and that piscidins are included in the cecropin superfamily. Collectively, the present data improve our understanding of the piscidin family, and give greater insights into EmPis-1 and EmPis-2 of the grouper immune system.

Phytochemical characterization, antimicrobial activity and reducing potential of seed oil, latex, machine oil and presscake of Jatropha curcas

OBJECTIVE

This study aims to evaluate the antimicrobial activity, phytochemical studies and thin layer chromatography analysis of machine oil, hexane extract of seed oil and methanol extract of presscake & latex of Jatropha curcas Linn (family Euphorbiaceae).

MATERIALS AND METHODS

J. curcas extracts were subjected to preliminary qualitative phytochemical screening to detect the major phytochemicals followed by its reducing power and content of phenol and flavonoids in different fractions. Thin layer chromatography was also performed using different solvent systems for the analysis of a number of constituents in the plant extracts. Antimicrobial activity was evaluated by the disc diffusion method, while the minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration were calculated by micro dilution method.

RESULTS

The methanolic fraction of latex and cake exhibited marked antifungal and antibacterial activities against Gram-positive and Gram-negative bacteria. Phytochemical analysis revealed the presence of alkaloids, saponins, tannins, terpenoids, steroids, glycosides, phenols and flavonoids. Reducing power showed dose dependent increase in concentration compared to standard Quercetin. Furthermore, this study recommended the isolation and separation of bioactive compounds responsible for the antibacterial activity which would be done by using different chromatographic methods such as high-performance liquid chromatography (HPLC), GC-MS etc.

CONCLUSION

The results of the above study suggest that all parts of the plants possess potent antibacterial activity. Hence, it is important to isolate the active principles for further testing of antimicrobial and other biological efficacy.

In vitro control of Staphylococcus aureus (NCTC 6571) and Escherichia coli (ATCC 25922) by Ricinus communis L

OBJECTIVE

To evaluate antibacterial activity of hot and cold ethanol and methanol leaf extracts of Ricinus communis L (R. communis) against Staphylococcus aureus (S. aureus) (NCTC 6571) and Escherichia coli (E. coli) (ATCC 25922).

METHODS

Leaf powder of R. communis L. was extracted with hot (in Soxhlet) and cold ethanol and methanol, separately. The antibacterial activity of the extracts was determined by agar well diffusion and macro broth dilution methods. The extracts were also subjected to phytochemical analysis.

RESULTS

All the four test extracts showed inhibition on both S. aureus and E. coli. Hot and cold ethanol extracts revealed significantly (P<0.05) higher inhibition on S. aureus than methanol extracts, and the hot ethanol extract had the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values (5 mg/mL and 10 mg/mL, respectively). E. coli was highly inhibited by hot extracts of both ethanol and methanol with the MIC and MBC of 40 mg/mL and 80 mg/mL, respectively. Phytochemical analysis revealed the presence of saponins, cardiac glycosides, tannins, flavonoids and terpenoids in all test extracts.

CONCLUSIONS

This study demonstrates that the hot and cold methanol and ethanol extracts are potential sources for control of S. aureus and E. coli. Especially, the hot and cold extracts of ethanol are more inhibitive against S. aureus even at lower concentration. Further study is needed to identify the specific bioactive compounds, their mode of action and their nontoxic nature in vivo condition.

In vitro bacteriostatic activity of Qingre Huashi Shuwei formula and its hot-cold drug combinations against Helicobacter pylori

AIM: To compare the in vitro bacteriostatic activity of Qingre Huashi Shuwei formula and its hot-cold drug combinations against Helicobacter pylori (H. pylori).

METHODS: The minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Qingre Huashi Shuwei formula and its hot-cold drug combinations against H. pylori were determined using agar diffusion method and dilution method.

RESULTS: The bacterostasis circle diameters of Qingre Huashi Shuwei formula, hot drug group, cold drug group, and antibiotics were 14.30 mm ± 1.12 mm, 3.13 mm ± 0.82 mm, 13.93 mm ± 0.95 mm, and 23.25 mm ± 1.33 mm, respectively. The MIC of Qingre Huashi Shuwei formula was 7.81 mg/mL, and the MBC was 15.63 mg/mL.

CONCLUSION: Qingre Huashi Shuwei formula and its cold drug combination perform better in terms of in vitro bacteriostatic activity against H. pylori, and the bacteriostatic activity of Qingre Huashi Shuwei formula against H. pylori mostly comes from its cold drugs.

[In vitro activity of ceftaroline against Spanish isolates of Staphylococcus aureus: a multicenter study]

INTRODUCTION

Ceftaroline fosamil is a new-generation antimicrobial agent of cephalosporins subgroup. It is the first commercially available beta-lactam antibiotic that exhibits activity against methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study is to determine the in vitro Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of ceftaroline against S.aureus strains (including MRSA).

MATERIAL AND METHODS

A multicenter study involving four hospitals representative of the Spanish geography was performed. MIC and MBC values against both the methicillin-resistant and sensitive strains of S.aureus (MRSA and methicillin-sensitive S.aureus [MSSA]) were determined using a broth microdilution method.

RESULTS

A total of 266 S.aureus strains were analyzed (95 MRSA and 171 MSSA). Ceftaroline bacterial sensitivity showed a mean MIC of 0.227 μg/ml (SD=0.146; range, 0.06 to 1 μg/ml). All MIC values of the 266 strains tested belonged to the sensitive category (value ≤ 1 μg/ml). Intermediate or resistant strains were not detected. MIC50 and MIC90 values for MRSA were 0.25 and 0.5 μg/ml, respectively (range=0.125-1 μg/ml). MSSA strains showed MIC50 and MIC90 values of 0.125 and 0.25 μg/ml, respectively (range=0.125-0.5 μg/ml). MBC50 and MBC90 values for MRSA were 0.5 and 1 μg/ml, respectively (range=0.125-1 μg/ml). MSSA strains showed MBC50 and MBC90 values of 0.25 and 0.25 μg/ml, respectively (range=0.125-0.5 μg/ml).

CONCLUSION

Ceftaroline shows excellent in vitro activity against S.aureus, including MRSA strains. Therefore, this antibiotic may be a promising alternative for the treatment of infections caused by this bacterium.

Effects of clofazimine on planktonic and biofilm growth of Mycobacterium tuberculosis and Mycobacterium smegmatis

Mycobacteria form lipid-rich biofilms that restrict the efficacy of antimicrobial chemotherapy, possibly necessitating the use of lipophilic antibiotics. In the current study, the activity of one such agent, clofazimine, against Mycobacterium tuberculosis and Mycobacterium smegmatis planktonic cells and biofilms was investigated. Minimum inhibitory concentrations (MICs) of clofazimine were determined for planktonic cultures, whilst minimum bactericidal concentrations (MBCs) were determined for planktonic, biofilm-producing and biofilm-encased organisms using standard bacteriological procedures. The effects of clofazimine on biofilm formation and the stability of pre-formed biofilm were measured using a crystal violet-based spectrophotometric procedure. In the case of M. smegmatis, clofazimine was found to be active against planktonic phase (MICs and MBCs of 2.5mg/L and >20mg/L, respectively) and biofilm-producing organisms (MBC of 2.5mg/L); clofazimine demonstrated greater activity against M. tuberculosis, corresponding values of 0.06, 5 and 0.3mg/L. Although clofazimine inhibited biofilm production both by M. tuberculosis and M. smegmatis (P<0.05 at ≥0.07mg/L and ≥0.3mg/L, respectively) and appeared to reduce the pre-formed M. tuberculosis biofilm, addition of antimicrobial agent to pre-existing biofilm matrices failed to kill biofilm-encased organisms. In conclusion, clofazimine is more effective against M. tuberculosis than against M. smegmatis, exhibiting bactericidal activity both for actively growing and slowly replicating bacilli but not for non-replicating organisms of both species.

In-vitro activity of polyhexanide alone and in combination with antibiotics against Staphylococcus aureus

BACKGROUND

The resistance of Staphylococcus aureus is increasing, not only to antibiotics but also to antiseptics.

AIM

To investigate the activity of the antiseptic polyhexanide and several antibiotics against clinical isolates of meticillin-susceptible and meticillin-resistant Staphylococcus aureus (MSSA and MRSA, respectively). Polyhexanide was tested alone and in combination with oxacillin, penicillin G, ampicillin, cefazolin, cefuroxime, imipenem, gentamicin, erythromycin, doxycycline, levoflocaxin, linezolid and vancomycin.

METHODS

Fifty MSSA and 50 MRSA strains, including one vancomycin-intermediate (VISA) strain, were tested. All strains were typed by pulsed-field gel electrophoresis (PFGE) to exclude testing of clonal isolates. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined using the serial broth microdilution technique according to DIN 58940. Combinations of polyhexanide and different antibiotics were investigated using the checkerboard technique.

FINDINGS

Polyhexanide MICs and MBCs in the range of 0.5-2mg/L were found for both MSSA and MRSA, and the VISA strain had MIC and MBC values of 2mg/L. All isolates were regarded as susceptible to polyhexanide, and no antagonism was observed between polyhexanide and the tested antibiotics. Synergism between polyhexanide and some bacteriostatic antibiotics (erythromycin, doxycycline and linezolid) was found for some strains.

CONCLUSIONS

Polyhexanide appears to be suitable for the topical treatment of S. aureus alone and in combination with antibiotics.

Combined antibacterial activity of stingless bee (Apis mellipodae) honey and garlic (Allium sativum) extracts against standard and clinical pathogenic bacteria

OBJECTIVE

To investigate the synergic antibacterial activity of garlic and tazma honey against standard and clinical pathogenic bacteria.

METHODS

Antimicrobial activity of tazma honey, garlic and mixture of them against pathogenic bacteria were determined. Chloramphenicol and water were used as positive and negative controls, respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration of antimicrobial samples were determined using standard methods.

RESULTS

Inhibition zone of mixture of garlic and tazma honey against all tested pathogens was significantly (P≤0.05) greater than garlic and tazma honey alone. The diameter zone of inhibition ranged from (18±1) to (35±1) mm for mixture of garlic and tazma honey, (12±1) to (20±1) mm for tazma honey and (14±1) to (22±1) mm for garlic as compared with (10±1) to (30±1) mm for chloramphenicol. The combination of garlic and tazma honey (30-35 mm) was more significantly (P≤0.05) effective against Salmonella (NCTC 8385), Staphylococcus aureus (ATCC 25923), Lyesria moncytogenes (ATCC 19116) and Streptococcus pneumonia (ATCC 63). Results also showed considerable antimicrobial activity of garlic and tazma honey. MIC of mixture of garlic and tazma honey at 6.25% against total test bacteria was 88.9%. MIC of mixture of garlic and tazma honey at 6.25% against Gram positive and negative were 100% and 83.33%, respectively. The bactericidal activities of garlic, tazma honey, and mixture of garlic and tazma honey against all pathogenic bacteria at 6.25% concentration were 66.6%, 55.6% and 55.6%, respectively.

CONCLUSIONS

This finding strongly supports the claim of the local community to use the combination of tazma honey and garlic for the treatment of different pathogenic bacterial infections. Therefore, garlic in combination with tazma honey can serve as an alternative natural antimicrobial drug for the treatment of pathogenic bacterial infections. Further in vivo study is recommended to come up with a comprehensive conclusion.

Antimicrobial activity and phytochemical analyses of Polygonum aviculare L. (Polygonaceae), naturally growing in Egypt

Polygonum aviculare (Polygonaceae) is an herb commonly distributed in Mediterranean coastal regions in Egypt and used in folkloric medicine. Organic and aqueous solvent extracts and fractions of P. aviculare were investigated for antimicrobial activities on several microorganisms including bacteria and fungi. Phytochemical constituents of air-dried powered plant parts were extracted using aqueous and organic solvents (acetone, ethanol, chloroform and water). Antimicrobial activity of the concentrated extracts was evaluated by determination of the diameter of inhibition zone against both Gram-negative and Gram-positive bacteria and fungi using paper disc diffusion method. Results of the phytochemical studies revealed the presence of tannins, saponins, flavonoids, alkaloids and sesquiterpenes and the extracts were active against both Gram-negative and Gram-positive bacteria. Chloroform extract gave very good and excellent antimicrobial activity against all tested bacteria and good activity against all tested fungi except Candida albicans. Structural spectroscopic analysis that was carried out on the active substances in the chloroform extract led to the identification of panicudine (6-hydroxy-11-deoxy-13 dehydrohetisane). Evaluation of the antimicrobial activity of panicudine indicated significant activity against all tested Gram-negative and Gram-positive organisms. Panicudine displayed considerable activity against the tested fungi with the exception of C. albicans. Antimicrobial activity of the extracts was unaffected after exposure to different heat treatments, but was reduced at alkaline pH. Studies of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of panicudine on the tested organisms showed that the lowest MIC and the MBC were demonstrated against Salmonella paratyphi, Bacillus subtilis and Salmonella typhi and the highest MIC and MBC were against Staphylococcus aureus.

Activity of the antiseptic polyhexanide against meticillin-susceptible and meticillin-resistant Staphylococcus aureus

Staphylococcus aureus is one of the most important pathogens, with increasing emergence of meticillin-resistant S. aureus (MRSA) strains. This is associated not only with multiresistance to antibiotics but also with increasing resistance to topical antibiotics and antiseptics. As the antiseptic polyhexanide has only a low risk of emergence of resistant strains, the aim of the study was to obtain data on the sensitivity of S. aureus towards polyhexanide. The effect of polyhexanide was tested against 80 meticillin-susceptible S. aureus (MSSA) and 80 MRSA strains from sporadic cases as well as against 6 MRSA outbreak strains. The clonal diversity of the 166 strains was proven by pulsed-field gel electrophoresis (PFGE). Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by the serial broth microdilution technique according to DIN 58940. Time-kill studies were performed for reference strains MSSA ATCC 29213 and MRSA ATCC 33591. MICs and MBCs in the range of 0.5-2mg/L were found. According to a created epidemiological cut-off (ECOFF) value of 4mg/L, all strains were regarded as susceptible to polyhexanide, including MRSA epidemic strains and MSSA and MRSA sporadic strains with various antibiotic susceptibility patterns. Addition of up to 4% albumin to the test medium did not change the MICs and MBCs. Time-kill studies showed reduction rates of 4log₁₀CFU/mL for 200mg/L and 5log₁₀CFU/mL for 400mg/L polyhexanide within 5-30min. It is concluded that polyhexanide is suitable for topical eradication of S. aureus.

Antimicrobial potential of Terminalia chebula Retz. fruit extracts against ear pathogens

AIM: To evaluate the antimicrobial potential of Terminalia chebula (T. chebula) extracts against pathogens causing otitis externa and compare it with ear drops.

METHODS: Four different extracts, methanol, ethanol, acetone and aqueous (hot and cold) extracts, from the T. chebula were tested for their antimicrobial activity through the agar well diffusion method and minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) values were determined through the macrodilution broth method against six different microorganism, five bacterial (one gram positive and four gram negative) and one yeast.

RESULTS: Organic and aqueous fruit extracts displayed activity against all five tested bacterial ear pathogens with a maximum zone of inhibition of 31.6 mm against Staphylococcus aureus, followed by Acinetobacter sp. (24.6 mm), Pseudomonas aeruginosa (23.6 mm), Proteus mirabilis (21 mm) and Escherichia coli (19.3 mm). Of the four solvents evaluated, acetonic fruit extract of T. chebula was found to be best. The MIC values ranged between 0.78 mg/mL and 50 mg/mL for the different bacterial ear pathogens and MBC values ranged between 1.56 mg/mL and 50 mg/mL. The acetonic fruit extract showed larger inhibition zones compared to the herbal ear drops, Kan pip with lowest MIC of 0.78 mg/mL and MBC of 1.56 mg/mL.

CONCLUSION: Acetonic extract of T. chebula fruit may be used to treat otitis externa. However, more detailed studies, such as in vivo testing and pharmacokinetics properties, are needed to determine its therapeutic potential.