scholarly journals Benzalkonium Chloride Induces a VBNC State in Listeria monocytogenes

2020 ◽  
Vol 8 (2) ◽  
pp. 184
Author(s):  
Matthias Noll ◽  
Katharina Trunzer ◽  
Antje Vondran ◽  
Szilvia Vincze ◽  
Ralf Dieckmann ◽  
...  
Keyword(s):  
Health Risks ◽  
Benzalkonium Chloride ◽  
Antimicrobial Agents ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Cell Membrane Permeability ◽  
Bacterial Cells ◽  
Vbnc State ◽  
Colony Forming Units ◽  
Sublethal Concentrations

The objective of our study was to investigate the effects of benzalkonium chloride (BC) adaptation of L. monocytogenes on the susceptibility to antimicrobial agents and on the viable but non culturable (VBNC) state of the bacterial cells. We adapted L. monocytogenes SLCC2540 to BC by applying BC below minimum inhibitory concentration (MIC) to above minimum bactericidal concentration (MBC). The culturable fractions and the susceptibility of adapted and parental cells to BC were assessed. In addition, cell membrane permeability and glucose uptake were analyzed by multi parametric flow cytometry using the fluorescent agents SYTO9, propidium iodide, and 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose (2-NBDG). Adapted cells displayed a two-fold MIC increase of BC and reduced antibiotic susceptibility. At high BC concentrations, the decrease in the number of colony forming units was significantly lower in the population of adapted cells compared to parental cells. At the same time, the number of metabolically active cells with intact membranes was significantly higher than the number of culturable cells. Growth-independent viability assays revealed an adapted subpopulation after BC application that was not culturable, indicating increased abundance of viable but nonculturable (VBNC) cells. Moreover, adapted cells can outcompete non-adapted cells under sublethal concentrations of disinfectants, which may lead to novel public health risks.

scholarly journals Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) for Twelve Antimicrobials (Biocides and Antibiotics) in Eight Strains of Listeria monocytogenes

Biology ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 46
Author(s):  
Cristina Rodríguez-Melcón ◽  
Carlos Alonso-Calleja ◽  
Camino García-Fernández ◽  
Javier Carballo ◽  
Rosa Capita
Keyword(s):  
Antibiotic Resistance ◽  
Listeria Monocytogenes ◽  
Benzalkonium Chloride ◽  
Species Differences ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Surface Characteristics ◽  
Bacterial Cells ◽  
High Prevalence ◽  
Effective Doses

When selecting effective doses of antimicrobials, be they biocides or antibiotics, it is essential to know the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of these substances. The present research determined the MICs and MBCs for three biocides, sodium hypochlorite (SH), benzalkonium chloride (BC), and peracetic acid (PAA), and nine antibiotics in eight strains of Listeria monocytogenes of varying serotypes. Marked intra-species differences were observed in the resistance of L. monocytogenes to the biocides and antibiotics. The MICs (ppm) for the biocides ranged between 1750 and 4500 for SH, 0.25 and 20.00 for BC, and 1050 and 1700 for PAA. Their MBCs (ppm) ranged from 2250 to 4500 for SH, 0.50 to 20.00 for BC, and 1150 to 1800 for PAA. The MICs (ppm) for antibiotics lay between 1 and 15 for ampicillin, 8 and 150 for cephalothin, 20 and 170 for cefoxitin, 0.05 and 0.20 for erythromycin, 4 and 50 for chloramphenicol, 3 and 100 for gentamicin, 2 and 15 for tetracycline, 2 and 80 for vancomycin, and 160 and 430 for fosfomycin. The corresponding MBCs (ppm) were from 5 to 20 for ampicillin, 9 to 160 for cephalothin, 70 to 200 for cefoxitin, 4 to 5 for erythromycin, 9 to 70 for chloramphenicol, 5 to 100 for gentamicin, 3 to 30 for tetracycline, 3 to 90 for vancomycin, and 160 to 450 for fosfomycin. Notably, erythromycin showed considerable efficacy, demonstrated by the low values for both MIC and MBC. Based on EUCAST and the CLSI criteria, all strains were susceptible to erythromycin. All strains were resistant to cephalothin, cefoxitin, gentamicin, and fosfomycin. Further values for resistance were 87.50% for ampicillin and vancomycin, 75.00% for tetracycline, and 62.50% for chloramphenicol. The high prevalence of antibiotic resistance is a matter for concern. A positive correlation was found between MIC and MBC values for most of the biocides and antibiotics. The higher the hydrophobicity of the cell surface, the higher the susceptibility to biocides, suggesting that surface characteristics of bacterial cells influence resistance to these compounds.

scholarly journals THE EFFECT OF PROPOLIS EXTRACT AND PROPOLIS CANDIES ON THE GROWTH OF AGGREGATIBACTER ACTINOMYCETEMCOMITANS ATCC 43718

2017 ◽  
Vol 10 (17) ◽  
pp. 26
Author(s):  
Khodijah Khodijah ◽  
Ratna Farida ◽  
Nurtami Soedarsono
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Spectrophotometric Analysis ◽  
Propolis Extract ◽  
Post Exposure ◽  
Colony Forming Units

Objective: This experiment aimed to analyze the effect of propolis extract and propolis containing candies on the growth of Aggregatibacter actinomycetemcomitans using spectrophotometric analysis and colony-forming units (CFU) counts.Methods: After A. actinomycetemcomitans were exposed to propolis extract and candies, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined with spectrophotometry and post-exposure colony counting.Results: The MIC of propolis extract against A. actinomycetemcomitans was determined to be 10%, and the MBC was 20%. A decrease in the total CFU count of A. actinomycetemcomitans was observed after propolis extract and candy exposure.Conclusions: Propolis extract and propolis candies were effective in inhibiting the growth of A. actinomycetemcomitans ATCC 43718 in vitro.

scholarly journals Effects of biocide exposure on P. Aeruginosa, E. coli and A. Baumannii complex isolates from hospital and household environments

Infectio ◽  
2017 ◽  
Vol 21 (4) ◽  
Author(s):  
Daniel Felipe Vásquez-Giraldo ◽  
Gerardo Andrés Libreros-Zúñiga ◽  
María Del Pilar Crespo-Ortiz
Keyword(s):  
Escherichia Coli ◽  
Benzalkonium Chloride ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Multidrug Resistant ◽  
Environmental Isolates ◽  
E Coli ◽  
Acinetobacter Baumannii Complex ◽  
Cleaning And Disinfection ◽  
Reference Strains

Background: Bacterial responses to biocide exposure and its effects on survival and persistence remain to be studied in greater detail.Aim: To analyse the viability and survival of environmental isolates from household and hospital settings after biocide exposure.Methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of chlorhexidine (CHxG), benzalkonium chloride (BAC) and triclosan (TC) were determined in isolates of Pseudomonas aeruginosa, Acinetobacter baumannii complex and Escherichia coli collected from hospital and households environments. Viability was monitored after exposure and removal of biocides using agar cultures and flow cytometry.Findings: P. aeruginosa isolates showed greater tolerance for all biocides tested whereas A. baumannii complex and E. coli were less tolerant.When compared with reference strains, biocide tolerance was up to 8 to 13-fold higher for TC and BAC respectively. Flow cytometry showed that biocide exposure may induce viable but non-growing states in P. aeruginosa and E. coli isolates before becoming fully replicative. Changes in the susceptibility profile in one isolate of A. baumannii complex were observed after biocide exposure.Discussion: Bacteria isolates from hospital and households were able to recover after biocide exposure at bactericidal concentrations favouring persistence and spread of biocide-tolerant strains. This study reinforces that cleaning compliance should be monitored by non-culture based tests. Novel formulations in cleaning and disinfection protocols should be revisited in hospitals harbouring P. aeruginosa and A. baumannii multidrug resistant isolates.

scholarly journals Antibacterial Activity of Lupinifolin from Derris reticulata and Its Effect on Cytoplasmic Membrane of Methicillin Resistant

2020 ◽  
Vol 17 (10) ◽  
pp. 1104-1112
Author(s):  
Kamol YUSOOK ◽  
Pettaya PANVONGSA
Keyword(s):  
Propidium Iodide ◽  
Nmr Spectra ◽  
Inhibitory Concentration ◽  
Cytoplasmic Membrane ◽  
Minimum Bactericidal Concentration ◽  
Membrane Integrity ◽  
Bacterial Cells ◽  
Liquid Chromatography Mass Spectrometry ◽  
Methicillin Resistant ◽  
Derris Reticulata

Lupinifolin from Derris reticulata Craib. was extracted with hexane by Soxhlet extractor and purified by crystallization. The yellow needle-shaped lupinifolin crystals were identified and confirmed by nuclear magnetic resonance (NMR) spectra and Liquid chromatography mass spectrometry (LC/MS). The lupinifolin showed minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 8 and 16 µg/ml against Methicillin resistant S. aureus (MRSA), respectively. The flow cytometry (FCM) was performed to determine the alteration of cytoplasmic membrane (CM) permeability of MRSA by using Propidium iodide (PI) 5 µg/ml as an indicator for bacterial membrane integrity. It was found that the bacterial CM permeability was effected by lupinifolin with the MIC of 8 µg/ml comparable to the control when investigated by Propidium iodide intensity. Additionally, DNA laddering assay was carried out to evaluate apoptosis in bacterial cells. It was shown that the lupinifolin has no effect on DNA fragmentation.

scholarly journals Antimicrobial activity of Lippia sidoides Cham. (Verbenaceae) essential oil against Staphylococcus aureus and Escherichia coli

2011 ◽  
Vol 13 (3) ◽  
pp. 293-297 ◽  
Author(s):  
C.E Castro ◽  
J.M Ribeiro ◽  
T.T Diniz ◽  
A.C Almeida ◽  
L.C Ferreira ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Essential Oil ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Antibacterial Effect ◽  
Bactericidal Effect ◽  
Bacterial Cells ◽  
E Coli ◽  
Lippia Sidoides

The antibacterial effect of Lippia sidoides (rosemary pepper) essential oil was tested against the bacteria Staphylococcus aureus and Escherichia coli isolated from homemade Minas cheese produced in Brazil. The Minimum Inhibitory Concentration (MIC) determined in the Dilution Test was 13 µL oil mL-1 for both bacteria, which characterizes inhibitory action in broth for a 24-hour interaction period. The Minimum Bactericidal Concentration (MBC) determined in the Suspension Test, with one minute of contact, was 25 µL oil mL-1 for both tested bacteria, obtaining at this concentration a bactericidal effect of 99.9% on the viable bacterial cells from each sample. Results demonstrated the bacterial activity of Lippia sidoides essential oil against S. aureus and E. coli, suggesting its use as an antibacterial agent in foods.

scholarly journals Down-regulation of biofilm-associated genes in mecA-positive methicillin-resistant S. aureus treated with M. communis extract and its antibacterial activity

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Moj Khaleghi ◽  
Sadegh Khorrami
Keyword(s):  
Biofilm Formation ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Ethanolic Extract ◽  
Multidrug Resistant ◽  
Clinical Samples ◽  
Bacterial Cells ◽  
Methicillin Resistant ◽  
Different Strains ◽  
Biofilm Development

AbstractConsidering the prevalence of resistance to antibiotics, the discovery of effective agents against resistant pathogens is of extreme urgency. Herein, 26 mecA-positive methicillin-resistant S. aureus (MRSA) isolated from clinical samples were identified, and their resistance to 11 antibiotics was investigated. Next, the antibacterial and anti-biofilm activity of the ethanolic extract of M. communis on these strains was evaluated. Furthermore, the effect of this extract on the expression of biofilm-associated genes, icaA, icaD, bap, sarA, and agr, was studied. According to the results, all isolated strains were multidrug-resistant and showed resistance to oxacillin and tetracycline. Also, 96.15 and 88.46 % of them were resistant to gentamicin and erythromycin. However, the extract could effectively combat the strains. The minimum inhibitory concentration (MIC) against different strains ranged from 1.56 to 25 mg/ml and the minimum bactericidal concentration (MBC) was between 3.125 and 50 mg/ml. Even though most MRSA (67 %) strongly produced biofilm, the sub-MIC concentration of the extract destroyed the pre-formed biofilm and affected the bacterial cells inside the biofilm. It could also inhibit biofilm development by significantly decreasing the expression of icaA, icaD, sarA and bap genes involved in biofilm formation and development. In conclusion, the extract inhibits biofilm formation, ruins pre-formed biofilm, and kills cells living inside the biofilm. Furthermore, it down-regulates the expression of necessary genes and nips the biofilm formation in the bud.

Homologous and heterologous adaptation and thermochemical inactivation of Staphylococcus aureus to cinnamaldehyde

2020 ◽  
Author(s):  
Luciana Vitorino ◽  
Tenille Ribeiro de Souza ◽  
Michelle Carlota Gonçalves ◽  
Letícia Andrade do Vale ◽  
Roberta Hilsdorf Piccoli
Keyword(s):  
Staphylococcus Aureus ◽  
Exposure Time ◽  
Antimicrobial Agents ◽  
Acid Stress ◽  
Bactericidal Effect ◽  
Adaptive Plasticity ◽  
Bacterial Cells ◽  
Positive Effect ◽  
Sublethal Concentrations ◽  
Antibacterial Potential

Staphylococcus aureus causes food intoxication and can become resistant to a large number of drugs. Thus, there is a growing interest in understanding the mechanisms involved in the adaptation of bacterial cells to environmental stresses or to antimicrobial agents. In this context, we evaluated the cinnamaldehyde (CIN) MBC for two contaminating food strains of S. aureus (GL 5674 and GL 8702) and tested the hypothesis that the exposure of these strains to sublethal concentrations of CIN and pH could increase their resistance to this antimicrobial, to acid stress and also to stress at high temperatures. Thus, the ability of the strains to adapt to CIN and acid stress was evaluated, as well as the cross adaptation between acid stress and CIN. The strains GL 5674 and GL 8702 of S. aureus are sensitive to CIN in MBCs of 0.25% and 0.5% respectively, proving the antibacterial potential of this compound, but we proved the hypothesis of homologous adaptation to CIN. The strains grew in concentrations higher than the MBC after being previously exposed to sublethal concentrations of CIN. It was also observed heterologous adaptation of the strains, which, after exposure to the minimum pH of growth, were able to grow in concentrations greater than the MBC of CIN. GL 5674 showed greater adaptive plasticity, considerably reducing its minimum inhibitory pH and increasing its MBC after adaptation. Our results show a positive effect of adaptation to CIN, on the resistance of S. aureus (p <0.0001) to CIN, at a temperature of 37 ° C. However, in the absence of adaptation, the presence of CIN in S. aureus cultures maintained at 37 ° C, associated with increased exposure time showed an efficient bactericidal effect. Our results call attention to the conscious use of CIN as an antimicrobial agent and presents the possibility of using CIN, associated with the temperature of 37 ºC and the exposure time of 35 min, as a promising measure for the elimination of pathogenic strains .

Effect of piperacillin on morphology and viability of gram-negative bacteria

1984 ◽  
Vol 42 ◽  
pp. 218-219
Author(s):  
R. H. Liss
Keyword(s):  
Inhibitory Concentration ◽  
Cytoplasmic Membrane ◽  
Drug Binding ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Drug Induced ◽  
Penicillin Binding Proteins ◽  
Lactam Antibiotic ◽  
Drug Free ◽  
Tube Dilution

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.

Green and Simple Synthesis of Silver Nanoparticles by Aqueous Extract of Perovskia abrotanoides: Characterization, Optimization and Antimicrobial Activity

2020 ◽  
Vol 21 (11) ◽  
pp. 1129-1137 ◽  
Author(s):  
Somayeh Mirsadeghi ◽  
Masoumeh F. Koudehi ◽  
Hamid R. Rajabi ◽  
Seied M. Pourmortazavi
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Minimum Inhibitory Concentration ◽  
Plant Extract ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Extraction Temperature ◽  
Silver Particles ◽  
Silver Nps ◽  
Perovskia Abrotanoides

Background: Herein, we report the biosynthesis procedure to prepare silver nanoparticles as reduction and capping agents with the aqueous plant extract of Perovskia abrotanoides. Methods: The therapeutic application of silver nanoparticles entirely depends on the size and shape of the nanoparticles therefore, their control during the synthesis procedure is so important. The effects of synthesis factors, for example, silver ion concentration, the mass of plant extract, reaction time and extraction temperature, on the size of silver particles were considered and optimized. Several analytical methods were used for the characterization of silver NPs including FT-IR and UV–Vis spectrophotometer, XRD and SEM. Results: The results showed that the mean size of the silver particles was about 51 nm. Moreover, the antibacterial properties of biosynthesized silver NPs were investigated by the minimum inhibitory concentration, minimum bactericidal concentration, and Well-diffusion tests. The minimum inhibitory concentration/ minimum bactericidal concentration values of silver NPs and aqueous plant extract versus Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and Gram-negative bacteria (E. coli) were 3.03/0.00, 1.20/0.01, 3.06/0.00, 0.98/1.04, 1.00/0.05 and 1.30/0.03 (mg/mL), respectively. Conclusion: The antimicrobial activity study displayed that the synthesized silver nanoparticles by plant extract have better antimicrobial properties compared to aqueous plant extract of Perovskia abrotanoides.

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