scispace - formally typeset
Search or ask a question
Topic

Minimum bactericidal concentration

About: Minimum bactericidal concentration is a research topic. Over the lifetime, 4461 publications have been published within this topic receiving 100857 citations. The topic is also known as: MBC.


Papers
More filters
Journal ArticleDOI
TL;DR: Apigenin is a novel and potent inhibitor of GTF activity, and tt-farnesol was found to be an effective antibacterial agent.
Abstract: Propolis, a resinous bee product, has been shown to inhibit the growth of oral microorganisms and the activity of bacterium-derived glucosyltransferases (GTFs). Several compounds, mainly polyphenolics, have been identified in this natural product. The present study evaluated the effects of distinct chemical groups found in propolis on the activity of GTF enzymes in solution and on the surface of saliva-coated hydroxyapatite (sHA) beads. Thirty compounds, including flavonoids, cinnamic acid derivatives, and terpenoids, were tested for the ability to inhibit GTFs B, C, and D from Streptococcus mutans and GTF from S. sanguinis (GTF Ss). Flavones and flavonols were potent inhibitors of GTF activity in solution; lesser effects were noted on insolubilized enzymes. Apigenin, a 4',5,7-trihydroxyflavone, was the most effective inhibitor of GTFs, both in solution (90.5 to 95% inhibition at a concentration of 135 microg/ml) and on the surface of sHA beads (30 to 60% at 135 microg/ml). Antibacterial activity was determined by using MICs, minimum bactericidal concentrations (MBCs), and time-kill studies. Flavanones and some dihydroflavonols, as well as the sesquiterpene tt-farnesol, inhibited the growth of S. mutans and S. sobrinus; tt-farnesol was the most effective antibacterial compound (MICs of 14 to 28 microg/ml and MBCs of 56 to 112 microg/ml). tt-Farnesol (56 to 112 microg/ml) produced a 3-log-fold reduction in the bacterial population after 4 h of incubation. Cinnamic acid derivatives had negligible biological activities. Several of the compounds identified in propolis inhibit GTF activities and bacterial growth. Apigenin is a novel and potent inhibitor of GTF activity, and tt-farnesol was found to be an effective antibacterial agent.

329 citations

Journal ArticleDOI
TL;DR: The objective is to isolate the biologically active fraction of the lipopeptide biosurfactant produced by a marine Bacillus circulans and study its antimicrobial potentials.
Abstract: Aims: To isolate the biologically active fraction of the lipopeptide biosurfactant produced by a marine Bacillus circulans and study its antimicrobial potentials. Methods and Results: The marine isolate B. circulans was cultivated in glucose mineral salts medium and the crude biosurfactant was isolated by chemical isolation method. The crude biosurfactants were solvent extracted with methanol and the methanol extract was subjected to reverse phase high-performance liquid chromatography (HPLC). The crude biosurfactants resolved into six major fractions in HPLC. The sixth HPLC fraction eluting at a retention time of 27·3 min showed the maximum surface tension-reducing property and reduced the surface tension of water from 72 mNm−1 to 28 mNm−1. Only this fraction was found to posses bioactivity and showed a pronounced antimicrobial action against a panel of Gram-positive and Gram-negative pathogenic and semi-pathogenic micro-organisms including a few multidrug-resistant (MDR) pathogenic clinical isolates. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of this antimicrobial fraction of the biosurfactant were determined for these test organisms. The biosurfactant was found to be active against Gram-negative bacteria such as Proteus vulgaris and Alcaligens faecalis at a concentration as low as 10 μg ml−1. The biosurfactant was also active against methicillin-resistant Staphylococcus aureus (MRSA) and other MDR pathogenic strains. The chemical identity of this bioactive biosurfactant fraction was determined by post chromatographic detection using thin layer chromatography (TLC) and also by Fourier transform infrared (FTIR) spectroscopy. The antimicrobial HPLC fraction resolved as a single spot on TLC and showed positive reaction with ninhydrin, iodine and rhodamine-B reagents, indicating its lipopeptide nature. IR absorption by this fraction also showed similar and overlapping patterns with that of other lipopeptide biosurfactants such as surfactin and lichenysin, proving this biosurfactant fraction to be a lipopeptide. The biosurfactant did not show any haemolytic activity when tested on blood agar plates, unlike the lipopeptide biosurfactant surfactin produced by Bacillus subtilis. Conclusions: The biosurfactant produced by marine B. circulans had a potent antimicrobial activity against Gram-positive and Gram-negative pathogenic and semi-pathogenic microbial strains including MDR strains. Only one of the HPLC fractions of the crude biosurfactants was responsible for its antimicrobial action. The antimicrobial lipopeptide biosurfactant fraction was also found to be nonhaemolytic in nature. Significance and impact of the study: This work presents a nonhaemolytic lipopeptide biosurfactant produced by a marine micro-organism possessing a pronounced antimicrobial action against a wide range of bacteria. There is a high demand for new antimicrobial agents because of the increased resistance shown by pathogenic micro-organisms against the existing antimicrobial drugs. This study provides an insight into the search of new bioactive molecules from marine micro-organisms.

319 citations

Journal ArticleDOI
TL;DR: Studies in different animal infection models with a variety of organisms suggest that beta-lactams are more efficacious with continuous dosing, whereas the efficacy of aminoglycosides is relatively independent of dosing regimen, even when administered once daily.

312 citations

Journal ArticleDOI
TL;DR: Mupirocin (pseudomonic acid A), an antibiotic produced by Pseudomonas fluorescens, showed a high level of activity against staphylococci and streptococciand against certain gram-negative bacteria, but was much less active against most gram- negative bacilli an anaerobes.
Abstract: Mupirocin (pseudomonic acid A), an antibiotic produced by Pseudomonas fluorescens, showed a high level of activity against staphylococci and streptococci and against certain gram-negative bacteria, including Haemophilus influenzae and Neisseria gonorrhoeae, but was much less active against most gram-negative bacilli an anaerobes. Nearly all clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis, including multiply resistant strains, were susceptible (mupirocin MIC, less than or equal to 0.5 microgram/ml). There was no cross-resistance between mupirocin and clinically available antibiotics, and the selection of resistant variants in vitro occurred at a low frequency. Mupirocin was highly bound (95% bound) to the protein of human serum, and activity was reduced 10- to 20-fold in the presence of human serum. The activity of mupirocin was not greatly influenced by inoculum size but was significantly enhanced in acid medium. In tests of bactericidal activity, MBCs were 8- to 32-fold higher than MICs and the antibiotic demonstrated a slow bactericidal action in time-kill tests, resulting in 90 to 99% killing after 24 h at 37 degrees C.

307 citations

Journal ArticleDOI
TL;DR: In this paper, four quaternary ammonium salt monomers were synthesized from dimethylaminoethyl methacrylate (DMAEMA) by quaternization with benzyl chloride (BC), butyl bromide (BB), dodecyl brameride (DB), or hexadecyl bromides (HB), respectively, and the resultant monomers and related polymers were characterized by elemental analysis, FTIR, NMR, thermogravimetric analysis (TGA).
Abstract: Four quaternary ammonium salt monomers were synthesized from dimethylaminoethyl methacrylate (DMAEMA) by quaternization with benzyl chloride (BC), butyl bromide (BB), dodecyl bromide (DB) or hexadecyl bromide (HB), respectively. And then, the monomers were homopolymerized to obtain four polymeric quaternary ammonium materials with different lengths of alkyl chain, which were referred to as poly(DMAEMA-BC), poly(DMAEMA-BB), poly(DMAEMA-DB) and poly(DMAEMA-HB), respectively. The resultant monomers and related polymers were characterized by elemental analysis, FTIR, NMR, thermogravimetric analysis (TGA) and so on. Their bactericidal activities were evaluated by determining minimum bactericidal concentration (MBC) values and inhibitory zone diameters against Gram-positive bacteria ( S. aureus ) and Gram-negative bacteria ( E. coli ), respectively. The results showed that the MBC values of monomer DMAEMA-DB and DMAEMA-HB were 12–24 μg/mL against E. coli and S. aureus . However, the MBC values of monomer DMAEMA-BC and DMAEMA-BB were higher than 50 mg/mL against test microbe. It was very interesting that poly(DMAEMA-BC) and poly(DMAEMA-BB) exhibited greater bactericidal activities than their precursory monomers, but poly(DMAEMA-DB) and poly(DMAEMA-HB) present contrary results.

302 citations


Network Information
Related Topics (5)
Antimicrobial
45.4K papers, 1M citations
92% related
Antibiotic resistance
29.1K papers, 884.5K citations
85% related
Biofilm
23K papers, 906.8K citations
84% related
Antibacterial agent
35.8K papers, 1.2M citations
83% related
Antioxidant
37.9K papers, 1.7M citations
80% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023164
2022357
2021338
2020412
2019337
2018322