NadD or NadE knockdown has strong bactericidal effects in an M. smegmatis model. A protein depletion method recently developed and validated in mycobacteria (29) allowed us to assess bactericidal effects and explore the metabolic consequences of de- pleting NadD and NadE enzymes in an M. smegmatis model sys- tem. The induction of targeted proteolysis in each of the two en- gineered strains (Fig. 2A) led to ⱖ90% degradation of NadD or NadE enzymes within the first 2 h by both Western blot and en- zymatic activity analyses (Fig. 2B and C). These effects were target specific; depletion of one target enzyme had no effect on the ac- tivity of another enzyme. Inactivation of either enzyme led to a complete growth arrest by 6 h after induction (Fig. 2D). More- over, the knockdown (KD) of either NadD or NadE had an appar- ent bactericidal effect, as evidenced by a ⬎ 1,000-fold decrease in the number of viable cells (in CFU/ml) compared to the unin- duced control whereas the drop in the overall cell number was only ⬍10-fold (Fig. 2E). A comparable bactericidal effect was ob- served upon induction of NadD or NadE degradation after incu- bation for 3 days under carbon starvation conditions (dormancy) (see Fig. S4 in the supplemental material). Taken together, these results provide the first direct validation of both the NadD and NadE enzymes as potential targets for the development of bacte- ricidal agents against mycobacteria. The relevance of this conclu- sion for M. tuberculosis is supported by the observation that the expression of the nadRh gene from M. tuberculosisin M. smegmatis did not suppress the bactericidal effect of the induced degradation of NadD or NadE enzymes even when NmR was added to the growth media (see Text S1 in the supplemental material).
How does UVB-LED irradiation elicit bactericidal ef- fects on bacteria? UV light, especially UVC light, impairs DNA to induce pyrimidine dimers and then inhibits cell proliferation, elicits apoptosis, and finally induces cell death [20, 21]. UVC light has the strongest bactericidal effects and particularly around 254 nm of UVC is absorbed mostly to DNA. In this study, we observed that 265 nm UVC-LED irradiation has a stronger bactericidal effect than that of UVB-LED irradiation. UVB irradiation also exhibits DNA damage to form pyrimidine dimers, but the effect is very low. Therefore, UVB irradiation may show low toxicity to gingival epithelial cells.
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Compared to common antibiotics, the concentrations of Berberis Decoctum D2 needed for bactericidal effects are considerably higher. Interesting for systemic usability would be a concentration <100 μg/ml for plant extracts or <10 μg/ml for isolated compounds . In an assay re- vealing the effects of Berberis Decoctum D2 on human lymphocytes we found that Berberis Decoctum D2 is in- ducing apoptosis in about 70 % of lymphocytes if applied in a concentration of 5 mg/ml (MIC results not shown). Systemic application in a bactericidal dosage of 5 mg/ml would therefore be toxic. In AM, however, the prepar- ation is injected subcutaneously, close to the infected areas, e.g. around the paranasal sinuses to treat sinusitis . This application might indeed induce brief antibac- terial concentrations in the subcutaneous tissues. It re- mains an open question, whether this is relevant for the treatment with this medication and weather it improves healing properties according to the concepts of AM.
In addition, the MBC/MIC ratio was used to determine the bactericidal or bacteriostatic different extracts. According Berche et al. , when this ratio is less than or equal to 4, the extract has a bactericidal and bacteriostatic when this ratio is greater than 4. Thus, we can say that with the exception of the aqueous extract which power could be determined up to 100 mg/mL, the other three extracts exerted bactericidal effects against all bacterial strains tested. Antibacterial activities observed are explained by the results of the phytochemical analysis of the extracts studied (Table 3) revealed the presence of compounds such as polyphenols, flavonoids, tannins, cardiac glycosides, alkaloids and sterols and polyterpenes.
Evidence suggests that Pseudomonas aeruginosa bacteria form biofilms within the airways of adults with cystic fibrosis (CF). The objective of this study was to determine whether clinical isolates of P. aeruginosa recovered from adults with CF have similar susceptibilities to individual antibiotics and to antibiotic combi- nations when grown as adherent monolayers or as biofilms compared to when they are grown using planktonic methods. Twelve multiresistant P. aeruginosa isolates, one mucoid and one nonmucoid from each of six CF patients, were grown conventionally under planktonic conditions, as adherent bacterial monolayers, and as biofilms. Each bacterial isolate remained genotypically identical despite being cultured under planktonic, adherent, or biofilm growth conditions. Isolates grown as adherent monolayers and as biofilms were less susceptible to bactericidal killing by individual antibiotics compared to those grown planktonically. More importantly, biofilm-grown bacteria, but not adherent monolayer-grown bacteria, were significantly less sus- ceptible to two- and three-drug combinations of antibiotics than were planktonically grown bacteria (P ⴝ 0.005). We conclude that biofilm-grown bacteria derived from patients with CF show decreased susceptibility to the bactericidal effects of antibiotic combinations than do adherent and planktonically grown bacteria.
and B) demonstrated no bactericidal effects on both with and without injectable self-assembled biomimetic nano- matrix gel; this reflected that MN may not be an effective antibiotic choice for facultative anaerobic bacteria . “In Figure 4B, the condition of the culture media and E. faecalis together may interact with the nanomatrix gel and affect the OD values of the experiment and this cul- ture condition will be investigated further in the future experiment.” However, MN may be the effective bacteri- cidal agent in a complex of bacteria from the root canal infection, which represents most of anaerobic bacteria. When MN encapsulated injectable self-assembled bio- mimetic nanomatrix gel was tested against T. denticola (Figure 6A and B); bactericidal effect has shown success- fully in the two lower T. denticola densities (2.0 × 10 6 CFU/mL and 2.0 × 10 7 CFU/mL). In the density of 2.0 × 10 8 CFU/mL, T. denticola did not portray complete bactericidal activity and this may be relatively low MN concentrations compare to the bacterial load.
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The bactericidal effects of every diluted “Sumerian Silver” were shown in Figure 1. The bacteria on the Petri dish around the orifice could be killed and shows trans- parent when the antibiotic was injected, otherwise it could grow and not transparent. The diameter of inhibit- tion zone also could be used to express the bactericidal effect according to Hultmark (1992). The samples of “Sumerian Silver” exhibit extremely bactericidal effects at the concentration of 10 to 50 times dilutions, but it was not obviously observed at the concentration of 400 times dilutions. The results showed that different effects of silver nanoparticles against various bacterial patho- gens of sericulture. The bactericidal zone were obviou sly when it against Bacillus spp., Bacillus thuringinsis, shamin bacterium, and Streptococcus aureus even at concentration of 1:400. The less effect was observed on the experiment of silver nanoparticles against fungal pathogen of mulberry, Aecidium mori (Barclay). Further, the least effect were detected when it against Serratia marcescens only at the concentration of 1:10.
Aztreonam (48 mg/l) had bacteriostatic effects on 43.5– 56.5% of the strains but bactericidal effects on only 0– 4.3% at 2–24 h after its addition (Table 1, Figure 1). The 3-drug combination of aztreonam (16 mg/l), ceftazidime (16 mg/l) and amikacin (4 mg/l) had bacteriostatic effects on 69.6–82.6% of the strains and bactericidal effects on 8.7–39.1% at 2–24 h after their addition (Table 2, Figure 2). On the other hand, colistin (2 mg/l) exhibited bacteri- cidal effects on all strains (100%) at 2–24 h after its addi- tion (Table 3, Figure 3). Kruskal-Wallis tests showed significant decreases in the viable cell count at 2, 4, 6 and 24 h after the addition of colistin (Figure 3) compared with aztreonam alone (Figure 1) or the 3-drug combina- tion of aztreonam, ceftazidime and amikacin (Figure 2).
Different combinations of essential oils from cinnamon, cloves, oregano, and thyme were evaluated in vitro for their bactericidal activity against entero- toxigenic Escherichia coli (ETEC). The solutions containing cinnamon (0.03%), oregano (0.16%), and thyme (0.08%) (P1); and clove (0.08%), ore- gano (0.33%), and thyme (0.04%) (P2), exhibited high bactericidal activity, and were selected for use as preservatives in ground beef inoculated with ETEC and refrigerated. The two preservative solutions (P1 and P2) exhibited significant bactericidal action (p < 0.05) on ETEC, with ETEC reductions of 1.03 and of 0.87 LogUFC/g in the beef samples treated with P1 and P2, re- spectively. GC-MS analysis of the oil mixtures showed both preservatives to contain significant concentrations of carvacrol. Chromatic degradation was not observed in the samples treated with preservatives. Essential oil mixtures thus concocted are therefore potential preservative candidates in ground beef, as they are capable of controlling ETEC contamination while preserving the products’ coloration.
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To investigate the bactericidal activity of the SDN formulations, as a surrogate for Mtb, we employed a green ﬂ uorescent protein (GFP) reporter strain of Mycobacterium avium subsp. paratuberculosis (Map K10/GFP) (Harris et al. 2002) permitting viability to be monitored using ﬂ uorescence. The antimycobacterial properties of the SDN formulations and aqueous prepa- rations of RIF and INH (solubilised per product instruc- tions) were assessed using the previously described assay (Donnellan et al. 2015). Viable Map K10/GFP (2 × 10 6 cfu/mL) was exposed to SDNs and aqueous drugs ranging in concentrations (0.001875 – 1.33 μ g/mL) for 7 days. Following exposure to the SDNs the growth of Map K10/GFP was inhibited in a dose-dependent and time-dependent manner, but differing in ef ﬁ cacy between SDN types. The growth rates of Map K10/GFP were expressed as the change in ﬂ uorescence per day ( β ) (Donnellan et al. 2015) and plotted against drug concentration using the data modelling software
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The bactericidal/permeability-increasing protein (BPI) with bactericidal and endotoxin-neutralizing activity is of considerable interest in clinical applications. However, the crucial residues responsible for the bactericidal activity of BPI remain elusive. In previous study, we identified the mutation of mBPI5 associated with the male infertility of mice. Here, the effects of Asp190Ala mutation on the antibacterial activity of mBPI5 have been determined. Substitution of Asp190 by alanine caused significant improvement in cytotoxic effect toward both E.coli J5 and P.aeruginosa. Liposome co-sedimentation assay showed that the ratio of Asp190Ala mutant binding to lipids increased by 8 folds. These results were well consistent with known fact that antibacterial activity of BPI is attributed to its high affinity for lipid moiety of lipopolysaccharides (LPS). The constructed structure of mBPI5 revealed that Asp190 was located close to 6 positively charged residues on the surface of N-terminal domain. When replacing Asp190 with alanine, salt linkages with Arg188 were broken, making the side chain of Arg188 be free to move and form tighter contacts with negatively charged LPS. These findings suggest that residue 190 combined with surrounding positively charged residues largely contribute to bactericidal and endotoxin-neutralizing activities of mBPI5.
Previous studies identified several factors that can affect anti- FHbp bactericidal activity, even when there is a match between the vaccine FHbp subfamily and the subfamily of the strain. The most important factors are the extent of amino acid identity between the strain FHbp variant and vaccine antigen (16, 22, 29) and the level of strain FHbp expression (5, 7, 30, 31). Additionally, the ability of meningococci to bind human FH using alternative li- gands, such as NspA (32, 33) or PorB (34, 35), can increase resis- tance to anti-FHbp bactericidal activity (34) (by FH downregula- tion of complement activation). It is noteworthy that the more susceptible isolates from the university B outbreak expressed FHbp ID 1, which is an exact match to FHbp in the MenB-4C vaccine, whereas the less susceptible isolates from university A expressed FHbp ID 276, with 96% amino acid identity to ID 1. In immunized mice, even this small difference in amino acid sequence can have a large effect on anti-FHbp bactericidal ac- tivity, depending on the locations of the amino acid residues (29). Further, while the isolates from both outbreaks were high expressers of FHbp, the university B isolates had greater sur- face-accessible FHbp detected by flow cytometry than the iso- lates from university A. Thus, the greater anti-FHbp bacteri- cidal titers against the university B isolates likely resulted from greater expression of an FHbp that exactly matched the variant FIG 4 Depletion of serum anti-FHbp antibodies. A post-dose 2 immunization serum pool from five rhesus macaques vaccinated with MenB-4C, and a post-dose 3 immunization serum from an immunized human were depleted of anti-FHbp antibodies by incubation with FHbp coupled with Sepharose (see Materials and Methods). The untreated sera, the FHbp-depleted sera, and the mock-adsorbed sera were tested by ELISA for IgG antibodies to FHbp, NadA, NHba, and OMV. The FHbp depletion removed ⬎ 99% of the anti-FHbp antibodies but had no significant effect on the serum antibody titers to NadA, NHba, or OMV.
Furthermore, a product’s overall formulation and active ingredients play a role in bactericidal efficacy. Previous work by our group demonstrated that a sodium hypochlorite-based disinfectant product was significantly more effective against multiple MRSA strains than a quaternary ammonium compounds (quat)- based prod- uct . Other published studies have also shown that disinfectants with differing active ingredients have differ- ent bactericidal efficacies against the same microorgan- ism [6, 7, 10, 11]. Thus, understanding factors that can reduce bactericidal efficacy are important to help under- stand how to optimize the performance of a disinfectant. Ready-to-use (RTU) disinfectants in the form of pre-wetted towelettes are increasingly popular among healthcare facilities. A 2014 study determined that the use of RTU disinfectant towelette products led to a fas- ter disinfection process, higher compliance with disinfec- tion standards, and overall cost savings as compared to traditional disinfection methods . The CDC specific- ally recommends using an Environmental Protection Agency (EPA)-registered disinfectant product for envir- onmental cleaning in healthcare facilities . The current EPA methodology used to register a disinfectant towelette product is the qualitative AOAC Germicidal Spray Products as Disinfectants Test modified for towel- ettes . This protocol only requires testing of small carriers (25 mm × 75 mm glass slides) as opposed to lar- ger surfaces areas that are more representative of actual product usage. Currently, the EPA does not require dis- infectant manufacturers to include a recommended maximum surface area per towelette on their product labels. Thus, there are a number of important applica- tion considerations that are not informed by the current EPA wipe testing method.
the silk is consumed for the treatment of urinary troubles and gallstones. 3-5 The ash of the cob is used for the treatment of cough 4 as well as inflammatory diseases and depression. The husks are used in the treatment of pains and arthritis. 6 Warm tea of the husks is used for the treatment of malaria and diabetes in Ibibio traditional medicine. Analgesic, anti-inflammatory, and antioxidant activities have been reported on the husk extract. 6,7 Arabinoxylan, which has immunological effects, has been isolated from the husk extract, 8 while eight phenolic compounds (gallic acid, protocatechuic acid, chlorogenic acid, cafeic acid, femlic acid,
Shojaei Moghadam et al. investigated the anti-staphylococcal potency of 8 native medicinal plants of Iran. The tested bacterial strains were clinical isolates with resistance to methicillin and cefixime. As a result, the extracts of Peganum harmala, Quercus brantii, Oliveria decumbens and Ziziphus spina-Christ among the studied plants had high inhibitory effect against MRSA and their effects were related to their concentrations. Quercus brantii that is a native plant in Iran was the most potent plant for inhibition of S. aureus. So, it can be suggested that these plants can be considered for further studies and finding the active constituents of these plants. 1
In another study on bactericidal properties of Lignans in sesame seeds on three bacterial species, the obtained results showed complete inhibition of the growth of B. cereus when facing the Sesamol in concentration of 2 mg/ml. 30 A study on synergism of sesame oil and canola oil showed that the mixture of these two oils is more antioxidant than each oil individually. In the current study, the mixture of the oils not only were not more antibacterial than each oil but also it had less antibacterial effect than olive oil. 21
In a study that started evaluating the antibacterial activity of Coriander on P.aeruginosa with micro plate method, indicated MIC and MBC of aqueous extract of coriander plant on this bacteria 50, 100 mg/ml and ethanolical extract 25, and 50 mg/ml, respectively. By comparing these results with results of the present study, it can be found out that olive oil in comparison with alcoholic and aqueous extracts of coriander has more growth inhibition but this oil has less bactericidal effect than ethanolic extract, although sesame oil and the synergism of sesame oil and olive oil have less antibacterial effect than these two extracts. 27
For this reason, we decided to study on the effects of anti-bacterial features of plant Callistemon viminalis on the common standard number of bacteria in the urinary tract infection. Then, we investigated the combined effects of methanol extract of Callistemon viminalis plant with two antibiotics, vancomycin and ciprofloxacin, to show this extract has a strengthening or an inhibitory effect on the function of the antibiotics. At last, the results of the study show this product is effective in combination with antibiotics and leads to treatment of urinary tract infections.
sample populations were 1.8 · 10 5 and 1.88 · 10 5 CFU/plate, respectively). The authors showed that S. aureus has a higher sensitivity to ozone at the initial stage of treatment (first ∼20 s); however, the paper does not discuss any specific processes and mechanisms which are responsible for this difference in ozone sensitivity. It was also found that ozone inactivation efficiencies for treatment times above ∼60 s are very similar for these two microorganisms, and on this basis, the authors concluded that the ozone resistance mechanisms are not species dependent. The authors measured only O 3 concentration in their tests; however, as discussed earlier, the corona discharges in air generate other toxic (reactive oxygen and nitrogen) species which can also produce a noticeable bactericidal effect , . The results of  are in good agreement with that of this paper in which a higher sensitivity of S. aureus to indirect corona treatment has been observed. Potentially, this higher sensitivity of the Gram-positive S. aureus to plasma treatment as compared with the Gram-negative E. coli can be explained by the secondary outer cell membrane of Gram-negative bacteria which provides an elevated level of protection against external stresses. Similar effect has been observed in  in which these two species of microorganism were subjected to the action of the ionization products generated by a candle’s flame.
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In this work, we investigate the antibacterial potential of the synthetic bSi surface, together with its related dragonﬂy Diplacodes bipunctata wing surface, and compare the antibacter- ial behaviour to that previously obtained for cicada wing surfaces. The physicochemical properties of bSi and native wing surfaces are chemically and structurally characterized prior to assessing their antibacterial activity against three different bacterial strains with a variety of cell wall structures. The surfaces of bSi and dragonﬂy are highly bactericidal against all tested Gram-negative and Gram-positive bacteria, and endospores, and both surfaces exhibit estimated average killing rates of up to B450,000 cells min 1 cm 2 . This represents the ﬁrst reported physical bactericidal activity of bSi or indeed for any hydrophilic surface.