Concentrations Of Minocycline Research Articles

Antibiotic Combination to Effectively Postpone or Inhibit the In Vitro Induction and Selection of Levofloxacin-Resistant Mutants in Elizabethkingia anophelis.

Fluoroquinolones are potentially active against Elizabethkingia anophelis. Rapidly increased minimum inhibitory concentrations (MICs) and emerging point mutations in the quinolone resistance-determining regions (QRDRs) following exposure to fluoroquinolones have been reported in E. anophelis. We aimed to investigate point mutations in QRDRs through exposure to levofloxacin (1 × MIC) combinations with different concentrations (0.5× and 1 × MIC) of minocycline, rifampin, cefoperazone/sulbactam, or sulfamethoxazole/trimethoprim in comparison with exposure to levofloxacin alone. Of the four E. anophelis isolates that were clinically collected, lower MICs of levofloxacin were disclosed in cycle 2 and 3 of induction and selection in all levofloxacin combination groups other than levofloxacin alone (all p = 0.04). Overall, no mutations were discovered in parC and parE throughout the multicycles inducted by levofloxacin and all its combinations. Regarding the vastly increased MICs, the second point mutations in gyrA and/or gyrB in one isolate (strain no. 1) occurred in cycle 2 following exposure to levofloxacin plus 0.5 × MIC minocycline, but they were delayed appearing in cycle 5 following exposure to levofloxacin plus 1 × MIC minocycline. Similarly, the second point mutation in gyrA and/or gyrB occurred in another isolate (strain no. 3) in cycle 4 following exposure to levofloxacin plus 0.5 × MIC sulfamethoxazole/trimethoprim, but no mutation following exposure to levofloxacin plus 1 × MIC sulfamethoxazole/trimethoprim was disclosed. In conclusion, the rapid selection of E. anophelis mutants with high MICs after levofloxacin exposure could be effectively delayed or postponed by antimicrobial combination with other in vitro active antibiotics.

Minocycline relieves neuropathic pain in rats with spinal cord injury via activation of autophagy and suppression of PI3K/Akt/mTOR pathway

ObjectiveIn this study, we studied whether minocycline hydrochloride improved neuropathic pain induced by spinal cord injury (SCI) in rats through PI3K/Akt pathway. MethodsThe SCI was induced by compressed at level of T9-T11 of spinal cord in Sprague Dawley male rats. Animals were given different concentrations of minocycline (3 mg/kg, 30 mg/kg, 90 mg/kg) at the first and 24 h after SCI, then subsequently every 7, 12, 16, 20, 25 days via peroral route. The locomotor function was assessed by Basso Mouse Scale (BMS). The changes of spinal cord tissues were observed by HE. The inflammatory cytokines in spinal cord, IL-6, IL-1β and TNF-α, were measured by ELISA. The LC3B levels of spinal cord were observed by immunofluorescence. The autophagy related proteins and PI3K/AKT pathway related proteins were analysed by Western blot. Furthermore, the PI3K/AKT pathway inhibitor LY294002, and activator IGF-1 were used to confirm the mechanism of minocycline. ResultsContrasted to sham group, the inflammatory response in spinal cord was enhanced after SCI. Compared with the SCI rats, minocycline treatment significantly improved the locomotor activity, pathological injury of spinal cord, suppressed the levels of inflammatory factors. In addition, minocycline treatment upregulated autophagy response in damaged spinal cord through increasing LC3B, Beclin-1 and decreasing P62. The results of mechanism study showed that minocycline treatment clearly suppressed phosphorylation of PI3K, Akt and mTOR proteins expression. ConclusionMinocycline could improve neuropathic pain induced by SCI through activating autophagy and inhibiting PI3K/AKT/mTOR pathway.

High fluorescent nitrogen − doped carbon dots derived from Sanghuangporus lonicericola for detecting tetracyclines in aquaculture water and rat serum samples

Tetracyclines (TCs) are a kind of broad − spectrum and effective antibiotics that have been widely used in veterinary and human medicine, which may pose serious risk to human health if they are accumulated in human body. The fluorescence method using nanomaterials as probes has been gradually used for the detection of TCs because of its simple operation, high sensitivity and recognition ability. Herein, a novel nitrogen doped carbon dots (N − CDs) derived from Sanghuangporus lonicericola was synthesized by hydrothermal method. The N − CDs exhibited bright blue fluorescence, high quantum yield (QY) of 60.99 %, and excellent photostability, which was employed as a fluorescent probe for selective detection of TCs, including oxytetracycline (OXY), doxycycline (DOX), tetracycline (TCY) and minocycline (MNO). The fluorescence intensity of the N − CDs decreased linearly with the increasing concentration of OXY, DOX, TCY and MNO, and their concentrations were in the range of 0.6 – 73.3 μM, 0 – 95.2 μM, 6.5 – 72.3 μM and 10 – 52.6 μM, respectively. As for practical application, the as − prepared N − CDs could not only be effectively applied for determination of TCs in aquaculture water and rat serum samples with low relative standard deviation (RSD) and good recoveries, but also track the concentration change of TCs in rats blood model over time. Towards the fluorescence detection mechanism, the results of UV–vis absorption spectra and fluorescence lifetimes proved that the fluorescent quenching of N − CDs occurred from internal filtration effect (IFE) in the presence of TCs. This work provides guidance for the development of new TCs sensors based on fluorescent nanomaterials, and has a good application prospect in the quality control of agriculture, food and pharmaceutical production processes.

A Case of Mycobacteriosis in Cultured Japanese Seabass (Lateolabrax japonicus) in Southern China

Japanese seabass (Lateolabrax japonicus) is an important species of cultured marine fish with high economic value in China. Nevertheless, from May to November 2019, mass mortality among cultured Japanese seabass occurred in Zhuhai City, Guangdong Province of China. Approximately 0.2–0.5% mortality was recorded daily, and the cumulative mortality was up to 30% during this disease outbreak. In this study, the clinical signs and pathological characteristics of diseased fish were investigated. Furthermore, the pathogenicity and antibiotic sensitivity of identified pathogenic bacteria from diseased fish were analyzed. The infected fish showed clinical signs of uncoordinated swimming; anorexia; pigment changes; and a number of 1–5 mm grayish-white nodules in the liver, spleen, and kidney tissues was also found. A bacterial strain, which was designated as ZHLJ2019, was isolated from the diseased fish. To ensure that ZHLJ2019 isolate was the causative agent, a Koch postulate trial was performed. Healthy Japanese seabass were infected by the intraperitoneal injection of 5 × 104, 5 × 105 and 5 × 106 CFU/fish, and cumulative mortalities within 42 days were 75%, 90%, and 100%, respectively. The bacteria colony had traditional morphological and biochemical characteristics similar to that of Mycobacterium marinum. Phylogenetic molecular analyses of 16S rRNA, rpoB, hsp65, erp, and ITS genes confirmed that the isolated strain ZHLJ2019 was M. marinum. The granulomatous inflammation in internal organs of Japanese seabass naturally and experimentally infected with ZHLJ2019 isolate was consistent with the classic pathological features of mycobacteriosis. Drug susceptibility of ZHLJ2019 isolate to 11 antibiotics was determined by broth dilution method in vitro. The minimum inhibitory concentrations (MICs) of minocycline, rifampicin, ethambutol, isoniazid, streptomycin, doxycycline hydrochloride, kanamycin sulfate, levofloxacin, roxithromycin, and prothionamide against the strain ZHLJ2019 were 4, 2, 8, 4, 16, 8, 8, 8, 4, and 8 μg/mL, respectively. The results of this study suggest that M. marinum is the causal agent responsible for the morbidity and mortality of Japanese seabass cultured in intensive brackish water dirt ponds in southern China.

Antidepressant-Like Effects of Edaravone and Minocycline: Investigation of Oxidative Stress, Neuroinflammation, Neurotrophic, and Apoptotic Pathways.

Depression is a very common mental disorder and mechanism that is associated with mitochondrial dysfunction. In the present study, we examined the mechanisms of action of isolated brain mitochondria in rats with depression for the first time. This will help identify the mitochondrial protective pathways of the two drugs and shed light on new therapeutic goals for developing antidepressants. Forced swimming, tail suspension, and sucrose preference tests were used to assess depressive-like behaviors and the oxidative stress factors of brain tissue, and measure the gene expression of apoptotic and anti-apoptotic, neuroplasticity, and neuroinflammatory factors by RT-PCR and acetylcholinesterase (AChE) activity in brain tissue (hippocampus and prefrontal) and the serum levels of corticosterone and fasting blood sugar. The results showed that the separation of neonatal rats from their mothers induced depressive-like behaviors, weight loss, mitochondrial dysfunction, increased expression of genes involved in neuroinflammation, apoptosis, genes involved in the depressive process, and decreased expression of genes involved in mood in both the hippocampus and prefrontal cortex. Maternal separation increased serum corticosterone levels, caused dysfunction of the cholinergic system, and also increased AChE activity. Treatment with different concentrations of minocycline and edaravone (1, 20, and 50mg/kg), 5MTHF, and citalopram for 14days showed that these drugs improved depression-like behaviors and mitochondrial function. It also reduced the expression of genes involved in neuroinflammation, apoptosis, and depression and increased the expression of genes involved in mood. In conclusion, minocycline and edaravone have neuroprotective, mitochondrial protective, antioxidant, anti-inflammatory, and anti-apoptotic effects against depressive-like behaviors caused by chronic stress.

Effect of regulating macrophage polarization phenotype on intervertebral disc degeneration.

BackgroundMacrophages are the only inflammatory cells that can penetrate the closed nucleus pulposus and their polarization plays an important role in intervertebral disc degeneration (IVDD). This paper attempted to investigate the pathogenesis of IVDD by altering the polarization state of macrophages.MethodsMacrophage RAW264.7 cells were induced by interferonγ (IFN‐γ) and lipopolysaccharide (LPS). The polarization of RAW264.7 cells was estimated by western blot and immunofluorescence. The expressions of inflammatory factors were detected by ELISA. Subsequently, RAW264.7 cells were treated with different concentrations of minocycline (Mino) and sinomenine (Sino), followed by the assessment of cell viability with cell counting kit‐8 kit. Then, RAW264.7 cell culture medium was collected for the culture of human nucleus pulposus cells (NPCs). Toluidine blue staining and type II collagen staining were applied to assay the level of type II collagen. The cell apoptosis, oxidative stress, and nitric oxide (NO) level were appraised by TUNEL, oxidative stress kits and NO kit, respectively. Western blot was employed to test the levels of apoptosis‐ and oxidative stress‐related proteins.ResultsIFN‐γ and LPS could induce M1 polarization of RAW264.7 cells. Mino and Sino could reduce the polarization of RAW264.7 cells toward M1. M1‐polarized medium inhibited LPS‐induced activity, inflammation, and damage of NPCs, which were enhanced by Mino and Sino in medium.ConclusionM1 polarization of macrophages promoted LPS‐induced inflammation and damage of NPCs.

Investigating the immunomodulatory activities of omadacycline.

Apart from their antimicrobial activities, some antibiotics have immunomodulatory effects on host cells, particularly monocytes. Because hyperactivation of the pro-inflammatory cytokine response contributes to acute lung injury in patients with bacterial pneumonia and other lung diseases, antimicrobial agents with immunomodulatory activity can reduce cytokine-mediated tissue injury and improve outcomes. Omadacycline has been recently FDA-approved for community-acquired bacterial pneumonia and acute bacterial skin and skin-structure infections. The present study investigated omadacycline's ability to modulate LPS-induced production of pro-inflammatory cytokines (TNF-α, IL-1β), acute-phase reactants (IL-6) and anti-inflammatory cytokines (IL-4, IL-10) by human monocytes in vitro. Isolated human monocytes from healthy consenting adults were cultured in RPMI with 1% pooled human serum. Cells were pre-exposed to omadacycline (0.5-64 μg/mL), minocycline (25, 50 or 25 μg/mL) or azithromycin (20, 40 or 80 μg/mL) for 2 h, followed by stimulation with Escherichia coli LPS for 24 h. Cytokines elaborated in the culture supernatant were quantitated by multiplex immunoassay. Omadacycline dose-dependently suppressed LPS-induced production of all cytokines tested. Only high-dose minocycline (100 μg/mL) modestly suppressed TNF-α whereas minocycline significantly increased LPS-induced IL-1β production. Lower concentrations of minocycline were also stimulatory for IFN-γ, IL-6 and IL-4. Except for suppression of IL-6, azithromycin was largely without effect. Omadacycline has unique and broad immunomodulatory properties. Such activity supports its use in settings where hyperactivation of the immune response contributes to tissue injury and poor outcomes, especially at sites where pro-inflammatory M-type 1 macrophages dominate the cellular immune response.

In vitro and in vivo efficacy of minocycline-based therapy for Elizabethkingia anophelis and the impact of reduced minocycline susceptibility

ObjectivesElizabethkingia anophelis is inherently resistant to multiple antibiotics, except minocycline. This study aimed to determine the in vitro and in vivo efficacy of minocycline monotherapy and combination therapy against susceptible strains and the impact of reduced minocycline susceptibility. MethodsThree clinical isolates and one laboratory-induced mutant with reduced minocycline susceptibility were included. Time-kill and checkerboard assays were used to assess in vitro efficacy and synergy, respectively. Galleria mellonella infection and mouse pneumonia models were used to assess in vivo efficacy, and a mouse thigh infection model was used to determine the bacterial load. ResultsMinocycline monotherapy exerted a modest inhibitory effect on three clinical minocycline-susceptible E. anophelis isolates in vitro, but delayed G. mellonella death and improved infected mouse survival; it also significantly reduced the in vivo bacterial load. Minocycline had decreased efficacy on G. mellonella and mice infected by the mutant with reduced minocycline susceptibility. Genome comparison revealed several spontaneous mutations associated with reduced minocycline susceptibility. Among eight antibiotics tested in combination with minocycline, rifampin consistently showed in vitro synergy. The addition of rifampin (1 mg/L) reduced the mutant prevention concentration of minocycline from 2–4 mg/L to < 0.5 mg/L. However, compared with monotherapy, the combination of rifampin and minocycline did not further reduce the bacterial load or improve the survival of G. mellonella or mice. ConclusionMinocycline monotherapy was in vivo effective against susceptible E. anophelis. Reduced minocycline susceptibility due to spontaneous mutation decreased its therapeutic efficacy. In combination with rifampin, it prevented the in vitro emergence of reduced susceptibility but did not provide additional in vivo survival benefit.

Efficacy of Ciprofloxacin, Metronidazole and Minocycline in Ordered Mesoporous Silica against Enterococcus faecalis for Dental Pulp Revascularization: An In-Vitro Study.

Pulp revascularization of teeth with necrotic pulp has become an alternative treatment in cases with immature apex. Microbial control is essential to achieve a successful outcome and continued root development. Enterococcus faecalis (E. faecalis) is the most frequently isolated bacterial species in root canals of endodontically failed teeth. Our main goal was to compare the in-vitro antimicrobial efficacy of different antibiotic formulations delivered by ordered mesoporous silica (OMS) against E. faecalis. To determine antibiotic susceptibility, we tested OMS and triple antibiotic paste (TAP; ciprofloxacin:metronidazole:minocycline) with different reagents in different concentrations, using the Kirby–Bauer disk diffusion method. OMS and metronidazole showed no antibacterial activity against E. faecalis. Mixtures of OMS and antibiotics in proportions of 2:2:14 and 4:1:7 (mg/L of ciprofloxacin:metronidazole:minocycline, respectively) showed the lowest antibacterial activity. The antibacterial activity of the combined solutions of ciprofloxacin and metronidazole was significantly higher (p < 0.005). Combinations in different concentrations of minocycline, ciprofloxacin, and metronidazole in OMS have shown activity against E. faecalis, although the combined use of ciprofloxacin and metronidazole has shown the most effective results. This study demonstrates the efficacy of intracanal antibiotic combination paste activity against E. faecalis, avoiding the use of minocycline, whose undesirable effect of teeth staining is a common problem for patients and professionals in dental clinic.

The Eagle effect in the Wolbachia-worm symbiosis

BackgroundOnchocerciasis (river blindness) and lymphatic filariasis (elephantiasis) are two human neglected tropical diseases that cause major disabilities. Mass administration of drugs targeting the microfilarial stage has reduced transmission and eliminated these diseases in several countries but a macrofilaricidal drug that kills or sterilizes the adult worms is critically needed to eradicate the diseases. The causative agents of onchocerciasis and lymphatic filariasis are filarial worms that harbor the endosymbiotic bacterium Wolbachia. Because filarial worms depend on Wolbachia for reproduction and survival, drugs targeting Wolbachia hold great promise as a means to eliminate these diseases.MethodsTo better understand the relationship between Wolbachia and its worm host, adult Brugia pahangi were exposed to varying concentrations of doxycycline, minocycline, tetracycline and rifampicin in vitro and assessed for Wolbachia numbers and worm motility. Worm motility was monitored using the Worminator system, and Wolbachia titers were assessed by qPCR of the single copy gene wsp from Wolbachia and gst from Brugia to calculate IC50s and in time course experiments. Confocal microscopy was also used to quantify Wolbachia located at the distal tip region of worm ovaries to assess the effects of antibiotic treatment in this region of the worm where Wolbachia are transmitted vertically to the microfilarial stage.ResultsWorms treated with higher concentrations of antibiotics had higher Wolbachia titers, i.e. as antibiotic concentrations increased there was a corresponding increase in Wolbachia titers. As the concentration of antibiotic increased, worms stopped moving and never recovered despite maintaining Wolbachia titers comparable to controls. Thus, worms were rendered moribund by the higher concentrations of antibiotics but Wolbachia persisted suggesting that these antibiotics may act directly on the worms at high concentration. Surprisingly, in contrast to these results, antibiotics given at low concentrations reduced Wolbachia titers.ConclusionWolbachia in B. pahangi display a counterintuitive dose response known as the “Eagle effect.” This effect in Wolbachia suggests a common underlying mechanism that allows diverse bacterial and fungal species to persist despite exposure to high concentrations of antimicrobial compounds. To our knowledge this is the first report of this phenomenon occurring in an intracellular endosymbiont, Wolbachia, in its filarial host.Graphical

Synthesis of novel Ag@ZIF-67 rhombic dodecahedron for enhanced adsorptive removal of antibiotic and organic dye

Ag@ZIF-67 was successfully prepared by using a facile and fast method at room temperature and characterized by a variety of techniques. Results indicate that prepared Ag@ZIF-67 contains a very beautiful morphology with a great active specific surface area than solo ZIF-67. The prepared Ag@ZIF-67 contains a greater pore size, which is 1.564 nm with increased functional sites. The adsorption performance of Ag@ZIF-67 was further studied with the removal of Minocycline (MC) and methyl orange (MO) from polluted water. Various adsorption parameters, such as contact time, adsorbent dosage, pH, and initial concentrations of MC and MO, were optimized. The kinetics parameters of the adsorption process were determined by applying the pseudo first-order kinetic model (PFO) and pseudo second-order (PSO) kinetic model. In the case of MC, adsorption isotherm data matched well with Freundlich as compared to Langmuir and Temkin model. While in the case of MO, adsorption isotherm data followed the Langmuir model as compared to the Freundlich and Temkin model. Ag@ZIF-67 was found to be an efficient adsorbent for the adsorption of MC and MO, having 938.4 mg/g and 994.6 mg/g adsorption capacity, which is higher than reported adsorbents.

Cigarette smoke extract induces the Pseudomonas aeruginosa nfxC drug-resistant phenotype

BackgroundThere is clinical and epidemiological evidence indicating that cigarette smoke exposure can significantly increase the usage of antibiotics by smokers to treat pulmonary infections, suggesting an increased risk of bacterial drug resistance. Pseudomonas aeruginosa is commonly found in infectious diseases closely related to cigarette smoke exposure and frequently acquires drug resistance. Recently, a study has demonstrated that cigarette smoke extract may induce Pseudomonas aeruginosa antibiotic resistance but the mechanism remain unknown. ObjectivesTo explore the effect of cigarette smoke exposure on drug resistance in P. aeruginosa and the underlying mechanism using an in vitro model of cigarette smoke extract (CSE) exposure. MethodsP. aeruginosa strains PAO1, PA103 and ATCC27853 were used in this study. Changes in drug resistance in P. aeruginosa after CSE exposure were evaluated by antimicrobial susceptibility tests. Additionally, differentially expressed genes related to drug resistance were detected by transcriptome sequencing and qRT-PCR. ResultsCSE increased both the MIC and MBC of levofloxacin and imipenem (MIC was not changed in ATCC 27853) against P. aeruginosa. However, CSE could only increase the minimum inhibitory concentration of tigecycline and minocycline against P. aeruginosa. Transcriptome sequencing and qRT-PCR indicated that MvaT and OprD levels decreased and MexEF-OprN levels increased. ConclusionsOverall, our results showed that CSE may induce antibiotic resistance in P. aeruginosa. The results of antimicrobial susceptibility tests, transcriptome sequencing and qRT-PCR showed that CSE induced P. aeruginosa to the nfxC drug-resistant phenotype.

Genotoxic effect of non-lethal concentrations of minocycline in human glial cell culture

Minocycline has been proposed as a neuroprotective agent with pleiotropic effects on several experimental models of neurodegenerative diseases, including microglial inhibition. However, although most studies have focused on the central actions of minocycline in affecting microglial functions, other central nervous system (CNS) cell types may also be affected by this drug toxicity. Hence, considering that glial cells play a pivotal role on CNS physiology and are the main responsible for neuronal integrity, a comprehensive investigation on the effects of minocycline treatment on human glial cells is mandatory before translational studies to afford neuroprotection in humans. Therefore, we explored the cytotoxic and genotoxic effects of minocycline at different concentrations in glial cells using an in vitro model. To achieve this, U87 glial cell were exposed to 10–50 μg/mL for 24 h. After exposure, cell viability, general metabolic status and genotoxic assays were performed. No changes were observed in cell viability, however, the general metabolic status decreased over 20 μg/mL. In addition, although no chromossome aberrations were observed, evidences of genotoxicity, such as increase on micronucleus, buds and bridges, were observed from 10 μg/mL. These results suggest that minocycline may induce genotoxic effects even at concentrations considered previously safe and should be used with caution in translational studies.

Taurolidine Acts on Bacterial Virulence Factors and Does Not Induce Resistance in Periodontitis-Associated Bacteria-An In-Vitro Study.

The aims of the present study were: (a) to determine the mechanism of action of taurolidine against bacterial species associated with periodontal disease, and (b) to evaluate the potential development of resistance against taurolidine as compared with minocycline. After visualizing the mode of action of taurolidine by transmission electron micrographs, the interaction with most important virulence factors (lipopolysaccharide (LPS), Porphyromonas gingivalis gingipains, Aggregatibacter actinomycetemcomitans leukotoxin), was analyzed. Then, 14 clinical isolates from subgingival biofilm samples were transferred on agar plates containing subinhibitory concentrations of taurolidine or minocycline up to 50 passages. Before and after each 10 passages, minimal inhibitory concentrations (MICs) were determined. Increasing MICs were screened for efflux mechanism. Taurolidine inhibited in a concentration-dependent manner the activities of LPS and of the arginine-specific gingipains; however, an effect on A. actinomycetemcomitans leukotoxin was not detected. One P. gingivalis strain developed a resistance against taurolidine, which was probably linked with efflux mechanisms. An increase of MIC values of minocycline occurred in five of the 14 included strains after exposure to subinhibitory concentrations of the antibiotic. The present results indicate that: (a) taurolidine interacts with LPS and gingipains, and (b) development of resistance seems to be a rare event when using taurolidine.

ClpP participates in stress tolerance, biofilm formation, antimicrobial tolerance, and virulence of Enterococcus faecalis

BackgroundClpP is important for bacterial growth and plays an indispensable role in cellular protein quality control systems by refolding or degrading damaged proteins, but the physiological significance of ClpP in Enterococcus faecalis remains obscure. A clpP deletion mutant (△clpP) was constructed using the E. faecalis OG1RF strain to clarify the effect of ClpP on E. faecalis. The global abundance of proteins was determined by a mass spectrometer with tandem mass tag labeling.ResultsThe ΔclpP mutant strain showed impaired growth at 20 °C or 45 °C at 5% NaCl or 2 mM H2O2. The number of surviving ΔclpP mutants decreased after exposure to the high concentration (50× minimal inhibitory concentration) of linezolid or minocycline for 96 h. The ΔclpP mutant strain also demonstrated decreased biofilm formation but increased virulence in a Galleria mellonella model. The mass spectrometry proteomics data indicated that the abundances of 135 proteins changed (111 increased, 24 decreased) in the ΔclpP mutant strain. Among those, the abundances of stress response or virulence relating proteins: FsrA response regulator, gelatinase GelE, regulatory protein Spx (spxA), heat-inducible transcription repressor HrcA, transcriptional regulator CtsR, ATPase/chaperone ClpC, acetyl esterase/lipase, and chaperonin GroEL increased in the ΔclpP mutant strain; however, the abundances of ribosomal protein L4/L1 family protein (rplD), ribosomal protein L7/L12 (rplL2), 50S ribosomal protein L13 (rplM), L18 (rplR), L20 (rplT), 30S ribosomal protein S14 (rpsN2) and S18 (rpsR) all decreased. The abundances of biofilm formation-related adapter protein MecA increased, while the abundances of dihydroorotase (pyrC), orotate phosphoribosyltransferase (pyrE), and orotidine-5′-phosphate decarboxylase (pyrF) all decreased in the ΔclpP mutant strain.ConclusionThe present study demonstrates that ClpP participates in stress tolerance, biofilm formation, antimicrobial tolerance, and virulence of E. faecalis.

Immediate Treatment of Burn Wounds with High Concentrations of Topical Antibiotics in an Alginate Hydrogel Using a Platform Wound Device.

Objective: There is an unmet need to improve immediate burn care, particularly when definitive treatment is delayed. Therefore, the purpose of this project was to formulate a hydrogel that contains very high concentrations of antibiotics and validate its use together with a platform wound device (PWD) for the immediate care of burns. Approach: The hydrogel properties were optimized by using a rheometer, differential scanning calorimetry, and liquid chromatography-mass spectrometry and were tested in an infected porcine burn model. Immediately, after burn creation, the burns were infected with different bacteria. Subsequently, the burns infected with Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii were covered with the PWD and treated with a single dose of hydrogel containing 1000 × minimum inhibitory concentration of vancomycin, gentamicin, and minocycline, respectively. On day 7 or 45, the animals were euthanized, and the burns were harvested for histology and quantitative bacteriology. Results: 0.625% was the best alginate concentration for the hydrogel in terms of viscosity, stability, and drug release. The porcine studies demonstrated that vancomycin-, gentamicin-, and minocycline-treated tissues contained significantly less bacteria and reduced depth of tissue necrosis in comparison to controls. Innovation: The PWD represents a platform technology that begins at the point of the first treatment by protecting the wound and allowing administration of topical therapeutics. The device can be adapted to enclose any size burn over any contour of the body. Conclusion: Antibiotics can be delivered safely in very high concentrations in a hydrogel using the PWD, and burn infections can be treated successfully with this method.

Antibiotic-Containing Agarose Hydrogel for Wound and Burn Care.

Wound infections cause inflammation, tissue damage, and delayed healing that can lead to invasive infection and even death. The efficacy of systemic antibiotics is limited due to poor tissue penetration that is especially a problem in burn and blast wounds where the microcirculation is disrupted. Topical administration of antimicrobials is an attractive approach because it prevents infection and avoids systemic toxicity, while hydrogels are an appealing vehicle for topical drug delivery. They are easy to apply to the wound site by being injectable, the drug release properties can be controlled, and their many characteristics, such as biodegradation, mechanical strength, and chemical and biological response to stimuli can be tailored. Hydrogels also create a moist wound environment that is beneficial for healing. The purpose of this study was to formulate an agarose hydrogel that contains high concentrations of minocycline or gentamicin and study its characteristics. Subsequently, the minocycline agarose hydrogel was tested in a porcine burn model and its effect as a prophylactic treatment was studied. The results demonstrated that 0.5% agarose in water was the optimal concentration in terms of viscosity and pH. Bench testing at room temperature demonstrated that both antibiotics remained stable in the hydrogel for at least 7 days and both antibiotics demonstrated sustained release over the time of the experiment. The porcine burn experiment showed that prophylactic treatment with the agarose minocycline hydrogel decreased the burn depth and reduced the number of bacteria as efficiently as the commonly used silver sulfadiazine cream.

Synergistic effects of LFchimera and antibiotic against planktonic and biofilm form of Aggregatibacter actinomycetemcomitans.

Adjunctive use of antibiotics in periodontal treatment have limitations and disadvantages including bacterial resistance. Antimicrobial peptides (AMPs) are potential new agents that can combat bacterial infection. In this study, antimicrobial activity of different concentrations of conventional antibiotics minocycline (MH), doxycycline (DOX), and antimicrobial peptides LL-37, LL-31, Lactoferrin chimera (LFchimera) and Innate Defense Regulator Peptide 1018 (IDR-1018) against Aggregatibacter actinomycetemcomitans ATCC 43718 were determined using colony culturing assay. Subsequently, in vitro activity of the most effective drug and peptide combination was evaluated by checkerboard technique. Impact of the drug and peptide co-administration on biofilm at different stages, i.e., during adhesion and 1-day old biofilm was compared to each of the agents used alone. Results revealed that the killing effects of all AMPs range from 13–100%. In contrast, MH and DOX at 1 and 5 μM showed no killing activity and instead stimulated growth of bacteria. DOX has better killing activity than MH. LFchimera displayed the strongest killing amongst the peptides. Checkerboard technique revealed that combining DOX and LFchimera yielded synergism. Confocal laser scanning microscopy further showed that the combination of DOX and LFchimera caused significant reduction of bacterial adhesion and reduction of biomass, average biofilm thickness and substratum biofilm coverage of 1-day old biofilm compared to DOX and LFchimera alone. In conclusion, LFchimera alone and in combination with DOX exhibited strong antibacterial and anti-biofilm property against A. actinomycetemcomitans. The findings suggest that LFchimera should be considered for development as a new potential therapeutic agent that may be used as an adjunctive treatment for periodontitis.

Biofilm prevention concentrations (BPC) of minocycline compared to polymyxin B, meropenem, and amikacin against Acinetobacter baumannii

Infections caused by Acinetobacter baumannii are difficult to treat as they are often multidrug resistant (MDR) and frequently form biofilms. We investigated the activities of minocycline, polymyxin B, meropenem, and amikacin against diverse Acinetobacter baumannii strains with biofilm formation classified as weak versus moderate/strong. At clinically achievable concentrations, minocycline prevented biofilm formation for 96% of isolates versus 54% for polymyxin B, 29% for meropenem and 29% for amikacin. Minocycline and polymyxin B demonstrated highest in vitro activity against A. baumannii and prevented biofilm formation for a majority of isolates.

Molecular epidemiology & therapeutic options of carbapenem-resistant Gram-negative bacteria.

Background & objectives:The growing incidence and the wide diversity of carbapenemase-producing bacterial strains is a major concern as only a few antimicrobial agents are active on carbapenem-resistant bacteria. This study was designed to study molecular epidemiology of carbapenem-resistant Gram-negative bacterial (GNB) isolates from the community and hospital settings.Methods:In this study, non-duplicate GNB were isolated from clinical specimens, and phenotypic test such as modified Hodge test, metallo β-lactamase E-strip test, etc. were performed on carbapenem-resistant bacteria. Multiplex PCR was performed to identify the presence of blaIMP, blaVIM, blaKPC, blaOXA48, blaOXA23, blaSPM, blaGIM, blaSIM and blaNDM. Minimum inhibitory concentration (MIC) of colistin, fosfomycin, minocycline, chloramphenicol and tigecycline was also determined.Results:Of the 3414 GNB studied, carbapenem resistance was 9.20 per cent and maximum resistance (11.2%) was present at tertiary care centre, followed by secondary care (4%) and primary centre (2.1%). Among the carbapenem-resistant bacteria, overall, the most common isolate was Pseudomonas aeruginosa (24%). On multiplex PCR 90.3 per cent carbapenem-resistant isolates were positive for carbapenemase gene. The blaNDM (63%) was the most prevalent gene followed by blaVIM (18.4%). MIC results showed that 88 per cent carbapenem-resistant Enterobacteriaceae were sensitive to fosfomycin, whereas 78 per cent of P. aeruginosa and 85 per cent Acinetobacter spp. were sensitive to colistin.Interpretation & conclusions:Carbapenem resistance in GNB isolates from the community and hospital settings was found to be on the rise and should be closely monitored. In the absence of new antibiotics in pipeline and limited therapeutic options, prudent use of antibiotics and strict infection control practices should be followed in hospital to limit the emergence and spread of multidrug-resistant bacteria.