Fluorescent Peptide-Containing Naphthalimide-Conjugated Boronic Acid-Based Nanoassembly for Rapid Mitochondrial Targeting and Antibacterial Activity.

In 2019, minimum inhibitory concentration (MIC) breakpoints of ciprofloxacin and levofloxacin for Enterobacterales were lowered. This study sought to determine whether there is a correlation between MIC and outcomes in those receiving fluoroquinolones (FQs) for urinary tract infections (UTIs) caused by Enterobacterales pathogens. This was a retrospective study of adult patients treated with ciprofloxacin or levofloxacin for a UTI caused by an Enterobacterales pathogen. Patients were placed into low MIC (ciprofloxacin: ≤ 0.25mcg/mL; levofloxacin ≤ 0.5mcg/mL), intermediate MIC (ciprofloxacin: 0.5-2 mcg/mL; levofloxacin: 1-4 mcg/mL), or high MIC groups (ciprofloxacin: > 2 mcg/mL; levofloxacin: > 4 mcg/mL). The primary outcome was UTI recurrence, defined as hospital admission, emergency department or clinic visit due to UTI, or antibiotic prescription within 28days of FQ initiation. A total of 1022 patients were included: 887, 75, and 60 with a low, intermediate, and high MIC, respectively. UTI recurrence within 28days occurred most frequently in the high MIC group (20.5% vs. 25.3% vs. 60%; P < 0.01). Risk factors for UTI recurrence identified by multivariable analysis were those with a high MIC (high vs. low MIC: OR 5.20, 95% CI 2.99-9.05, P < 0.01; high vs. intermediate MIC: OR 4.72, 95%CI 2.22-10.03, P < 0.01), a complicated UTI (OR 1.85, 95% CI 1.35-2.54; P < 0.01), a history of recurrent UTIs (OR 1.84, 95% CI 1.29-2.62; P < 0.01), or a respiratory disorder (OR 1.58, 95% CI 1.04-2.42; P = 0.03). This study supports separate, less stringent FQ MIC breakpoint interpretive criteria for UTIs caused by Enterobacterales pathogens.

BackgroundThe Clinical and Laboratory Standards Institute reduced the levofloxacin minimum inhibitory concentration (MIC) breakpoint from ≤2 to ≤0.5 mg/L for Enterobacteriaceae in 2019 guidelines. The reduction is based on Monte Carlo simulations for a levofloxacin dose of 750 mg daily. The aim of this study was to determine whether there was a difference in clinical outcomes in the treatment of Enterobacteriaceae bacteremia with levofloxacin step-down therapy retrospectively comparing patients with isolates with low levofloxacin MICs (≤0.5 mg/L) to high MICs (1–2 mg/L).MethodsThis retrospective, two-center cohort study included patients ≥18 years of age with a monomicrobial Enterobacteriaceae bacteremia with a levofloxacin MIC ≤2 mg/L from March 2017 through December 2018. Patients had to have received treatment with ≥3 days of levofloxacin step-down therapy, initial intravenous therapy with an agent active against the isolated organism, and total duration not exceeding 16 days from first negative blood culture. A subset of patients whose isolates had low levofloxacin MICs were randomly selected for comparison to all patients with high levofloxacin MICs in a 3:1 ratio. The primary outcome was a composite endpoint of recurrence and mortality within 30 days of completion of the antibiotic course. Secondary outcomes included post-culture length of stay (LOS) and 30-day readmission rate.ResultsThirty-three patients with high MIC and 99 with low MIC were included. Urinary source was predominant and occurred in 44% of patients, and Escherichia coli was the infecting organism in 48%. Over 80% of patients experienced source resolution or control. The composite endpoint occurred in 8.1% of the low MIC group and 9.1% of the high MIC group (P = 0.856). Median LOS was 4.9 days (IQR 3.7–8.0) in the low MIC group and 4.3 days (IQR 3.2–6.8) in the high MIC group (P = 0.384), and readmission rate was 17.2% in the low MIC group and 15.2% in the high MIC group (P = 0.787).ConclusionThere was no between-group difference in the primary outcome of recurrence and mortality, with a low overall event rate and short LOS post-culture. These results suggest that levofloxacin effectiveness may be sustained in patients with MICs of 1 or 2 despite levofloxacin not meeting susceptibility criteria by new definitions.DisclosuresAll authors: No reported disclosures.

High vancomycin minimum inhibitory concentration and clinical outcomes in adults with methicillin-resistant Staphylococcus aureus infections: a meta-analysis

Strong expression of neuron restrictive silencer factor (NRSF) has been observed in many aggressive types of cancer cells and mature neurons. However, the function of the neuron restrictive silencer element (NRSE)/NRSF system in KB human oral cancer cells is unknown. Findings from previous studies in our lab have demonstrated the importance of NRSF as a factor in regulationof cell proliferation of KB human oral cancer cells. Treatment of KB cells with NRSF siRNA resulted in signifi cant inhibitionof cell growth through repression of NRSF expression. In this study, in order to understand the NRSE/NRSF regulatory network in KB cells, we performed microarray analysis in KB cells treated with NRSF specifi c targeted siRNA. The expression profi les of several genes were further validated in KB cells treated with NRSF siRNA. Results of microarray analysis showed upregulation of 117 genes and down-regulation of 215 genes in KB cells treated with NRSF siRNA. Most of the up-regulated genes were involved in signal transduction, cell communication, cell cycle, and apoptosis;down-regulated genes were involved in RNA processing, neurogenesis, transcription factor activity, and synaptogenesis. NRSF is known as a transcriptional repressor for silencingof neuronal genes; however, according to our data, treatment of KB cells with NRSF siRNAresulted in down-regulation of more than 200 genes. As a result, genes identifi ed in this screen represent a novel control pathway via NRSF expression in KB oral cancer cells. Further investigation will be needed in order to defi ne the mechanism of gene regulation by expression of NRSF in KB human oral cancer cells.

To determine the antibacterial and cytotoxic activities of aqueous and ethanolic extracts of northwestern Argentinian plants used in folk medicine. To compare the mentioned activities with those of five commercial antibiotics. To identify the compounds responsible for the antibacterial activity. Plant extracts were prepared according to traditional uses in northwestern Argentina. Antibacterial activity was assayed by agar dilution in Petri dishes and broth dilution in 96-well plates. Lethal dose 50 (LD(50)) was determined by the Artemia salina assay. Phytochemical analysis was performed by sample adsorption on silica gel, thin-layer chromatography (TLC), bioautography and UV-visible spectra. The results showed that Tripodanthus acutifolius aqueous extracts have lower minimal inhibitory concentrations (MIC) (502 and 506 microg of extracted material (EM) per ml for infusion and decoction, respectively) than cefotaxim MIC (640 microg ml(-1)) against Acinetobacterfreundii (303). These data were lower than their LD(50). Tripodanthus acutifolius tincture showed lower MIC (110 microg of EM per ml) and minimal bactericidal concentration (MBC) (220 microg of EM per ml) than cefotaxim (MIC and MBC of 320 microg ml(-1)) for Pseudomonasaeruginosa. This extract also showed a MIC/MBC of 110/220 microg of EM per ml, lower than oxacillin (MIC/MBC of 160/220 microg ml(-1)) for Staphylococcus aureus (ATCC 25923). The cytotoxicity of all extracts were compared with that of commercial antibiotics. Rutin (3,3',4',5,7-pentahydroxyflavone 3-beta-rhamnosilglucoside), iso-quercitrin (3,3',4',5,7-pentahydroxyflavone 3-beta-glucoside) and a terpene would be partially responsible for the antibacterial activity of T. acutifolius infusion. Tripodanthus acutifolius extracts had the ability to inhibit bacterial growth. The antibacterial activity differs with the applied extractive method, and it could be partially attributed to glycoflavonoids. This paper contributes to the knowledge of antibacterial capacity of plants from northwestern Argentina. These antibacterial activities support further studies to discover new chemical structures that can contribute to alleviate or cure some illnesses.

Chemical composition of Mentha pulegium and Rosmarinus officinalis essential oils and their antileishmanial, antibacterial and antioxidant activities

The systematic application of spices as natural food preservatives could be the key to withstanding different food-borne diseases and the frequent use of antibiotics could be reduced thereby. Eight indigenous spices were tested against six food-borne pathogens. The spice extracts were prepared by drying, grinding, and soaking into 95% ethanol and the antibacterial activity was evaluated by the well-diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by the broth dilution method. The feasibility of spices as natural meat preservatives was then assessed through the application. The ethanol extracts of the spices potentially inhibited the test organisms. Maximum activity (zone of inhibition- ZOI) was recorded for garlic (17.83±2.48 mm) followed by black pepper (17±8.9 mm), black cumin (15.83±10.87 mm), and ginger (15.16±7.68 mm). For pathogens, the most susceptible was B. cereus (19.57±8.05 mm) followed by Acinetobacter sp. (18.14±1.34 mm), E. coli (16.28±1.88 mm), S. aureus (14.28±9.91 mm), V. cholerae (10.85±7.94 mm) and Salmonella enterica ser. Typhi (6.85±8.55 mm). Garlic exhibited the most effective and consistent inhibitory activity whereas black cumin exhibited the highest activity against B. cereus (34 mm). These results were highly comparable to the commercial antibiotics, e.g. Meropenem (28 mm). Against the Salmonella spp., ginger, cumin, and garlic demonstrated moderate inhibition (16 mm) whereas complete resistance was observed against other spices. The lowest MIC and MBC were recorded for black cumin against B. cereus (32 mg/ml and 64 mg/ml, respectively). But garlic was found to be the best candidate due to its lowest mean MIC (85.33±33 mg/ml), and MBC (170.66±66 mg/ml). Black cumin, garlic, and black pepper were efficient in reducing the total viable count of meat at 72 hours and hence could be developed as natural food preservatives. Stamford Journal of Microbiology, Vol.12 (1) 2022: 31-36

Oral squamous cell carcinoma (OSCC) is an aggressive epithelial malignancy with limited therapeutic options and high recurrence rates. C-Phycocyanin, a phycobiliprotein derived from Spirulina platensis, exhibits promising anticancer properties by modulating various molecular pathways. This study aimed to investigate the cytotoxic and pro-apoptotic effects of C-Phycocyanin on human oral cancer cells (KB) and compare its safety profile on normal endothelial cells (HUVECs). Cell viability was assessed using the MTT assay in both KB and HUVEC cell lines following treatment with different concentrations of C-Phycocyanin. Apoptotic features were evaluated by DAPI nuclear staining and quantified using Annexin V/PI-based flow cytometry. The expression of apoptosis-related genes (P53, Bax, Bcl-2) and signaling molecules involved in the Akt/PTEN and MAPK (ERK2) pathways was analyzed by semi-quantitative RT-PCR. C-Phycocyanin significantly inhibited the viability of KB cells in a dose-dependent manner while exerting minimal cytotoxic effects on HUVEC cells. DAPI staining revealed nuclear fragmentation and chromatin condensation in KB cells. Flow cytometry confirmed apoptosis induction. RT-PCR analysis showed upregulation of P53 and Bax and downregulation of Bcl-2, suggesting activation of the intrinsic apoptotic pathway. In addition, C-Phycocyanin inhibited Akt and upregulated PTEN and MAPK (ERK2) pathway components. C-Phycocyanin effectively induces apoptosis in oral cancer cells by modulating key molecular pathways, with minimal toxicity on normal cells. These results support its potential as a natural and selective therapeutic agent for OSCC, meriting further in vivo validation.

ObjectiveThe use of the vancomycin minimum inhibitory concentration (MIC) as a prognostic predictor in patients with methicillin-susceptible Staphylococcus aureus (MSSA) has been debated in the last decade. We performed a...

Activity of telithromycin against 26 quinolone-resistant pneumococci with known quinolone-resistance mechanisms

Oral squamous cell carcinoma (OSCC), a global threatening disease, is reported mostly in the middle and elderly male population. Even though the exact cause of OSCC was not known, consumption of tobacco in any form has been reported in most of OSCC patients. OSCC is a massive invasive type of cancer which easily spreads to the distant organs. Hence treating it at appropriate time is necessary and the rate of OSCC incidence is also constantly increasing. At present, chemoradiation is the only therapy prescribed for OSCC patients which renders various side effects. Hence, the treatment with lesser side effect was of current research interest. Doxazosin (α1 adrenorecptor antagonist) had been proven to render anticancer effect in prostate, renal, hepatic, and ovarian cancers but its role in oral cancer cells was not been elucidated. Therefore, we have assessed the anticancer effect of doxazosin on oral squamous cancer cells via through the induction of apoptosis, and antioxidant property. The cytoprotective effect of doxazosin on normal Vero cells and anticancer effect on oral cancer KB cells were analyzed with MTT assay. Doxazosin antioxidant activity were analyzed by their reactivity with free radicals and metal ions by the method of FRAP, DPPH, chemilumiscence, and ORAC assay. The antioxidant levels were also assessed by TBARS, SOD, and glutathione levels, and later on apoptosis staining techniques like DCFH-DA, Rhodamine 123, and AO/EtBr stain were conducted. Apoptosis was confirmed by estimating the levels of apoptotic proteins in doxazosin-treated KB human oral cancer cells by ELISA method. The results from our study show that doxazosin is a potent antioxidant and it significantly induces apoptosis in human oral cancer by altering various cellular molecules at downstream signaling which has been depict in the results. Our study proves doxazosin as a potent anticancer drug which may be used in the treatment of oral carcinoma, if it is subjected to further research using human clinical trials.

Chimonanthus salicifolius S. Y. Hu. (FCS) possess many biological activities, but the antibacterial activity and underlying mechanisms of flavonoids from Chimonanthus salicifolius S. Y. Hu. (FCS) is still unknown. Maximum diameter of inhibition zone (DIZ), maximum diameter of inhibition zone (DIZ), the lowest minimum inhibition concentration (MIC), and the lowest minimum bactericide concentration (MBC) were used to detect the antibacterial activity. Meanwhile, related enzyme activities, the transcriptome analysis and quantitative RT-PCR were used to investigate the antibacterial activity mechanisms. The results showed that FCS (with a purity of 84.2 ± 2.0%) has potential effects on tested strains with the maximum diameter of inhibition zone (DIZ) was 15.93 ± 2.63 mm, the lowest minimum inhibition concentration (MIC) was 1.56 mg/ml and the lowest minimum bactericide concentration (MBC) was 6.25 mg/ml. In addition, the bacterial growth curve test, release of extracellular alkaline phosphatase (AKP), loss of intracellular components, DNA damage and transmission electron microscope (TEM) suggested that FCS could destroy the cell wall and membrane, cause the loss of intracellular substance, cause DNA damage and even lead to cell death. Moreover, the antibacterial mechanism of FCS against Staphylococcus aureus (S. aureus, Gram-positive bacteria) was further confirmed by the transcriptome analysis and quantitative RT-PCR at the molecular level for the first time. A total of 671 differentially expressed genes (DEGs) were identified after treated with FCS (1/2 MIC), with 338 and 333 genes showing up-regulation and down-regulation, respectively. The highlighted changes were those related to the biosynthesis of bacteria wall and membrane, DNA replication and repair, and energy metabolism. Overall, our research provides theoretical guidance for the application of FCS, which is expected to be potentially used as a natural antimicrobial agent in food safety.

A propensity score-matched analysis of the impact of minimum inhibitory concentration on mortality in patients with Pseudomonas aeruginosa bacteremia treated with cefepime or ceftazidime

Background: Meropenem is a broad-spectrum carbapenem widely used in the treatment of critically ill patients. A generic meropenem product has recently become available in South Africa and we aimed to compare the generic product with the innovator product using established in vitro microbiological testing methods. Method: Comparative minimum inhibitory concentrations (MICs) were determined for 115 clinically relevant isolates using the broth microdilution reference method. Comparative analysis of MIC was done using categorical and essential agreement. A subset of isolates was evaluated using minimum bactericidal concentration (MBC) testing. Results: The overall essential agreement exceeded the international standard of > 90%. A single major error and six minor errors were detected in 230 comparative MICs. For the 55 Enterobacteriaceae isolates tested, the MIC 50 and MIC 90 were 0.03 µg/ml and 0.06 µg/ml respectively, with no difference between extended–spectrum s-lactamase producers (ESBL) and non-ESBL isolates. Bactericidal activity was demonstrated for both generic and innovator products in all isolates tested. For eight of the 11 isolates, the MBC was only twice the MIC. Conclusion: Reference method MIC and MBC testing of a large sample of clinically relevant microorganisms against meropenem has demonstrated comparable in vitro activity between the innovator and generic products. Low MICs and bactericidal activity at concentrations close to the MIC indicate that meropenem remains a useful agent in the treatment of infections caused by ESBLproducing Enterobacteriaceae.

Endophytes associated with medicinal plants are a potential source of valuable natural products. This study aimed to evaluate the antibacterial and antibiofilm activities of endophytic bacteria from Archidendron pauciflorum against multidrug-resistant (MDR) strains. A total of 24 endophytic bacteria were isolated from the leaf, root, and stem of A. pauciflorum. Seven isolates showed antibacterial activity with different spectra against four MDR strains. Extracts derived from four selected isolates (1mg/mL) also displayed antibacterial activity. Among four selected isolates, DJ4 and DJ9 isolates exhibited the strongest antibacterial activity against P. aeruginosa strain M18, as indicated by the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) (DJ4 and DJ9 MIC: 7.81µg/mL; DJ4 and DJ9 MBC: 31.25µg/mL). 2 × MIC of DJ4 and DJ9 extracts was found to be the most effective concentration to inhibit more than 52% of biofilm formation and eradicate more than 42% of established biofilm against all MDR strains. 16S rRNA-based identification revealed four selected isolates belong to the genus Bacillus. DJ9 isolate possessed nonribosomal peptide synthetase (NRPS) gene, and DJ4 isolate possessed NRPS and polyketide synthase type I (PKS I) gene. Both these genes are commonly responsible for secondary metabolites synthesis. Several antimicrobial compounds, including 1,4-dihydroxy-2-methyl-anthraquinone and paenilamicin A1, were detected in the bacterial extracts. This study highlights endophytic bacteria isolated from A. pauciflorum provide a great source of novel antibacterial compounds.