Lowest Minimum Inhibitory Concentration Value Research Articles

Influence of Ag, Au and Pd noble metals doping on structural, optical and antimicrobial properties of zinc oxide and titanium dioxide nanomaterials

Oxide materials (ZnO, TiO2) doped with noble metals were synthesized using the combustion technique. The results of the addition of Ag, Au, and Pd up to a concentration of 2 mol% on the structural, optical, morphological and antimicrobial properties was considered. X-ray diffraction experiments revealed that the crystal structure of the host materials remained unaltered despite doping with noble metals. From the scanning electron microscopy results, it was evident that the doped nanoparticles aggregated in clusters of different sizes in the host matrix. The plasmonic effect was also observed in the absorbance spectra of the different doped materials. The obtained materials have shown promising antimicrobial features. All ZnO materials exhibited a high antimicrobial activity, with very low minimum inhibitory concentration values, against the planktonic growth of all tested Gram-positive and Gram-negative bacterial strains. All doped materials exhibited very good anti-biofilm activity, the lowest minimal biofilm eradication concentration values being registered for ZnO doped with Au and Pd toward Escherichia coli and for ZnO doped with Ag against Candida albicans. These results indicate the potential that these materials have for antimicrobial applications in the fields of biomedicine and environmental protection.

Microbial Biosynthesis of Antibacterial Chrysoeriol in Recombinant Escherichia coli and Bioactivity Assessment

Various flavonoid derivatives including methoxylated flavones display remarkable biological activities. Chrysoeriol is a methoxylated flavone of great scientific interest because of its promising anti-microbial activities against various Gram-negative and Gram-positive bacteria. Sustainable production of such compounds is therefore of pronounced interest to biotechnologists in the pharmaceutical and nutraceutical industries. Here, we used a sugar O-methyltransferase enzyme from a spinosyn biosynthesis gene cluster of Saccharopolyspora spinosa to regioselectively produce chrysoeriol (15% conversion of luteolin; 30 µM) in a microbial host. The biosynthesized chrysoeriol was structurally characterized using high-resolution mass spectrometry and various nuclear magnetic resonance analyses. Moreover, the molecule was investigated against 17 superbugs, including thirteen Gram-positive and four Gram-negative pathogens, for anti-microbial effects. Chrysoeriol exhibited antimicrobial activity against nine pathogens in a disc diffusion assay at the concentration of 40 µg per disc. It has minimum inhibitory concentration (MIC) values of 1.25 µg/mL against a methicillin-resistant Staphylococcus aureus 3640 (MRSA) for which the parent luteolin has an MIC value of sixteen-fold higher concentration (i.e., 20 µg/mL). Similarly, chrysoeriol showed better anti-microbial activity (~1.7-fold lower MIC value) than luteolin against Proteus hauseri, a Gram-negative pathogen. In contrast, a luteolin 4′-O-methylated derivative, diosmetin, did not exhibit any anti-microbial activities against any tested pathogen.

Antimicrobial Activity of Different Antimicrobial Peptides (AMPs) Against Clinical Methicillin-resistant Staphylococcus aureus (MRSA).

Antimicrobial research is being focused to look for more effective therapeutics against antibiotic-resistant infections caused by methicillin-resistant Staphylococcus aureus (MRSA). In this direction, antimicrobial peptides (AMP) appear as promising tool. This study evaluated the antimicrobial activity of different AMPs (Citropin 1.1, Temporin A, Pexiganan, CA(1-7)M(2-9)NH2, Pal-KGK-NH2, Pal-KKKK-NH2, LL-37) against human MRSA clinical isolates. The Minimum Inhibitory Concentration (MIC) was assessed for each AMP; then, the most active ones (Citropin 1.1, Temporin A, CA(1-7)M(2-9)NH2 and Pal-KGK-NH2) were tested against selected MRSA strains by time-kill studies. The lowest MIC value was observed for Pal-KGK-NH2 (1 µg/ml), followed by Temporin A (4- 16 µg/ml), CA(1-7)M(2-9)NH2 (8-16 µg/ml) and Citropin 1.1 (16-64 µg/ml), while higher MICs were evidenced for LL-37, Pexiganan and Pal-KKKK-NH2 (> 128 µg/ml). In time-kill experiments, Citropin 1.1 and CA(1-7)M(2-9)NH2 showed a relatively high percentage of growth inhibition (>30 %) for all the tested MRSA clinical isolates, with a dose-dependent activity resulting in the highest percentage of bacterial growth inhibition (89.39%) at 2MIC concentration. Overall, our data demonstrated the potential of some AMPs against MRSA isolates, such as Citropin 1.1 and CA(1-7)M(2-9)NH2, that represents a promising area of development for different clinical applications.

Sulfonamide-Derived Four-Component Molecular Hybrids as Novel DNA-Targeting Membrane Active Potentiators against Clinical Escherichia coli.

Novel sulfonamide-based four-component molecular hybrids as potential DNA-targeting antimicrobial agents were developed from marketed acetanilide through convenient procedures. Biological assays indicated that a few of the target compounds showed significant inhibitory efficiencies toward the tested bacteria and fungi. Noticeably, metronidazole hybrid 6a exhibited a lower minimum inhibitory concentration (MIC) value of 0.019 mM against clinical drug-resistant Escherichia coli ( E. coli), which showed to be 84-fold more active than clinical norfloxacin and had no obvious toxicity toward human breast cancer MCF-7 cells. Synergistic combinations of compound 6a with clinical antibacterial or antifungal drugs could improve the antimicrobial efficiency. Further molecular modeling indicated that the active molecule 6a could bind with THR-199, HIS-64, and GLN-92 residues of human carbonic anhydrase isozyme II through hydrogen bonds and was also able to insert into base-pairs of the DNA hexamer duplex by forming hydrogen bonds. The preliminary exploration of the antibacterial mechanism suggested that compound 6a was capable of disturbing the E. coli membrane effectively and intercalating into clinical resistant E. coli bacterial DNA through noncovalent bonds to form a supramolecular complex, thus exerting its powerful antimicrobial activity. This might suggest a great possibility for hybrid 6a to be a DNA-targeting membrane active potentiator against clinical drug-resistant E. coli.

Antibacterial activity of Alstonia angustifolia leaf extract against Staphyloccoccal and Bacilli

Alstonia angustifolia were applied in traditional medicine to cure malaria disease and remittent fever. The aim of this study is to evaluate the potential antibacterial properties of A. angustifolia leaf extract under in vitro condition. The leaf extract was tested on various Gram-positive and Gram-negative bacteria to evaluate the inhibition pattern using disc diffusion assay, minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) technique. Disk diffusion assay showed that S. aureus, S. epidermidis, S. saprophyticus, B. cereus and B. subtilis were susceptible to the extract while K. pneumonia, P. aeruginosa, S. typhi, A. baumannii and E. coli were resistant. The lowest MIC values were 6.25 mg/ml, 12.5 mg/ml for S. aureus and B. subtilis respectively, at 24 h and 48 h of incubation period. The MBC value for S. aureus, B. subtilis and B. cereus showed no different, within 24 h and 48 h, however the other values had raised. The plant has potential to be commercialized in pharmaceutical and other industries.

Comparison of Minimum Inhibitory Concentration (MIC) value of statin drugs: A Systematic Review

Background: Microbial infection and its resistance to clinically approved drugs create a huge threat to human health. Emerging reports have indicated the potential of statin drugs in the treatment of various types of microbial infections. However, it is still unclear, how much concentration of statin is effective against microbial infections. In literature, Minimum Inhibitory Concentration (MIC) values of statin drugs vary according to strain, species, and the type of statins. Thus, the main aim of the current study is to compare the MIC values of various types of statins against various types of micro-organisms. The data related to statin and microbial infection has been extracted from Pub Med (from September 1 Methodology: 987 to October 2017). A total of 662 studies have been published from 1987 -2017 regarding statin and microbial infections. After inclusion and exclusion criteria, finally, 28 studies have been selected for comparative analysis of MIC values. Results: All the statin drugs have shown a significant effect on various types of microbial infections. Among all the tested statin drugs, Simvastatin has lower MIC value in almost all types of microorganisms as compared to other statin drugs. However, on S. pneumoniae and aspergillus, Fluvastatin has the lowest MIC values as compared to Simvastatin. Atorvastatin was found to be the most potent against almost all strains of gram-negative bacteria. However, Rosuvastatin and Pravastatin have high MIC value against all types of microorganisms. Further, FICI value indicated the synergetic effect of Simvastatin with Amphotericin B, Itraconazole, and Fluconazole against various strains of Cryptococcus. Conclusion: In conclusion, Simvastatin, Atorvastatin, and Fluvastatin could be developed as potential antimicrobial agents. However, further studies are required to understand its complete safety and efficacy profile..

Antibiotic susceptibility profiles of Mycoplasma hyorhinis strains isolated from swine in Hungary

Mycoplasma hyorhinis is a common pathogen of swine causing mainly polyserositis and arthritis, but it has also been implicated as a cause of pneumonia. The economic losses due to M. hyorhinis infection could be reduced by antibiotic treatment. The aim of this study was to determine minimal inhibitory concentrations (MIC) of antibiotics potentially used to combat M. hyorhinis in swine production.Thirty-eight Hungarian M. hyorhinis strains isolated between 2014 and 2017 were examined by microbroth dilution tests for fifteen antimicrobial agents. Low MIC values of tetracyclines (MIC50 0.078 μg/ml for doxycycline, ≤0.25 μg/ml for oxytetracycline) and pleuromutilins (MIC50 0.156 μg/ml for tiamulin, ≤0.039 μg/ml for valnemulin) were detected against all strains. Fluoroquinolones (MIC50 0.625 μg/ml), gentamicin (MIC50 1 μg/ml) and florfenicol (MIC50 2 μg/ml) inhibited the growth of Hungarian isolates at moderate MIC values. Most of the strains were inhibited by spectinomycin with low or moderate MIC values (MIC50 4 μg/ml) except one strain (>64 μg/ml). Numerous isolates showed decreased susceptibility to macrolides and lincomycin (MIC90 >64 for tylosin, tilmicosin, tulathromycin, gamithromycin, lincomycin, 8 μg/ml for tylvalosin).This study serves as evidence for the increasing resistance to macrolides and lincomycin in mycoplasmas, and also reports the occurrence of strains with extremely high MIC values to spectinomycin thus emphasizes the importance of the prudent use of antibiotics. Based on our results, tetracyclines and pleuromutilins are the most active compounds in vitro against the Hungarian M. hyorhinis strains.

2433. Evaluation of Meropenem (MEM) in Combination With Colistin (COL) Against Colistin-Resistant Extensively Drug-Resistant (XRD) Gram-Negative Bacteria

BackgroundThe treatment of XDR Gram-negative bacilli poses a significant clinical challenge with limited treatment options. Colistin-resistant XRD Gram-negative bacteria are becoming more commonplace in the clinical setting. Combination therapy is resorted to for treatment of such strains. The objective of this in-vitro study was to evaluate the synergistic effect of the combination with COL and MEM against Colistin-resistant XDR Gram-negative bacilli.MethodsIn this study, a total of 30 Colistin-resistant XDR Gram-negative clinical isolates were evaluated, including five isolates of Pseudomonas aeruginosa, twenty-four isolates of Acinetobacter baumannii and one isolate of Klebsiella pneumonia. Minimum inhibitory concentrations (MICs) were determined with COL and MEM for each strain by broth microdilution. COL and MEM MICs were measured in the presence of 0.25- to 0.5- × the MIC of the other antibiotic to determine the ability to lower MIC values. Time-kill assays were performed with each agent alone and in combination to evaluate the potential for synergistic interactions. Additive and synergistic effects were defined as 1- to 2-log10 and ≥ 2-log10 reductions in CFU/mL from the most active single agent at 24 hours, respectively.ResultsAll isolates were resistant to COL (MIC90 32 mg/L), whereas all bacteria with except one A. baumannii, were resistant to MEM (MIC90 >64 mg/L). Zero- to greater than nine-fold decrease in MEM MICs were observed in combination with COL at 0.25- to 0.5 × MIC. COL MICs decreased by 0 to >8-fold when combined with MEM. MEM plus COL demonstrated synergistic activity against 70% strains tested and additive in 3% of the tested strains at 24 h in time-kill. The combination was indifferent in 26% of the tested strains.ConclusionThese data indicate that the addition of MEM to COL therapy in colistin resistant XDR Gram-negative bacteria demonstrate synergistic or additive effects against a majority of XDR Gram-negative bacteria. The combination might be a promising therapeutic option for treatment of these problem pathogens.Disclosures M. J. Rybak, Allergan: Consultant, Grant Investigator and Speaker’s Bureau, Research grant and Research support. Achaogen: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Bayer: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Melinta: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Merck: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Theravance: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Sunovian: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. Zavante: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support. NIAID: Consultant, Grant Investigator and Speaker’s Bureau, Consulting fee, Research grant and Research support.

Biogenic Synthesis and Characterization of Silver Nanoparticles Using Some Medical Plants and Evaluation of Their Antibacterial and Toxicity Potential.

Background: Silver nanoparticles (AgNPs) are employed in various applications in the areas of catalysis, optoelectronics, detection and diagnostics, antimicrobials, and therapeutics. Objective: The aim of this work was to study the antimicrobial activity of aqueous and methanolic leaf extracts of Thymus vulgaris and Urtica dioica and biologically prepared silver nanoparticles, as single or in combination treatments, against Escherichia coli and methicillin-resistant Staphylococcus aureus isolates. Methods: The minimum inhibitory concentration (MIC) was quantified by using a microdilution method in sterile 96-well microtiter plates. The assessment of the toxicity of AgNP solutions was evaluated on human blood lymphocyte cells. Results: The results of this study revealed that all AgNP solutions have the lowest MIC values against the bacterial isolates in relation with the methanolic and aqueous extract solutions. However, the results showed that the increasing AgNP concentration was a critical factor influencing the interaction between AgNPs and the human lymphocytes. Conclusions: The cytotoxicity of nanoparticles increased significantly (P < 0.05) at high concentrations. In addition, the biosynthesized AgNPs have an increased antimicrobial activity against all tested bacterial isolates. Highlights: AgNPs have been recognized as an effective antimicrobial agent that exhibits low toxicity in humans and has diverse in vitro and in vivo applications.

Design of Antibacterial Agents: Alkyl Dihydroxybenzoates against Xanthomonas citri subsp. citri.

Xanthomonas citri subsp. citri (Xcc) causes citrus canker, affecting sweet orange-producing areas around the world. The current chemical treatment available for this disease is based on cupric compounds. For this reason, the objective of this study was to design antibacterial agents. In order to do this, we analyzed the anti-Xcc activity of 36 alkyl dihydroxybenzoates and we found 14 active compounds. Among them, three esters with the lowest minimum inhibitory concentration values were selected; compounds 4 (52 μM), 16 (80 μM) and 28 (88 μM). Our study demonstrated that alkyl dihydroxybenzoates cause a delay in the exponential phase. The permeability capacity of alkyl dihydroxybenzoates in a quarter of MIC was compared to nisin (positive control). Compound 28 was the most effective (93.8), compared to compound 16 (41.3) and compound 4 (13.9) by percentage values. Finally, all three compounds showed inhibition of FtsZ GTPase activity, and promoted changes in protofilaments, leading to depolymerization, which prevents bacterial cell division. In conclusion, heptyl dihydroxybenzoates (compounds 4, 16 and 28) are promising anti-Xcc agents which may serve as an alternative for the control of citrus canker.

Antibacterial and Antioxidant Activities of Ocimum basilicum L. Against Mastitis Pathogens

The most common bacterial agents cause inflammation in the mammary gland (mastitis), which disease cause to less yields in cows. These bacteria are Staphylococcus aureus and Coagulase-negative Staphylococci (CNS). Therefore, these bacteria were selected in this study. The purpose of this study is to research the antibacterial and antioxidant potential of the various extracts of Ocimum basilicum L. The mastitis agents used in the study are 7 bacteria in total; 2 of them are Staphylococcus aureus and the other 5 bacteria are CNS. The antibacterial activities studies were carried out using Kirby-Bauer disc diffusion technique. The other antibacterial activity test performed within the scope of this study was minimum inhibitory concentration (MIC) test. Antioxidant activities were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method. This study showed that the largest inhibition zone was obtained from the methanol extract of O. basilicum. Result of this study is 9 mm. The lowest MIC value was recorded as 3250 μg/mL. It was found that O. basilicum used in the study had antibacterial activity against mastitis pathogens, and high antioxidant activity could be obtained from the water extracts (72%). Consequently, O. basilicum is a good candidate in developing new antibacterial and antioxidant agents.

Lipase production from Cryptococcus albidus D24 using disposed automotive oil

Both valinomycin and cereulide are cyclic depsipeptides and are known K+ ion-selective ionophores. Valinomycin and cereulide feature low minimum inhibitory concentration (MIC) values against Candida albicans and Cryptococcus albidus. This study aims at investigating the mode of action and verifying the efficacy of valinomycin or cereulide alone and in combination with amphotericin B (AmB) in vitro against both microorganisms. Based on the results from membrane permeability and fluidity assays for detection of plasma membrane permeabilization and membrane dynamics, the present study demonstrated that valinomycin and cereulide exhibit antifungal activity against C. albicans and C. albidus by interrupting membrane-associated function. The mode of action of both valinomycin and cereulide are similar with that of AmB. Time-kill kinetics assay showed that valinomycin and cereulide exhibit fungistatic activity, whereas AmB features fungicidal activity. Additionally, the combination of compounds between each cyclic peptide and AmB reached maximal fungicidal activity more rapidly than AmB alone. This result corresponded with findings of scanning electron microscopy, fractional inhibitory concentration index and minimum fungicidal concentration (MFC)/MIC ratio, indicating that combinations of the drugs show synergistic effects for inhibiting the growth of these fungal strains. Sorbitol and ergosterol assays showed that both cyclic peptides affected cell wall and membrane components due to increases in MIC value, as observed in medium with sorbitol and ergosterol. Valinomycin and cereulide may promote permeability of fungal cell wall and cell membrane when used in combination with AmB.

Chemical composition and antibacterial activity of Origanum ramonense essential oil on the β-lactamase and extended- spectrum β-lactamase urinary tract isolates

&lt;p class="Abstract"&gt;The aim of this study was to evaluate the antibacterial activity of &lt;em&gt;Origanum ramonense&lt;/em&gt; essential oil extracted from the air-dried leaves against β-lactamase and extended-spectrum β-lactamase obtained from the patients with urinary tract infection. The essential oil was extracted by hydrodistillation and analyzed by GC–MS. In vitro antibacterial activity was studied using disc diffusion and microdilution methods. Twenty compounds were identified representing 97.8% of the total oil. The major components were carvacrol (84.6%), p-cymene (4.3%) and γ-terpinene (3.3%). The oil showed a broad spectrum of antibacterial activity against all tested isolates. &lt;em&gt;Staphylococcus aureus, S. epidermidis, Klebsiella pneumoniae&lt;/em&gt; and &lt;em&gt;Enterobacter aerogenes&lt;/em&gt; had the lowest minimum inhibitory concentration values (0.015 µg/mL) followed by &lt;em&gt;Escherichia coli&lt;/em&gt; (0.14 µg/mL). The lowest susceptible strains to oil were &lt;em&gt;Pseudomonas aeruginosa, Proteus mirabilis, E. coli&lt;/em&gt; 25922 and &lt;em&gt;P. aeruginosa&lt;/em&gt; 10145. The bacteriostatic and bactericidal effects at concentrations as low as 0.015 µg/mL indicated the potent antibacterial activity of &lt;em&gt;O. ramonense&lt;/em&gt;. &lt;/p&gt;&lt;p&gt;&lt;strong&gt;Video Clip of Methodology:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Disc Diffusion method: 2 min 16 sec &lt;a href="https://www.youtube.com/v/HUZqSngRvmQ"&gt;Full Screen&lt;/a&gt; &lt;a href="https://www.youtube.com/watch?v=HUZqSngRvmQ"&gt;Alternate&lt;/a&gt;&lt;/p&gt;

Synthesis, Characterization, Modeling, and Antimicrobial Activity of FeIII, CoII, NiII, CuII, and ZnII Complexes Based on Tri‐substituted Imidazole Ligand

The reaction of the synthesized 2‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl) phenol, (HL) ligand with FeIII, CoII, NiII, CuII, and ZnII ions at room temperature resulted in the formation of the five complexes; [Fe(L)2(H2O)(Cl)]·2H2O and [M(L)2)]·nH2O [M = Co, Zn (n = 2), Ni, Cu (n = 1)]. The ligand and its complexes were characterized based on elemental analyses, spectral, magnetic and molar conductance measurements. The molecular and electronic structure of the ligand and its complexes was optimized theoretically and the quantum chemical parameters were calculated. The results revealed an interesting geometrical variation; octahedral for FeL, seesaw for CoL, distorted square planar for NiL and CuL, as well a tetrahedral arrangement for ZnL. The HL ligand and its metal complexes were screened against the growth of pathogenic bacteria [Escherichia coli (G–) and Bacillus cereus (G+)] and fungi (Aspergillus fumigatus) in terms of the minimum inhibitory concentration (MIC). The metal complexes showed high enhancement as antimicrobial candidates with lower MIC values compared with their parent ligand. Structure activity relationship formula was quantified by correlating the experimental MIC values with theoretical electronic chemical properties. Molecular docking of the complexes against CYP51B protein of A. fumigatus, the target enzyme for the antimicrobial reagents, was achieved to find the best orientation of the substrate, which would form a stable complex with overall minimum energy. The docking results enhanced the activity of the imidazole‐based complexes as promising antimicrobial candidates.

EVALUATION OF ANTIBACTERIAL AND HAEMOLYTIC ACTIVITY OF PHYTOCHEMICALS FROM FRESHWATER MICROALGA, EUGLENA VIRIDIS (EHREN)

Objective: The main aim of this research work was to evaluate the antibacterial and haemolytic activities of different extracts of Euglena viridis (E. viridis), a freshwater microalga.Methods: The solvent extraction has been followed by a preliminary screening of phytochemicals. The ethanolic extract, Eu(EtOH) was chromatographed on a silica gel column. The column was eluted with hexane and then with ethyl acetate/hexane mixtures of increasing polarity, 16 fractions (Ef1-Ef16) were collected and grouped according to their TLC (Thin layer chromatography). Antibacterial activities of different fractions of E. viridis against Pseudomonas putida (P. putida) ATCC49828, P. aeruginosa MTCC 35672, Aeromonas hydrophila (A. hydrophila) MTCC 646, ATCC 49140, eleven strains of Staphylococcus aureus (S. aureus) and thirteen strains of Flavobacterium columnare (F. columnare) was done using disc diffusion methods. Haemolytic activity was carried out by using blood agar plate method. The MIC (Minimum inhibitory concentration) values of active fractions were determined by the broth dilution method.Results: The results showed that the Eu(EtOH) poses significantly (p≤0.5) higher zone of inhibition (14.0±0.28, 13.5±0.28 mm) against FLV8 and FLV9 respectively. Three strains of Flavobacterium (FLV5, FLV6 and FLV10) were highly sensitive (zone size, 17 mm, 17.5 mm) towards 30% EA: Hex chromatographic eluents (Ef11) with lowest MIC values, e. i 60 µg and 30 µg respectively. Two chromatographic fractions, Ef11 and Ef13 were highly effective (zone size, 14.5 mm and 13.5 mm) against S. aureus (SA5) with lowest MIC value (60µg). Haemolytic activities of all the algal extracts were noticed that both Eu(EtOH) and methanolic extract, Eu(MeOH) of Euglena gives negative results.Conclusion: These findings suggest that the extract obtained from E. viridis have active substances contributing to the increasing antibacterial potential.

Urinary tract infections by multidrug resistant Acinetobacter species- A Retrospective Analysis

Abstract Background: Acinetobacter species have emerged as important cause of nosocomial infections like pneumonia and urinary tract infections. Acinetobacter species are known to be highly resistant to commonly used antimicrobial agents. SinceAcinetobacter species are ubiquitous and have tremendous colonizing capacity, it is difficult to explain the role of Acinetobacter acquisition in the ICU and medical wards. The objective of this study was to determine the frequency of urinary tract infection (UTI) caused by different Acinetobacter species in hospitalized patients and in the community and to analyze their antimicrobial susceptibility pattern. Materials and Methods: This is a retrospective analysisfrom January 2016 to December 2017. Urine samples collected in appropriate sterile manner were screened for polymorphonuclear leucocytes and bacteria by routine microscopic examination. This was followed by plating on MacConkey's agar and Blood agar. Isolated Acinetobacter strains which are oxidase negative and non-lactose fermenters from MacConkey's agar were identified with Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) to confirm the TM identification. Antibiotic susceptibility was performed by VitekCompact™ 2 (Biomeuriux, France) as per CLSI standards establishing MIC (Minimum Inhibitory Concentration). Results: Of the 429 isolates of Acinetobacterspecies from urinary tract, Acinetobacterbaumannii complex (78%) found to be the most common species followed by Acinetobacterjunii(10%) and Acinetobacterbaumannii(8%). Of the 334 (78%) isolates of Acinetobacterbaumannii complex from urinary tract, 73 (21.85%) isolates were resistant with doripenem, 62 (18.56%) with imipenem and 59 (17.66%) were resistant with meropenem with MIC values &gt;=8 μg/ml. The rest of the isolates like Acinetobacterjunii, Acinetobacterjohnsonii, andAcinetobacterlwoffiiare found to be more sensitive with carbapenems with lower MIC values. Discussion: The treatment of multidrug-resistant bacteria in hospitalized patients continues to be a challenge for the clinician's in routine practice. Acinetobacter baumannii complex has proven to be an important pathogen in health care associated infections with significant mortality and morbidity. The drug resistant nature of the pathogen and its unpredictable susceptibility patterns make empirical and therapeutic decisions even more difficult. Conclusion: A. baumanniiis an important opportunistic agent of nosocomial UTI, especially in patients with longer hospitalization, antibiotic exposure, urinary catheterization and decreased immunity. High antimicrobial resistance and patient co-morbidities limit therapeutic choices. Hence, alternative therapeutic options are urgently needed to treat a patient with A. baumanniiinfection.

Bacterial Factors That Predict Relapse after Tuberculosis Therapy

BackgroundApproximately 5% of patients with drug-susceptible tuberculosis have a relapse after 6 months of first-line therapy, as do approximately 20% of patients after 4 months of short-course therapy. We postulated that by analyzing pretreatment isolates of Mycobacterium tuberculosis obtained from patients who subsequently had a relapse or were cured, we could determine any correlations between the minimum inhibitory concentration (MIC) of a drug below the standard resistance breakpoint and the relapse risk after treatment.MethodsUsing data from the Tuberculosis Trials Consortium Study 22 (development cohort), we assessed relapse and cure isolates to determine the MIC values of isoniazid and rifampin that were below the standard resistance breakpoint (0.1 μg per milliliter for isoniazid and 1.0 μg per milliliter for rifampin). We combined this analysis with clinical, radiologic, and laboratory data to generate predictive relapse models, which we validated by analyzing data from the DMID 01-009 study (validation cohort).ResultsIn the development cohort, the mean (±SD) MIC of isoniazid below the breakpoint was 0.0334±0.0085 μg per milliliter in the relapse group and 0.0286±0.0092 μg per milliliter in the cure group, which represented a higher value in the relapse group by a factor of 1.17 (P=0.02). The corresponding MIC values of rifampin were 0.0695±0.0276 and 0.0453±0.0223 μg per milliliter, respectively, which represented a higher value in the relapse group by a factor of 1.53 (P<0.001). Higher MIC values remained associated with relapse in a multivariable analysis that included other significant between-group differences. In an analysis of receiver-operating-characteristic curves of relapse based on these MIC values, the area under the curve (AUC) was 0.779. In the development cohort, the AUC in a multivariable model that included MIC values was 0.875. In the validation cohort, the MIC values either alone or combined with other patient characteristics were also predictive of relapse, with AUC values of 0.964 and 0.929, respectively. The use of a model score for the MIC values of isoniazid and rifampin to achieve 75.0% sensitivity in cross-validation analysis predicted relapse with a specificity of 76.5% in the development cohort and a sensitivity of 70.0% and a specificity of 100% in the validation cohort.ConclusionsIn pretreatment isolates of M. tuberculosis with decrements of MIC values of isoniazid or rifampin below standard resistance breakpoints, higher MIC values were associated with a greater risk of relapse than lower MIC values. (Funded by the National Institute of Allergy and Infectious Diseases.)

Effect of Extracts of Capparis spinosa, Withania somnifera and Peganum harmala on Aspergillus flavus Growth and Expression of Major Genes in Aflatoxin Biosynthetic Pathway

Background: Aflatoxins, a polyketide group derived from furanocoumarins, are highly toxic carcinogens produced by Aspergillus flavus and other closely related species. Objectives: In this research, the effects of Capparis spinosa, Withania somnifera, and Peganum harmala extracts on A. flavus growth and the expression of some major genes in aflatoxin biosynthetic pathway were investigated. Methods: Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were measured and the expression of aflQ, aflO, aflS, and aflR genes was evaluated by using quantitative real-time polymerase chain reaction (qRT-PCR) technique. Results: Capparis spinosa extract had the lowest MIC value (200 mg/mL) and the extracts of W. somnifera and P. harmala had the highest MIC value (400 mg/mL). The extracts of W. somnifera and P. harmala had no fungicidal activity, and the C. spinosa extract had the lowest MFC value (400 mg/mL) and had the highest fungicidal effect on A. flavus. The expression of aflQ, aflO, aflS, and aflR genes was significantly decreased by the C. spinosa extract. Conclusions: In general, the C. spinosa extract could have fungicidal and inhibitory effects on A. flavus and reduce expression of major genes in the aflatoxin biosynthetic pathway.

In Vitro Activity of Tedizolid, Dalbavancin, and Ceftobiprole Against Clostridium difficile.

Background: Clostridium difficile (C. difficile) is a major nosocomial pathogen that colonizes in the human gut. Recently, the U.S. FDA approved three new antimicrobial agents against gram-positive bacteria: Tedizolid, Dalbavancin, and Ceftobiprole. The efficacy of these antibiotics for treatment of C. difficile infection has not been thoroughly examined. The current study aimed to examine the in vitro activity of these antibiotics against C. difficile. In addition, to compare between Dalbavancin and Ceftobiprole to antibiotics from the same class: Vancomycin and Ceftriaxone, respectively.Methods: Eighty-four C. difficile isolates were tested for susceptibility to Tedizolid, Dalbavancin, Ceftobiprole, Vancomycin, and Ceftriaxone by Etest technique in order to determine the minimum inhibitory concentration (MIC).Results: Upon comparison of the novel antibiotic agents, Dalbavancin demonstrated the lowest MIC values and ceftobiprole the highest at MIC50 (0.016, 0.38, and 1.5 μg/mL, for Dalbavancin, Tedizolid, and Ceftobiprole, respectively) and MIC90 (0.03, 0.78, and 3.17 μg/mL, respectively). Dalbavancin demonstrated significantly lower MIC50 and MIC90 values compared to Vancomycin (0.016 vs. 0.38 and 0.03 vs. 3.5, respectively) (p < 0.001) and ceftobiprole had significantly lower MIC values compare to ceftriaxone (1.5 vs. 32 and 3.17 vs. 28.8, respectively) (p < 0.001).Conclusion: Dalbavancin and Tedizolid may play a role as potential therapeutic agents for treatment of C. difficile infection. Examination of antibiotic effect on the intestinal microbiome and clinical trials are needed for more accurate results.

Antibacterial activity of Rosmarinus officinalis L. and Thymus vulgaris L. essential oils and their combination against food-borne pathogens and spoilage bacteria in ready-to-eat vegetables

The antibacterial activity of Rosmarinus officinalis L. and Thymus vulgaris L. essential oils (EOs), and their combination against food-borne and spoilage bacteria (Listeria monocytogenes, Salmonella enteritidis, Yersinia enterocolitica, Escherichia coli and Pseudomonas spp.) was determined. The EOs inhibitory effect was evaluated both in vitro by using the disk diffusion assay and the minimum inhibitory concentration (MIC) determination, and on food by using an artificially contaminated ready-to-eat (RTE) vegetables. The results showed that the lowest MIC values were obtained with R. officinalis and T. vulgaris EOs against E. coli (4 and 8 μL/mL, respectively). The incorporation of the EOs alone or their combination in RTE vegetables reduced the viable counts of all the tested strains. Lastly, in the on food study we simulated the worst hygienic conditions, obtaining results that can be considered a warranty of safety.