scholarly journals Isolates of Clostridium perfringens recovered from Costa Rican patients with antibiotic-associated diarrhoea are mostly enterotoxin-negative and susceptible to first-choice antimicrobials

2008 ◽  
Vol 57 (3) ◽  
pp. 343-347 ◽  
Author(s):  
Natassia Camacho ◽  
Carlos Espinoza ◽  
César Rodríguez ◽  
Evelyn Rodríguez
Keyword(s):  
Clostridium Perfringens ◽  
Sampling Period ◽  
Costa Rican ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
First Choice ◽  
Low Incidence ◽  
Pcr Targeting ◽  
Antibiotic Associated Diarrhoea

To assess the prevalence of enterotoxigenic Clostridium perfringens among adults suffering from antibiotic-associated diarrhoea in a Costa Rican hospital, faecal samples were analysed from 104 patients by a cultivation approach. The 29 strains obtained, which accounted for an isolation frequency of 28 %, were genotyped and investigated with regard to their in vitro susceptibility to penicillin, imipenem, cefotaxime, chloramphenicol and metronidazole using an agar-dilution method. A multiplex PCR for detection of the toxins α, β and ϵ predictably classified all faecal isolates as biotype A. An agglutination assay revealed that only one isolate synthesized detectable amounts of enterotoxin (detection rate 3 %). This result was confirmed by a PCR targeting the cpe gene. The spores of the only CPE+ isolate did not germinate after incubation for 30 min at temperatures above 80 °C. Most isolates were susceptible to first-choice antimicrobials. However, unusual MICs for penicillin (16 μg ml−1) and metronidazole (512 μg ml−1) were detected in one and three isolates, respectively. The low incidence of enterotoxigenic strains suggests that C. perfringens was not a major primary cause of antibiotic-associated diarrhoea in this hospital during the sampling period.

scholarly journals e-Pharmacophore model-guided design of potential DprE1 inhibitors: synthesis, in vitro antitubercular assay and molecular modelling studies

2021 ◽  
Author(s):  
Avinash Kumar ◽  
Revathi Rajappan ◽  
Suvarna G. Kini ◽  
Ekta Rathi ◽  
Sriram Dharmarajan ◽  
...  
Keyword(s):  
Pharmacophore Model ◽  
Antitubercular Activity ◽  
Stable Complex ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Standard Drug ◽  
Docking Score ◽  
Mycobacterium Tuberculosis H37rv ◽  
Cytotoxicity Studies

AbstractTuberculosis continues to wreak havoc worldwide and caused around 1.4 million deaths in 2019. Hence, in our pursuit of developing novel antitubercular compounds, we are reporting the e-Pharmacophore-based design of DprE1 (decaprenylphosphoryl-ribose 2′-oxidase) inhibitors. In the present work, we have developed a four-feature e-Pharmacophore model based on the receptor–ligand cavity of DprE1 protein (PDB ID 4P8C) and mapped our previous reported library of compounds against it. The compounds were ranked on phase screen score, and the insights obtained from their alignment were used to design some novel compounds. The designed compounds were docked with DprE1 protein in extra-precision mode using Glide module of Maestro, Schrodinger. Some derivatives like B1, B2, B4, B5 and B12 showed comparable docking score (docking score > − 6.0) with respect to the co-crystallized ligand. The designed compounds were synthesized and characterized. In vitro antitubercular activity was carried out on Mycobacterium tuberculosis H37Rv (ATCC27294) strain using the agar dilution method, and minimum inhibitory concentration (MIC) was determined. The compound B12 showed a MIC value of 1.56 μg/ml which was better than the standard drug ethambutol (3.125 μg/ml). Compounds B7 and B11 were found to be equipotent with ethambutol. Cytotoxicity studies against Vero cell lines proved that these compounds were non-cytotoxic. Molecular dynamic simulation study also suggests that compound B12 will form a stable complex with DprE1 protein and will show the crucial H-bond interaction with LYS418 residue. Further in vitro enzyme inhibition studies are required to validate these findings.

scholarly journals Antifungal and Antibacterial Metabolites from a French Poplar Type Propolis

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Séverine Boisard ◽  
Anne-Marie Le Ray ◽  
Anne Landreau ◽  
Marie Kempf ◽  
Viviane Cassisa ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Antifungal Activity ◽  
Antimicrobial Effect ◽  
Antibacterial Activities ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gram Positive ◽  
Weak Activity ◽  
Agar Dilution

During this study, thein vitroantifungal and antibacterial activities of different extracts (aqueous and organic) obtained from a French propolis batch were evaluated. Antifungal activity was evaluated by broth microdilution on three pathogenic strains:Candida albicans, C. glabrata, andAspergillus fumigatus. Antibacterial activity was assayed using agar dilution method on 36 Gram-negative and Gram-positive strains includingStaphylococcus aureus. Organic extracts showed a significant antifungal activity againstC. albicansandC. glabrata(MIC80between 16 and 31 µg/mL) but only a weak activity towardsA. fumigatus(MIC80= 250 µg/mL). DCM based extracts exhibited a selective Gram-positive antibacterial activity, especially againstS. aureus(SA) and several of its methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) strains (MIC10030–97 µg/mL). A new and active derivative of catechin was also identified whereas a synergistic antimicrobial effect was noticed during this study.

scholarly journals IDENTIFICATION AND DETECTION OF BIOFILM PRODUCING STAPHYLOCOCCUS AUREUS AND ITS ANTIBIOGRAM ACTIVITIES

2021 ◽  
pp. 150-156
Author(s):  
SAPANA SHARMA ◽  
UPASHANA BHANDARI ◽  
YOGESH OLI ◽  
GANESH BHANDARI ◽  
SUNITA BISTA ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Disk Diffusion ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Methicillin Resistant ◽  
Clinical Specimens ◽  
Biofilm Production ◽  
Diffusion Technique ◽  
Almost All

Objectives: The main aim of this work is to determine the antibiogram profile of biofilm-producing Staphylococcus aureus from various clinical specimens of the patients. Methods: Various bacterial cultures of non-repeated clinical specimens from a total of 3388 patients were determined using standard microbiological and biochemical methods. Results: Out of 3388 only 604 (17.02%) displayed growth positive. A total of 65 (51.58%) S. aureus isolates were recovered, 25 (38.46%) were identified as methicillin-resistant S. aureus (MRSA) by Cefoxitin (30 μg) disk diffusion technique, of which majority were from pus/wound swab 22 (37.29%). The antibiogram of the isolates was analyzed by Kirby-Bauer disk diffusion technique analyzing Linezolid to be the most effective drug with susceptibility of 100% to both MRSA and methicillin-sensitive S. aureus, followed by vancomycin, tigecycline, and tetracycline. In vitro biofilm production by tissue culture plate (TCP) and Congo red agar method detected 52 (80%) and 25 (38.46%) as biofilm producers, respectively. TCP identified 2 (3.07%), 7 (10.76%), and 44 (67.69%) as strongly, moderately, and weakly adherent. About 30.7% of MRSA obtained were positive biofilm producers. The minimum inhibitory concentration value of Oxacillin for S. aureus by agar dilution method ranged from 0.025 μg/mL to 128 μg/mL. Conclusion: This study shows that biofilm production was more in methicillin-resistant strains and displayed a high degree of resistance to almost all groups of antibiotics.

Ginseng aqueous extract attenuates the production of virulence factors, stimulates twitching and adhesion, and eradicates biofilms of Pseudomonas aeruginosa

2011 ◽  
Vol 89 (6) ◽  
pp. 419-427 ◽  
Author(s):  
Misagh Alipour ◽  
Abdelwahab Omri ◽  
Zacharias E. Suntres
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Aqueous Extract ◽  
North American ◽  
American Ginseng ◽  
Antimicrobial Activities ◽  
Live Cells ◽  
Dilution Method ◽  
Agar Dilution Method

This study was carried out to examine the antimicrobial activity of the aqueous extract of Panax quinquefolius from North American ginseng (NAGE) root against Pseudomonas aeruginosa . The minimum inhibitory concentrations of reference and clinical isolates of Pseudomonas aeruginosa were measured by a standard agar-dilution method. At subinhibitory NAGE concentrations, the secretion of virulence factors, motility on agar, and adhesion to 96-well microplates were studied on the nonmucoid Pseudomonas aeruginosa O1 strain. At suprainhibitory concentrations, the activity of NAGE against mature biofilm complexes formed in the Calgary Biofilm Device and the Stovall flow cell were assessed. NAGE possessed an antibacterial activity against all the Pseudomonas aeruginosa strains at 1.25%–2.5% w/v. NAGE also significantly attenuated pyocyanin, pyoverdine, and lipase concentrations, stimulated twitching, and attenuated swarming and swimming motility. At 1.25% w/v, NAGE augmented adhesion, and at 5% w/v detached 1-day-old biofilms in microplates. The extract also eradicated 6-day-old mature biofilms (5% w/v), and fluorescence microscopy displayed a reduction of live cells and biofilm complexes compared with nontreated biofilms. These data suggest that the aqueous extract from North American ginseng possesses antimicrobial activities in vitro.

scholarly journals Radiometric studies of mycobacterium tuberculosis

1987 ◽  
Vol 29 (1) ◽  
pp. 18-25
Author(s):  
Edwaldo E. Camargo ◽  
Judith A. Kertcher ◽  
Marianne F. Chen ◽  
Patricia Charache ◽  
Henry N. Wagner Jr
Keyword(s):  
Palmitic Acid ◽  
Lauric Acid ◽  
Bacterial Suspension ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Experimental Conditions ◽  
Vitro Assay ◽  
Minimal Inhibitory Concentrations ◽  
Different Strains

An in vitro assay system that included automated radiometric quantification of 14CO2 released as a result of oxidation of 14C- substrates was applied for studying the metabolic activity of M. tuberculosis under various experimental conditions. These experiments included the study of a) mtabolic pathways, b) detection times for various inoculum sizes, c) effect of filtration on reproducibility of results, d) influence of stress environment e) minimal inhibitory concentrations for isoniazid, streptomycin, ethambutol and rifampin, and f) generation times of M. tuberculosis and M. bovis. These organisms were found to metabolize 14C-for-mate, (U-14C) acetate, (U-14C) glycerol, (1-14C) palmitic acid, 1-14C) lauric acid, (U-14C) L-malic acid, (U-14C) D-glucose, and (U-14C) D-glucose, but not (1-14C) L-glucose, (U-14C) glycine, or (U-14C) pyruvate to 14CO2. By using either 14C-for-mate, (1-14C) palmitic acid, or (1-14C) lauric acid, 10(7) organisms/vial could be detected within 24 48 hours and as few as 10 organisms/vial within 16-20 days. Reproducible results could be obtained without filtering the bacterial suspension, provided that the organisms were grown in liquid 7H9 medium with 0.05% polysorbate 80 and homogenized prior to the study. Drugs that block protein synthesis were found to have lower minimal inhibitory concentrations with the radiometric method when compared to the conventional agar dilution method. The mean generation time obtained for M. bovis and different strains of M. tuberculosis with various substrates was 9 ± 1 hours.

scholarly journals In Vitro Antifungal Activity of Polysulfides-Rich Essential Oil of Ferula Latisecta Fruits against Human Pathogenic Dermatophytes

2008 ◽  
Vol 3 (9) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Mehrdad Iranshahi ◽  
Abdolmajid Fata ◽  
Bahareh Emami ◽  
Bibi Mohadeseh Jalalzadeh Shahri ◽  
Bibi Sedigheh Fazly Bazzaz
Keyword(s):  
Antifungal Activity ◽  
Essential Oil ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution ◽  
Sulfur Containing ◽  
Type Strains ◽  
In Vitro Antifungal Activity

The increase in dermatophytoses and the fact that some patients do not respond well to therapy make it necessary to find new antifungal agents. As part of our ongoing studies on medicinal plants from Iran, we studied antidermatophytic activities of Ferula latisecta essential oil, which had shown considerable antifungal activity in preliminary antimicrobial screening. Antifungal activity was evaluated by determination of MIC values using the agar dilution method on type strains of Candida albicans and dermatophytes. The composition of the oil was characterized by GC and GC/MS analyses. The essential oil was rich in polysulfides (75.2%) and exhibited good activity against Trichophyton rubrum and T. verrucosom for about three weeks, with a MIC value 96 μg/mL. The oil showed antifungal activity, especially against dermatophytes, and the activity is probably related to the sulfur-containing components of the oil. This study has identified that the polysulfides-rich essential oil of Ferula latisecta fruits has activity against a range of human pathogenic dermatophytes, justifying future clinical trials to validate its use as a therapeutic alternative for dermatophytosis.

scholarly journals In Vitro Activities of Garenoxacin (BMS-284756) against 170 Clinical Isolates of Nine Pasteurella Species

2002 ◽  
Vol 46 (9) ◽  
pp. 3068-3070 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
C. Vreni Merriam ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
...  
Keyword(s):  
Pasteurella Multocida ◽  
Active Agent ◽  
Culture Collection ◽  
Clinical Isolates ◽  
American Type Culture Collection ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution

ABSTRACT The in vitro susceptibilities of 170 clinical isolates plus 12 American Type Culture Collection strains of Pasteurella species comprising nine species and three Pasteurella multocida subspecies were studied by an agar dilution method. Garenoxacin (BMS-284756), a new des-fluoro(6) quinolone, was active at ≤0.06 μg/ml against all isolates, including four β-lactamase-producing strains, with >90% of the strains susceptible to ≤0.008 μg/ml. Garenoxacin was generally 1 to 2 dilutions more active than levofloxacin and moxifloxacin and was the most active agent tested. Cefoxitin required 1 μg/ml for inhibition of 51 of 182 (29%) of strains, and 3 strains (also β-lactamase producers) were resistant to doxycycline.

In vitro synergy testing of macrolide-quinolone combinations against 41 clinical isolates of Legionella.

1996 ◽  
Vol 40 (6) ◽  
pp. 1419-1421 ◽  
Author(s):  
S J Martin ◽  
S L Pendland ◽  
C Chen ◽  
P Schreckenberger ◽  
L H Danziger
Keyword(s):  
Yeast Extract ◽  
Antimicrobial Therapy ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution ◽  
Legionella Species ◽  
Checkerboard Assay ◽  
Synergy Testing

Combination antimicrobial therapy against Legionella species has not been well studied. Several quinolones have activity against Legionella strains, which prompted this in vitro search for a synergistic combination with the macrolides. By a checkerboard assay, erythromycin, clarithromycin, and azithromycin, each in combination with ciprofloxacin and levofloxacin, were tested for synergy against 46 isolates of Legionella. The agar dilution method was employed using buffered charcoal-yeast extract media. A final inoculum of 10(4) CFU per spot was prepared from 24-h growth of each isolate. Plates were incubated at 35 degrees C for 48 h. Synergy, partial synergy, additive effect, or indifference was observed for all combinations of antibiotics tested. There was no antagonism observed. Synergy occurred to a significantly greater extent for the clarithromycin-levofloxacin (P = 0.0001) and azithromycin-levofloxacin (P = 0.003) combinations versus erythromycin-levofloxacin. The azithromycin-ciprofloxacin combination demonstrated significantly greater synergy than did either erythromycin-ciprofloxacin (P = 0.003) or clarithromycin-ciprofloxacin (P = 0.001). The newer macrolides clarithromycin and azithromycin may be more active in combination with a fluoroquinolone than is erythromycin.

scholarly journals In VitroActivities of Tedizolid and Linezolid against Gram-Positive Cocci Associated with Acute Bacterial Skin and Skin Structure Infections and Pneumonia

2015 ◽  
Vol 59 (10) ◽  
pp. 6262-6265 ◽  
Author(s):  
Ko-Hung Chen ◽  
Yu-Tsung Huang ◽  
Chun-Hsing Liao ◽  
Wang-Hui Sheng ◽  
Po-Ren Hsueh
Keyword(s):  
Staphylococcus Aureus ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gram Positive ◽  
Content Type ◽  
Skin Structure ◽  
Streptococcus Anginosus ◽  
Wide Range ◽  
Gram Positive Cocci

ABSTRACTTedizolid is a novel, expanded-spectrum oxazolidinone with potent activity against a wide range of Gram-positive pathogens. A total of 425 isolates of Gram-positive bacteria were obtained consecutively from patients with acute bacterial skin and skin structure infections (ABSSSIs) or pneumonia. These isolates included methicillin-susceptibleStaphylococcus aureus(MSSA) (n= 100), methicillin-resistantStaphylococcus aureus(MRSA) (n= 100),Streptococcus pyogenes(n= 50),Streptococcus agalactiae(n= 50),Streptococcus anginosusgroup (n= 75),Enterococcus faecalis(n= 50), and vancomycin-resistant enterococci (VRE) (Enterococcus faecium) (n= 50). The MICs of tedizolid and linezolid were determined by the agar dilution method. Tedizolid exhibited betterin vitroactivities than linezolid against MSSA (MIC90s, 0.5 versus 2 μg/ml), MRSA (MIC90s, 0.5 versus 2 μg/ml),S. pyogenes(MIC90s, 0.5 versus 2 μg/ml),S. agalactiae(MIC90s, 0.5 versus 2 μg/ml),Streptococcus anginosusgroup (MIC90s, 0.5 versus 2 μg/ml),E. faecalis(MIC90s, 0.5 versus 2 μg/ml), and VRE (MIC90s, 0.5 versus 2 μg/ml). The tedizolid MICs againstE. faecalis(n= 3) and VRE (n= 2) intermediate to linezolid (MICs, 4 μg/ml) were 1 μg/ml and 0.5 μg/ml, respectively. The tedizolid MIC90s against S. anginosus,S. constellatus, andS. intermediuswere 0.5, 1, and 0.5 μg/ml, respectively, and the rates of susceptibility based on the U.S. FDA MIC interpretive breakpoints to the isolates were 16%, 28%, and 72%, respectively. Tedizolid exhibited 2- to 4-fold betterin vitroactivities than linezolid against a variety of Gram-positive cocci associated with ABSSSIs and pneumonia. The lower susceptibilities of tedizolid against isolates ofS. anginosusandS. constellatusthan against those ofS. intermediusin Taiwan were noted.

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