scholarly journals Analysis of the Mutant Selection Window and Killing of Mycoplasma hyopneumoniae for Doxycycline, Tylosin, Danofloxacin, Tiamulin, and Valnemulin

2019 ◽  
Author(s):  
Zilong Huang ◽  
Chunxiao Mao ◽  
Yanzhe Wei ◽  
Xiaoyan Gu ◽  
Qinren Cai ◽  
...  
Keyword(s):  
Mycoplasma Hyopneumoniae ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Mutant Selection ◽  
Selection Window ◽  
Mutant Prevention Concentration ◽  
Agar Dilution ◽  
Minimal Concentration ◽  
Conventional Antibiotics ◽  
Microdilution Broth

AbstractMycoplasma hyopneumoniae is the major pathogenic microorganism causing enzootic pneumonia in pigs. With increasing resistance of M. hyopneumoniae to conventional antibiotics, treatment is becoming complicated. Herein, we investigated the mutant selection window (MSW) of doxycycline, tylosin, danofloxacin, tiamulin, and valnemulin for treating M. hyopneumoniae strain (ATCC 25934) to determine the likelihood of promoting resistance with continued use of these antibiotics. Minimum inhibitory concentration (MIC) values against M. hyopneumoniae were determined for each antimicrobial agent and ranged from 105 colony-forming units (CFU)/mL to 109 CFU/mL based on microdilution broth and agar dilution methods. The minimal concentration inhibiting colony formation by 99% (MIC99) and the mutant prevention concentration (MPC) were determined by the agar dilution method with three inoculum sizes. Antimicrobial killing was determined based on MIC99 and MPC values for all five agents. MIC values ranged from 0.001 to 0.25 μg/mL based on the microdilution broth method, and from 0.008 to 1.0 μg/mL based on the agar dilution method. MPC values ranged from 0.0016 to 10.24 μg/mL. MPC/MIC99 values were ordered tylosin >doxycycline >danofloxacin >tiamulin >valnemulin. MPC achieved better bactericidal action than MIC99. Based on pharmacodynamic analyses, danofloxacin, tylosin, and doxycycline are more likely to select resistant mutants than tiamulin and valnemulin.

scholarly journals Evaluation of Fluoroquinolone Resistance in Clinical Avian Pathogenic Escherichia coli Isolates from Flanders (Belgium)

Antibiotics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 800
Author(s):  
Robin Temmerman ◽  
An Garmyn ◽  
Gunther Antonissen ◽  
Gerty Vanantwerpen ◽  
Mia Vanrobaeys ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rapid Development ◽  
Fluoroquinolone Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Avian Pathogenic Escherichia Coli ◽  
Topoisomerase Iv ◽  
Mutant Selection ◽  
Pathogenic Escherichia Coli ◽  
Mutant Prevention Concentration

Fluoroquinolones are frequently used antimicrobials for the treatment of avian pathogenic Escherichia coli (APEC) infections. However, rapid development and selection of resistance to this class of antimicrobial drugs is a significant problem. The aim of this study was to investigate the occurrence and mechanisms of antimicrobial resistance against enrofloxacin (ENRO) in APEC strains in Flanders, Belgium. One hundred and twenty-five APEC strains from broilers with clinical colibacillosis were collected in Flanders from November 2017 to June 2018. The minimum inhibitory concentration (MIC) of all strains and the mutant prevention concentration (MPC) of a sample of sensitive isolates were determined using a commercial gradient strip test and via the agar dilution method, respectively. Non-wild type (NWT) isolates were further characterized using polymerase chain reaction (PCR), gel electrophoresis and gene sequencing. Forty percent of the APEC strains were NWT according to the epidemiological cut-off (ECOFF) measure (MIC > 0.125 μg/mL). With respect to clinical breakpoints, 21% were clinically intermediate (0.5 ≤ MIC ≤ 1 μg/mL) and 10% were clinically resistant (MIC ≥ 2). The MPC values of the tested strains ranged from 0.064 to 1 μg/mL, resulting in MPC/MIC ratios varying from 4 to 32. The majority (92%) of the NWT strains carried one or two mutations in gyrA. Less than a quarter (22%) manifested amino acid substitutions in the topoisomerase IV parC subunit. Only three of the NWT strains carried a mutation in parE. Plasmid mediated quinolone resistance (PMQR) associated genes were detected in 18% of the NWT strains. In contrast to the relatively large number of NWT strains, only a small percentage of APEC isolates was considered clinically resistant. The most common MPC value for sensitive strains was 0.125 μg/mL. Some isolates showed higher values, producing wide mutant selection windows (MSW). Chromosomal mutations in DNA gyrase and topoisomerase IV were confirmed as the main source of decreased antimicrobial fluoroquinolone susceptibility, de-emphasizing the role of PMQR mechanisms.

scholarly journals Evaluation of the Antimicrobial Activity of Some Components of the Essential Oils of Plants Used in the Traditional Medicine of the Tehuacán-Cuicatlán Valley, Puebla, México

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 295
Author(s):  
Sebastián Candelaria-Dueñas ◽  
Rocío Serrano-Parrales ◽  
Marisol Ávila-Romero ◽  
Samuel Meraz-Martínez ◽  
Julieta Orozco-Martínez ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Essential Oils ◽  
Qualitative Evaluation ◽  
Bactericidal Effect ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Diffusion Technique ◽  
Agar Dilution

In Tehuacán-Cuicatlán valley (Mexico), studies have been carried out on the essential oils of medicinal plants with antimicrobial activity and it was found that they present compounds in common such as: α-pinene, β-pinene, carvacrol, eugenol, limonene, myrcene, ocimene, cineole, methyl salicylate, farnesene, and thymol. The goal of this study was to assess the antimicrobial activity of essential oils’ compounds. The qualitative evaluation was carried out by the Kirby Baüer agar diffusion technique in Gram-positive bacteria (11 strains), Gram-negative bacteria (18 strains), and yeasts (8 strains). For the determination of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), the agar dilution method was used. All the evaluated compounds presented antimicrobial activity. The compounds eugenol and carvacrol showed the largest inhibition zones. Regarding yeasts, the compounds ocimene, cineole, and farnesene did not show any activity. The compounds eugenol, carvacrol, and thymol presented the lowest MIC; bactericidal effect was observed at MIC level for S. aureus 75MR, E. coli 128 MR, and C albicans CUSI, for different compounds, eugenol, carvacrol, and thymol. Finally, this study shows that the essential oils of plants used by the population of Tehuacán-Cuicatlán valley share compounds and some of them have antibacterial and fungicidal activity.

scholarly journals Antibiotic sensitivities of Neisseria meningitidis isolates from patients and carriers in Greece

1992 ◽  
Vol 108 (3) ◽  
pp. 449-455 ◽  
Author(s):  
G. Tzanakaki ◽  
C. C. Blackwell ◽  
J. Kremastinou ◽  
C. Kallergi ◽  
G. Kouppari ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
School Children ◽  
Penicillin G ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Southern Europe ◽  
Agar Dilution ◽  
Of Greece

SUMMARYUsage of antibiotics in southern Europe is less well regulated than in northern countries. The proportion (48%) of meningococci in Spain insensitive to penicillin (MIC ≥ 0·1 mg/l) prompted this investigation of antibiotic sensitivities of isolates from Greek patients with meningitis (31) and carriers (47 school-children and 472 recruits). The agar dilution method was used to determine MIC to penicillin G (PN), sulphamethoxazole (SU), rifampicin (RF), cefaclor (CF) and ciprofloxacin (CP).The proportion of isolates insensitive to PN was 48% for isolates from patients, 19% from school-children and 36·6% from recruits. Resistance to SU (MIC ≥ 16 mg/l) was found in 16% of those from patients, 10·6% from children and 40% from recruits. None of the isolates from patients was resistant to RF (≥ 1 mg/l) but 6% of those from carriers were. Resistance to CF (≥ 4 mg/l) was found in 9·2% of patient isolates, 6·4% from children and 23·7% from recruits. All isolates except one were sensitive to CP (MIC range < 0·0015–0·125 mg/l).Resistances to PN, SU and RF were analysed by serogroup, serotype and subtype of the bacteria. The proportion of resistant isolates showed some variation between different areas of Greece, but it was not statistically significant.

scholarly journals Prevalence and characterization of extended spectrum beta-lactamase-producing Enterobacter cloacae strains in Algeria

2013 ◽  
Vol 7 (11) ◽  
pp. 804-811 ◽  
Author(s):  
Sabrina Nedjai ◽  
Abouddihaj Barguigua ◽  
Nassima Djahmi ◽  
Loubna Jamali ◽  
Khalid Zerouali ◽  
...  
Keyword(s):  
Enterobacter Cloacae ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Extended Spectrum Beta Lactamase ◽  
Agar Dilution ◽  
Synergy Test ◽  
High Level ◽  
Genomic Typing ◽  
Microbiological Data

Introduction: Expended spectrum β-lactamase (ESBL)-producing Enterobacter cloacae is an important nosocomial pathogen. In this study, the prevalence and the molecular epidemiology of ESBL producing E. cloacae strains isolated from various hospitals in Annaba, Algeria were investigated. Methodology: The study involved 63 isolates of E. cloacae obtained during 2009 at the four hospitals in Annaba. The detection of ESBL was performed using the double-disk synergy test and the combined disk test. Minimum inhibitory concentrations (MICs) were determined using the agar dilution method. The presence of blaCTX-M, blaSHV, blaTEM, and blaDHA β-lactamase genes was evaluated by PCR, and genomic typing was determined by pulsed-field gel electrophoresis (PFGE) analysis. The clinical and microbiological data were entered into the EpiI Info database. Results: Thirty isolates (47.6%) had an ESBL phenotype. BlaCTX-M group1 (76%); blaTEM (70%) were the most prevalent, followed by blaDHA (16.6%) and blaSHV (10%). Eighteen strains expressed at least two bla genes. MICs revealed a high level of resistance to cefotaxime, ceftazidime, and cefepime.  PFGE revealed an epidemic clonal dissemination of these isolates. Various risk factors associated with the occurrence of ESBL-producing E. cloacae were detected. Conclusions: A higher frequency of ESBL-producing isolates and a diversity of β-lactamases were detected among ESBL-producing E. cloacae; these resulted from an epidemic clonal dissemination and high transference of ESBL genes between bacteria in hospital settings. Strict measures will be required to control the further spread of these pathogens in hospital settings.

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 Antimicrobial activity of honeys from two stingless honeybee species and Apis mellifera (Hymenoptera: Apidae) against pathogenic microorganisms

2014 ◽  
Vol 44 (2) ◽  
pp. 287-290 ◽  
Author(s):  
Carolinie Batista Nobre da Cruz ◽  
Fabio Alessandro Pieri ◽  
Gislene Almeida Carvalho-Zilse ◽  
Patrícia Puccinelli Orlandi ◽  
Carlos Gustavo Nunes-Silva ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Apis Mellifera ◽  
Antimicrobial Agents ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Therapeutic Approaches ◽  
E Coli ◽  
Agar Dilution ◽  
Amazonas State

Honeys are described possessing different properties including antimicrobial. Many studies have presented this activity of honeys produced by Apis mellifera bees, however studies including activities of stingless bees honeys are scarce. The aim of this study was to compare the antimicrobial activity of honeys collected in the Amazonas State from Melipona compressipes, Melipona seminigra and Apis mellifera against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Chromobacterium violaceum, and Candida albicans. Minimum inhibitory concentrations were determined using the agar dilution method with Müller-Hinton agar (for bacteria) or Saboraud agar (for yeast). Staphylococcus aureus and E. faecalis were inhibited by all honeys at concentrations below 12%, while E. coli and C. violaceum were inhibited by stingless bee honeys at concentrations between 10 and 20%. A. mellifera honey inhibited E. coli at a concentration of 7% and Candida violaceum at 0.7%. C. albicans were inhibited only with honey concentrations between 30 and 40%. All examined honey had antimicrobial activity against the tested pathogens, thus serving as potential antimicrobial agents for several therapeutic approaches.

scholarly journals Drug resistance of yeasts isolated from oropharyngeal candidiasis in aids patients

1998 ◽  
Vol 29 (4) ◽  
pp. 271-275
Author(s):  
Maria do Rosário Rodrigues Silva ◽  
Claudete Rodrigues de Paula ◽  
Soraya Cristina Silva ◽  
Théo Rodrigues Costa ◽  
Márcio Rodrigues Costa
Keyword(s):  
Amphotericin B ◽  
High Frequency ◽  
Inhibitory Concentration ◽  
Serum Levels ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Oropharyngeal Candidiasis ◽  
Candida Spp ◽  
Aids Patients ◽  
Agar Dilution

Candida spp was isolated from 59 (68.60%) out of eighty six samples of oral mucosa of AIDS patients. The identification, based or the production of a germ tube and chlamydospores, and on the assimilation and fermentation of carbohydrates, revealed 52 strains (88.13%) of C. albicans, 4 (6.77%) of C. tropicalis and 3 (5.08%) of C. krusei. The susceptibility of these strains to amphotericin B, flucytosine, itraconazole, fluconazole and ketoconazole was determined using the agar dilution method. Comparing the minimum inhibitory concentration values found in the susceptibility test with the serum levels achieved by these drugs, only 8.47% and 5.08% of the yeasts strains proved to be resistant to amphotericin B and flucitosyne, respectively. A high frequency of strains resistant to azole derivatives (25.42%, to itraconazole, 45.76%, to ketoconazole and 66.10% to fluconazole) was observed.

scholarly journals Determination of MIC, MPC, and MSW of Ilex paraguariensis Against Non-Typhoidal Salmonella with Identification of the Mechanisms of Resistance and Pathogenicity Factors

2020 ◽  
Author(s):  
Khaled El Khatib ◽  
Ribal Aby Hadeer ◽  
Anis Saad ◽  
Aline Kalaydjian ◽  
Elie Fayad ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Concentration ◽  
Ilex Paraguariensis ◽  
Salmonella Spp ◽  
Mutant Selection ◽  
Selection Window ◽  
Mutant Prevention Concentration ◽  
Resistance Patterns ◽  
Different Strains

Abstract Objective: This study investigated the antibacterial activity of Ilex paraguariensis extracts against 32 different strains of non-typhoidal Salmonella (NTS) through the determination of the Minimum Inhibitory Concentration (MIC), Mutant Prevention Concentration (MPC), Mutant Selection Window (MSW), and the detection of virulence genes by multiplex PCR assays. Results: The MIC values of Ilex paraguariensis against Salmonella spp. strains varied between 0.78 mg/ml and 6.25 mg/ml with a MIC 90 of 3.12 mg/ml. The highest MPC in this study was 48 mg/ml yielding a Mutant Selection Window of 41.75 mg/ml. The MSW values of the remaining strains varied between 1.56 and 8.87 mg/ml. Genes of pathogenicity detected in Salmonella spp. isolates were most commonly the stn, sdiA, invA, sopB, invH, and sopE genes. The antibacterial activity of Yerba Mate extracts was not affected by the antimicrobial resistance patterns or pathogenicity genes expressed. More work is needed to identify the active antibacterial compound(s) responsible for the antibacterial activity.

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