scholarly journals In Vitro Activity of Trovafloxacin against Bacteroides fragilis in Mixed Culture with either Escherichia coli or a Vancomycin- Resistant Strain of Enterococcus faecium Determined by an Anaerobic Time-Kill Technique

2001 ◽  
Vol 45 (1) ◽  
pp. 243-251 ◽  
Author(s):  
Lorna E. T. Stearne ◽  
Clarissa Kooi ◽  
Wil H. F. Goessens ◽  
Irma A. J. M. Bakker-Woudenberg ◽  
Inge C. Gyssens
Keyword(s):  
Escherichia Coli ◽  
Resistant Strain ◽  
Enterococcus Faecium ◽  
Mixed Cultures ◽  
E Coli ◽  
Abdominal Abscesses ◽  
Pure Cultures ◽  
Vancomycin Resistant ◽  
Time Kill

ABSTRACT To determine the efficacy of trovafloxacin as a possible treatment for intra-abdominal abscesses, we have developed an anaerobic time-kill technique using different inocula to study the in vitro killing ofBacteroides fragilis in pure culture or in mixed culture with either Escherichia coli or a vancomycin-resistant strain of Enterococcus faecium (VREF). With inocula of 5 × 105 CFU/ml and trovafloxacin concentrations of ≤2 μg/ml, a maximum observed effect (E max) of ≥6.1 (log10 CFU/ml) was attained with all pure and mixed cultures within 24 h. With inocula of 108CFU/ml, a similar E max and a similar concentration to produce 50% of E max(EC50) for B. fragilis were found in both pure cultures and mixed cultures with E. coli. However, to produce a similar killing of B. fragilis in the mixed cultures with VREF, a 14-fold increase in the concentration of trovafloxacin was required. A vancomycin-susceptible strain of E. faecium and a trovafloxacin-resistant strain of E. coli were also found to confer a similar “protective” effect on B. fragilis against the activity of trovafloxacin. Using inocula of 109 CFU/ml, the activity of trovafloxacin was retained for E. coli and B. fragilis and was negligible against VREF. We conclude that this is a useful technique to study the anaerobic killing of mixed cultures in vitro and may be of value in predicting the killing of mixed infections in vivo. The importance of using mixed cultures and not pure cultures is clearly shown by the difference in the killing of B. fragilis in the mixed cultures tested. Trovafloxacin will probably be ineffective in the treatment of infections involving large numbers of enterococci. However, due to its ability to retain activity against large cultures of B. fragilis and E. coli, trovafloxacin could be beneficial in the treatment of intra-abdominal abscesses.

In Vitro Inhibition of the Growth of Salmonella typhimurium and Escherichia coli 0157:H7 by Bacteria Isolated from the Cecal Contents of Adult Chickens

1991 ◽  
Vol 54 (7) ◽  
pp. 496-501 ◽  
Author(s):  
ARTHUR HINTON ◽  
GEORGE E. SPATES ◽  
DONALD E. CORRIER ◽  
MICHAEL E. HUME ◽  
JOHN R. DELOACH ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Salmonella Typhimurium ◽  
Mixed Cultures ◽  
Enterococcus Durans ◽  
E Coli ◽  
Pure Cultures ◽  
In Vitro Inhibition ◽  
Lactic Acids

A Veillonella species and Enterococcus durans were isolated from the cecal contents of adult broilers. Mixed cultures of Veillonella and E. durans inhibited the growth of Salmonella typhimurium and Escherichia coli 0157:H7 on media containing 2.5% lactose (w/v). The growth of S. typhimurium or E. coli 0157:H7 was not inhibited by mixed cultures containing Veillonella and E. durans on media containing only 0.25% lactose or by pure cultures of Veillonella or E. durans on media containing either 0.25% or 2.5% lactose. The mixed cultures of Veillonella and E. durans produced significantly (P<0.05) more acetic, propionic, and lactic acids in media containing 2.5% lactose than in media containing 0.25% lactose. The inhibition of the enteropathogens was related to the production of lactic acid from lactose by the E. durans and the production of acetic and propionic acids from lactic acid by the Veillonella.

Increased in vitro sensitivity of Candida albicans to amphotericin B when grown in mixed culture with Escherichia coli

1978 ◽  
Vol 24 (12) ◽  
pp. 1482-1489 ◽  
Author(s):  
L. G. Mathieu ◽  
D. Dube ◽  
M. Lebrun
Keyword(s):  
Escherichia Coli ◽  
Candida Albicans ◽  
Amphotericin B ◽  
Mixed Culture ◽  
Mixed Cultures ◽  
Polyene Antibiotics ◽  
E Coli ◽  
Pure Cultures

The growth of Candida albicans was inhibited by some Escherichia coli strains both in conventional batch cultures and also in a chemostat under conditions of constant addition of fresh medium. Concentrations of 0.2 μg amphotericin B per millilitre and of 2 μg nystatin per millilitre, which caused a slight inhibition of C. albicans in pure culture, exerted a strong fungicidal effect when the yeast was placed in mixed cultures with certain strains of E. coli. Candida albicans cells, inhibited by either E. coli or in mixed culture with polyene antibiotics, appeared larger and less uniformly stained by acridine orange than control cells from pure cultures. Addition of chloramphenicol to the mixed cultures, in quantities sufficient to kill the E. coli cells, abolished the increased sensitivity of C. albicans to amphotericin B or nystatin. In preliminary in vivo tests, E. coli did not sensitize C. albicans to the polyene antibiotics.

scholarly journals In vitro activity of piperacillin/tazobactam and ertapenem against Bacteroides fragilis and Escherichia coli in pure and mixed cultures

2007 ◽  
Vol 56 (6) ◽  
pp. 798-802 ◽  
Author(s):  
Kênia Valéria dos Santos ◽  
Cláudio Galuppo Diniz ◽  
Simone Cristina Coutinho ◽  
Ana Carolina Morais Apolônio ◽  
Luciana Geralda de Sousa-Gaia ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacteroides Fragilis ◽  
Mixed Cultures ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
In Vitro Activity ◽  
E Coli ◽  
Agar Dilution ◽  
Time Kill

Ertapenem and piperacillin/tazobactam are β-lactam antibiotics with a broad spectrum of activity used for the treatment of mixed infections in which Bacteroides fragilis and Escherichia coli play an important aetiological role. In this study, the activities of piperacillin/tazobactam and ertapenem (MIC and time–kill kinetics) against these bacteria were compared. MICs were determined by the agar dilution method, and the time and slope of time–kill curves were analysed. In the in vitro pharmacodynamic assays, pure and mixed cultures of E. coli and B. fragilis were exposed to peak concentrations of ertapenem (8.0 μg ml−1) and piperacillin/tazobactam (64.0/8.0 μg ml−1) for 48 h. Treatment with ertapenem reduced the viability of E. coli and/or B. fragilis by 3 logs in all experiments, whereas piperacillin/tazobactam only affected the viability of B. fragilis. Both drugs exhibited their fastest rates of killing when bacteria were grown in mixed cultures. According to the results, ertapenem exhibited activity similar to that of piperacillin/tazobactam against B. fragilis alone or in mixed culture. However, ertapenem exhibited a markedly higher activity against E. coli alone or in combination with B. fragilis relative to piperacillin/tazobactam.

scholarly journals Caracterización molecular de bacterias con potencial probiótico aisladas de heces de neonatos humanos

2019 ◽  
Vol 26 (1) ◽  
pp. 119-130
Author(s):  
Ricardo Santos ◽  
Elizabeth Paitán ◽  
Alejandrina Sotelo ◽  
Doris Zúñiga ◽  
Carlos Vílchez
Keyword(s):  
Escherichia Coli ◽  
16S Rrna ◽  
Enterococcus Faecium ◽  
Salmonella Enterica ◽  
E Coli

El objetivo de este estudio es caracterizar molecularmente bacterias con potencial probiótico aisladas de heces de neonatos humanos. Se evaluó 60 muestras de heces de neonatos (0-3 días) se enriquecieron en caldo Man Rogosa y Sharp (MRS) a 37°C/24h. Se seleccionó y se sometió a pruebas in vitro con sales biliares, resistencia a pH bajo y actividad antimicrobiana frente a Escherichia coli ATCC25922, E. coli ATCC35218, Salmonella enterica y Listeria inocua mediante el ensayo difusión en agar. La identificación molecular se realizó con amplificaciones PCR-BOX y el secuenciamiento del gen 16S rRNA. Se aislaron un total de 48 cepas y todas presentaron resistencia a pH 3 y 0.3% sales biliares; 3 cepas mostraron actividad antimicrobiana frente a E. coli ATCC25922, 1 cepa frente a E. coli ATCC35218, 5 cepas frente a L. inocua y todas frente a S. entérica. De las 48 cepas se obtuvieron dos perfiles BOX-PCR pertenecientes a los géneros de Lactobacillus y Enterococcus. Nueve cepas (C52, C61, C71, C112, C16 2, C192, C20, C35, y C42) presentaron un 100% de similaridad a L. plantarum ATCC 14917T [ACGZ01000098] y dos cepas (C15 y C40) un 99.93% y 99.80% de similaridad, respectivamente a Enterococcus faecium CGMCC 1.2136T [AJKH01000109]; estas cepas mostraron actividad en leche con diferencias significativas (p valor < 0.05) en la cinética de pH 3. En conclusión se encontró bacterias con potencial probiótico.

scholarly journals Dimercaptosuccinic acid in combination with carbapenems against isogenic strains of Escherichia coli producing or not producing a metallo-β-lactamase in vitro and in murine peritonitis

2020 ◽  
Vol 75 (12) ◽  
pp. 3593-3600 ◽  
Author(s):  
G Cheminet ◽  
V de Lastours ◽  
L Poirel ◽  
F Chau ◽  
K Peoc’h ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Peritoneal Fluid ◽  
Dimercaptosuccinic Acid ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Bacterial Counts ◽  
E Coli ◽  
Time Kill ◽  
Isogenic Strains

Abstract Background Carbapenemase-producing Enterobacterales represent a major therapeutic challenge. MBLs, requiring zinc at their catalytic site, could be inhibited by meso-dimercaptosuccinic acid (DMSA), a heavy metal chelator already widely used for treating lead intoxication. Objectives To evaluate the activity of carbapenems alone or combined with DMSA against MBL-producing Escherichia coli in a severe murine peritonitis model. Methods Isogenic strains of wild-type E. coli CFT073 producing the MBLs NDM-1, VIM-2 and IMP-1, and the control serine carbapenemases OXA-48 and KPC-3 were constructed. MIC determinations and time–kill assays were performed for imipenem, meropenem and ertapenem alone or in combination with DMSA. Infected mice were treated intraperitoneally for 24 h with imipenem, DMSA or their combination. Bacterial counts in peritoneal fluid and spleen were assessed at 24 h. Results DMSA in combination with each carbapenem caused a significant decrease in the MICs for all MBL-producing strains, in a concentration-dependent manner, but did not provide benefit against non-MBL strains. In mice infected with the NDM-1-producing strain, the combination of imipenem and DMSA significantly reduced bacterial counts in peritoneal fluid (P = 0.0006) and spleen (P &lt; 0.0001), as compared with imipenem alone, with no benefit against the KPC-3-producing and CFT073 strains. DMSA concentrations in plasma of mice were comparable to those obtained in humans with a standard oral dose. Conclusions DMSA restores the activity of carbapenems against MBL-producing strains, and its combination with carbapenems appears to be a promising strategy for the treatment of NDM-producing E. coli infections.

Interactions of Pseudomonas aeruginosa in predominant biofilm or planktonic forms of existence in mixed culture with Escherichia coli in vitro

2013 ◽  
Vol 59 (9) ◽  
pp. 604-610 ◽  
Author(s):  
Marina V. Kuznetsova ◽  
Irina L. Maslennikova ◽  
Tamara I. Karpunina ◽  
Larisa Yu. Nesterova ◽  
Vitaly A. Demakov
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Total Concentration ◽  
Single Species ◽  
Mixed Cultures ◽  
Interspecies Interactions ◽  
E Coli ◽  
Predominant Form ◽  
The One

Pseudomonas aeruginosa and Escherichia coli are known to be involved in mixed communities in diverse niches. In this study we examined the influence of the predominant form of cell existence of and the exometabolite production by P. aeruginosa strains on interspecies interactions, in vitro. Bacterial numbers of P. aeruginosa and E. coli in mixed plankton cultures and biofilms compared with their numbers in single plankton cultures and biofilms changed in a different way, but were in accordance with the form of P. aeruginosa cell existence. The mass of a mixed-species biofilm was greater than the mass of a single-species biofilm. Among the mixed biofilms, the one with the “planktonic” P. aeruginosa strain had the least biomass. The total pyocyanin and pyoverdin levels were found to be lower in all mixed plankton cultures. Despite this, clinical P. aeruginosa strains irrespective of the predominant form of existence (“biofilm” or “planktonic”) had a higher total concentration of exometabolites than did the reference strain in 12–24 h mixed cultures. The metabolism of E. coli, according to its bioluminescence, was reduced in mixed cultures, and the decrease was by 20- to 100-fold greater with the clinical Pseudomonas strains than the reference Pseudomonas strain. Thus, both the predominant form of existence of and the exometabolite production by distinct P. aeruginosa strains should be considered to fully understand the interspecies relationship and bacteria survival in natural communities.

scholarly journals Ampicillin Enhances Daptomycin- and Cationic Host Defense Peptide-Mediated Killing of Ampicillin- and Vancomycin-Resistant Enterococcus faecium

2011 ◽  
Vol 56 (2) ◽  
pp. 838-844 ◽  
Author(s):  
George Sakoulas ◽  
Arnold S. Bayer ◽  
Joseph Pogliano ◽  
Brian T. Tsuji ◽  
Soo-Jin Yang ◽  
...  
Keyword(s):  
Surface Charge ◽  
Host Defense ◽  
Enterococcus Faecium ◽  
Polymyxin B ◽  
Resistant Bacteria ◽  
Cationic Peptides ◽  
Vancomycin Resistant ◽  
Time Kill ◽  
The Impact

ABSTRACTWe studied an ampicillin- and vancomycin-resistantEnterococcus faecium(VRE) isolate from a patient with endocarditis and bacteremia refractory to treatment with daptomycin (6 mg/kg of body weight) plus linezolid. Blood cultures cleared within 24 h of changing therapy to daptomycin (12 mg/kg) plus ampicillin. We examined the effects of ampicillin on daptomycin-induced growth inhibition and killing, surface charge, and susceptibility to several prototypical host defense cationic antimicrobial peptides. MICs and time-kill curves with daptomycin were assessed in the presence and absence of ampicillin. The impact of ampicillin on surface charge was assessed by flow cytometry and a poly-l-lysine binding assay. The effects of ampicillin preexposures upon VRE killing by five distinct cationic peptides of different structure, charge, origin, and mechanism of action were analyzed using the epidermal cathelicidin LL-37, thrombin-induced platelet microbicidal proteins (tPMPs), and a synthetic congener modeled after tPMP microbicidal domains (RP-1), human neutrophil peptide-1 (hNP-1), and polymyxin B (bacteria derived). Fluoroscein-Bodipy-labeled daptomycin was used to evaluate daptomycin binding to VRE membranes in the presence or absence of ampicillin. In media containing ampicillin (25 to 100 mg/liter), daptomycin MICs decreased from 1.0 to 0.38 mg/liter. Based on time-kill analysis and anin vitropharmacodynamic model, ampicillin enhanced daptomycin activity against the study VRE from a bacteriostatic to a bactericidal profile. VRE grown in ampicillin (25 to 150 mg/liter) demonstrated an incremental reduction in its relative net positive surface charge. When grown in the presence (versus absence) of ampicillin (25 and 100 mg/liter), the VRE strain (i) was more susceptible to killing by LL-37, tPMPs, hNP-1, and RP-1 but not to polymyxin B and (ii) exhibited greater binding to Bodipy-labeled daptomycin. We conclude that ampicillin induces reductions in net positive bacterial surface charge of VRE, correlating with enhanced bactericidal effects of cationic calcium-daptomycin and a diverse range of other cationic peptidesin vitro. While the mechanism(s) of such β-lactam-mediated shifts in surface charge remains to be defined, these finding suggest a potential for β-lactam-mediated enhancement of activity of both daptomycin and innate host defense peptides against antibiotic-resistant bacteria.

scholarly journals In vitro activities of an investigational quinolone, glycylcycline, glycopeptide, streptogramin, and oxazolidinone tested alone and in combinations against vancomycin-resistant Enterococcus faecium.

1997 ◽  
Vol 41 (11) ◽  
pp. 2573-2575 ◽  
Author(s):  
R C Mercier ◽  
S R Penzak ◽  
M J Rybak
Keyword(s):  
Growth Inhibition ◽  
Active Treatment ◽  
Enterococcus Faecium ◽  
Vancomycin Resistant Enterococcus ◽  
Bacterial Inoculum ◽  
Vancomycin Resistant ◽  
Kill Curve ◽  
Time Kill

We evaluated the in vitro activities of clinafloxacin, CL331,002, LY333328, quinupristin dalfopristin, and eperezolid (formerly known as U-100,592) against four strains of enterococci. All regimens tested resulted in the growth inhibition of each isolate. Against the three clinafloxacin-susceptible strains, clinafloxacin tested alone was the most active treatment, decreasing the bacterial inoculum by more than 3 log10 CFU/ml after 24 h in time-kill curve studies.

Synergy Testing of Vancomycin-Resistant Enterococcus faecium against Quinupristin-Dalfopristin in Combination with Other Antimicrobial Agents

1999 ◽  
Vol 43 (11) ◽  
pp. 2776-2779 ◽  
Author(s):  
S. O. Matsumura ◽  
L. Louie ◽  
M. Louie ◽  
A. E. Simor
Keyword(s):  
Clinical Evaluation ◽  
Enterococcus Faecium ◽  
Antimicrobial Agents ◽  
Vitro Activity ◽  
Vancomycin Resistant Enterococcus ◽  
In Vitro Activity ◽  
Vancomycin Resistant ◽  
Time Kill ◽  
Synergy Testing

ABSTRACT Using checkerboard and time-kill assays, we evaluated the in vitro activity of quinupristin-dalfopristin (RP 59500) alone and in combination with five other antimicrobial agents against 12 clinical strains of vancomycin-resistant Enterococcus faecium(VREF). In time-kill studies, six VREF strains exhibited synergism with the combination of quinupristin-dalfopristin and doxycycline and three exhibited synergism with quinupristin-dalfopristin plus ampicillin-sulbactam. Combinations of quinupristin-dalfopristin with these and other agents warrant further clinical evaluation for the treatment of serious VREF infections.

scholarly journals In Vitro Activity of Fenticonazole against Candida and Bacterial Vaginitis Isolates Determined by Mono- or Dual-Species Testing Assays

2019 ◽  
Vol 63 (7) ◽  
Author(s):  
Maurizio Sanguinetti ◽  
Emilia Cantón ◽  
Riccardo Torelli ◽  
Fabio Tumietto ◽  
Ana Espinel-Ingroff ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Candida Glabrata ◽  
Candida Parapsilosis ◽  
Bacterial Species ◽  
In Vitro Activity ◽  
Content Type ◽  
E Coli ◽  
Time Kill

ABSTRACT We determined the in vitro activity of fenticonazole against 318 vaginitis isolates of Candida and bacterial species and selected 28 isolates for time-kill studies. At concentrations equal to 4× MIC, fenticonazole reached the 99.9% killing endpoint by ∼10 h for Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli and by ∼17 h for Candida albicans and Candida parapsilosis; and at concentrations equal to 8× MIC, by ∼19 and ∼20 h for Candida glabrata and Candida tropicalis, respectively. At concentrations equal to 2× MIC, fenticonazole required ∼20 h to reach the above endpoint against C. albicans in mixed culture with S. aureus, S. agalactiae, or E. coli versus ∼17 h against C. albicans in pure culture. Supra-MICs are achievable in topically treated patients’ vaginal surfaces.

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