scholarly journals Stability of β-lactam antibiotics in bacterial growth media

2020 ◽  
Author(s):  
Rebecca Brouwers ◽  
Hugh Vass ◽  
Angela Dawson ◽  
Tracey Squires ◽  
Sharareh Tavaddod ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Minimum Inhibitory Concentration ◽  
Growth Medium ◽  
Bacterial Growth ◽  
Half Life ◽  
Inhibitory Concentration ◽  
Luria Bertani ◽  
Growth Media ◽  
Rapid Degradation ◽  
Degradation Rates

AbstractLaboratory assays such as MIC tests assume that antibiotic molecules are stable in the chosen growth medium - but rapid degradation has been observed for antibiotics including β-lactams under some conditions in aqueous solution. Degradation rates in bacterial growth medium are less well known. Here, we develop a ‘delay time bioassay’ that provides a simple way to estimate antibiotic stability in bacterial growth media. We use the bioassay to measure degradation half-lives of the β-lactam antibiotics mecillinam, aztreonam and cefotaxime in widely-used bacterial growth media based on MOPS and Luria-Bertani (LB) broth. We find that mecillinam degradation can occur rapidly, with a half-life as short as 2 hours in MOPS medium at 37°C and pH 7.4, and 4-5 hours in LB, but that adjusting the pH and temperature can increase its stability to a half-life around 6 hours without excessively perturbing growth. Aztreonam and cefotaxime were found to have half-lives longer than 6 hours in MOPS medium at 37°C and pH 7.4, but still shorter than the timescale of a typical minimum inhibitory concentration (MIC) assay. Taken together, our results suggest that care is needed in interpreting MIC tests and other laboratory growth assays for β-lactam antibiotics, since there may be significant degradation of the antibiotic during the assay.

scholarly journals A study of the type of antimicrobial action of novel compounds synthesized from substituted benzaminoindoles

2019 ◽  
pp. 57-64
Author(s):  
IS Stepanenko ◽  
SA Yamashkin ◽  
YuA Kostina ◽  
ED Slastnikov ◽  
AA Batarsheva
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Minimum Inhibitory Concentration ◽  
Optical Density ◽  
Bacterial Growth ◽  
Culture Medium ◽  
Inhibitory Concentration ◽  
Antimicrobial Action ◽  
Bacteriostatic Effect ◽  
Minimum Inhibitory Concentrations

The antimicrobial activity of novel compounds is tested by determining the minimum inhibitory concentration of the agent in question and investigating a few other parameters, including the type of antimicrobial action the drug exhibits. The aim of this study was to determine the type of antimicrobial action of the compounds synthesized from the substituted benzaminoindoles. The strain of Staphylococcus aureus АТСС 6538-Р was briefly exposed to the compounds with laboratory codes 5D, 7D, HD, and S3. Bacterial growth was evaluated macroscopically under transmitted light. Additionally, photoelectric colorimetry was applied to monitor changes in the optical density of the culture medium. The minimum inhibitory concentrations of the studied compounds delayed bacterial growth for 2–3 days and had a bacteriostatic effect on S. aureus.

scholarly journals Action of methicillin on the "in vitro" growth of bacteria Staphyloccocus aureus methicillin-resistance previously treated with homeopathic dilutions

2021 ◽  
Vol 14 (2) ◽  
pp. 57-58
Author(s):  
Tania Aguiar Passeti ◽  
Leandro Ribeiro Bissoli ◽  
Registila Libania Beltrame E Fernando Fonsceca
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Bacterial Growth ◽  
Inhibitory Concentration ◽  
Methicillin Resistance ◽  
Bacterial Suspension ◽  
Bacterial Strains ◽  
Bacterial Cultures ◽  
Staphyloccocus Aureus ◽  
New Strategies

Background: Methicillin-resistant Staphylococcus aureus (MRSA) causes nosocomial infections, and it has been considered as a worldwide epidemic. The medical system seeks new strategies to fight against MRSA that do not generate resistant strains to antibiotics. Homeopathy has been explored as one of these new strategies, which may play a pivotal role. In this context, we conducted studies on the action of homeopathy on growth of MRSA bacteria in vitro. The results showed a decrease in growth of bacterial strains with homeopathic dilutions of Belladonna and the S. aureus nosode. Now we have proposed to evaluate the minimum inhibitory concentration (MIC) of the antibiotic methicillin or oxacillin on S. aureus MRSA, previously incubated with the homeopathic dilutions of Belladonna or S. aureus nosode. Methods: The Clinical and Laboratory Standards Institute (CLSI 2014) standards were followed according to the determination of the minimum inhibitory concentration (MIC). In 5 mL of cation adjusted Mueller Hinton (CAMH) broth, it was added 420 µl of 30% alcohol or Belladonna and S. aureus’ nosode in the dilutions 6cH, 12cH and 30cH. Then a 20µl of bacterial suspension of MRSA was added to 0.5 McFarland range and diluted to 1/10. The tubes were incubated in an oven at 37⁰C for three hours. The plates were previously prepared with 50µl per well of serial dilutions of the antibiotic oxacillin in concentrations of 128 µg/mL to 0.5 µg/mL in CAMH broth. Then it was added 50 µl per well of bacterial cultures. The plate was incubated in an oven at 37⁰C for 24 hours and the bacterial growth measured in a spectrophotometer 600nm. The point of the MIC of oxacillin for S. aureus is 4 µg/mL, according to CLSI 2014 criteria. Results: We did not observe the total inhibition of bacterial growth when incubated with the homeopathic medicine and oxacillin. In evaluation of the spectrophotometer culture, we observed significant changes in the growth, compared to the control (30% alcohol). Cultures treated with Belladonna 6cH and the antibiotic in the dilution 4 µg/mL showed a decrease of 40% of the growth, while in the 30cH the drop was of 75%. Cultures treated with the S. aureus nosode 30cH and the antibiotic at 4 µg/mL dilution, showed a decrease of 60% in bacterial growth in vitro. Conclusion: The results suggest that bacterial cultures the S. aureus (MRSA) incubated with the homeopathic medicines would be more susceptible to oxacillin’s antimicrobial action.

scholarly journals Determination of Minimum Inhibitory Concentration (MIC) and percentage Bacterial Growth Inhibition of essential oils against Gram Positive Bacterial pathogens

2019 ◽  
Vol 9 (3) ◽  
pp. 33-35
Author(s):  
S. Nagalakshmi ◽  
P. Saranraj ◽  
P. Sivasakthivelan
Keyword(s):  
Staphylococcus Aureus ◽  
Bacillus Subtilis ◽  
Minimum Inhibitory Concentration ◽  
Growth Inhibition ◽  
Essential Oils ◽  
Bacterial Growth ◽  
Inhibitory Concentration ◽  
Gram Positive ◽  
Bacterial Growth Inhibition

Essential oils and volatile constituents extracted from Aromatic plants are frequently used in folk medicine for prevention and treatment of different human diseases. The urge to develop alternative treatment strategies follows three different directions. In the present study, an attempt has been planned to determine the Minimum Inhibitory Concentration (MIC) and Percentage Growth Inhibition of Essential oils against two Gram positive bacterial pathogens, Staphylococcus aureus and Bacillus subtilis. The Essential oils selected for the present study was collected from Sidha Medicine Shop, Tirupattur, Vellore district, Tamil Nadu, India. The Broth dilution method was used for the determination of Minimum Inhibitory Concentration (MIC) of Essential oils. The Minimum Inhibitory Concentration (MIC) studies were conducted by using various concentrations of Essential oils viz., 25 µl/ml, 50 µl/ml, 75 µl/ml and 100 µ/ml. The Essential oils exhibits inhibitory activity against Gram positive bacteria in all the concentrations. Among the seven Essential oils tested, Mahualongif oil has showed maximum percentage bacterial growth inhibition when compared to other Essential oils. The inhibitory activity of Mahualongif oil was observed more in Staphylococcus aureus when compared to Bacillus subtilis. For Staphylococcus aureus, lowest inhibitory percentage was noticed in Pungam oil and for Bacillus subtilis lowest inhibitory percentage was noticed in Coconut oil. Keywords: Essential oils, Minimum inhibitory concentration (MIC), Percentage bacterial growth inhibition, Bacillus subtilis and Staphylococcus aureus.

scholarly journals Use of the Microbial Growth Curve in Postantibiotic Effect Studies of Legionella pneumophila

2003 ◽  
Vol 47 (3) ◽  
pp. 1081-1087 ◽  
Author(s):  
Raymond P. Smith ◽  
Aldona L. Baltch ◽  
Phyllis B. Michelsen ◽  
William J. Ritz ◽  
Richard Alteri
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Bacterial Growth ◽  
Legionella Pneumophila ◽  
Microbial Growth ◽  
Inhibitory Concentration ◽  
Growth Curves ◽  
Laboratory Medicine ◽  
Postantibiotic Effect ◽  
Antibiotic Concentration

ABSTRACT Using the standard Craig and Gudmundsson method (W. A. Craig and S. Gudmundsson, p. 296-329, in V. Lorian, ed., Antibiotics in Laboratory Medicine, 1996) as a guideline for determination of postantibiotic effects (PAE), we studied a large series of growth curves for two strains of Legionella pneumophila. We found that the intensity of the PAE was best determined by using a statistically fitted line over hours 3 to 9 following antibiotic removal. We further determined the PAE duration by using a series of observations of the assay interval from hours 3 to 24. We determined that inoculum reduction was not necessarily the only predictor of the PAE but that the PAE was subject to the type and dose of the drug used in the study. In addition, there was a variation between strains. Only levofloxacin at five and ten times the minimum inhibitory concentration (MIC) resulted in a PAE duration of 4 to 10 h for both strains of L. pneumophila tested. Ciprofloxacin at five and ten times the MIC and azithromycin at ten times the MIC caused a PAE for one strain only. No PAE could be demonstrated for either strain with erythromycin or doxycycline. Using the presently described method of measuring PAE for L. pneumophila, we were able to detect differences in PAE which were dependent upon the L. pneumophila strain, the antibiotic tested, and the antibiotic concentration. We suggest the use of mathematically fitted curves for comparison of bacterial growth in order to measure PAE for L. pneumophila.

scholarly journals Determination of Tedizolid in Bacterial Growth Medium Mueller-Hinton Broth by High-Performance Liquid Chromatography and Its Application to an In Vitro Study in the Hollow-Fiber Infection Model

Separations ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 141
Author(s):  
Khalid Iqbal ◽  
Aliki Milioudi ◽  
Elena Haro Martínez ◽  
Sebastian Georg Wicha
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Growth Medium ◽  
Bacterial Growth ◽  
High Performance ◽  
Infection Model ◽  
Growth Media ◽  
Mueller Hinton ◽  
Mueller Hinton Broth

Pharmacokinetic/pharmacodynamic (PKPD) studies of anti-infectives are frequently performed in in vitro infection models where accurate quantification of antibiotic concentrations in bacterial growth media is crucial to establish PK/PD relationships. Here, a sensitive and rapid high-performance liquid chromatography (HPLC) method was developed to quantify tedizolid (TDZ) in the bacterial growth medium Mueller-Hinton broth (MHB). Matrix components were separated by direct protein precipitation with methanol (1:1). The chromatographic separation was carried out in a Dionex Ultimate 3000 HPLC system using an Accucore® C-18 RPMS HPLC column (2.6 µm, 100 × 2.1 mm) using isocratic elution with 25% acetonitrile and 75% of 0.1% formic acid. The lower limit of quantification was 0.03 mg/L when measured at 300 nm. Following relevant European Medicine Agency guidelines, the method was successfully validated for linearity, selectivity, recovery, inter- and intra-day precision, and accuracy and stability. When applied to in vitro PKPD studies, the method successfully quantified a range of TDZ concentration (Cmin, 0.09-Cmax, 0.65 mg/L) in MHB. The analyzed concentrations were in line with the planned PK profiles. The application of the developed method to quantify TDZ in MHB in in vitro PKPD studies is warranted.

scholarly journals Potensi Ekstrak Daun Binahong (Anredera cordifolia) Sebagai Penghambat Bakteri Vibrio harveyi

2016 ◽  
Vol 2 (2) ◽  
pp. 49 ◽  
Author(s):  
Gde Raka Angga Kartika ◽  
Sri Andayani ◽  
Soelistyowati Soelistyowati
Keyword(s):  
Minimum Inhibitory Concentration ◽  
Bacterial Growth ◽  
Leaf Extract ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Vibrio Harveyi ◽  
Antioxidant Content ◽  
Paper Disc ◽  
Growth Of Bacteria

Binahong (Anredera cordifolia) is a plant that can treat various kinds of diseases, because this plant has a high antioxidant content and as an antibacterial and antiviral. Vibriosis disease caused by the bacterium Vibrio harveyi is a serious problem in marine and brackish culture, this disease can cause death for shrimp and fish that farmed in marine or brackish. This study aims to determine the potential of using leaf extract Binahong with different concentrations as Vibrio harveyi inhibiting bacterial growth in vitro. The method used is to test the Minimum inhibitory concentration (MIC) to determine minimum levels inhibit the growth of Vibrio harveyi and Minimum Bactericidal Concentration (MBC) using paper disc. The results showed the use of leaf extract Binahong (Anredera cordifolia) with different concentrations significant effect on the growth of Vibrio harveyi in vitro. Binahong leaf extract (Anredera cordifolia) with a concentration of 3%, 5%, 7%, 9%, 11% and 13% is only bacteriostatic which inhibits the growth of bacteria Vibrio harveyi with the best concentration obtained is equal to 13%.

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