scholarly journals Predicting Oral Beta-lactam susceptibilities against Streptococcus pneumoniae

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mark E. Murphy ◽  
Eleanor Powell ◽  
Joshua Courter ◽  
Joel E. Mortensen
Keyword(s):  
Streptococcus Pneumoniae ◽  
Inhibitory Concentration ◽  
Beta Lactam ◽  
Oral Cephalosporin ◽  
Ionization Time ◽  
Flight Mass Spectrometry ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Risk Of Treatment ◽  
Susceptibility Patterns

Abstract Background Oral beta-lactam antimicrobials are not routinely tested against Streptococcus pneumoniae due to presumed susceptibility based upon penicillin minimum inhibitory concentration (MIC) testing. Currently, Clinical and Laboratory Standards Institute provides comments to use penicillin MIC ≤0.06 to predict oral cephalosporin susceptibility. However, no guidance is provided when cefotaxime MIC is known, leading to uncertainty with interpretation. The purpose of this study was to evaluate cefotaxime and penicillin MICs and their respective correlation to oral beta-lactam categorical susceptibility patterns. Methods 249 S. pneumoniae isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF) and then tested by broth microdilution method to penicillin, cefotaxime, amoxicillin, cefdinir, cefpodoxime, and cefuroxime. Results Using Clinical and Laboratory Standards Institute (CLSI) non-meningitis breakpoints for cefotaxime, 240/249 isolates were classified as susceptible. Of the cefotaxime susceptible isolates, 23% of the isolates are misrepresented as cefdinir susceptible. Amoxicillin correlated well with penicillin MIC breakpoints with only 1 discordant isolate out of 249. Conclusion The correlation between amoxicillin and penicillin creates a very reliable predictor to determine categorical susceptibility. However oral cephalosporins were not well predicted by either penicillin or cefotaxime leading to the possible risk of treatment failures. Caution should be used when transitioning to oral cephalosporins in cefotaxime susceptible isolates, especially with higher cefotaxime MICs.

scholarly journals In Vitro Susceptibility of Fusarium to Isavuconazole

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
A. Broutin ◽  
J. Bigot ◽  
Y. Senghor ◽  
A. Moreno-Sabater ◽  
J. Guitard ◽  
...  
Keyword(s):  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
In Vitro Susceptibility ◽  
Ionization Time ◽  
Valuable Alternative ◽  
Flight Mass Spectrometry ◽  
Microdilution Method ◽  
Species Complexes ◽  
Broth Microdilution Method

ABSTRACT To evaluate the in vitro susceptibility of Fusarium to isavuconazole, 75 clinical isolates were identified using matrix-assisted laser desorption ionization–time of flight mass spectrometry and then tested with a broth microdilution method (EUCAST) and the gradient concentration strip (GCS) technique. The activity of isavuconazole overall was shown to be limited, with an MIC50 of >16 μg/ml, without significant differences between the species complexes. The categorical agreement between GCS and EUCAST was 97.4% to 100%, making the GCS as a valuable alternative.

Comparison of antimicrobial resistance patterns in Streptococcus pneumoniae from respiratory and blood cultures in Canadian hospitals from 2007–16

2019 ◽  
Vol 74 (Supplement_4) ◽  
pp. iv39-iv47 ◽  
Author(s):  
Alyssa R Golden ◽  
Melanie R Baxter ◽  
Ross J Davidson ◽  
Irene Martin ◽  
Walter Demczuk ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Susceptibility ◽  
Invasive Disease ◽  
Non Invasive ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Resistance Patterns ◽  
Specific Factors ◽  
Susceptibility Patterns ◽  
Respiratory Specimens

Abstract Objectives To compare the epidemiology and antimicrobial susceptibility patterns of Streptococcus pneumoniae collected from respiratory and blood culture samples in Canada between 2007 and 2016. Methods S. pneumoniae strains were obtained from Canadian hospitals as part of the ongoing national surveillance study, CANWARD. Isolates were serotyped using the Quellung method. Antimicrobial susceptibility testing was performed using the CLSI broth microdilution method. MDR and XDR were defined as resistance to three or more and five or more classes of antimicrobials, respectively. Results Of the 2581 S. pneumoniae isolates collected, 1685 (65.3%) and 896 (34.7%) were obtained from respiratory and blood samples, respectively. Respiratory isolates demonstrated lower rates of antimicrobial susceptibility than blood isolates to penicillin, ceftriaxone, clarithromycin, clindamycin, doxycycline and trimethoprim/sulfamethoxazole (P ≤ 0.03). From 2007 to 2016, invasive isolates demonstrated trends towards increasing penicillin susceptibility and decreasing clarithromycin susceptibility. MDR was significantly higher in respiratory S. pneumoniae compared with blood (9.1% versus 4.5%, P < 0.0001). Serotypes 11A, 16F, 19F, 23A/B/F, 34, 35B and non-typeable strains were more commonly isolated from respiratory specimens, while 4, 5, 7F, 8, 12F, 14 and 19A were more commonly invasive serotypes. Numerous serotypes, including 3 and 22F, were isolated frequently from both specimen sources. Conclusions S. pneumoniae from respiratory samples demonstrated lower antimicrobial susceptibilities and higher MDR in a greater diversity of serotypes than isolates obtained from blood. Many serotypes were associated with one specific specimen source, while others were associated with both; genetic characterization is necessary to elucidate the specific factors influencing the ability of these serotypes to commonly cause both invasive and non-invasive disease.

scholarly journals In VitroAntistaphylococcal Effects ofEmbelia schimperiExtracts and Their Component Embelin with Oxacillin and Tetracycline

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Johana Rondevaldova ◽  
Olga Leuner ◽  
Alemtshay Teka ◽  
Ermias Lulekal ◽  
Jaroslav Havlik ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Medicinal Plants ◽  
Bacterial Infections ◽  
Inhibitory Concentration ◽  
Developed Countries ◽  
Positive Interactions ◽  
Fractional Inhibitory Concentration ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method

Bacterial infections are in less-developed countries traditionally treated by remedies prepared from medicinal plants.Embelia schimperi(Vatke) is a plant used as a taenicide or disinfectant in Ethiopia, very often taken mixed with another plant species. In the present study, we examined two extracts prepared from seeds and twigs with leaves ofE. schimperiand its main present secondary metabolite embelin for their antibacterial combinatory effect with oxacillin and tetracycline against sensitive and resistantStaphylococcus aureusstrains. Minimum inhibitory concentrations were determined through the broth microdilution method, whereas the combinatory effect was evaluated through fractional inhibitory concentration sum (ΣFIC) indices. Results show many positive interactions and synergy occurring in embelin and oxacillin combinations against 4 out of 9 strains (ΣFIC 0.203–0.477) and for embelin and tetracycline combination against 3 out of 9 strains (ΣFIC 0.400–0.496). Moreover, the resistance to oxacillin has been overcome in 2 strains and to tetracycline in 3 strains. According to our knowledge, this is the first study showing antimicrobial combinatory effect ofE. schimperias well as of embelin. These findings can be used for the further research targeted on the development of new antistaphylococcal agents.

scholarly journals Variation in erythromycin and clindamycin susceptibilities of Streptococcus pneumoniae by four test methods.

1997 ◽  
Vol 41 (1) ◽  
pp. 129-134 ◽  
Author(s):  
E L Fasola ◽  
S Bajaksouzian ◽  
P C Appelbaum ◽  
M R Jacobs
Keyword(s):  
Streptococcus Pneumoniae ◽  
Susceptibility Testing ◽  
Ambient Air ◽  
Test Methods ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution ◽  
Resistant Strains

Susceptibilities of 124 strains of Streptococcus pneumoniae to erythromycin and clindamycin were determined by the National Committee for the Clinical Laboratory Standards (NCCLS) broth microdilution method, with incubation for 20 to 24 h in ambient air and with modifications of this method by incubation for up to 48 h in air and CO2. Strains were also tested by agar dilution, E-test, and disk diffusion; good correlation was obtained with these methods, with clear separation into bimodal populations of susceptible and resistant stains. The broth microdilution method, however, using incubation in air for 24 h (NCCLS method), misclassified 4 of 92 erythromycin-resistant strains (1 as susceptible and 3 as intermediate) and 25 of 58 clindamycin-resistant strains (all as susceptible). With the exception of one strain with clindamycin, susceptible and resistant strains were correctly classified by the microdilution method with incubation in CO2 for 24 h or in ambient air for 48 h. Disk diffusion, agar dilution, and E-test methods with incubation in 5% CO2 are therefore reliable methods for susceptibility testing of pneumococci against these agents. However, the NCCLS microdilution method, which specifies incubation for 20 to 24 h in ambient air, produced significant very major errors (43%) clindamycin. Modification of the microdilution method by incubation in 5% CO2 or by extension of incubation time in ambient air to 48 h corrected these errors. Disk diffusion, however, was shown to be a simple, convenient, and reliable method for susceptibility testing of pneumococci to erythromycin and clindamycin and is suggested as the method of choice for these agents.

scholarly journals Antibacterial Activity of 2-(3’,5'-Dibromo-2'-methoxyphenoxy)-3,5-dibromophenol Isolated from Phyllospongia papyracea

2017 ◽  
Vol 12 (4) ◽  
pp. 1934578X1701200 ◽  
Author(s):  
Shi Sun ◽  
Corene Canning ◽  
Kuiwu Wang ◽  
Wenjun Zhu ◽  
Fei Yang ◽  
...  
Keyword(s):  
Antibacterial Agents ◽  
Inhibitory Concentration ◽  
Methanol Extract ◽  
Minimal Bactericidal Concentration ◽  
Antimicrobial Compound ◽  
Highly Active ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Bioassay Guided Fractionation ◽  
And Staphylococcus Aureus

A principal active antimicrobial compound, 2-(3’,5'-dibromo-2'-methoxyphenoxy)-3,5-dibromophenol, was isolated from the methanol extract of Phyllospongia papyracea via bioassay-guided fractionation and isolation. The crude extract and the purified compound were assayed to determine the minimal inhibitory concentration and minimal bactericidal concentration (MBC) using the broth microdilution method. The purified compound was found to be highly active against Bacillus subtilis and Staphylococcus aureus at MIC=1 μg/mL, Campylobacter jejuni at MIC=2 μg/mL, Pseudomonas aeruginosa at MIC=4 μg/mL, and Streptococcus pneumoniae and Listeria monocytogenes at MIC = 8 μg/mL. The activity of this compound was found to be comparable with antibiotics commonly used to control these species of bacteria. The results establish 2-(3’,5'-dibromo-2'-methoxyphenoxy)-3,5-dibromophenol as a potential lead molecule for the development of antibacterial agents.

scholarly journals Curcumin, a Natural Antimicrobial Agent with Strain-Specific Activity

2020 ◽  
Vol 13 (7) ◽  
pp. 153
Author(s):  
Artur Adamczak ◽  
Marcin Ożarowski ◽  
Tomasz M. Karpiński
Keyword(s):  
Inhibitory Concentration ◽  
Specific Activity ◽  
Curcuma Longa ◽  
Antimicrobial Properties ◽  
Antiviral Agent ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Bioactive Substance

Curcumin, a principal bioactive substance of turmeric (Curcuma longa L.), is reported as a strong antioxidant, anti-inflammatory, antibacterial, antifungal, and antiviral agent. However, its antimicrobial properties require further detailed investigations into clinical and multidrug-resistant (MDR) isolates. In this work, we tested curcumin’s efficacy against over 100 strains of pathogens belonging to 19 species. This activity was determined by the broth microdilution method and by calculating the minimum inhibitory concentration (MIC). Our findings confirmed a much greater sensitivity of Gram-positive than Gram-negative bacteria. This study exhibited a significantly larger variation in the curcumin activity than previous works and suggested that numerous clinical strains of widespread pathogens have a poor sensitivity to curcumin. Similarly, the MICs of the MDR types of Staphylococcus aureus, S. haemolyticus, Escherichia coli, and Proteus mirabilis were high (≥2000 µg/mL). However, curcumin was effective against some species and strains: Streptococcus pyogenes (median MIC = 31.25 µg/mL), methicillin-sensitive S. aureus (250 µg/mL), Acinetobacter lwoffii (250 µg/mL), and individual strains of Enterococcus faecalis and Pseudomonas aeruginosa (62.5 µg/mL). The sensitivity of species was not associated with its affiliation to the genus, and it could differ a lot (e.g., S. pyogenes, S. agalactiae and A. lwoffii, A. baumannii). Hence, curcumin can be considered as a promising antibacterial agent, but with a very selective activity.

scholarly journals In Vitro Interaction of Caspofungin Acetate with Voriconazole against Clinical Isolates of Aspergillus spp

2002 ◽  
Vol 46 (9) ◽  
pp. 3039-3041 ◽  
Author(s):  
Sofia Perea ◽  
Gloria Gonzalez ◽  
Annette W. Fothergill ◽  
William R. Kirkpatrick ◽  
Michael G. Rinaldi ◽  
...  
Keyword(s):  
Inhibitory Concentration ◽  
Fractional Inhibitory Concentration ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
In Vitro Interaction ◽  
Vitro Data ◽  
In Vitro Data

ABSTRACT The interaction between caspofungin acetate and voriconazole was studied in vitro by using 48 clinical Aspergillus spp. isolates obtained from patients with invasive aspergillosis. MICs were determined by the NCCLS broth microdilution method. Synergy, defined as a fractional inhibitory concentration (FIC) index of <1, was detected in 87.5% of the interactions; an additive effect, defined as an FIC index of 1.0, was observed in 4.2% of the interactions; and a subadditive effect, defined as an FIC index of 1.0 to 2.0, was found in 8.3% of the interactions. No antagonism was observed. Animal models are required to validate the in vivo significance of these in vitro data presented for the combination of caspofungin and voriconazole.

scholarly journals Validation of a method of broth microdilution for the determination of antibacterial activity of essential oils

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Vanegas David ◽  
Abril-Novillo Andrea ◽  
Khachatryan Aleksandr ◽  
Jerves-Andrade Lourdes ◽  
Peñaherrera Eugenia ◽  
...  
Keyword(s):  
Essential Oils ◽  
Sensitivity And Specificity ◽  
Inhibitory Concentration ◽  
Tween 80 ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution ◽  
Continuous Contact ◽  
Microdilution Method ◽  
Broth Microdilution Method

Abstract Objective The aim of the present study was to adapt and optimize a broth microdilution method and compare it to the agar dilution method for the evaluation of activity of essential oils from medicinal plants against Gram-negative bacteria. Based on bibliographic research, active and not active oils were selected. The sensitivity and specificity were established as parameters for validation. The comparison between both methods was made using contingency analysis tables, based on the observed frequencies. For both methods, the minimum inhibitory concentration was determined against Escherichiacoli strains, in an essential oil concentration range between 0.03 and 0.48% (v/v). Results A stable emulsion formation was achieved with the addition of Tween 80 and constant agitation, guaranteeing the continuous contact of oil with bacteria (critical step in the microdilution method). The statistical analysis of results obtained with both methods presented a good sensitivity and specificity (100% in both cases), which let us correctly discriminate between active and non-active oils. The values obtained for the minimal inhibitory concentration were independent of the technique used. Finally, the obtained results show that the validated microtechnique allows important diminishment of time and resources for investigations dealing with essential oils or lipophilic extracts evaluation.

scholarly journals Synergistic Antibiofilm Efficacy of Thymol and Piperine in Combination with Three Aminoglycoside Antibiotics against Klebsiella pneumoniae Biofilms

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Borel Bisso Ndezo ◽  
Christian Ramsès Tokam Kuaté ◽  
Jean Paul Dzoyem
Keyword(s):  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Inhibitory Concentration ◽  
Alternative Therapy ◽  
Aminoglycoside Antibiotics ◽  
Antibiofilm Activity ◽  
Promising Alternative ◽  
Microdilution Method ◽  
Fold Reduction ◽  
Broth Microdilution Method

Background. Thymol and piperine are two naturally occurring bioactive compounds with several pharmacological activities. In this study, their antibiofilm potential either alone or in combination with three aminoglycoside antibiotics was evaluated against a biofilm of Klebsiella pneumoniae. Methods. Determination of antimicrobial susceptibility was performed using the broth microdilution method. Biofilm formation was evaluated by the microtiter plate method. Antibiofilm activity was determined using 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium-bromide (MTT) assay. The combination studies were performed by the checkerboard microdilution method. Results. The minimum biofilm inhibitory concentration (MBIC) of streptomycin was reduced by 16- to 64-fold when used in combination with thymol, while the MBIC of kanamycin was reduced by 4-fold when combined with piperine. The minimum biofilm eradication concentration (MBEC) values of streptomycin, amikacin, and kanamycin were, respectively, 16- to 128-fold, 4- to 128-fold, and 8- to 256-fold higher than the planktonic minimum inhibitory concentration (MIC). Thymol combined with streptomycin or kanamycin showed synergic effects against the preformed biofilm with 16- to 64-fold reduction in the minimum biofilm eradication concentration values of each antibiotic in combination. Piperine acted also synergically with kanamycin with an 8- to 16-fold reduction in the minimum biofilm eradication concentration values of kanamycin in combination. Conclusion. The association of thymol with antibiotics showed a strong synergistic effect both in the inhibition of biofilm formation and the destruction of the preformed biofilm of K. pneumoniae. This study suggests that a combination of thymol with streptomycin, amikacin, or kanamycin could be a promising alternative therapy to overcome the problem of K. pneumoniae biofilm-associated infections.

scholarly journals Investigation of in vitro activity of colistin and tygecyclin against Stenotrophomonas maltophilia isolates

2021 ◽  
Vol 38 (4) ◽  
pp. 529-532
Author(s):  
Yeliz TANRIVERDİ ÇAYCI ◽  
İlknur BIYIK ◽  
Gonca YILMAZ ◽  
Kemal BİLGİN ◽  
Asuman BİRİNCİ
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Inhibitory Concentration ◽  
Treatment Options ◽  
Opportunistic Pathogen ◽  
Diffusion Method ◽  
Colistin Resistance ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Usa

Stenotrophomonas maltophilia has emerged as an important opportunistic pathogen, causing infections whose management is often problematic due to its inherent resistance to many antibiotics. In this study, we aimed to investigate the antimicrobial susceptibility of colistin and tygecyclin as an alternative treatment options for S. maltophilia infections. A total of 122 S. maltophilia isolates were tested. Minimum inhibitory concentration (MIC) values of colistin and tygecycline were determined by broth microdilution method. Susceptibility of TMP/SMX and levofloxacin (LVX) were determined by disc diffusion method and MIC value of ceftazidime (CAZ) was determined by using E-test. Out of 122 S. maltophilia isolates, 5 (4%) of them were resistant to TMP-SXM. MIC range was 0.125- >512 μg/ml and MIC50 64 μg/ml, MIC90 512 μg/ml for colistin. MIC range for tygecyclin was detected as 0.5- >8, MIC50 2 μg/ml and MIC90 8 μg/ml. Tygecyclin resistance was detected as 66.4% according to the EUCAST guideline and 13.1% according to the USA-FDA breakpoints. And colistin resistance was determined as 86.9% according to both guidelines.

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