scholarly journals Disk with High Oxacillin Content Discriminates between Methicillin-Resistant and Borderline Methicillin-SusceptibleStaphylococcus aureus Strains in Disk Diffusion Assays Using a Low Salt Concentration

1999 ◽  
Vol 37 (6) ◽  
pp. 2047-2050 ◽  
Author(s):  
Ann Cathrine Petersson ◽  
Carl Kamme ◽  
Håkan Miörner
Keyword(s):  
Salt Concentration ◽  
Disk Diffusion ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Group V ◽  
Phage Group ◽  
Disk Diffusion Assay ◽  
Agar Dilution ◽  
Diffusion Assay

A separation between mecA + strains ofStaphylococcus aureus and strains lacking mecAwas achieved by the disk diffusion assay and the agar dilution method, utilizing disks containing 5 μg of oxacillin and inocula of approximately 5 × 105 CFU/spot, respectively, provided that agar with 0 to 0.5% NaCl and incubation at 30°C were employed. The 5-μg oxacillin disks clearly discriminated between borderline methicillin-susceptible and mecA +strains. The oxacillin MICs were more affected by the inoculum density and salt concentration than were the methicillin MICs, and oxacillin MICs of 4 to 16 μg/ml were obtained for strains lackingmecA. Significantly higher levels of β-lactamase production and reduced oxacillin susceptibilities were recorded for strains lacking mecA, in particular strains of phage group V, when agar with ≥2% NaCl was used than when agar with 0 to 0.5% NaCl was employed. The results indicate that the borderline methicillin-susceptible phenotype is a salt-dependent in vitro phenomenon of questionable clinical relevance.

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.

scholarly journals In Vitro Activity of Essential Oils Against Planktonic and Biofilm Cells of Extended-Spectrum β-Lactamase (ESBL)/Carbapenamase-Producing Gram-Negative Bacteria Involved in Human Nosocomial Infections

Antibiotics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 272 ◽  
Author(s):  
Ramona Iseppi ◽  
Alessandro Di Cerbo ◽  
Piero Aloisi ◽  
Mattia Manelli ◽  
Veronica Pellesi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Klebsiella Pneumoniae ◽  
Essential Oils ◽  
Disk Diffusion ◽  
Mentha Piperita ◽  
Thymus Vulgaris ◽  
Extended Spectrum ◽  
Disk Diffusion Assay ◽  
Diffusion Assay

The aim of this study was to analyze the antibacterial activity of four essential oils (EOs), Melaleuca alternifolia, Eucalyptus globulus, Mentha piperita, and Thymus vulgaris, in preventing the development and spread of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa and carbapenemase (KPC)-producing Klebsiella pneumoniae. A total of 60 strains were obtained from the stock collection from the Microbiology Laboratory of Hesperia Hospital, Modena, Italy. Twenty ESBL-producing E. coli, 5 K. pneumoniae, 13 KPC-producing K. pneumoniae, and 20 MBL-producing P. aeruginosa were cultured and reconfirmed as ESBL and carbapenamase producers. Polymerase chain reaction was used for the detection of genes responsible for antibiotic resistance (ESBL and KPC/MBL). Antibacterial activity of the EOs was determined using the agar disk diffusion assay, and minimal inhibitory concentrations (MICs) were also evaluated. Lastly, adhesion capability and biofilm formation on polystyrene and glass surfaces were studied in 24 randomly selected strains. M. alternifolia and T. vulgaris EOs showed the best antibacterial activity against all tested strains and, as revealed by agar disk diffusion assay, M. alternifolia was the most effective, even at low concentrations. This effect was also confirmed by MICs, with values ranging from 0.5 to 16 µg/mL and from 1 to 16 µg/mL, for M. alternifolia and T. vulgaris EOs, respectively. The EOs’ antibacterial activity compared to antibiotics confirmed M. alternifolia EO as the best antibacterial agent. T. vulgaris EO also showed a good antibacterial activity with MICs lower than both reference antibiotics. Lastly, a significant anti-biofilm activity was observed for the two EOs (*P < 0.05 and **P < 0.01 for M. alternifolia and T. vulgaris EOs, respectively). A good antibacterial and anti-biofilm activity of M. alternifolia and T. vulgaris EOs against all selected strains was observed, thus demonstrating a future possible use of these EOs to treat infections caused by ESBL/carbapenemase-producing strains, even in association with antibiotics.

scholarly journals Comparison of methods for the determination of antimicrobial resistance in Campylobacter spp. human and the food chain isolates

2008 ◽  
Vol 52 (No. 4) ◽  
pp. 169-174
Author(s):  
M. Holasova ◽  
R. Karpiskova ◽  
S. Karpiskova ◽  
V. Babak ◽  
J. Schlegelova
Keyword(s):  
Nalidixic Acid ◽  
Antimicrobial Agents ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
Microdilution Method ◽  
Study Results ◽  
Agar Dilution

With a microdilution method, using the commercial diagnostic test Sensititre Susceptibility Plates for Campylobacter MIC (Trek Diagnostic Systems, Cleveland, OH, USA), disk diffusion and agar dilution method, resistance to six antimicrobial agents were examined in a reference strain <i>Campylobacter jejuni</i> ATCC 33560 and 73 thermo-tolerant isolates of <i>Campylobacter</i> spp. For the microdilution method and all tested antimicrobial agents, our determined values of microbiological breakpoints of resistant strains were suggested as the minimum inhibitory concentration (MIC<sub>R</sub>) for ciprofloxacin &ge; 0.5, erythromycin &ge; 4, gentamicin &ge; 4, nalidixic acid &ge; 32 and tetracycline &ge; 4 &mu;g/ml. On the basis of our study results, strains resistant to clindamycin were MIC<sub>R</sub> &ge; 2 &mu;g/ml for the dilution methods and a zone diameter R ≤ 16 mm for the disk diffusion method. Comparison of the results of the resistance examination, a microdilution method and disk diffusion method with the reference agar dilution method, showed that all compared methods yielded identical results with the exception of the resistance determination in erythromycin and nalidixic acid. The errors were mostly the result of the interpretation criteria for MIC<sub>R</sub> of agar dilution method and different conditions of cultivation used. However, the compared methods, provide results comparable with the reference method having greater convenience of measurement.

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 Inaccuracy of the Disk Diffusion Method Compared with the Agar Dilution Method for Susceptibility Testing of Campylobacter spp.

2011 ◽  
Vol 50 (1) ◽  
pp. 52-56 ◽  
Author(s):  
Mirva Lehtopolku ◽  
Pirkko Kotilainen ◽  
Pauli Puukka ◽  
Ulla-Maija Nakari ◽  
Anja Siitonen ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
Agar Dilution ◽  
Campylobacter Spp

scholarly journals Telithromycin- and Fluoroquinolone-Resistant Streptococcus pneumoniae in Taiwan with High Prevalence of Resistance to Macrolides and β-Lactams: SMART Program 2001 Data

2003 ◽  
Vol 47 (7) ◽  
pp. 2145-2151 ◽  
Author(s):  
Po-Ren Hsueh ◽  
Lee-Jene Teng ◽  
Tsu-Lan Wu ◽  
Dine Yang ◽  
Wen-Kuei Huang ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Random Amplified Polymorphic Dna ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Time Period ◽  
High Prevalence ◽  
Agar Dilution ◽  
Different Parts

ABSTRACT There is a high prevalence of β-lactam- and macrolide-resistant Streptococcus pneumoniae in Taiwan. To understand the in vitro susceptibilities of recent isolates of S. pneumoniae to fluoroquinolones and telithromycin (which is not available in Taiwan), the MICs of 23 antimicrobial agents for 936 clinical isolates of S. pneumoniae isolated from different parts of Taiwan from 2000 to 2001 were determined by the agar dilution method. Overall, 72% of isolates were not susceptible to penicillin (with 61% being intermediate and 11% being resistant) and 92% were resistant to erythromycin. Telithromycin MICs were ≥1 μg/ml for 16% of the isolates, and for 99% of these isolates the MICs of all macrolides tested were ≥256 μg/ml; all of these isolates had the constitutive macrolide-lincosamide-streptogramin B phenotype. Eighty-eight percent of the isolates were resistant to three or more classes of drugs. The ciprofloxacin MICs were ≥4 μg/ml for six (0.6%) isolates from five patients collected in 2000 and 2001, and the levofloxacin MICs were ≥8 μg/ml for five of these isolates. Seven isolates for which ciprofloxacin MICs were ≥4 μg/ml, including one isolate recovered in 1999, belonged to three serotypes (serotype 19F, five isolates; serotype 23A, one isolate; and serotype 23B, one isolate). The isolates from the six patients for which ciprofloxacin MICs were ≥4 μg/ml had different pulsed-field gel electrophoresis profiles and random amplified polymorphic DNA patterns, indicating that no clonal dissemination occurred over this time period. Despite the increased rate of fluoroquinolone use, the proportion of pneumococcal isolates for which ciprofloxacin MICs were elevated (≥4 μg/ml) remained low. However, the occurrence of telithromycin resistance is impressive and raises concerns for the future.

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