Search Results

1 - 10 of 64 items :

  • "disc diffusion method" x
Clear All

Abstract

The antifungal activities of 14 selected essential oils (at the concentrations of 0.5 %, 5 %, and 30 %) against the yeast Malassezia pachydermatis (18 isolates and one reference strain) were investigated. The isolates of M. pachydermatis were obtained from swabs of external ear canals of healthy dogs using sterile swabs. The determination of the efficacy was based on a modified disc diffusion method (CLSI M44-A2). The best antifungal efficacy (100 %) was shown by clove, cinnamon and oregano at the concentration of 30 %; less significant efficacy was shown at the concentration of 5 % (38 %, 33 % and 5 %, respectively). Satureja inhibited the growth of Malassezia (efficacy of 16 %) only at the concentration of 30 %. Bergamot, lavender, juniper, cedar, sage, tea-tree, grapefruit, pine, chamomile and yarrow essential oils were not able to form inhibition zones as defined in the methodology used (greater or equal to 15 mm) in all concentrations used. Therefore, according to the interpretation criterion, they were considered ineffective. In all cases, the concentration of 0.5 % was not effective against the growth of Malassezia yeasts.

Abstract

The purpose of this study was to detect the antibiotic resistance of forty-one Escherichia coli isolates from the intestinal contents of slaughtered broiler chickens using the disk diffusion method according to Kirby-Bauer. Mueller-Hinton agar plates were inoculated with 0.1 ml overnight broth cultures of individual E. coli isolates and the disks with the following concentrations of antibiotics were applied onto them: ampicillin (10 μg), cefotaxime (30 μg), gentamicin (10 μg), streptomycin (10 μg), azithromycin (15 μg), tetracycline (30 μg), ciprofloxacin (30 μg) and levofloxacin (3 μg). After the incubation at 37 °C for 16—18 hours, the inhibition zones were measured and interpreted in accordance with the Clinical and Laboratory Standard Institute (CLSI) zone diameter breakpoints. Almost all E. coli isolates showed resistance to tetracycline (92.68 %), most of them were resistant to gentamicin (75.61 %) and levofloxacine (70.73 %). Phenotypic resistance to tetracycline was further confirmed with the help of the Polymerase Chain Reaction (PCR) procedure focused on the presence of specific tet(A) and tet(B) genes. These genes were detected in all 41 E. coli isolates. On the contrary, E. coli isolates were highly susceptible to both azithromycin and streptomycin. In conclusion, the study highlighted the role of commensal E. coli bacteria isolated from the intestines of broiler chickens as an important reservoir of tetracycline resistance genes.

Summary

Introduction: For centuries, mosses have been used in traditional medicine due to their antibacterial, antifungal, and antiviral activities. Objective: The present study was designed to evaluate the antibacterial activity of ethanolic extracts obtained from 12 moss species: Brachythecium albicans, Bryum argenteum, Ceratodon purpureus, Dicranum scoparium, Dryptodon pulvinatus, Orthotrichum anomalum, Oxyrrhynchium hians, Plagiomnium undulatum, Polytrichum juniperinum, P. piliferum, Schistidium crassipilum, and Syntrichia ruralis. Methods: The antimicrobial activity of extracts was investigated against three Gram(+) bacteria (Enterococcus faecalis, Staphylococcus aureus, and Streptococcus pyogenes) and two Gram(-) bacteria (Escherichia coli and Klebsiella pneumoniae), using the agar disc-diffusion method. Results: The high activity against all investigated bacteria was determined for extracts of D. pulvinatus, P. undulatum, B. argenteum, S. crassipilum, O. anomalum (mean inhibition zone: 11.3-13.1 mm) and to a lesser extent in the case of D. scoparium (8.3 mm). Extracts from P. juniperinum and P. piliferum showed activity only against Gram-positive bacteria, with an inhibition zone from 7.3 to 9.7 mm. Four species: B. albicans, C. purpureus, O. hians, and S. ruralis had not antibacterial properties. Conclusions: The obtained results indicate that mosses could be a significant source of antibacterial agents. For the first time, we presented antibacterial activity of ethanolic extracts from S. crassipilum and O. anomalum.

fluconazole and voriconazole (r = -0.47; P < 0.001 and r = -0.75; P < 0.001, respectively). The total percentage agreement of the ET and DD determinations, compared with the standard reference BMD-MIC values for the two antifungal agents, exceeded 90% as summarized in Table 2 . Table 2 Errors with the E-test and disk diffusion methods compared with broth microdilutions for fluconazole and voriconazole Method Category Fluconazole by BMD No. of strains Total agreement (%) Voriconazole by BMD No. of strains Total agreement (%) S I R VME ME mE S I R VME ME mE ET S 61 0 0

Abstract

The aim of the present study was to detect the antibacterial activity of medicinal plants against fish microflora. A total of 4 ethanolic extracts of 6 plant species were collected from local environments of Slovakia and screened for antibacterial activity against bacterial microflora. Extracts of Melissa officinalis L., Mentha piperita L., Origanum vulgare L. and Malva mauritiana were used. Bacterial strains were isolated from common bleak (Alburnus alburnus) and common rudd (Scardinius erythrophthalmus) of Latvian origin. All bacterial strains were identified with the Matrix- Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). Among fish microflora, Acinetobacter pittii, A. baumannii, Buttiauxella agrestis, Delftia acidovorans, Enterobacter cloacae, Serratia liquefaciens, Pseudomonas alcaligenes, Ps. oryzihabitans, Staphylococcus epidermidis, St. caprae, Pantoea agglomerans, Lelliottia amnigena, Providencia rettgeri, Escherichia coli and Rahnella aquatilis were identified. It has been shown that all plant extracts exhibit different degrees of antimicrobial activity against the tested bacteria. All bacterial strains in the present study were moderate sensitive to all extracts applied. The strongest antimicrobial effect of Malva mauritiana and Melissa officinalis L. against Pseudomonas oryzihabitans (6.67±1.53 resp. 9.67±0.58 mm) were found. The best antimicrobial activity of Mentha piperita L. was against Staphylococcus epidermis (7.33±0.58 mm) and strongest antimicrobial effect of Origanum vulgare L. was same against two bacterial strains Enterobacter cloacae and Serratia liquefaciens (9.67±0.58 mm).

from broiler chickens solated at an Irish poultry processing plant. Lett Appl Microbiol. 2003; 36:277-81. 10.1046/j.1472-765X.2003.01308.x 24. Luangtongkum T, Morishita TY, El-Tayeb A, Ison AJ, Zhang Q. Comparison of antimicrobial susceptibility testing of Campylobacter species by the agar dilution and the agar disk diffusion methods. J Clin Microbiol. 2007; 45:590-4. 10.1128/JCM.00986-06 25. Nachamkin I, Engberg J, Aarestrup FM. Diagnosis and antimicrobial susceptibility of Campylobacter species. In: Nachamkin I, Blaser M J, editors. Campylobacter. Washington, DC

and existence of integrons. Materials and methods Bacterial strains Between April and July 2013, 111 anonymized nonduplicate E. coli isolates from urine samples were collected from 4 hospitals and 2 private clinical laboratories of Alborz province, Karaj city. Isolates were identified as E. coli based on standard biochemical tests [ 7 ]. Antimicrobial susceptibility assay The susceptibilities of all isolates to 19 different antibiotics were determined using a Kirby–Bauer disk diffusion method, as suggested by the Clinical and Laboratory Standards Institute [ 8

, and K. rhinoscleromatis ) that had been isolated in a previous study [ 4 ]. Antibiotic resistance testing and antibiotyping The antibiotic resistance of Klebsiella species to six different antibiotics and combinations (SXT: trimethoprim-sulfamethoxazole (1.25/23.75 μg), SAM: ampicillin-sulbactam (10/10 μg), IPM: imipenem (10 μg), TZP: piperacillin tazobactam (100/10 μg), CIP: ciprofloxacin (5 μg), CZ: ceftizoxime (30 g)) were assessed using a Kirby–Bauer disc diffusion method. Klebsiella spp. that showed the same antibiotic resistance pattern, were grouped in

(CRO) (10 μg) was assessed by disc-diffusion methods according to National Committee for Clinical Laboratory Standards (NCCLS). The strains were classified as resistant (R), intermediate (I), or sensitive (S), according to the zone table published by the Clinical and Laboratory Standards Institute (940 West Valley Road, Suite 1400, Wayne, PA, USA). Biofilm formation The crystal violet binding assay described by O’Toole was used with some modifications to determine biofilm formation by P. mirabilis strains [ 11 ]. Briefly, bacterial cells were inoculated into brain

Abstract

Background: Bacopa monnieri (Linn) Pennell (Scrophulariaceae) is widely distributed in tropical regions of Asia, and used in the treatment of cough or as an antiseptic. The traditional use of this plant suggests its possible antibacterial properties, but its efficacy has not been examined yet. Objective: Evaluate the antibacterial efficacy against pathogenic bacteria using the disk diffusion method. Materials and methods: Five different concentrations (500 μg, 1, 2, 5, 10, and 15 mg/mL) of crude leaf extracts of Bacopa monnieri (L.) Pennell were tested for antibacterial efficacy against seven Gram-positive and 11 Gramnegative bacteria. The sensitivity of plant fractions was tested using the disk diffusion method. Results: Maximum activity was revealed by ethyl acetate and methanol extracts, followed by aqueous, benzene, and petrol extracts. Phyto-chemical analysis of the plant leaf showed the presence of alkaloids, flavonoids, and saponins. Conclusion: This plant may be effective for treatment of different pathogenic diseases.