scholarly journals Error rates associated with the use of recently proposed breakpoints for testing Pseudomonas aeruginosa versus gentamicin, tobramycin, and amikacin by the standardized disk agar diffusion test.

1983 ◽  
Vol 24 (5) ◽  
pp. 764-770 ◽  
Author(s):  
B F Woolfrey ◽  
J M Fox ◽  
C O Quall ◽  
R T Lally
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Error Rates ◽  
Diffusion Test ◽  
Agar Diffusion ◽  
Agar Diffusion Test

scholarly journals Antimicrobial effect of 2% sodium hypochlorite and 2% chlorhexidine tested by different methods

2003 ◽  
Vol 14 (1) ◽  
pp. 58-62 ◽  
Author(s):  
Carlos Estrela ◽  
Rosane Galhardo Ribeiro ◽  
Cyntia R.A. Estrela ◽  
Jesus Djalma Pécora ◽  
Manoel Damião Sousa-Neto
Keyword(s):  
Sodium Hypochlorite ◽  
Culture Medium ◽  
Agar Plate ◽  
Antimicrobial Effect ◽  
Control Group ◽  
Diffusion Test ◽  
Exposure Test ◽  
Agar Diffusion ◽  
Direct Exposure ◽  
Agar Diffusion Test

The objective of this study was to analyze the antimicrobial effect of 2% sodium hypochlorite (NaOCl) and 2% chlorhexidine (CHX) by agar diffusion test and by direct exposure test. Five microorganisms: Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, and one mixture of these were used. These strains were inoculated in brain heart infusion (BHI) and incubated at 37ºC for 24 h. For the agar diffusion test (ADT), 18 Petri plates with 20 ml of BHI agar were inoculated with 0.1 ml of the microbial suspensions, using sterile swabs that were spread on the medium, obtaining growth in junction. Fifty-four paper disks (9 mm in diameter) were immersed in the experimental solutions for 1 min. Subsequently, three papers disks containing one of the substances were placed on the BHI agar surface in each agar plate. The plates were maintained for 1 h at room temperature, and then incubated at 37ºC for 48 h. The diameter of microbial inhibition was measured around the papers disks containing the substances. For the direct exposure test, 162 #50 sterile absorbent paper points were immersed in the experimental suspensions for 5 min, and were then placed on Petri plates and covered with one of the irrigant solutions, or with sterile distilled water (control group). After intervals of 5, 10 and 30 min, the paper points were removed from contact with the solutions and individually immersed in 7 ml of Letheen Broth, followed by incubation at 37ºC for 48 h. Microbial growth was evaluated by turbidity of the culture medium. A 0.1 ml inoculum obtained from the Letheen Broth was transferred to 7 ml of BHI, and incubated at 37ºC for 48 h. Bacterial growth was again evaluated by turbidity of the culture medium. Gram stain of BHI cultures was used for verification of contamination and growth was determined by macroscopic and microscopic examination. The best performance of antimicrobial effectiveness of NaOCl was observed in the direct exposure test, and of CHX was observed in the agar diffusion test. The magnitude of antimicrobial effect was influenced by the experimental methods, biological indicators and exposure time.

scholarly journals Resistance of nosocomial strains to antibacterial drugs and its link to biofilm formation

2017 ◽  
Vol 8 (4) ◽  
pp. 540-546
Author(s):  
T. V. Sklyar ◽  
K. V. Lavrentievа ◽  
Y. A. Alyonkina ◽  
A. M. Kolomoets ◽  
А. І. Vinnikov
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Clinical Practice ◽  
Biofilm Formation ◽  
Direct Relationship ◽  
Wide Distribution ◽  
Clinical Isolates ◽  
Diffusion Test ◽  
Antibacterial Drugs ◽  
Agar Diffusion Test

The problem of nosocomial infections is considered in connection with more frequent formation and wide distribution in clinical practice of new strains of hospital bacteria that have a cross-resistence to antibacterial drugs. The nosocomial agents were isolated from wounds and identified as Staphylococcus aureus and Pseudomonas aeruginosa. 72.0% of S. aureus strains and 61.5% of P. aeruginosa clinical isolates had the capability of forming biofilms. The sensitivity to antibiotics of all isolated strains was investigated with tne agar diffusion test. This method showed that all strains of S. aureus with the capability to form biofilms had resistence to erythromycin, gentamycin, ciprofloxacin and levofloxacin. The had the greatest sensitivity to klindamycin (90.3%), vancomycin (80.6%) and gatifloxacin (80.6% cultures). The strains of S. aureus with the capability to form biofilms were more resistent to antibiotics than strains of S. aureus without such properties. Only cefotaxim suppressed the growth of 75.0% of strains of staphylococci. All isolated strains of S. aureus without the capability to form biofilms were sensitive to doxycyclin, gentamycin, ciprofloxacin, levofloxacin and klindamycin. All clinical isolates of P. aeruginosa with capability to form biofilms had resistence to ampicillin, gentamycin, imipenem, cefotaxime and ceftriaxone. They were most sensitive (75.0%) to piperacillin and cefoperazone/sulbactam. The strains of P. aeruginosa without the capability to form biofilms kept the resistence to gentamycin, imipenem and ceftriaxone. They showed the greatest sensitivity (75.0%) to ciprofloxacin (80.0% isolates) and also to amikacin, ampicillin, meropenem, norfloxacin and cefotaxime (60.0% cultures). We investigated the minimum inhibitory concentrations of gentamycin and ciprofloxacin, which appeared higher for P. aeruginosa than for S. aureus. The most effective disinfectant against all isolated nosocomial agents without the capacity for biofilm formation was “Desactin” in a concentration 0.1% or 0.2%. For strains of staphylococci with this capability, the efficiency of “Desactin” went down by 9.7%. The best biocide effect against the strains of P. aeruginosa with the capability of forming biofilms was shown by 0.1% solution of “Neochlorine tabs”, which suppressed the growth of 75.0% of tested cultures. As a result, we detected a direct relationship between resistance to antibiotics and disinfectants and the capacities for biofilm formation among the nosocomial agents S. aureus and P. aeruginosa. 

scholarly journals Antimicrobial Potential of Strontium Hydroxide on Bacteria Associated with Peri-Implantitis

Antibiotics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 150
Author(s):  
Hatem Alshammari ◽  
Jessica Neilands ◽  
Gunnel Svensäter ◽  
Andreas Stavropoulos
Keyword(s):  
Antimicrobial Properties ◽  
Fusobacterium Nucleatum ◽  
Diffusion Test ◽  
Agar Diffusion ◽  
Antimicrobial Potential ◽  
Viability Assay ◽  
Patient Morbidity ◽  
Agar Diffusion Test ◽  
Zones Of Inhibition ◽  
Strontium Hydroxide

Background: Peri-implantitis due to infection of dental implants is a common complication that may cause significant patient morbidity. In this study, we investigated the antimicrobial potential of Sr(OH)2 against different bacteria associated with peri-implantitis. Methods: The antimicrobial potential of five concentrations of Sr(OH)2 (100, 10, 1, 0.1, and 0.01 mM) was assessed with agar diffusion test, minimal inhibitory concentration (MIC), and biofilm viability assays against six bacteria commonly associated with biomaterial infections: Streptococcus mitis, Staphylococcus epidermidis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Escherichia coli, and Fusobacterium nucleatum. Results: Zones of inhibition were only observed for, 0.01, 0.1, and 1 mM of Sr(OH)2 tested against P. gingivalis, in the agar diffusion test. Growth inhibition in planktonic cultures was achieved at 10 mM for all species tested (p < 0.001). In biofilm viability assay, 10 and 100 mM Sr(OH)2 showed potent bactericidal affect against S. mitis, S. epidermidis, A. actinomycetemcomitans, E. coli, and P. gingivalis. Conclusions: The findings of this study indicate that Sr(OH)2 has antimicrobial properties against bacteria associated with peri-implantitis.

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