scholarly journals In Vitro Susceptibility of Isolates of Francisella tularensis Types A and B from North America

2008 ◽  
Vol 52 (6) ◽  
pp. 2276-2278 ◽  
Author(s):  
Sandra K. Urich ◽  
Jeannine M. Petersen
Keyword(s):  
North America ◽  
Francisella Tularensis ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Laboratory Strain ◽  
In Vitro Susceptibility ◽  
Testing Method ◽  
The Common ◽  
Common Laboratory

ABSTRACT Due to concern that Francisella tularensis, the causative agent of tularemia, may be used as a bioterrorist weapon, the Clinical and Laboratory Standards Institute recently provided a susceptibility testing method with breakpoints. Here, 169 isolates (92 type A and 77 type B) from North America were tested against seven antimicrobial agents (streptomycin, gentamicin, tetracycline, doxycycline, ciprofloxacin, levofloxacin, and chloramphenicol) used for the treatment of tularemia. The MICs for all of the isolates fell within the susceptible range. In addition, all isolates had MICs for erythromycin of 0.5 to 4 μg/ml, in contrast to an MIC of >256 μg/ml for the common laboratory strain LVS (live vaccine strain).

Assessment of Laboratory Performance With Streptococcus pneumoniae Antimicrobial Susceptibility Testing in the United States

1999 ◽  
Vol 123 (4) ◽  
pp. 285-289 ◽  
Author(s):  
Gary V. Doern ◽  
Angela B. Brueggemann ◽  
Michael A. Pfaller ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
The United States ◽  
National Committee ◽  
In Vitro Susceptibility ◽  
Susceptibility Tests

Abstract Objective.—To assess the performance of clinical microbiology laboratories in the United States when conducting in vitro susceptibility tests with Streptococcus pneumoniae. Methods.—The results of a nationwide College of American Pathologists Proficiency Survey test sample, in which susceptibility testing of an isolate of S pneumoniae was performed, were assessed with respect to precision and accuracy. Results.—Wide variability was noted among participating laboratories with both minimum inhibitory concentration procedures and disk diffusion susceptibility tests when both methods were applied to S pneumoniae. Despite this high degree of variation, categorical interpretive errors were uncommon. Numerous laboratories reported results for antimicrobial agents that are not recommended by the National Committee for Clinical Laboratory Standards for tests with S pneumoniae. Conclusions.—Current susceptibility testing practices with S pneumoniae in the United States indicate limited precision and a tendency for laboratories to test and report results obtained with antimicrobial agents of questionable therapeutic value against this organism. Continued efforts to standardize susceptibility testing of S pneumoniae in the United States are warranted. In addition, modifications of existing interpretive criteria may be necessary.

Infection of the Subcutis and Skin of Cats with Rapidly Growing Mycobacteria: A Review of Microbiological and Clinical Findings

2000 ◽  
Vol 2 (1) ◽  
pp. 35-48 ◽  
Author(s):  
R Malik ◽  
D I Wigney ◽  
D Dawson ◽  
P Martin ◽  
G B Hunt ◽  
...  
Keyword(s):  
Oral Therapy ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Inhibitory Concentration ◽  
Clinical Findings ◽  
Disc Diffusion ◽  
In Vitro Susceptibility ◽  
In Vitro Susceptibility Testing

Mycobacteria were isolated and characterised from 49 cats with extensive infections of the subcutis and skin. Cats were generally between 3 and 10 years of age, and female cats were markedly over-represented. All isolates were rapid-growers and identified as either Mycobacteria smegmatis (40 strains) or M fortuitum (nine strains). On the basis of Etest for minimum inhibitory concentration and/or disc diffusion susceptibility testing, all strains of M smegmatis were susceptible to trimethoprim while all strains of M fortuitum were resistant. M smegmatis strains were typically susceptible to doxycycline, gentamicin and fluoroquinolones but not clarithromycin. All M fortuitum strains were susceptible to fluoroquinolones, and often also susceptible to gentamicin, doxycycline and clarithromycin. Generally, M smegmatis strains were more susceptible to antimicrobial agents than M fortuitum strains. Treatment of mycobacterial panniculitis involves long courses of antimicrobial agents, typically of 3–6 months, chosen on the basis of in vitro susceptibility testing and often combined with extensive surgical debridement and wound reconstruction. These therapies will result in effective cure of the disease. One or a combination of doxycycline, ciprofloxacin/enrofloxacin or clarithromycin are the drugs of choice for long-term oral therapy.

scholarly journals Discovery of beta-lactamase CMY-10 inhibitors for combination therapy against multi-drug resistant Enterobacteriaceae

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0244967
Author(s):  
Nousheen Parvaiz ◽  
Faisal Ahmad ◽  
Wenbo Yu ◽  
Alexander D. MacKerell ◽  
Syed Sikander Azam
Keyword(s):  
Combination Therapy ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Activity Assay ◽  
Primary Resistance ◽  
In Vitro Susceptibility ◽  
In Vitro Susceptibility Testing

β-lactam antibiotics are the most widely used antimicrobial agents since the discovery of benzylpenicillin in the 1920s. Unfortunately, these life-saving antibiotics are vulnerable to inactivation by continuously evolving β-lactamase enzymes that are primary resistance determinants in multi-drug resistant pathogens. The current study exploits the strategy of combination therapeutics and aims at identifying novel β-lactamase inhibitors that can inactivate the β-lactamase enzyme of the pathogen while allowing the β-lactam antibiotic to act against its penicillin-binding protein target. Inhibitor discovery applied the Site-Identification by Ligand Competitive Saturation (SILCS) technology to map the functional group requirements of the β-lactamase CMY-10 and generate pharmacophore models of active site. SILCS-MC, Ligand-grid Free Energy (LGFE) analysis and Machine-learning based random-forest (RF) scoring methods were then used to screen and filter a library of 700,000 compounds. From the computational screens 74 compounds were subjected to experimental validation in which β-lactamase activity assay, in vitro susceptibility testing, and Scanning Electron Microscope (SEM) analysis were conducted to explore their antibacterial potential. Eleven compounds were identified as enhancers while 7 compounds were recognized as inhibitors of CMY-10. Of these, compound 11 showed promising activity in β-lactamase activity assay, in vitro susceptibility testing against ATCC strains (E. coli, E. cloacae, E. agglomerans, E. alvei) and MDR clinical isolates (E. cloacae, E. alvei and E. agglomerans), with synergistic assay indicating its potential as a β-lactam enhancer and β-lactamase inhibitor. Structural similarity search against the active compound 11 yielded 28 more compounds. The majority of these compounds also exhibited β-lactamase inhibition potential and antibacterial activity. The non-β-lactam-based β-lactamase inhibitors identified in the current study have the potential to be used in combination therapy with lactam-based antibiotics against MDR clinical isolates that have been found resistant against last-line antibiotics.

scholarly journals In vitro biofilm formation and antibiotic susceptibility of Pseudomonas aeruginosa isolated from airways of patients with cystic fibrosis

2016 ◽  
Vol 85 (4) ◽  
pp. 245-253
Author(s):  
Jolanta Długaszewska ◽  
Marta Antczak ◽  
Izabella Kaczmarek ◽  
Renata Jankowiak ◽  
Malgorzata Buszkiewicz ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antibiotic Susceptibility ◽  
Biofilm Formation ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Testing Method ◽  
Airway Infections ◽  
Microdilution Broth

Background: Pseudomonas aeruginosa is the predominant cause of airway infections in patients with cystic fibrosis (CF) as a result of its ability to form biofilm. Resistance to antimicrobial agents is the most important feature of biofilm infection. The aim of this study was to evaluate biofilm formation and to compare antibiotic susceptibility of P. aeruginosa living in two modes of growth: planktonic and biofilm, isolated from respiratory tract of CF patients. Methods: Biofilm formation and biofilm susceptibility to antibiotics were determined using modified microtitere plate method. For susceptibility testing of planktonic culture to antibiotics serial microdilution broth method were used.Results: More than 95% of isolates were capable to form biofilm. Isolates grown as biofilms were more resistant to tested antibiotics compared to those grown planktonically. Ciprofloxacin showed the highest activity against P. aeruginosa biofilm. In contrast, no bacteriostatic activity was obtain for the highest concentration of piperacillin tested against most of P. aeruginosa strains growing in a biofilm (BIC > 4096 mg/L).Conclusions: Our study indicates the need to develop a standardized susceptibility testing method for biofilm mode of growth of pathogens. It appears that it is appropriate to introduce a biofilm susceptibility testing to routinely performed tests, as the effect of antibiotics on biofilm eradication may be variable and unpredictable.

In vitro biofilm formation and antibiotic susceptibility of Pseudomonas aeruginosa isolated from airways of patients with cystic fibrosis

10.20883/179 ◽  
2016 ◽  
Vol 85 (4) ◽  
pp. 245 ◽  
Author(s):  
Jolanta Długaszewska ◽  
Marta Antczak ◽  
Izabella Kaczmarek ◽  
Renata Jankowiak ◽  
Malgorzata Buszkiewicz ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antibiotic Susceptibility ◽  
Biofilm Formation ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Testing Method ◽  
Airway Infections ◽  
Microdilution Broth

Background: Pseudomonas aeruginosa is the predominant cause of airway infections in patients with cystic fibrosis (CF) as a result of its ability to form biofilm. Resistance to antimicrobial agents is the most important feature of biofilm infection. The aim of this study was to evaluate biofilm formation and to compare antibiotic susceptibility of P. aeruginosa living in two modes of growth: planktonic and biofilm, isolated from respiratory tract of CF patients. Methods: Biofilm formation and biofilm susceptibility to antibiotics were determined using modified microtitere plate method. For susceptibility testing of planktonic culture to antibiotics serial microdilution broth method were used.Results: More than 95% of isolates were capable to form biofilm. Isolates grown as biofilms were more resistant to tested antibiotics compared to those grown planktonically. Ciprofloxacin showed the highest activity against P. aeruginosa biofilm. In contrast, no bacteriostatic activity was obtain for the highest concentration of piperacillin tested against most of P. aeruginosa strains growing in a biofilm (BIC > 4096 mg/L).Conclusions: Our study indicates the need to develop a standardized susceptibility testing method for biofilm mode of growth of pathogens. It appears that it is appropriate to introduce a biofilm susceptibility testing to routinely performed tests, as the effect of antibiotics on biofilm eradication may be variable and unpredictable.

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