scholarly journals Comparison of Three Methods for Testing Azole Susceptibilities of Candida albicans Strains Isolated Sequentially from Oral Cavities of AIDS Patients

1998 ◽  
Vol 36 (6) ◽  
pp. 1578-1583 ◽  
Author(s):  
Anna Maria Tortorano ◽  
Maria Anna Viviani ◽  
Francesco Barchiesi ◽  
Daniela Arzeni ◽  
Anna Lisa Rigoni ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Clinical Laboratory ◽  
Reference Method ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Aids Patients ◽  
Testing Procedures ◽  
Broth Microdilution Method ◽  
Mean Differences

Three susceptibility testing procedures were compared to determine fluconazole, itraconazole, and ketoconazole MICs against 47Candida albicans strains isolated sequentially from the oral cavities of five AIDS patients undergoing azole therapy. They included the broth microdilution method (BM), performed according to the National Committee for Clinical Laboratory Standards’ tentative standard, the agar dilution method (AD), and the Etest; the latter two tests were performed both in Casitone agar (AD-Cas and Etest-Cas) and in RPMI (AD-RPMI and Etest-RPMI). Twenty-four- and 48-h MICs obtained by AD and Etest were compared with 48-h MICs obtained by BM. The MICs of all the azoles determined by BM were usually lower than those obtained by the other methods, mainly due to different reading criteria. In order to assess the most appropriate way of evaluating the agreement of MICs obtained by different methods with those produced by the proposed reference method (BM), we used the mean differences calculated according to Bland and Altman’s method. Comparison of fluconazole MICs obtained by BM and AD-Cas yielded a mean difference of 3, and the percentages of agreement within ±2 dilutions were 98 and 100% at 24 and 48 h, respectively. For ketoconazole and itraconazole MICs, lower mean differences were noted, and agreement ranged from 96 to 100%. Agreement between the AD-RPMI and BM results was poor for all azoles, and an increase in MICs was always observed between the 1st- and 2nd-day readings. Similarly, Etest-Cas gave better agreement with BM than did Etest-RPMI for all the azoles. BM, AD-Cas, and Etest-Cas each demonstrated a progressive increase in fluconazole MICs against strains isolated sequentially from a given patient, in accordance with the decreased clinical response to fluconazole.

scholarly journals Susceptibility Testing of Anaerobic Bacteria: Evaluation of the Redesigned (Version 96) bioMérieux ATB ANA Device

1999 ◽  
Vol 37 (6) ◽  
pp. 1824-1828 ◽  
Author(s):  
L. Dubreuil ◽  
I. Houcke ◽  
E. Singer
Keyword(s):  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Anaerobic Bacteria ◽  
Reference Method ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
French Society ◽  
Antibiotic Susceptibilities ◽  
Agar Dilution

We compared the susceptibility results for 200 clinical anaerobes with nine antibiotics obtained by using a new ATB ANA (bioMérieux) device against those obtained by the National Committee for Clinical Laboratory Standards (NCCLS) standard agar dilution method. For better evaluation of the device, we added some resistant Bacteroides fragilis group strains from our own collection: 3, 6, and 12 strains that were resistant to imipenem, ticarcillin plus clavulanic acid, and co-amoxiclav, respectively, and 2 other strains with decreased susceptibility to metronidazole. For some strains that did not grow on ATB S medium, tests were performed by using West-Wilkins medium supplemented with 1.5% agar. The new ATB ANA device made clinical categorization of the investigated strains possible, according to French (Committee of the Antibiogram of the French Society of Microbiology) or U.S. (NCCLS) breakpoints, with the following respective results: category agreement, 94.3 and 94.9%; minor errors, 4.8 and 3.8%; major errors, 0.4 and 0.8%; and very major errors 4.6 and 4.2%. The ATB ANA device was able to detect low-level metronidazole-resistant B. fragilis strains according to the French breakpoints but not the NCCLS ones. For B. fragilis and β-lactamase-positive Prevotellastrains, the clustering effect of amoxicillin MICs around the French breakpoints led to more frequent minor errors. ATB ANA is a very convenient method to determine the antibiotic susceptibilities of anaerobes. Results obtained by ATB ANA correlated well with those obtained by the reference method.

scholarly journals Fluconazole Susceptibility Testing of Cryptococcus neoformans: Comparison of Two Broth Microdilution Methods and Clinical Correlates among Isolates from Ugandan AIDS Patients

1998 ◽  
Vol 36 (10) ◽  
pp. 2874-2876 ◽  
Author(s):  
C. J. Jessup ◽  
M. A. Pfaller ◽  
S. A. Messer ◽  
J. Zhang ◽  
M. Tumberland ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Clinical Laboratory ◽  
Reference Method ◽  
National Committee ◽  
Yeast Nitrogen Base ◽  
Broth Microdilution ◽  
Aids Patients ◽  
In Vitro Susceptibility ◽  
Nitrogen Base ◽  
Broth Microdilution Method

We compared the yeast nitrogen base (YNB) broth microdilution method with the National Committee for Clinical Laboratory Standards (NCCLS) M27-A microdilution reference method for measuring the in vitro susceptibility of Cryptococcus neoformans isolates to fluconazole. A total of 149 isolates of C. neoformans var.neoformans from Ugandan AIDS patients was tested by both methods. An overall agreement of 88% between the two microdilution methods was observed. All isolates grew well in both RPMI 1640 and YNB media, and MICs could be read after 48 h of incubation by both methods. The range of fluconazole MICs obtained with the YNB method was broader than that obtained with the NCCLS method. The extended range of MICs provided by the YNB method may be of clinical value, as it appears that the clinical outcome may be better among patients infected with strains inhibited by lower concentrations of fluconazole as determined by the YNB method. The YNB method appears to be a viable option for testing C. neoformans against fluconazole.

Fluoroquinolone E-Testing against Pseudomonas Aeruginosa and Streptococcus Pneumoniae

2002 ◽  
Vol 18 (5) ◽  
pp. 241-247
Author(s):  
Eric G Sahloff ◽  
Benjamin P Smith ◽  
Steven J Martin
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Streptococcus Pneumoniae ◽  
Clinical Laboratory ◽  
Reference Method ◽  
Test Methods ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Drug Activity ◽  
Agar Dilution

Objectives and Design: The use of fluoroquinolones has increased against antibiotic-resistant pathogens such as Streptococcus pneumoniae and Pseudomonas aeruginosa. The E-test (AB Biodisk, Solna, Sweden) is now commonly used for susceptibility testing of fluoroquinolones against these organisms. The purpose of the present study was to evaluate the accuracy and correlation of minimum inhibitory concentrations (MICs) determined by E-testing with a National Committee for Clinical Laboratory Standards reference standard, agar-dilution MIC testing. E-test and agar dilution MICs were compared for ciprofloxacin, levofloxacin, gatifloxacin, and moxifloxacin against clinical isolates of S. pneumoniae (n = 53) and P. aeruginosa (n = 62). Main Outcome Measures: MICs were determined by use of agar dilution and E-test methods. Essential agreement was defined as MICs from both methods within ± 1 log2 dilution. Categorical agreement compared MIC interpretations: susceptible, intermediate, or resistant. Categorical disagreement between methods was reported as very major, major, or minor errors. Results: E-tests produced lower MICs than the reference method for ciprofloxacin, gatifloxacin, and moxifloxacin versus P. aeruginosa. For S. pneumoniae, E-test MICs tended to be higher for all fluoroquinolones. The best correlation between testing methods was seen with levofloxacin. Essential agreement occurred more frequently with P. aeruginosa in the lower range of MICs and with S. pneumoniae in the higher range of MICs. Categorical agreement was greater than 90% for the 460 comparisons. Two very major errors (false-susceptible) occurred for gatifloxacin versus P. aeruginosa. Conclusions: For the determination of fluoroquinolone susceptibility against S. pneumoniae and P. aeruginosa, E-testing is a simple tool for clinical use, and few very major or major errors in susceptibility interpretation occur for either organism. For determining fluoroquinolone MICs, E-testing may overestimate drug activity against P. aeruginosa and underestimate drug activity versus S. pneumoniae compared with the agar dilution method. These differences could affect appropriate antimicrobial selection, leading to suboptimal outcomes.

Use of spectrophotometric reading for in vitro antifungal susceptibility testing ofAspergillusspp.

1999 ◽  
Vol 45 (10) ◽  
pp. 871-874 ◽  
Author(s):  
Eric Dannaoui ◽  
Florence Persat ◽  
Marie-France Monier ◽  
Elisabeth Borel ◽  
Marie-Antoinette Piens ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Aspergillus Species ◽  
National Committee ◽  
Broth Microdilution Method

A comparative study of visual and spectrophotometric MIC endpoint determinations for antifungal susceptibility testing of Aspergillus species was performed. A broth microdilution method adapted from the National Committee for Clinical Laboratory Standards (NCCLS) was used for susceptibility testing of 180 clinical isolates of Aspergillus species against amphotericin B and itraconazole. MICs were determined visually and spectrophotometrically at 490 nm after 24, 48, and 72h of incubation, and MIC pairs were compared. The agreement between the two methods was 99% for amphotericin B and ranged from 95 to 98% for itraconazole. It is concluded that spectrophotometric MIC endpoint determination is a valuable alternative to the visual reference method for susceptibility testing of Aspergillus species.Key words: antifungal, susceptibility testing, Aspergillus, spectrophotometric reading.

scholarly journals Correlation of Oxacillin MIC with mecAGene Carriage in Coagulase-Negative Staphylococci

2000 ◽  
Vol 38 (2) ◽  
pp. 752-754 ◽  
Author(s):  
Zafar Hussain ◽  
Luba Stoakes ◽  
Viki Massey ◽  
Deb Diagre ◽  
Viivi Fitzgerald ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Clinical Laboratory ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Coagulase Negative Staphylococci ◽  
Methicillin Resistant ◽  
Mueller Hinton ◽  
Mueller Hinton Agar ◽  
Agar Dilution

The National Committee for Clinical Laboratory Standards has recently changed the oxacillin breakpoint from ≥4 mg/liter to ≥0.5 mg/liter to detect methicillin-resistant coagulase-negative staphylococci (CoNS) because the previous breakpoint lacked sensitivity. To determine the correlation between the new oxacillin breakpoint and the presence of themecA gene, 493 CoNS of 11 species were tested. The presence of the mecA gene was determined by PCR, and oxacillin susceptibility was determined by the agar dilution method with Mueller-Hinton agar containing 2% NaCl and oxacillin (0.125 to 4.0 mg/liter). The new breakpoint correctly classified all CoNS strains with mecA as methicillin resistant and strains ofStaphylococcus epidermidis, S. haemolyticus, and S. hominiswithout mecA as methicillin susceptible. The breakpoint of ≥0.5 mg/liter was not specific for S. cohnii, S. lugdunensis, S. saprophyticus, S. warneri, and S. xylosus, in that it categorized 70 of 74 strains of these species withoutmecA (94.6%) as methicillin resistant. The results of this study indicate that the new oxacillin breakpoint accurately identifies strains of CoNS with mecAbut is not specific for strains of certain species of CoNS withoutmecA.

scholarly journals In Vitro Activity of Gemifloxacin (SB 265805) against Anaerobes

1999 ◽  
Vol 43 (9) ◽  
pp. 2231-2235 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
Yumi Warren ◽  
Kerin Tyrrell ◽  
C. Vreni Merriam
Keyword(s):  
Clinical Laboratory ◽  
Fusobacterium Nucleatum ◽  
Fusobacterium Necrophorum ◽  
Penicillin G ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Prevotella Melaninogenica ◽  
Amoxicillin Clavulanate

ABSTRACT Gemifloxacin mesylate (SB 265805), a new fluoronaphthyridone, was tested against 359 recent clinical anaerobic isolates by the National Committee for Clinical Laboratory Standards reference agar dilution method with supplemented brucella blood agar and an inoculum of 105 CFU/spot. Comparative antimicrobials tested included trovafloxacin, levofloxacin, grepafloxacin, sparfloxacin, sitafloxacin (DU-6859a), penicillin G, amoxicillin clavulanate, imipenem, cefoxitin, clindamycin, and metronidazole. The MIC50 and MIC90 (MICs at which 50 and 90% of the isolates were inhibited) of gemifloxacin against various organisms (with the number of strains tested in parentheses) were as follows (in micrograms per milliliter): for Bacteroides fragilis (28), 0.5 and 2; forBacteroides thetaiotaomicron (24), 1 and 16; forBacteroides caccae (12), 1 and 16; for Bacteroides distasonis (12), 8 and >16; for Bacteroides ovatus(12), 4 and >16; for Bacteroides stercoris (12), 0.5 and 0.5; for Bacteroides uniformis (12), 1 and 4; forBacteroides vulgatus (11), 4 and 4; for Clostridium clostridioforme (15), 0.5 and 0.5; for Clostridium difficile (15), 1 and >16; for Clostridium innocuum(13), 0.125 and 2; for Clostridium perfringens (13), 0.06 and 0.06; for Clostridium ramosum (14), 0.25 and 8; forFusobacterium nucleatum (12), 0.125 and 0.25; forFusobacterium necrophorum (11), 0.25 and 0.5; forFusobacterium varium (13), 0.5 and 1; forFusobacterium spp. (12), 1 and 2; forPeptostreptococcus anaerobius (13), 0.06 and 0.06; forPeptostreptococcus asaccharolyticus (13), 0.125 and 0.125; for Peptostreptococcus magnus (14), 0.03 and 0.03; forPeptostreptococcus micros (12), 0.06 and 0.06; forPeptostreptococcus prevotii (14), 0.06 and 0.25; forPorphyromonas asaccharolytica (11), 0.125 and 0.125; forPrevotella bivia (10), 8 and 16; for Prevotella buccae (10), 2 and 2; for Prevotella intermedia (10), 0.5 and 0.5; and for Prevotella melaninogenica (11), 1 and 1. Gemifloxacin mesylate (SB 265805) was 1 to 4 dilutions more active than trovafloxacin against fusobacteria and peptostreptococci, and the two drugs were equivalent against clostridia and P. asaccharolytica. Gemifloxacin was equivalent to sitafloxacin (DU 6859a) against peptostreptococci, C. perfringens, andC. ramosum, and sitafloxacin was 2 to 3 dilutions more active against fusobacteria. Sparfloxacin, grepafloxacin, and levofloxacin were generally less active than gemifloxacin against all anaerobes.

scholarly journals Department of Microbiology, Bangladesh Agricultural University, Mymensingh

2016 ◽  
Vol 2 (2) ◽  
pp. 3-6
Author(s):  
Nahida Akther Zahan ◽  
Md. Akram Hossain ◽  
AKM Shamsuzzaman ◽  
AKM Musa ◽  
Md. Chand Mahamud ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Methicillin Resistance ◽  
Meca Gene ◽  
Toxin Production ◽  
Latex Agglutination ◽  
Diffusion Method ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method

The study was done to detect different exotoxins among the strains of Staphylococcus aureus isolated in the department of Microbiology, Mymensingh Medical College in collaboration with the Department of Medicine under the Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh between the periods from July, 2006 to June, 2007. A total of 40 S. aureus isolates investigated in this study were identified by standard microbiological techniques. Antimicrobial susceptibility of the isolates to Oxacillin was carried out by disk diffusion method as per recommendation of the National Committee for Clinical Laboratory Standards. Any isolate showing resistance to Oxacillin was tested again by agar dilution method to determine minimum inhibitory concentration (MIC) of Methicillin. All strains were also tested for mecA gene by Polymerase Chain Reaction (PCR) for confirmation of Methicillin resistance. Enterotoxin (A-D) and Toxic Shock Syndrome Toxin-1 (TSST-1) were detected by Reverse Passive Latex Agglutination (RPLA) test. Out of 40 S. aureus isolates, 7 (17.5%) Methicillin Resistant S. aureus (MRSA), 1 (2.5%) Methicillin Sensitive S. aureus (MSSA) produced Staphylococcal Enterotoxin A (SE-A) and 1 MRSA isolate was positive for TSST-1. In case of combined toxin production among the S. aureus isolates, 2 (5%) MSSA were found to produce SE-A and SE-B, 2 (5%) MSSA produced SE-C and SE-D, and 1 (2.5%) MRSA, 1 (2.5%) MSSA produced SE-C and TSST-1.Bangladesh J Med Microbiol 2008; 02 (02): 3-6

scholarly journals Modified agar dilution susceptibility testing method for determining in vitro activities of antifungal agents, including azole compounds.

1997 ◽  
Vol 41 (6) ◽  
pp. 1349-1351 ◽  
Author(s):  
T Yoshida ◽  
K Jono ◽  
K Okonogi
Keyword(s):  
Antifungal Agents ◽  
Clinical Laboratory ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution ◽  
Weak Growth ◽  
High Concentrations ◽  
Broth Dilution

In vitro activities of antifungal agents, including azole compounds, against yeasts were easily determined by using RPMI-1640 agar medium and by incubating the plates in the presence of 20% CO2. The end point of inhibition was clear by this method, even in the case of azole compounds, because of the almost complete inhibition of yeast growth at high concentrations which permitted weak growth of some Candida strains by traditional methods. MICs obtained by the agar dilution method were similar to those obtained by the broth dilution method proposed by the National Committee for Clinical Laboratory Standards.

scholarly journals Evaluation of Etest and macrodilution broth method for antifungal susceptibility testing of Candida sp strains isolated from oral cavities of AIDS patients

2002 ◽  
Vol 44 (3) ◽  
pp. 121-125 ◽  
Author(s):  
Maria do Rosário R. SILVA ◽  
Márcio R. COSTA ◽  
André T.B. MIRANDA ◽  
Orionalda de F.L. FERNANDES ◽  
Carolina R. COSTA ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Resistant Isolate ◽  
National Committee ◽  
Aids Patients ◽  
Candida Sp ◽  
Sensitivity Evaluation ◽  
Broth Macrodilution

A comparison of the Etest and the reference broth macrodilution susceptibility test for fluconazole, ketoconazole, itraconazole and amphotericin B was performed with 59 of Candida species isolated from the oral cavities of AIDS patients. The Etest method was performed according to the manufacturer's instructions, and the reference method was performed according to National Committee for Clinical Laboratory Standards document M27-A guidelines. Our data showed that there was a good correlation between the MICs obtained by the Etest and broth dilution methods. When only the MIC results at ± 2 dilutions for both methods were considered, the agreement rates were 90.4% for itraconazole, ketoconazole and amphotericin B and 84.6% for fluconazole of the C. albicans tested. In contrast, to the reference method, the Etest method classified as susceptible three fluconazole-resistant isolates and one itraconazole-resistant isolate, representing four very major errors. These results indicate that Etest could be considered useful for antifungal sensitivity evaluation of yeasts in clinical laboratories.

scholarly journals Multicenter Comparison of the Sensititre YeastOne Colorimetric Antifungal Panel with the National Committee for Clinical Laboratory Standards M27-A Reference Method for Testing Clinical Isolates of Common and Emerging Candidaspp., Cryptococcus spp., and Other Yeasts and Yeast-Like Organisms

1999 ◽  
Vol 37 (3) ◽  
pp. 591-595 ◽  
Author(s):  
A. Espinel-Ingroff ◽  
M. Pfaller ◽  
S. A. Messer ◽  
C. C. Knapp ◽  
S. Killian ◽  
...  
Keyword(s):  
Amphotericin B ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Clinical Isolates ◽  
National Committee ◽  
Hansenula Anomala ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Blastoschizomyces Capitatus

National Committee for Clinical Laboratory Standards (NCCLS) standard guidelines are available for the antifungal susceptibility testing of common Candida spp. and Cryptococcus neoformans, but NCCLS methods may not be the most efficient and convenient procedures for use in the clinical laboratory. MICs of amphotericin B, fluconazole, flucytosine, itraconazole, and ketoconazole were determined by the commercially prepared Sensititre YeastOne Colorimetric Antifungal Panel and by the NCCLS M27-A broth microdilution method for 1,176 clinical isolates of yeasts and yeast-like organisms, including Blastoschizomyces capitatus, Cryptococcus spp., 14 common and emerging species of Candida, Hansenula anomala,Rhodotorula spp., Saccharomyces cerevisiae,Sporobolomyces salmonicolor, and Trichosporon beigelii. Colorimetric MICs of amphotericin B corresponded to the first blue well (no growth), and MICs of the other agents corresponded to the first purple or blue well. Three comparisons of MIC pairs by the two methods were evaluated to obtain percentages of agreement: 24- and 48-h MICs and 24-h colorimetric versus 48-h reference MICs. The best performance of the YeastOne panel was with 24-h MICs (92 to 100%) with the azoles and flucytosine for all the species tested, with the exception of C. albicans (87 to 90%). For amphotericin B, the best agreement between the methods was with 48-h MIC pairs (92 to 99%) for most of the species tested. The exception was for isolates ofC. neoformans (76%). These data suggest the potential value of the YeastOne panel for use in the clinical laboratory.

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