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 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 Susceptibilities of bovine summer mastitis bacteria to antimicrobial agents.

1996 ◽  
Vol 40 (1) ◽  
pp. 157-160 ◽  
Author(s):  
H Jousimies-Somer ◽  
S Pyörälä ◽  
A Kanervo
Keyword(s):  
Antimicrobial Agents ◽  
Anaerobic Bacteria ◽  
Fusobacterium Necrophorum ◽  
Penicillin G ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Beta Lactamase ◽  
Bacterial Isolates ◽  
Amoxicillin Clavulanate ◽  
Agar Dilution

The susceptibility to 9 antimicrobial agents of 32 aerobic bacterial isolates and to 10 antimicrobial agents of 37 anaerobic bacterial isolates from 23 cases of bovine summer mastitis (16 Actinomyces pyogenes isolates, 8 Streptococcus dysgalactiae isolates, 3 S. uberis isolates, 3 S. acidominimus isolates, 2 Streptococcus spp., 15 Peptostreptococcus indolicus isolates, 10 Fusobacterium necrophorum isolates, and 12 isolates of anaerobic gram-negative rods) was determined by the agar dilution method. All isolates except one Bacteroides fragilis isolate (beta-lactamase producer) were susceptible to penicillin G, amoxicillin, amoxicillin-clavulanate, cefoxitin, clindamycin, and chloramphenicol (the B. fragilis strain was susceptible to the last four), which had MICs at which 90% of isolates were inhibited (MIC90s) of < or = 0.06, < or = 0.06, < or = 0.06 0.25, < or = 0.06, and 4.0 micrograms/ml, respectively. Spiramycin was active against the gram-positive aerobes (MIC90, 1.0 microgram/ml) but not against the anaerobes (MIC90, 16.0 micrograms/ml). Similar trends were noted for susceptibilities of aerobic and anaerobic bacteria to ofloxacin (MIC90s, 2.0 and 8 micrograms/ml, respectively). Occasional strains of aerobic streptococci were resistant to oxytetracycline, but all anaerobes were susceptible. Tinidazole was active against all anaerobes (MIC90, 2.0 micrograms/ml). beta-Lactamase was produced only by the B. fragilis isolate.

scholarly journals Doripenem versus Pseudomonas aeruginosa In Vitro: Activity against Characterized Isolates, Mutants, and Transconjugants and Resistance Selection Potential

2004 ◽  
Vol 48 (8) ◽  
pp. 3086-3092 ◽  
Author(s):  
Shazad Mushtaq ◽  
Yigong Ge ◽  
David M. Livermore
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clinical Laboratory ◽  
Acquired Resistance ◽  
Single Step ◽  
Cross Resistance ◽  
National Committee ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Resistant Mutants

ABSTRACT Doripenem is a broad-spectrum parenteral carbapenem under clinical development in Japan and North America. Its activities against (i) Pseudomonas aeruginosa isolates with graded levels of intrinsic efflux-type resistance, (ii) mutants with various combinations of AmpC and OprD expression, (iii) PU21 transconjugants with class A and D β-lactamases, and (iv) P. aeruginosa isolates with metallo-β-lactamases were tested by the agar dilution method of the National Committee for Clinical Laboratory Standards. Selection of resistant P. aeruginosa mutants was investigated in single- and multistep procedures. Doripenem MICs for isolates without acquired resistance mostly were 0.12 to 0.5 μg/ml, whereas meropenem MICs were 0.25 to 0.5 μg/ml and imipenem MICs were 1 to 2 μg/ml. The MICs of doripenem, meropenem, ertapenem, and noncarbapenems for isolates with increased efflux-type resistance were elevated, whereas the MICs of imipenem were less affected. The MICs of doripenem were increased by the loss of OprD but not by derepression of AmpC; nevertheless, and as with other carbapenems, the impermeability-determined resistance caused by the loss of OprD corequired AmpC activity and was lost in OprD− mutants also lacking AmpC. The TEM, PSE, PER, and OXA enzymes did not significantly protect P. aeruginosa PU21 against the activity of doripenem, whereas MICs of ≥16 μg/ml were seen for clinical isolates with VIM and IMP metallo-β-lactamases. Resistant mutants seemed to be harder to select with doripenem than with other carbapenems (or noncarbapenems), and the fold increases in the MICs were smaller for the resistant mutants. Single-step doripenem mutants were mostly resistant only to carbapenems and had lost OprD; multistep mutants had broader resistance, implying the presence of additional mechanisms, putatively including up-regulated efflux. Most mutants selected with aminoglycosides and quinolones had little or no cross-resistance to carbapenems, including doripenem.

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 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 Fluconazole Susceptibilities of Bloodstream Candidasp. Isolates as Determined by National Committee for Clinical Laboratory Standards Method M27-A and Two Other Methods

1999 ◽  
Vol 37 (7) ◽  
pp. 2197-2200 ◽  
Author(s):  
Emilia Cantón ◽  
Javier Pemán ◽  
Alfonso Carrillo-Muñoz ◽  
Ana Orero ◽  
Pedro Ubeda ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Geometric Mean ◽  
Inhibition Zone ◽  
Diffusion Method ◽  
National Committee ◽  
Dilution Method ◽  
Inhibition Zone Diameter ◽  
Zone Diameter ◽  
The Mean

The in vitro activity of fluconazole against 143Candida spp. obtained from the bloodstreams of 143 hospitalized patients from 1995 to 1997 was studied. Susceptibility tests were carried out by two macrodilution methods, the M27-A and a modified M27-A method (0.165 M, pH 7/morpholinepropanesulfonic acid-buffered RPMI 1640 medium supplemented with 20 g ofd-dextrose per liter), and by the agar diffusion method (with 15-μg fluconazole [Neo-Sensitab] tablets). With 2 μg of fluconazole per ml, 96.92% of 65 C. albicans isolates, 86.2% of 58 C. parapsilosis isolates 7 of 8 C. tropicalis isolates, and 1 of 6 C. glabrata isolates were inhibited. Only one strain of C. albicans and one strain of C. tropicalis were resistant. The agreement between the two macrodilution methods was greater than 90% within ±2 log2 dilutions for all strains except C. glabrata (83.3%) and C. tropicalis(87.5%). Generally, MICs were 1 log2 dilution lower in glucose-supplemented RPMI 1640 medium. No correlation between zone sizes and MICs was found. All strains susceptible by the diffusion test were susceptible by the dilution method, but the converse was not necessarily true. Interestingly, inhibition zones were smaller forC. albicans, for which the geometric mean MIC was 0.29 μg/ml and the mean inhibition zone diameter was 25.7 mm, while for C. parapsilosis the geometric mean MIC was 0.96 μg/ml and the mean inhibition zone diameter was 31.52 mm. In conclusion, the two macrodilution methods give similar results. The modified M27-A method with 2% dextrose has the advantage of shortening the incubation time and simplifying the endpoint determination.

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 Antibiotic resistance pattern of Bacteroides fragilis isolated from clinical and colorectal specimens

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Seyedesomaye Jasemi ◽  
Mohammad Emaneini ◽  
Zahra Ahmadinejad ◽  
Mohammad Sadegh Fazeli ◽  
Leonardo A. Sechi ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Active Agent ◽  
Bacteroides Fragilis ◽  
Penicillin G ◽  
Clinical Samples ◽  
Resistance Pattern ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Antibiotic Resistance Pattern

Abstract Background Bacteroides fragilis is a part of the normal gastrointestinal flora, but it is also the most common anaerobic bacteria causing the infection. It is highly resistant to antibiotics and contains abundant antibiotic resistance mechanisms. Methods The antibiotic resistance pattern of 78 isolates of B. fragilis (22 strains from clinical samples and 56 strains from the colorectal tissue) was investigated using agar dilution method. The gene encoding Bacteroides fargilis toxin bft, and antibiotic resistance genes were targeted by PCR assay. Results The highest rate of resistance was observed for penicillin G (100%) followed by tetracycline (74.4%), clindamycin (41%) and cefoxitin (38.5%). Only a single isolate showed resistance to imipenem which contained cfiA and IS1186 genes. All isolates were susceptible to metronidazole. Accordingly, tetQ (87.2%), cepA (73.1%) and ermF (64.1%) were the most abundant antibiotic-resistant genes identified in this study. MIC values for penicillin, cefoxitin and clindamycin were significantly different among isolates with the cepA, cfxA and ermF in compare with those lacking such genes. In addition, 22.7 and 17.8% of clinical and GIT isolates had the bft gene, respectively. Conclusions The finding of this study shows that metronidazole is highly in vitro active agent against all of B. fragilis isolates and remain the first-line antimicrobial for empirical therapy.

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 Comparative In Vitro Activities of Amoxicillin-Clavulanate against Aerobic and Anaerobic Bacteria Isolated from Antral Puncture Specimens from Patients with Sinusitis

1999 ◽  
Vol 43 (3) ◽  
pp. 705-707 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
C. Vreni Merriam
Keyword(s):  
Haemophilus Influenzae ◽  
Anaerobic Bacteria ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Antimicrobial Susceptibilities ◽  
Amoxicillin Clavulanate ◽  
Agar Dilution ◽  
Peptostreptococcus Magnus ◽  
Aerobic And Anaerobic

By an agar dilution method, the antimicrobial susceptibilities of antral sinus puncture isolates were studied. Pneumococci were generally susceptible to amoxicillin, azithromycin, and clarithromycin, but 17% of pneumococcal isolates were resistant to cefuroxime.Haemophilus influenzae isolates were resistant to amoxicillin and clarithromycin. β-Lactamase production occurred in 69% of Prevotella species. One-third ofPeptostreptococcus magnus isolates were resistant to azithromycin and clarithromycin. Cefuroxime had limited activity against Prevotella species and P. magnus. Levofloxacin was active against most isolates except peptostreptococci. Amoxicillin-clavulanate was active against all isolates, with the MIC at which 90% of the isolates were inhibited being ≤1 μg/ml.

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