scholarly journals In Vitro Activities of 15 Antimicrobial Agents against 110 Toxigenic Clostridium difficile Clinical Isolates Collected from 1983 to 2004

2007 ◽  
Vol 51 (8) ◽  
pp. 2716-2719 ◽  
Author(s):  
David W. Hecht ◽  
Minerva A. Galang ◽  
Susan P. Sambol ◽  
James R. Osmolski ◽  
Stuart Johnson ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Antimicrobial Agents ◽  
Treatment Strategies ◽  
The United States ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
In Vitro Susceptibility ◽  
Agar Dilution

ABSTRACT The incidence and severity of Clostridium difficile-associated disease (CDAD) is increasing, and standard treatment is not always effective. Therefore, more-effective antimicrobial agents and treatment strategies are needed. We used the agar dilution method to determine the in vitro susceptibility of the following antimicrobials against 110 toxigenic clinical isolates of C. difficile from 1983 to 2004, primarily from the United States: doripenem, meropenem, gatifloxacin, levofloxacin, moxifloxacin, OPT-80, ramoplanin, rifalazil, rifaximin, nitazoxanide, tizoxanide, tigecycline, vancomycin, tinidazole, and metronidazole. Included among the isolates tested were six strains of the toxinotype III, NAP1/BI/027 group implicated in recent U.S., Canadian, and European outbreaks. The most active agents in vitro were rifaximin, rifalazil, tizoxanide, nitazoxanide, and OPT-80 with MICs at which 50% of the isolates are inhibited (MIC50) and MIC90 values of 0.0075 and 0.015 μg/ml, 0.0075 and 0.03 μg/ml, 0.06 and 0.125 μg/ml, 0.06 and 0.125 μg/ml, 0.125 and 0.125 μg/ml, respectively. However, for three isolates the rifalazil and rifaximin MICs were very high (MIC of >256 μg/ml). Ramoplanin, vancomycin, doripenem, and meropenem were also very active in vitro with narrow MIC50 and MIC90 ranges. None of the isolates were resistant to metronidazole, the only agent for which there are breakpoints, with tinidazole showing nearly identical results. These in vitro susceptibility results are encouraging and support continued evaluation of selected antimicrobials in clinical trials of treatment for CDAD.

scholarly journals 1593. Antimicrobial Activity of Ceftazidime-Avibactam and Comparator Agents Against OXA-48 β-lactamase–Producing Enterobacterales Collected in International Medical Centers, Including the United States, in 2017–2018

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S793-S793
Author(s):  
Lynn-Yao Lin ◽  
Dmitri Debabov ◽  
William Chang
Keyword(s):  
Antimicrobial Agents ◽  
The United States ◽  
Resistance Mechanisms ◽  
Clinical Isolates ◽  
Surveillance Program ◽  
Multiple Resistance ◽  
In Vitro Susceptibility ◽  
Medical Centers ◽  
Custom Made

Abstract Background OXA-48 is a carbapenemase with low-level hydrolytic activity toward cephalosporins. This study evaluated in vitro activities of ceftazidime-avibactam (CAZ-AVI), meropenem (MEM), meropenem-vaborbactam (MVB), ceftolozane-tazobactam (C/T), and other antimicrobial agents against 113 OXA-48-producing Enterobacterales with multiple resistance mechanisms collected in a 2017–2018 global surveillance program. Methods Nonduplicate clinical isolates of 113 Enterobacterales were collected from medical centers in 25 countries in 2017–2018. In vitro susceptibility tests were performed by broth microdilution with a custom-made panel consisting of CAZ-AVI, ceftazidime (CAZ), MEM, MVB, C/T, colistin (COL), gentamicin (GEN), levofloxacin (LEV), and amikacin (AMK). Whole genome sequencing or quantitative PCR data were used to analyze resistance mechanisms, such as OXA-48, extended-spectrum β-lactamase (ESBL), original-spectrum β-lactamase (OSBL), and AmpC β-lactamase. Clinical and Laboratory Standards Institute breakpoints were applied for susceptibility interpretations. Results Of 113 OXA-48–producing clinical isolates, 20 carried OXA-48 alone. The remaining 93 isolates carried additional β-lactamases, including 63 with ESBL (CTX-M-15) + OSBL (SHV, TEM), 15 with AmpC (DHA, AAC, CMY) + ESBL (CTX-M-15), and 15 with OSBL (SHV, TEM). 99.1% (all but 1) of all isolates tested were susceptible to CAZ-AVI, whereas 71.7%, 17.7%, and 14.2% were susceptible to MVB, MEM, and C/T, respectively. Among isolates harboring multiple resistance mechanisms (OXA-48 + ESBL + OSBL; n=63), 98.4%, 69.8%, 11.1%, and 7.9% were susceptible to CAZ-AVI, MVB, MEM, and C/T, respectively. Among isolates carrying OXA-48 + AmpC + ESBL + OSBL (n=15), 100%, 66.7%, 13.3%, and 13.3% were susceptible to CAZ-AVI, MVB, MEM, and C/T, respectively (Table). Aminoglycosides (AMK and GEN) and other β-lactams (eg, CAZ) were 20%–90% active against these isolates. COL was the second most effective comparator, inhibiting 83.2% of these isolates. Table Conclusion CAZ-AVI was the most effective agent in this study compared with other antibiotics, including β-lactams, β-lactam–β-lactamase inhibitor combinations, aminoglycosides, and COL, against OXA-48-producing Enterobacterales carrying multiple β-lactamases. Disclosures Lynn-Yao Lin, MS, AbbVie (Employee) Dmitri Debabov, PhD, AbbVie (Employee) William Chang, BS, AbbVie (Employee)

scholarly journals In vitro susceptibility studies and detection of vancomycin resistance genes in clinical isolates of enterococci in Nagasaki, Japan

1997 ◽  
Vol 119 (2) ◽  
pp. 175-181 ◽  
Author(s):  
Y. HIRAKATA ◽  
T. YAMAGUCHI ◽  
K. IZUMIKAWA ◽  
J. MATSUDA ◽  
K. TOMONO ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Antimicrobial Agents ◽  
The United States ◽  
Vancomycin Resistance ◽  
Single Step ◽  
Clinical Isolates ◽  
Glycopeptide Resistance ◽  
In Vitro Susceptibility ◽  
Enterococcus Gallinarum

Glycopeptide resistance in enterococci is now a cause of clinical concern in the United States and Europe. However, details of vancomycin resistance in enterococci in Japan have been unknown. We measured minimum inhibitory concentrations (MICs) of various antimicrobial agents for a total of 218 clinical strains of enterococci isolated in our hospital in 1995–6 in addition to 15 strains with known genotypic markers of resistance. We also screened vancomycin resistance genes using a single step multiplex-PCR.In clinical isolates, only two strains of Enterococcus gallinarum were of intermediate resistance to vancomycin (MIC, 8 μg/ml), while the others were all susceptible. Glycopeptides (vancomycin and teicoplanin) and streptogramins (RP 58500 and RPR 106972) showed potent antimicrobial effects for the isolates. In addition, ampicillin was also potent for Enterococcus faecalis, while ampicillin, minocycline and gentamicin were potent for Enterococcus avium. No vanA or vanB genes were detected, while vanC1 and vanC23 genes were detected from two and four strains, respectively. Our results suggest that incidence of VRE in Japan may be estimated as still very low at this time.

scholarly journals Increasing antibiotic resistance in clinical isolates of Aeromonas strains in Taiwan.

1996 ◽  
Vol 40 (5) ◽  
pp. 1260-1262 ◽  
Author(s):  
W C Ko ◽  
K W Yu ◽  
C Y Liu ◽  
C T Huang ◽  
H S Leu ◽  
...  
Keyword(s):  
United States ◽  
Antibiotic Resistance ◽  
The United States ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Extended Spectrum ◽  
Agar Dilution

A total of 234 clinical isolates of Aeromonas, primarily A. hydrophila, were collected for the present study. Most were isolates from blood. By the agar dilution method, more than 90% of the Aeromonas strains were found to be susceptible to moxalactam, ceftazidime, cefepime, aztreonam, imipenem, amikacin, and fluoroquinolones, but they were more resistant to tetracycline, trimethoprim-sulfamethoxazole, some extended-spectrum cephalosporins, and aminoglycosides than strains from the United States and Australia.

scholarly journals In Vitro Activities of Garenoxacin (BMS-284756) against 170 Clinical Isolates of Nine Pasteurella Species

2002 ◽  
Vol 46 (9) ◽  
pp. 3068-3070 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
C. Vreni Merriam ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
...  
Keyword(s):  
Pasteurella Multocida ◽  
Active Agent ◽  
Culture Collection ◽  
Clinical Isolates ◽  
American Type Culture Collection ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution

ABSTRACT The in vitro susceptibilities of 170 clinical isolates plus 12 American Type Culture Collection strains of Pasteurella species comprising nine species and three Pasteurella multocida subspecies were studied by an agar dilution method. Garenoxacin (BMS-284756), a new des-fluoro(6) quinolone, was active at ≤0.06 μg/ml against all isolates, including four β-lactamase-producing strains, with >90% of the strains susceptible to ≤0.008 μg/ml. Garenoxacin was generally 1 to 2 dilutions more active than levofloxacin and moxifloxacin and was the most active agent tested. Cefoxitin required 1 μg/ml for inhibition of 51 of 182 (29%) of strains, and 3 strains (also β-lactamase producers) were resistant to doxycycline.

In vitro synergy testing of macrolide-quinolone combinations against 41 clinical isolates of Legionella.

1996 ◽  
Vol 40 (6) ◽  
pp. 1419-1421 ◽  
Author(s):  
S J Martin ◽  
S L Pendland ◽  
C Chen ◽  
P Schreckenberger ◽  
L H Danziger
Keyword(s):  
Yeast Extract ◽  
Antimicrobial Therapy ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution ◽  
Legionella Species ◽  
Checkerboard Assay ◽  
Synergy Testing

Combination antimicrobial therapy against Legionella species has not been well studied. Several quinolones have activity against Legionella strains, which prompted this in vitro search for a synergistic combination with the macrolides. By a checkerboard assay, erythromycin, clarithromycin, and azithromycin, each in combination with ciprofloxacin and levofloxacin, were tested for synergy against 46 isolates of Legionella. The agar dilution method was employed using buffered charcoal-yeast extract media. A final inoculum of 10(4) CFU per spot was prepared from 24-h growth of each isolate. Plates were incubated at 35 degrees C for 48 h. Synergy, partial synergy, additive effect, or indifference was observed for all combinations of antibiotics tested. There was no antagonism observed. Synergy occurred to a significantly greater extent for the clarithromycin-levofloxacin (P = 0.0001) and azithromycin-levofloxacin (P = 0.003) combinations versus erythromycin-levofloxacin. The azithromycin-ciprofloxacin combination demonstrated significantly greater synergy than did either erythromycin-ciprofloxacin (P = 0.003) or clarithromycin-ciprofloxacin (P = 0.001). The newer macrolides clarithromycin and azithromycin may be more active in combination with a fluoroquinolone than is erythromycin.

scholarly journals Telithromycin- and Fluoroquinolone-Resistant Streptococcus pneumoniae in Taiwan with High Prevalence of Resistance to Macrolides and β-Lactams: SMART Program 2001 Data

2003 ◽  
Vol 47 (7) ◽  
pp. 2145-2151 ◽  
Author(s):  
Po-Ren Hsueh ◽  
Lee-Jene Teng ◽  
Tsu-Lan Wu ◽  
Dine Yang ◽  
Wen-Kuei Huang ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Random Amplified Polymorphic Dna ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Time Period ◽  
High Prevalence ◽  
Agar Dilution ◽  
Different Parts

ABSTRACT There is a high prevalence of β-lactam- and macrolide-resistant Streptococcus pneumoniae in Taiwan. To understand the in vitro susceptibilities of recent isolates of S. pneumoniae to fluoroquinolones and telithromycin (which is not available in Taiwan), the MICs of 23 antimicrobial agents for 936 clinical isolates of S. pneumoniae isolated from different parts of Taiwan from 2000 to 2001 were determined by the agar dilution method. Overall, 72% of isolates were not susceptible to penicillin (with 61% being intermediate and 11% being resistant) and 92% were resistant to erythromycin. Telithromycin MICs were ≥1 μg/ml for 16% of the isolates, and for 99% of these isolates the MICs of all macrolides tested were ≥256 μg/ml; all of these isolates had the constitutive macrolide-lincosamide-streptogramin B phenotype. Eighty-eight percent of the isolates were resistant to three or more classes of drugs. The ciprofloxacin MICs were ≥4 μg/ml for six (0.6%) isolates from five patients collected in 2000 and 2001, and the levofloxacin MICs were ≥8 μg/ml for five of these isolates. Seven isolates for which ciprofloxacin MICs were ≥4 μg/ml, including one isolate recovered in 1999, belonged to three serotypes (serotype 19F, five isolates; serotype 23A, one isolate; and serotype 23B, one isolate). The isolates from the six patients for which ciprofloxacin MICs were ≥4 μg/ml had different pulsed-field gel electrophoresis profiles and random amplified polymorphic DNA patterns, indicating that no clonal dissemination occurred over this time period. Despite the increased rate of fluoroquinolone use, the proportion of pneumococcal isolates for which ciprofloxacin MICs were elevated (≥4 μg/ml) remained low. However, the occurrence of telithromycin resistance is impressive and raises concerns for the future.

scholarly journals In Vitro Activities of Garenoxacin (BMS 284756) against 108 Clinical Isolates of Gardnerella vaginalis

2002 ◽  
Vol 46 (12) ◽  
pp. 3995-3996 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
C. Vreni Merriam ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
...  
Keyword(s):  
Clinical Isolates ◽  
Gardnerella Vaginalis ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution

ABSTRACT Garenoxacin (BMS 284756) was active against 105 of 108 (97%) recent clinical Gardnerella vaginalis isolates at ≤2 μg/ml by using the reference agar dilution method for anaerobes. Twenty-eight percent of isolates (31 of 108) were resistant to metronidazole, and 44% were resistant to doxycycline. All were susceptible to clindamycin and ampicillin-sulbactam.

scholarly journals In Vitro Activities of a New Des-Fluoro(6) Quinolone, Garenoxacin, against Clinical Anaerobic Bacteria

2003 ◽  
Vol 47 (11) ◽  
pp. 3667-3671 ◽  
Author(s):  
A. Liebetrau ◽  
A. C. Rodloff ◽  
J. Behra-Miellet ◽  
L. Dubreuil
Keyword(s):  
Clostridium Difficile ◽  
Anaerobic Bacteria ◽  
Bacteroides Fragilis ◽  
Antimicrobial Activities ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gram Positive ◽  
Agar Dilution ◽  
Gram Positive Cocci

ABSTRACT The antimicrobial activities of garenoxacin and eight other antibiotics against 641 anaerobic isolates were evaluated with the NCCLS agar dilution method. Overall, the MICs of garenoxacin for 50 and 90% of the strains tested (in micrograms per milliliter) were as follows: Bacteroides fragilis group, 0.5 and 2; Prevotella spp., 0.25 and 2; Fusobacterium spp., 0.25 and 0.5; Porphyromonas spp., 0.125 and 0.25; Bilophila wadsworthia, 0.5 and 1; Veillonella spp., 0.25 and 0.5; Clostridium spp., 0.25 and 1; Clostridium difficile, 2 and >64; Bifidobacterium spp., 1 and 2; Eggerthella lenta, 0.25 and 1; Propionibacterium spp., 0.5 and 0.5; gram-positive cocci, 0.125 and 0.25.

scholarly journals In Vitro Antimicrobial Susceptibility Testing of Helicobacter felis, H. bizzozeronii, and H. salomonis

2005 ◽  
Vol 49 (7) ◽  
pp. 2997-3000 ◽  
Author(s):  
K. Van den Bulck ◽  
A. Decostere ◽  
I. Gruntar ◽  
M. Baele ◽  
B. Krt ◽  
...  
Keyword(s):  
Antimicrobial Agent ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Acquired Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Helicobacter Felis ◽  
Agar Dilution

ABSTRACT The susceptibilities of Helicobacter felis (15 strains), H. bizzozeronii (7 strains), and H. salomonis (3 strains) to 10 antimicrobial agents were investigated by determination of the MIC using the agar dilution method. No consistent differences were noticed between the different Helicobacter species, which were all highly susceptible to ampicillin, clarithromycin, tetracycline, tylosin, enrofloxacin, gentamicin, and neomycin, as demonstrated by low MICs. Higher MICs were obtained for lincomycin (up to 8 μg/ml) and spectinomycin (up to 4 μg/ml). Two H. felis strains showed a MIC of 16 μg/ml for metronidazole, suggesting acquired resistance to this antimicrobial agent.

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