scholarly journals gyrA Mutations Associated with Quinolone Resistance in Bacteroides fragilis Group Strains

2001 ◽  
Vol 45 (7) ◽  
pp. 1977-1981 ◽  
Author(s):  
Herin Oh ◽  
Nagwa El Amin ◽  
Todd Davies ◽  
Peter C. Appelbaum ◽  
Charlotta Edlund
Keyword(s):  
Amino Acid ◽  
Anaerobic Bacteria ◽  
Bacteroides Fragilis ◽  
Quinolone Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Amino Acid Residues ◽  
Bacteroides Fragilis Group ◽  
Agar Dilution

ABSTRACT Mutations in the gyrA gene contribute considerably to quinolone resistance in Escherichia coli. Mechanisms for quinolone resistance in anaerobic bacteria are less well studied. TheBacteroides fragilis group are the anaerobic organisms most frequently isolated from patients with bacteremia and intraabdominal infections. Forty-four clinafloxacin-resistant and-susceptible fecal and clinical isolates of the B. fragilis group (eightBacteroides fragilis, three Bacteroides ovatus, five Bacteroides thetaiotaomicron, six Bacteroides uniformis, and 22 Bacteroides vulgatus) and six ATCC strains of the B. fragilis group were analyzed as follows: (i) determination of susceptibility to ciprofloxacin, levofloxacin, moxifloxacin, and clinafloxacin by the agar dilution method and (ii) sequencing of the gyrA quinolone resistance-determining region (QRDR) located between amino acid residues equivalent to Ala-67 through Gln-106 in E. coli. Amino acid substitutions were found at hotspots at positions 82 (n = 15) and 86 (n = 8). Strains with Ser82Leu substitutions (n = 13) were highly resistant to all quinolones tested. Mutations in other positions of gyrA were also frequently found in quinolone-resistant and -susceptible isolates. Eight clinical strains that lacked mutations in their QRDR were susceptible to at least two of the quinolones tested. Although newer quinolones have good antimicrobial activity against the B. fragilis group, quinolone resistance in B. fragilisstrains can be readily selected in vivo. Mutational events in the QRDR of gyrA seem to contribute to quinolone resistance inBacteroides species.

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 Comparison of the Antimicrobial Susceptibility Results of Bacteroides fragilis Group Isolates Determined by Agar Dilution and the Tentative EUCAST Disk Diffusion Method

2021 ◽  
Author(s):  
Semra Eminoğlu ◽  
Bermal Tekeş ◽  
Elvan Sayın ◽  
Nurver Ülger Toprak
Keyword(s):  
Antimicrobial Susceptibility ◽  
Bacteroides Fragilis ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disc Diffusion ◽  
Disc Diffusion Method ◽  
Bacteroides Fragilis Group ◽  
Agar Dilution

Objective: In this study it was aimed to determine the antimicrobial susceptibility of Bacteroides fragilis group (BFG) bacteria using recently developed European Committee on Antimicrobial Susceptibility Testing (EUCAST) disc diffusion method and agar dilution method recommended by Clinical Laboratory Standart Institude (CLSI) for anaerobes and to investigate the agreement of the results of two tests. Method: The antimicrobial susceptibilities of a total of 56 BFG strains isolated from clinical samples and identified by MALDI-TOF MS analysis between January 2017 and December 2018, were tested to ampicillin, ampicillin/sulbactam, cefoxitin, imipenem, clindamycin, tigecycline, moxifloxacin and metronidazole MICs were determined by agar dilution method using sheep blood supplemented Brucella agar and disk diffusion test using host blood supplemented Fastidius Anaerobic Agar (FAA). Results: Six different BFG species consisting mostly strains of Bacteroides fragilis (n=34, 61%) and Bacteroides thetaiotaomicron (n=11, 20%) isolated from various clinical samples such as intraabdominal abscess (n= 24), blood (n=10) and tissue biopsy samples (n=11).were identified. Imipenem and metronidazole were the most effective antimicrobials with 98.2% susceptibility rates, followed by tigecycline, ampicillin/sulbactam, moxifloxacin and clindamycin with susceptibility rates of 89.3%, 66.1%, 57.1% and 46.4%, respectively. Most concordant results were obtained with metronidazole (100%), imipenem (89.8%) and tigecycline (89.8%). Acceptable compliance rates were not found for other antimicrobials. Conclusion: We can say that disc diffusion method is a fast, easy-to-apply, and reliable method used in clinical microbiology laboratories to determine the susceptibility of BFG bacteria to metronidazole, imipenem and tigecycline. However, to evolve a standard method especially for other antimicrobials, the experimental conditions should be optimized with studies dome with greater number of isolates.

scholarly journals Meningococcal Quinolone Resistance Originated from Several Commensal Neisseria Species

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
Mingliang Chen ◽  
Chi Zhang ◽  
Xi Zhang ◽  
Min Chen
Keyword(s):  
Acquired Resistance ◽  
Quinolone Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Illumina Platform ◽  
Content Type ◽  
Neisseria Species ◽  
Agar Dilution ◽  
Recombinant Fragments ◽  
Commensal Neisseria

ABSTRACT Quinolone resistance is increasing in Neisseria meningitidis, with its prevalence in China being high (>70%), but its origin remains unknown. The aim of this study was to investigate the donors of mutation-harboring gyrA alleles in N. meningitidis. A total of 198 N. meningitidis isolates and 293 commensal Neisseria isolates were collected between 2005 and 2018 in Shanghai, China. The MICs of ciprofloxacin were determined using the agar dilution method. The resistance-associated genes gyrA and parC were sequenced for all isolates, while a few isolates were sequenced on the Illumina platform. The prevalences of quinolone resistance in the N. meningitidis and commensal Neisseria isolates were 67.7% (134/198) and 99.3% (291/293), respectively. All 134 quinolone-resistant N. meningitidis isolates possessed mutations in T91 (n = 123) and/or D95 (n = 12) of GyrA, with 7 isolates also harboring ParC mutations and exhibiting higher MICs. Phylogenetic analysis of the gyrA sequence identified six clusters. Among the 71 mutation-harboring gyrA alleles found in 221 N. meningitidis isolates and genomes (n = 221), 12 alleles (n = 103, 46.6%) were included in the N. meningitidis cluster, while 20 alleles (n = 56) were included in the N. lactamica cluster, 27 alleles (n = 49) were included in the N. cinerea cluster, and 9 alleles (n = 10) were included in the N. subflava cluster. Genomic analyses identified the exact N. lactamica donors of seven mutation-harboring gyrA alleles (gyrA92, gyrA97, gyrA98, gyrA114, gyrA116, gyrA151, and gyrA230) and the N. subflava donor isolate of gyrA171, with the sizes of the recombinant fragments ranging from 634 to 7,499 bp. Transformation of gyrA fragments from these donor strains into a meningococcal isolate increased its ciprofloxacin MIC from 0.004 μg/ml to 0.125 or 0.19 μg/ml and to 0.5 μg/ml with further transformation of an additional ParC mutation. Over half of the quinolone-resistant N. meningitidis isolates acquired resistance by horizontal gene transfer from three commensal Neisseria species. Quinolone resistance in N. meningitidis increases in a stepwise manner.

An improved susceptibility test based on Amberlite reveals the potential antilisterial activity of fosfomycin in vitro

2013 ◽  
Vol 59 (4) ◽  
pp. 252-259 ◽  
Author(s):  
Lei Han ◽  
Jin'e Lei ◽  
Shaoshan Han ◽  
Li He ◽  
Chaofeng Ma ◽  
...  
Keyword(s):  
Brain Heart Infusion ◽  
Susceptibility Test ◽  
Host Cells ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution

Listeria monocytogenes is resistant to fosfomycin in vitro but is susceptible in vivo due to increased expression of positive regulator factor A (PrfA) and its dependent factor, hexose phosphate transporter (Hpt), upon infection of host cells. Amberlite, a polymeric adsorbent resin, could induce PrfA-dependent gene expression and thus, in theory, improve the sensitivity of L. monocytogenes to fosfomycin in vitro. In the current study, an improved susceptibility test based on Amberlite was developed using reference strains. Thirty-five clinical isolates were further examined to verify those preliminary results. Briefly, Amberlite increased in vitro fosfomycin sensitivity of all strains. Optimal Amberlite concentrations, as evaluated through the expression of phospholipase B (PlcB) and Hpt, were 10% and 15% (w/v) in agar media and 3% (w/v) in broth media. Mueller–Hinton (MH) medium, tryptone soya (TS) medium, and brain heart infusion (BHI) medium were used to verify the results in the control strains using agar dilution and broth micro- and macro-dilution methods. Better listerial growth was shown in TS and BHI than in MH. Both broth dilution methods yielded lower minimal inhibitory concentration (MIC) of fosfomycin than the agar dilution method. The MIC of fosfomycin for 35 clinical isolates was 2–32 μg/mL, suggesting improved susceptibility. In conclusion, in vitro sensitivity of L. monocytogenes to fosfomycin was substantially improved in the presence of 3% Amberlite-supplemented TSB or BHIB and the broth microdilution method. This improved method revealed the potential antilisterial activity of fosfomycin in vitro and could facilitate the therapy of listeriosis using fosfomycin.

scholarly journals In Vitro Activity of Moxifloxacin against 923 Anaerobes Isolated from Human Intra-Abdominal Infections

2006 ◽  
Vol 50 (1) ◽  
pp. 148-155 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
C. Vreni Merriam ◽  
...  
Keyword(s):  
Bacteroides Fragilis ◽  
Vitro Activity ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Species Variation ◽  
In Vitro Activity ◽  
Resistant Species ◽  
Agar Dilution ◽  
Abdominal Infections

ABSTRACT The in vitro activity of moxifloxacin against 923 recent anaerobic isolates obtained from pretreatment cultures in patients with complicated intra-abdominal infections was studied using the CLSI M11-A-6 agar dilution method. Moxifloxacin was active against 87% (96 of 110) Bacteroides fragilis strains at ≤1 μg/ml and 87% (79 of 90) B. thetaiotaomicron strains at ≤2 μg/ml. Species variation was seen, with B. uniformis, B. vulgatus, Clostridium clostridioforme, and C. symbiosum being least susceptible and accounting for most of the resistant isolates; excluding the aforementioned four resistant species, 86% (303 of 363) of Bacteroides species isolates and 94% (417 of 450) of all other genera and species were susceptible to ≤2 μg/ml of moxifloxacin. Overall, moxifloxacin was active against 763 of 923 (83%) of strains at ≤2 μg/ml, supporting its use as a monotherapy for some community-acquired intra-abdominal infections.

scholarly journals In Vitro Activities of Ramoplanin, Teicoplanin, Vancomycin, Linezolid, Bacitracin, and Four Other Antimicrobials against Intestinal Anaerobic Bacteria

2003 ◽  
Vol 47 (7) ◽  
pp. 2334-2338 ◽  
Author(s):  
D. M. Citron ◽  
C. V. Merriam ◽  
K. L. Tyrrell ◽  
Y. A. Warren ◽  
H. Fernandez ◽  
...  
Keyword(s):  
Anaerobic Bacteria ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gram Positive ◽  
Gram Negative ◽  
Excellent Activity ◽  
Agar Dilution ◽  
Resistant Strains ◽  
Fusobacterium Varium

ABSTRACT By using an agar dilution method, the in vitro activities of ramoplanin, teicoplanin, vancomycin, linezolid, and five other agents were determined against 300 gram-positive and 54 gram-negative strains of intestinal anaerobes. Ramoplanin was active at ≤2 μg/ml against 287 of 300 (95.7%) gram-positive organisms, including 18 strains of Clostridium difficile for which MICs of ramoplanin were 0.25 to 0.5 μg/ml; for 3 of these, linezolid MICs were 8 to 16 μg/ml. Nineteen Clostridium innocuum strains for which the vancomycin MIC at which 90% of strains were inhibited was 16 μg/ml were susceptible to ramoplanin at 0.06 to 0.25 μg/ml and to teicoplanin at 0.125 to 1.0 μg/ml. All strains of Eubacterium, Actinomyces, Propionibacterium, and Peptostreptococcus spp. were inhibited by ≤0.25 μg of ramoplanin per ml and ≤1 μg of vancomycin per ml. Ramoplanin was also active at ≤4 μg/ml against 15 of 22 of the Prevotella and Porphyromonas strains tested, but ramoplanin MICs for all 31 strains of the Bacteroides fragilis group, the Fusobacterium mortiferum-Fusobacterium varium group, and Veillonella spp. were ≥256 μg/ml. Ramoplanin displays excellent activity against C. difficile and other gram-positive enteric anaerobes, including vancomycin-resistant strains; however, it has poor activity against most gram-negative anaerobes and thus potentially has a lesser effect on the ecological balance of normal fecal flora.

scholarly journals Cefotetan Susceptibility Testing Against Anaerobic Bacteria From Obstetrical and Gynecologic Sources: Comparison of Five Different Methods

1993 ◽  
Vol 1 (1) ◽  
pp. 23-26
Author(s):  
Maurizio Maccato ◽  
Gerald Riddle ◽  
Sebastian Faro
Keyword(s):  
Susceptibility Testing ◽  
Anaerobic Bacteria ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gradient System ◽  
Minimal Inhibitory Concentrations ◽  
Gradient Technique ◽  
Doubling Dilution ◽  
Agar Dilution ◽  
Elution Method

Five different antibiotic susceptibility methods were utilized to test the effectiveness of cefotetan against 200 anaerobic bacteria recovered from patients with obstetrical or gynecological infections. The object of this study was to determine if a more economical and rapid method for anaerobic susceptibility testing was as acceptable as the reference agar dilution method. The five methods were: 1) broth disk elution, 2) microbroth technique, 3) a commercially available microbroth technique, 4) a commercially available spiral gradient technique, and 5) reference agar dilution. The minimal inhibitory concentrations (MICs) calculated from the spiral gradient technique were equal to or within one doubling dilution of the reference system in 99.5% of cases, while the percentage for the commercially available microbroth system was 96.8%, very similar to the microbroth technique used in our laboratory that yielded a percentage of 96.3. The disk elution method correlated to the reference agar dilution method in 95.3% cases. While the overall agreement between these techniques is good, especially for the spiral gradient system, clustering of certain organisms near the breakpoint of the antibiotic tested results in variability in the labeling of these organisms as susceptible or resistant. This problem appears to be particularly significant for the disk elution method. Therefore, further refinements in these methods of suscleptibility testing are needed in order to provide a more clinically useful assessment of the susceptibility or resistance of certain bacterial isolates.

scholarly journals Comparative In Vitro Activities of Ertapenem (MK-0826) against 1,001 Anaerobes Isolated from Human Intra-Abdominal Infections

2000 ◽  
Vol 44 (9) ◽  
pp. 2389-2394 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
C. Vreni Merriam ◽  
Yumi Warren ◽  
Kerin L. Tyrrell
Keyword(s):  
Geographical Variation ◽  
Bacteroides Fragilis ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution ◽  
Abdominal Infections ◽  
Group Species

ABSTRACT By using an agar dilution method, the comparative in vitro activities of ertapenem (MK-0826) were studied against 1,001 anaerobes isolated from human intra-abdominal infections in 17 countries worldwide. MK-0826 was uniformly active against all isolates, including all Bacteroides fragilis group species isolates, with the exception of 12 of 61 (20%) strains of Bilophila wadsworthia, 3 strains of lactobacilli, and 1 isolate ofAcidaminococcus fermentans. Geographical variation in activity was not observed.

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