The role of β-lactamase and the permeability barrier on the activity of cephalosporins against members of the Bacteroides fragilis group

1987 ◽  
Vol 33 (3) ◽  
pp. 262-266 ◽  
Author(s):  
François Malouin ◽  
François Lamothe
Keyword(s):  
Clavulanic Acid ◽  
Bacterial Species ◽  
Bacteroides Fragilis ◽  
Permeability Barrier ◽  
Low Permeability ◽  
Minimal Inhibitory Concentrations ◽  
Bacteroides Fragilis Group ◽  
Agar Dilution ◽  
Species Specific

The role of β-lactamase and the permeability barrier on the activity of some β-lactams against 53 strains of the Bacteroides fragilis group was investigated. Minimal inhibitory concentrations of cefamandole, cefoxitin, and cephalothin were determined with or without the addition of clavulanic acid and (or) ethylenediaminetetraacetate using an agar dilution technique. A significant increase of susceptibility with clavulanic acid indicated a role for β-lactamase, and with ethylenediaminetetraacetate, a role for a permeability barrier. We found that both β-lactamase and low permeability decreased the activity of the β-lactams to some extent depending on the bacterial species and the antibiotic. The species-specific exception was B. distasonis which showed only a permeability barrier to all antibiotics tested.

Antianaerobic activity of the ketolide RU 64004 compared to activities of four macrolides, five beta-lactams, clindamycin, and metronidazole.

1997 ◽  
Vol 41 (5) ◽  
pp. 1037-1041 ◽  
Author(s):  
L M Ednie ◽  
S K Spangler ◽  
M R Jacobs ◽  
P C Appelbaum
Keyword(s):  
Clostridium Difficile ◽  
Bacteroides Fragilis ◽  
The Other ◽  
Beta Lactams ◽  
Gram Positive ◽  
Amoxicillin Clavulanate ◽  
Bacteroides Fragilis Group ◽  
Agar Dilution ◽  
Bacteroides Ovatus ◽  
Fusobacterium Varium

Agar dilution methodology (with added Oxyrase in the case of the macrolide group to allow incubation without added CO2) was used to compare the activity of RU 64004, a new ketolide, with the activities of erythromycin, azithromycin, clarithromycin, roxithromycin, clindamycin, amoxicillin with and without clavulanate, piperacillin with and without tazobactam, metronidazole, and imipenem against 379 anaerobes. Overall, RU 64004 yielded an MIC at which 50% of the isolates are inhibited (MIC50) of 1.0 microg/ml and an MIC90 of 16.0 microg/ml. In comparison, MIC50s and MIC90s of erythromycin, azithromycin, clarithromycin, and roxithromycin were 2.0 to 8.0 and >64.0 microg/ml, respectively. MICs of macrolides, including RU 64004, were higher for Bacteroides ovatus, Fusobacterium varium, Fusobacterium mortiferum, and Clostridium difficile than for the other species. RU 64004 was more active against gram-positive rods and cocci, Prevotella and Porphyromonas spp., and fusobacteria other than F. mortiferum and F. varium than against the Bacteroides fragilis group. Overall MIC50s and MIC90s (in micrograms per milliliter), respectively, of other compounds were as follows: clindamycin, 1.0 and 16.0; amoxicillin, 4.0 and 64.0; amoxicillin-clavulanate, 0.5 and 4.0; piperacillin, 8.0 and >64.0; piperacillin-tazobactam, 1.0 and 16.0; metronidazole, 1.0 and 4.0; and imipenem, 0.25 and 1.0.

scholarly journals Susceptibility of clinical isolates of Bacteroides fragilis group strains to cefoxitin, cefoperazone and ticarcillin/clavulanate

2000 ◽  
Vol 42 (3) ◽  
pp. 137-139
Author(s):  
Arnaldo Aires PEIXOTO JÚNIOR ◽  
Márcia Maria de Negreiros P. ROCHA ◽  
José Luciano Bezerra MOREIRA ◽  
Cibele Barreto Mano de CARVALHO
Keyword(s):  
Bacteroides Fragilis ◽  
Reference Method ◽  
Clinical Isolates ◽  
Wound Infections ◽  
Clinical Specimens ◽  
Bacteroides Fragilis Group ◽  
Agar Dilution ◽  
Resistance Rates ◽  
Isolated Species

A total of 40 strains of the B. fragilis group was isolated from clinical specimens in two hospital centers in Fortaleza from 1993 to 1997. The most frequently isolated species was Bacteroides fragilis (19 strains) and most isolates came from intra-abdominal and wound infections. The susceptibility profile was traced for cefoxitin, cefoperazone and ticarcillin-clavulanate by using the agar dilution reference method. All isolates were susceptible to ticarcillin-clavulanate (128/2mug/ml). Resistance rates of 15 and 70% were detected to cefoxitin (64mug/ml) and cefoperazone (64mug/ml), respectively. Such regional results permit a better orientation in choosing this group of antibiotics for prophylaxis and therapy especially in relation to cefoxitin, which is frequently used in the hospital centers studied.

scholarly journals Antimicrobial Susceptibility of Bacteroides fragilis Group Isolates to Clindamycin, Tetracycline and Tigecycline, and Their Possession of tet and ermF Genes, which are Responsible for Resistance

2021 ◽  
Author(s):  
Bermal Tekeş ◽  
Semra Eminoğlu ◽  
Elvam Sayın ◽  
Nurver Ülger Toprak
Keyword(s):  
Resistance Genes ◽  
Bacteroides Fragilis ◽  
Resistance Mechanisms ◽  
Clinical Samples ◽  
Starting Point ◽  
Resistance Transfer ◽  
Bacteroides Fragilis Group ◽  
Agar Dilution ◽  
Resistance Rates ◽  
Sterile Body Fluids

Objective: We aimed to determine the resistance of Bacteroides fragilis group (BFG) bacteria to clindamycin, tetracycline and tigecycline and establish the distribution of related resistance genes. Method: In total 82 BFG strains, isolated from different clinical samples between January 2017 and December 2018, were identified by MALDI-TOF MS. Their antimicrobial sensitivities to were determined using agar dilution methodology (CLSI; M11-A7). The tetM, tetQ, tetX, tetX1, tet36, and ermF genes were investigated by PCR. Results: Eighty-two strains of BFG bacteria, isolated from intra-abdominal abscess (n=36), tissue biopsy (n=16), blood (n=14) and other sterile body fluids (n=12), were identified as Bacteroides fragilis (n=48), Bacteroides thetaiotaomicron (n=17), Bacteroides vulgatus (n=5), Bacteroides ovatus (n=4), Bacteroides caccae (n=1), Bacteroides uniformis (n=1) and Parabacteroides distasonis (n=6). The resistance rates to clindamycin, tetracycline and tigecycline were 54.9%, 84.1%, 4.9%, respectively. Non-B. fragilis isolates were more resistant than B. fragilis strains. In total, 57.3% of the isolates were ermF gene positive, while B. thetaiotaomicron had the highest rate (70.6%). The tet gene positivity ranged from 18.8% to 66.7% among species. The tetQ gene positivity was higher than other tet genes. The 92.7% of the isolates were resistant to at least one antibiotic, while 94% had at least one resistance gene. Conclusion: This study provided data on antimicrobial resistance of our BFG isolates to clindamycin, tetracycline and tigecycline and the related resistance genes. However, our information obtained could also be a starting point for further investigation of the antibiotic resistance mechanisms of Bacteroides species, as well as, resistance transfer among BFG isolates and other bacteria.

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 Detection of non-enterotoxigenic and enterotoxigenic Bacteroides fragilis in stool samples from children in São Paulo, Brazil

2003 ◽  
Vol 45 (4) ◽  
pp. 225-227 ◽  
Author(s):  
Flávio Krzyzanowsky ◽  
Mario J. Avila-Campos
Keyword(s):  
Acute Diarrhea ◽  
Bacteroides Fragilis ◽  
Cytotoxicity Assay ◽  
Toxin Gene ◽  
Gene Detection ◽  
Enterotoxin Production ◽  
Bacteroides Fragilis Group ◽  
Stool Samples ◽  
Ht 29

Non-enterotoxigenic bacteria of the Bacteroides fragilis group and enterotoxigenic B. fragilis were identified from children with and without aqueous acute diarrhea. In this study, 170 stool samples from 96 children with and 74 without diarrhea were analyzed. Enterotoxin production and the toxin gene detection were detected by cytotoxicity assay on HT-29/C1 cells and by PCR, respectively. B. fragilis species was prevalent in both groups and enterotoxigenic B. fragilis strains were isolated from two children with diarrhea. More studies are important to evaluate the role of each bacteria of the B. fragilis group, including enterotoxigenic strains play in the diarrheal processes in children.

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