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

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.

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

Revista do Instituto de Medicina Tropical de São Paulo ◽

10.1590/s0036-46652000000300005 ◽

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.

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

Türk Mikrobiyoloji Cemiyeti Dergisi ◽

10.5222/tmcd.2021.30075 ◽

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.

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Detection of resistance genes from Pseudomonas aeruginosa using immunomagnetic isolation and chemiluminescence

Materials Express ◽

10.1166/mex.2020.1650 ◽

2020 ◽

Vol 10 (3) ◽

pp. 412-418

Author(s):

Fei Xu ◽

Cheng Chen ◽

Xing Li ◽

Bo Zhang

Keyword(s):

Pseudomonas Aeruginosa ◽

Resistance Genes ◽

High Efficiency ◽

Bacterial Pathogen ◽

Resistance Mechanisms ◽

Clinical Samples ◽

Specific Gene ◽

Beta Lactamases ◽

Immunomagnetic Isolation ◽

Encoding Gene

Pseudomonas aeruginosa (P. aeruginosa) is a common opportunistic and nosocomial bacterial pathogen. Various multi-resistance mechanisms present across numerous P. aeruginosa strains counteract conventional antimicrobial therapy, thereby becoming a great challenge. This study aimed to establish the application of immunomagnetic isolation and chemiluminescence to detect the presence of extended spectra of β-lactamases encoding genes: blaTEM and blaVEB; metallo-beta-lactamases encoding gene: blaVIM; aminoglycoside modifying enzymes encoding gene: aac(6)II, ant(3)I; and the specific gene for P. aeruginosa, gyrB. P. aeruginosa was specifically selected using the immunomagnetic nanoparticles (IMNPs) in the six parallel bacterial plates counting, proving that they are reliable. Then, the high efficiency of IMNPs@Probes in targeting the resistance genes of P. aeruginosa was demonstrated using the results of chemiluminescent intensities of blaTEM, blaVEB, blaVIM aac(6)II, ant(3)I, and gyrB (more than 10 times higher than that of the control). Sixty-eight in situ clinical samples were tested for the presence of these resistance genes, and one more blaTEM and three more blaVIM individuals were detected using this method compared to the traditional PCR. Thus, the application of our method in clinical screening is specific, accurate, and reliable, and it could be useful in the administration of appropriate treatment.

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The prevalence of enterotoxin and antibiotic resistance genes in clinical and intestinal Bacteroides fragilis group isolates in Turkey

Anaerobe ◽

10.1016/j.anaerobe.2015.07.008 ◽

2015 ◽

Vol 35 ◽

pp. 72-76 ◽

Cited By ~ 6

Author(s):

Achille Aime Kangaba ◽

Filiz Yarimcam Saglam ◽

Hrisi Bahar Tokman ◽

Mert Torun ◽

Muzeyyen Mamal Torun

Keyword(s):

Antibiotic Resistance ◽

Resistance Genes ◽

Bacteroides Fragilis ◽

Antibiotic Resistance Genes ◽

Bacteroides Fragilis Group

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

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.5.1037 ◽

1997 ◽

Vol 41 (5) ◽

pp. 1037-1041 ◽

Cited By ~ 26

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.

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Comparative evaluation of agar dilution and broth microdilution by commercial and in-house plates for Bacteroides fragilis group: An economical and expeditious approach for resource-limited settings

Anaerobe ◽

10.1016/j.anaerobe.2021.102443 ◽

2021 ◽

pp. 102443

Author(s):

Anshul Sood ◽

Archana Angrup ◽

Pallab Ray ◽

Kiran Bala

Keyword(s):

Comparative Evaluation ◽

Bacteroides Fragilis ◽

Broth Microdilution ◽

Resource Limited Settings ◽

Resource Limited ◽

Bacteroides Fragilis Group ◽

Agar Dilution

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Fusidic Acid Resistance Rates and Prevalence of Resistance Mechanisms among Staphylococcus spp. Isolated in North America and Australia, 2007-2008

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01390-09 ◽

2010 ◽

Vol 54 (9) ◽

pp. 3614-3617 ◽

Cited By ~ 51

Author(s):

Mariana Castanheira ◽

Amy A. Watters ◽

Jan M. Bell ◽

John D. Turnidge ◽

Ronald N. Jones

Keyword(s):

United States ◽

Resistance Genes ◽

Fusidic Acid ◽

Dominant Role ◽

Acquired Resistance ◽

Resistance Mechanism ◽

Acid Resistance ◽

The United States ◽

Resistance Mechanisms ◽

Resistance Rates

ABSTRACT Among 4,167 Staphylococcus aureus and 790 coagulase-negative Staphylococcus (CoNS; not S. saprophyticus) isolates collected consecutively from North American and Australian hospitals, only 87 (1.7% overall) isolates displayed a fusidic acid (FA; also known as CEM-102) MIC of ≥2 μg/ml (FA resistance). These strains were further evaluated with a multiplex PCR to amplify the acquired resistance genes fusB, fusC, and fusD. Mutations in fusA and fusE were evaluated in all isolates showing an absence of acquired resistance genes and/or showing FA MIC values of ≥64 μg/ml. S. aureus resistance rates were very low in the United States (0.3%) and were higher in Canada and Australia (7.0% for both countries). Among CoNS isolates, FA resistance rates were significantly more elevated than that for S. aureus (7.2 to 20.0%; the highest rates were in Canada). All 52 (41 CoNS) FA-resistant isolates from the United States showed FA MIC results of ≤64 μg/ml, and 7 of 11 S. aureus isolates carried fusC. CoNS strains from the United States carried fusB or fusC. In Canada, fusB and fusC occurrences were similar among S. aureus and CoNS isolates, and modestly elevated FA MIC values were observed (all MIC results were ≤32 μg/ml). Isolates from Australia showed MIC values ranging from 2 to 32 μg/ml, and S. aureus isolates were predominantly fusC positive. fusA mutations were detected in only three S. aureus isolates, conferring FA MIC values of 2 to 8 μg/ml. Target mutations have been considered the primary FA resistance mechanism among Staphylococcus spp.; however, acquired resistance genes appear to have a dominant role in resistance against this older antimicrobial agent. In summary, this study shows that acquired genes are highly prevalent among FA-resistant strains (>90%) in three nations with distinct or absence (United States) of fusidic acid clinical use.

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

Canadian Journal of Microbiology ◽

10.1139/m87-044 ◽

1987 ◽

Vol 33 (3) ◽

pp. 262-266 ◽

Cited By ~ 2

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.

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Surveillance of Antimicrobial Susceptibility of Anaerobe Clinical Isolates in Southeast Austria: Bacteroides fragilis Group Is on the Fast Track to Resistance

Antibiotics ◽

10.3390/antibiotics10050479 ◽

2021 ◽

Vol 10 (5) ◽

pp. 479

Author(s):

Elisabeth König ◽

Hans P. Ziegler ◽

Julia Tribus ◽

Andrea J. Grisold ◽

Gebhard Feierl ◽

...

Keyword(s):

Antimicrobial Susceptibility ◽

Anaerobic Bacteria ◽

Bacteroides Fragilis ◽

Beta Lactam ◽

Gram Positive ◽

Beta Lactam Antibiotics ◽

Disk Diffusion Testing ◽

Bacteroides Fragilis Group ◽

Resistance Rates ◽

Human Infections

Anaerobic bacteria play an important role in human infections. Bacteroides spp. are some of the 15 most common pathogens causing nosocomial infections. We present antimicrobial susceptibility testing (AST) results of 114 Gram-positive anaerobic isolates and 110 Bacteroides-fragilis-group-isolates (BFGI). Resistance profiles were determined by MIC gradient testing. Furthermore, we performed disk diffusion testing of BFGI and compared the results of the two methods. Within Gram-positive anaerobes, the highest resistance rates were found for clindamycin and moxifloxacin (21.9% and 16.7%, respectively), and resistance for beta-lactams and metronidazole was low (<1%). For BFGI, the highest resistance rates were also detected for clindamycin and moxifloxacin (50.9% and 36.4%, respectively). Resistance rates for piperacillin/tazobactam and amoxicillin/clavulanic acid were 10% and 7.3%, respectively. Two B. fragilis isolates were classified as multi-drug-resistant (MDR), with resistance against all tested beta-lactam antibiotics. The comparative study of 109 BFGI resulted in 130 discrepancies in 763 readings (17%) with a high number of Very Major Errors (VME) and Major Errors (ME). In summary, resistance rates, with the exception of clindamycin and moxifloxacin, are still low, but we are facing increasing resistance rates for BFGI. Surveillance studies on a regular basis are still recommended.

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Known mechanisms account for less than half of antimicrobial resistance in a diverse collection of non-aureus staphylococci.

10.1101/2021.06.22.449369 ◽

2021 ◽

Author(s):

Heather Felgate ◽

Lisa C Crossman ◽

Elizabeth Gray ◽

Rebecca Clifford ◽

John Wain ◽

...

Keyword(s):

Antimicrobial Resistance ◽

Resistance Genes ◽

Antimicrobial Susceptibility ◽

Methicillin Resistance ◽

Clinical Intervention ◽

Clinical Samples ◽

Healthy Human ◽

Genetic Mechanisms ◽

Healthcare Acquired Infections ◽

Agar Dilution

Introduction: Non-aureus staphylococci (NAS) are implicated in many healthcare-acquired infections and an understanding of the genetics of antimicrobial resistance in NAS is important in relation to both clinical intervention and the role of NAS as a reservoir of resistance genes. Gap statement: The burden of antimicrobial resistance in NAS, particularly to clinically relevant antimicrobials, is understudied. Methodology: We sourced 394 NAS isolates from clinical samples, healthy human volunteers, animals and type cultures and subjected them to agar dilution susceptibility testing against eight antimicrobials. We performed whole genome sequencing on 316 isolates and analysed these genotypically for the presence of genetic mechanisms responsible for the phenotypic levels of reduced antimicrobial susceptibility. Results: Cefoxitin is used to screen for methicillin resistance in S. aureus, as it stimulates expression of mecA. We observed 174 isolates with an MIC of at least 4 μg/ml to cefoxitin, of which sequencing revealed 47.6% (80/168) did not harbour a known mec homologue. Seven clinical NAS isolates displayed high daptomycin minimum inhibitory concentrations (MICs) (>4 μg/ml), with no known mechanism identified. Differences in MICs against erythromycin were attributable to the presence of different resistance genes (msrA and ermC). In total, 49% (187/394) of isolates displayed reduced susceptibility to three or more of the antimicrobials tested. Conclusions: The widespread presence of reduced antimicrobial susceptibility in NAS is a concern, with an increased likelihood of (1) harder to treat infections caused directly by NAS, and (2) resistance genes being passed on to other bacteria via horizontal gene transfer, both of which have clinical implications for treatment and management of patients.

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