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- Buhl, Michael E.J., et al.
(författare)
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Antimicrobial resistance surveillance of Bacteroides fragilis isolated from blood cultures, Europe, 2022 (ReSuBacfrag)
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Ingår i: International Journal of Antimicrobial Agents. - 1872-7913.
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundBacteroides fragilis is the most frequent cause of anaerobic bacteraemia. Although recent data suggest a rise in antimicrobial resistance (AMR) of this and other anaerobic bacteria, surveillance remains limited due to a lack of both data availability and comparability. However, a newly introduced standardised method for antimicrobial susceptibility testing (AST) of anaerobic bacteria has made larger scale surveillance possible for the first time.AimTo investigate phenotypic AMR of Bacteroides fragilis isolates from bacteraemia across Europe in 2022.MethodsIn a multicentre approach, clinical microbiology laboratories in Europe were invited to contribute results of AST for Bacteroides fragilis blood culture isolates (including only the first isolate per patient and year). AST of a selection of four antibiotics was performed locally by participating laboratories in a prospective or retrospective manner, using the new EUCAST disc diffusion method on fastidious anaerobe agar (FAA-HB).ResultsA total of 16 European countries reported antimicrobial susceptibilities in 449 unique isolates of Bacteroides fragilis from blood cultures in 2022. Clindamycin demonstrated the highest resistance rates (20.9%, range 0 - 63.6%), followed by piperacillin-tazobactam (11.1%, 0 - 54.5%), meropenem (13.4%, 0 - 45.5%), and metronidazole (1.8%, 0 - 20.0%), all with wide variation between countries.ConclusionConsidering that the mean resistance rates across Europe were higher than expected for three of the four anti-anaerobic antibiotics under surveillance, both local AST of clinically relevant isolates of Bacteroides fragilis and continued surveillance on an international level is warranted.
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| 2. |
- Sóki, József, et al.
(författare)
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Description of Bacteroides strains showing hetero-resistance to cefoxitin and carbapenems
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Objective: Our aim was to document and characterize the hetero-resistant phenotypes, also known for methicillin and vancomycin-resistant Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae, of Bacteroides strains to cefoxitin and carbapenems noticed using Etests for antimicrobial susceptibility testing.Methods: Eight hetero-resistant B. fragilis strains collected during our 10 years experience and 100 clinical B. fragilis group strains recently isolated in Hungary were studied. For in vitro susceptibility measurements of cefoxitin and carbapenems agar dilution and Etest were used. Heteroresistant colonies growing in the ellipse between the E-test strip and main population were further analyzed. The occurrence of cfxA and cfiA resistance genes and their regulatory regions were investigated by PCR and nucleotide sequencing. Population analysis profiles were also investigated.Results: We detected 8 B. fragilis strains hetero-resistant to carbapenems using Etest susceptibility measurements (from 0.25-4 µg/ml of continous growth up to 16-32 µg/ml). All of them were cfiA-positive but did not harbour insertion sequence elements in the upstream region of the resistance genes. Of 100 recently isolated Bacteroides strains, 21 strains hetero-resistant to cefoxitin were observed. Their Etest patterns usually displayed a continuous growth of the less susceptible subpopulation from 8-128 µg/ml up to 256 µg/ml. Of these 21 isolates 11 harbored cfxA genes and their upstream regions were usually altered to the common 1.2 kb fragment, as seen in our previous studies. The population profile analysis demonstrated presence of more resistant subpopulations in the culture of strains corresponding to the more resistant colonies in the Etest ellipse zones. Repeated experiments of subcultures from single colonies taken from the heteroresistant zones resulted in the original hetero-resistant appearance using the Etest method.Conclusion: Hetero-resistance to important β-lactam antibiotics appear among Bacteroides strains but the phenotype could not yet be linked to any particular genetic constitution.This study was supported by a Hungarian National Research Fund grant (K69044).
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| 3. |
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| 4. |
- Soki, Jozsef, et al.
(författare)
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Emergence and evolution of an international cluster of MDR Bacteroides fragilis isolates
- 2016
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 71:9, s. 2441-2448
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the antibiotic resistance profiles, antibiotic resistance mechanisms and possible 'clonal' nature of some MDR Bacteroides fragilis strains that simultaneously harboured cfiA, nimB, IS1186 and IS4351. Antibiotic susceptibilities were determined by Etests and antibiotic resistance genes and different genetic elements were detected by applying PCR methods. The environments of the cfiA and nimB genes were also determined by sequencing. The transferability of the cfiA, nimB and tet(Q) genes was tested by conjugation. The genetic relatedness of the test strains was tested by ERIC-PCR or PFGE. The complete genome sequences of two strains (B. fragilis BF8 and O:21) were determined by next-generation sequencing. Most of the seven B. fragilis strains tested displayed multidrug resistance phenotypes; five strains were resistant to at least five types of antibiotics. Besides the common genetic constitution, ERIC-PCR implied high genetic relatedness. Similarities in some of the antibiotic resistance mechanisms [carbapenems (cfiA) and metronidazole (nimB)] also confirmed their common origin, but some other resistance mechanisms {MLSB [erm(F)] and tetracycline [tet(Q)]} and PFGE typing revealed differences. In B. fragilis BF8 and O:21, erm(F) and tet(X) genes were found with IS4351 borders, thus constituting Tn4351. All the strains were tet(Q) positive and transferred this gene in conjugation experiments, but not the cfiA and nimB genes. An international cluster of MDR B. fragilis strains has been identified and characterized. This 'clone' may have emerged early in the evolution of division II B. fragilis strains, which was suggested by the low-complexity ERIC profiles and differences in the PFGE patterns.
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