recA and glnA sequences separate the Bacteroides fragilis population into two genetic divisions associated with the antibiotic resistance genotypes cepA and cfiA

Gutacker, Michaela; Valsangiacomo, Claudio; Bernasconi, Marco Valerio; Piffaretti, Jean-Claude

doi:10.1099/0022-1317-51-2-123

Cited by 23 publications

(22 citation statements)

References 20 publications

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“…Furthermore, CTn86 and CTn86-like elements were found exclusively in cepA-positive/cfiA-negative strains, and 95% of CTn9343 and CTn9343-like elements were also found in cepA-positive/ cfiA-negative strains. These results are in agreement with previous reports that found ETBF exclusively in cepA-positive/ cfiA-negative strains (10,11). These studies and others showed that cepA and cfiA never are in the same B. fragilis strain and that these genes are associated with distinct genetic divisions of B. fragilis: cepA is present only in division I and cfiA is present only in division II (10,11,25).…”

Section: Discussionsupporting

confidence: 83%

“…These studies and others showed that cepA and cfiA never are in the same B. fragilis strain and that these genes are associated with distinct genetic divisions of B. fragilis: cepA is present only in division I and cfiA is present only in division II (10,11,25). Due to the genetic distance observed between these two divisions by different genotyping approaches, it has been suggested that these divisions may represent different species (10,11,25).…”

Section: Discussionmentioning

confidence: 99%

“…Division II is characterized by the presence of cfiA and absence of cepA. ETBF strains have been found exclusively in division I (cepA-positive/cfiA-negative strains) (10,11).…”

Section: Vol 73 2007 Ctn86 and Ctn9343 In B Fragilis Strains 57mentioning

confidence: 99%

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Identification and Characterization of Conjugative Transposons CTn86 and CTn9343 in Bacteroides fragilis Strains

Buckwold

Shoemaker

Sears

et al. 2007

Appl Environ Microbiol

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The related genetic elements flanking the Bacteroides fragilis pathogenicity island (PAI) in enterotoxigenic B. fragilis (ETBF) 86-5443-2-2 and also present in pattern III nontoxigenic B. fragilis (NTBF) NCTC 9343 were defined as putative conjugative transposons (CTns), designated CTn86 and CTn9343, respectively (A. A. Franco, J. Bacteriol. 181:6623-6633, 2004). CTn86 and CTn9343 have the same basic structures except that their encoded transposases have low similarity and CTn9343 lacks the B. fragilis PAI and contains an extra 7-kb region not present in CTn86. In this study, using DNA hybridization and PCR analysis, we characterized the genetic element flanking the PAI in a collection of ETBF strains and the related genetic elements in a collection of NTBF pattern III strains. We found that in all 123 ETBF strains, the PAI is contained in a genetic element similar to CTn86. Of 73 pattern III strains, 26 (36%) present a genetic element similar to CTn9343, 38 (52%) present a genetic element similar to CTn9343 but lack the 7-kb region that is also absent in CTn86 (CTn9343-like element), and 9 (12%) present a genetic element similar to CTn86 but lacking the PAI (CTn86-like element). In addition to containing CTn86, ETBF strains can also contain CTn9343, CTn9343-like, or CTn86-like elements. CTn86, CTn9343, CTn86-like, and CTn9343-like elements were found exclusively in B. fragilis strains and predominantly in division I, cepA-positive strains.Enterotoxigenic Bacteroides fragilis (ETBF) is strongly associated epidemiologically with diarrheal disease in livestock, young children, and adults (19,20,21,29,30,32,40). The only recognized virulence factor of ETBF is a toxin termed B. fragilis toxin, or BFT (16,34,35). Three highly related isotypes of BFT (termed BFT-1, BFT-2, and BFT-3) have been identified (3, 6). It has been reported that the bft gene is contained in a 6-kb pathogenicity island (PAI) and that the B. fragilis PAI is flanked by genes encoding mobilization proteins (7,17). Based on the presence of the PAI and its flanking region, three major populations of B. fragilis strains were identified: (i) pattern I strains, containing the PAI and its flanking region, which are all ETBF strains; (ii) pattern II strains, lacking the PAI and its flanking regions, which are all nontoxigenic B. fragilis (NTBF) strains; and (iii) pattern III strains, containing the flanking region but lacking the PAI, which are all NTBF strains (7).The GϩC content of the B. fragilis PAI (35%) and of the flanking DNA (47 to 50%) differs greatly from that reported for the B. fragilis chromosome (43%) (2, 14), suggesting that the PAI and its flanking region are two distinct genetic elements originating from different organisms. Based on these results, it was hypothesized that ETBF strains may have evolved by horizontal transfer of these two genetic elements into a pattern II NTBF strain (7). It was recently determined that the genetic element flanking the PAI in ETBF 86-5443-2-2 (pattern I; contains the PAI) and a related genetic element in ...

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

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Identification and Characterization of Conjugative Transposons CTn86 and CTn9343 in Bacteroides fragilis Strains

Buckwold

Shoemaker

Sears

et al. 2007

Appl Environ Microbiol

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“…As can be seen in Table 1, higher MIC values were observed for these antibiotics in strains where the cepA gene was detected than in strains 119 and AK-2 (cepA À ). Gutacker et al (2002) concluded that the â-lactamaseencoding genes cepA and cfiA were never found together in the same isolate. This apparent mutual exclusion may be explained by the acquisition of these genes in separate and unique events.…”

Section: Resultsmentioning

confidence: 99%

Relationship between penicillin-binding protein patterns and β-lactamases in clinical isolates of Bacteroides fragilis with different susceptibility to β-lactam antibiotics

Píriz

Vadillo

Quesada

et al. 2004

Journal of Medical Microbiology

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This study examines the role of the penicillin-binding proteins (PBPs) of Bacteroides fragilis in the mechanism of resistance to different â-lactam antibiotics. Six of the eight strains used were â-lactamase-positive by the nitrocefin assay. These strains displayed reduced susceptibility to imipenem (MIC, 2-16 mg l À1 ) and some of them were resistant to the actions of ampicillin, cefuroxime, cephalexin, cefoxitin and piperacillin. When studying specific enzymic activity, the capacity to degrade cefuroxime was only detected in strains AK-4, R212 and 0423 and the capacity to degrade cephalexin was only detected in strains R212 and 2013E; no specific activity was detected on imipenem. Metallo-â-lactamase activity was only detected in strains AK-2 and 119, despite the fact that the cfiA gene was identified in four strains (AK-2, 2013E, 119 and 7160). The cepA gene was detected in six of the eight strains studied. Three high-molecular-mass PBPs were detected in all strains; however, in some cases, PBP2Bfr and/or PBP3Bfr appeared as a faint band. PBP4Bfr and PBP5Bfr were detected in six strains. PBP6Bfr only was detected in B. fragilis strains AK-2, 0423, 119 and 7160. By analysis of the sequence of B. fragilis chromosomal DNA and comparison with genes that are known to encode PBPs in Escherichia coli, six genes that encode PBP-like proteins were detected in the former organism. The gene that encodes the PBP2 orthologue of E. coli (pbpABfr, PBP3Bfr) was sequenced in six of the eight strains and its implications for resistance were examined. Differences in the PBP3Bfr amino acid sequences of strains AK-2 and 119 and their production of â-lactamases indicate that these differences are not involved in the mechanism of resistance to imipenem and/or cephalexin.

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“…By using various molecular typing methods, such as arbitrarily primed PCR, ribotyping, multilocus enzyme electrophoresis, and sequencing of recA and glnA genes, cfiA-negative and cfiA-positive strains were shown to belong to two genotypically distinct groups (9,10,13). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has the capacity to discriminate closely related species based on the spectrum of constantly expressed highly abundant proteins, such as ribosomal proteins.…”

mentioning

confidence: 99%

Differentiation of cfiA -Negative and cfiA -Positive Bacteroides fragilis Isolates by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

et al. 2011

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Carbapenem resistance in Bacteroides fragilis is associated with cfiA-encoded class B metallo-beta-lactamase. cfiA-negative and cfiA-positive isolates belong to genotypically distinct groups. Of a total of 248 B. fragilis isolates included in this study, 214 were susceptible, 10 were intermediate, and 24 were resistant to meropenem. We show that matrix-assisted laser desorption ionization-time of flight mass spectrometry is able to differentiate between cfiA-negative and cfiA-positive isolates and predict carbapenem resistance in a routine laboratory setting.Bacteroides fragilis is a strictly anaerobic Gram-negative bacillus present in the human gut. It is recovered from various infection sites and frequently associated with abscess formation and sepsis. Carbapenem resistance in B. fragilis is emerging and associated with cfiA-encoded class B metallo-betalactamase, which is activated by insertion sequence (IS) elements. However, elevated MICs or resistance was also observed in strains that did not have activating IS elements in the upstream region of cfiA (17). In the 2003-2005 Belgian multicenter survey (18), the prevalence of the cfiA resistance gene was 7.4% (10/135) (19), which is high compared with the prevalence of cfiA positivity (2 to 7%) in other countries (5,6,13,15,20). In the survey, 4% (6/135) of B. fragilis isolates were intermediate or resistant to meropenem according to CLSI breakpoints (18).By using various molecular typing methods, such as arbitrarily primed PCR, ribotyping, multilocus enzyme electrophoresis, and sequencing of recA and glnA genes, cfiA-negative and cfiA-positive strains were shown to belong to two genotypically distinct groups (9, 10, 13). Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has the capacity to discriminate closely related species based on the spectrum of constantly expressed highly abundant proteins, such as ribosomal proteins. This technique was recently introduced as a rapid and accurate method for the identification of bacteria (2,7,14) and can also be applied in the identification of Bacteroides isolates (12). The aim of the present study was to examine the discriminatory power of MALDI-TOF MS to differentiate cfiA-positive from cfiA-negative B. fragilis strains in order to predict carbapenem susceptibility.The 135 B. fragilis clinical isolates from the survey mentioned above (18, 19), originating from nine Belgian hospitals, as well as 113 B. fragilis isolates from routine cultures collected at our laboratory since 2005 were analyzed. Identification was performed by appropriate biochemical and enzymatic tests (11) and confirmed by MALDI-TOF MS. Meropenem susceptibility was determined by Etest methodology (bioMérieux, Marcy l'Etoile, France). The CLSI breakpoints for susceptible and resistant strains are Յ4 mg/liter and Ն16 mg/liter, respectively (4). PCR analysis was performed to detect the presence of the cfiA gene. The annealing temperature of the cfiA gene detection method described by Sóki et al. (16) was increa...

show abstract

recA and glnA sequences separate the Bacteroides fragilis population into two genetic divisions associated with the antibiotic resistance genotypes cepA and cfiA

Cited by 23 publications

References 20 publications

Identification and Characterization of Conjugative Transposons CTn86 and CTn9343 in Bacteroides fragilis Strains

Identification and Characterization of Conjugative Transposons CTn86 and CTn9343 in Bacteroides fragilis Strains

Relationship between penicillin-binding protein patterns and β-lactamases in clinical isolates of Bacteroides fragilis with different susceptibility to β-lactam antibiotics

Differentiation of cfiA -Negative and cfiA -Positive Bacteroides fragilis Isolates by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

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