Screening by a double-disk synergy test identified a Pseudomonas aeruginosa isolate that produced a clavulanic acid-inhibited expanded-spectrum ␤-lactamase (ESBL). Cloning and sequencing identified a novel ESBL, BEL-1, weakly related to other Ambler class A ESBLs. ␤-Lactamase BEL-1 hydrolyzed significantly most expanded-spectrum cephalosporins and aztreonam, and its activity was inhibited by clavulanic acid, tazobactam, cefoxitin, moxalactam, and imipenem. This chromosome-encoded ESBL gene was embedded in a class 1 integron containing three other gene cassettes. In addition, this integron was bracketed by Tn1404 transposon sequences at its right end and by P. aeruginosa-specific sequences at its left end.Clavulanic acid-inhibited Ambler class A extended-spectrum ␤-lactamases (ESBLs) are rarely reported in Pseudomonas aeruginosa. To date, there have been five reports of TEM-and SHV-type ESBLs in P. aeruginosa (SHV-2a, SHV-5, TEM-4, TEM-24, and TEM-42), and three non-TEM-, non-SHV-type ESBLs have also been reported in that species (PER-1, VEBlike, and GES-like ␤-lactamases) (35). The bla PER-1 ␤-lactamase gene is most widespread in Turkey (33), VEB-1 is most widespread in Southeast Asia (9), and GES-like ␤-lactamases have been identified in French, Greek, and South African isolates (8,16,26). Interestingly, GES-2, a point mutant derivative of GES-1 that was identified in South Africa, possessed an ability to hydrolyze not only expanded-spectrum cephalosporins but also imipenem (27).The genetic vehicles that carry ESBL genes are variable. The bla TEM genes are part of Tn1, Tn2, and Tn3 transposon structures (19), bla SHV genes are part of IS26-related transposon structures, and bla PER-1 is part of a peculiar composite transposon, Tn1213, made of two different insertion sequence elements belonging to the IS4 family (21). The bla VEB and bla GES genes are in the form of gene cassettes integrated into class 1 integrons (22,24). In addition, a peculiar genetic organization involving 135-bp repeated elements (Re) bracketing a bla VEB-1a gene cassette has been recently identified in a P. aeruginosa isolate from India (2).This study characterized a novel ESBL whose gene was identified in a class 1 integron. MATERIALS AND METHODSBacterial strains. P. aeruginosa clinical isolate 51170 was identified with the API-20 NE system (bioMérieux, Marcy l'Etoile, France). Escherichia coli DH10B was the host for cloning experiments, and in vitro-obtained, rifampin-resistant P. aeruginosa PU21 was used as a recipient strain for transformation experiments (25).Susceptibility testing. Antibiotic-containing disks were used for routine antibiograms by the disk diffusion assay (Sanofi-Diagnostic Pasteur, Marnes-la-Coquette, France) as previously described (20). The double-disk synergy test was performed with disks containing ceftazidime or cefepime and ticarcillin-clavulanic acid on Mueller-Hinton agar plates, and the results were interpreted as described previously (10). MICs were determined by an agar dilution technique with Mueller-Hint...

A Pseudomonas aeruginosa isolate recovered in Belgium produced a novel extended-spectrum ß-lactamase, BEL-2, differing from BEL-1 by a single Leu162Phe substitution. That modification significantly altered the kinetic properties of the enzyme, increasing its affinity for expanded-spectrum cephalosporins. The bla BEL-2 gene was identified from a P. aeruginosa isolate clonally related to another bla BEL-1 -positive isolate.Extended-spectrum ß-lactamases (ESBLs), such as TEM, SHV, PER, VEB, GES, and more recently, CTX-M variants, are reported increasingly to be found in Pseudomonas aeruginosa in various areas (1, 2, 7, 8, 10-12, 15, 17, 21, 23, 27, 28, 30). The BEL-1 ß-lactamase, distantly related to other ESBLs, was identified from a P. aeruginosa isolate from Roeselare, Belgium, which interestingly shows resistance to ticarcillin and ceftazidime but only reduced susceptibility to piperacillin, cefepime, cefpirome, and aztreonam (24). The bla BEL-1 determinant was found as a gene cassette in the chromosome-borne class 1 integron, In120, that includes other resistance genes (aacA4, aadA5, and smr2) and that was part of a Tn1404-type transposon structure (24). Very recently, Bogaerts et al. (5) reported on the diffusion of BEL-1-producing isolates in various hospital centers of Belgium and also found that BEL-1 could be associated with other relevant ␤-lactamases, such as the VIM-1 metallo-␤-lactamase (5).P. aeruginosa isolate 531 (this study) was recovered from a urine sample of a patient hospitalized in Roeselare, Belgium, in February 2007 for pneumonia and was resistant to all ␤-lactams but imipenem (Table 1). A synergy between aztreonam or ceftazidime and clavulanic acid-containing disks suggested the synthesis of an ESBL (19). PCR followed by sequencing using ESBL gene-specific primers (24) identified a novel gene encoding BEL-2, which differs from BEL-1 by a single amino acid substitution (Leu to Phe at Ambler position 162) (3). Transfer of a ß-lactam resistance marker from P. aeruginosa 531 to Escherichia coli or to P. aeruginosa reference strains was unsuccessful by either conjugation or transformation (25). Plasmid extraction performed as described previously (14) did not identify any plasmid, suggesting a chromosomal location of the bla BEL-2 -like gene in P. aeruginosa 531. A pulsed-field gel electrophoresis (PFGE) analysis (4) showed that isolates 531 (BEL-2 positive) and 51170 (BEL-1 positive), recovered from the same geographical area, were clonally related. A PCR mapping approach confirmed the presence of a class 1 integron whose structure was identical to that of In120 of P. aeruginosa 51170 (24) and identified an identical structure in P. aeruginosa 531 (data not shown). Overall, these data suggest that the bla BEL-2 sequence likely resulted from a mutational event that had occurred in In120-carrying P. aeruginosa strains.In order to compare the contributions of BEL-1 and BEL-2 to ß-lactam resistance, the corresponding genes (amplified using primers PreBEL-A [5Ј-AGACGTAAGCCTATAATCTC] and PreBEL-B [5...

No abstract

No abstract

We report what we consider to be the first case of an abscess of the thyroid gland due to Campylobacter fetus subsp. fetus (C. fetus) in a patient suffering from hyperthyroidism. C. fetus is known as a rare and opportunistic pathogen in humans, causing a broad variety of systemic infections. Acquisition by humans is thought to occur through contact with animals or animal products and to start as a gastro-intestinal colonization. The detection of C. fetus in stool is challenging, since culture efforts are generally directed in order to fulfil growth requirements of C.jejuni, a much more common enteric pathogen. Detection of C. fetus in non-stool samples is even more challenging since routine culture doesn't imply prolonged incubation (>72h), selective media and microaerophilic conditions. It is therefore not unlikely that human infections caused by C. fetus occur more often than generally assumed.