Project description:CTX-M-14 beta-lactamase was identified in a stool isolate of Shigella sonnei and in blood isolates of Escherichia coli (one isolate) and Klebsiella pneumoniae (two isolates) from different parts of Korea. The amino acid sequence differed by one amino acid from CTX-M-9 (Ala-231--> Val) and was identical to that of beta-lactamases recently found in China and Japan.
Project description:BackgroundShigellosis is the most common cause of gastrointestinal infections in developing countries. In China, the species most frequently responsible for shigellosis is Shigella flexneri. S. flexneri remains largely unexplored from a genomic standpoint and is still described using a vocabulary based on biochemical and serological properties. Moreover, increasing numbers of ESBL-producing Shigella strains have been isolated from clinical samples. Despite this, only a few cases of ESBL-producing Shigella have been described in China. Therefore, a better understanding of ESBL-producing Shigella from a genomic standpoint is required. In this study, a S. flexneri type 1a isolate SP1 harboring blaCTX-M-14, which was recovered from the patient with diarrhea, was subjected to whole genome sequencing.ResultsThe draft genome assembly of S. flexneri strain SP1 consisted of 4,592,345 bp with a G+C content of 50.46%. RAST analysis revealed the genome contained 4798 coding sequences (CDSs) and 100 RNA-encoding genes. We detected one incomplete prophage and six candidate CRISPR loci in the genome. In vitro antimicrobial susceptibility testing demonstrated that strain SP1 is resistant to ampicillin, amoxicillin/clavulanic acid, cefazolin, ceftriaxone and trimethoprim. In silico analysis detected genes mediating resistance to aminoglycosides, β-lactams, phenicol, tetracycline, sulphonamides, and trimethoprim. The bla CTX-M-14 gene was located on an IncFII2 plasmid. A series of virulence factors were identified in the genome.ConclusionsIn this study, we report the whole genome sequence of a blaCTX-M-14-encoding S. flexneri strain SP1. Dozens of resistance determinants were detected in the genome and may be responsible for the multidrug-resistance of this strain, although further confirmation studies are warranted. Numerous virulence factors identified in the strain suggest that isolate SP1 is potential pathogenic. The availability of the genome sequence and comparative analysis with other S. flexneri strains provides the basis to further address the evolution of drug resistance mechanisms and pathogenicity in S. flexneri.
Project description:Organisms producing extended-spectrum beta-lactamases (ESBLs) have been reported in many countries, but there is no information on the prevalence of ESBL-producing members of the family Enterobacteriaceae in Cameroon. A total of 259 Enterobacteriaceae strains were isolated between 1995 and 1998 from patients at the Yaounde Central Hospital in Cameroon. Enterobacterial isolates resistant to extended-spectrum cephalosporin and monobactam were screened for ESBL production by the double-disk (DD) synergy test. Thirty-one (12%) of these Enterobacteriaceae strains were shown to be positive by the DD synergy test, suggesting the presence of ESBLs. Resistance to oxyimino-cephalosporins and monobactams of 12 (38.7%) of the 31 strains-i.e., 6 Klebsiella pneumoniae, 4 Escherichia coli, 1 Citrobacter freundii, and 1 Enterobacter cloacae strain-was transferred to E. coli HK-225 by conjugation. Resistance to gentamicin, gentamicin plus trimethoprim-sulfamethoxazole, or trimethoprim-sulfamethoxazole was cotransferred into 6, 2, and 1 of these transconjugants, respectively. All 12 transconjugants were resistant to amoxicillin, piperacillin, all of the cephalosporins, and aztreonam but remained susceptible to cefoxitin and imipenem. Crude extracts of beta-lactamase-producing transconjugants were able to reduce the diameters of inhibition zones around disks containing penicillins, narrow- to expanded-spectrum cephalosporins or monobactams when tested against a fully susceptible E. coli strain but had no effect on such zones around cefoxitin, imipenem, and amoxicillin-clavulanate disks. The beta-lactamases produced by the 12 tranconjugants turned out to be SHV-12 by DNA sequencing. Therefore, the ESBL SHV-12 is described for the first time in Cameroon.
Project description:The clinical strain Escherichia coli TO799 was resistant to penicillin-clavulanate combinations and ceftazidime and was not reproducibly detected as an extended-spectrum beta-lactamase (ESBL) according to the standards of the Clinical Laboratory Standards Institute (CLSI; formerly NCCLS) and the national guidelines of the French Society for Microbiology (Comité de l'Antibiogramme de la Société Française de Microbiologie). A novel beta-lactamase, designated TEM-125, was responsible for this phenotype. TEM-125 harbors a complex association of mutations previously described in the ESBL TEM-12 and in the inhibitor-resistant beta-lactamase TEM-39. TEM-125 is the first complex mutant TEM to present hydrolytic activity against ceftazidime (kcat, 3.7 s(-1)) together with a high level of resistance to clavulanate (50% inhibitory concentration, 13.6 microM). The discovery of such an ESBL, which is difficult to detect by the usual ESBL detection methods, confirms the emergence of a complex mutant TEM subgroup and highlights the need to evaluate detection methods so as to avoid possible therapeutic failures.
Project description:An Aeromonas allosaccharophila environmental isolate recovered from the Seine River (Paris, France) produced a novel extended-spectrum beta-lactamase, PER-6, that shared 92% amino acid identity with the closest ss-lactamase, PER-2. The kinetic properties of PER-6 showed a slightly increased affinity for carbapenems. The bla(PER-6) gene was chromosomally located and bracketed by non-transposon-related structures.
Project description:A clinical isolate of Pseudomonas aeruginosa RP-1 produced the extended-spectrum beta-lactamase (ESBL) SHV-2a. Its gene was expressed from a composite promoter made of the -35 region derived from the left inverted repeat of IS26 and the -10 region from the blaSHV-2a promoter itself. The DNA sequences immediately surrounding blaSHV-2a were homologous to plasmid pMPA2a from Klebsiella pneumoniae KpZU-3, while further away and 3' to the blaSHV-2a gene, a sequence corresponding to the left end of Tn1721 was detected, thus indicating a likely enterobacterial origin of this ESBL gene.
Project description:A novel natural TEM beta-lactamase with extended-spectrum activity, TEM-138, was identified in a ceftazidime-resistant clinical isolate of Salmonella enterica serovar Infantis. Compared to TEM-1, TEM-138 contains the following mutations: E104K, N175I, and G238S. The bla(TEM-138) gene was located on a 50-kb transferable plasmid. Expression studies with Escherichia coli revealed efficient ceftazidimase and cefotaximase activities for TEM-138.
Project description:A new natural TEM derivative with extended-spectrum beta-lactamase activity, TEM-134, was identified in a ceftazidime-resistant clinical isolate of Citrobacter koseri. Compared to TEM-1, TEM-134 contains the following mutations: Q39K, E104K, R164H, and G238S. The bla(TEM-134) gene was not transferable by conjugation and, apparently, was chromosomally encoded. Expression studies with Escherichia coli revealed efficient cefotaximase and ceftazidimase activity for TEM-134.