RESUMO
Nine epidemiologically unrelated isolates [1 Salmonella Bredeney from turkeys, and 8 Escherichia coli [3 environmental isolates (2 from chickens, 1 from pigs), and 5 isolates from cattle with neonatal diarrhea]] were examined both pheno- and genotypically for extended-spectrum beta-lactam (ESBL) resistance. Resistance phenotypes (ampicillin, aztreonam, cefotaxime, cefpodoxime, ceftazidime, and ceftriaxone) suggested the presence of an ESBL enzyme, but cefoxitin MICs (>/= 32 mg/L) suggested the presence of an AmpC-like enzyme. Synergism experiments with benzo(b)thiophene-2-boronic acid (BZBTH2B) and isoelectric focusing (IEF) revealed the presence of an AmpC beta-lactamase with a pI >/= 9. amp C multiplex PCR, sequence, and Southern analyses indicated that only the Salmonella isolate had a plasmid-encoded AmpC beta-lactamase CMY-2 on a nonconjugative 60-MDa plasmid. PCR and sequence analysis of the E. coli ampC promoter identified mutations at positions -88(T), -82(G), -42(T), -18(A), -1(T) and +58(T) in all the isolates. In addition one strain had two extra-mutations at positions +23(A) and +49(G), and another strain had one extra-mutation at position +32(A). DNA fingerprinting revealed that all the E. coli isolates were different clones. It also showed that the U.K. Salmonella isolate was indistinguisable from a Canadian Salmonella isolate from turkeys; both had identical resistance phenotypes and produced CMY-2. This is the first report of a CMY-2 Salmonella isolate in the United Kingdom. These data imply that beta-lactam resistance in animal isolates can be generated de novo as evidenced by the E. coli strains, or in the case of the Salmonella strains be the result of intercontinental transmission due to an acquired resistance mechanism.
Assuntos
Animais Domésticos/microbiologia , Resistência às Cefalosporinas/genética , Cefalosporinas/farmacologia , Escherichia coli/efeitos dos fármacos , Salmonella enterica/efeitos dos fármacos , beta-Lactamases/metabolismo , Animais , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Ácidos Borônicos/farmacologia , Cefoxitina/farmacologia , Conjugação Genética , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Escherichia coli/enzimologia , Escherichia coli/genética , Genótipo , Focalização Isoelétrica , Testes de Sensibilidade Microbiana , Fenótipo , Plasmídeos/genética , Salmonella enterica/enzimologia , Salmonella enterica/genética , Tiofenos/farmacologia , Reino Unido , Resistência beta-Lactâmica , Inibidores de beta-Lactamases , beta-Lactamases/genéticaRESUMO
Salmonella enterica serovar Enteritidis is a common cause of salmonellosis in people in the UK. This study aimed to assess the degree of genetic diversity among animal and human isolates from UK, Wales and northern Ireland. A total of 250 isolates from humans (n = 59) and animals or their environment (n = 191), belonging to the most common phage-types, were fingerprinted by a combination of PFGE, PS ribotyping and plasmid profiling. The different techniques identified different degrees of polymorphism (PS ribotyping (52 types) > PFGE (22 types) > plasmid profiling (17 types)). A prevalent genomic clone, as well as a variety of less frequent clones are present for each of the phage-types. In most cases, the prevalent clones appeared within isolates from several animal species and from several geographical locations. The percentage of sporadic clones found in animal and human populations were very similar. There was not clear evidence of a higher degree of diversity for human or animal isolates. Some clones were found to be present in both human and animal.
Assuntos
Salmonella enteritidis/genética , Animais , Tipagem de Bacteriófagos/métodos , Impressões Digitais de DNA , DNA Bacteriano/química , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Microbiologia de Alimentos , Variação Genética , Humanos , Plasmídeos , Ribotipagem , Infecções por Salmonella/microbiologia , Salmonella enteritidis/classificação , Salmonella enteritidis/isolamento & purificação , Reino UnidoRESUMO
Salmonella enterica serotype Typhimurium is a common cause of salmonellosis among humans and animals in England, Wales, and Northern Ireland. Phage types DT104 and U302 were the most prevalent types in both livestock and humans in 2001. In addition, Salmonella serotype Typhimurium DT204b was responsible for a recent international outbreak involving England. A total of 119 isolates from humans (n = 28) and animals or their environment (n = 91), belonging to DT104 (n = 66), U302 (n = 33), DT204b (n = 12), and DT49 (n = 8), were fingerprinted by a combination of well-established genetic methods (pulsed-field gel electrophoresis [PFGE], PstI/SphI [PS] ribotyping, and plasmid profiling). The different techniques identified different degrees of polymorphism (from greatest to least, plasmid profiling [40 types], PS ribotyping [34 types], and PFGE [23 types]). It seems clear that a prevalent genomic clone, as well as a variety of less frequent clones, is present for each of the phage types. In most cases, the prevalent clones appeared within isolates from several animal species and from several geographical locations. We did not find clear evidence of a higher degree of diversity for any of the animal species included, or of any link between isolates from particular animal species and humans. The data presented show the inaccuracy of drawing epidemiological conclusions based on a single fingerprinting method. Strains that share one of the markers do not necessarily belong to the same clone, and a multiple typing approach is required to enable enough discrimination to track strains for epidemiological investigations.
Assuntos
Técnicas de Tipagem Bacteriana , Salmonelose Animal/microbiologia , Infecções por Salmonella/microbiologia , Salmonella typhimurium/classificação , Salmonella typhimurium/genética , Animais , Tipagem de Bacteriófagos , Gatos , Bovinos , Cães , Eletroforese em Gel de Campo Pulsado , Inglaterra , Genótipo , Humanos , Irlanda do Norte , Plasmídeos , Ribotipagem , Fagos de Salmonella/classificação , Salmonella typhimurium/virologia , Sorotipagem , País de GalesRESUMO
This study is focused on real-time detection of gyrA mutations and of the presence of class I integrons in a panel of 100 veterinary isolates of Salmonella enterica from farm animals. The isolates were selected on the basis of resistance to nalidixic acid, representing a variety of the most prevalent serotypes in England and Wales. In addition, organic solvent (cyclohexane) resistance in these isolates was investigated in an attempt to elucidate the presence of efflux pump mechanisms. The most prevalent mutation among the isolates studied was Asp87-Asn (n = 42), followed by Ser83-Phe (n = 38), Ser83-Tyr (n = 12), Asp87-Tyr (n = 4), and Asp87-Gly (n = 3). Two distinct subpopulations were identified, separated at the 1-mg/liter breakpoint for ciprofloxacin: 86% of isolates with mutations in codon 83 showed MICs of >or=1 mg/liter, while 89.8% of isolates with mutations in codon 87 presented MICs of