RESUMO
Cholera epidemics with moderately high case fatality rates in Assam, northeast India were investigated in 2007, 2008 and 2010. Based on mismatch amplification mutation assay PCR for detection of ctxB allele, 40 isolates of Vibrio cholerae O1 El Tor collected from the epidemics were found to harbour the classical ctxB gene allele of cholera toxin (CT). DNA sequencing of ctxB gene confirmed the isolates to be genotype 1 of ctxB. Antimicrobial susceptibility tests reveal that 100% of the isolates were resistant to trimethoprim and 40% were resistant to tetracycline. The recent V. cholerae O1 strains circulating in Assam, India are due to the El Tor variant carrying classical type CT. Emergence of tetracycline and trimethoprim resistant strains necessitates the review of antibiotic use for severe cholera.
Assuntos
Toxina da Cólera/genética , Cólera/genética , Resistência a Tetraciclina/genética , Resistência a Trimetoprima/genética , Vibrio cholerae O1/efeitos dos fármacos , Cólera/tratamento farmacológico , Cólera/epidemiologia , Toxina da Cólera/imunologia , DNA Bacteriano/isolamento & purificação , Feminino , Humanos , Incidência , Índia/epidemiologia , Masculino , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Reação em Cadeia da Polimerase , Resistência a Tetraciclina/imunologia , Resistência a Trimetoprima/imunologia , Vibrio cholerae O1/genética , Vibrio cholerae O1/isolamento & purificação , Vibrio cholerae O1/patogenicidadeRESUMO
OBJECTIVE: To explore further the association of antibiotic treatment-resistant Lyme arthritis and T cell reactivity with outer surface protein A (OspA) of Borrelia burgdorferi, including the identification of T cell epitopes associated with this treatment-resistant course. METHODS: The responses of peripheral blood and, if available, synovial fluid lymphocytes to B burgdorferi proteins, fragments, and synthetic peptides, as determined by proliferation assay and interferon-gamma production, were compared in 16 patients with treatment-responsive and 16 with treatment-resistant Lyme arthritis. RESULTS: The maximum severity of joint swelling correlated directly with the response to OspA. Moreover, the only significant difference between patients with treatment-resistant and treatment-responsive arthritis was in reactivity with N-terminal and C-terminal fragments of OspA, OspA1 (amino acids [aa] 16-106), and OspA3 (aa 168-273). Epitope mapping showed that 14 of the 16 patients with treatment-resistant arthritis had responses to OspA peptides (usually 4 or 5 epitopes), whereas only 5 of the 16 patients with treatment-responsive arthritis had reactivity with these peptides (usually 1 or 2 epitopes) (P = 0.003). Patients with HLA-DRB1 alleles associated with treatment-resistant arthritis were more likely to react with peptide 15 (aa 154-173) and, to a lesser degree, with peptide 21 (aa 214-233) than patients with other alleles, whereas the responses to other epitopes were similar in both groups. CONCLUSION: The maximum severity of joint swelling and the duration of Lyme arthritis after antibiotic treatment are associated with T cell responses to specific epitopes of OspA.
Assuntos
Antígenos de Superfície/imunologia , Proteínas da Membrana Bacteriana Externa/imunologia , Resistência Microbiana a Medicamentos/imunologia , Lipoproteínas , Doença de Lyme/tratamento farmacológico , Doença de Lyme/imunologia , Adolescente , Adulto , Idoso , Alelos , Antibacterianos/uso terapêutico , Formação de Anticorpos , Vacinas Bacterianas/imunologia , Grupo Borrelia Burgdorferi , Criança , Doxiciclina/uso terapêutico , Mapeamento de Epitopos , Epitopos de Linfócito T/efeitos dos fármacos , Feminino , Antígenos HLA/genética , Humanos , Epitopos Imunodominantes/imunologia , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Linfócitos T/imunologia , Resistência a Tetraciclina/imunologia , Fatores de TempoRESUMO
The effects of mutations in host genes on tetracycline resistance mediated by the Tet(O) and Tet(M) ribosomal protection proteins, which originated in Campylobacter spp. and Streptococcus spp., respectively, were investigated by using mutants of Salmonella typhimurium and Escherichia coli. The miaA, miaB, and miaAB double mutants of S. typhimurium specify enzymes for tRNA modification at the adenosine at position 37, adjacent to the anticodon in tRNA. In S. typhimurium, this involves biosynthesis of N6-(4-hydroxyisopentenyl)-2-methylthio-adenosine (ms2io6A). The miaA mutation reduced the level of tetracycline resistance mediated by both Tet(O) and Tet(M), but the latter showed a greater effect, which was ascribed to the isopentenyl (i6) group or to a combination of the methylthioadenosine (ms2) and i6 groups but not to the ms2 group alone (specified by miaB). In addition, mutations in E. coli rpsL genes, generating both streptomycin-resistant and streptomycin-dependent strains, were also shown to reduce the level of tetracycline resistance mediated by Tet(O) and Tet(M). The single-site amino acid substitutions present in the rpsL mutations were pleiotropic in their effects on tetracycline MICs. These mutants affect translational accuracy and kinetics and suggest that Tet(O) and Tet(M) binding to the ribosome may be reduced or slowed in the E. coli rpsL mutants in which the S12 protein is altered. Data from both the miaA and rpsL mutant studies indicate a possible link between stability of the aminoacyl-tRNA in the ribosomal acceptor site and tetracycline resistance mediated by the ribosomal protection proteins.