RESUMO
A panel of 78 respiratory samples collected from 43 patients was analyzed in three different Centers for the presence of Mycoplasma pneumoniae DNA by polymerase chain reaction (PCR). One Center collected the samples and extracted the DNA by two different methods. DNA extracted according to the first method was amplified using primers targetting the 16 S rRNA gene. DNA extracted according to the second method was amplified using the same primers in a semi-nested format and was sent to the two other Centers. The latter Centers both used the same primers targetting the P1 gene but with a different detection format. Thirty-nine samples (50%) from 19 patients were positive by at least two PCR assays. None of the laboratories were free of false positive or false negative PCR results. Calculated specificities of the individual PCR assays ranged from 97.4% to 87.2% and sensitivities ranged from 97.4% to 89.2%. Complement fixation was done on sera of 33 patients. The calculated specificity and sensitivity of serology was 100% and 58.8%, respectively. Several aspects concerning false positive and false negative results with PCR are discussed.
Assuntos
DNA Bacteriano/análise , Mycoplasma pneumoniae/isolamento & purificação , Pneumonia por Mycoplasma/diagnóstico , Reação em Cadeia da Polimerase , DNA Bacteriano/isolamento & purificação , Humanos , Mycoplasma pneumoniae/genética , Faringe/microbiologia , Valor Preditivo dos Testes , Sistema Respiratório/microbiologia , Sensibilidade e EspecificidadeAssuntos
Proteínas de Bactérias , Proteínas de Transporte , Hexosiltransferases/análise , Testes de Fixação do Látex , Resistência a Meticilina , Complexos Multienzimáticos/análise , Muramilpentapeptídeo Carboxipeptidase , Peptidil Transferases/análise , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Técnicas Bacteriológicas , Coagulase/metabolismo , Humanos , Resistência a Meticilina/genética , Proteínas de Ligação às Penicilinas , Staphylococcus aureus/isolamento & purificaçãoRESUMO
Halomonas venusta, a moderately halophilic, nonfermentative gram-negative rod, is reported for the first time as a human pathogen in a wound that originated from a fish bite.
Assuntos
Mordeduras e Picadas/complicações , Peixes , Infecções por Bactérias Gram-Negativas/microbiologia , Halomonas/isolamento & purificação , Infecção dos Ferimentos/microbiologia , Animais , Feminino , Infecções por Bactérias Gram-Negativas/diagnóstico , Halomonas/genética , Humanos , Pessoa de Meia-Idade , Água do Mar , Infecção dos Ferimentos/diagnósticoRESUMO
In diagnostic amplification protocols contamination by previously amplified nucleic acids is considered the major source of false positive results. Substituting dUTP for dTTP in the PCR and initial treatment with uracil-DNA glycosylase (UNG) virtually eliminates these carryover contaminations. Subsequent procedures to visualize the amplicons or to optimize sensitivity and specificity of the test are not always fully compatible with UNG-treated PCR products. Here we describe the more pronounced influence of residual UNG activity on the migration of PCR amplification products in polyacrylamide as compared to agarose gels.
