ABSTRACT
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.
Subject(s)
DNA, Bacterial/analysis , Mycoplasma pneumoniae/isolation & purification , Pneumonia, Mycoplasma/diagnosis , Polymerase Chain Reaction , DNA, Bacterial/isolation & purification , Humans , Mycoplasma pneumoniae/genetics , Pharynx/microbiology , Predictive Value of Tests , Respiratory System/microbiology , Sensitivity and SpecificitySubject(s)
Bacterial Proteins , Carrier Proteins , Hexosyltransferases/analysis , Latex Fixation Tests , Methicillin Resistance , Multienzyme Complexes/analysis , Muramoylpentapeptide Carboxypeptidase , Peptidyl Transferases/analysis , Staphylococcal Infections/microbiology , Staphylococcus aureus/drug effects , Bacteriological Techniques , Coagulase/metabolism , Humans , Methicillin Resistance/genetics , Penicillin-Binding Proteins , Staphylococcus aureus/isolation & purificationABSTRACT
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.
Subject(s)
Bites and Stings/complications , Fishes , Gram-Negative Bacterial Infections/microbiology , Halomonas/isolation & purification , Wound Infection/microbiology , Animals , Female , Gram-Negative Bacterial Infections/diagnosis , Halomonas/genetics , Humans , Middle Aged , Seawater , Wound Infection/diagnosisABSTRACT
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.
