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A major outbreak of 5,683 cases of pertussis occurred in northern Alberta, Canada, from December 1989 to January 1991. The outbreak highlighted a number of problems with current methods of pertussis diagnosis.In particular, an exceptionally high proportion of direct fluorescent-antibody (DFA)-positive, culture-negative specimens (88.4%) was identified. We took this opportunity to use polymerase chain reaction (PCR) methodology to examine whether the low culture rates were due to specimens containing dead organisms or whether the DFA results represented high numbers of false-positive results. A set of primer sequences within a Bordetella pertussis-specific repetitive element was used to amplify proteinase K extracts of B. pertussis DNA recovered from 279 submitted slides inoculated at the point of collection with nasopharyngeal material obtained from pernasal swabs. The PCR data corroborated the culture results: 84.6% of DFA-positive, culture-negative specimens were similarly PCR negative. At least three different bacterial species that were significantly cross-reactive with the commercial DFA reagent were identified in clinical specimens and in pure culture, providing one possible explanation for the false-positive DFA results. These results and other limitations of current diagnostic techniques underline the urgent need for a new DFA reagent with improved specificity and a standardized means of measuring the patient antibody response for the diagnosis of pertussis.Whooping cough (pertussis) may be 10 to 40 times more prevalent than passive reporting systems indicate (46). The true incidence of disease could be better determined if the means of diagnosing the disease was improved in North America (15,17,23,39). For one, the case definition of pertussis varies among different state and provincial health departments (8,15,27,42,46), which complicates reporting. For another, diagnosis itself is dramatically influenced by the time in the course of their disease that patients are seen. The clinical symptoms of pertussis are typically not unique early in the catarrhal stage (21,38,45) and the classic paroxysmal coughing that occurs later in the course of the disease may be absent, depending on the age of the patient, the patient's immune status, and whether the patient was treated with antibiotics (2,4,29,35,44).Laboratory diagnosis of pertussis is similarly affected by the same factors that influence symptomatology. Culture and fluorescent-antibody detection of organisms in nasopharyngeal swabs or aspirates are more likely to be positive just before or early after the onset of symptoms but are increasingly less likely to be positive as time elapses after the onset of cough (38,45,47). Conversely, serological tests, which are dependent on the new synthesis of pertussis-specific antibody in the patient, are more likely to be positive only after symptoms begin (29,32,45).In the province of Alberta, the case definition of pertussis is (i) characteristic paroxysmal cough, cough episodes ending in apnea, vomiting, or inspir...

The published nucleotide sequences of the 16S rRNA gene of Haemophilus ducreyi were used to develop primer sets and probes for the diagnosis of chancroid by polymerase chain reaction (PCR) DNA amplification. One set of broad specificity primers yielded a 303-bp PCR product from all bacteria tested. Two 16-base probes internal to this sequence were species specific for H. ducreyi when tested with 12 species of the families PasteureUaceae and Enterobacteriaceae. The two probes in combination with the broad specificity primers were 100% sensitive with 51 strains of H. ducreyi isolated from six continents over a 15-year period. The direct detection of H. ducreyi from 100 clinical specimens by PCR showed a sensitivity of 83 to 98% and a specificity of 51 to 67%, depending on the number of amplification cycles.

MARUSYK, R. G., and T. YAMAMOTO. 1971. Characterization of a canine adenovirus hemagglutinin.Can. J. Microbial. 17: 151-155. The hemagglutinating activity of the canine adenoviruses was found to be more than 80y0 associated with both the intact and incomplete ('empty') virus particles, the remaining complete hemagglutinating activity being associated with a naturally occurring soluble penton dinier structure. Trypsin treatment of the heniagglutinin -red blood cell coniplex and receptor-competition experiments, using purified fiber component to block the receptor sites on the red blood cells, indicate that there are different receptors for infectious canine laryngotracheitis (ICL) virus and infectious canine hepatitis (ICH) virus.The ICL adenovirus was found to heniagglutinate human and rat erythrocytes but not those of a number of other animal species. Using human group '0' erythrocytes the ICL virus associated heniagglutinating activity was found to occur over a wide range in temperature and pH, and certain purification procedures, such as fluorocarbon treatment and sonic oscillation, were found to inactivate the hemagglutinin rapidly.