Should the pertussis case definition for public health reporting be refined?

BACKGROUND: The surveillance case definition for confirmed pertussis requires that an individual with a positive polymerase chain reaction (PCR) result for Bordetella pertussis have 2 weeks or more of cough and at least one of the following: paroxysmal coughing, inspiratory "whoop," or posttussive vomiting. OBJECTIVES: Determine (1) proportion of individuals with a positive PCR result who met additional criteria for surveillance confirmed pertussis, (2) whether the likelihood of PCR-positive individuals meeting additional elements of surveillance case definition varied by age or vaccination status, and (3) whether elements of the current case definition influence the likelihood of pertussis confirmation in PCR-positive individuals. METHODS: Pertussis PCR results were compared with case investigation data. RESULTS: Eighty-eight percent (165/188) of PCR-positive individuals met requirements for confirmed pertussis. Sixty-one percent (14/23) of PCR-positive individuals who had less than 2 weeks but more than 1 week of cough had at least one other reported sign or symptom. Fourteen (100%) reported paroxysmal coughing, 7 (50%) "whoop," and 7 (50%) posttussive vomiting. Infants who met case definition were more likely to have reported apnea than were older individuals (15/17 vs 45/86, OR = 6.8, 95% CI = 1.4-64.2). CONCLUSIONS: Decreasing cough duration from 2 weeks or more to more than 1 week would result in 95 percent of those with positive PCR results meeting confirmation criteria for pertussis. Apnea should be considered an additional sign for pertussis confirmation in infants.

Specimen type as a source of variability in the reproducibility and timing of cytomegalovirus identification by culture.

Cytomegalovirus (CMV) is a significant contributor to morbidity and mortality among immunocompromised individuals; therefore, rapid and accurate diagnosis is essential. We compared positive cultures (n = 147) from different specimen types as to (a) the incubation time to a positive result and (b) the reproducibility of positive findings in replicate cultures. Five replicate shell vials were inoculated from each specimen: Two vials were stained at 24 h, two at 48 h, and one held and observed for a maximum of 30 days. Positive cultures from tissue biopsy specimens required the shortest incubation (mean = 1.9 days) and urine specimens the longest (mean = 3.9 days) (P < .005). Tissue biopsy specimens were the most reproducible (48.4% of specimens were positive in five of five replicates) and urine specimens the least (no specimens were positive in five of five replicate vials) (P < = .0002). The observed interspecimen variability is important because failure to understand and adjust for these differences could negatively influence the ability to identify CMV in culture.

Optimal recovery of cytomegalovirus from urine as a function of specimen preparation.

Cytomegalovirus (CMV) is a significant pathogen among immunocompromised patients. We compared supernatant and sediment fractions of centrifuged urine for the optimal recovery of CMV by shell vial culture and polymerase chain reaction (PCR). Of 336 urine specimens, 31 (9.23%) were positive by shell vial culture; of these 29 (93.5%) were identified using the sediment fraction and 17 (54.8%) using the supernatant fraction (p = 0.001, chi2). Of the 29 positive sediment fraction specimens, 24 (82.8%) were identified as CMV positive at 24 h and 5 (17.2%) were identified as positive at 48 h. Two (0.064%) of the total 31 positive specimens were lost to microbial contamination in the sediment inoculated cultures. Of the 17 supernatant fraction specimens, 9 (53.9%) were identified as CMV positive at 24 h and 8 (47.1%) were identified as positive at 48 h. Fourteen (45.2%) of the total 31 positive specimens were lost to either toxicity or microbial contamination in the sediment-inoculated cultures. Thirty-four CMV culture-positive specimens were tested by PCR; 5 of these specimens (14.7%) were PCR negative for both sediment and supernatant fractions; 26 (76.5%) were found to be positive using the sediment fraction and negative using the supernatant; 3 (8.8%) were PCR positive for both the sediment and the supernatant. None of the 34 was identified as positive using the supernatant fraction only (p = 0.001, chi2). These findings demonstrate that the method of specimen preparation can significantly affect the outcome of diagnostic testing for CMV from urine specimens.

Cytomegalovirus induction of interleukin-6 in lung fibroblasts occurs independently of active infection and involves a G protein and the transcription factor, NF-kappaB.

Cytomegalovirus (CMV) infection induces the proinflammatory cytokine, interleukin (IL)-6, which may contribute to the pathology of the infection. In vitro CMV induction of IL-6 by human lung fibroblasts was studied. The quantity of cytokine in culture supernatants was maximal 20 h after infection and decreased thereafter. Transcription of the IL-6 gene and IL-6 protein expression were equally stimulated by infectious and UV-inactivated virus (CMV-UV). CMV-UV-stimulated IL-6 was inhibited by pyrrolidinedithiocarbamate (an inhibitor of the transcription factor, NF-kappaB) and by pertussis toxin (suggesting the involvement of a G protein) and occurred in the absence of CMV immediate-early antigen transcription. Neutralizing antibodies to IL-1beta or tumor necrosis factor-alpha did not affect CMV-UV-induced IL-6, but expression was inhibited by antibody to the CMV attachment glycoprotein. IL-6 production by fibroblasts occurs independently from productive infection but has characteristics that suggest a ligand receptor-mediated pathway. This function may be important in pathology or disease resolution.