A Comparison of Laboratory and Clinical Methods for Diagnosing Pertussis in an Outbreak in a Facility for the Developmentally Disabled

Abstract

During a pertussis outbreak in a facility for the developmentally disabled, culture- or direct fluorescent-antibody-confirmed cases were identified in 24 residents and 17 staff members; 38 (93%) were culture positive for Bordetella pertussis. An enzyme-linked immunosorbent assay (ELISA) was used to detect serum IgG and IgA to the filamentous hemagglutinin and lymphocytosis-promoting factor of B. pertussis. Using criteria from ELISA values, we identified an additional 83 residents and 28 staff members as seropositive. Among seropositive persons, antibody levels were elevated by the time of onset of respiratory symptoms and, in three of the four assays, remained elevated for 14 mo. In 44 seropositive persons tested within two weeks of onset of symptoms, 80% were culture positive, compared with 33% of 15 tested two to four weeks after onset (P = .003) and none of 15 tested more than four weeks after onset. The most specific (94%) clinical case definition identified only 41% of seropositive persons. Thus, ELISAs are important tools for individual diagnosis and epidemiological studies of pertussis.

Molecular Pathogenesis, Epidemiology, and Clinical Manifestations of Respiratory Infections Due toBordetella pertussisand OtherBordetellaSubspecies

“…A specific medium for the culture of B. pertussis was described in 1906 (63), and the demonstration of serum agglutinating antibody for diagnosis was noted in 1916 (635). In the present era, the extensive acellular pertussis vaccine efficacy trials and other epidemiological studies have made it possible to evaluate multiple methods for the laboratory diagnosis of B. pertussis infections (229,293,310,315,317,337,493,536,693,719,722,740,781). Common laboratory diagnostic methods currently include culture, direct antigen detection (direct fluorescent-antibody [DFA] test) PCR, and serologic demonstration (ELISA with many B. pertussis antigens and agglutination) by measuring rises in titer or high single serum values.…”

Recent progress in clinical and basic pertussis research

“…In the case of pertussis, avoidance of exposure is unrealistic since transmission is highest early in the illness and frequently occurs before a diagnosis has been made in the index case [24]. Prophylactic chemotherapy, primarily by use of erythromycin for 14 days in therapeutic dosage, has been demonstrated to be ecacious [36,130] when given to close contacts, especially if administered before secondary cases have occurred [125]. Whether chemoprophylaxis should be recommended to completely immunised (!)…”

Mixture model analysis for establishing a diagnostic cut-off point for pertussis antibody levels

“…unexposed persons, healthy volunteers, blood donors) to help diagnose pertussis in numerous pertussis studies [42]. Another method deÿned the cut-o point as the maximum observed value in the control group to ensure maximum speciÿcity [43]. These traditional approaches to deriving diagnostic cut-o values are unsatisfactory for several reasons.…”