Background: To determine the rate of pertussis in infants aged <1 year hospitalized at the pediatric intensive care unit (PICU) with lower respiratory tract infection (LRTI) and to characterize the clinical aspects of these patients.
Material/Methods: Infants <12 months hospitalized with LRTI in the PICU were identified retrospectively. Demographic, clinical and laboratory data were obtained. Stored nasopharyngeal washes (NPW) were tested by polymerase chain reaction (PCR) for the pertussis toxin gene (ptxA) and insertion element IS481 sequences.
Results: Eleven of seventy-four (15%) NPW were positive for pertussis, none of them was clinically suspected. Of the positive patients, 82% suffered from paroxysmal cough vs. 32% of the negative patients and from prolonged cough, 45.5% vs. 8%, respectively (P<0.01). Thirty (41%) patients needed mechanical ventilation with no differences between positive and negative pertussis patients. Infiltrates in x-rays were more common among pertussis negative than among pertussis positive patients, 29% vs. 0% (P=0.05).
Conclusions: Lower respiratory tract infections caused by pertussis are a more frequent cause of admission to the PICU than generally recognized. Patient’s history with paroxysmal cough suggests the possibility of pertussis and the lack of whooping cough does not rule out pertussis. Pediatricians should be aware of the limitations of their diagnostic tools when ruling out pertussis especially in infants with a diagnosis of bronchiolitis. Using new diagnostic methods add considerably to the sensitivity of pertussis diagnosis in PICU and PCR techniques should be used routinely, at least in a PICU setting.

Keywords: Diagnostic Errors, Polymerase Chain Reaction, Whooping Cough - microbiology, Bordetella pertussis - genetics, Diagnosis, Differential, Infant, Newborn, Intensive Care Units, Neonatal, Intensive Care Units, Pediatric, Israel, Polymerase Chain Reaction, Respiratory Tract Infections - diagnosis