[Protracted croup syndrome. Bacteriologic findings and therapeutic consequences].

Background: Croup normally is characterized by acute onset and a self limited course of only few days. In 1990 and 1991 at the University Children's Hospital Freiburg an unexpected high number of patients were hospitalized for prolonged Croup syndrome. Expanded microbiological investigations were used to uncover etiologic factors.
Methods: Of a total of 138 inpatients with Croup 60 (17 in their first year of life, 21 in the second year of life and 22 infants older than 2 years) had bacteriological (37 nasopharyngeal-, 4 tracheal-aspirates or 19 throat swabs), and virological (antigen detection in nasopharyngeal aspirates, n = 28) tests. Of these patients 48% were hospitalized longer than 3 days (mean 4,7; range 1-18 days).
Results: Bacteria found: B. catarrhalis 24/11 (total/pure-culture), S. pneumoniae 15/6, H. influenzae 10/3, S. group A 5/4 and S. aureus 4/1. Sixteen specimen yielded more than one pathogen, one specimen was sterile. Nasopharyngeal secretions had the most reliable results: Pure cultures (72%) and associations of two pathogens (87%) were found in these aspirates, and only 26% of the unspecific mixed findings (p < 0.005; chi 2-Test). Of the patients hospitalized longer than 3 days 27.6% had positive cultures for H. influenzae, whereas only 6.5% of those hospitalized shorter (p < 0.05; chi 2-Test). The only microorganism with an age-bound distribution was B. catarrhalis found predominantly (54.2%) in the 2nd year of life, with 62% of patients positive (p < 0.05; chi 2-Test). Virus found: RSV (n = 3), Parainfluenza 2 (1) and Parainfluenza 3 (1).
Conclusions: Nasopharyngeal aspirate is the most reliable specimen for a bacteriologic diagnosis in Croup. In the second year of life B. catarrhalis is present in most Croup cases, and H. influenzae was associated with a prolonged course of the disease. An appropriate antibiotic therapy therefore must cover these two pathogens.