ACQUISITION OF PSEUDOMONAS-CEPACIA AT SUMMER CAMPS FOR PATIENTS WITH CYSTIC-FIBROSIS

To assess the risk of acquisition of Pseudomonas cepacia by person-to- person transmission at cystic fibrosis summer camps, we conducted in 1 990 a study at three camps attended by patients with cystic fibrosis w ho had P. cepacia infection and patients without P. cepacia infection but who were considered susceptible to infection. We obtained sputum o r throat cultures from campers on their arrival at, weekly during, at the end of, and 14 to 30 days after camp. We compared the incidence of sputum conversion of patients at camp with that of patients outside c amp by culturing specimens from noncamper control subjects with cystic fibrosis who were known not to be infected less than or equal to 2 we eks before and 4 to 6 weeks after camp. We also determined the risk fa ctors for P. cepacia acquisition by determining the relative risk of a cquisition between campers who were exposed versus campers who were no t exposed to campers known to be infected or to potential environmenta l sources of P. cepacia at camp. The ribotype of P. cepacia isolates f rom campers with sputum conversion was compared with that of isolates from other campers and from an environmental source. The cumulative in cidence of sputum conversion during the study period was 6.1% (11/181) among campers compared with no incidence (0/92) among noncampers (p = 0.02, Fisher Exact Test). The incidence of sputum conversion at camp varied according to the prevalence of campers with known infection (p <0.001, chi-square test for trend). The rate of sputum conversion was higher in the camp with longer duration (relative risk = 12.0; 95% con fidence interval = 2.7 to 53.5). Ribotyping showed that P. cepacia iso lates from all 11 campers with sputum conversion were identical or sim ilar (1 to 2 band difference) to isolates of other P. cepacia-infected campers including co-converters. These results suggest that P. cepaci a can be acquired by patients with cystic fibrosis who are attending s ummer camp for such patients, possibly through person-to-person transm ission, and that the risk increases with the prevalence of P. cepacia- infected campers and the duration of camp.