EPIDEMIOLOGY OF PSEUDOMONAS AERUGINOSA INFECTION IN PATIENTS TREATED AT A CYSTIC FIBROSIS CENTRE

Abstract

P. aeruginosa isolates (484) were obtained from the respiratory tract of 45 of 70 cystic fibrosis (CF) patients at monthly examinations during 1 yr at the Danish CF Center. All isolates were serogrouped (O-antigens) and phage-typed and in this way 99% of the isolates could be grouped and/or typed. The isolates from CF patients belonged to many different serogroups; 55% were polyagglutinable and most of these belonged to the 0-3/9 complex. This was significantly different from the O-group distribution of isolates from non-CF patients. The results of the combined phage-typing and serogrouping revealed the occurrence of 13 clusters of distinct epidemiological types of P. aeruginosa among small groups (2-10 individuals) of CF patients. The predominating endemic strain, isolated from 10 (22%) of the patients, belonged to the 0-3/9 complex and was lysed by phage 109 alone or in combination with a few other phages. In a few cases the eradication of another strain of P. aeruginosa by chemotherapy was followed by colonization of the lungs with this predominating strain which was associated with high mortality. Measures should be undertaken to identify and eliminate routes of cross-infection in CF centers to diminish the prevalence of P. aeruginosa infection and thereby reduce the mortality of CF patients.