Clonal strains ofPseudomonas aeruginosain paediatric and adult cystic fibrosis units

Abstract

Despite recent reports of clonal strains of Pseudomonas aeruginosa in cystic fibrosis (CF) units, the need for routine microbiological surveillance remains contentious.Sputum was collected prospectively from productive patients attending the regional paediatric and adult CF units in Brisbane, Australia. All P. aeruginosa isolates were typed using pulsed-field gel electrophoresis. Spirometry, anthropometrics, hospitalisations and antibiotic sensitivity data were recorded.The first 100 sputum samples (first 50 patients at each clinic) harboured 163 isolates of P. aeruginosa. A total of 39 patients shared a common strain (pulsotype 2), 20 patients shared a strain with at least one other patient and 41 patients harboured unique strains. Eight patients shared a strain identical to a previously reported Australian transmissible strain (pulsotype 1). Compared with the unique strain group, patients harbouring pulsotype 2 were younger and had poorer lung function. Treatment requirements were similar in these two groups, as were the rates of multiresistance.In conclusion, 59% of patients harboured a clonal strain, supporting the need for routine microbiological surveillance. In contrast to previously described clonal strains, the dominant pulsotype was indistinguishable from nonclonal strains with respect to both colonial morphology and multiresistance. The clinical significance of clonal strains remains uncertain and requires longitudinal study.

Factors associated with infection byPseudomonas aeruginosain adult cystic fibrosis

“…However, multiple reports from the UK, Australia and Norway suggest that cross-infection between unrelated patients occurs much more frequently than previously recognised [3][4][5][6][7]10]. In keeping with the current findings, the studies from Liverpool, Melbourne, Brisbane and Bergen all found that the majority of P. aeruginosa-infected patients attending their centres harboured clonal isolates.…”

“…Although cross-infection with P. aeruginosa in siblings with CF is well documented [2], crossinfection in other settings has been thought to be rare. There is now increasing evidence of the importance of cross-infection in paediatric [3,4] and, more recently, adult [4][5][6][7] CF centres. There is naturally concern among patients, families and carers that this spread may adversely impact upon morbidity and mortality.…”

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

“…51 Other reports described shared or epidemic P. aeruginosa strains in the United Kingdom and Australia. 53,[179][180][181] PFGE analysis of 1,225 P. aeruginosa isolates recovered from people with CF receiving care in 31 treatment centers in the United Kingdom demonstrated that 28% of those infected harbored a strain shared with at least 1 other person with CF. 173 The 2 most prevalent strains accounted for more than 20% of the isolates examined.…”

“…Strain differences in the production of infectious droplets or droplet nuclei that remain suspended in the air under experimental conditions may explain the differences in efficiency of transmission of epidemic P. aeruginosa strains. 119 Infections with a shared strain 130,173,179 are highly suggestive of patient-to-patient transmission, particularly as institution of IP&C measures halted transmission. 30,185 While acquisition from a common source is also a possibility, surveillance of inpatient and outpatient settings have not detected a reservoir for shared strains.…”

“…180 This strain, now referred to as the Australian epidemic strain 1 (AES-1), has also been identified in Brisbane. 179 The Australian epidemic strain 2 (AES-2) is even more common in Brisbane, 182 while the Australian epidemic strain 3 (AES-3) is common in Tasmania. 183 In Copenhagen, Denmark, PFGE and genomic DNA sequence analyses identified 2 major P. aeruginosa clones that have been common among and likely transmitted among people with CF for more than 2 decades.…”