TABLE 2

Multicenter/multiregion CF studies assessing the prevalence of clonal Pseudomonas aeruginosa strainsa

Country or regionNo. of centers% of populationFocusTime period (yr)Testing modality(ies)Cohort size (no. of subjects)Main finding(s)Reference(s)
Australia4NSPeds1999–2006ERIC-PCR and PFGE82A subset of the Australasian CF BAL study revealed that all but 3 children (without prior P. aeruginosa infection) experienced new incident infection with novel isolates56, 57
1890All2007–2010ERIC-PCR and PFGE98319 clones infecting ≥3 patients were identified in the national ACPinCF study; AUST-01 (22%) and AUST-02 (18%) were most prevalent, found in 89% and 94% of centers, respectively; other common strains were AUST-04 (5%), AUST-05 (4%), AUST-06 (3%), and AUST-07 (2%); only AUST-05 has been observed commonly in the natural environmentb; clonal strains were observed disproportionally in older patients, suggesting that infection control policies have been successful in reducing transmissionc96, 97
Brazil4NSAll2009–2010PFGE752 of the 4 clinics had several pairings of unrelated patients with shared strains, representing <20% of each clinic; no shared clones were identified between clinics; no established ePA strains were identified289
Belgium7100All2003–2004RAPD-PCR and then fAFLP27613 clusters of unrelated patients with clonal isolates were identified, including between 2 and 12 patients each; 10 of these clusters could be linked to attendees of the Zeepreventorium; patients in clusters had higher association scores than those with nonclonal isolates; no UK ePA clonal strains were identified61
Canada8 (Ontario)NSAdults (≥16 yr of age)2001–2003PFGE36In this study, which sought to identify new strains of P. aeruginosa during pulmonary exacerbations, researchers observed 33% of patients to be infected with a single clone (strain A; LES)290
7 (Ontario)NSAdults2003–2005PFGE and MLST446Patients were prospectively monitored with quarterly sputum cultures for 3 yr; strain A (LES) and strain B were identified in 22% and 11% of individuals, respectively (each found in 6 of the 7 clinics); 7 new incident infections were observed during the study period71, 186, 228
7NSAll2011–2014MLST483High genetic diversity among colonizing strains was observed; rates of ePA were low, with LES and PES observed at 2% and 4% prevalences, respectively; the most common clone was clone C, in 11% of individuals281
France10NSAll2006–2007VNTR analysis and MLVA156In representative samples from multiple clinics, modest clusters of P. aeruginosa spread among the 10 clinics were identified, but no clone exceeded infection in ≥3 patients/center; established ePA strains were not identified291
International39NSNSNSCustom multilocus microarray133CF isolates were compared against a very large collection of environmental and non-CF clinical isolates; 13 clones represented half of all strains and included environmentally ubiquitous isolates PA14, clone C, and CHA; using a subset of targets within the accessory genome, researchers were able to determine that the vast majority of isolates were indeed different and therefore independently acquired222
Italy3NSNS2006–2008AT typing, PFGE, and MLST124The focus of the study was not on identifying clonal strains, but those researchers identified 7 ST260 isolates from a single center, although these isolates fell into 2 AT types and 5 pulsotypes, suggesting that these isolates were not closely related; indeed, MLST ST260 isolates are commonly found in natural environmentsd153
Netherlands246All2007–2008MLST313142 different STs were identified as causing infection; in particular, ST406 was found in 15% of subjects, and ST497 was found in 5%; other less common STs identified were ST274 (3%), ST108 and -155 (2% each), ST17, -492, -511, -27, -170, -395, and -517 (2% each), and ST111, -261, -267, -485, -540, and -561 (1% each)81
2NSAll2007–2011MLSTAfter universal segregation was introduced, no significant changes in prevalences of STs were observed, and 3 cases of ST406 superinfection were observed80
New Zealand775All2004–2005PFGE269A heterogeneous P. aeruginosa population was observed, although several small clusters were apparent; the largest cluster involved 9 patients (18% prevalence in one center); patients with this strain were determined to have a higher degree of contact, supporting its potential for transmission; other smaller clusters were present in 6, 5, 4, and 3 individuals; cases of AUST-02 (4 cases), AUST-01 (1 case), and MA (1 case) infections were identified, generally with epidemiological links to zones of endemicity60
Norway326All1994–1998PFGE60A single pulsotype was observed to infect 45% of individuals, and several smaller clusters (2–4 individuals) were identified; infection with the dominant clone was associated with CF camps, health-related CF training camps, and attendance at one particular regional hospital59
Spain2410All2013–2014MLST, AT marker analysis, and microarray75A highly heterogeneous P. aeruginosa population was observed; in this limited sampling of individuals from any individual clinic, shared clones were rare; in fact, only one nonkindred pairing was identified; established ePA strains were not observed226
United Kingdom (England and Wales)3120All2002–2003fAFLP and PFGE849Importantly, 72% of patients harbored unique isolates; LES was widespread, accounting for 11% of all isolates (found in 48% of centers); less common isolates included Mid-1 (10%), clone C (2%), MA (1%), and Trent (1%); with the exception of LES, most ePA strains were concentrated in a specific center111
  • a ePA, epidemic P. aeruginosa; Peds, pediatric CF patients; adults, adult CF patients; All, both adult and pediatric CF patients; NS, not stated; fAFLP, fluorescent amplified fragment length polymorphism analysis; AT, ArrayTube.

  • b See reference 41.

  • c See references 42 and 57.

  • d See references 292 and 293.