Molecular typing and epidemiological investigation of clinical populations of <it>Pseudomonas aeruginosa</it> using an oligonucleotide-microarray

• Main Authors: Ballarini Annalisa, Scalet Giovanna, Kos Malgorzata, Cramer Nina, Wiehlmann Lutz, Jousson Olivier
• Format: Article
• Language: English
• Published: BMC 2012-07-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/12/152

<p>Abstract</p> <p>Background</p> <p><it>Pseudomonas aeruginosa</it> is an opportunistic pathogen which has the potential to become extremely harmful in the nosocomial environment, especially for cystic fibrosis (CF) patients, who are easily affected by chronic lung infections. For epidemiological purposes, discriminating <it>P.aeruginosa</it> isolates is a critical step, to define distribution of clones among hospital departments, to predict occurring microevolution events and to correlate clones to their source. A collection of 182 <it>P. aeruginosa</it> clinical strains isolated within Italian hospitals from patients with chronic infections, i.e. cystic fibrosis (CF) patients, and with acute infections were genotyped. Molecular typing was performed with the ArrayTube (AT) multimarker microarray (Alere Technologies GmbH, Jena, Germany), a cost-effective, time-saving and standardized method, which addresses genes from both the core and accessory <it>P.aeruginosa</it> genome. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were employed as reference genotyping techniques to estimate the ArrayTube resolution power.</p> <p>Results</p> <p>41 AT-genotypes were identified within our collection, among which 14 were novel and 27 had been previously described in publicly available AT-databases. Almost 30% of the genotypes belonged to a main cluster of clones. 4B9A, EC2A, 3C2A were mostly associated to CF-patients whereas F469, 2C1A, 6C22 to non CF. An investigation on co-infections events revealed that almost 40% of CF patients were colonized by more than one genotype, whereas less than 4% were observed in non CF patients. The presence of the <it>exoU</it> gene correlated with non-CF patients within the intensive care unit (ICU) whereas the pKLC102-like island appeared to be prevalent in the CF centre. The congruence between the ArrayTube typing and PFGE or MLST was 0.077 and 0.559 (Adjusted Rand coefficient), respectively.</p> <p>AT typing of this Italian collection could be easily integrated with the global <it>P. aeruginosa</it> AT-typed population, uncovering that most AT-genotypes identified (> 80%) belonged to two large clonal clusters, and included 12 among the most abundant clones of the global population.</p> <p>Conclusions</p> <p>The ArrayTube (AT) multimarker array represented a robust and portable alternative to reference techniques for performing <it>P. aeruginosa</it> molecular typing, and allowed us to draw conclusions especially suitable for epidemiologists on an Italian clinical collection from chronic and acute infections.</p>