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Genotypic and phenotypic relatedness of Pseudomonas aeruginosa isolates among the major cystic fibrosis patient cohort in Italy.

Cigana C, Melotti P, Baldan R, Pedretti E, Pintani E, Iansa P, De Fino I, Favari F, Bergamini G, Tridello G, Cirillo DM, Assael BM, Bragonzi A - BMC Microbiol. (2016)

Bottom Line: Here, we look at the major CF patient cohort in Italy to identify shared P. aeruginosa clones and associated common phenotypic traits.No clear correlation between epidemiological and clinical data was found.We conclude that CF patients of this cohort shared common pulsotypes, but their phenotypic heterogeneity indicates an absence of specific traits associated to P. aeruginosa genotypic prevalence.

View Article: PubMed Central - PubMed

Affiliation: Infections and Cystic Fibrosis Unit, Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, via Olgettina 58, 20132, Milan, Italy. cigana.cristina@hsr.it.

ABSTRACT

Background: Pseudomonas aeruginosa is the predominant pathogen associated with the decline of pulmonary function in cystic fibrosis (CF) patients. Both environment-to-host acquisition and patient-to-patient transmission have been described for P. aeruginosa infection. Epidemic clones and bacterial phenotypic adaptation to the CF lung have been recognised as independent risk factors for disease progression. So far, there is no established link between genotypic prevalence and phenotypic traits. Here, we look at the major CF patient cohort in Italy to identify shared P. aeruginosa clones and associated common phenotypic traits.

Results: A comprehensive analysis of P. aeruginosa genotypes to determine the presence of high-risk shared clones and their association to specific phenotypic traits has been performed in a major Italian CF centre. Pulsed-field gel electrophoresis (PFGE) of P. aeruginosa isolates from 338 CF subjects identified 43 profiles shared by two or more patients and 214 profiles exclusive to individual patients. There was no evidence of a P. aeruginosa outbreak, but four most prevalent pulsotypes were detected. Common phenotypic traits were recorded intra-pulsotypes, but we detected heterogeneity inter-pulsotypes. Two of the four major pulsotypes included P. aeruginosa isolates with hallmarks of adaptation to the CF airways, including loss of motility, low production of siderophore, pyocyanin and proteases, and antibiotic resistance. One of these pulsotypes grouped a high percentage of hypermutable isolates. No clear correlation between epidemiological and clinical data was found.

Conclusions: We conclude that CF patients of this cohort shared common pulsotypes, but their phenotypic heterogeneity indicates an absence of specific traits associated to P. aeruginosa genotypic prevalence.

No MeSH data available.


Related in: MedlinePlus

Distribution of isolates among profiles of different sizes. P. aeruginosa isolates were subjected to PFGE and DNA band patterns were analysed. The distribution of isolates among the profiles is shown
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Fig1: Distribution of isolates among profiles of different sizes. P. aeruginosa isolates were subjected to PFGE and DNA band patterns were analysed. The distribution of isolates among the profiles is shown

Mentions: PFGE was carried out for all 338 P. aeruginosa isolates. By setting the similarity cut-off at 90 %, 214 PFGE profiles were classified as unique pulsotypes of single patients (Fig. 1). Of the 43 clusters of strains detected, 25 clusters included at least two or more P. aeruginosa isolates showing identical PFGE profile (100 % similarity) or belonging to highly related subtypes (≥90 % similarity), and these were classified as “PFGE patterns” (P). The remaining 18 clusters grouped two or more P. aeruginosa isolates which were highly related to each other (≥90 % similarity), but none of them identical, and these were classified as “PFGE correlated profiles” (CP). Four major PFGE clusters, including more than three isolates, were detected: P1, P6, P14 and CP2 (Fig. 2). The contacts investigation showed no clear link among patients with the same PFGE profile. Cluster P1 included P. aeruginosa isolates from eight CF patients, distributed in four highly related subtypes. Two P1 subtypes (P1.0 and P1.1) included three indistinguishable P. aeruginosa isolates each. Cluster P6 included isolates from six patients, five of them identical (100 % similarity) (P6.0) and one highly related (97 % similarity) to subtype P6.0. Cluster P14 included isolates from 12 patients, distributed in six highly related subtypes, one of them grouping four indistinguishable isolates (P14.0) and three grouping two indistinguishable isolates each (P14.1, P14.2 and P14.3). Cluster CP2 included isolates highly related to each other derived from eight CF patients’ clustering with a similarity ≥90 % (CP2.0 – CP2.7). The remaining 304 isolates presented unique PFGE profiles (63.3 % of the total strains) or were included in other minor PFGE clusters, grouping two or three P. aeruginosa isolates (26.6 %) with a similarity of at least 90 %. One pair of siblings harboured an indistinguishable genotype (P13), while two pairs were infected by highly related P. aeruginosa isolates (CP7 and CP18). The genotype and the characteristics of patients with P. aeruginosa isolates belonging to the prevalent PFGE clusters (P1, P6, P14 and CP2) are reported in Table 1 and summarized in Table 2. Overall, these findings indicate that a P. aeruginosa outbreak was not found, despite the presence of prevalent pulsotypes, potentially due to sporadic cross-transmission.Fig. 1


Genotypic and phenotypic relatedness of Pseudomonas aeruginosa isolates among the major cystic fibrosis patient cohort in Italy.

Cigana C, Melotti P, Baldan R, Pedretti E, Pintani E, Iansa P, De Fino I, Favari F, Bergamini G, Tridello G, Cirillo DM, Assael BM, Bragonzi A - BMC Microbiol. (2016)

Distribution of isolates among profiles of different sizes. P. aeruginosa isolates were subjected to PFGE and DNA band patterns were analysed. The distribution of isolates among the profiles is shown
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4940697&req=5

Fig1: Distribution of isolates among profiles of different sizes. P. aeruginosa isolates were subjected to PFGE and DNA band patterns were analysed. The distribution of isolates among the profiles is shown
Mentions: PFGE was carried out for all 338 P. aeruginosa isolates. By setting the similarity cut-off at 90 %, 214 PFGE profiles were classified as unique pulsotypes of single patients (Fig. 1). Of the 43 clusters of strains detected, 25 clusters included at least two or more P. aeruginosa isolates showing identical PFGE profile (100 % similarity) or belonging to highly related subtypes (≥90 % similarity), and these were classified as “PFGE patterns” (P). The remaining 18 clusters grouped two or more P. aeruginosa isolates which were highly related to each other (≥90 % similarity), but none of them identical, and these were classified as “PFGE correlated profiles” (CP). Four major PFGE clusters, including more than three isolates, were detected: P1, P6, P14 and CP2 (Fig. 2). The contacts investigation showed no clear link among patients with the same PFGE profile. Cluster P1 included P. aeruginosa isolates from eight CF patients, distributed in four highly related subtypes. Two P1 subtypes (P1.0 and P1.1) included three indistinguishable P. aeruginosa isolates each. Cluster P6 included isolates from six patients, five of them identical (100 % similarity) (P6.0) and one highly related (97 % similarity) to subtype P6.0. Cluster P14 included isolates from 12 patients, distributed in six highly related subtypes, one of them grouping four indistinguishable isolates (P14.0) and three grouping two indistinguishable isolates each (P14.1, P14.2 and P14.3). Cluster CP2 included isolates highly related to each other derived from eight CF patients’ clustering with a similarity ≥90 % (CP2.0 – CP2.7). The remaining 304 isolates presented unique PFGE profiles (63.3 % of the total strains) or were included in other minor PFGE clusters, grouping two or three P. aeruginosa isolates (26.6 %) with a similarity of at least 90 %. One pair of siblings harboured an indistinguishable genotype (P13), while two pairs were infected by highly related P. aeruginosa isolates (CP7 and CP18). The genotype and the characteristics of patients with P. aeruginosa isolates belonging to the prevalent PFGE clusters (P1, P6, P14 and CP2) are reported in Table 1 and summarized in Table 2. Overall, these findings indicate that a P. aeruginosa outbreak was not found, despite the presence of prevalent pulsotypes, potentially due to sporadic cross-transmission.Fig. 1

Bottom Line: Here, we look at the major CF patient cohort in Italy to identify shared P. aeruginosa clones and associated common phenotypic traits.No clear correlation between epidemiological and clinical data was found.We conclude that CF patients of this cohort shared common pulsotypes, but their phenotypic heterogeneity indicates an absence of specific traits associated to P. aeruginosa genotypic prevalence.

View Article: PubMed Central - PubMed

Affiliation: Infections and Cystic Fibrosis Unit, Division of Immunology, Transplantation and Infectious Diseases, IRCCS San Raffaele Scientific Institute, via Olgettina 58, 20132, Milan, Italy. cigana.cristina@hsr.it.

ABSTRACT

Background: Pseudomonas aeruginosa is the predominant pathogen associated with the decline of pulmonary function in cystic fibrosis (CF) patients. Both environment-to-host acquisition and patient-to-patient transmission have been described for P. aeruginosa infection. Epidemic clones and bacterial phenotypic adaptation to the CF lung have been recognised as independent risk factors for disease progression. So far, there is no established link between genotypic prevalence and phenotypic traits. Here, we look at the major CF patient cohort in Italy to identify shared P. aeruginosa clones and associated common phenotypic traits.

Results: A comprehensive analysis of P. aeruginosa genotypes to determine the presence of high-risk shared clones and their association to specific phenotypic traits has been performed in a major Italian CF centre. Pulsed-field gel electrophoresis (PFGE) of P. aeruginosa isolates from 338 CF subjects identified 43 profiles shared by two or more patients and 214 profiles exclusive to individual patients. There was no evidence of a P. aeruginosa outbreak, but four most prevalent pulsotypes were detected. Common phenotypic traits were recorded intra-pulsotypes, but we detected heterogeneity inter-pulsotypes. Two of the four major pulsotypes included P. aeruginosa isolates with hallmarks of adaptation to the CF airways, including loss of motility, low production of siderophore, pyocyanin and proteases, and antibiotic resistance. One of these pulsotypes grouped a high percentage of hypermutable isolates. No clear correlation between epidemiological and clinical data was found.

Conclusions: We conclude that CF patients of this cohort shared common pulsotypes, but their phenotypic heterogeneity indicates an absence of specific traits associated to P. aeruginosa genotypic prevalence.

No MeSH data available.


Related in: MedlinePlus