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Comparative genomics and biological characterization of sequential Pseudomonas aeruginosa isolates from persistent airways infection.

Bianconi I, Jeukens J, Freschi L, Alcalá-Franco B, Facchini M, Boyle B, Molinaro A, Kukavica-Ibrulj I, Tümmler B, Levesque RC, Bragonzi A - BMC Genomics (2015)

Bottom Line: Pathological analysis of murine lungs confirmed advanced chronic pulmonary disease, inflammation and mucus secretory cells hyperplasia.Further, comparative genomic analyses with sequential RP isolates showed signatures of pathoadaptive mutations in virulence factors potentially linked to the development of chronic infections in CF.The genome plasticity of P. aeruginosa particularly in the RP73 strain strongly indicated that these alterations may form the genetic basis defining host-bacteria interactions leading to a persistent lifestyle in human lungs.

View Article: PubMed Central - PubMed

Affiliation: Infections and Cystic Fibrosis Unit, Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milano, Italy. bianconi.irene@hsr.it.

ABSTRACT

Background: Pseudomonas aeruginosa establishes life-long chronic airway infections in cystic fibrosis (CF) patients. As the disease progresses, P. aeruginosa pathoadaptive variants are distinguished from the initially acquired strain. However, the genetic basis and the biology of host-bacteria interactions leading to a persistent lifestyle of P. aeruginosa are not understood. As a model system to study long term and persistent CF infections, the P. aeruginosa RP73, isolated 16.9 years after the onset of airways colonization from a CF patient, was investigated. Comparisons with strains RP1, isolated at the onset of the colonization, and clonal RP45, isolated 7 years before RP73 were carried out to better characterize genomic evolution of P. aeruginosa in the context of CF pathogenicity.

Results: Virulence assessments in disease animal model, genome sequencing and comparative genomics analysis were performed for clinical RP73, RP45, RP1 and prototype strains. In murine model, RP73 showed lower lethality and a remarkable capability of long-term persistence in chronic airways infection when compared to other strains. Pathological analysis of murine lungs confirmed advanced chronic pulmonary disease, inflammation and mucus secretory cells hyperplasia. Genomic analysis predicted twelve genomic islands in the RP73 genome, some of which distinguished RP73 from other prototype strains and corresponded to regions of genome plasticity. Further, comparative genomic analyses with sequential RP isolates showed signatures of pathoadaptive mutations in virulence factors potentially linked to the development of chronic infections in CF.

Conclusions: The genome plasticity of P. aeruginosa particularly in the RP73 strain strongly indicated that these alterations may form the genetic basis defining host-bacteria interactions leading to a persistent lifestyle in human lungs.

No MeSH data available.


Related in: MedlinePlus

P. aeruginosa sequential isolates from patient RP. Two clone types (OC2E and OC4A) of P. aeruginosa strains were isolated from patient RP who is heterozygous for F508del and R1162X mutations in the CFTR gene. OC2E was isolated at the onset of chronic colonization for the first eleven years. Thereafter OC4A became the dominant clone. Strain RP1 belongs to the clone type OC2E and was the first P .aeruginosa strains isolated. Strains RP45 and RP7 belong to the clone type OC4A and were isolated after 10 and 16.9 years respectively after the onset of chronic colonization of the patient’s airways with P. aeruginosa (Additional file 1 and Cramer et al. [12]). Lung function parameters at the time of P. aeruginosa isolation are indicated
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Fig1: P. aeruginosa sequential isolates from patient RP. Two clone types (OC2E and OC4A) of P. aeruginosa strains were isolated from patient RP who is heterozygous for F508del and R1162X mutations in the CFTR gene. OC2E was isolated at the onset of chronic colonization for the first eleven years. Thereafter OC4A became the dominant clone. Strain RP1 belongs to the clone type OC2E and was the first P .aeruginosa strains isolated. Strains RP45 and RP7 belong to the clone type OC4A and were isolated after 10 and 16.9 years respectively after the onset of chronic colonization of the patient’s airways with P. aeruginosa (Additional file 1 and Cramer et al. [12]). Lung function parameters at the time of P. aeruginosa isolation are indicated

Mentions: CF was suspected in the exocrine-insufficient patient index case RP (CFTR genotype: F508del/R1162X) by a positive meconium test at birth and was confirmed by pathological sweat tests at the age of 4 months. The RP patient’s airways became colonized with P. aeruginosa by the age of 7 years (Fig. 1). The CF clinic in Hannover has collected sequential isolates from this patient since the onset of colonization for up to 28 years [11]. The patient was chronically carrying P. aeruginosa isolates of clone type OC2E, for the first eleven years. During this time period strains of the clone type OC4A were sporadically isolated, but thereafter OC4A has become the dominant clone type until today. The RP patient received one to four annual 2-week courses of intravenous (iv) antipseudomonal chemotherapy since onset of colonization and was administered aerosolized colistin on a daily basis during the last 17 years. The last clone type OC2E strain was isolated from the patient’s sputum four months after the start of colistin inhalation. The patient’s clinical status remained stable during the 28 years of chronic airway infection. Lung function parameters fluctuated between 70 and 90 % predicted for forced vital capacity (FVC) and 60–80 % forced expiratory volume (FEV1) during the last 20 years with no tendency to irreversible decline.Fig. 1


Comparative genomics and biological characterization of sequential Pseudomonas aeruginosa isolates from persistent airways infection.

Bianconi I, Jeukens J, Freschi L, Alcalá-Franco B, Facchini M, Boyle B, Molinaro A, Kukavica-Ibrulj I, Tümmler B, Levesque RC, Bragonzi A - BMC Genomics (2015)

P. aeruginosa sequential isolates from patient RP. Two clone types (OC2E and OC4A) of P. aeruginosa strains were isolated from patient RP who is heterozygous for F508del and R1162X mutations in the CFTR gene. OC2E was isolated at the onset of chronic colonization for the first eleven years. Thereafter OC4A became the dominant clone. Strain RP1 belongs to the clone type OC2E and was the first P .aeruginosa strains isolated. Strains RP45 and RP7 belong to the clone type OC4A and were isolated after 10 and 16.9 years respectively after the onset of chronic colonization of the patient’s airways with P. aeruginosa (Additional file 1 and Cramer et al. [12]). Lung function parameters at the time of P. aeruginosa isolation are indicated
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4696338&req=5

Fig1: P. aeruginosa sequential isolates from patient RP. Two clone types (OC2E and OC4A) of P. aeruginosa strains were isolated from patient RP who is heterozygous for F508del and R1162X mutations in the CFTR gene. OC2E was isolated at the onset of chronic colonization for the first eleven years. Thereafter OC4A became the dominant clone. Strain RP1 belongs to the clone type OC2E and was the first P .aeruginosa strains isolated. Strains RP45 and RP7 belong to the clone type OC4A and were isolated after 10 and 16.9 years respectively after the onset of chronic colonization of the patient’s airways with P. aeruginosa (Additional file 1 and Cramer et al. [12]). Lung function parameters at the time of P. aeruginosa isolation are indicated
Mentions: CF was suspected in the exocrine-insufficient patient index case RP (CFTR genotype: F508del/R1162X) by a positive meconium test at birth and was confirmed by pathological sweat tests at the age of 4 months. The RP patient’s airways became colonized with P. aeruginosa by the age of 7 years (Fig. 1). The CF clinic in Hannover has collected sequential isolates from this patient since the onset of colonization for up to 28 years [11]. The patient was chronically carrying P. aeruginosa isolates of clone type OC2E, for the first eleven years. During this time period strains of the clone type OC4A were sporadically isolated, but thereafter OC4A has become the dominant clone type until today. The RP patient received one to four annual 2-week courses of intravenous (iv) antipseudomonal chemotherapy since onset of colonization and was administered aerosolized colistin on a daily basis during the last 17 years. The last clone type OC2E strain was isolated from the patient’s sputum four months after the start of colistin inhalation. The patient’s clinical status remained stable during the 28 years of chronic airway infection. Lung function parameters fluctuated between 70 and 90 % predicted for forced vital capacity (FVC) and 60–80 % forced expiratory volume (FEV1) during the last 20 years with no tendency to irreversible decline.Fig. 1

Bottom Line: Pathological analysis of murine lungs confirmed advanced chronic pulmonary disease, inflammation and mucus secretory cells hyperplasia.Further, comparative genomic analyses with sequential RP isolates showed signatures of pathoadaptive mutations in virulence factors potentially linked to the development of chronic infections in CF.The genome plasticity of P. aeruginosa particularly in the RP73 strain strongly indicated that these alterations may form the genetic basis defining host-bacteria interactions leading to a persistent lifestyle in human lungs.

View Article: PubMed Central - PubMed

Affiliation: Infections and Cystic Fibrosis Unit, Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milano, Italy. bianconi.irene@hsr.it.

ABSTRACT

Background: Pseudomonas aeruginosa establishes life-long chronic airway infections in cystic fibrosis (CF) patients. As the disease progresses, P. aeruginosa pathoadaptive variants are distinguished from the initially acquired strain. However, the genetic basis and the biology of host-bacteria interactions leading to a persistent lifestyle of P. aeruginosa are not understood. As a model system to study long term and persistent CF infections, the P. aeruginosa RP73, isolated 16.9 years after the onset of airways colonization from a CF patient, was investigated. Comparisons with strains RP1, isolated at the onset of the colonization, and clonal RP45, isolated 7 years before RP73 were carried out to better characterize genomic evolution of P. aeruginosa in the context of CF pathogenicity.

Results: Virulence assessments in disease animal model, genome sequencing and comparative genomics analysis were performed for clinical RP73, RP45, RP1 and prototype strains. In murine model, RP73 showed lower lethality and a remarkable capability of long-term persistence in chronic airways infection when compared to other strains. Pathological analysis of murine lungs confirmed advanced chronic pulmonary disease, inflammation and mucus secretory cells hyperplasia. Genomic analysis predicted twelve genomic islands in the RP73 genome, some of which distinguished RP73 from other prototype strains and corresponded to regions of genome plasticity. Further, comparative genomic analyses with sequential RP isolates showed signatures of pathoadaptive mutations in virulence factors potentially linked to the development of chronic infections in CF.

Conclusions: The genome plasticity of P. aeruginosa particularly in the RP73 strain strongly indicated that these alterations may form the genetic basis defining host-bacteria interactions leading to a persistent lifestyle in human lungs.

No MeSH data available.


Related in: MedlinePlus