Project description:Bacterial infections of wounds are associated with poor healing and worse scarring. We sought to identify transcriptomic patterns associated with impaired healing of wounds infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) using a rabbit ear wound model. Wounds created on post-operative day (POD) 0 were infected on POD3, within the inflammatory phase of healing. On POD4 the infected wounds were harvested for microarray/transcriptome analysis. Other wounds with 24-hour infections were treated with topical antibiotic to promote biofilm formation and harvested on POD6 or POD12. On POD4 before antibiotic treatment, both wounds contained elevated transcripts that enriched predominantly into inflammation/infection-response pathways and functions characteristic of infiltrating leukocytes. But there were 5-fold more elevated transcripts in P.a.- than K.p.-infected wounds. Additionally, unique to P.a.-infected wounds, was a minor network of inflammation/infection-response molecules with predicted upstream regulation predominated by type I interferons. Also on POD4, Dnr-transcripts of both wounds were enriched into stress-response pathways such as EIF2 signaling. But there were 8-fold more Dnr-transcripts in P.a.- than K.p.-infected wounds, and many more of them enriched in the function, cell death, suggesting that resident dermal cells of P.a.-infected wounds failed to survive a more destructive P.a. infection. On POD6, following two days of antibiotic treatment, the biofilm-colonized wounds expressed magnitudes fewer inflammation and stress-response transcripts. However, a single regulatory network of P.a.-infected wounds was found to consist of Upr-transcripts enriching immune/infection-response functions predicted to be regulated by type I interferons, which was similar to the network unique to P.a.-infected wounds on POD4. On POD12, genes expressed by K.p.-infected wounds suggesting healing, while for P.a.-infected wounds they suggested stalled healing. The similarities and differences between the wound responses to these infections further define the molecular foundations of healing impaired by infections.

Project description:Bacterial infections of wounds are associated with poor healing and worse scarring. We sought to identify transcriptomic patterns associated with impaired healing of wounds infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) using a rabbit ear wound model. Wounds created on post-operative day (POD) 0 were infected on POD3, within the inflammatory phase of healing. On POD4 the infected wounds were harvested for microarray/transcriptome analysis. Other wounds with 24-hour infections were treated with topical antibiotic to promote biofilm formation and harvested on POD6 or POD12. On POD4 before antibiotic treatment, both wounds contained elevated transcripts that enriched predominantly into inflammation/infection-response pathways and functions characteristic of infiltrating leukocytes. But there were 5-fold more elevated transcripts in P.a.- than K.p.-infected wounds. Additionally, unique to P.a.-infected wounds, was a minor network of inflammation/infection-response molecules with predicted upstream regulation predominated by type I interferons. Also on POD4, Dnr-transcripts of both wounds were enriched into stress-response pathways such as EIF2 signaling. But there were 8-fold more Dnr-transcripts in P.a.- than K.p.-infected wounds, and many more of them enriched in the function, cell death, suggesting that resident dermal cells of P.a.-infected wounds failed to survive a more destructive P.a. infection. On POD6, following two days of antibiotic treatment, the biofilm-colonized wounds expressed magnitudes fewer inflammation and stress-response transcripts. However, a single regulatory network of P.a.-infected wounds was found to consist of Upr-transcripts enriching immune/infection-response functions predicted to be regulated by type I interferons, which was similar to the network unique to P.a.-infected wounds on POD4. On POD12, genes expressed by K.p.-infected wounds suggesting healing, while for P.a.-infected wounds they suggested stalled healing. The similarities and differences between the wound responses to these infections further define the molecular foundations of healing impaired by infections. Rabbit ear Wounds created on post-operative day (POD) 0 were infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) on POD3 and harvested on POD4 for RNA extraction. Other wounds with 24-hour infections were treated with topical antibiotic to promote biofilm formation and harvested on POD6 or POD12.

Project description:Klebsiella pneumoniae carbapenemase (KPC)-producing Pseudomonas aeruginosa (KPC-PA) has been reported sporadically. However, epidemiological and antimicrobial susceptibility data specific for KPC-PA are lacking. We collected 374 carbapenem-resistant P. aeruginosa (CRPA) isolates from seven hospitals in China from June 2016 to February 2019 and identified the blaKPC-2 gene in 40.4% (n = 151/374) of the isolates. Approximately one-half of all KPC-PA isolates (n = 76/151; 50.3%) were resistant to ceftazidime-avibactam (CAZ-AVI). Combining Kraken2 taxonomy identification and Nanopore sequencing, we identified eight plasmid types, five of which carried blaKPC-2, and 13 combination patterns of these plasmid types. In addition, we identified IS26-ΔTn6296 and Tn1403-like-ΔTn6296 as the two mobile genetic elements that mediated blaKPC-2 transmission. blaKPC-2 plasmid curing in 28 strains restored CAZ-AVI susceptibility, suggesting that blaKPC-2 was the mediator of CAZ-AVI resistance. Furthermore, the blaKPC-2 copy number was found to correlate with KPC expression and, therefore, CAZ-AVI resistance. Taken together, our results suggest that KPC-PA is becoming a clinical threat and that using CAZ-AVI to treat this specific pathogen should be done with caution. IMPORTANCE Previous research has reported several cases of KPC-PA strains and three KPC-encoding P. aeruginosa plasmid types in China. However, the prevalence and clinical significance of KPC-PA are not available. In addition, the susceptibility of the strains to CAZ-AVI remains unknown. Samples in this study were collected from seven tertiary hospitals prior to CAZ-AVI clinical approval in China. Therefore, our results represent a retrospective study establishing the baseline efficacy of the novel β-lactam/β-lactamase combination agent for treating KPC-PA infections. The observed correlation between the blaKPC copy number and CAZ-AVI resistance suggests that close monitoring of the susceptibility of the strain during treatment is required. It would also be beneficial to screen for the blaKPC gene in CRPA strains for antimicrobial surveillance purposes.

Project description:BackgroundBacterial infections of wounds impair healing and worsen scarring. We hypothesized that transcriptome analysis of wounds infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) would indicate host-responses associated with the worse healing of P.a.- than K.p.-infected wounds.MethodsWounds created on post-operative day (POD) 0 were infected during the inflammatory phase of healing on POD3 and were harvested on POD4 for microarray and transcriptome analysis. Other wounds received topical antibiotic after infection for 24 hours to promote biofilm development, and were harvested on POD6 or POD12.ResultsWounds infected for 24 hours, relative to uninfected wounds, elevated transcripts of immune-response functions characteristic of infiltrating leukocytes. But P.a.-infected wounds elevated many more transcripts and to higher levels than K.p.-infected wounds. Coincidently, suppressed transcripts of both wounds enriched into stress-response pathways, including EIF2 signaling; however, this was more extensive for P.a.-infected wounds, including many-fold more transcripts enriching in the 'cell death' annotation, suggesting resident cutaneous cell toxicity in response to a more damaging P.a. inflammatory milieu. The POD6 wounds were colonized with biofilm but expressed magnitudes fewer immune-response transcripts with no stress-response enrichments. However, elevated transcripts of P.a.-infected wounds were inferred to be regulated by type I interferons, similar to a network unique to P.a.-infected wounds on POD4. On POD12, transcripts that were more elevated in K.p.-infected wounds suggested healing, while transcripts more elevated in P.a.-infected wounds indicated inflammation.ConclusionsAn extensive inflammatory response of wounds was evident from upregulated transcripts 24 hours after infection with either bacterium, but the response was more intense for P.a.- than K.p.-infected wounds. Coincidently, more extensive down-regulated transcripts of P.a.-infected wounds indicated a stronger "integrated stress response" to the inflammatory milieu that tipped more toward cutaneous cell death. Unique to P.a.-infected wounds on POD4 and POD6 were networks inferred to be regulated by interferons, which may result from intracellular replication of P.a. These data point to specific downregulated transcripts of cells resident to the wound as well as upregulated transcripts characteristic of infiltrating leukocytes that could be useful markers of poorly healing wounds and indicators of wound-specific treatments for improving outcomes.

Dataset Information

Protein secretion in Pseudomonas aeruginosa: the xcpA gene encodes an integral inner membrane protein homologous to Klebsiella pneumoniae secretion function protein PulO.

Publications

Protein secretion in Pseudomonas aeruginosa: the xcpA gene encodes an integral inner membrane protein homologous to Klebsiella pneumoniae secretion function protein PulO.

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