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Fagon JY, Chastre J, Hance AJ, Montravers P, Novara A, Gibert C. Nosocomial pneumonia in ventilated patients: a cohort study evaluating attributable mortality and hospital stay. Am J Med 1993; 94:281-8. [PMID: 8452152 DOI: 10.1016/0002-9343(93)90060-3] [Citation(s) in RCA: 731] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
PURPOSE Although nosocomial pneumonia is a common problem in intubated and ventilated patients, previous studies have not clearly demonstrated that nosocomial pneumonia actually results in increased mortality or prolongs hospitalization of these patients. In an attempt to answer these questions, we have performed a cohort study in which patients who developed nosocomial pneumonia and control subjects were carefully matched for the severity of underlying illness and other important variables. PATIENTS AND METHODS Case patients were 48 ventilated patients with nosocomial pneumonia identified on the basis of results of protected specimen brush quantitative culture and identification of intracellular organisms in cells recovered by bronchoalveolar lavage. For matching cases and their respective controls, the following variables were used: age (+/- 5 years), Simplified Acute Physiologic Score (+/- 3 points), indication for ventilatory support, date of admission, and duration of exposure to risk. RESULTS Successful matching was achieved for 222 of 240 (92.5%) variables. The mortality rate in cases was 26 of 48 (54.2%) compared with 13 of 48 (27.1%) in controls. The attributable mortality was 27.1% (95% confidence interval [CI], 8.3% to 45.9%; p < 0.01) and the risk ratio for death was 2.0 (95% CI, 1.61 to 2.49). The mean length of stay was 34 days for cases and 21 days for controls (p < 0.02). In the case of pneumonia due to Pseudomonas or Acinetobacter species, the mortality rate was 71.4%, the attributable mortality was 42.8% (95% CI, 14.5% to 69.0%), and the risk ratio was 2.50 (95% CI, 1.31 to 4.61). CONCLUSION Pneumonias occurring in ventilated patients, especially those due to Pseudomonas or Acinetobacter species, are associated with considerable mortality in excess of that resulting from the underlying disease alone, and significantly prolong the length of stay in the intensive care unit.
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Petersen M, Brodersen P, Naested H, Andreasson E, Lindhart U, Johansen B, Nielsen HB, Lacy M, Austin MJ, Parker JE, Sharma SB, Klessig DF, Martienssen R, Mattsson O, Jensen AB, Mundy J. Arabidopsis map kinase 4 negatively regulates systemic acquired resistance. Cell 2000; 103:1111-20. [PMID: 11163186 DOI: 10.1016/s0092-8674(00)00213-0] [Citation(s) in RCA: 596] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Transposon inactivation of Arabidopsis MAP kinase 4 produced the mpk4 mutant exhibiting constitutive systemic acquired resistance (SAR) including elevated salicylic acid (SA) levels, increased resistance to virulent pathogens, and constitutive pathogenesis-related gene expression shown by Northern and microarray hybridizations. MPK4 kinase activity is required to repress SAR, as an inactive MPK4 form failed to complement mpk4. Analysis of mpk4 expressing the SA hydroxylase NahG and of mpk4/npr1 double mutants indicated that SAR expression in mpk4 is dependent upon elevated SA levels but is independent of NPR1. PDF1.2 and THI2.1 gene induction by jasmonate was blocked in mpk4 expressing NahG, suggesting that MPK4 is required for jasmonic acid-responsive gene expression.
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Glazebrook J, Rogers EE, Ausubel FM. Isolation of Arabidopsis mutants with enhanced disease susceptibility by direct screening. Genetics 1996; 143:973-82. [PMID: 8725243 PMCID: PMC1207353 DOI: 10.1093/genetics/143.2.973] [Citation(s) in RCA: 440] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
To discover which components of plant defense responses make significant contributions to limiting pathogen attack, we screened a mutagenized population of Arabidopsis thaliana for individuals that exhibit increased susceptibility to the moderately virulent bacterial pathogen Pseudomonas syringae pv. maculicola ES4326 (Psm ES4326). The 12 enhanced disease susceptibility (eds) mutants isolated included alleles of two genes involved in phytoalexin biosynthesis (pad2, which had been identified previously, and pad4, which had not been identified previously), two alleles of the previously identified npr1 gene, which affects expression of other defense genes, and alleles of seven previously unidentified genes of unknown function. The npr1 mutations caused greatly reduced expression of the PR1 gene in response to PsmES4326 infection, but had little effect on expression of two other defense genes, BGL2 and PR5, suggesting that PR1 expression may be important for limiting growth of PsmES4326. While direct screens for mutants with quantitative pathogen-susceptibility phenotypes have not been reported previously, our finding that mutants isolated in this way include those affected in known defense responses supports the notion that this type of screening strategy allows genetic dissection of the roles of various plant defense responses in disease resistance.
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Mindrinos M, Katagiri F, Yu GL, Ausubel FM. The A. thaliana disease resistance gene RPS2 encodes a protein containing a nucleotide-binding site and leucine-rich repeats. Cell 1994; 78:1089-99. [PMID: 7923358 DOI: 10.1016/0092-8674(94)90282-8] [Citation(s) in RCA: 394] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In plants, resistance to a pathogen is frequently correlated with a genetically defined interaction between a plant resistance gene and a corresponding pathogen avirulence gene. A simple model explains these gene-for-gene interactions: avirulence gene products generate signals (ligands), and resistance genes encode cognate receptors. The A. thaliana RPS2 gene confers resistance to the bacterial pathogen P. syringae carrying the avirulence gene avrRpt2. A map-based positional cloning strategy was used to identify RPS2. The identification of RPS2 was verified using a newly developed transient assay for RPS2 function and by genetic complementation in transgenic plants. RPS2 encodes a novel 105 kDa protein containing a leucine zipper, a nucleotide-binding site, and 14 imperfect leucine-rich repeats.
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Comparative Study |
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Bachofen M, Weibel ER. Alterations of the gas exchange apparatus in adult respiratory insufficiency associated with septicemia. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1977; 116:589-615. [PMID: 921049 DOI: 10.1164/arrd.1977.116.4.589] [Citation(s) in RCA: 379] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Case Reports |
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379 |
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Koeppen K, Hampton TH, Jarek M, Scharfe M, Gerber SA, Mielcarz DW, Demers EG, Dolben EL, Hammond JH, Hogan DA, Stanton BA. A Novel Mechanism of Host-Pathogen Interaction through sRNA in Bacterial Outer Membrane Vesicles. PLoS Pathog 2016; 12:e1005672. [PMID: 27295279 PMCID: PMC4905634 DOI: 10.1371/journal.ppat.1005672] [Citation(s) in RCA: 342] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 05/10/2016] [Indexed: 12/20/2022] Open
Abstract
Bacterial outer membrane vesicle (OMV)-mediated delivery of proteins to host cells is an important mechanism of host-pathogen communication. Emerging evidence suggests that OMVs contain differentially packaged short RNAs (sRNAs) with the potential to target host mRNA function and/or stability. In this study, we used RNA-Seq to characterize differentially packaged sRNAs in Pseudomonas aeruginosa OMVs, and to show transfer of OMV sRNAs to human airway cells. We selected one sRNA for further study based on its stable secondary structure and predicted mRNA targets. Our candidate sRNA (sRNA52320), a fragment of a P. aeruginosa methionine tRNA, was abundant in OMVs and reduced LPS-induced as well as OMV-induced IL-8 secretion by cultured primary human airway epithelial cells. We also showed that sRNA52320 attenuated OMV-induced KC cytokine secretion and neutrophil infiltration in mouse lung. Collectively, these findings are consistent with the hypothesis that sRNA52320 in OMVs is a novel mechanism of host-pathogen interaction whereby P. aeruginosa reduces the host immune response. Pseudomonas aeruginosa is a gram-negative, opportunistic pathogen that accounts for about 10% of all hospital-acquired infections in the US and primarily infects immunocompromised hosts, including patients with chronic obstructive pulmonary disease and cystic fibrosis. Gram-negative bacteria like P. aeruginosa produce outer membrane vesicles (OMVs), which constitute an important mechanism for host colonization. In this study we demonstrate a novel mechanism of pathogen-host interaction that attenuates the innate immune response in human airway epithelial cells and in mouse lung through a regulatory sRNA contained inside OMVs secreted by P. aeruginosa.
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Journal Article |
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342 |
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Timsit JF, Farkas JC, Boyer JM, Martin JB, Misset B, Renaud B, Carlet J. Central vein catheter-related thrombosis in intensive care patients: incidence, risks factors, and relationship with catheter-related sepsis. Chest 1998; 114:207-13. [PMID: 9674471 DOI: 10.1378/chest.114.1.207] [Citation(s) in RCA: 326] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
OBJECTIVE To evaluate the incidence and risk factors for catheter-related central vein thrombosis in ICU patients. DESIGN Observational prospective multicenter study. SETTING An 8-bed surgical ICU, a 10-bed surgical cardiovascular ICU, and a 10-bed medical-surgical ICU. PATIENTS During an 18-month period, 265 internaljugular or subclavian catheters were included. Veins were explored by duplex scanning performed just before or < 24 h after catheter removal. Suspected risk factors of catheter-related central vein thrombosis were recorded. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS Fifty-seven catheters were excluded from the analysis. Therefore 208 catheters were analyzed. Mean age of patients was 64+/-15 years, simplified acute physiologic score was 12+/-5, organ system failure score at insertion was 1+/-1, and mean duration of catheterization was 9+/-5 days. A catheter-related internal jugular or subclavian vein thrombosis occurred in 33% of the cases (42% [95% confidence interval (CI), 34 to 49%] and 10% [95% CI, 3 to 18%], respectively). Thrombosis was limited in 8%, large in 22%, and occlusive in 3% of the cases. Internal jugular route (relative risk [RR], 4.13; 95% CI, 1.72 to 9.95), therapeutic heparinization (RR 0.47; 95% CI, 0.23 to 0.99), and age >64 years (RR, 2.44; 95% CI, 2.05 to 3.19) were independently associated with catheter-related thrombosis. Moreover, the risk of catheter-related sepsis was 2.62-fold higher when thrombosis occurred (p=0.011). CONCLUSIONS Catheter-related central vein thrombosis is a frequent complication of central venous catheterization in ICU patients and is closely associated with catheter-related sepsis.
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Multicenter Study |
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326 |
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Barkema HW, Schukken YH, Lam TJ, Beiboer ML, Wilmink H, Benedictus G, Brand A. Incidence of clinical mastitis in dairy herds grouped in three categories by bulk milk somatic cell counts. J Dairy Sci 1998; 81:411-9. [PMID: 9532494 DOI: 10.3168/jds.s0022-0302(98)75591-2] [Citation(s) in RCA: 307] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Incidence of clinical mastitis was studied in 274 herds grouped in three categories by bulk milk somatic cell count (SCC). Mean incidence rate of clinical mastitis was 0.278, 0.257, and 0.252 cases per 365 cow-days at risk in herds with low (< or = 150,000), medium (150,000 to 250,000), and high (250,000 to 400,000 cells/ml) bulk milk SCC, respectively. The incidence rate of clinical mastitis was not different among the three categories. Variance in the incidence of clinical mastitis among herds increased as bulk milk SCC decreased. Clinical mastitis caused by Gram-negative pathogens, such as Escherichia coli, Klebsiella spp., or Pseudomonas spp., occurred more often in herds with a low bulk milk SCC. Clinical mastitis caused by Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus agalactiae occurred more often in herds with a high bulk milk SCC. Systemic signs of illness caused by clinical mastitis occurred more often in herds with a low bulk milk SCC. Both overall culling rate and culling rate for clinical mastitis were not different among groups catergorized by bulk milk SCC. In herds with a high bulk milk SCC, however, more cows that produced milk with a high SCC were culled. In herds with a low bulk milk SCC, more cows were culled for teat lesions, milkability, udder shape, fertility, and character than were cows in herds with a high bulk milk SCC. In herds with a low bulk milk SCC, cows were also culled more for export and production reasons.
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307 |
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D'Argenio DA, Wu M, Hoffman LR, Kulasekara HD, Déziel E, Smith EE, Nguyen H, Ernst RK, Larson Freeman TJ, Spencer DH, Brittnacher M, Hayden HS, Selgrade S, Klausen M, Goodlett DR, Burns JL, Ramsey BW, Miller SI. Growth phenotypes of Pseudomonas aeruginosa lasR mutants adapted to the airways of cystic fibrosis patients. Mol Microbiol 2007; 64:512-33. [PMID: 17493132 PMCID: PMC2742308 DOI: 10.1111/j.1365-2958.2007.05678.x] [Citation(s) in RCA: 277] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The opportunistic pathogen Pseudomonas aeruginosa undergoes genetic change during chronic airway infection of cystic fibrosis (CF) patients. One common change is a mutation inactivating lasR, which encodes a transcriptional regulator that responds to a homoserine lactone signal to activate expression of acute virulence factors. Colonies of lasR mutants visibly accumulated the iridescent intercellular signal 4-hydroxy-2-heptylquinoline. Using this colony phenotype, we identified P. aeruginosa lasR mutants that emerged in the airway of a CF patient early during chronic infection, and during growth in the laboratory on a rich medium. The lasR loss-of-function mutations in these strains conferred a growth advantage with particular carbon and nitrogen sources, including amino acids, in part due to increased expression of the catabolic pathway regulator CbrB. This growth phenotype could contribute to selection of lasR mutants both on rich medium and within the CF airway, supporting a key role for bacterial metabolic adaptation during chronic infection. Inactivation of lasR also resulted in increased beta-lactamase activity that increased tolerance to ceftazidime, a widely used beta-lactam antibiotic. Loss of LasR function may represent a marker of an early stage in chronic infection of the CF airway with clinical implications for antibiotic resistance and disease progression.
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Research Support, N.I.H., Extramural |
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277 |
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Saiman L, Anstead M, Mayer-Hamblett N, Lands LC, Kloster M, Hocevar-Trnka J, Goss CH, Rose LM, Burns JL, Marshall BC, Ratjen F. Effect of azithromycin on pulmonary function in patients with cystic fibrosis uninfected with Pseudomonas aeruginosa: a randomized controlled trial. JAMA 2010; 303:1707-15. [PMID: 20442386 DOI: 10.1001/jama.2010.563] [Citation(s) in RCA: 251] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Azithromycin is recommended as therapy for cystic fibrosis (CF) patients with chronic Pseudomonas aeruginosa infection, but there has not been sufficient evidence to support the benefit of azithromycin in other patients with CF. OBJECTIVE To determine if azithromycin treatment improves lung function and reduces pulmonary exacerbations in pediatric CF patients uninfected with P. aeruginosa. DESIGN, SETTING, AND PARTICIPANTS A multicenter, randomized, double-blind placebo-controlled trial was conducted from February 2007 to July 2009 at 40 CF care centers in the United States and Canada. Of the 324 participants screened, 260 were randomized and received study drug. Eligibility criteria included age of 6 to 18 years, a forced expiratory volume in the first second of expiration (FEV(1)) of at least 50% predicted, and negative respiratory tract cultures for P. aeruginosa for at least 1 year. Randomization was stratified by age of 6 to 12 years vs 13 to 18 years and by CF center. INTERVENTION The active group (n = 131) received 250 mg (weight 18-35.9 kg) or 500 mg (weight > or = 36 kg) of azithromycin 3 days per week (Monday, Wednesday, and Friday) for 168 days. The placebo group (n = 129) received identically packaged placebo tablets on the same schedule. MAIN OUTCOME MEASURES The primary outcome was change in FEV(1). Exploratory outcomes included additional pulmonary function end points, pulmonary exacerbations, changes in weight and height, new use of antibiotics, and hospitalizations. Changes in microbiology and adverse events were monitored. RESULTS The mean (SD) age of participants was 10.7 (3.17) years. The mean (SD) FEV(1) at baseline and 168 days were 2.13 (0.85) L and 2.22 (0.86) L for the azithromycin group and 2.12 (0.85) L and 2.20 (0.88) L for the placebo group. The difference in the change in FEV(1) between the azithromycin and placebo groups was 0.02 L (95% confidence interval [CI], -0.05 to 0.08; P = .61). None of the exploratory pulmonary function end points were statistically significant. Pulmonary exacerbations occurred in 21% of the azithromycin group and 39% of the placebo group. Participants in the azithromycin group had a 50% reduction in exacerbations (95% CI, 31%-79%) and an increase in body weight of 0.58 kg (95% CI, 0.14-1.02) compared with placebo participants. There were no significant differences between groups in height, use of intravenous or inhaled antibiotics, or hospitalizations. Participants in the azithromycin group had no increased risk of adverse events, but had less cough (-23% treatment difference; 95% CI, -33% to -11%) and less productive cough (-11% treatment difference; 95% CI, -19% to -3%) compared with placebo participants. CONCLUSION In children and adolescents with CF uninfected with P. aeruginosa, treatment with azithromycin for 24 weeks did not result in improved pulmonary function. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00431964.
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Multicenter Study |
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251 |
12
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Goldstone J, Moore WS. Infection in vascular prostheses. Clinical manifestations and surgical management. Am J Surg 1974; 128:225-33. [PMID: 4602192 DOI: 10.1016/0002-9610(74)90097-x] [Citation(s) in RCA: 226] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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226 |
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Chan LS, Robinson N, Xu L. Expression of interleukin-4 in the epidermis of transgenic mice results in a pruritic inflammatory skin disease: an experimental animal model to study atopic dermatitis. J Invest Dermatol 2001; 117:977-83. [PMID: 11676841 DOI: 10.1046/j.0022-202x.2001.01484.x] [Citation(s) in RCA: 222] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Atopic dermatitis, a common, chronic, inflammatory skin disease that occurs with increasing prevalence, is characterized by hyperactivated cytokines of helper T cell subset 2 and is frequently associated with staphylococcal infection. An experimental animal model of atopic dermatitis induced by transgenically introduced cytokine is not available. We generated a transgenic mouse line expressing epidermal interleukin-4, a critical cytokine of helper T cell subset 2. Here we show that transgenic mice spontaneously developed a pruritic inflammatory skin disease reproducing all key features of human atopic dermatitis, including xerosis, conjunctivitis, inflammatory skin lesions, Staphylococcus aureus infection, histopathology of chronic dermatitis with T cell, mast cell, macrophage-like mononuclear cell, and eosinophil infiltration, and elevation of total serum IgE and IgG1. The onset and early progression of skin disease coincided with increased total serum IgE and IgG1. The mouse disease occurred at a 43% annual incidence rate and primarily affected the poorly haired skin: ear (100%), neck (65%), eye (53%), face (29%), tail (12%), leg (12%), and torso (6%). As a group the affected transgenic mice manifested with a skin disorder that fulfilled the clinical diagnostic criteria established for atopic dermatitis in human patients. Pending further characterization to authenticate it as a model of atopic dermatitis, this experimental animal model of pruritic inflammatory skin disease may facilitate investigations for the roles of interleukin-4 in cutaneous inflammation and skin infection in human patients.
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Stieritz DD, Holder IA. Experimental studies of the pathogenesis of infections due to Pseudomonas aeruginosa: description of a burned mouse model. J Infect Dis 1975; 131:688-91. [PMID: 805812 DOI: 10.1093/infdis/131.6.688] [Citation(s) in RCA: 180] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
An experimental burned mouse model is described that is clinically relevant to burn wound sepsis caused by Pseudomonas aeruginosa. Mice subjected to a nonlethal burn by flame were challenged with P. aeruginosa. The LD50 after subcutaneous injection in the skin of the burn up to 24 hr after the burn was smaller than 10 organisms vs. 10-6 organisms in normal animals. By three days after the burn, the value returned to and exceeded that of normal animals. This dramatic change in the LD50 after the burn was not seen when mice were challenged with other organisms. Challenge with P. aeruginosa by different routes immediately after burning showed less dramatic decreases in the LD50. Enumeration of infecting organisms in the skin of the burn and in major organs suggests the possibility of a toxic event.
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Abstract
Bacterial pneumonia is a prevalent and costly infection that is a significant cause of morbidity and mortality in patients of all ages. The continuing emergence of antibiotic-resistant bacteria (e.g., penicillin-resistant pneumococci) suggests that bacterial pneumonia will assume increasing importance in the coming years. Thus, knowledge of the pathogenesis of, and risk factors for, bacterial pneumonia is critical to the development of strategies for prevention and treatment of these infections. Bacterial pneumonia in adults is the result of aspiration of oropharyngeal flora into the lower respiratory tract and failure of host defense mechanisms to eliminate the contaminating bacteria, which multiply in the lung and cause infection. It is recognized that community-acquired pneumonia and lung abscesses can be the result of infection by anaerobic bacteria; dental plaque would seem to be a logical source of these bacteria, especially in patients with periodontal disease. It is also possible that patients with high risk for pneumonia, such as hospitalized patients and nursing home residents, are likely to pay less attention to personal hygiene than healthy patients. One important dimension of this personal neglect may be diminished attention to oral hygiene. Poor oral hygiene and periodontal disease may promote oropharyngeal colonization by potential respiratory pathogens (PRPs) including Enterobacteriaceae (Klebsiella pneumoniae, Escherichia coli, Enterobacter species, etc.), Pseudomonas aeruginosa, and Staphylococcus aureus. This paper provides the rationale for the development of this hypothesis especially as it pertains to mechanically ventilated intensive care unit patients and nursing home residents, two patient groups with a high risk for bacterial pneumonia.
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Review |
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173 |
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Yoon SS, Coakley R, Lau GW, Lymar SV, Gaston B, Karabulut AC, Hennigan RF, Hwang SH, Buettner G, Schurr MJ, Mortensen JE, Burns JL, Speert D, Boucher RC, Hassett DJ. Anaerobic killing of mucoid Pseudomonas aeruginosa by acidified nitrite derivatives under cystic fibrosis airway conditions. J Clin Invest 2006; 116:436-46. [PMID: 16440061 PMCID: PMC1350997 DOI: 10.1172/jci24684] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Accepted: 11/29/2005] [Indexed: 11/17/2022] Open
Abstract
Mucoid, mucA mutant Pseudomonas aeruginosa cause chronic lung infections in cystic fibrosis (CF) patients and are refractory to phagocytosis and antibiotics. Here we show that mucoid bacteria perish during anaerobic exposure to 15 mM nitrite (NO2) at pH 6.5, which mimics CF airway mucus. Killing required a pH lower than 7, implicating formation of nitrous acid (HNO2) and NO, that adds NO equivalents to cellular molecules. Eighty-seven percent of CF isolates possessed mucA mutations and were killed by HNO2 (3-log reduction in 4 days). Furthermore, antibiotic-resistant strains determined were also equally sensitive to HNO2. More importantly, HNO2 killed mucoid bacteria (a) in anaerobic biofilms; (b) in vitro in ultrasupernatants of airway secretions derived from explanted CF patient lungs; and (c) in mouse lungs in vivo in a pH-dependent fashion, with no organisms remaining after daily exposure to HNO2 for 16 days. HNO2 at these levels of acidity and NO2 also had no adverse effects on cultured human airway epithelia in vitro. In summary, selective killing by HNO2 may provide novel insights into the important clinical goal of eradicating mucoid P. aeruginosa from the CF airways.
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Research Support, N.I.H., Extramural |
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169 |
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D'Argenio DA, Gallagher LA, Berg CA, Manoil C. Drosophila as a model host for Pseudomonas aeruginosa infection. J Bacteriol 2001; 183:1466-71. [PMID: 11157963 PMCID: PMC95024 DOI: 10.1128/jb.183.4.1466-1471.2001] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Using the fruit fly Drosophila melanogaster as model host, we have identified mutants of the bacterium Pseudomonas aeruginosa with reduced virulence. Strikingly, all strains strongly impaired in fly killing also lacked twitching motility; most such strains had a mutation in pilGHIJKL chpABCDE, a gene cluster known to be required for twitching motility and potentially encoding a signal transduction system. The pil chp genes appear to control the expression of additional virulence factors, however, since the wild-type fly-killing phenotype of a subset of mutants isolated on the basis of their compact colony morphology indicated that twitching motility itself was not required for full virulence in the fly.
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research-article |
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168 |
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Carterson AJ, Höner zu Bentrup K, Ott CM, Clarke MS, Pierson DL, Vanderburg CR, Buchanan KL, Nickerson CA, Schurr MJ. A549 lung epithelial cells grown as three-dimensional aggregates: alternative tissue culture model for Pseudomonas aeruginosa pathogenesis. Infect Immun 2005; 73:1129-40. [PMID: 15664956 PMCID: PMC547019 DOI: 10.1128/iai.73.2.1129-1140.2005] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A three-dimensional (3-D) lung aggregate model was developed from A549 human lung epithelial cells by using a rotating-wall vessel bioreactor to study the interactions between Pseudomonas aeruginosa and lung epithelial cells. The suitability of the 3-D aggregates as an infection model was examined by immunohistochemistry, adherence and invasion assays, scanning electron microscopy, and cytokine and mucoglycoprotein production. Immunohistochemical characterization of the 3-D A549 aggregates showed increased expression of epithelial cell-specific markers and decreased expression of cancer-specific markers compared to their monolayer counterparts. Immunohistochemistry of junctional markers on A549 3-D cells revealed that these cells formed tight junctions and polarity, in contrast to the cells grown as monolayers. Additionally, the 3-D aggregates stained positively for the production of mucoglycoprotein while the monolayers showed no indication of staining. Moreover, mucin-specific antibodies to MUC1 and MUC5A bound with greater affinity to 3-D aggregates than to the monolayers. P. aeruginosa attached to and penetrated A549 monolayers significantly more than the same cells grown as 3-D aggregates. Scanning electron microscopy of A549 cells grown as monolayers and 3-D aggregates infected with P. aeruginosa showed that monolayers detached from the surface of the culture plate postinfection, in contrast to the 3-D aggregates, which remained attached to the microcarrier beads. In response to infection, proinflammatory cytokine levels were elevated for the 3-D A549 aggregates compared to monolayer controls. These findings suggest that A549 lung cells grown as 3-D aggregates may represent a more physiologically relevant model to examine the interactions between P. aeruginosa and the lung epithelium during infection.
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Research Support, U.S. Gov't, Non-P.H.S. |
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164 |
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Berger RE, Alexander ER, Harnisch JP, Paulsen CA, Monda GD, Ansell J, Holmes KK. Etiology, manifestations and therapy of acute epididymitis: prospective study of 50 cases. J Urol 1979; 121:750-4. [PMID: 379366 DOI: 10.1016/s0022-5347(17)56978-5] [Citation(s) in RCA: 139] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
There were 50 patients with acute epididymitis who were evaluated prospectively by history, examination and microbiologic studies, including cultures for aerobes, anaerobes, Neisseria gonorrhoeae, Chlamydia trachomatis and Ureaplasma urealyticum. Escherichia coli was the predominant pathogen isolated from the urine of men more than 35 years old, while Chlamydia trachomatis and Neisseria gonorrhoeae were the predominant pathogens isolated from the urethra of men less than 35 years old. The etiologic role of Escherichia coli and Chlamydia trachomatis was confirmed by isolation from epididymal aspirates from a high proportion of men with positive urine or urethral cultures for these agents. Chlamydia trachomatis epididymitis accounted for two-thirds of idiopathic epididymitis in young men and often was associated with oligospermia. Of 9 female sexual partners of men with Chlamydia trachomatis infection 6 had antibody to Chlamydia trachomatis, of whom 2 had positive cervical cultures for this organism and 2 others had non-gonococcal pelvic inflammatory disease. Antibiotic therapy with tetracycline was effective for the treatment of men with Chlamydia trachomatis epididymitis and should be offered to the female sex partners.
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Case Reports |
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SWARTZ MN, DODGE PR. BACTERIAL MENINGITIS--A REVIEW OF SELECTED ASPECTS. 1. GENERAL CLINICAL FEATURES, SPECIAL PROBLEMS AND UNUSUAL MENINGEAL REACTIONS MIMICKING BACTERIAL MENINGITIS. N Engl J Med 1965; 272:725-31 CONTD. [PMID: 14261465 DOI: 10.1056/nejm196504082721406] [Citation(s) in RCA: 136] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Review |
60 |
136 |
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HILL RB, ROWLANDS DT, RIFKIND D. INFECTIOUS PULMONARY DISEASE IN PATIENTS RECEIVING IMMUNOSUPPRESSIVE THERAPY FOR ORGAN TRANSPLANTATION. N Engl J Med 1964; 271:1021-7. [PMID: 14195753 DOI: 10.1056/nejm196411122712001] [Citation(s) in RCA: 129] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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61 |
129 |
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Sonnleitner E, Bläsi U. Regulation of Hfq by the RNA CrcZ in Pseudomonas aeruginosa carbon catabolite repression. PLoS Genet 2014; 10:e1004440. [PMID: 24945892 PMCID: PMC4063720 DOI: 10.1371/journal.pgen.1004440] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 04/30/2014] [Indexed: 01/10/2023] Open
Abstract
Carbon Catabolite repression (CCR) allows a fast adaptation of Bacteria to changing nutrient supplies. The Pseudomonas aeruginosa (PAO1) catabolite repression control protein (Crc) was deemed to act as a translational regulator, repressing functions involved in uptake and utilization of carbon sources. However, Crc of PAO1 was recently shown to be devoid of RNA binding activity. In this study the RNA chaperone Hfq was identified as the principle post-transcriptional regulator of CCR in PAO1. Hfq is shown to bind to A-rich sequences within the ribosome binding site of the model mRNA amiE, and to repress translation in vitro and in vivo. We further report that Crc plays an unknown ancillary role, as full-fledged repression of amiE and other CCR-regulated mRNAs in vivo required its presence. Moreover, we show that the regulatory RNA CrcZ, transcription of which is augmented when CCR is alleviated, binds to Hfq with high affinity. This study on CCR in PAO1 revealed a novel concept for Hfq function, wherein the regulatory RNA CrcZ acts as a decoy to abrogate Hfq-mediated translational repression of catabolic genes and thus highlights the central role of RNA based regulation in CCR of PAO1. Carbon assimilation in Bacteria is governed by a mechanism known as carbon catabolite repression (CCR). In contrast to several other bacterial clades CCR in Pseudomonas species appears to be primarily regulated at the post-transcriptional level. In this study, we have identified the RNA chaperone Hfq as the principle post-transcriptional regulator of CCR in P. aeruginosa (PAO1). Hfq is shown to act as a translational regulator and to prevent ribosome loading through binding to A-rich sequences within the ribosome binding site of mRNAs, which encode enzymes involved in carbon utilization. It has been previously shown that the synthesis of the RNA CrcZ is augmented in the presence of non-preferred carbon sources. Here, we show that the CrcZ RNA binds to and sequesters Hfq, which in turn abrogates Hfq-mediated translational repression of mRNAs, the encoded functions of which are required for the breakdown of non-preferred carbon sources. This novel mechanistic twist on Hfq function not only highlights the central role of RNA based regulation in CCR of PAO1 but also broadens the view of Hfq-mediated post-transcriptional mechanisms.
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Research Support, Non-U.S. Gov't |
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126 |
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Wagner ML, Rosenberg HS, Fernbach DJ, Singleton EB. Typhlitis: a complication of leukemia in childhood. THE AMERICAN JOURNAL OF ROENTGENOLOGY, RADIUM THERAPY, AND NUCLEAR MEDICINE 1970; 109:341-50. [PMID: 5268115 DOI: 10.2214/ajr.109.2.341] [Citation(s) in RCA: 126] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Cohen PS, Maguire JH, Weinstein L. Infective endocarditis caused by gram-negative bacteria: a review of the literature, 1945-1977. Prog Cardiovasc Dis 1980; 22:205-42. [PMID: 6986059 DOI: 10.1016/0033-0620(80)90010-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Review |
45 |
118 |
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Abstract
UNLABELLED The aim of the study was to evaluate a possible influence of selected bacterial species on healing of venous leg ulcers. Fifty-nine patients with venous leg ulcers were followed via frequent semiquantitative culture of bacteria from the ulcer surface and determination of the ulcer area over a period of 180 days. Occurrences of cellulitis were treated with systemic antibiotics. There was a significant difference in relative areas on days 90 and 180 when ulcers with growth of Pseudomonas aeruginosa were compared to those without (p = 0.0080 and 0.0133, respectively). Ulcers with P. aeruginosa were characterized to a great extent by enlargement in contrast to those without. Ulcers with growth of Staphylococcus aureus or haemolytic streptococci healed significantly more slowly than those without when relative areas were compared on day 180 (p = 0.0079 and 0.0492, respectively). Complete healing within the observation period of 180 days was observed in 10.5% of patients with P. aeruginosa and 35% of those without (p = 0.0631), in 21.6% of patients with S. aureus and 62.5% of those without (p = 0.0278), and in 10.5% of patients with haemolytic streptococci and 35% of those without (p = 0.0631). The initial areas of ulcers colonized with P. aeruginosa or S. aureus were significantly larger than those without, but no significant correlation between initial areas and ulcer healing was revealed. CONCLUSION Our results suggest that P. aeruginosa in venous leg ulcers can induce ulcer enlargement and/or cause a healing delay. The results also suggest a healing delay caused by S. aureus and haemolytic streptococci. However, conclusions have to be treated with caution since P. aeruginosa was found in combination with haemolytic streptococci in 15.3% of the patients.
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