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Dictyostelium transcriptional responses to Pseudomonas aeruginosa: common and specific effects from PAO1 and PA14 strains
Sergio Carilla-Latorre, Javier Calvo-Garrido, Gareth Bloomfield, Jason Skelton, Robert R Kay, Alasdair Ivens, José L Martinez, Ricardo Escalante
BMC Microbiology , 2008, DOI: 10.1186/1471-2180-8-109
Abstract: We have compared the virulence of the P. aeruginosa PAO1 and PA14 using D. discoideum and studied the transcriptional response of the amoeba upon infection. Our results showed that PA14 is more virulent in Dictyostelium than PA01using different plating assays. For studying the differential response of the host to infection by these model strains, D. discoideum cells were exposed to either P. aeruginosa PAO1 or P. aeruginosa PA14 (mixed with an excess of the non-pathogenic bacterium Klebsiella aerogenes as food supply) and after 4 hours, cellular RNA extracted. A three-way comparison was made using whole-genome D. discoideum microarrays between RNA samples from cells treated with the two different strains and control cells exposed only to K. aerogenes. The transcriptomic analyses have shown the existence of common and specific responses to infection. The expression of 364 genes changed in a similar way upon infection with one or another strain, whereas 169 genes were differentially regulated depending on whether the infecting strain was either P. aeruginosa PAO1 or PA14. Effects on metabolism, signalling, stress response and cell cycle can be inferred from the genes affected.Our results show that pathogenic Pseudomonas strains invoke both a common transcriptional response from Dictyostelium and a strain specific one, indicating that the infective process of bacterial pathogens can be strain-specific and is more complex than previously thought.Nosocomial infections caused by opportunistic pathogens are one of the most important health problems in developed countries. Depending on the geographic location, P. aeruginosa is the first or second causative agent of nosocomial infections [1,2]. P. aeruginosa infects patients suffering from AIDS, people at intensive care units, and burned people among others, and is the major cause of morbidity and mortality in patients with cystic fibrosis, the most prevalent hereditary disease in Caucasian populations [3]. A successful infe
Comparison of Biotyping and Antibiotyping of Pseudomonas aeruginosa Isolated from Patients with Burn Wound Infection and Nosocomial Pneumonia in Shiraz, Iran  [PDF]
Jamshid Kohanteb,Mahdieh Dayaghi,Motahareh Motazedian,Mohammad-Ali Ghayumi
Pakistan Journal of Biological Sciences , 2007,
Abstract: The objective of present study was to compare and determine the prevalence of antibiotypes and biotypes of Pseudomonas aeruginosa isolated from patients with burn infection and nosocomial pneumonia in Shiraz, Iran. Thirty isolates from each group of patients were used. Antibiotyping (antibiotic sensitivity profiles) was performed by disk diffusion of Bauer-Kirby method using eleven antibiotics and biotyping (biochemical profiles) was done by standard biochemical procedures. High rate of multi-drug resistant isolates were observed by both groups of patients. P. aeruginosa isolated from burn infection were found more resistant (26.7%) to the all antibiotics used than those from nosocomial pneumonia (6.7%) p≤0.04. All P. aeruginosa (100%) isolates from burn infection were resistant to gentamycin, carbenicillin, cephtazidime and cephalothin. The lowest resistance rate was observed with meropenem. Antibiotic susceptibility profiles revealed 11 and 15 different antibiotypes among P. aeruginosa isolates from patients with burn infection and nosocomial pneumonia, respectively. The biochemical profiles consisting of 21 biochemical tests grouped P. aeruginosa into 8 different biotypes. Biotypes BVIII 15(50%) and BIII 11(36.7%) were the most prevalent isolates from burn infection and nosocomial pneumonia, respectively p≤0.04. Data obtained in this study revealed that different types of Pseudomonas aeruginosa are involved in burn wound infection and nosocomial pneumonia in this region.
Nosocomial infections and resistance microbian in Intensive Care Unit of a University Hospital - an epidemiological study  [cached]
Adriana C. Oliveira,Wanessa T. Clemente,Thabata C. Lucas,Glaucia H. Martinho
Online Brazilian Journal of Nursing , 2006,
Abstract: In the last decades it has been observed an increase in frequency on nosocomial infections by resistant microorganisms, especially in Intensive Care Units (ICU). This study aimed to determine main sites of nosocomial infections and prevalence of multidrug resistant microorganisms. An epidemiological and descriptive study was developed in an adult ICU of a University Hospital of Belo Horizonte, Minas Gerais, from January to December, 2004. Among the most prevalent nosocomial infections were pneumonia, urinary tract infections, and bloodstream infections. Among the resistant microorganisms prevailed Pseudomonas aeruginosa, Acinetobacter baumanii, MRSA, Klebsiella, Enterobacteriaceas and Serratia. As this study is still going on, we expect to determine temporal trends for resistant microorganisms related to nosocomial infections main sites.
Nosocomial Bacterial Infections and Their Antimicrobial Resistance Patterns in University Hospitals of Hamedan, Iran  [cached]
Seyyed Hamid Hashemi,Mojgan Mamani,Shirin Jamal-Omidi,Amin Niayesh
Journal of Research in Health Sciences , 2011,
Abstract: Background: Nosocomial infections constitute a global health problem, leading to a high rate of morbidity and mortality. The aim of this study was to determine the frequency and antimicrobial resistance patterns of nosocomial infections in edu -cational hospitals of Hamadan, western Iran. Methods: During a 1-year period from April 2006 to March 2007, all patients with cul -ture-proven nosocomial infections from educational hospitals in Hamedan, west -ern Iran were included. Nosocomial infections were defined as a culture-proven infection, which occurred more than 48h after admission in the hospital. An -timicrobial susceptibility testing of isolated bacteria was performed by disc dif -fusion method. Results: A total of 170 cases of culture-proven nosocomial infections were diag -nosed. Most cases were in intensive care units (ICUs) (57.4%). The common sites of infection were lower respiratory tract (51.8%) and urinary tract (31.9%). Kleb -siella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli, were the most prevalent pathogens (32.7%, 22.9%, and 14.8% respectively). Most en -terobacteriacea isolates were resistant to third generation cephalosporins. The resis -tant rates to ceftriaxone were 75.5% for K. pneumoniae, and 76% for E. coli. Among P. aeruginosa isolates, 26.5% were resistant to ceftazidim, and 36% to cipro -floxacin. Among S. aureus isolates, 80% were methicillin-resistant. Conclusion: The patients in the ICUs are at a higher risk of nosocomial infec -tions. The high prevalence of antimicrobial resistance in the hospitals highlights the need of further infection control activities and surveillance programs.
Subinhibitory Concentration of Kanamycin Induces the Pseudomonas aeruginosa type VI Secretion System  [PDF]
Cerith Jones, Luke Allsopp, Jack Horlick, Hemantha Kulasekara, Alain Filloux
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081132
Abstract: Pseudomonas aeruginosa is a Gram-negative bacterium found in natural environments including plants, soils and warm moist surfaces. This organism is also in the top ten of nosocomial pathogens, and prevalent in cystic fibrosis (CF) lung infections. The ability of P. aeruginosa to colonize a wide variety of environments in a lasting manner is associated with the formation of a resistant biofilm and the capacity to efficiently outcompete other microorganisms. Here we demonstrate that sub-inhibitory concentration of kanamycin not only induces biofilm formation but also induces expression of the type VI secretion genes in the H1-T6SS cluster. The H1-T6SS is known for its role in toxin production and bacterial competition. We show that the antibiotic induction of the H1-T6SS only occurs when a functional Gac/Rsm pathway is present. These observations may contribute to understand how P. aeruginosa responds to antibiotic producing competitors. It also suggests that improper antibiotic therapy may enhance P. aeruginosa colonization, including in the airways of CF patients.
Análise epidemiológica de isolados clínicos de Pseudomonas aeruginosa provenientes de hospital universitário
Pires, Eduardo José Valen?a Cordeiro;Silva Júnior, Valdemir Vicente da;Lopes, Ana Catarina de Souza;Veras, Dyana Leal;Leite, Larissa Espíndola;Maciel, Maria Amélia Vieira;
Revista Brasileira de Terapia Intensiva , 2009, DOI: 10.1590/S0103-507X2009000400008
Abstract: objectives: pseudomonas aeruginosa is an increasingly prevalent opportunistic pathogen in hospital infection cases. its high resistance rates to many antimicrobials has given this microorganism a relevant role among other highly prevalent bacteria involved in nosocomial infections. this study aimed to analyze epidemiologic characteristics of p. aeruginosa and to evaluate its susceptibility to antimicrobial agents at hospital das clínicas of the universidade federal de pernambuco methods: a retrospective study was performed based on the registry book of miscellaneous secretions from the bacteriology laboratory of the hospital das clínicas involving the period between january and june 2008. among the secretions registered, were identified the positives samples for p. aeruginosa, whose origin was analyzed, as well as its susceptibility profile to routinely used in our laboratory antimicrobials. results: the bacteria most frequently isolated from miscellaneous secretions bacteria were p. aeruginosa (26%) and s. aureus (25%). p. aeruginosa was mainly isolated from respiratory infections, with 33% of positive samples for this organism from tracheal secretions and 21% from nasal. the most effective antimicrobials against p. aeruginosa were: amikacin, imipenem, meropenem and aztreonam. conclusions: these results show a high prevalence of p. aeruginosa in the hospital das clínicas of the universidade federal de pernambuco. despite featuring high resistance rates to older antimicrobials, as cephalosporins first and second generations and chloramphenicol, this pathogen showed good susceptibility to agents routinely used in this hospital.
Nosocomial infections in human immunodeficiency virus type 1 (HIV-1) infected and AIDS patients: major microorganisms and immunological profile
Panis, C.;Matsuo, T.;Reiche, E.M.V.;
Brazilian Journal of Microbiology , 2009, DOI: 10.1590/S1517-83822009000100027
Abstract: antiretroviral therapy advances have proportioned to aids patients a survival increase. at the same time, the permanence of the seropositive people in the nosocomial environment becomes common not only by the adverse reactions caused by this therapy, but also by several opportunistic diseases that take them into and out of hospital environment. during the hospital permanence, the patients expose their impaired immune system to the nosocomial virulent microorganisms, and acquire destructive nosocomial infections that sometimes can be lethal. among several hospital syndromes described, little is known about infections in immunocompromised patients and how their immune system is able to determine the course of the infection. the objective of this study was to describe the major microorganisms involved in the nosocomial infections of hiv-1 seropositive patients associated with their immunological status. the survey was carried out with the hospital infection control service records, from university hospital, londrina, paraná, southern of brazil, during the period from july 2003 to july 2004. from all the cases studied (n=969), 24 patients (2.5%) had aids diagnosis and a half of them was women with the mean of cd4+ t cells counts of 158/mm3. the main topography of the infection was pulmonary (50.0%) and the main isolated microorganisms were staphylococcus aureus, pseudomonas aeruginosa and escherichia coli. a major incidence of infection was observed in patients with cd4+ t cells counts lower than 50/mm3. the study of the relationship between the impairment of the immune system and infectious agents could provide a better healthcare of people living with hiv/aids and advances into the nosocomial infection control systems.
Lipid peroxidation by Pseudomonas aeruginosa in the pathogenesis of nosocomial sepsis.  [cached]
Giamarellos-Bourboulis E,Skiathitis S,Dionyssiou-Asteriou A,Hatziantoniou S
Journal of Postgraduate Medicine , 2003,
Abstract: BACKGROUND: To study whether Pseudomonas aeruginosa may directly trigger peroxidation of polyunsaturated fatty acids, since lipid peroxidation is a mechanism involved in the pathogenesis of sepsis. METHODS: Gamma-linolenic acid (GLA) was administered intravenously at a dose of 25mg/kg in an infusion time of 10 minutes to seven male rabbits. Blood samples were collected from the hepatic veins and from the carotid artery at regular time intervals. One clinical isolate was ex vivo incubated with the serum derived from the latter samples and concentrations of malondialdehyde (MDA) were determined during incubation in the growth medium by the thiobarbiturate assay. RESULTS: Elevated concentrations of MDA compared to their basal levels were found over the first three hours of incubation in the presence of samples collected 30 to 60 minutes after the end of the infusion of GLA. After infusion of GLA concentrations of arachidonic acid in the serum increased to concentrations comparable to those detected in sepsis. CONCLUSION: Direct triggering of lipid peroxidation by nosocomial isolates might be proposed as a pathogenetic mechanism of sepsis.
Identification of Biofilm-Associated Cluster (bac) in Pseudomonas aeruginosa Involved in Biofilm Formation and Virulence  [PDF]
Camille Macé, Damien Seyer, Chanez Chemani, Pascal Cosette, Patrick Di-Martino, Benoit Guery, Alain Filloux, Marc Fontaine, Virginie Molle, Guy-Alain Junter, Thierry Jouenne
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003897
Abstract: Biofilms are prevalent in diseases caused by Pseudomonas aeruginosa, an opportunistic and nosocomial pathogen. By a proteomic approach, we previously identified a hypothetical protein of P. aeruginosa (coded by the gene pA3731) that was accumulated by biofilm cells. We report here that a ΔpA3731 mutant is highly biofilm-defective as compared with the wild-type strain. Using a mouse model of lung infection, we show that the mutation also induces a defect in bacterial growth during the acute phase of infection and an attenuation of the virulence. The pA3731 gene is found to control positively the ability to swarm and to produce extracellular rhamnolipids, and belongs to a cluster of 4 genes (pA3729–pA3732) not previously described in P. aeruginosa. Though the protein PA3731 has a predicted secondary structure similar to that of the Phage Shock Protein, some obvious differences are observed compared to already described psp systems, e.g., this unknown cluster is monocistronic and no homology is found between the other proteins constituting this locus and psp proteins. As E. coli PspA, the amount of the protein PA3731 is enlarged by an osmotic shock, however, not affected by a heat shock. We consequently named this locus bac for biofilm-associated cluster.
Nosocomial cross-transmission of Pseudomonas aeruginosa between patients in a tertiary intensive care unit  [cached]
Dwivedi M,Mishra A,Singh R,Azim A
Indian Journal of Pathology and Microbiology , 2009,
Abstract: Background: Nosocomial infection caused by Pseudomonas aeruginosa (P. aeruginosa) is very common, despite the application of various preventive measures in intensive care units (ICUs) leading to increased morbidity, mortality, prolonged hospital stay, and increased treatment cost. Aim: The aim of the present study is to identify the source of P. aeruginosa infection in patients admitted to tertiary ICU. Materials and Methods: From 200 patients selected randomly, appropriate clinical specimens from different sites were collected and processed for the isolation and identification of the nosocomial pathogens. Surveillance samples from environmental sites and hands of nursing staff were also cultured. Results: P. aeruginosa was found to be the most common pathogen associated with nosocomial infections accounting for 23.3% of all bacterial isolates from different infection sites in the ICU. Serotyping of the clinical isolates and surveillance sample isolates from nurses′ hands showed serotype E as the most common serotype. Other serotypes of P. aeruginosa were isolated from environmental cultures such as sinks, floors, walls, tap water, etc. Conclusion: Study revealed a high prevalence of P. aeruginosa infections in the ICU attributed to cross transmission from patient to patient via hands of the nursing staff. Strict enforcement of infection control protocols is essential to minimize the disease burden.
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