Interrelationships between colonies, biofilms, and planktonic cells of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a gram-negative bacterium and an opportunistic human pathogen that causes chronic infections in immunocompromised individuals. These infections are hard to treat, partly due to the high intrinsic resistance of the bacterium to clinically used antibiotics and partly due to the formation of antibiotic-tolerant biofilms. The three most common ways of growing bacteria in vitro are as planktonic cultures, colonies on agar plates, and biofilms in continuous-flow systems. Biofilms are known to express genes different from those of planktonic cells, and biofilm cells are generally believed to closely resemble planktonic cells in stationary phase. However, few, if any, studies have examined global gene expression in colonies. We used a proteomic approach to investigate the interrelationships between planktonic cells, colonies, and biofilms under comparable conditions. Our results show that protein profiles in colonies resemble those of planktonic cells. Furthermore, contrary to what has been reported previously, the protein profiles of biofilms were found to more closely resemble those of exponentially growing planktonic cells than those of planktonic cells in the stationary phase. These findings raise some intriguing questions about the true nature of biofilms.     

Expression of the argF gene of Pseudomonas aeruginosa in Pseudomonas aeruginosa, Pseudomonas putida, and Escherichia coli

R' plasmids carrying argF genes from Pseudomonas aeruginosa strains PAO and PAC were transferred to Pseudomonas putida argF and Escherichia coli argF strains. Expression in P. putida was similar to that in P. aeruginosa and was repressed by exogenous arginine. Expression in E. coli was 2 to 4% of that in P. aeruginosa. Exogenous arginine had no effect, and there were no significant differences between argR' and argR strains of E. coli in this respect.     

Synergism between Chlorhexidine and Polymyxins against Pseudomonas aeruginosa

Chlorhexidine acts synergistically with the polymyxins B and E causing increased and rapid release of cell contents from Pseudomonas aeruginosa. While the polymyxin target molecule is phospholipid, evidence is provided for the proposal that the primary target for Chlorhexidine action is a protein component of the cytoplasmic membrane.     

Interspecies communication between Burkholderia cepacia and Pseudomonas aeruginosa

Burkholderia cepacia and Pseudomonas aeruginosa are opportunistic pathogens that commonly cause pulmonary infections in cystic fibrosis patients and occasionally co-infect patients' lungs. Both organisms possess quorum-sensing systems dependent on N-acyl homoserine lactone (N-acyl-HSL). Cross-feeding assays demonstrated that P. aeruginosa and B. cepacia were able to utilize heterologous N-acyl-HSL signaling molecules. The ability of quorum-sensing genes from one species to complement the respective quorum-sensing mutations in the heterologous species was also examined. These studies suggest that B. cepacia CepR can use N-acyl-HSLs synthesized by RhlI and LasI and that P. aeruginosa LasR and RhlR can use N-acyl-HSLs synthesized by CepI. It is possible that a mixed bacterial population of B. cepacia and P. aeruginosa can coordinately regulate some of their virulence factors and influence the progression of lung disease due to infection with these organisms.     

铜绿假单胞菌和白假丝酵母的跨界相互作用

铜绿假单胞菌和白假丝酵母(又称白念珠菌)这两种条件致病菌可共存于人体。两者间存在复杂的相互关系,即跨界相互作用。铜绿假单胞菌抑制白念珠菌形态转换,抑制其生物膜形成并毒杀其菌丝;白念珠菌则抑制铜绿假单胞菌绿脓素形成并抑制其丛集运动。跨界相互作用可能存在3种机制:信号转导通路、生物膜和毒力因子。铜绿假单胞菌通过信号分子N-3-氧代十二烷酰-L-同型丝氨酸内酯(3-oxo-C12-HSL)抑制白念珠菌形态转换,而白念珠菌通过信号分子法呢醇抑制铜绿假单胞菌绿脓素生成和丛集运动,即存在信号分子介导的跨界相互作用。跨界相互作用影响铜绿假单胞菌和白念珠菌各自的致病性。如能充分利用跨界相互作用,将有助于优化治疗的选择。     

PseudoCyc,a pathway-genome database for Pseudomonas aeruginosa

A pathway-genome database (PGDB) describes the entire genome of an organism, as well as its biochemical pathways, reactions, and enzymes. Our PathoLogic software can generate a PGDB from an annotated genome of an organism, predicting the metabolic reactions and pathways corresponding to the enzymes present in the annotation. We have used PathoLogic to generate a PGDB for PSEUDOMONAS AERUGINOSA, strain PAO1, called 'PseudoCyc', which includes 139 predicted pathways and 800 predicted reactions involving 623 chemical species and 718 enzymes. Analysis of the PathoLogic predictions of arginine metabolism and the beta-ketoadipate pathway, which are landmark pathways in P. AERUGINOSA, showed that they were for the most part correctly predicted. These studies also provided possible locations for two genes involved in the beta-ketoadipate pathway, PCAI and PCAJ, which are missing from the PAO1 annotation. PseudoCyc adds an extended dimension to the genome of P. AERUGINOSA, providing researchers with a helpful tool for the analysis of the genomic, proteomic, and metabolic information of the organism. The finding of the probable location of the PCAI and PCAJ genes is but one example of the discoveries facilitated by such a PGDB. PseudoCyc, along with PGDBs for 12 other organisms, is available at http://BioCyc.org/.     

R Plasmids R91 and R91a from Pseudomonas aeruginosa Share Only the Gene for Carbenicillin Resistance

Plasmid R91a of Pseudomonas aeruginosa strain 9169 is homologous with RP1. Plasmid R91 carried by the same strain is related in the Tn1 region but is otherwise unrelated to R91a.     

Effectiveness of a polyvalent corpuscular Pseudomonas aeruginosa vaccine, antibiotics and their combinations in experimental chronic Pseudomonas aeruginosa infection

The data on the development of the experimental model of P. aeruginosa chronic infection in mice, produced by their intraperitoneal inoculation with the infective agent, and on the study of the properties of this model are presented. The model has been used in the experimental study of the preventive action of P. aeruginosa polyvalent corpuscular vaccine. The comparative study, carried out with the use of the proposed model, has been made with a view to evaluating the effectiveness of different methods for the treatment of P. aeruginosa chronic septic infection by means of antibiotics (polymixin B and tobramycin), P. aeruginosa polyvalent corpuscular vaccine and their combination. The combined use of this vaccine with antibiotics (polymixin B or tobramycin) has proved to give the most pronounced curative effect with respect to P. aeruginosa chronic infection.     

Association between Alcohol, Smoking and HLA-DQA1*0201 Genotype in Psoriasis

Psoriasis is a common chronic disease characterizedby erythema and scaling plaques. Although the disease isnot fatal, it detrimentally affects the life-quality of thesufferer, but no effective curative therapy has beenestablished. Up to now, the pathogene…     

Inverse Association between Obesity Predisposing FTO Genotype and Completed Suicide

The A allele of rs9939609 in the FTO gene predisposes to increased body mass index (BMI) and obesity. Recently we showed an inverse association between the obesity related A allele of rs9939609 and alcohol dependence which was replicated by others. Since this finding raises a possibility that FTO may be associated with other psychiatric phenotypes, we aimed to examine association of rs9939609 with completed suicide. We genotyped rs9939609 in 912 suicide victims and 733 controls using TaqMan approach. We observed an inverse association between suicide and the rs9939609 A allele (OR = 0.80, P = 0.002, P_cor = 0.006) with genotype distribution suggesting a co-dominant effect. Given the link between alcoholism and suicide under influence of alcohol reported in Polish population, confounding by alcohol addiction was unlikely due to apparently similar effect size among cases who were under influence of ethanol at the time of death (OR = 0.76, P = 0.003, N = 361) and those who were not (OR = 0.80, P = 0.007, N = 469). The search for genotype-phenotype correlations did not show significant results. In conclusion, our study proves that there is an inverse association between rs9939609 polymorphism in FTO gene and completed suicide which is independent from association between FTO and alcohol addiction.     

铜绿假单胞菌生物被膜与宿主免疫的关系

铜绿假单胞菌(Pseudomonas aeruginosa,P.aeruginosa)是一种常见的革兰阴性条件致病菌,能引起严重的院内感染,可从支气管扩张、肺囊性纤维化(CF)等患者体内分离。机体免疫系统可以通过识别不同的病原体相关分子模式(PAMPs)来抵御P.aeruginosa的感染,但P.aeruginosa生物被膜(BF)的形成可以导致这些成分被遮蔽从而引起免疫逃逸,导致疾病的迁延难愈。BF是一种与游离细菌相对立的生活方式,能帮助细菌有效适应外部环境,其可以通过藻酸盐的屏障作用,抵抗吞噬细胞的吞噬,干扰多核白细胞(PMNs)的激活,从而逃避宿主免疫。研究P.aeruginosa-BF的免疫逃逸机制,发现有效清除P.aeruginosa-BF的方法,从而为临床治疗P.aeruginosa引起的感染性疾病提供科学依据。现以P.aeruginosa为例对近年来国内外BF的免疫逃逸机制的研究进展进行综述。     

Characterization of the interaction between liposomal formulations and Pseudomonas aeruginosa

The interactions between three liposomal formulations and Pseudomonas aeruginosa cells were evaluated by a lipid mixing assay and electron paramagnetic resonance (EPR) spectroscopy. The effect of the bacteria on the liposomal phase characteristics, the release of the liposomes’ content, and the uptake rate of gentamicin by bacteria were monitored as a function of time, using EPR spectroscopy. The [16-DSA uptake]_Total from DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) liposomes reached 93?±?12% over a 3-hour assay period, of which 9% crossed the bacterial inner membrane. A small amount of 16-DSA uptake from DPPC/Chol (cholesterol) vesicles was found throughout the 3-hour period of time. Although DPPC/DMPG (dimyristoylphosphatidylglycerol) vesicles showed a smaller value of [16-DSA uptake]_Total with respect to that of DPPC vesicles, they appeared to be effective in disrupting the bacterial membrane, resulting in a greater accumulation of 16-DSA inside the inner membrane. Exposure to bacteria caused the DPPC/Chol, DPPC, and DPPC/DMPG formulations to release 4.6?±?1.5, 17.6?±?1.2, and 34?±?3.7% of their content, respectively. Time-dependent fluid regions were developed within the vesicles when mixed with bacteria, and their growth over time depended on liposomal formulations. Incubation of gentamicin with bacteria for 3 hours resulted in 87?±?3% of the drug crossing the bacterial inner membrane. In conclusion, interaction between the liposome drug carriers and the bacterial cells result in vesicle fusion, disruption of the bacterial membrane, release of the liposomal content in the close vicinity of the bacteria cells, and the subsequent intracellular uptake of the released liposomal content.