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Turkish Journal of Medical Sciences 2015β-Lactamase production is considered one of the most important resistance mechanisms amongvirulent Pseudomonas aeruginosa isolates. The aim of this study was to compare... (Comparative Study)
Comparative Study
BACKGROUND/AIM
β-Lactamase production is considered one of the most important resistance mechanisms amongvirulent Pseudomonas aeruginosa isolates. The aim of this study was to compare the production and antimicrobial resistance patterns of some virulence factors in extended spectrum β-lactamase (ESβL)-producing and nonproducing P. aeruginosa clinical isolates.
MATERIALS AND METHODS
Out of 183 different clinical specimens, 104 Pseudomonas aeruginosa isolates were recovered. The isolates were screened for ESβL production using the double disk diffusion test and phenotypic confirmatory disk diffusion test. All isolates were tested for susceptibility to 25 antimicrobials, as well as for expression of various virulence factors including pigment, hemolysin, gelatinase, protease, lipase, rhamnolipids, biofilm, and cell surface hydrophobicity. The results of ESβL producers and honproducers were statistically compared.
RESULTS
All isolates showed a high frequency of multiple resistance to at least 14 and up to 25 of the tested antimicrobials. Nevertheless, most virulence factors were produced at higher rates in ESβL-producing than in ESβL-nonproducing Pseudomonas aeruginosa isolates.
CONCLUSION
The results of this study suggest a correlation between ESβL phenotype and the production of some factors that are reported to be involved in the virulence of P. aeruginosa.
Topics: Anti-Bacterial Agents; Humans; Microbial Sensitivity Tests; Phenotype; Pseudomonas Infections; Pseudomonas aeruginosa; Virulence Factors; beta-Lactamases
PubMed: 25790531
DOI: 10.3906/sag-1311-102 -
Medical Science Monitor : International... Apr 2016Pseudomonas aeruginosa infection remains a life-threatening complication after solid organ transplantation (SOT). We aimed to investigate the distribution and drug...
BACKGROUND
Pseudomonas aeruginosa infection remains a life-threatening complication after solid organ transplantation (SOT). We aimed to investigate the distribution and drug susceptibility of pathogens, and clinical characteristics of SOT recipients with Pseudomonas aeruginosa infections.
MATERIAL/METHODS
A total of 55 SOT recipients who developed 61 episodes of Pseudomonas aeruginosa infections between January 1, 2003 and July 31, 2015 were retrospectively analyzed. The distribution and the drug susceptibility of Pseudomonas aeruginosa were reviewed.
RESULTS
The most common site from which 61 Pseudomonas aeruginosa rods were isolated were the lungs (57.4%, n=37), followed by the blood (27.9%, n=17). There were 35, 18, and 9 recipients accompanied with a serum creatinine level of >1.5 mg/dL, lymphocyte count of <300/mm(3), and a serum albumin level of <30 g/L, respectively. Seven patients each presented with white blood cell count of >15,000/mm(3) and platelet count of <50,000/mm(3). There were 6 (10.9%) cases of septic shocks and 18 (32.7%) deaths. Antibiotic resistance rate of all Pseudomonas aeruginosa to 4 of 10 antibiotics investigated was more than 50%. Of these 61 Pseudomonas aeruginosa isolates, 47.5% were carbapenem-resistant. The rods were relatively sensitive to piperacillin-tazobactam, levofloxacin, amikacin, and cefoperazone-sulbactam (resistance rate <40%).
CONCLUSIONS
The clinical presentation of Pseudomonas aeruginosa infections included high body temperature, decreased platelet count, elevated white blood cell count, a high nosocomial origin and mortality, and onset in the late period after transplantation. According to our findings, piperacillin-tazobactam, levofloxacin, amikacin, and cefoperazone-sulbactam, alone or combination, are recommended to treat SOT recipients with Pseudomonas aeruginosa infections.
Topics: Adult; Anti-Bacterial Agents; Demography; Drug Resistance, Microbial; Female; Humans; Male; Pseudomonas Infections; Pseudomonas aeruginosa; Transplant Recipients; Transplantation
PubMed: 27045418
DOI: 10.12659/msm.896026 -
Scientific Reports Jan 2021While considered an extracellular pathogen, Pseudomonas aeruginosa has been reported to be engulfed by macrophages in cellular and animal models. However, the role of...
While considered an extracellular pathogen, Pseudomonas aeruginosa has been reported to be engulfed by macrophages in cellular and animal models. However, the role of macrophages in P. aeruginosa clearance in vivo remains poorly studied. The major outer membrane porin OprF has been recently shown to be involved in P. aeruginosa fate within cultured macrophages and analysis of an oprF mutant may thus provide insights to better understand the relevance of this intramacrophage stage during infection. In the present study, we investigated for the first time the virulence of a P. aeruginosa oprF mutant in a vertebrate model that harbors functional macrophages, the zebrafish (Danio rerio) embryo, which offers powerful tools to address macrophage-pathogen interactions. We established that P. aeruginosa oprF mutant is attenuated in zebrafish embryos in a macrophage-dependent manner. Visualization and quantification of P. aeruginosa bacteria phagocytosed by macrophages after injection into closed cavities suggested that the attenuated phenotype of oprF mutant is not linked to higher macrophage recruitment nor better phagocytosis than wild-type strain. Using cultured macrophages, we showed an intramacrophage survival defect of P. aeruginosa oprF mutant, which is correlated with elevated association of bacteria with acidic compartments. Notably, treatment of embryos with bafilomycin, an inhibitor of acidification, increased the sensibility of embryos towards both wild-type and oprF mutant, and partially suppressed the attenuation of oprF mutant. Taken together, this work supports zebrafish embryo as state-of-the-art model to address in vivo the relevance of P. aeruginosa intramacrophage stage. Our results highlight the contribution of macrophages in the clearance of P. aeruginosa during acute infection and suggest that OprF protects P. aeruginosa against macrophage clearance by avoiding bacterial elimination in acidified phagosomes.
Topics: Animals; Bacterial Proteins; Gene Expression Regulation, Bacterial; Macrophages; Pseudomonas aeruginosa; Zebrafish
PubMed: 33432030
DOI: 10.1038/s41598-020-79678-0 -
Scientific Reports Jul 2018Rapid evaporative ionisation mass spectrometry (REIMS) is a novel technique for the real-time analysis of biological material. It works by conducting an electrical... (Comparative Study)
Comparative Study
Rapid evaporative ionisation mass spectrometry (REIMS) is a novel technique for the real-time analysis of biological material. It works by conducting an electrical current through a sample, causing it to rapidly heat and evaporate, with the analyte containing vapour channelled to a mass spectrometer. It was used to characterise the metabolome of 45 Pseudomonas aeruginosa (P. aeruginosa) isolates from cystic fibrosis (CF) patients and compared to 80 non-CF P. aeruginosa. Phospholipids gave the highest signal intensity; 17 rhamnolipids and 18 quorum sensing molecules were detected, demonstrating that REIMS has potential for the study of virulence-related metabolites. P. aeruginosa isolates obtained from respiratory samples showed a higher diversity, which was attributed to the chronic nature of most respiratory infections. The analytical sensitivity of REIMS allowed the detection of a metabolome that could be used to classify individual P. aeruginosa isolates after repeated culturing with 81% accuracy, and an average 83% concordance with multilocus sequence typing. This study underpins the capacities of REIMS as a tool with clinical applications, such as metabolic phenotyping of the important CF pathogen P. aeruginosa, and highlights the potential of metabolic fingerprinting for fine scale characterisation at a sub-species level.
Topics: Bacterial Typing Techniques; Cystic Fibrosis; Humans; Metabolomics; Multilocus Sequence Typing; Phenotype; Pseudomonas Infections; Pseudomonas aeruginosa; Quorum Sensing; Sensitivity and Specificity; Spectrometry, Mass, Electrospray Ionization; Virulence
PubMed: 30026575
DOI: 10.1038/s41598-018-28665-7 -
PloS One 2013P. aeruginosa is known to cause acute cytotoxicity against various human and animal cells and tissues.
BACKGROUND
P. aeruginosa is known to cause acute cytotoxicity against various human and animal cells and tissues.
METHODOLOGY/FINDINGS
Intriguingly, however, in this study we noticed that while a low cell density inoculum of P. aeruginosa caused severe cytotoxicity against human lung tissue cell line A549, increasing the cell density of bacterial inoculum led to decreased cytotoxicity. Addition of the supernatants from high density bacterial culture to low cell density inoculum protected the human cells from bacterial cytotoxic damage, suggesting that P. aeruginosa may produce and accumulate an inhibitory molecule(s) counteracting its pathogenic infection. The inhibitor was purified from the stationary-phase culture supernatants of P. aeruginosa strain PAO1 using bioassay-guided high performance liquid chromatography (HPLC), and characterized to be phenylacetic acid (PAA) by mass spectrometry and nuclear magnetic resonance spectroscopy. Microarray analysis revealed that treatment of P. aeruginosa with PAA down-regulated the transcriptional expression of Type III secretion system (T3SS) genes and related regulatory genes including rsmA and vfr, which were confirmed by transcriptional and translational analysis.
CONCLUSIONS
Identification of bacterial metabolite PAA as a T3SS-specific inhibitor explains this intriguing inverse cell-density-dependent-cytotoxicity phenomenon as T3SS is known to be a key virulence factor associated with cytotoxicity and acute infection. The findings may provide useful clues for design and development of new strategies to combat this formidable bacterial pathogen.
Topics: Bacterial Proteins; Cell Line; Chromatography, High Pressure Liquid; Humans; Phenylacetates; Pseudomonas aeruginosa; Virulence
PubMed: 23555919
DOI: 10.1371/journal.pone.0060187 -
Journal of Applied Microbiology Apr 2016To establish the ability of the rhamnolipids biosurfactants from Pseudomonas aeruginosa, in the presence and absence of caprylic acid and ascorbic acid, to disrupt...
AIMS
To establish the ability of the rhamnolipids biosurfactants from Pseudomonas aeruginosa, in the presence and absence of caprylic acid and ascorbic acid, to disrupt bacterial biofilms, compared with the anionic alkyl sulphate surfactant Sodium dodecyl sulphate (SDS).
METHODS AND RESULTS
Pseudomonas aeruginosa ATCC 15442 biofilms were disrupted by rhamnolipids at concentrations between 0·5 and 0·4 g l(-1) and with SDS at 0·8 g l(-1) . The combination of rhamnolipids 0·4 g l(-1) and caprylic acid at 0·1 g l(-1) showed a remarkable effect on biofilm disruption and cell killing. After 30 min of treatment most of the biofilm was disrupted and cell viability was significantly reduced. Neither caprylic acid nor ascorbic acid has any effect on biofilm disruption at 0·1 g l(-1) . SDS is an effective antimicrobial agent; however, in the presence of caprylic acid its effect was neutralized.
CONCLUSIONS
The results show that rhamnolipids at low concentration in the presence of caprylic acid are promising molecules for inhibition/disruption of biofilms formed by Ps. aeruginosa ATCC 15442.
SIGNIFICANCE AND IMPACT OF THE STUDY
The disruption of biofilms has major significance in many industrial and domestic cleaning applications and in medical situations.
Topics: Biofilms; Glycolipids; Pseudomonas aeruginosa; Sodium Dodecyl Sulfate; Surface-Active Agents
PubMed: 26742560
DOI: 10.1111/jam.13049 -
PLoS Pathogens Sep 2008When environmental conditions deteriorate and become inhospitable, generic survival strategies for populations of bacteria may be to enter a dormant state that slows...
When environmental conditions deteriorate and become inhospitable, generic survival strategies for populations of bacteria may be to enter a dormant state that slows down metabolism, to develop a general tolerance to hostile parameters that characterize the habitat, and to impose a regime to eliminate damaged members. Here, we provide evidence that the pseudomonas quinolone signal (PQS) mediates induction of all of these phenotypes. For individual cells, PQS, an interbacterial signaling molecule of Pseudomonas aeruginosa, has both deleterious and beneficial activities: on the one hand, it acts as a pro-oxidant and sensitizes the bacteria towards oxidative and other stresses and, on the other, it efficiently induces a protective anti-oxidative stress response. We propose that this dual function fragments populations into less and more stress tolerant members which respond differentially to developing stresses in deteriorating habitats. This suggests that a little poison may be generically beneficial to populations, in promoting survival of the fittest, and in contributing to bacterial multi-cellular behavior. It further identifies PQS as an essential mediator of the shaping of the population structure of Pseudomonas and of its response to and survival in hostile environmental conditions.
Topics: 4-Quinolones; Antioxidants; Oxidants; Pseudomonas aeruginosa; Quinolones; Quorum Sensing; Reactive Oxygen Species; Selection, Genetic
PubMed: 18818733
DOI: 10.1371/journal.ppat.1000166 -
Scientific Reports Mar 2021Pseudomonas aeruginosa uses quorum sensing (QS) to modulate the expression of several virulence factors that enable it to establish severe infections. The QS system in...
Pseudomonas aeruginosa uses quorum sensing (QS) to modulate the expression of several virulence factors that enable it to establish severe infections. The QS system in P. aeruginosa is complex, intricate and is dominated by two main N-acyl-homoserine lactone circuits, LasRI and RhlRI. These two QS systems work in a hierarchical fashion with LasRI at the top, directly regulating RhlRI. Together these QS circuits regulate several virulence associated genes, metabolites, and enzymes in P. aeruginosa. Paradoxically, LasR mutants are frequently isolated from chronic P. aeruginosa infections, typically among cystic fibrosis (CF) patients. This suggests P. aeruginosa can undergo significant evolutionary pathoadaptation to persist in long term chronic infections. In contrast, mutations in the RhlRI system are less common. Here, we have isolated a clinical strain of P. aeruginosa from a CF patient that has deleted the transcriptional regulator RhlR entirely. Whole genome sequencing shows the rhlR locus is deleted in PA80 alongside a few non-synonymous mutations in virulence factors including protease lasA and rhamnolipid rhlA, rhlB, rhlC. Importantly we did not observe any mutations in the LasRI QS system. PA80 does not appear to have an accumulation of mutations typically associated with several hallmark pathoadaptive genes (i.e., mexT, mucA, algR, rpoN, exsS, ampR). Whole genome comparisons show that P. aeruginosa strain PA80 is closely related to the hypervirulent Liverpool epidemic strain (LES) LESB58. PA80 also contains several genomic islands (GI's) encoding virulence and/or resistance determinants homologous to LESB58. To further understand the effect of these mutations in PA80 QS regulatory and virulence associated genes, we compared transcriptional expression of genes and phenotypic effects with isogenic mutants in the genetic reference strain PAO1. In PAO1, we show that deletion of rhlR has a much more significant impact on the expression of a wide range of virulence associated factors rather than deletion of lasR. In PA80, no QS regulatory genes were expressed, which we attribute to the inactivation of the RhlRI QS system by deletion of rhlR and mutation of rhlI. This study demonstrates that inactivation of the LasRI system does not impact RhlRI regulated virulence factors. PA80 has bypassed the common pathoadaptive mutations observed in LasR by targeting the RhlRI system. This suggests that RhlRI is a significant target for the long-term persistence of P. aeruginosa in chronic CF patients. This raises important questions in targeting QS systems for therapeutic interventions.
Topics: Bacterial Proteins; Cystic Fibrosis; Gene Expression Regulation, Bacterial; Genetic Variation; Genomics; Humans; Mutation; Phylogeny; Pseudomonas aeruginosa; Quorum Sensing; Virulence Factors
PubMed: 33707533
DOI: 10.1038/s41598-021-85100-0 -
Biocontrol Science Dec 2009Pseudomonas aeruginosa strains were isolated from 45 of 370 (12.2%) cockroaches captured in hospitals. By cockroach species, the bacterial strains were isolated from 39...
Pseudomonas aeruginosa strains were isolated from 45 of 370 (12.2%) cockroaches captured in hospitals. By cockroach species, the bacterial strains were isolated from 39 of 181 (21.5%) Periplaneta fuliginosa and 6 of 183 (3.3%) Blattella germanica, showing a significant difference (p<0.01). Many P. aeruginosa-carrying cockroaches inhabited locker rooms (66.7%) and kitchens (17.8%). In terms of serotyping, many isolates were typed into groups A, G, and B. In drug sensitivity tests, strains showed the highest sensitivity to ciprofloxacin with an MIC90 of 0.25 microg/ml, followed by 2 microg/ml meropenem, and 4 microg/ml ceftazidime, gentamicin, and ofloxacin. In contrast, many strains were resistant to cefotaxime and minocycline, accounting for 86.7% of all resistant strains. However, there was no multidrug-resistant P. aeruginosa strain, and all strains were negative for the metallo-beta-lactamase gene (IMP-1 and VIM-2). These findings suggested that cockroach-derived P. aeruginosa may contaminate hospital environments, for which the control of disease-carrying insects in hospitals is important.
Topics: Animals; Cockroaches; Hospitals; Japan; Microbial Sensitivity Tests; Polymerase Chain Reaction; Pseudomonas Infections; Pseudomonas aeruginosa
PubMed: 20055220
DOI: 10.4265/bio.14.155 -
Microbiology and Immunology 2007Pseudomonas aeruginosa is a key pathogen of nosocomial infection, and causes persistent infection in patients with specific diseases like cystic fibrosis (CF). It has...
Pseudomonas aeruginosa is a key pathogen of nosocomial infection, and causes persistent infection in patients with specific diseases like cystic fibrosis (CF). It has been reported that patients affected with CF discharge, at a high frequency, small colony variants with high adherence ability. In routine laboratory testing, we found atypical small and rough type (SR) colony variants of P. aeruginosa. The SRs and the counterpart wild type (WT) colonies showed similar biochemical features, antimicrobial susceptibilities, pulsed-field gel electrophoresis (PFGE) profiles, serotypes, and twitching motilities. The biofilm formation abilities of all the SR colonies, however, were extremely elevated as compared to those of the counterpart WT colonies. The frequency of SR-positive patients was 3.1% of the P. aeruginosa-positive inpatients (5/160), and that of the SR isolates was 0.6% of the P. aeruginosa strains (6/970) isolated in our laboratory over a period of 6 months. The SR-positive patients did not have any common disease or particular antibiotics treatment. The PFGE profiles showed that the SRs and the counterpart WTs were identical to each other, and also that three of the five SR/WT pairs were clonally similar. The three pairs were recovered from the feces, urine, and endotracheal secretion, respectively, of three patients hospitalized in two distinct wards. The results suggest that P. aeruginosa spontaneously produced highly adherent SR colonies in hospitalized patients, and these colonies may tend to spread in a hospital.
Topics: Bacterial Adhesion; Bacterial Typing Techniques; Biofilms; Cross Infection; Electrophoresis, Gel, Pulsed-Field; Hospitalization; Pseudomonas Infections; Pseudomonas aeruginosa; RNA, Ribosomal, 16S; Sequence Analysis, DNA
PubMed: 17951982
DOI: 10.1111/j.1348-0421.2007.tb03989.x