scholarly journals Phenotypic stress response of Pseudomonas aeruginosa following culture in water microcosms

2012 ◽  
Vol 10 (1) ◽  
pp. 130-139 ◽  
Author(s):  
Jihane Cheriaa ◽  
Mahmoud Rouabhia ◽  
Makaoui Maatallah ◽  
Amina Bakhrouf
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Environmental Changes ◽  
Starvation Period ◽  
Wild Type ◽  
Beta Lactam ◽  
Antibiotic Resistant ◽  
Aquatic Microcosms ◽  
Beta Lactam Antibiotics ◽  
In The Wild ◽  
Human Infections

The purpose of the present study was to explore the potential behavioural changes of Pseudomonas aeruginosa following growth in different aquatic environmental conditions. To achieve this, P. aeruginosa was cultured in various water microcosms for 12 months under fixed (pH, nutrients and temperature) factors. P. aeruginosa responses to these conditions were investigated using colony morphotype, biochemical and enzymatic characterisation, pyocin typing, serotyping, sensitivity to different classes of antibiotics and molecular identification. Results show that starvation in water microcosms lead to unusual phenotypes. Of interest is that the pyocin changed from 24/n in the wild type to 83/a following culture in the water microcosms, and the serotype changed from O6 in the wild type to O1 in microcosm-cultured P. aeruginosa. Furthermore, the starvation period in various aquatic microcosms enhanced the resistance of P. aeruginosa against beta-lactam antibiotics. Compared to the other aquatic environments, the seawater microcosm produced the greatest amount of variations in P. aeruginosa. Overall, data demonstrated a high adaptability of P. aeruginosa to environmental changes. This may explain the unusual antibiotic-resistant phenotypes belonging to P. aeruginosa species, and their capacity for spreading that leads to human infections.

scholarly journals RpoS-Dependent Stress Response and Exoenzyme Production in Vibrio vulnificus

2003 ◽  
Vol 69 (10) ◽  
pp. 6114-6120 ◽  
Author(s):  
A. Hülsmann ◽  
T. M. Rosche ◽  
I.-S. Kong ◽  
H. M. Hassan ◽  
D. M. Beam ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stress Response ◽  
Mutant Strain ◽  
Environmental Changes ◽  
Vibrio Vulnificus ◽  
High Sensitivity ◽  
Striking Difference ◽  
Wild Type ◽  
Hydrolytic Activities ◽  
In The Wild

ABSTRACT Vibrio vulnificus is an estuarine bacterium capable of causing rapidly fatal infections through both ingestion and wound infection. Like other opportunistic pathogens, V. vulnificus must adapt to potentially stressful environmental changes while living freely in seawater, upon colonization of the oyster gut, and upon infection of such diverse hosts as humans and eels. In order to begin to understand the ability of V. vulnificus to respond to such stresses, we examined the role of the alternate sigma factor RpoS, which is important in stress response and virulence in many pathogens. An rpoS mutant of V. vulnificus strain C7184o was constructed by homologous recombination. The mutant strain exhibited a decreased ability to survive diverse environmental stresses, including exposure to hydrogen peroxide, hyperosmolarity, and acidic conditions. The most striking difference was a high sensitivity of the mutant to hydrogen peroxide. Albuminase, caseinase, and elastase activity were detected in the wild type but not in the mutant strain, and an additional two hydrolytic activities (collagenase and gelatinase) were reduced in the mutant strain compared to the wild type. Additionally, the motility of the rpoS mutant was severely diminished. Overall, these studies suggest that rpoS in V. vulnificus is important for adaptation to environmental changes and may have a role in virulence.

scholarly journals Growing Menace of Antibacterial Resistance in Clinical Isolates ofPseudomonas aeruginosain Nepal: An Insight of Beta-Lactamase Production

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Shamshul Ansari ◽  
Rabindra Dhital ◽  
Sony Shrestha ◽  
Sangita Thapa ◽  
Ram Puri ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Opportunistic Pathogen ◽  
Resistance Rate ◽  
Diffusion Method ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Beta Lactam Antibiotics ◽  
Microbiological Methods ◽  
Immunosuppressed Patients

Introduction. Pseudomonas aeruginosais the most frequently isolated organism as it acts as the opportunistic pathogen and can cause infections in immunosuppressed patients. The production of different types of beta-lactamases renders this organism resistant to many commonly used antimicrobials. Therefore, the aim of this study was to document the antibiotic resistance rate inPseudomonas aeruginosaisolated from different clinical specimens.Methods. Pseudomonas aeruginosarecovered was identified by standard microbiological methods. Antibiotic susceptibility testing was performed by modified Kirby-Bauer disc diffusion method following Clinical and Laboratory Standard Institute (CLSI) guidelines and all the suspected isolates were tested for the production of ESBLs, MBLs, and AmpC.Results.Out of total (178) isolates, 83.1% were recovered from the inpatient department (IPD). Majority of the isolates mediated resistance towards the beta-lactam antibiotics, while nearly half of the isolates were resistant to ciprofloxacin. Most of the aminoglycosides used showed resistance rate up to 75% but amikacin proved to be better option. No resistance to polymyxin was observed. ESBLs, MBLs, and AmpC mediated resistance was seen in 33.1%, 30.9%, and 15.7% isolates, respectively.Conclusions. Antibiotic resistance rate and beta-lactamase mediated resistance were high. Thus, regular surveillance of drug resistance is of utmost importance.

scholarly journals Beta-lactam allergy in the paediatric population

2020 ◽  
Vol 25 (1) ◽  
pp. 62-62 ◽  
Author(s):  
Tiffany Wong ◽  
Adelle Atkinson ◽  
Geert t’Jong ◽  
Michael J Rieder ◽  
Edmond S Chan ◽  
...  
Keyword(s):  
Paediatric Population ◽  
Outpatient Setting ◽  
Stevens Johnson Syndrome ◽  
Beta Lactam ◽  
Antibiotic Resistant ◽  
Beta Lactam Antibiotics ◽  
Johnson Syndrome ◽  
Ige Mediated ◽  
Systemic Symptoms ◽  
Exanthematous Pustulosis

Abstract Beta-lactam allergy is commonly diagnosed in paediatric patients, but over 90% of individuals reporting this allergy are able to tolerate the medications prescribed after evaluation by an allergist. Beta-lactam allergy labels are associated with negative clinical and administrative outcomes, including use of less desirable alternative antibiotics, longer hospitalizations, increasing antibiotic-resistant infections, and greater medical costs. Also, children with true IgE-mediated allergy to penicillin medications are often advised to avoid all beta-lactam antibiotics, including cephalosporins, which is likely unnecessary in greater than 97% of those reporting penicillin allergies. Most patients can be safely treated with penicillin or amoxicillin if they do not have a history compatible with IgE-mediated or systemic, delayed reactions such as Stevens-Johnson syndrome (SJS), serum sickness-like reactions, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, or acute generalized exanthematous pustulosis (AGEP). Guidance is provided on how to stratify risk of beta-lactam allergy, and on test dosing and monitoring in the outpatient setting for patients deemed low risk. Guidance for patients at higher risk of beta-lactam allergy includes criteria for appropriate referral to allergists and the use of alternative antimicrobials, such as cephalosporins, while awaiting specialist assessment.

scholarly journals A TEM-derived extended-spectrum beta-lactamase in Pseudomonas aeruginosa.

1996 ◽  
Vol 40 (11) ◽  
pp. 2488-2493 ◽  
Author(s):  
P Mugnier ◽  
P Dubrous ◽  
I Casin ◽  
G Arlet ◽  
E Collatz
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clinical Strain ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Aminoglycoside Resistance ◽  
Double Mutation ◽  
Extended Spectrum Beta Lactamase ◽  
Beta Lactam Antibiotics ◽  
Extended Spectrum ◽  
High Level

A clinical strain of Pseudomonas aeruginosa, PAe1100, was found to be resistant to all antipseudomonal beta-lactam antibiotics and to aminoglycosides, including gentamicin, amikacin, and isepamicin. PAe1100 produced two beta-lactamases, TEM-2 (pI 5.6) and a novel, TEM-derived extended-spectrum beta-lactamase called TEM-42 (pI 5.8), susceptible to inhibition by clavulanate, sulbactam, and tazobactam. Both enzymes, as well as the aminoglycoside resistance which resulted from AAC(3)-IIa and AAC(6')-I production, were encoded by an 18-kb nonconjugative plasmid, pLRM1, that could be transferred to Escherichia coli by transformation. The gene coding for TEM-42 had four mutations that led to as many amino acid substitutions with respect to TEM-2: Val for Ala at position 42 (Ala42), Ser for Gly238, Lys for Glu240, and Met for Thr265 (Ambler numbering). The double mutation Ser for Gly238 and Lys for Glu240, which has so far only been described in SHV-type but not TEM-type enzymes, conferred concomitant high-level resistance to cefotaxime and ceftazidime. The novel, TEM-derived extended-spectrum beta-lactamase appears to be the first of its class to be described in P. aeruginosa.

scholarly journals The Atypical Response Regulator AtvR Is a New Player in Pseudomonas aeruginosa Response to Hypoxia and Virulence

2017 ◽  
Vol 85 (8) ◽  
Author(s):  
Gilberto Hideo Kaihami ◽  
Leandro Carvalho Dantas Breda ◽  
José Roberto Fogaça de Almeida ◽  
Thays de Oliveira Pereira ◽  
Gianlucca Gonçalves Nicastro ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Strain ◽  
Wild Type Strain ◽  
Environmental Changes ◽  
Response Regulator ◽  
Classical Pathway ◽  
Wild Type ◽  
Macrophage Infection ◽  
Content Type ◽  
Successful Infection

ABSTRACT Two-component systems are widespread in bacteria, allowing adaptation to environmental changes. The classical pathway is composed of a histidine kinase that phosphorylates an aspartate residue in the cognate response regulator (RR). RRs lacking the phosphorylatable aspartate also occur, but their function and contribution during host-pathogen interactions are poorly characterized. AtvR (PA14_26570) is the only atypical response regulator with a DNA-binding domain in the opportunistic pathogen Pseudomonas aeruginosa. Macrophage infection with the atvR mutant strain resulted in higher levels of tumor necrosis factor alpha secretion as well as increased bacterial clearance compared to those for macrophages infected with the wild-type strain. In an acute pneumonia model, mice infected with the atvR mutant presented increased amounts of proinflammatory cytokines, increased neutrophil recruitment to the lungs, reductions in bacterial burdens, and higher survival rates in comparison with the findings for mice infected with the wild-type strain. Further, several genes involved in hypoxia/anoxia adaptation were upregulated upon atvR overexpression, as seen by high-throughput transcriptome sequencing (RNA-Seq) analysis. In addition, atvR was more expressed in hypoxia in the presence of nitrate and required for full expression of nitrate reductase genes, promoting bacterial growth under this condition. Thus, AtvR would be crucial for successful infection, aiding P. aeruginosa survival under conditions of low oxygen tension in the host. Taken together, our data demonstrate that the atypical response regulator AtvR is part of the repertoire of transcriptional regulators involved in the lifestyle switch from aerobic to anaerobic conditions. This finding increases the complexity of regulation of one of the central metabolic pathways that contributes to Pseudomonas ubiquity and versatility.

scholarly journals Overexpression of the MexEF-OprN Multidrug Efflux System Affects Cell-to-Cell Signaling in Pseudomonas aeruginosa

2001 ◽  
Vol 183 (18) ◽  
pp. 5213-5222 ◽  
Author(s):  
Thilo Köhler ◽  
Christian van Delden ◽  
Lasta Kocjancic Curty ◽  
Mehri Michea Hamzehpour ◽  
Jean-Claude Pechere
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Homoserine Lactone ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Efflux System ◽  
Sensing Systems ◽  
In The Wild ◽  
Type Mutant ◽  
Regulator Genes

ABSTRACT Intrinsic and acquired antibiotic resistance of the nosocomial pathogen Pseudomonas aeruginosa is mediated mainly by the expression of several efflux pumps of broad substrate specificity. Here we report that nfxC type mutants, overexpressing the MexEF-OprN efflux system, produce lower levels of extracellular virulence factors than the susceptible wild type. These include pyocyanin, elastase, and rhamnolipids, three factors controlled by the las and rhl quorum-sensing systems of P. aeruginosa. In agreement with these observations are the decreased transcription of the elastase genelasB and the rhamnosyltransferase genesrhlAB measured in nfxC type mutants. Expression of the lasR and rhlR regulator genes was not affected in the nfxC type mutant. In contrast, transcription of the C4-homoserine lactone (C4-HSL) autoinducer synthase gene rhlI was reduced by 50% in the nfxC type mutant relative to that in the wild type. This correlates with a similar decrease in C4-HSL levels detected in supernatants of the nfxC type mutant. Transcription of an rhlAB-lacZ fusion could be partially restored by the addition of synthetic C4-HSL andPseudomonas quinolone signal (PQS). It is proposed that the MexEF-OprN efflux pump affects intracellular PQS levels.

scholarly journals Adaptation of Aerobically Growing Pseudomonas aeruginosa to Copper Starvation

2008 ◽  
Vol 190 (20) ◽  
pp. 6706-6717 ◽  
Author(s):  
Emanuela Frangipani ◽  
Vera I. Slaveykova ◽  
Cornelia Reimmann ◽  
Dieter Haas
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Opportunistic Pathogen ◽  
Cellular Respiration ◽  
Wild Type ◽  
Respiratory Enzymes ◽  
Terminal Oxidases ◽  
Copper Status ◽  
In The Wild ◽  
Quadruple Mutant ◽  
Heme Copper Oxidases

ABSTRACT Restricted bioavailability of copper in certain environments can interfere with cellular respiration because copper is an essential cofactor of most terminal oxidases. The global response of the metabolically versatile bacterium and opportunistic pathogen Pseudomonas aeruginosa to copper limitation was assessed under aerobic conditions. Expression of cioAB (encoding an alternative, copper-independent, cyanide-resistant ubiquinol oxidase) was upregulated, whereas numerous iron uptake functions (including the siderophores pyoverdine and pyochelin) were expressed at reduced levels, presumably reflecting a lower demand for iron by respiratory enzymes. Wild-type P. aeruginosa was able to grow aerobically in a defined glucose medium depleted of copper, whereas a cioAB mutant did not grow. Thus, P. aeruginosa relies on the CioAB enzyme to cope with severe copper deprivation. A quadruple cyo cco1 cco2 cox mutant, which was deleted for all known heme-copper terminal oxidases of P. aeruginosa, grew aerobically, albeit more slowly than did the wild type, indicating that the CioAB enzyme is capable of energy conservation. However, the expression of a cioA′-′lacZ fusion was less dependent on the copper status in the quadruple mutant than in the wild type, suggesting that copper availability might affect cioAB expression indirectly, via the function of the heme-copper oxidases.

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