Marta Putrinš

• PhD
• Researcher at University of Tartu

Invasive salmonellosis caused by Salmonella enterica subspecies affects millions of people every year, mostly children from low-income countries, and is associated with a high mortality rate. Azithromycin is used to treat invasive salmonellosis resistant to first-line drugs despite conflicting effective concentrations in vitro and achievable serum...

Azithromycin is used to treat invasive salmonellosis, despite conflicting effective concentrations in vitro and in vivo. Resistance of Salmonella enterica to azithromycin is increasing. We demonstrate that nanomotion technology can be used for rapid phenotypic testing of Salmonella's susceptibility to azithromycin. Nanomotion changes under various...

Electrospun (ES) fibrous nanomaterials have been widely investigated as novel biomaterials. These biomaterials have to be safe and biocompatible; hence, they need to be tested for cytotoxicity before being administered to patients. The aim of this study was to develop a suitable and biorelevant in vitro cytotoxicity assay for ES biomaterials (e.g....

We developed a reporter system based on simultaneous expression of two fluorescent proteins: GFP as a reporter of the capacity of protein synthesis and mutated mScarlet-I as a reporter of translational errors. Because of the unique stop codons or frameshift mutations introduced into the mScarlet-I gene, red fluorescence was produced only after a mi...

Conventional wound infection treatments neither actively promote wound healing nor address the growing problem of antibacterial resistance. Antimicrobial peptides (AMPs) are natural defense molecules, released from host cells, which may be rapidly bactericidal, modulate host-immune responses, and/or act as endogenous mediators for wound healing. Ho...

We developed a reporter system based on simultaneous expression of two fluorescent proteins: GFP as a reporter of the capacity of protein synthesis and mutated mScarlet-I as a reporter of translational errors. Because of the unique stop codons or frameshift mutations introduced into the mScarlet-I gene, red fluorescence was produced only after a mi...

Increasing evidence suggests that the chronicity of wounds is associated with the presence of bacterial biofilms. Therefore, novel wound care products are being developed, which can inhibit biofilm formation and/or treat already formed biofilms. A lack of standardized assays for the analysis of such novel antibacterial drug delivery systems enhance...

Azithromycin is a clinically important drug for treating invasive salmonellosis despite poor activity in laboratory assays for MIC. Addition of the main buffer in blood, bicarbonate, has been proposed for more physiologically relevant and more predictive testing conditions. However, we show here that bicarbonate-triggered lowering of azithromycin M...

Uropathogenic Escherichia coli (UPEC), the major causative agent of urinary tract infections, is able to invade different types of host cells. To compare the pharmacodynamic properties of antibiotics against intra- and extracellular UPEC, an in vitro model of intracellular infection was established in J774 mouse macrophages infected by the UPEC str...

Electrospun fiber scaffolds have a huge potential for the successful treatment of infected wounds based on their unique properties. Although several studies report novel drug-loaded electrospun fiber-based biomaterials, many of these do not provide information on their interactions with eukaryotic and bacterial cells. The main aim of this study was...

Many bacterial pathogens can permanently colonize their host and establish either chronic or recurrent infections that the immune system and antimicrobial therapies fail to eradicate. Antibiotic persisters (persister cells) are believed to be among the factors that make these infections challenging. Persisters are subpopulations of bacteria which s...

By definition, persister cells must resume growth after the bactericidal treatment. Growth resumption can also lead to the reoccurrence of the infections and is, therefore, the reason why persisters are considered clinically important. Furthermore, treatments that enforce the dormant bacteria to resuscitate during the antibiotic treatment might bec...

New strategies are continuously sought for the treatment of skin and wound infections due to increased problems with non-healing wounds. Electrospun nanofiber mats with antibacterial agents as drug delivery systems provide opportunities for the eradication of bacterial infections as well as wound healing. Antibacterial activities of such mats are d...

Microbiological quality of a pharmaceutical product is an essential requirement ensuring patient safety, thus effective sterilization/disinfection methods need to be found. The aim of this study was to evaluate the efficacy of different sterilization/disinfection methods on drug-loaded electrospun matrices and the impact of these treatments on the...

Within the larger ABC superfamily of ATPases, ABCF family members eEF3 in Saccharomyces cerevisiae and EttA in Escherichia coli have been found to function as ribosomal translation factors. Several other ABCFs including biochemically characterized VgaA, LsaA and MsrE confer resistance to antibiotics that target the peptidyl transferase center and e...

Within the larger ABC superfamily of ATPases, ABCF family members eEF3 in Saccharomyces cerevisiae and EttA in Escherichia coli have been found to function as ribosomal translation factors. Several other ABCFs including biochemically characterised VgaA, LsaA and MsrE confer resistance to antibiotics that target the peptidyl transferase centre and e...

Electrospinning enables to design and manufacture novel drug delivery systems capable of advancing the local antibacterial therapy. In this study, two hydrophilic drugs - metronidazole and ciprofloxacin hydrochloride - were loaded both individually and in combination into hydrophobic polycaprolactone (PCL) matrix using electrospinning. We aimed to...

Persistence is a reversible and low-frequency phenomenon allowing a subpopulation of a clonal bacterial population to survive antibiotic treatments. Upon removal of the antibiotic, persister cells resume growth and give rise to viable progeny. Type II toxin-antitoxin (TA) systems were assumed to play a key role in the formation of persister cells i...

Antibacterial drug-loaded electrospun nano- and microfibrous dressings are of major interest as novel topical drug delivery systems in wound care. In this study, chloramphenicol (CAM) loaded polycaprolactone (PCL) and PCL/polyethylene oxide (PEO) fiber mats were electrospun and characterized in terms of morphology, drug distribution, physicochemica...

Considerable evidence about phenotypic heterogeneity among bacteria during infection has accumulated during recent years. This heterogeneity has to be considered if the mechanisms of infection and antibiotic action are to be understood, so we need to implement existing and find novel methods to monitor the effects of antibiotics on bacteria at the...

Uropathogenic strains of Escherichia coli (UPEC) are the major cause of bacteremic urinary tract infections. Survival in the bloodstream is associated with different mechanisms that help to resist serum complement-mediated killing. While phenotypic heterogeneity of bacteria has been shown to influence antibiotic tolerance, the possibility that it m...

The survival of bacteria largely depends on signaling systems that coordinate cell responses to environmental cues. Previous studies on the two-component ColRS signal system in Pseudomonas putida revealed a peculiar subpopulation lysis phenotype of colR mutant that grows on solid glucose medium. Here, we aimed to clarify the reasons for the lysis o...

We have recently found that Pseudomonas putida deficient in ColRS two-component system is sensitive to phenol and displays a serious defect on solid glucose medium where subpopulation of bacteria lyses. The latter phenotype is significantly enhanced by the presence of phenol in growth medium. Here, we focused on identification of factors affecting...

Comparative analysis of subpopulations with different DNA content by staining of cells with SYTO9 and PI or SYTO9 alone. P. putida wild-type (wt) and ttgC-deficient (ttgC) strains were grown for 24 h on gluconate minimal plates supplemented with 8 mM phenol. Cells were stained with PI and SYTO9 (SYTO9+PI) or SYTO9 alone and analysed by flow cytomet...

Plate assay of phenol tolerance of P. putida PaW85 (wt) and colR-deficient (colR) strains. Cells were grown on glucose (glc) minimal medium in the presence or absence of 8 mM phenol. Approximate number of inoculated bacterial cells is indicated above the figure. Bacteria were photographed after 4 days of growth.

Description of subpopulation "Dead". P. putida wild-type (A, C, E) and colR-deficient (B, D, F) strains were grown for 24 h on glucose minimal plates supplemented with 3 mM phenol. Cells were stained with SYTO9 alone (A, B) or with SYTO9 and PI (C-F) and analysed by flow cytometry. Fluorescence at 530 (30) is plotted against fluorescence at 616 (23...

ColRS two-component system is well conserved in pseudomonads, but its exact role has remained obscure. Here, we report that Pseudomonas putida deficient in ColR experiences serious carbon source-specific stress that leads to the lysis of a subpopulation of bacteria growing on solid glucose medium. We observed that on glucose medium colR-deficient b...

Transcription of the plasmid-borne phenol catabolic operon pheBA in Pseudomonas putida is activated by the LysR-family regulator CatR in the presence of the effector molecule cis,cis-muconate (CCM), which is an intermediate of the phenol degradation pathway. In addition to the positive control of the operon, several factors negatively affect transc...

As reported, the two-component system ColRS is involved in two completely different processes. It facilitates the root colonization ability of Pseudomonas fluorescens and is necessary for the Tn4652 transposition-dependent accumulation of phenol-utilizing mutants in Pseudomonas putida. To determine the role of the ColRS system in P. putida, we sear...

Käesolev doktoriväitekiri keskendub erinevatele signaalidele, mida tajub mullabakter Pseudomonas putida kokkupuutes aromaatse süsinikuühendiga fenool. P. putida on võimeline kasutama fenooli ainsa süsiniku- ja energiaallikana plasmiidse pheBA operoni ja kromosomaalse katehholi lagundamist võimaldava raja koosavaldumisel. Töö esimeseks eesmärgiks ol...