The global increase in antibiotic resistance levels in bacteria is a growing concern to our society and highlights the need for alternative strategies to combat bacterial infections. Bacterial viruses (phages) are the natural predators of bacteria and are as diverse as their hosts, but our understanding of them is limited. The current levels of knowledge regarding the role that phage play in the control of bacterial populations are poor, despite the use of phage therapy as a clinical therapy in Eastern Europe. The aim of this doctoral thesis is to increase knowledge of the diversity and characteristics of bacterial viruses and to assess their potential as therapeutic agents towards multi-resistant bacteria. Paper I is the product of de novo sequencing of newly isolated phages that infect and kill multi-resistant Klebsiella pneumoniae. Based on similarities in gene arrangement, lysis cassette type and conserved RNA polymerase, the creation of a new phage genus within Autographivirinae is proposed. Paper II describes the genomic and proteomic analysis of a phage of the rare C3 morphotype, a Podoviridae phage with an elongated head that uses multi-resistant Escherichia coli as its host. Paper III describes the study of a pre-made phage cocktail against 125 clinical K. pneumoniae isolates. The phage cocktail inhibited the growth of 99 (79 %) of the bacterial isolates tested. This study also demonstrates the need for common methodologies in the scientific community to determine how to assess phages that infect multiple serotypes to avoid false positive results. Paper IV studies the effects of phage predation on bacterial virulence: phages were first allowed to prey on a clinical K. pneumoniae isolate, followed by the isolation of phage-resistant bacteria. The phage resistant bacteria were then assessed for their growth rate, biofilm production in vitro. The virulence of the phage resistant bacteria was then assessed in Galleria mellonella. In the single phage treatments, two out of four phages showed an increased virulence in the in G. mellonella, which was also linked to an increased growth rate of the phage resistant bacteria. In multi-phage treatments however, three out of five phage cocktails decreased the bacterial virulence in G. mellonella compared to an untreated control. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

Multi-resistant bacteria are a growing problem worldwide. In relation to the bacteria spreading, the proportion of patients with multi-resistant bacteria also increase. In nursing, the encounter is described as a central part and works to ensure that the patient can express their feelings. How the meeting takes place has a great impact on whether the patient experiences suffering or not. A professional approach and knowledge regarding patients experience of the encounter as well as communication, forms a basis for the nurse to be able to meet the patient's unique needs in the encounter. The aim of this study is to describe how patients with multi-resistant bacteria experience the encounter with healthcare. This is a literature study is based on analysis of qualitative studies. The ten articles that make up the work have been analysed using a fivestep model. This resulted in two main themes and five sub-themes, which describe the experience of the meeting. The results describe how the staff's hygiene routines, attitudes and knowledge affect how patients experience the encounter. It also highlights the impact of the isolation in which patients are cared for and the stigmatization that was experienced during the encounter. In summary, it showed that patients with multi-resistant bacteria are at risk of experiencing an encounter that is stigmatizing. Patients experienced feelings such as guilt and shame due to the healthcare staff´s routines and attitudes in the meeting.

Bakgrund:  Multiresistenta bakterier (MRB) förekommer i hela världen och klassas  som ett globalt folkhälsoproblem. Kunskapen om multiresistenta bakterier är låg både hos  patienter och sjukvårdspersonal. För att minska risken för spridning behövs mer kunskap och om vikten av följsamhet till basala hygienrutiner. Överdriven användning av antibiotika är en  bidragande orsak till den ökade antibiotikaresistensen i världen.  Sjukvårdspersonal upplever svårigheter med att vårda patienter med MRB och bristande kunskap hos kan ses som bidragande faktor till detta. Att undvika smittspridning är en stor del i hur patienterna ska hanteras inom vården.  Syfte: Att sammanställa patienters upplevelser av att leva med multiresistenta bakterier såsom Meticillinresistenta Staphylococcus aureus (MRSA), Vancomycinresistenta enterokocker (VRE) och Extended Spectrum Beta-Lactamase (ESBL).  Metod: Studien har genomförts som en litteraturöversikt baserat på 15 vetenskapliga artiklar. Artiklarna är av kvalitativ, kvantitativ och mixad ansats. Databaser som använts är CINAHL, PubMed och Scopus.  Resultat: Resultatet presenteras i fyra olika kategorier: Upplevelser av MRB i vardagen, Upplevelser av att få bristande information, Upplevelser av bemötande från sjukvårdspersonal och Upplevelser av stigmatisering. Konklusion: Stigmatisering, oro och ångest genomsyrade resultatet av denna litteraturöversi kt. Sjukvårdspersonalens bemötande spelar en viktig roll i hur patienten hanterar att bli diagnostiserad med multiresistenta bakterier och sen att leva med multiresistenta bakterier.  Okunnig sjukvårdspersonal gav upphov till ökat lidande för patienterna. / Background: Multi-resistant bacteria (MRB) occur worldwide and are classified as a global public health problem. Knowledge of multi-resistant bacteria is low in both patients and healthcare professionals. To reduce the risk of spreading, more knowledge and the importance of adherence to basic hygiene routines are needed. Excessive use of antibiotics is a contributing cause of the increased antibiotic resistance in the world. Healthcare professionals experience difficulties in caring for patients with MRB and lack of knowledge can be seen as a contributing factor. Avoiding the spread of infection is a major part of how patients should be managed in healthcare situations.  Aim: To compile patients' experiences of living with multi-resistant bacteria such as Multiresistant staphylococcus aureus, Vancomycin-resistant enteroccal and Extended-spectrum betalactamase  Method: The study has been conducted as a literature review based on 15 scientific articles.  The articles are of qualitative, quantitative, and mixed method. Databases used in the search  are CINAHL, PubMed and Scopus.  Results: The results are presented in four different categories: Experiences of multi-resistant bacteria in everyday life, Experiences of lack of information, Experiences of treatment from healthcare professionals and Experiences of stigmatization. Conclusion: Stigmatization, anxiety and concern permeated the results of this literature review. The care of healthcare personnel plays an important role in how the patient handles being diagnosed with and then living with multidrug resistant bacteria. Unskilled healthcare  professionals caused increased suffering for patients.

La survenue d’une infection péri prothétique (IPP) est la principale complication de la chirurgie prothétique articulaire, depuis son invention par Robert et Jean Judet en 1947. Comme le nombre de prothèses articulaires posées chaque année augmente de façon importante, ces infections sont de plus en plus fréquentes et l’optimisation de leur prise en charge est un enjeu important sur le plan médical et économique.Les modèles animaux d’IPP permettent de comprendre les mécanismes éthio-pathogéniques et tester de nouvelles thérapeutiques. Une analyse critique de la littérature a été effectuée en évaluant chaque modèle selon son type d’inoculation qui influence les taux et la sévérité de l’infection expérimentale obtenue.Un modèle expérimental d’IPP chez le lapin obtenu par remplacement partiel du genou et inoculation locale a été utilisé pour tester l’efficacité de nouvelles thérapeutiques au cours d’infections à deux bactéries multi résistantes qui posent des problèmes en thérapeutique humaine.Dans un 1er temps nous avons évalué l’efficacité de la ceftaroline (CPT) céphalosporine bactéricide in vivo contre le Staphylococcus aureus résistant à la méticilline (SARM) en la comparant à la vancomycine en association ou non à la rifampicine. 5.107UFC (Unités Formant Colonies) de SARM (Concentration Minimale Inhibitrice (CMI) de 0,38, 0,006, et 1 mg/l pour CPT, RIF, et VAN, respectivement) était injecté dans le genou. Les animaux infectés ont été randomisés et recevaient : aucun traitement (contrôles), CPT (60 mg/kg im), VAN (60 mg/kg im), CPT plus RIF (10 mg/kg im), ou VAN plus RIF débutant 7 jours après l'inoculation et durant 7 jours. L’efficacité des traitements a été évaluée sur la quantité de bactéries persistantes dans l’os (tibia proximal) après traitement. Ce travail a montré que la CPT et la VAN étaient efficace en monothérapie mais que seule l’association avec la rifampicine permettait de stériliser la quasi totalité des animaux. La CPT apparaît donc comme un traitement potentiellement efficace dans cette infection.Dans un 2ème temps nous avons étudié l'efficacité de la colistine (COL) dans le ciment, seule ou en combinaison avec des injections intramusculaires (im) de COL et/ou de méropénème (MRP) dans des infections à Klebsiella pneumoniae résistantes aux carbapénèmes (KPC). Un modèle proche de celui décrit pour le SARM a été utilisé. La souche KPC99YC est une souche clinique, résistante à la gentamicine (CMI 8mg/l) intermédiaire à l'imipénème (CMI 4mg/l), et sensible à la COL (CMI 0,25mg/l). L’inoculum était de 1.109UFC. Sept jours après l'infection, les prothèses étaient remplacées par espaceur sans antibiotique (contrôle), ou par espaceur imprégné de COL (3 MUI de COL/40g de ciment), ou par espaceur sans antibiotique et injections de COL (12 mg/kg im), ou l’association des deux, ou injections de COL avec espaceur en ciment imprégné de COL associé ou non à des injections de MRP (80 mg/kg im). Le traitement durait 7 jours. Tous les lapins témoins étaient infectés à J15, avec une moyenne de densité bactérienne de 6,17 [5,69, 7,04] CFU/g d'os. Contrairement à la COL locale, la COL systémique seule ou combinée avec le MRP était plus efficace que le contrôle sur le nombre de bactéries dans l'os à la fin du traitement. L’association COL locale + systémique était significativement plus efficace que le groupe témoin sur le dénombrement bactérien. D’ailleurs, c'était le seul schéma efficace sur le nombre de lapins avec un os stérile et à la limite de significativité par rapport au traitement systémique seul. Une souche résistante à la COL a été détectée dans le traitement local seul mais pas avec l’association de COL locale et systémique.Les modes d’inoculation directs sont les plus efficaces pour reproduire une IPP aigue. Les études expérimentales permettent de tester des traitements innovants en particulier pour les infections à bactéries multi résistantes. / The occurrence of prosthetic joint infection (PJI) is the main complication of joint prosthetic surgery since its invention by Robert and Jean Judet in 1947. Since the number of articular prostheses placed each year increases significantly, these infections are more and more frequent and the optimization of their management is an important medical and economic stake.The animal models of PJI make it possible to understand the ethiopathogenic mechanisms and to test new therapeutics. A critical analysis of the literature was carried out by evaluating each model according to its type of inoculation which influences the rates and the severity of the experimental infection obtained.An experimental model of PJI in rabbits obtained by partial replacement of the knee and local inoculation was used to test the efficacy of new therapeutics during infections with two multi-resistant bacteria which pose problems in human therapeutics.In a first step we evaluated the efficacy of ceftaroline (CPT) cephalosporin bactericidal in vivo against methicillin-resistant Staphylococcus aureus (MRSA) by comparing it with vancomycin (VAN) in combination with or without rifampin (RIF). 5.107UFC MRSA (Minimum Inhibitory Concentration (MIC) of 0.38, 0.006, and 1 mg/l for CPT, RIF, and VAN, respectively) was injected into the knee. Infected animals were randomized to receive no treatment (control), CPT (60 mg/kg im), VAN (60 mg/kg im), CPT plus RIF (10 mg/kg im) or VAN plus RIF, 7 days after inoculation and for 7 days. The efficacy of treatments was evaluated on the amount of persistent bacteria in the bone (proximal tibia) after treatment. This work has shown that CPT and VAN were effective as monotherapy, but only the combination with RIF allowed the sterilization of almost all animals. CPT appears to be a potentially effective treatment in this infection.In a second step we studied the efficacy of colistin (COL) in cement, alone or in combination with intramuscular (im) injections of COL and/or meropenem (MRP) in carbapenem-resistant Klebsiella pneumoniae infections (KPC). A model close to that used for MRSA was used. The strain KPC99YC is a clinical strain, resistant to gentamicin (MIC 8mg/L) intermediate to imipenem (MIC 4mg/l), and sensitive to COL (MIC 0,25mg/l). The inoculum was 1,109UFC. Seven days after the infection, the prosthesis were replaced by antibiotic-free spacer (control), or by COL-impregnated spacer (3 MIU of COL/40g of cement), or by antibiotic-free spacer and COL injections (12 mg/kg im), or the combination of the two, or COL injections with COL-impregnated cement spacer associated or not with MRP injections (80 mg/kg im). The treatment lasted 7 days. All control rabbits were infected at D15, with median and interquartile range (IQR) bone bacterial count of 6.17 [5.69, 7.04] CFU/g of bones. In contrast to local COL, systemic COL alone or combined with MRP was more effective than control on bacterial counts in bone at the end of treatment. The combination of COL local + systemic was significantly more effective than control group on bacterial counts. Interestingly it was the only effective regimen on the number of rabbits with sterile bone and at the limit of significance vs systemic treatment alone. One COL-resistant strain was detected in the COL local treatment alone but not with the combination of local and systemic COL.Direct inoculation modes are most effective in reproducing an acute PJI. The experimental studies allow testing innovative treatments in particular for the infections with multi-resistant bacteria.