Hospital strain colonization by Staphylococcus epidermidis

The skin and mucous membranes of healthy subjects are colonized by strains of Staphylococcus epidermidis showing a high diversity of genomic DNA polymorphisms. Prolonged hospitalization and the use of invasive procedures promote changes in the microbiota with subsequent colonization by hospital strains. We report here a patient with prolonged hospitalization due to chronic pancreatitis who was treated with multiple antibiotics, invasive procedures and abdominal surgery. We studied the dynamics of skin colonization by S. epidermidis leading to the development of catheter-related infections and compared the genotypic profile of clinical and microbiota strains by pulsed field gel electrophoresis. During hospitalization, the normal S. epidermidis skin microbiota exhibiting a polymorphic genomic DNA profile was replaced with a hospital-acquired biofilm-producer S. epidermidis strain that subsequently caused repetitive catheter-related infections.29429

Staphylococcal response to daptomycin in implant-associated infections

The use of medical devices carries the risk of infection. Due to the development of multi-resistant bacteria, missing microcirculation, and biofilm embedded bacteria these implant-associated infections are difficult to treat. For their successful treatment, drugs should act independently of the bacterial physiological state, penetrate the biofilm, and prevent further bacterial adherence to surfaces and formation of bacterial biofilm. Daptomycin (DAP) exhibits concentration-dependent bactericidal activity against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Its target is the bacterial membrane in which it forms pores resulting in membrane depolarization and subsequent cell death. Calcium ions (Ca2+) are indispensable for its activity. DAP does not need cell division or active metabolism for bactericidal activity and is able to penetrate biofilms. Therefore, in this thesis we followed the question whether DAP is efficient in eradicating planktonic and adherent MRSA in an implant-associated infection. In the first part, DAP was bactericidal against stationary grown planktonic MRSA in vitro. Because the physiology of biofilm embedded bacteria is similar to stationary grown planktonic bacteria, DAP alone or in combination with rifampin was applied to treat MRSA in a foreign-body infection model in guinea pigs. DAP in combination with rifampin showed the highest efficacy against planktonic and adherent MRSA compared to rifampin-containing combinations with vancomycin, linezolid and levofloxacin. Additionally, in this combination DAP prevented the emergence of rifampin resistance. However, DAP alone was inefficient against attached and biofilm embedded MRSA in implant-associated infections. Therefore, in the second part of this thesis various factors, which could explain treatment failure, were investigated by evaluating the effect of cell wall components, biofilm, adherence and Ca2+ in vitro and in vivo upon DAP activity. We found that the physiological state of the bacteria had an impact on the efficacy of DAP because DAP was only effective as prophylaxis, i.e. before bacterial adherence. Furthermore, DAP was not able to kill adherent staphylococci in vitro, independently of biofilm, nucleases, adhesins, autolysins, and alanyl-lipoteichoic acids. Resistance of adherent staphylococci was not due to mutations of adherent bacteria, since staphylococci became DAP-susceptible after detachment. Increasing DAP or Ca2+ concentrations partially enhanced killing of adherent staphylococci in vitro and in a murine tissue cage infection model. In summary, DAP alone is not active in an implant-associated infection. This might be due to bacterial adhesion, which is associated with a change of their physiological state. We demonstrated in an implant-associated infection that DAP treatment is improved with Ca2+ and only successful with 2 repeated doses of DAP before and after infection or in combination with rifampin

Phenotypic and Genotypic Methods for detection of Biofilm producing Coagulase Negative Staphylococci in a Tertiary Care Hospital.

INTRODUCTION : Gram positive bacteria are one of the most common isolates in the clinical microbiology laboratory. They are widespread in nature and can be recovered from the environment or as commensal inhabitants of the skin, mucous membranes and other body sites mostly in human and animals. The ubiquity of these gram positive bacteria in nature makes the interpretation of their recovery from patients specimens occasionally difficult unless clinical manifestations of an infectious disease process are apparent. Recovery of these organisms from specimens should always be correlated with the clinical condition of the patient before their role in an infectious process can be established. The present study was undertaken to detect the prevalence of biofilm producing and nonproducing CoNS which were isolated from various clinical materials in our laboratory by three different phenotypic methods such as Congo red agar (CRA) method, Tube method (TM), Tissue culture plate (TCP) method, PCR for detection of the ica gene and to find out the reliable method from above which can be recommended for routine detection of biofilm production in CoNS. AIMS AND OBJECTIVES : 1. To find out the prevalence of CoNS in various clinical samples collected from Govt. Rajaji Hospital (GRH), Madurai. 2. To isolate and characterise the CoNS among the clinical samples. 3. To identify the biofilm producing strains of CoNS in clinical isolates by various phenotypic methods. 4. The antimicrobial susceptibility pattern among the biofilm producing and non biofilm producing CoNS isolates. 5. To compare the various phenotypic methods in the identification of biofilm producing CoNS with PCR and to find out the most sensitive and economic method which is close to PCR that can be recommended for routine screening of Biofilm production in Microbiological laboratories. MATERIALS AND METHODS : The present study was conducted in Government Rajaji Hospital, Madurai, attached to Madurai Medical College. The study period was from June 2011 to May 2012. Ethical committee clearance from the institution was obtained before starting the study and informed written consent was received from the patients before collecting the specimens. A total of 456 clinical samples were collected from the patients admitted in various wards at Government Rajaji Hospital, Madurai. Pus, wound swab samples (from infected bone & joint prosthetic implants, surgical site infections), indwelling catheter samples, blood samples, urine samples were collected from 456 patients admitted at Govt. Rajaji Hospital during the study period. Inclusion Criteria: 1. All age groups and both sexes were included. 2. Patients admitted to various wards (ICU, CCU, IRCU, Orthopeadic, plastic surgery, medicine) with signs and symptom suggestive of impending infections such as infected implants, surgical site infection, urinary tract infection, septicemia, pyrexia of unknown origin were included in this study. RESULTS : Samples of pus, wound swab, blood and urine collected from 456 cases admitted at Govt. Rajaji Hospital, Madurai were included in this study. This study included both sexes of all age group. Out of 456 samples, 165 from wound swab, 103 from pus, 96 from blood and 92 from urine. Among the 456 samples, 424 showed growth and 32 samples showed no growth. Among the 424 isolates, 252 Gram positive cocci (GPC) in groups were Staphylococci species and 172 were Gram negative bacilli (GNB). CONCLUSION : Coagulase negative Staphylococci are responsible for nosocomial infections at GRH, Madurai and Staphylococcus epidermidis is the most commonly isolated CoNS species. • Resistance among CoNS are increasing especially among the patients with the indwelling medical devices due to Biofilm production. • As infection caused by Biofilm producing bacteria are difficult to treat, early diagnosis and management is necessary to reduce morbidity and mortality. • This study was focused on finding out of a simple, economic and more accessible method with high sensitivity and specificity to identify Biofilm production. • Various phenotypic methods were compared with PCR and found that Tissue culture plate method showed high sensitivity and specificity and it is closer to PCR

a retro- and prospective study on „Klinikum im Friedrichshain, Berlin“ 2010 - 2015

Aim of the study was to investigate the outcome on periprosthetic joint infections of hipand knee-arthroplasties and the influence of the treatment in the analysed patient population. Overall, 104 patients with infection of 61 hip and 43 knee arthroplasties treated between 2010 to 2015 in the orthopaedic department of the „Klinikum im Friedrichshain“ (Berlin) were analysed. Patient charts were reviewed retrospectively. A prospective follow-up survey on the further therapeutic process and the functional outcome by means of the WOMAC Score was performed. Data was evaluated by a univariate statistical analysis and the Kaplan-Meier survival method was used to estimate the probability of infectionfree survival of different subgroups. In 91% (95 patients) a two-staged exchange with 12-week implant-free interval combined with dual-antibiotics was performed. An antibiotic loaded bone-cement spacer has been used continuously in infected knee-arthroplasties. 23 cases of infected hip arthroplaties were treated with and 31 cases without spacer. The mean follow-up period was 25.1 months. The mean age was 74 years. Pathogenesis was presumed to be chronic in 65% (68 patients). The mean period between last aseptic surgical procedure and onset of symptoms was 65,9 months. Mainly coagulase-negative staphylococci (38%) and Staphylococcus aureus (15%) were identified in the analysed samples. Compared to the results of intraoperative collected tissue, preoperatively performed joint aspirations yielded in 32% of cases contradictory microbiological findings and preoperative biopsies in 39% of cases. In 12% of cases no reimplantation was performed; in 6% patients deceased before end of therapy. In 79% of performed reimplantation surgeries, no signs of infection occurred until last follow-up. Regarding outcome, no difference between knee and hip arthroplasties was found, but in hip arthroplasties the use of an antibiotic-loaded spacer was linked to a diminished revision-rate, though this effect did not reach statistical significance. Biofilm-active antibiotics (27 patients) showed no improved outcome compared to other antibiotics (63 patients). In acute postoperative infections (12 patients), a higher rate of necessary surgical revisions (50%) than in acute hematogenous (15 patients; revision rate 13%) or chronic infections (59 patients; revision rate 17%) was found. At time of follow-up, 76% of respondents took either no or non-opioid analgesics only. In summary, the therapy of periprosthetic joint infections is highly complex and accompanied by an unsatisfactory high recurrence rate. The use of an antibiotic-loaded spacer seems to be preferable. The role of biofilm-active antibiotics and their impact on the treatment outcome must be further investigated.Ziel der Studie ist es, den Therapieerfolg bei periprothetischen Infektionen von Hüft- und Knie-Totalendoprothesen im untersuchten Patientengut zu erheben und die beeinflussende Faktoren zu identifizieren. Von 2010 bis 2015 wurden in der Klinik für Orthopädie des Klinikums im Friedrichshain (Berlin) 104 Patienten mit einer Infektion von 61 Hüft- und 43 Kniegelenkstotalendoprothesen therapiert und in die retrospektive Studie eingeschlossen. Die entsprechenden Patientenakten wurden bezüglich Anamnese, klinischer Befunde sowie erfolgter operativer und antibiotischer Therapie ausgewertet. Zusätzlich erfolgte prospektiv eine schriftliche Nachbefragung über den weiteren Krankheitsverlauf sowie das funktionelle Ergebnis mittels des WOMAC Scores. Eine univariate statistische Auswertung sowie die Berechnung der Überlebenswahrscheinlichkeit der unterschiedlichen Patientengruppen mittels KaplanMeier-Schätzer wurde durchgeführt. Ein zweizeitiger Wechsel mit 12-wöchigen endoprothesenfreiem Intervall und dualer Antibiotikatherapie wurde in der Mehrheit der Fälle (95 Patienten) durchgeführt. Im Kniegelenk wurde stets ein Knochenzement-Platzhalter eingebracht. Bei infiziertem Hüftgelenk wurde teilweise mit (23 Patienten) und teilweise ohne Platzhalter (31 Patienten) therapiert. Die durchschnittliche Nachbeobachtungszeit betrug 25,1 Monate. Durchschnittlich waren die Patienten 74 Jahre alt. Die Mehrzahl der Infekte (65%;68 Patienten) wurde als chronisch gewertet mit einer durchschnittlichen Dauer von 65,9 Monaten zwischen letztem aseptischen Eingriff und Beginn der Symptome der Infektion. In den untersuchten Proben wurden hauptsächlich koagulasenegative Staphylokokken (38%) bzw. Staphylococcus aureus (15%) isoliert. Präoperativ durchgeführte Punktionen erbrachten in 32% der Fälle widersprüchliche mikrobiologische Befunde im Vergleich zu den intraoperativen Probenentnahmen; präoperative Biopsien in 39% der Fälle. In 12% der Fälle erfolgte keine Reimplantation. 6% der Patienten verstarb vor Beendigung der Therapie. In 79% der erfolgten Reimplantationen waren im Anschluss keine erneuten Anzeichen einer Infektion aufgetreten. Diesbezüglich zeigte sich kein Unterschied zwischen Knie- oder Hüfttotalendoprothesen. Die Nutzung eines temporären Platzhalters (Spacers) war mit einer verbesserten Kontrolle der Infektion verbunden, jedoch erreichte dieser Effekt keine statistische Signifikanz. Patienten, welche mit biofilmaktiven Antibiotika therapiert wurden, erfuhren keinen signifikant besseren Therapieverlauf. In der Patientengruppe mit einer akut postoperativen Infektion (12 Patienten) zeigte sich nach erfolgter Reimplantation eine größere Rate an notwendigen operativen Revisionen (50%) als in der Gruppe mit einer akut hämatogenen (15 Patienten; Revisionsrate 13%) oder chronischen Infektion (59 Patienten; Revisionsrate 17%). Zum Zeitpunkt der Nachbefragung nahmen 76% der Patienten keine oder Nicht-Opioid Analgetika ein. 5 Die Therapie einer periprothetischen Infektion des Hüft- und Kniegelenks ist hochkomplex und derzeit mit einer hohen Rate von Rezidiven einhergehend, welche nicht zufriedenstellend erscheint. Die Verwendung eines antibiotikabeladenen Knochenzementspacer scheint zu bevorzugen zu sein. Die Rolle biofilmaktiver Antibiotika und deren Einfluss auf den Behandlungserfolg muss weiter erforscht werden

Studies on the biosynthesis of myxobacterial natural products

The myxovalargins are natural products from myxobacteria discovered in the course of activity-guided screening in the mid 1980´s, and rediscovered due to anti-biofilm activity. A cooperation project including the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), the HZI Braunschweig, the OCI Hannover and Sanofi Aventis funded by the Bundesministerium für Bildung und Forschung (BMBF) was issued to investigate this promising compound class in terms of bioactivity, biosynthesis and structural diversity. This thesis therefore includes the structure elucidation of derivatives including a revision of the myxovalargin A stereochemistry and improvment of production, derivatization and biosynthesis elucidation of the myxovalargins. In depth studies of the myxovalargin biosynthesis and genetic manipulation were enabled with focus on achieving a supply for further activity testing, generating and isolating a variety of natural and semisynthetic myxovalargins and developing tools to make derivatization possible according to future needs. Exploring the myxovalargin-producing myxobacteria led to the identification of additional interesting biosynthesis clusters, which were investigated for their highlights in biosynthesis. Thereby, the phenyl pyruvate dehydrogenase complex was further investigated on its role in the myxobacterial compounds ripostatin, phenalamide and the hyafurone/ hyapyrone/ hyapyrrolidone compound classes.Die Myxovalargine sind Naturstoffe aus Myxobakterien und wurden im Zuge eines Aktivitätsscrennings Mitte der 80er Jahre identifiziert und schließlich aufgrund ihrer Wirksamkeit gegen Biofilme neu entdeckt. Ein Kooperationsprojekt zwischen dem Helmholtz Institut für Pharmazeutische Forschung im Saarland (HIPS), dem HZI Braunschweig, dem OCI Hannover und Sanofi Aventis gefördert vom Bundesministerium für Bildung und Forschung (BMBF) wurde aufgesetzt, um die vielversprechende Naturstoffklasse im Bezug auf ihre Bioaktivität, Biosynthese und Strukturvarianten zu untersuchen. Diese Doktorarbeit befasst sich mit der Strukturaufklärung der Derivate, einer Revision der Stereochemie des Myxovalargin A und der Verbesserung der Produktion, der Derivatisierung und der Aufklärung der Biosynthese des Myxovalargins. Vertiefende Untersuchungen der Biosynthese und die genetische Manipulation wurden untersucht, um die Durchführung von Bioaktivitätstests zu ermöglichen und die Produktion und Isolierung natürlicher und semisynthetischer Myxovalargine zu erreichen sowie Tools zu entwickeln, um eine Derivatisierung für zukünftige Verwendungszwecke zu ermöglichen. Im Zuge der Untersuchung von Myxovalargin-Produzenten wurden weitere interessante Biosynthesecluster identifiziert. Hiervon wurde der Phenylpyruvat-Dehydrogenase Komplex auf seine Rolle in der Biosynthese der Myxobakteriellen Klassen der Ripostatine, Phenalamide und der Hyafurone/ Hyapyrone/ Hyapyrrolidone untersucht

Evaluation du traitement antibiotique des infections de prothèse vasculaire à Staphylococcus aureus : apport d'un modèle murin

Prosthetic vascular graft infection (PVGI) is an emerging disease, mostly due to staphylococci, with limited data regarding efficacy of current antistaphylococcal agents. We aimed to assess the efficacy of different antibiotic regimens. Six different strains of methicillin-susceptible (MSSA) and methicillin-resistant S. aureus (MRSA) were used. We compared results of minimal biofilm inhibitory and eradicating concentrations (MBICs and MBECs) obtained with a Calgary Biofilm Pin lid Device (CBPD) to those yielded by an original Dacron®-related minimal inhibitory and eradicating concentrations measure model. We then used an original murine model of Staphylococcus aureus vascular material infection to evaluate efficacy of different antibiotic regimens. We finally visualized the effect of antibiotics on biofilm by confocal microscopy. We demonstrated that classical measures of MBICs and MBECs with CPBD could overestimate the decrease of antibiotic susceptibility in material related infections and that the nature of the support used to measure biofilm susceptibility might be influent since results yielded by our Dacron®-related minimal eradicating assay were lower than those found on a plastic device. In our in vivo model, we shown that daptomycin was significantly more bactericidal than comparators for some strains of MRSA or MSSA but not for all. For the majority of strains, it was as efficient as comparators. The addition of rifampicin to daptomycin did not enhance daptomycin efficacy in our model. Finally, we highlighted an in vivo differential effect on biofilm depending on the antibiotic used but also on the bacterial strain evaluated. Our models represent an option to better define the best antibiotic options for PVGIs.Les infections de prothèses vasculaires (IPV) sont des maladies particulièrement graves. Malgré une fréquence finalement assez importante, elles demeurent mal connues. Staphylococcus aureus en est l’agent responsable principal. Les données concernant le traitement antibiotique à administrer pour ces infections sont excessivement pauvres. L’objectif de notre travail était donc de comparer l’efficacité de différents protocoles d’antibiothérapie à l’aide de divers modèles expérimentaux d’IPV. Six souches différentes de S. aureus ont été évaluées : 3 sensibles (SAMS) et 3 résistants à la méticilline (SARM). Nous avons comparé les concentrations minimales inhibitrices et éradicatrices (CMIB et CMEB) au sein du biofilm obtenues avec des techniques classiques sur polystyrène à ceux obtenus à l’aide d’un modèle original in vitro sur Dacron® (dCMIB et dCMEB) ®. Nous avons ensuite utilisé un modèle original d’infection de Dacron chez la souris pour comparer l’efficacité de différents protocoles thérapeutiques. Enfin nous avons visualisé l’effet de ces antibiotiques in vivo par microscopie confocale. Nous avons montré que les mesures classiques de CMIB et CMEB obtenues sur polystyrène pouvaient surestimer la baisse d’efficacité des antibiotiques dans le biofilm et que des mesures sur le matériel d’intérêt pouvaient être plus pertinentes. Dans notre modèle in vivo, la daptomycine pouvait être supérieure que les comparateurs pour certaines souches de SARM et de SAMS mais pas pour toutes. Par contre, si l’ajout de rifampicine était bénéfique pour la cloxacilline et la vancomycine, cela n’était pas le cas pour la daptomycine. Enfin, nous avons visualisés des effets totalement différents sur le biofilm selon les antibiotiques utilisés mais également selon les souches testées. Nos modèles ont permis d’obtenir des informations nouvelles concernant l’antibiothérapie des IPV qui, nous l’espérons, permettront d’aider à la prise en charge des patients