Microbiological and scanning electron microscopic evaluation of epidural catheters

Abstract

BackgroundEpidural catheters are frequently colonized by gram-positive bacteria. Although the incidence of associated epidural infections is low, their consequences can be devastating. We investigated bacterial growth on epidural catheters by quantitative bacterial culture and scanning electron microscopy (SEM) in order to explore the patterns of epidural catheter colonization.Methods28 patients undergoing major abdominal surgery with thoracic epidurals (treatment ≥72 hours) were studied. Before the removal of the catheter, the skin surrounding the insertion site was swabbed. The entire catheter was divided into extracorporeal, subcutaneous, and tip segments. Skin swabs and catheter segments were quantitatively cultured, bacterial species were identified, and SEM was performed on four selected catheters.Results27 of 28 catheters were included. The percentages of positive cultures were: skin swab 29.6%, extracorporeal segments 11.1%, subcutaneous segments 14.8%, and tip segments 33.3%. One patient was diagnosed with a catheter-associated infection. Staphylococcus epidermidis was cultured from the skin and the catheter extracorporeal, subcutaneous, and tip segments. SEM of this catheter showed bacteria-like and intraluminal host cell-like structures. SEM of two other catheters showed intraluminal fibrin networks in their tip segments.ConclusionsWe present the first SEM pictures of an epidural catheter with a bacterial infection. Bacterial growth developed from the skin to the tip of this catheter, indicating the skin as a primary source of infection. By SEM, catheters with low levels of bacterial growth demonstrated an intraluminal fibrous network which possibly plays a role in catheter obstruction.

Scanning Electron Microscope Examination as an Alternative to Classical Microbiology in the Diagnostics of Catheter-Related Sepsis?

“…Additionally, the formation of a fibrin network in the lumen of the catheter with a low level of bacterial colonisation was confirmed. The network negatively affected the patency of the catheter [ 14 ].…”

Ultrasonografische Früherkennung von Venenveränderungen sowie der Nachweis von Biofilmen auf Venenverweilkathetern beim Pferd

“…Manifeste auf dem Katheter etablierte Biofilme lassen sich in der Kultivierung zumeist nicht nachweisen 22 , 25 , 46 . Hierzu ist die REM die sensiblere Methode, eine Spezifizierung der Bakterien kann dabei allerdings nicht stattfinden 22 , 23 , 25 , 46 , 47 , 48 . Eine nachträgliche Kontamination der REM-Proben kann durch die Negativkontrollen nahezu ausgeschlossen werden.…”

“…Die Funde von körpereigenen Zellen und das meist dichte Fibrinnetz auf der Katheteroberfläche bestätigen, dass der Katheter auch bei einer Nutzungsdauer ab 24 Stunden einer Reaktion mit körpereigenen Zellen unterliegt. Dies konnte kürzlich auch in der Humanmedizin selbst an Epiduralkathetern nachgewiesen werden 23 . So lassen sich auch die zum Teil in Studien ultrasonografisch darstellbaren Pseudokatheter erklären, bei denen bereits vermutet wurde, dass es sich um Fibrinscheiden um den ursprünglichen Katheter oder sogar Endothelneubildungen handelt 43 , 49 .…”

“…Aus der Humanmedizin ist jedoch bekannt, dass sich Bakterien in herkömmlichen Anzuchtverfahren nicht immer nachweisen lassen. Dies betrifft vor allem Biofilme, welche unter anderem bereits auf Implantaten zur Osteosynthese und Zentralvenösen- sowie Blasenkathetern nachgewiesen wurden [22] [23]. Biofilme stellen Bakterienkolonien dar, die an verschiedenen Oberflächen anhaften und eine extrazelluläre Matrix bilden [22].…”

Epidural infections, bacteriostatic drug effects and technical strategies for prevention

“…Catheterization of the epidural space is routinely used in anesthesia and analgesia, which connects the epidural space with the outside environment, through which bacteria can gain access to the epidural space. [1][2][3] Here, the use of epidural filter serves as a physical barrier to prevent ingress of bacteria through the infusion line. In this study, we investigated the survivability of seven typical pathogens in bupivacaine and ropivacaine when contaminated during manipulation (eg, local anesthesia (LA) bolus application/infusion) and the ability of an epidural flat filter to prevent microbial transmission by a contaminated infusion solution until physical occlusion of the filter.…”