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BACKGROUND: To date only scanty data exist regarding the effect of failed debridement, antibiotics, irrigation and retention of the prostheses (DAIR) and negative pressure wound therapy (NPWT) on the outcome of a subsequent exchange arthroplasty. OBJECTIVE: The objective of this study was to determine the success rate of a two- or multi-stage procedure after initial failed DAIR/NPWT in patients with an acute periprosthetic joint infection (PJI) and to evaluate the influence of possible risk factors for treatment failure. METHODS: Nineteen consecutive patients with a persisting PJI and ongoing NPWT after treatment of an acute PJI with DAIR of the hip or knee joint from October 2010 to June 2017 were included. All patients were treated according to a structured treatment algorithm after referral to our hospital. The endpoint was a successful reimplantation with absence of signs of infection two years after replantation (“replantation group”) or treatment failure (“treatment failure group”) in terms of a permanent girdlestone arthroplasty, fistula, amputation or death. A risk factor analysis was performed between the two groups. RESULTS: Explantation was performed in 15 cases, amputation in one case, and DAIR/establishment of a fistula in three cases. The treatment success rate after reimplantation in terms of “definitively free of infection” two years after surgery according to Laffer was 36.85% (seven out of 19 patients). Statistical analysis revealed the number of surgeries until wound consolidation (p= 0.007), number of detected bacterial strains (p= 0.041), a polymicrobial PJI (p= 0.041) and detection of a difficult-to-treat organism (p= 0.005) as factors associated with treatment failure. After failed DAIR/NPWT we could detect a significant higher number of different bacterial strains (p= 0.001). CONCLUSIONS: The treatment success rate after failed DAIR and NPWT with 36% is low and associated with a high treatment failure rate (permanent girdlestone arthroplasty, fistula or amputation, death). Thus, the definition of risk factors is crucial. We found that the number of revisions until wound consolidation, a polymicrobial PJI and detection of a difficult-to-treat organisms were risk factors for treatment failure. Furthermore, after failed DAIR/NPWT we could detect a significant higher number of different bacterial strains, with a possible adverse effect on a consecutive exchange.

Infection is one of the most challenging complications after total joint arthroplasties affecting up to 30,000 patients in the US per year. This study investigates the psycho-social burden induced by the two-stage intervention in infected hip or knee replacements. All patients were treated with a two-stage exchange and were assessed at three different timepoints regarding their psychological conditions. Our findings suggest that psychological sequelae after treatment of periprosthetic joint infection are clearly underestimated in the literature and psychological correlates and side effects should be further highlighted during the training process of young surgeons.

Hintergrund Rezidivierende mukokutane Infektionen durch PVL-positive Staphylococcus (S.) aureus-Stamme stellen in Deutschland ein zunehmendes Problem dar. In den letzten Jahren wurden Ausbruche in Kindertagesstatten und Kommunen beschrieben. Dennoch liegen zurzeit keine diagnostischen Algorithmen oder Therapieempfehlungen fur die entsprechenden Infektionen in Deutschland vor. Methode Eine Literaturrecherche in der Datenbank PubMed/MEDLINE erfolgte mit dem Ziel, einen diagnostischen und therapeutischen Algorithmus zu erarbeiten. Zudem wurden nationale und internationale Empfehlungen berucksichtigt. Ergebnisse Panton-Valentine Leukozidin (PVL) ist ein porenbildendes Protein, das von bestimmten S. aureus-Stammen produziert wird. Sowohl Methicillin-sensible (MSSA) als auch Methicillin-resistente S. aureus (MRSA)-Stamme konnen das fur die PVL-Produktion verantwortliche Gen lukS-lukF besitzen. Das klinische Bild der durch einen PVL-positiven S. aureus verursachten Infektionen erstreckt sich von einzelnen rezidivierenden Abszessen bis hin zu einer ausgedehnten Furunkulose. Bei etwa 40 % der Patienten kommt es zu Rezidiven der Beschwerden trotz einer konsequenten Behandlung der Erstinfektion. Die Therapie variiert je nach klinischem Bild der jeweiligen Infektion. Zudem wird in der Literatur eine Screeninguntersuchung der Patienten und ihrer engen Kontaktpersonen sowie eine bakterielle Dekolonisation der Betroffenen empfohlen. Schlussfolgerungen Diese Arbeit fokussiert auf die Pathogenese und Risikofaktoren der rezidivierenden mukokutanen Infektionen durch PVL-positive S. aureus-Stamme und versucht einen diagnostischen und therapeutischen Algorithmus zur optimalen Patientenversorgung vorzuschlagen.

Der Einfluss der Unfallkinematik auf die Verletzungen der Halswirbelsaule (HWS) findet in den gangigen Klassifikationssystemen neben dem Kraftvektor aktuell keine Berucksichtigung. Inwieweit die Unfallstarke einen zusatzlichen Einfluss auf Zahl und Komplexitat der Verletzungen hat und ob sich dies klassifizieren lasst, ist noch nicht abschliesend untersucht. Inwieweit hat neben der Kraftrichtung auch die Kraftstarke Einfluss auf Verletzungen der HWS? Anhand der AOSpine-Klassifikationen fur die obere und subaxiale HWS erfolgte eine retrospektive Fallauswertung von 134 Traumapatienten. Analog der S3-Polytrauma-Leitlinie erfolgten eine Zuordnung in 6 Unfallgruppen und die Einteilung der Verletzungsmorphologie anhand der CT-Schnittbildgebung. Eine hohere Unfallenergie hat einen signifikanten Einfluss auf die Anzahl an Verletzungen (p = 0,005). Bei Niedrigrasanzunfallen ist C2 der am haufigsten verletzte Wirbelkorper (WK) (51 %; p = 0,022), bei Hochrasanzunfallen C7 (37 %; p = 0,017). Auserdem lies sich zeigen, dass die obere HWS bei steigendem Alter und niedriger Unfallenergie vermehrt bei weiblichen (z. B. Sturz aus dem Stand) und die untere HWS bei Hochrasanzunfallen bei jungeren mannlichen Patienten verletzt ist (p = 0,012). Eine genaue Kenntnis des Unfallmechanismus ist bei der Traumaversorgung hilfreich. Verletzungsmuster konnen besser abgeschatzt und die angemessene Diagnostik eingeleitet werden. Die Ergebnisse unterstreichen erneut die Wichtigkeit einer konsequenten HWS-Immobilisation auch bei Bagatelltraumata. Bei Hochrasanzunfallen ist die untere HWS haufiger verletzt, insbesondere C7. Aufgrund der Haufung mehrsegmentaler Verletzungen ist die radiologische Abklarung der gesamten WS nach Hochrasanztrauma zu empfehlen.

The role and diagnostic value of the synovial complement system in patients with low-grade periprosthetic joint infection (PJI) are unclear. We sought to evaluate, for the first time, the usefulness of synovial complement factors in these patients by measuring the individual synovial fluid levels of complement factors (C1q, C3b/iC3b, C4b, C5, C5a, C9, factor B, factor D, factor H, factor I, properdin, and mannose-binding lectin [MBL]). The patients (n = 74) were classified into septic (n = 28) and aseptic (n = 46). Receiver-operator characteristic curves and a multiple regression model to determine the feasibility of a combination of the tested cytokines to determine the infection status were calculated. The synovial fluid levels of C1q, C3b/C3i, C4b, C5, C5a, MBL, and properdin were significantly elevated in the PJI group. The best sensitivity and specificity was found for C1q. The multiple regression models revealed that the combination of C1q, C3b/C3i, C4b, C5, C5a, and MBL was associated with the best sensitivity (83.3%) and specificity (79.2%) for a cutoff value of 0.62 (likelihood ratio: 4.0, area under the curve: 0.853). Nevertheless, only a combined model showed acceptable results. The expression patterns of the complement factors suggested that PJI activates all three pathways of the complement system.

Background: Failed reconstruction in cases of severe acetabular bone loss, with or without pelvic discontinuity, in revision total hip arthroplasty (rTHA) remains a great challenge in orthopaedic surgery. The aim of this study was to describe the outcome of a “second” rTHA with “custom-made acetabular components (CMACs)” after a previously failed reconstruction with CMACs. Methods: 4 patients with severe acetabular bone loss (Paprosky Type IIIB), who required a second rTHA after a previously failed reconstruction with CMAC, due to prosthetic joint infection (PJI), were included in our retrospective study. All prostheses had been constructed on the basis of thin-layer computed-tomography scans of the pelvis. The second rTHA was considered unsuccessful in the event of PJI or aseptic loosening (AL) with need for renewed CMAC explantation. Results: The treatment success rate after second rTHA with a CMAC was 50% (2 of 4). In the successful cases, the visual analogue scale (VAS) score and Harris Hip Score (HHS) after the second rTHA (VAS range 2–4; HHS range 45–58 points) did not differ from those after the first rTHA, before onset of symptoms (VAS: range 2–4; HHS: range 47–55 points). In the failed cases, the second CMACs needed to be explanted due to PJI, with renewed detection of previous pathogens. Patients with treatment failure of the second CMAC had required a higher number of revision surgeries after explantation of the first CMAC than patients with a successful outcome. Conclusions: In patients with severe acetabular bone loss and previously failed rTHA with CMACs, repeat rTHA with a CMAC may be a solid treatment option for patients with an “uncomplicated” multi-stage procedure, i.e., without persisting infection after explantation of the original CMAC. While the outcome in terms of clinical function does not appear negatively affected by such a “second attempt,” the complication rate and risk of reinfection, nonetheless, is high.

Periprosthetic joint infection (PJI) is a feared complication after arthroplasty. Our hypothesis was that PJI caused by difficult-to-treat (DTT) pathogens has a worse outcome compared with non-DTT PJI. Routine clinical data on 77 consecutive patients with confirmed PJI treated with 2-stage exchange arthroplasty were placed in DTT and non-DTT PJI groups and analyzed. The main outcome variable was that the patient was definitively free of infection after 2 years. We found definitive infection resolution in 31 patients in the DTT group (68.9%) and 28 patients (87.5%) in the non-DTT group (P < 0.05). The necessity for revision surgery until assumed resolution of infection was significantly more frequent in the DTT group with 4.72 ± 3.03 operations versus 2.41 ± 3.02 operations in the non-DTT group (P < 0.05). PJI caused by DTT bacteria is associated with significantly higher numbers of revision operations and significantly inferior definitive infection resolution.

Musculoskeletal hydatidosis is a rare but severe disease in central Europe. This case report presents the incidental finding of an osseous hydatidosis after cementless revision total hip arthroplasty in a patient without a preoperative history of hydatidosis or any clinical symptoms. Revision total hip arthroplasty had been necessary due to a septic osteonecrosis of the femoral head 2 years after osteosynthesis of a traumatic proximal femur fracture with a sliding hip screw. The positive sample was taken out of the greater trochanter in the area of the possible former entry point for the lag screw, which was macroscopic inconspicuous. Sero-analysis could afterwards confirm the suspected diagnosis. Postoperative chemotherapy with albendazole was performed for 6 months. A full-body MRI did not reveal any further cysts. This case demonstrates a possible impact of migration on the expected pathogens in revision arthroplasty. This demonstrates that in revision arthroplasty, an infection with this parasite also has to be taken into account, if the patients come from an area endemic for hydatidosis.

Surgical equipment, and especially the so-called ‘splash basins’ that are used intraoperatively, are a potential source of bacterial contamination in primary total hip arthroplasty (THA). With this risk in mind, many commercially available draping kits include plastic bags that can be used to collect fluid or to temporarily store instruments. Following this rationale, we hypothesised that first: the fluid collection bags are a potential reservoir of bacteria and second: there is a time dependency for bacterial contamination. After ethics approval, we investigated in a prospective, internally controlled, non-blinded trial 43 patients who received primary THA. At the beginning of the surgery, we took deep, representative, intracapsular tissue samples, which served as negative controls. At the end of surgery, tissue samples were taken from the bottom of the ‘fluid collection bag’ for microbiological analysis. All 86 control samples were negative. Out of the samples taken from the bags, a pathogen could be detected in four patients (9.3%). All pathogens were detected after a surgery time lasting longer than 90 min. We were able to show that fluid collection bags are a potential reservoir for bacteria in THA when surgery time was greater than a 90-min threshold. Our data suggest that the risks from fluid collection bags outweigh the advantages of using them. Therefore, we recommend against the use of fluid collection bags intraoperatively in primary THA.

Background Prosthetic joint infections (PJI) are a disastrous and feared complication in arthroplasty. Over the past decades, surgeons have tried to lower infection rates through all sorts of improvements. At present, it is impossible to reduce the risk to zero. As the contamination of surgical instruments and the surgical field has been identified as a remaining gap prone for infection, scalpel blades among others have become a focal point of several studies. This study is the first to compare the effect of adhesive incision drapes on contamination rates of scalpel blades in primary arthroplasty of the hip and knee. Methods A total of 344 microbiologic blade culture results from 2 study groups with and without drape usage and 1 group with known PJI were analyzed and compared to histopathologic and microbiologic tissue results. Results In 78% of all positive cultures, the bacteria were part of the local skin flora. The contamination rate for the skin blades with a drape was 3.81% vs 12.19% without drape usage. A significant difference was determined between positive skin blade culture results incision drape usage (P = .031). The different pathogens likely responsible for the PJI correlated with the deep blade cultures (P ≤ .01). The overall contamination rate of surgical blades (1.37%) is comparatively low to the results obtained from other surgical equipment in literature. None of those blade-positive patients developed a surgical site infection during 12-month follow-up. Conclusion Iodine-impregnated incision drapes are able to reduce surgical skin blade contamination. Further studies may be needed to assess the relationship between blade contamination and surgical site infections.

We read with interest the recent review by Tilg et al ,1 which summarised the role of microbiota in liver diseases and pointed out that a causal link with systemic inflammation has still not been established. This letter fills in this gap and provides an analysis of the circulating microbiota in portal vein as the link between gut and liver. The access to portal circulation is possible during the implantation of a transjugular intrahepatic portosystemic shunt (TIPS). Therefore, we characterised the circulating microbiome in portal vein (first venous outflow in gut–liver axis), liver outflow, central venous blood and peripheral venous blood from seven patients with decompensated liver cirrhosis receiving TIPS for either variceal bleeding (n=3) or refractory ascites (n=4) (mean Model for End-stage Liver Disease (MELD) 8.4 (range 6–13), Child-Pugh-Score (CHILD) A: n=4, CHILD B: n=3) (figure 1A). We performed 16S ribosomal RNA (rRNA) gene sequencing of buffy coat samples and identified 65 genera belonging to four phyla (predominantly Proteobacteria) in this cohort (online supplementary figure 1 and figure 1B). Blood microbiome phylum compositions identified in our …

Periprosthetic joint infection is among the most common and severe complications in total joint arthroplasty. Today, a combination of different methods is used for diagnosis because no single method with sufficient sensitivity and specificity is available. In this study, we explored the usability of single-molecule microscopy to characterize synovial fluid samples from periprosthetic joint infections. Patients (n = 27) that needed revision arthroplasty underwent the routine diagnostic procedures for periprosthetic joint infection of the University Hospital in Bonn. Additionally, the diffusion rate of two probes, dextran and hyaluronan, was measured in small volumes of periprosthetic synovial fluid samples using single-molecule microscopy. To evaluate the suitability of single-molecule microscopy to detect PJI the AUC for both markers was calculated. The diffusion rate of hyaluronan in periprosthetic synovial fluid from patients with septic loosening was faster than in samples from patients with aseptic loosening. Single-molecule microscopy showed excellent diagnostic performance, with an area under the receiver operating characteristic curve of 0.93, and allowed the detection of periprosthetic joint infection in patients that would be challenging to diagnose with current methods. For the first time, single-molecule microscopy was used to detect periprosthetic joint infection. Our results are encouraging to study the value of single-molecule microscopy in a larger patient cohort. The speed and accuracy of single-molecule microscopy can be used to further characterize synovial fluid, potentially allowing intraoperative diagnosis of periprosthetic joint infections in the future.

Severe acetabular bone loss, both with or without pelvic discontinuity, remains a challenge in revision total hip arthroplasty (RTHA). The goal of our study was to evaluate the mid-term results for consecutive patients with Paprosky III acetabular bone loss with or without pelvic discontinuity who needed RTHA with custom-made acetabular implants and to compare the results to those of other studies. Sixty-eight (68) patients with severe acetabular bone loss (Paprosky Type IIIa and IIIb), who required RTHA, were included in our study. All prostheses were constructed on the basis of thin-layer computed tomography (CT) scans of the pelvis. The visual analogue scale (VAS), Harrison hip score (HHS), and clinical and radiographic follow-up assessments were used to evaluate the outcome. The average follow-up time was 43 months (range 1–120 months). Implant survival at last follow-up was 75% (51 of 68). Kaplan–Meier survival analysis, with explantation as the endpoint, revealed survival rates of 82.7% (3 years) and 77% (5 years). Patients with revision of the acetabular component only had a significant higher survival rate (p 0.012). Overall revision rate was 36.7%. Reinfection rate was 34.4%. Complications included 15 (22%) periprosthetic joint infections (PJI), 7 dislocations (10.2%), and 2 aseptic loosenings (2.9%). Mean VAS at last follow-up was 1.45 compared to 3.2 preoperatively, while mean HHS improved from 21.1 points preoperatively to 61 at last follow-up. The change in both scores was thus significant (p

Background Recurrent mucocutaneous infections caused by PVL-positive Staphylococcus (S.) aureus strains represent an increasing problem in Germany. Although there have been several outbreaks at day care centers and in urban communities in recent years, there are currently no diagnostic algorithms or treatment recommendations for these particular infections in Germany. Methods We performed a literature search in the PubMed/MEDLINE database with the goal of developing an algorithm for diagnosis and treatment of these infections. National and international recommendations were also considered. Results Panton-Valentine leukocidin (PVL) is a pore-forming protein produced by certain S. aureus strains. Both methicillin-susceptible (MSSA) and methicillin-resistant S. aureus (MRSA) strains may carry the lukS-lukF gene responsible for PVL production. The clinical presentation of infections caused by PVL-positive S. aureus ranges from isolated recurrent abscesses to extensive furunculosis. Despite adequate treatment of primary infections, approximately 40 % of patients develop recurrent disease. The choice of treatment regimen is guided by the clinical presentation of the infection. In addition, some scientific literature recommends bacteriological screening of patients and their contacts, followed by decolonization of affected individuals. Conclusions The present article focuses on the pathogenesis and risk factors of recurrent mucocutaneous infections caused by PVL-positive S. aureus strains and proposes a diagnostic and therapeutic algorithm for optimal patient care.

ZusammenfassungDie Therapie der periprothetischen Osteitis im Rahmen einer Endoprotheseninfektion ist nicht nur ein Determinant der vollständigen Sanierung des Situs, sondern auch ein entscheidender Faktor für die Auswahl und Stabilität des Revisionsimplantats. Nach einer nur eingeschränkt möglichen präoperativen bildmorphologischen Detektion von osteitischen Arealen im periimplantären Gewebe ist die gründliche und vor allem radikale Resektion von avitalen, biofilmtragenden Knochensequestern die Grundlage für eine nachhaltige Keimfreiheit des Prothesenlagers. Des weiteren zählen ein adäquates Totraummanagement, z. B. durch antibiotikatragende Spacer, und die hochkonzentrierte systemische Antibiose zu den Grundpfeilern der Osteitistherapie. Der vorliegende Artikel beschreibt die zugrundeliegende Pathophysiologie, bildgebende Diagnostika im Osteitisnachweis und gibt einen Einblick in die zuvor genannten Therapiegrundsätze.

Streptococcus pneumoniae is one of the major pathogens in invasive diseases in children worldwide. The implementation of national vaccine programs has led to a significant reduction in most circulating pathogenic serotypes. Because of genetic shifts and replacements in the S. pneumoniae population, rare and nonvaccine serotypes have increased in prevalence. We report a case of a 12-month-old girl with Down syndrome and congenital heart disease, suffering from a fulminant pneumococcal meningoencephalitis caused by the nonvaccine serotype 23A. This nonvaccine serotype is an example of the increasing incidence in children with invasive pneumococcal disease (IPD) and illustrates the need for pneumococcal vaccines with broader coverage. Cranial computed tomography (CCT) findings of the patient revealed unusual and extended lesions with bi-hemispheric infarctions and cerebritis, with subsequent widespread intraparenchymal hemorrhage.

Periprosthetic joint infections (PJIs) are a major complication in total joint arthroplasty. Staphylococcus aureus and coagulase-negative staphylococci are known to cause the majority of all PJIs. This study aimed to analyze the eradication rates of S. aureus and S. epidermidis with methicillin susceptibility and methicillin resistance in a 2-stage therapy algorithm. Seventy-four patients with PJI caused by methicillin-resistant S. aureus (MRSA), methicillin-resistant coagulase-negative staphylococci (MRSE), methicillin-susceptible S. aureus (MSSA), and methicillin-susceptible coagulase-negative staphylococci (MSSE) were included, and the outcome was analyzed retrospectively. After a minimal follow-up of 2 years, n = 56 patients (75.7%) were definitively free of infection. The analysis revealed significant differences between the groups, with eradication rates as follows: MSSA (92.6%), MSSE (95.2%), MRSA (80%), and MRSE (54.2%). MRSE showed a significantly lower rate of patients graded as “definitively free of infection” as compared to patients with infections caused by MSSA, MSSE, and MRSA.

Periprosthetic joint infection (PJI) is one of the most challenging complications in orthopedic surgery. In cases of suspected periprosthetic joint infection several diagnostic methods are available. In this study we investigated the performance of the newly available Unyvero i60 implant and tissue infection (ITI) multiplex PCR System. 62 specimens from 31 patients with suspected PJI or aseptic loosening of a painful joint arthoplasty were included in this study. Besides the established diagnostic procedures we included a commercial multiplex PCR detection system for diagnosis of PJI. The PCR results obtained from analysis of sonication and synovial fluids (62 specimens) showed a sensitivity of 66.7%, a specificity of 100%, a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 68.4% when compared to cultural methods. Notably, cultures from sonication fluid displayed a sensitivity of 88.9%, a specificity of 61.5%, a PPV of 76.2% and a NPV of 80.0% when compared to tissue cultures. In conclusion, multiplex PCR is an additional - rapid - method for diagnosing PJI. Positive results with the PCR assay used in this study were always confirmed by subsequent matching culture positivity. However, apart from the time saved the nucleic acid amplification technique did not yield additional information than that obtained from microbiological cultures.

Total joint arthroplasty is a common operation worldwide with infection rates between 1% and 3%. In cases of suspected periprosthetic joint infection, it is very challenging to rule out the causative microorganisms. In this study, we compared the appearance of periprosthetic membranes with the microbiological results obtained from cultures of sonication fluid and the correlation between classical microbiological cultures and cultures of sonication fluid. The results confirmed a strong correlation of bacterial growth in sonication fluid cultures with bacterial growth in classical microbiological cultures. Most importantly, however, our study documented a highly significant correlation of periprosthetic membranes typical for periprosthetic joint infection (PJI) with bacterial growth in sonication fluid. Sonication fluid cultures yielded a better sensitivity than tissue cultures (72.34-60.87%). These 3 methods are useful tools in diagnosing PJIs, and even more, sonication fluid cultures should be included in the diagnostic path of PJI.

Prosthetic joint infections (PJI) are a serious and challenging complication after total joint arthroplasty. According to the literature, most PJI are monomicrobial infections caused by gram-positive cocci. The number of polymicrobial PJI might be underrepresented in the literature and only limited data are available regarding the outcome of polymicrobial PJI. Our hypothesis was that polymicrobial PJI are associated with a reduced cure rate compared with monomicrobial PJI. Routine clinical data were collected and analysed retrospectively as anonymised, aggregated data. A total of 77 consecutive patients with 77 confirmed PJI and proven infectious organism of the hip and knee joint treated within a two-stage exchange concept and a follow-up ≥ two years were investigated. Detection of the infectious organism was based on multiple microbiological cultures taken intra-operatively. Superficial wound swabs or swabs from sinus tracts were not taken into account. Data were grouped into polymicrobial and monomicrobial PJI. The main outcome variable was “definitively free of infection after two years” as published. Second, we considered several variables as potential confounders or as risk factors. A total of 42 men and 35 women with 46 infected total hip arthroplasties and 31 infected total knee arthroplasties were evaluated. In 37 (46.6 %) of our 77 patients a polymicrobial PJI could be detected. We found a significant association between polymicrobial PJI and the outcome parameter definitively free of infection after two years with an odds ratio (OR) of 0.3 [95 % confidence interval (CI) 0.1–1.0]. The rate of patients graded as definitively free of infection after two years was 67.6 % for polymicrobial infections vs. 87.5 % for monomicrobial infections. The American Society of Anesthesiologists (ASA) score (OR 0.4, 95 % CI 0.2–1.0, p = 0.062) was identified as a borderline significant covariable. Our data suggest that polymicrobial PJI might be underrepresented in the current literature. Additionally, the presence of multiple infectious organisms is associated with a reduced rate after two years with 67.6 vs 87.5 % for monomicrobial infections. Special attention and extra care should be considered for these patients.

In orthopedic patients, foreign body-associated infections, especially periprosthetic joint infections (PJIs), are a devastating complication of arthroplasty. Infection requires complex treatment, may result in long hospitalization and causes considerable costs. Multiple surgical revisions can be necessary in these patients, with a loss in function as well as in quality of life. The routine preoperative diagnostics include blood examination for C-reactive protein (CRP) and other biomarkers, as well as joint aspirate analysis for cell count, differentiation, and culture. Intraoperative specimens for histology and microbiology are also standard procedure. The microbiological examination of removed implants with sonication, in combination with the implementation of molecular biology techniques in microbiology, represent two novel techniques currently employed to enhance the differential diagnostics of PJI. We present here the step-wise procedure of analyzing joint aspirate and sonication fluid, using a cartridge-based multiplex polymerase chain reaction (PCR) system. Results were matched against conventional cultures and consensus criteria for PJI. Conventional microbiological cultures from tissue biopsies, joint aspirate and sonication fluid showed a sensitivity of 66.7%, 66.7%, and 88.9%, respectively, and a specificity of 82.3%, 54.6%, and 61.5%, respectively. The PCR diagnostic of the sonication fluid and the joint fluid showed a sensitivity of 50.0% and 55.6%, respectively, and both a specificity of 100.0%. Both PCR diagnostics combined had a sensitivity of 66.7% and a specificity of 100.0%. The multiplex PCR therefore presents a rapid diagnostic tool with moderate sensitivity but high specificity in diagnosing PJI.

The aim of this study was to test the identification of methicillin resistance in coagulase-negative staphylococci by routine matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). SCCmec cassettes of type II, III and VIII encode a small peptide called PSM-mec in the vicinity of mecA. It is visible at m/z 2415 during MALDI-TOF MS of whole cells of Staphylococcus aureus. In view of the fact that psm-mec has been identified in methicillin-resistant coagulase-negative staphylococci, we evaluated a collection of clinical coagulase-negative staphylococci, that contained 77.03% of methicillin-resistant isolates, for the presence of the structural gene encoding PSM-mec and the appearance of the corresponding signal during mass spectroscopy. In MALDI-TOF MS spectra, 89.65% of the strains that harbored the gene yielded the correct signal, corresponding to a sensitivity of 0.897 and a specificity of 1.0. However, regarding detection of methicillin resistance, i. e. considering all resistant strains as positive regardless of the presence of the gene, the overall sensitivity of the test decreased to 0.285, due to the fact that only 29.43% of all resistant isolates contained psm-mec. In conclusion, the presence of the signal in MALDI-TOF MS quickly indicates methicillin-resistance in coagulase-negative staphylococci but its absence does not indicate susceptibility to methicillin.

Antibiotic therapy is essential in foreign body associated infections. The treatment regime should aim at high tissue concentrations, high bioavailability, high biofilm penetration and good tolerance. We investigated whether the new cephalosporin ceftobiprole is active against clinical isolates from musculoskeletal foreign body associated infections. One hundred ninety-six staphylococci isolates (coagulase negative staphylococci and Staphylococcus aureus) derived from foreign body associated infections were tested towards susceptibility to ceftobiprole, using a test strip assay and broth microdilution. The MIC for all strains S. aureus indicated susceptibility to ceftobiprole. The MIC of only two strains of coagulase negative staphylococci was above 2 mg/L. Our results show that ceftobiprole might be considered as an off-label treatment option in foreign body associated infections.

We report a traveler who acquired a Salmonella enterica subspecies enterica serovar Typhi strain with resistance against β-lactams, cephalosporins (extended-spectrum β-lactamase-producing type SHV-12), and quinolones (plasmid-mediated quinolone resistance gene qnrB7). After clinical deterioration using meropenem monotherapy, treatment success was achieved after commencement of fosfomycin in conjunction with high-dose meropenem. The case illustrates clinical challenges of multidrug-resistant S. Typhi.

Acinetobacter baumannii is an emerging nosocomial pathogen primarily in countries with a high prevalence of multidrug resistance. Here we report the detection of a bla OXA23 carbapenemase-producing A. baumannii strain in a German patient with prosthetic hip joint infection following several hip joint surgeries but no history of foreign travel.

Background Periprosthetic joint infections (PJI) are often treated by two stage exchange with the use of an antibiotic impregnated spacer. Most of the two-stage exchange algorithms recommend the implantation of an antibiotic-impregnated spacer during the first stage for a period of 2–24 weeks before reimplantation of the new prosthesis. For the spacer to have a therapeutic effect, the local antibiotic concentration must be greater than the minimal inhibition concentration (MIC) against the pathogens causing the PJI. It must remain so for the entire spacer period, otherwise recurrence of infection or resistances might occur. The question as to whether a sufficient concentration of antibiotics in vivo is reached for the entire spacer period has not been answered satisfactorily. Case presentation We here present a case of a histologically confirmed chronic PJI 20 month after primary arthroplasty. The primary knee arthroplasty was performed due to osteoarthritis of the joint. Initial assessment did not detect a causative pathogen, and two stage exchange with a vancomycin-gentamycin impregnated spacer was performed. At the time of reimplantation, sonication of the explanted spacer revealed a multi-resistant strain of staphylococcus epidermidis on the device and in the joint. Adaption of the therapy and prolonged treatment successfully eradicated the infection. Conclusion According to the authors’ knowledge, the case presented here confirms for the first time the surface contamination (proven through sonication) of a vancomycin-/gentamicin- impregnated Vancogenx®-spacer with a MRSE after ten weeks of implantation. This case study demonstrates the difficulties still associated with the diagnostics of PJI and the published different two stage treatment regimes with the use of antibiotic impregnated spacers.

Pantoea agglomerans is a rare isolate in orthopaedic patients. We describe the first case of an acute hip prosthetic joint infection (PJI) caused by Pantoea agglomerans. The microorganism was detected after sonication of the removed hip endoprosthesis.

BACKGROUND: Fusobacterium nucleatum is a strict anaerobic microorganism that causes disease entities such as periodontal and soft tissue abscesses, pulmonary and intraabdominal infections and very rarely intracerebral infections. CASE PRESENTATION: Here, we report the rare case of a previously healthy 25-year-old German man with a cerebellar abscess caused by Fusobacterium nucleatum that resulted in rapid brain death. Toxicological screening showed positivity for amphetamines and cannabis. The diagnosis was obtained by polymerase chain reaction amplification of bacterial deoxyribonucleic acid in cerebrospinal fluid. CONCLUSIONS: In drug users clinicians should think about rare causes of brain abscesses/meningitis. Early diagnosis is necessary and justifies the use of molecular techniques.