[Bacterial load of the surroundings during rigid diagnostic bronchoscopy under high frequency jet-ventilation]. / Mikrobielle Belastung der Umgebung während der Anwendung der Hochfrequenz-Jetventilation in der Bronchoskopie.

BACKGROUND: High-frequency jet ventilation (HFJV) is used in pneumological endoscopy for rigid, diagnostic, and therapeutic bronchoscopies. It is unclear to what extent the unobstructed flow of respiratory gas from the patient's lungs causes microbial contamination of the surrounding air. MATERIAL AND METHODS: After the start of the HFJV (15 min) in 16 rigid bronchoscopies, airborne pathogen measurements were taken directly at the distal endoscope outlet, at examiner height (40 cm above the endoscope outlet), at a 2 m distance from the endoscope in the room and at the supply air outlet of the examination room using an RCS air sampler. The number and type of pathogens isolated in the air samples were then determined, as well as germs in the bronchoalveolar lavage fluid (BALF) from the patient's lungs. RESULTS: An increased bacterial density (136 and 114 CFU/m3) was detected directly at the distal end of the endoscope and at examiner height at a distance of 40 cm, which decreased significantly with increasing distance from the bronchoscope (98 CFU/m3 at a distance of 2 m and 82 CFU/m3 at the supply air outlet). The most frequently detected bacteria were Staphylococcus spp., Micrococcus spp. and Bacillus spp. In the BALF, pathogens could only be cultivated in four of 16 samples, but the same pathogens were detected in the BALF and the ambient air. CONCLUSION: When performing a rigid bronchoscopy, in which patients are mechanically ventilated in a controlled manner using an open HFJV system, there is an increased pathogen load in the ambient air and therefore a potential risk for the examiner.

Previous antibiotic therapy as independent risk factor for the presence of vancomycin-resistant enterococci in surgical inpatients. Results from a matched case-control study.

BACKGROUND: Investigation of risk factors for the presence of vancomycin-resistant enterococci (VRE) in inpatients on surgical wards and associated intensive care units of a German tertiary care hospital. METHODS: A single-centre retrospective matched case-control study was performed with surgical inpatients admitted between July 2013 and December 2016. Patients with in-hospital detection of VRE later than 48 h after admission were included and comprised 116 VRE-positive cases and 116 VRE-negative matched controls. VRE isolates of cases were typed by multi-locus sequence typing. RESULTS: ST117 was identified as the dominant VRE sequence type. Next to length of stay in hospital or on an intensive care unit and previous dialysis the case-control study revealed previous antibiotic therapy as a risk factor for the in-hospital detection of VRE. The antibiotics piperacillin/tazobactam, meropenem, and vancomycin were associated with the highest risks. After taking into account length of stay in hospital as possible confounder other potential contact-related risk factors such as previous sonography, radiology, central venous catheter, and endoscopy were not significant. CONCLUSIONS: Previous dialysis and previous antibiotic therapy were identified as independent risk factors for the presence of VRE in surgical inpatients.

[Rhinocerebral Mucormycosis]. / Rhinocerebrale Mucormykose.

Mucormycosis is a rare but serious type of fungal infection, which can progress rapidly especially in immunsupressed patients.We report about a 47 year old female patient with ptosis on the left eye. The ophthalmological report offered no further pathologic findings. Diabetes mellitus was known and the blood sugar value was very high.A computed tomography of the paranasal sinuses showed a shadow in the ethmoid bone and in an additonally performed MRI-scan, an increase of orbital fat and an extension of the ocular muscle were visible.As the patient lost her ability o look above, an operation of the paranasal sinus was done.The microbial results revealed a Mucormycosis (Lichtheimia). As the patient went blind in the further course, indication for orbital exenteration on the left side and revision of the paranasal sinus was given. High doses of Liposomal Ampthotericin B and Posaconazol were given and blood sugar was monitored very strictly. MRI-scans revealed a further progression of the infection and required additional surgeries and a dura resection accompanied by complications like recurrent septical episodes, renal insufficiency, a bifrontal epidural hematoma and multiple cerebral microinfarcts that impeded the recovery of our patient in the further course. After 8 months she was able to leave the hospital, an epithesis was adjusted and she is without a relapse for 24 month since the diagnosis.

[New Antibiotics for Treatment of Highly Resistant Gram-negative Bacteria]. / Neue Antibiotika für die Therapie von multiresistenten gramnegativen Bakterien.

New ß-lactam/ß-lactamase inhibitor (BLI) combinations (ceftolozan/tazobactam, ceftazidim/avibactam, meropenem/vaborbactam, imipenem/relebactam, aztreonam/avibactam) are the focus of newly approved antibiotics or those currently in advanced clinical testing. In contrast to the BLI currently available, the new inhibitors avibactam, vaborbactam and relebactam are not structurally ß-lactams.The combination with a BLI protects ß-lactam from degradation by broad-spectrum ß-lactamases from gram-negative pathogens. The main indications for the new substances are therefore infections with multi-resistant gram-negative bacteria.In clinical use, it should be noted that the BLI does not close efficacy gaps in the ß-lactam/BLI combination (e.g. no effect of cephalosporin/BLI combinations on anaerobes or enterococci).Cefiderocol is the first representative of the siderophore cephalosporin antibiotic group to enter phase II clinical testing.Eravacyclin (tetracycline derivative) and plazomicin (aminoglycoside) are new non-ß-lactam antibiotics in advanced clinical testing (phase III).In order to maintain the efficacy of new reserve antibiotics for as long as possible, a prescription should only be made if an additional benefit in comparison to established substances has been proven, e.g. by a resistance test.

Induction of Candida albicans biofilm formation on silver-coated vascular grafts.

OBJECTIVES: Silver exhibits excellent antimicrobial properties and is used to protect medical devices from microbial colonization. Because few data are available on the influence of silver coating of vascular prostheses on Candida biofilm formation, this study aimed to investigate the effect of silver on yeast biofilm formation in an in vitro model. METHODS: Prosthesis material was co-cultivated with two different strains of Candida albicans and the effect of silver on attachment and the growth of biofilms was monitored by microscopy and by quantification of cfu and mitochondrial dehydrogenase activity. RESULTS: Silver collagen-coated vascular prostheses significantly reduced C. albicans biofilm formation in serum-free medium. Paradoxically, in the presence of 50% serum, silver increased the growth of biofilms on silver-containing prostheses 2- to 10-fold compared with silver-free prostheses. Silver ion concentrations between 1.7 and 0.17 mg/L, corresponding roughly to 1/20 to 1/200 of the MIC of silver nitrate, stimulated biofilm formation by C. albicans. CONCLUSIONS: Serum proteins reduced the concentration of silver ions delivered from the surface of vascular prostheses to a subinhibitory level, which stimulated the attachment and biofilm formation of C. albicans on grafts. Silver collagen coating therefore seems to be unsuitable for the prevention of growth of C. albicans on vascular prostheses under physiological conditions.

Taxonomic revision of the African genus Trechosiella Jeannel (Coleoptera: Carabidae: Trechinae).

The genus Trechosiella Jeannel, 1960 (Carabidae: Trechinae) is revised. In addition to the known species T. laetula (Péringuey, 1898), T. scotti (Jeannel, 1937), T. basilewskyi Jeannel, 1960 and T. katicola Jeannel, 1964, T. endroedyyoungai spec. nov., T. oligophthalma spec. nov. and T. scotti swartbergensis subspec. nov. are newly described. Trechosiella laetulaperingueyi (Jeannel, 1926) is recognized as a new synonym of T. laetula sensu stricto. Trechosiella macroptera Casale, 1986 is demoted to become a subspecies of T. scotti, as T scotti macroptera status demotus. An identification key to the known species and subspecies of Trechosiella and a distribution map of the southern African taxa are provided.

Semi-automated contact tracing and management of contact precautions during the COVID-19 pandemic within a tertiary hospital.

Background: Evaluation of a spreadsheet-based COVID-19 contact-tracing tool (CTT) and determination of risk factors for SARS-CoV-2 transmission among hospital staff members. Design: Observational descriptive study on the application and acceptance of the CTT. Retrospective case-control study for SARS-CoV-2 transmission risk factor determination and for evaluation of the CTT's risk stratification algorithm. Setting: Tertiary hospital in Germany. Participants: 3514 contacts of hospital staff members to 322 SARS-CoV-2-positive cases. Methods: A case-control study was performed to identify risk factors for SARS-CoV-2 transmission and for unprotected contacts among staff members. To evaluate strengths and weaknesses of the CTT performance statistics were analyzed and users completed a questionnaire measuring satisfaction and acceptance of the tool. Results: In 2021, the CTT was used for the algorithm-based semi-automated management of 3514 in-hospital contacts. The tool determined the risk category of individual contacts and generated messages for the information of the local public health department, the in-hospital SARS-CoV-2 test center and all staff members who had contact to the index case. Staff members without regular contacts to patients had significantly (P<0.005) more unprotected contacts to other staff members (25.5% vs. 9.6%) and more SARS-CoV-2 transmissions per contact (4.9% vs. 0.6%) than staff members with frequent contacts to patients. The profession "nurse or medical technical service" was associated with significantly (P<0.005) more unprotected contacts between staff members (11.0% vs. 2.6%) compared to the profession "physician". Conclusions: Digital tools can increase the efficiency of in-hospital contact tracing. The CTT enable a timely systematic analysis of risk factors among staff members.

Serratia marcescens outbreak in a neonatal intensive care unit associated with contaminated donor milk.

OBJECTIVE: Investigation of the origin of a Serratia marcescens outbreak in a neonatal intensive care unit. DESIGN: Retrospective case-control study. SETTING: Regional level 3 perinatal center in Germany. PATIENTS: This study included 4 S. marcescens-positive and 19 S. marcescens-negative neonates treated between February 1 and February 26, 2019, in the neonatal intensive care unit. METHODS: A case-control study was performed to identify the source of the outbreak. The molecular investigation of S. marcescens isolates collected during the outbreak was performed using pulsed-field gel electrophoresis and next-generation sequencing. RESULTS: The retrospective case-control study showed a significant correlation (P < .0001) between S. marcensens infection or colonization and consumption of donor milk that had tested negative for pathogenic bacteria from a single breast milk donor. Pulsed-field gel electrophoresis and next-generation sequencing retrospectively confirmed an S. marcescens strain isolated from the breast milk of this donor as the possible origin of the initial outbreak. The outbreak was controlled by the implementation of an infection control bundle including a multidisciplinary infection control team, temporary nutrition of infants with formula only and/or their mother's own milk, repeated screening of all inpatients, strict coat and glove care, process observation, retraining of hand hygiene and continuous monitoring of environmental cleaning procedures. CONCLUSIONS: Low-level contaminated raw donor milk can be a source of infection and colonization of preterm infants with S. marcescens even if it tests negative for bacteria.

Candidiasis caused by Candida kefyr in a neonate: case report.

BACKGROUND: Systemic Candidia infections are of major concern in neonates, especially in those with risk factors such as longer use of broad spectrum antibiotics. Recent studies showed that also term babies with underlying gastrointestinal or urinary tract abnormalities are much more prone to systemic Candida infection. We report a very rare case of candidiasis caused by Candida kefyr in a term neonate. CASE PRESENTATION: Renal agenesis on the left side was diagnosed antenatally and anal atresia postnatally. Moreover, a vesico-ureteral-reflux (VUR) grade V was detected by cystography. The first surgical procedure, creating a protective colostoma, was uneventful. Afterwards our patient developed urosepsis caused by Enterococcus faecalis and was treated with piperacillin. The child improved initially, but deteriorated again. A further urine analysis revealed Candida kefyr in a significant number. As antibiotic resistance data about this non-albicans Candida species are limited, we started liposomal amphotericin B (AMB), but later changed to fluconazole after receiving the antibiogram. Candiduria persisted and abdominal imaging showed a Candida pyelonephritis. Since high grade reflux was prevalent we instilled AMB into the child's bladder as a therapeutic approach. While undergoing surgery (creating a neo-rectum) a recto-vesical fistula could be shown and subsequently was resected. The child recovered completely under systemic fluconazole therapy over 3 months. CONCLUSIONS: Candidiasis is still of major concern in neonates with accompanying risk factors. As clinicians are confronted with an increasing number of non-albicans Candida species, knowledge about these pathogens and their sensitivities is of major importance.

The Need of Antimicrobial Stewardship in Post-Operative Infectious Complications of Abdominal Surgery.

Background: Post-operative infection is a common complication following abdominal surgery. The two most common infections are secondary peritonitis and surgical site infections, which lead to increased perioperative morbidity, prolonged hospitalization, higher mortality rates, and increased treatment costs. In addition to surgical procedures, treatment is based on effective antibiotic therapy. Due to increasing antimicrobial resistance, the correct use of antimicrobials is becoming more complex. Many initiatives call for the implementation of an antimicrobial stewardship (AMS) programme to optimize anti-infective therapy. The review article summarizes current recommendations in anti-infective therapy of post-operative peritonitis and surgical site infections and highlights the importance of an AMS programme in abdominal surgery. Summary: Larger studies evaluating the benefit of AMS in abdominal surgery are lacking. However, national and international guidelines have formulated appropriate recommendations for the rational use of antibiotics in post-operative peritonitis and surgical site infections. The rate of post-operative infections can be significantly reduced by perioperative antibiotic prophylaxis. The increase in multidrug-resistant bacteria complicates anti-infective therapy for post-operative infections. Analysis of local susceptibility patterns helps choose an adequate empiric therapy. A high rate of extended-spectrum beta-lactamase-producing bacteria may necessitate the use of other reserve antibiotics in addition to carbapenems, which are approved for the treatment of complicated intra-abdominal infections. A key role for the AMS team is the subsequent de-escalation of antibiotic therapy which limits the use of unnecessary broad-spectrum antibiotics. Key Messages: The increase in multidrug-resistant bacteria poses challenges for abdominal surgery. Post-operative infections should be treated by an interdisciplinary team of surgeons and specialists for AMS.

[Influence of the COVID-19 pandemic on robotic visceral surgery in Germany]. / Auswirkungen der COVID-19-Pandemie auf die robotische Viszeralchirurgie in Deutschland.

BACKGROUND: Robotic procedures are gaining more and more importance in visceral surgery and seem to develop into an indispensable tool in minimally invasive visceral surgery. In 2020 the COVID-19 pandemic caused unexpected changes in daily surgical routines with still ongoing challenges. We evaluated the impact of the COVID-19 pandemic on robotic visceral procedures and the associated training provided in Germany. MATERIAL AND METHODS: We performed a thorough evaluation of German hospitals and identified 89 surgical departments performing robotic visceral procedures. After extensive topic-related literature search an online questionnaire was developed. It included 35 questions referring to all relevant topics on robotic surgery, such as training programs and influence of the COVID-19 pandemic. The survey was sent via email three times to each department. Descriptive and subgroup analysis were performed. RESULTS: We reported a response to our questionnaire from 22 (24.7%) surgical departments and17 questionnaires were analyzable. The vast majority of them weresurgical departments of university hospitals (58.8%), 17.6% maximum care clinics and 23.5% main care clinics. Robotic procedures were performed for the upper gastrointestinal tract (UGI 88.2%), the hepatopancreaticobiliary system (HPB 82.4%), in the colorectal region (94.1%) and for hernias (35.3%). The relative proportion of robotic operations in comparison to all visceral procedures was between 0.3% and 15.4%. The average conversion rate was 4.6 ± 3.2% referring to 2020. All participating clinics used the robotic DaVinci® system (Intuitive Surgical Inc., CA, USA). In summary 22 robotic systems were used mainly in an interdisciplinary setting (82.4%). For teaching purposes, 7 departments (41.2%) provided a second robotic console. On average 13.2 ± 6.5% of surgeons per clinic were involved in robotic procedures. Defined operating room (OR) teams (82.4%) consisted of consultants, specialists and residents. Team training for surgeons and OR nurses was mainly (52.9%) based on clinic-specific programs. Due to the COVID-19 pandemic the number of robotic procedures decreased in 70.0% of the participating departments compared to 2019 with the highest decline reported during the second quarter of 2020 (64.7%). Referring to this, staff shortage of non-surgical disciplines (anesthesiologists 35.3%, OR nurses 35.3%, intensive care medics 17.6%), COVID-19-specific regulations (58.8%) and limited capacities of intensive and intermediate care (47.1%) were specified as underlying causes. Due to the COVID-19 pandemic, caused by a decline in numbers of robotic procedures, robotic training was paused completely in assistance at the operating table in 23.5% and at the second console in 42.9%. CONCLUSION: Robotic visceral surgery is already implemented with a broad spectrum of operations in many German clinics of different care levels; however, the relative proportion of robotic procedures is low, when compared to the overall caseload of each clinic. Training concepts are heterogeneous and focused on experts. In surgeons with growing experience in robotic surgery, conversion rates are recorded to be very low. There was a negative impact on robotic case numbers and training provided in 2020 caused by the COVID-19 pandemic. Therefore, a further endorsement of robotic training programs and an improvement of training designs seem to be essential tools in order to enforce robotic procedures in visceral surgery.

[Perioperative antimicrobial prophylaxis]. / Perioperative Prophylaxe und Therapie von Infektionen - Perioperative Antibiotikaprophylaxe.

Perioperative antimicrobial prophylaxis (AMP) is an important but not the only procedure to prevent surgical site infections. The effectiveness of AMP to prevent surgical site infections has been proven in numerous studies during the last decades and is part of national and international guidelines. The choice of the antibiotic as well as the duration, time point and mode of application strongly impact on the effectiveness of the prophylaxis. This article provides an overview on recommended antibiotics for AMP and their activity against the expected bacterial pathogens in elective surgery. Furthermore, the current spectrum of microorganisms most frequently isolated from surgical site infections and alternative antibiotic strategies are discussed.

Alternative endogenous protein processing via an autophagy-dependent pathway compensates for Yersinia-mediated inhibition of endosomal major histocompatibility complex class II antigen presentation.

Extracellular Yersinia pseudotuberculosis employs a type III secretion system (T3SS) for translocating virulence factors (Yersinia outer proteins [Yops]) directly into the cytosol of eukaryotic cells. Recently, we used YopE as a carrier molecule for T3SS-dependent secretion and translocation of listeriolysin O (LLO) from Listeria monocytogenes. We demonstrated that translocation of chimeric YopE/LLO into the cytosol of macrophages by Yersinia results in the induction of a codominant antigen-specific CD4 and CD8 T-cell response in orally immunized mice. In this study, we addressed the requirements for processing and major histocompatibility complex (MHC) class II presentation of chimeric YopE proteins translocated into the cytosol of macrophages by the Yersinia T3SS. Our data demonstrate the ability of Yersinia to counteract exogenous MHC class II antigen presentation of secreted hybrid YopE by the action of wild-type YopE and YopH. In the absence of exogenous MHC class II antigen presentation, an alternative pathway was identified for YopE fusion proteins originating in the cytosol. This endogenous antigen-processing pathway was sensitive to inhibitors of phagolysosomal acidification and macroautophagy, but it did not require the function either of the proteasome or of transporters associated with antigen processing. Thus, by an autophagy-dependent mechanism, macrophages are able to compensate for the YopE/YopH-mediated inhibition of the endosomal MHC class II antigen presentation pathway for exogenous antigens. This is the first report demonstrating that autophagy might enable the host to mount an MHC class II-restricted CD4 T-cell response against translocated bacterial virulence factors. We provide critical new insights into the interaction between the mammalian immune system and a human pathogen.

Deciphering the intracellular metabolism of Listeria monocytogenes by mutant screening and modelling.

BACKGROUND: The human pathogen Listeria monocytogenes resides and proliferates within the cytoplasm of epithelial cells. While the virulence factors essentially contributing to this step of the infection cycle are well characterized, the set of listerial genes contributing to intracellular replication remains to be defined on a genome-wide level. RESULTS: A comprehensive library of L. monocytogenes strain EGD knockout mutants was constructed upon insertion-duplication mutagenesis, and 1491 mutants were tested for their phenotypes in rich medium and in a Caco-2 cell culture assay. Following sequencing of the plasmid insertion site, 141 different genes required for invasion of and replication in Caco-2 cells were identified. Ten in-frame deletion mutants were constructed that confirmed the data. The genes with known functions are mainly involved in cellular processes including transport, in the intermediary metabolism of sugars, nucleotides and lipids, and in information pathways such as regulatory functions. No function could be ascribed to 18 genes, and a counterpart of eight genes is missing in the apathogenic species L. innocua. Mice infection studies revealed the in vivo requirement of IspE (Lmo0190) involved in mevalonate synthesis, and of the novel ABC transporter Lmo0135-0137 associated with cysteine transport. Based on the data of this genome-scale screening, an extreme pathway and elementary mode analysis was applied that demonstrates the critical role of glycerol and purine metabolism, of fucose utilization, and of the synthesis of glutathione, aspartate semialdehyde, serine and branched chain amino acids during intracellular replication of L. monocytogenes. CONCLUSION: The combination of a genetic screening and a modelling approach revealed that a series of transporters help L. monocytogenes to overcome a putative lack of nutrients within cells, and that a high metabolic flexibility contributes to the intracellular replication of this pathogen.

Gliotoxin production by clinical and environmental Aspergillus fumigatus strains.

The mycotoxin gliotoxin is produced by fungi of the genus Aspergillus, including the important human pathogen Aspergillus fumigatus. Gliotoxin exerts a broad spectrum of immunosuppressive effects in vitro and is detectable in the sera of patients suffering from invasive aspergillosis. In order to correlate the pathogenic potential of A. fumigatus with the ability to produce gliotoxin and to investigate the taxonomic distribution of gliotoxin-producing Aspergillus strains among clinical isolates, a total of 158 Aspergillus isolates comprising four different species (A. fumigatus, n=100; A. terreus, n=27; A. niger, n=16; A. flavus, n=15) were collected from different medical centers (some originating from probable cases of aspergillosis) and from environmental samples in Germany and Austria. Remarkably, gliotoxin was detected in most culture filtrates of A. fumigatus of both clinical (98%) and environmental (96%) origin. The toxin was also detected, with decreasing frequency, in culture filtrates of A. niger (56%), A. terreus (37%), and A. flavus (13%). The highest gliotoxin concentrations were detected in A. fumigatus strains of clinical (max. 21.35 microg/ml, mean 5.75 microg/ml) and environmental (max. 26.25 microg/ml, mean 5.27 microg/ml) origin. Gliotoxin productivity of other Aspergillus species was significantly lower. Culture supernatants of A. fumigatus strains lacking gliotoxin production showed a significantly lower cytotoxicity on macrophage-like cells and T-cells in vitro. In contrast, lack of gliotoxin production in the other Aspergillus species tested had no significant influence on the cytotoxic effect of culture supernatant on these immune cells.

A deterministic model for the processing and presentation of bacteria-derived antigenic peptides.

The amount and the dynamics of antigen supply to the cellular antigen processing and presentation machinery differ largely among diverse microbial antigens and various types of antigen presenting cells. The precise influence, however, of antigen supply on the antigen presentation pattern of cells is not known. Here, we provide a basic deterministic mathematical model of antigen processing and presentation of microbial antigens. The model predicts that different types of antigen presenting cells e.g. cells presenting or cross-presenting exogenous antigens, cells infected with replicating microbes, or cells in which microbial antigen synthesis is blocked after a certain period of time have inherently different antigen presentation patterns which are defined by the kinetics of antigen supply. The reevaluation of existing experimental data [Sijts, A.J., Pamer, E.G., 1997. Enhanced intracellular dissociation of major histocompatibility complex class I-associated peptides: a mechanism for optimizing the spectrum of cell surface-presented cytotoxic T lymphocyte epitopes. J. Exp. Med. 185, 1403-1411] describing the processing and presentation of two antigenic peptides derived from the p60 proteins of the facultatively intracellular bacterium Listeria monocytogenes shows that p60 proteins accumulating intracellularly during bacterial infection of cells play no measurable role as substrate for the cytosolic antigen presentation pathway.

Management of a cluster of Clostridium difficile infections among patients with osteoarticular infections.

BACKGROUND: Here we describe a cluster of hospital-acquired Clostridium difficile infections (CDI) among 26 patients with osteoarticular infections. The aim of the study was to define the source of C. difficile and to evaluate the impact of general infection control measures and antibiotic stewardship on the incidence of CDI. METHODS: Epidemiological analysis included typing of C. difficile strains and analysis of possible patient to patient transmission. Infection control measures comprised strict isolation of CDI patients, additional hand washings, and intensified environmental cleaning with sporicidal disinfection. In addition an antibiotic stewardship program was implemented in order to prevent the use of CDI high risk antimicrobials such as fluoroquinolones, clindamycin, and cephalosporins. RESULTS: The majority of CDI (n = 15) were caused by C. difficile ribotype 027 (RT027). Most RT027 isolates (n = 9) showed high minimal inhibitory concentrations (MIC) for levofloxacin, clindamycin, and remarkably to rifampicin, which were all used for the treatment of osteoarticular infections. Epidemiological analysis, however, revealed no closer genetic relationship among the majority of RT027 isolates. The incidence of CDI was reduced only when a significant reduction in the use of fluoroquinolones (p = 0.006), third generation cephalosporins (p = 0.015), and clindamycin (p = 0.001) was achieved after implementation of an intensified antibiotic stewardship program which included a systematic review of all antibiotic prescriptions. CONCLUSION: The successful reduction of the CDI incidence demonstrates the importance of antibiotic stewardship programs focused on patients treated for osteoarticular infections.

Prophylactic anti-tumor immunity against a murine fibrosarcoma triggered by the Salmonella type III secretion system.

The potential of an attenuated Salmonella enterica serovar Typhimurium strain as a prophylactic anti-tumor vaccine against the murine fibrosarcoma WEHI 164 was evaluated. Tumor cells were transfected with the DNA sequence encoding the MHC class I-restricted peptide p60(217-225) from Listeria monocytogenes. BALB/c mice received a single orogastric immunization with Salmonella that translocates a chimeric p60 protein via its type III secretion system. Mice were subsequently challenged subcutaneously with p60(217-225)-expressing WEHI cells. In vivo protection studies revealed that 80% of these mice remained free of the fibrosarcoma after challenge, whereas all animals of the non-vaccinated control group did develop tumor growth. In further experiments, the distribution of tetramer-positive p60(217-225)-specific effector and memory CD8 T cells after Salmonella-based immunization and tumor application was analyzed. Costaining with CD62L and CD127 revealed a predominance of p60-specific central memory and effector memory CD8 T cells in spleens, whereas in blood samples the majority of p60-specific lymphocytes belonged to effector and effector memory CD8 T cell subsets. This is the first report demonstrating that a bacterial type III secretion system can be used for heterologous antigen delivery to induce cytotoxic effector and memory CD8 T cell responses resulting in an efficient prevention of tumor growth.

Identification of a cross-reactive HLA-DRB1*0301-restricted CD4 T cell response directed against cholesterol-binding cytolysins from two different pathogens.

Cholesterol-binding cytolysins constitute an evolutionarily conserved family of pore-forming proteins expressed by different gram-positive pathogens. Listeriolysin O, one well-characterized member of the cytolysin family, is also known to induce specific CD4 and CD8 T cell responses upon infection of mice with Listeria monocytogenes. Here we describe an HLA-DRB1*0301-restricted listeriolysin O-derived T cell epitope that is conserved among several members of the cytolysin family. An HLA-DRB1*0301-restricted CD4+ T cell line, established from spleen lymphocytes of L. monocytogenes-infected HLA-DRB1*0301-transgenic mice, cross-reacted with a homologous peptide from perfringolysin O, a cytolysin expressed by Clostridium perfringens. Ex vivo analysis of infected mice revealed an even broader cross-reaction of T cells with homologous peptides derived from perfringolysin O, streptolysin O, and cereolysin O. Interestingly, a cross-reactive memory CD4+ T cell response against the homologous peptides derived from listeriolysin O and perfringolysin O could also be detected in the blood from healthy HLA-DRB1*0301+ human donors. Remarkably, this response was even present in donors who did not exhibit a memory T cell reactivity against a second, non-conserved HLA-DRB1*0301-restricted LLO-derived CD4 T cell epitope, suggesting that cytolysin-producing bacteria other than L. monocytogenes can stimulate a cross-reactive cytolysin-specific immunity.