Isabelle Bekeredjian-Ding

A multicentre cohort study on colonization and infection with ESBL-producing Enterobacteriaceae in high-risk patients with haematological malignancies

BACKGROUND Bloodstream infections (BSIs) caused by enterobacteria remain a leading cause of mortality in patients with chemotherapy-induced neutropenia. The rate and type of colonization and infection with ESBL-producing Enterobacteriaceae (ESBL-E) and their mode of transmission in German cancer centres is largely unknown. METHODS We performed a prospective, observational study at five German university-based haematology departments. Participating sites screened for intestinal ESBL-E colonization within 72 h of admission, every 10 ± 2 days thereafter and before discharge. Three of the five centres performed contact isolation for patients colonized or infected with ESBL-E. Molecular characterization of resistance mechanisms and epidemiological typing of isolates by repetitive extragenic palindromic PCR (rep-PCR) and PFGE was performed to assess strain transmission between patients. RESULTS Between October 2011 and December 2012, 719 hospitalizations of 497 haematological high-risk patients comprising 20,143 patient-days were analysed. Mean duration of in-hospital stay was 36.6 days (range: 2-159 days). ESBL-E were identified from screening samples (82.8% Escherichia coli and 14.6% Klebsiella pneumoniae) in 55/497 patients (11.1%; range by centre: 5.8%-23.1%). PFGE and rep-PCR revealed only a single case of potential cross-transmission among two patients colonized with K. pneumoniae. Six episodes of BSI with ESBL-E were observed. Multivariate analysis revealed previous colonization with ESBL-E as the most important risk factor for BSI with ESBL-E (OR 52.00; 95% CI 5.71-473.89). CONCLUSIONS Even though BSI with ESBL-E is still rare in this high-risk population, colonization rates are substantial and vary considerably between centres. In-hospital transmission of ESBL-E as assessed by molecular typing was the exception.

Epidemiology of invasive aspergillosis and azole resistance in patients with acute leukaemia: the SEPIA Study

Invasive aspergillosis (IA) is a serious hazard to high-risk haematological patients. There are increasing reports of azole-resistant Aspergillus spp. This study assessed the epidemiology of IA and azole-resistant Aspergillus spp. in patients with acute leukaemia in Germany. A prospective multicentre cohort study was performed in German haematology/oncology centres. The incidence of probable and proven aspergillosis according to the revised EORTC/MSG criteria was assessed for all patients with acute leukaemia [acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL)]. Cases were documented into a web-based case report form, and centres provided data on standards regarding prophylactic and diagnostic measures. Clinical isolates were screened centrally for azole resistance and, if applicable, underlying resistance mechanisms were analysed. Between September 2011 and December 2013, 179 cases of IA [6 proven (3.4%) and 173 probable (96.6%)] were diagnosed in 3067 patients with acute leukaemia. The incidence of IA was 6.4% among 2440 AML patients and 3.8% among 627 ALL patients. Mortality at Day 84 was 33.8% (49/145) and attributable mortality was 26.9% (39/145). At Day 84, 53 patients (29.6%) showed a complete response, 25 (14.0%) a partial response and 17 (9.5%) a deterioration or failure. A total of 77 clinical Aspergillus fumigatus isolates were collected during the study period. Two episodes of azole-resistant IA (1.1%) were caused by a TR/L98H mutation in the cyp51A gene. With only two cases of IA due to azole-resistant A. fumigatus, a change of antifungal treatment practices in Germany does not appear warranted currently.

False non-susceptible results of tigecycline susceptibility testing against Enterobacteriaceae by an automated system: a multicentre study.

It has been previously shown that different antimicrobial susceptibility testing (AST) methodologies can influence susceptibility results for tigecycline (Hope et al., 2010; Cohen Stuart et al., 2010; Marchaim et al., 2014; Torrico et al., 2010). Even within a single AST method, several testing conditions including medium age and ion content may cause discrepant results (Bradford et al., 2005; FernandezMazarrasa et al., 2009). For tigecycline, Leal Castro et al. (2010) and Lat et al. (2011) provided early data demonstrating overestimation of MICs and resistance rates by Vitek 2 system. Our study, therefore, aimed to systematically determine the error rates of tigecycline AST for Enterobacteriaceae by Vitek 2 (focusing on false non-susceptible results) as well as other automated systems in comparison to a reference method. Additionally, we compared several other AST methods and testing conditions.

Plasmacytoid Dendritic Cells: Neglected Regulators of the Immune Response to Staphylococcus aureus

Plasmacytoid dendritic cells (pDC) are a rare subset of leukocytes equipped with Fcγ and Fcε receptors, which exert contrary effects on sensing of microbial nucleic acids by endosomal Toll-like receptors. In this article, we explain how pDC contribute to the immune response to Staphylococcus aureus. Under normal circumstances the pDC participates in the memory response to the pathogen: pDC activation is initiated by uptake of staphylococcal immune complexes with IgG or IgE. However, protein A-expressing S. aureus strains additionally trigger pDC activation in the absence of immunoglobulin. In this context, staphylococci exploit the pDC to induce antigen-independent differentiation of IL-10 producing plasmablasts, an elegant means to propagate immune evasion. We further discuss the role of type I interferons in infection with S. aureus and the implications of these findings for the development of immune based therapies and vaccination.

Multidrug resistant Acinetobacter baumannii reaches a new frontier: prosthetic hip joint infection

Acinetobacter baumannii is an emerging nosocomial pathogen primarily in countries with a high prevalence of multidrug resistance. Here we report the detection of a blaOXA23 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.

Rapid brain death caused by a cerebellar abscess with Fusobacterium nucleatum in a young man with drug abuse: a case report

BackgroundFusobacterium 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 presentationHere, 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.ConclusionsIn drug users clinicians should think about rare causes of brain abscesses/meningitis. Early diagnosis is necessary and justifies the use of molecular techniques.

Detection of Pantoea agglomerans in hip prosthetic infection by sonication of the removed prosthesis: The first reported case

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.

B cell encounters with apoptotic cells

Autoantibodies directed against nuclear antigens often arise in autoimmune disease associated with the failure to clear apoptotic cells in a swift and timely manner. Nucleic acids present in apoptotic cells and in membranous microparticles derived thereof exert adjuvant activity in the immune response to apoptosis. The scope of this review is to provide an overview on the current knowledge on B cell responses to apoptotic cells and membranous microparticles. Although physiological B cell responses to apoptotic cells result in the release of IL-10 by B cells and immunosuppression, pathological responses lead to autoantibody formation. Toll-like receptors specific for nucleic acids are engaged in both types of responses. In this review we delineate the functional impact of nucleic acids on B cell responses in the context of apoptosis.

In vitro analysis of nucleic acid recognition in B lymphocytes.

In contrast to murine B cells, Toll-like receptor (TLR) expression in human B cells is mainly restricted to endosomally localized TLR7 and -9, receptors for RNA and DNA, respectively. Most importantly, B lymphocytes lack classical phagocytic receptors and instead internalize antigen only via the B cell receptor (BCR), a surface immunoglobulin specific for a defined antigen. BCR ligation triggers internalization of particulate antigens and physically associated molecules among them bacterial DNA or RNA. Thereby, this process provides access to endosomal nucleic acid-sensing TLRs. Co-stimulation of BCR and TLR ultimately leads to T cell-independent B cell activation. Here, we explain how this process can be experimentally mimicked in human peripheral blood B cells, e.g., using a microsphere-based system that promotes uptake of nucleic acid-based TLR ligands via BCR engagement.

Successful management of Candida krusei monoarthritis after allo-SCT.

On day þ 73 after allogeneic PBSC transplantation (alloSCT), a 47-year-old female patient was admitted to our transplantation ward with severe pain in her left knee. Transplantation was performed in October 2012 in the first CR of secondary AML with a complex aberrant karyotype after two induction cycles (ICE protocol). A full-match (10/10) unrelated PBSC graft was transplanted after FLAMSA/ATG conditioning. Immunosuppressive treatment consisted of CsA and mycophenolate mofetil. The patient received posaconazole (3 200 mg/day) as antifungal prophylaxis starting from the day after terminating conditioning. Hematopoietic engraftment was achieved by day þ 19, and on day þ 20 full-donor chimerism was detectable. No significant infectious complications appeared during the hospital stay and the patient was discharged without any signs of acute GVHD on day þ 25. Microbial-surveillance urine testing revealed Candida krusei without any clinical signs of infection. Thus, no specific treatment was initiated and subsequent testings remained negative for fungal and/or bacterial growth. Mycophenolate mofetil was reduced starting on day þ 30 and was removed by day þ 51; CsA taper started on day þ 54 without any signs of acute GVHD due to the high relapse risk constellation. On the day of her admission to our ward, the joint was markedly swollen due to an articular effusion, slightly warmed but not reddened, and no other joints were affected. Owing to elevated laboratory results indicating infection, we immediately initiated antibiotic therapy with meropenem and linezolid while maintaining immunosuppressive CsA taper (actual levels B40 ng/mL) and antifungal prophylaxis. An MRI of the knee on day þ 75 showed articular effusion, synovitis and a big ganglion cyst (Figure 1a). Of note, no pre-existing arthrosis was reported. During the antibiotic therapy, infectious parameters transiently decreased but clinical symptoms persisted. We therefore initiated puncture of the articular effusion on day þ 78, which revealed the growth of C. krusei. Antifungal prophylaxis was immediately switched to antifungal therapy using liposomal amphotericin B (3 mg/kg/day) according to the IDSA (Infectious Diseases Society of America) Guidelines. To date, only limited data are available on the sensitivity of C. krusei to posaconazole. As pharmacokinetic measurements were not evaluated in her daily routine, we further hypothesized that blood levels could have been too low to prevent infection. Nevertheless, in vitro testing of antifungal drug sensitivity in our case revealed sensitivity to posaconazole, supporting the idea of insufficient drug availability. Unfortunately, the volume of synovial fluid was not sufficient to quantify intraarticular drug levels of posaconazole. Owing to an insufficient clinical improvement, we subsequently escalated antifungal treatment to the combination of liposomal amphotericin B and caspofungin, which was also tested to be effective and is recommended as the treatment alternative in the IDSA Guidelines and as the first-line recommendation for invasive candidiasis in the ECIL Guidelines. In this particular case, combination therapy was selected to achieve maximal efficacy and to avoid surgical debridement, which is recommended in the IDSA Guideline and was suggested by the orthopedic surgeons. However, because of the relatively early time point after allo-SCT (day þ 80) with ongoing immunosuppressive medication, surgical intervention was not favored and the combined antifungal treatment was continued. Other manifestations or foci of fungal infection were excluded using whole-body computed tomography scan, transesophageal echocardiography and ophthalmological control. Owing to the rising infection levels, we subsequently switched to a combination therapy of voriconazole together with anidulafungin, as the isolated C. krusei showed very low minimalinhibitory concentrations in vitro and voriconazole might be superior in regard to its diffusion into the articular cavity. Owing to limited improvement of articular pain (especially during walking), we subsequently performed an MRI of the joint on day þ 92, which now showed signs of massive worsening with a more pronounced enrichment of contrast agent due to edema in the tibia. These changes were interpreted as suspected fungal osteomyelitis with concomitant myositis of the popliteal muscle (Figure 1b). Thus, we next decided to perform an arthroscopy to sample effusion as well as synovial and bone tissues to ascertain the diagnosis of C. krusei arthritis with subsequent osteomyelitis before an extensive surgical debridement was performed. The anidulafungin and voriconazole combination antifungal therapy was continued and an antibiotic therapy was initiated on the day of surgery for 10 days. Of note, all specimen (effusion, synovia and bone) were negative for fungal species as detected by culture, PCR and histomorphology (PAS and Grocott staining). In addition, no bacterial infection could be detected. Thus, we interpreted the inflammatory signs seen in the MRI as infection-triggered inflammation (not fulfilling the classical criteria of musculoskeletal or joint GVHD) and subsequently started steroid therapy (1 mg/kg body weight). In parallel, a combination antifungal therapy was continued. This led to a dramatic improvement of clinical symptoms, allowing remobilization of the patient and her discharge on day þ 107 with rapidly decreasing inflammatory signs. Drug levels of voriconazole were adequate (2555 ng/mL) after switching to oral application. Steroids were subsequently tapered and voriconazol subscribed for another 3 months. The patient now is without clinical symptoms and all inflammatory parameters are in the normal range. Only a few cases of conservative treatment of isolated C. krusei monoarthritis in hematological patients are available. To our knowledge, our report is the first one to describe this complication after allo-SCT. Current guidelines recommend antifungal therapy in combination with surgery. We here show that aggressive antifungal therapy can successfully treat fungal infection. Moreover, radiological and clinical signs of worsening may be triggered by an inflammatory response sensitive to steroids. Careful evaluation by extensive sampling from inflamed regions and microbiological testing should precede the use of steroids, as these may aggravate the situation in case of persisting fungal infection. Finally, it remains elusive whether a compliance problem, insufficient drug absorption or limited local penetration of posaconazole into the articular cavity initially allowed fungal growth in the knee of our patient. The case highlights that regular blood level screening might be useful to select patients at risk Bone Marrow Transplantation (2013) 48, 1585–1586 & 2013 Macmillan Publishers Limited All rights reserved 0268-3369/13