CHROMAgar™ LIN-R as an efficient screening tool to assess the prevalence of linezolid-resistant enterococci in German hospital patients-a multicentre study approach, 2021-2022.

BACKGROUND: In recent years, an increasing number of linezolid-resistant enterococci (LRE) was recognized at the German National Reference Centre (NRC) for Enterococci. National guidelines on infection prevention recommend screening for LRE in epidemiologically linked hospital settings without referring to a reliable and rapid diagnostic method. Since 2020, CHROMAgar™ provide a chromogenic linezolid screening agar, LIN-R, suitable to simultaneously screen for linezolid-resistant staphylococci and enterococci. OBJECTIVES: To assess the applicability of CHROMAgar™ LIN-R in clinical settings for detecting LRE directly from patient material and to infer prevalence rates of LRE amongst German hospital patients. METHODS: During the 3-month trial period, clinical samples were plated on CHROMAgar™ LIN-R. Antimicrobial susceptibility testing was performed using VITEK2 or disc diffusion. At the NRC, linezolid resistance was determined by broth microdilution, multiplex-PCR for cfr/optrA/poxtA and by a restriction-based assay for 23S rDNA mutations. RESULTS: The 12 participating study sites used 13 963 CHROMAgar™ LIN-R plates during the study period. Of 442 presumptive LRE, 192 were confirmed by phenotypic methods. Of these, 161 were received by the NRC and 121 (75%) were verified as LRE. Most of LR-E. faecium 53/81 (65%) exhibited a 23S rRNA gene mutation as the sole resistance-mediating mechanism, whereas optrA constituted the dominant resistance trait in LR-E. faecalis [39/40 (98%)]. Prevalence of LRE across sites was estimated as 1% (ranging 0.18%-3.7% between sites). CONCLUSIONS: CHROMAgar™ LIN-R represents a simple and efficient LRE screening tool in hospital settings. A high proportion of false-positive results demands validation of linezolid resistance by a reference method.

Feasibility of Continuous Infusion of Cefiderocol in Conjunction with the Establishment of Therapeutic Drug Monitoring in Patients with Extensively Drug-Resistant Gram-Negative Bacteria.

BACKGROUND AND OBJECTIVE: Resistance to antibacterial substances is a huge and still emerging issue, especially with regard to Gram-negative bacteria and in critically ill patients. We report a study in six patients infected with extensively drug-resistant Gram-negative bacteria in a limited outbreak who were successfully managed with a quasi-continuous infusion of cefiderocol. METHODS: Patients were initially treated with prolonged infusions of cefiderocol over 3 h every 8 h, and the application mode was then switched to a quasi-continuous infusion of 2 g over 8 h, i.e. 6 g in 24 h. Therapeutic drug monitoring (TDM) was established using an in-house liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. RESULTS: Determined trough plasma concentrations were a median of 50.00 mg/L [95% confidence interval (CI) 27.20, 74.60] and steady-state plasma concentrations were a median of 90.96 mg/L [95% CI 37.80, 124]. No significant differences were detected with respect to acute kidney injury/continuous renal replacement therapy. Plasma concentrations determined from different modes of storage were almost equal when frozen or cooled, but markedly reduced when stored at room temperature. CONCLUSIONS: (Quasi) continuous application of cefiderocol 6 g/24 h in conjunction with TDM is a feasible mode of application; the sample for TDM should either be immediately analyzed, cooled, or frozen prior to analysis.

Bacterial Spectrum and Infective Foci in Patients Operated for Infective Endocarditis: Time to Rethink Strategies?

OBJECTIVE: The rising incidence of infective endocarditis (IE) accompanied by the de-escalation of antibiotic prophylaxis and the complexity of surgical treatment makes IE a daunting foe. We reviewed all patients who underwent cardiac surgery for IE at our institution with a focus on causative organisms and infective foci. METHODS: A review of 3,952 consecutive patients who underwent cardiac surgery at our institution between January 2013 and December 2017 revealed 160 patients (4%) who were operated for IE. RESULTS: The predominantly affected valves were the aortic (30%) and mitral valve (26.9%) as well as a combination of both (8.8%). A total of 28.8% of patients suffered from prosthetic valve endocarditis (PVE). The most frequently identified causative organisms were Staphylococcus (45.7%), Streptococcus (27.5%), and Enterococcus species (16.7%), which was predominantly associated with PVE (p = 0.050). In 13.1% of patients, a causative organism has not been detected. The most frequent infective foci were dental (15%), soft-tissue infections (15%), spondylodiscitis (10%), and infected intravascular implants (8.8%). Relevant predisposing factors were immunosuppression (9.4%) and intravenous drug abuse (4.4%). Septic cerebral infarctions were diagnosed in 28.8% of patients. Postoperative mortality was 22.5%. CONCLUSIONS: As the bacterial spectrum and the infective foci are still the "old acquaintances," and with regard to the increasing incidence of IE, current risk-benefit evaluations concerning antibiotic prophylaxis may need to be revisited.

[SARS-CoV-2 antibody response to the second COVID-19 vaccination in neuromuscular disease patients under immune modulating treatment]. / SARS-CoV-2-Antikörper-Antwort auf die zweite COVID-19-Impfung bei neuromuskulären Patienten unter immunmodulierender Therapie.

Successful vaccination (adequate elevation of anti-spike protein antibodies) is attributed with sufficient protection against a severe course of coronavirus disease 2019 (COVID-19). For patients with chronic inflammatory diseases (CID) and immunosuppression the success of vaccination is an ongoing scientific discourse. Therefore, we evaluated the antibody titer against the S1 antigen of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 2 weeks after complete immunization in patients with an underlying neuromuscular disease (NMD), who presented to our neurological day clinic and outpatient department for regular infusions of immunoglobulins. The data show that patients with chronic autoimmune NMD and simultaneous immunosuppressive or immune modulating treatment show an antibody response after vaccination with both mRNA and vector vaccines. In comparison to healthy subjects there is a comparable number of seroconversions due to the vaccination. A correlation between immunoglobulin dose and vaccination response could not be found; however, in contrast, there was a significant reduction of specific antibody synthesis, especially for the combination of mycophenolate mofetil (MMF) and prednisolone.

Blood Culture Headspace Gas Analysis Enables Early Detection of Escherichia coli Bacteremia in an Animal Model of Sepsis.

(1) Background: Automated blood culture headspace analysis for the detection of volatile organic compounds of microbial origin (mVOC) could be a non-invasive method for bedside rapid pathogen identification. We investigated whether analyzing the gaseous headspace of blood culture (BC) bottles through gas chromatography-ion mobility spectrometry (GC-IMS) enables differentiation of infected and non-infected; (2) Methods: BC were gained out of a rabbit model, with sepsis induced by intravenous administration of E. coli (EC group; n = 6) and control group (n = 6) receiving sterile LB medium intravenously. After 10 h, a pair of blood cultures was obtained and incubated for 36 h. The headspace from aerobic and anaerobic BC was sampled every two hours using an autosampler and analyzed using a GC-IMS device. MALDI-TOF MS was performed to confirm or exclude microbial growth in BCs; (3) Results: Signal intensities (SI) of 113 mVOC peak regions were statistically analyzed. In 24 regions, the SI trends differed between the groups and were considered to be useful for differentiation. The principal component analysis showed differentiation between EC and control group after 6 h, with 62.2% of the data variance described by the principal components 1 and 2. Single peak regions, for example peak region P_15, show significant SI differences after 6 h in the anaerobic environment (p < 0.001) and after 8 h in the aerobic environment (p < 0.001); (4) Conclusions: The results are promising and warrant further evaluation in studies with an extended microbial panel and indications concerning its transferability to human samples.

Impact of routine bedside infectious diseases service on clinical management and prognosis of patients with Candida fungemia - an example for Antifungal Stewardship at university level in Germany.

BACKGROUND: Candidemia is rare and has a high mortality rate. This study analyses the impact of bedside antifungal stewardship (AFS) on clinical management and prognosis of patients with candidemia at a university hospital in Germany. METHODS: All patients with at least one positive blood culture with Candida species between 2014 and 2016 received bedside AFS with standardized recommendations. Medical records were retrospectively analyzed. Results from the intervention period from 2014-2016 (n=109), with focus on 2016 (n=39), were compared with those from the pre-intervention period in 2013 (n=30). RESULTS: Bedside AFS was performed in 24/35 (69%) surviving patients in 2016 within the first 3 days after diagnosis of candidemia. All surviving patients (n=35) in 2016 received antifungal treatment compared with 24/28 (86%) in 2013 (p=0.0344). Follow-up blood cultures were performed in 25/35 (71%) in 2016 compared with 10/25 (40%) in 2013 (p=0.0046). Survival in the intervention compared with the pre-intervention group did not differ significantly (p=0.58) one year after the diagnosis of candidemia was made. However, patients with candidemia often have multiple serious comorbidities. CONCLUSIONS: Individualized bedside AFS significantly improves adherence to recommendations for patients with Candida fungemia, especially guideline-oriented diagnostics and therapy. Improving the prognosis of patients with candidemia remains a huge challenge for AFS.

Phenotypic Variability in a Coinfection With Three Independent Candida parapsilosis Lineages.

The human pathogenic yeast Candida parapsilosis has gained significant importance over the past decades as one of the principal causes of fungal bloodstream infections. Isolates of C. parapsilosis are known to be able to switch between several different colony morphologies in vitro, which are correlated with different cell shapes, altered cell surface properties, and thus different capacities to form biofilms on indwelling medical devices. In a set of six clinical specimens from a single surgery patient yielding stable smooth- as well as crepe-morphology isolates, we investigated the differences between five of them on a phenotypic and genomic level. In contrast to the initial assumption that they were switched forms of a clonal strain, karyotyping and genome sequencing showed that the patient was colonized by at least three distinct linages. Statistical analysis placed these groups distantly across the population of C. parapsilosis. Interestingly the single blood culture isolate was of smooth morphology and matched with an isolate from the patient's nose of similar morphology. Strong variation between the isolates was seen in adhesin-encoding genes, where repeat regions showed significant variation in length and repeat-numbers, most strikingly in HWP1 of the smooth isolates. Although no differences in drug susceptibility were evident, the high phylogenetic distance separating the individual strains highlights the need for testing of multiple colonies in routine practice. The absence of biofilm formation in the blood stream isolate indicates a lack of respective adhesins in the cell wall, in turn pointing toward lack of adhesion as a positively contributing factor for dissemination.

Molecular Tools for the Detection and Deduction of Azole Antifungal Drug Resistance Phenotypes in Aspergillus Species.

The incidence of azole resistance in Aspergillus species has increased over the past years, most importantly for Aspergillus fumigatus. This is partially attributable to the global spread of only a few resistance alleles through the environment. Secondary resistance is a significant clinical concern, as invasive aspergillosis with drug-susceptible strains is already difficult to treat, and exclusion of azole-based antifungals from prophylaxis or first-line treatment of invasive aspergillosis in high-risk patients would dramatically limit drug choices, thus increasing mortality rates for immunocompromised patients. Management options for invasive aspergillosis caused by azole-resistant A. fumigatus strains were recently reevaluated by an international expert panel, which concluded that drug resistance testing of cultured isolates is highly indicated when antifungal therapy is intended. In geographical regions with a high environmental prevalence of azole-resistant strains, initial therapy should be guided by such analyses. More environmental and clinical screening studies are therefore needed to generate the local epidemiologic data if such measures are to be implemented on a sound basis. Here we propose a first workflow for evaluating isolates from screening studies, and we compile the MIC values correlating with individual amino acid substitutions in the products of cyp51 genes for interpretation of DNA sequencing data, especially in the absence of cultured isolates.

Environmental isolates of azole-resistant Aspergillus fumigatus in Germany.

Azole antifungal drug resistance in Aspergillus fumigatus is an emerging problem in several parts of the world. Here we investigated the distribution of such strains in soils from Germany. At a general positivity rate of 12%, most prevalently, we found strains with the TR34/L98H and TR46/Y121F/T289A alleles, dispersed along a corridor across northern Germany. Comparison of the distributions of resistance alleles and genotypes between environment and clinical samples suggests the presence of local clinical clusters.