Efficacy and safety of an early oral switch in low-risk Staphylococcus aureus bloodstream infection (SABATO): an international, open-label, parallel-group, randomised, controlled, non-inferiority trial

BACKGROUND

Staphylococcus aureus bloodstream infection is treated with at least 14 days of intravenous antimicrobials. We assessed the efficacy and safety of an early switch to oral therapy in patients at low risk for complications related to S aureus bloodstream infection.

METHODS

In this international, open-label, randomised, controlled, non-inferiority trial done in 31 tertiary care hospitals in Germany, France, the Netherlands, and Spain, adult patients with low-risk S aureus bloodstream infection were randomly assigned after 5-7 days of intravenous antimicrobial therapy to oral antimicrobial therapy or to continue intravenous standard therapy. Randomisation was done via a central web-based system, using permuted blocks of varying length, and stratified by study centre. The main exclusion criteria were signs and symptoms of complicated S aureus bloodstream infection, non-removable foreign devices, and severe comorbidity. The composite primary endpoint was the occurrence of any complication related to S aureus bloodstream infection (relapsing S aureus bloodstream infection, deep-seated infection, and mortality attributable to infection) within 90 days, assessed in the intention-to-treat population by clinical assessors who were masked to treatment assignment. Adverse events were assessed in all participants who received at least one dose of study medication (safety population). Due to slow recruitment, the scientific advisory committee decided on Jan 15, 2018, to stop the trial after 215 participants were randomly assigned (planned sample size was 430 participants) and to convert the planned interim analysis into the final analysis. The decision was taken without knowledge of outcome data, at a time when 126 participants were enrolled. The new sample size accommodated a non-inferiority margin of 10%; to claim non-inferiority, the upper bound of the 95% CI for the treatment difference (stratified by centre) had to be below 10 percentage points. The trial is closed to recruitment and is registered with ClinicalTrials.gov (NCT01792804), the German Clinical trials register (DRKS00004741), and EudraCT (2013-000577-77).

FINDINGS

Of 5063 patients with S aureus bloodstream infection assessed for eligibility, 213 were randomly assigned to switch to oral therapy (n=108) or to continue intravenous therapy (n=105). Mean age was 63·5 (SD 17·2) years and 148 (69%) participants were male and 65 (31%) were female. In the oral switch group, 14 (13%) participants met the primary endpoint versus 13 (12%) in the intravenous group, with a treatment difference of 0·7 percentage points (95% CI -7·8 to 9·1; p=0·013). In the oral switch group, 36 (34%) of 107 participants in the safety population had at least one serious adverse event compared with 27 (26%) of 103 participants in the intravenous group (p=0·29).

INTERPRETATION

Oral switch antimicrobial therapy was non-inferior to intravenous standard therapy in participants with low-risk S aureus bloodstream infection. However, it is necessary to carefully assess patients for signs and symptoms of complicated S aureus bloodstream infection at the time of presentation and thereafter before considering early oral switch therapy.

FUNDING

Deutsche Forschungsgemeinschaft.

TRANSLATIONS

For the German, Spanish, French and Dutch translations of the abstract see Supplementary Materials section.

Prevalence of infectious diseases, immunity to vaccine-preventable diseases and chronic medical conditions among Ukrainian refugees in Germany - A cross sectional study from the German Network University Medicine (NUM)

BACKGROUND

Vulnerability to infectious diseases in refugees is dependent on country of origin, flight routes, and conditions. Information on specific medical needs of different groups of refugees is lacking. We assessed the prevalence of infectious diseases, immunity to vaccine-preventable diseases, and chronic medical conditions in children, adolescents, and adult refugees from Ukraine who arrived in Germany in 2022.

METHODS

Using different media, we recruited Ukrainian refugees at 13 sites between 9-12/2022. An antigen test for acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection, serologies for a range of vaccine-preventable diseases, as well as interferon gamma release assays (IGRAs) for tuberculosis (TB), and SARS-CoV-2 were performed. We assessed personal and family history of chronic medical conditions, infectious diseases, vaccination status, and conditions during migration.

RESULTS

Overall, 1793 refugees (1401 adults and 392 children/adolescents) were included. Most participants were females (n = 1307; 72·3%) and from Eastern or Southern Ukraine. TB IGRA was positive in 13% (n = 184) of the adults and in 2% (n = 7) of the children. Serology-based immunological response was insufficient in approximately 21% (360/1793) of the participants for measles, 32% (572/1793) for diphtheria, and 74% (1289/1793) for hepatitis B.

CONCLUSIONS

We show evidence of low serological response to vaccine-preventable infections and increased LTBI prevalence in Ukrainian refugees. These findings should be integrated into guidelines for screening and treatment of infectious diseases in migrants and refugees in Germany and Europe. Furthermore, low immunity for vaccine-preventable diseases in Ukrainians independent of their refugee status, calls for tailor-made communication efforts.

Prevention of legionella infections from toilet flushing cisterns

INTRODUCTION

Immunocompromised patients are at an increased risk of severe legionella infections. We present the results of an outbreak investigation initiated following a fatal case of hospital-acquired legionellosis linked to contaminated water from a toilet-flushing cistern. Additionally, we provide experimental data on the growth of Legionella spp. in flushing cisterns and propose a straightforward protocol for prevention.

METHODS

We monitored the growth of Legionella spp. in the building's hot- and cold-water systems using quantitative bacterial culture on selective agar. Molecular typing of Legionella pneumophila isolates from the infected patient and the water system was conducted through core-genome multi-locus sequence typing (cgMLST).

RESULTS

Legionella contamination in the hospital building's cold-water system was significantly higher than in the hot-water system and significantly higher in toilet flushing cistern's water compared with cold water from bathroom sinks and showers. Isolates from the patient and from the flushing cistern of the patient's bathroom were identical by cgMLST. In an experimental setting, daily toilet flushing for a period of 21 days resulted in a 67% reduction in the growth of Legionella spp. in the water of toilet flushing cisterns. Moreover, a one-time disinfection of cisterns with peracetic acid, followed by daily flushing, decreased legionella growth to less than 1% over a period of at least seven weeks in these setting.

CONCLUSIONS

One-time disinfection of highly contaminated cisterns with peracetic acid and daily toilet flushing as short-term measure can significantly reduce legionella contamination in flushing cisterns. These measures may aid in preventing legionella infection among immunocompromised patients.

Development of prevalence and incidence of non-tuberculous mycobacteria in German laboratories from 2016 to 2020

Numbers of non-tuberculous mycobacteria (NTM) pulmonary diseases (PD) have been repeatedly reported as increasing over the last decades, particularly in Europe. Sound epidemiological data are however missing for most European regions. This study calculated prevalence and incidence of NTM recovered from patients' lungs in Germany, the largest Central European country, over a five-year period. It furthermore determined regional particularities of NTM species and results from susceptibility testing. 22 German NTM laboratories provided their mycobacteriological diagnostic data of 11,430 NTM isolates recovered from 5998 pulmonary patients representing 30% of all notified NTM-PD cases of Germany from 2016 to 2020. NTM incidence and prevalence were calculated for every study year. The presented epidemiological indicators are particularly reliant as TB surveillance data were used as a reference and TB notification reaches almost 100% in Germany. Laboratory incidence and prevalence of NTM recovered from respiratory samples ranged from 4.5-4.9 and from 5.3-5.8/100,000 for the population of Germany, respectively, and did not change over the five-year study period. Prevalence and incidence were stable also when stratifying for facultative pathogenic NTM, M. avium/intracellulare complex (MAIC), and M. abscessus/chelonae complex (MABSC). The proportion of NTM with drug susceptibility testing (DST) increased from 27.3% (2016) to 43.8% (2020). The unchanging laboratory NTM prevalence/incidence in Germany represents a "ceiling" of possible NTM-PD notification when diagnostic strategies do not change in the coming years. A notable increase in NTM-DST may indicate better notification of NTM-PD and/or awareness of new clinical guidelines but still remains below clinical needs.

Twice weekly polymerase chain reaction (PCR) surveillance swabs are not as effective as daily antigen testing for containment of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) outbreaks: A modeling study based on real world data from a child and adolescent psychiatry clinic

OBJECTIVE

In the coronavirus disease 2019 (COVID-19) pandemic, child and adolescent psychiatry wards face the risk of severe acute respiratory coronavirus 2 (SARS-CoV-2) introduction and spread within the facility. In this setting, mask and vaccine mandates are hard to enforce, especially for younger children. Surveillance testing may detect infection early and enable mitigation measures to prevent viral spread. We conducted a modeling study to determine the optimal method and frequency of surveillance testing and to analyze the effect of weekly team meetings on transmission dynamics.

DESIGN AND SETTING

Simulation with an agent-based model reflecting ward structure, work processes, and contact networks from a real-world child and adolescent psychiatry clinic with 4 wards, 40 patients, and 72 healthcare workers.

METHODS

We simulated the spread of 2 SARS-CoV-2 variants over 60 days under surveillance testing with polymerase chain reaction (PCR) tests and rapid antigen tests in different scenarios. We measured the size, peak, and the duration of an outbreak. We compared medians and percentage of spillover events to other wards from 1,000 simulations for each setting.

RESULTS

The outbreak size, peak, and duration were dependent on test frequency, test type, SARS-CoV-2 variant, and ward connectivity. Under surveillance conditions, joint staff meetings and therapists shared between wards did not significantly change median outbreak size under surveillance conditions. With daily antigen testing, outbreaks were mostly confined to 1 ward and median outbreak sizes were lower than with twice-weekly PCR testing (1 vs 22; P < .001).

CONCLUSION

Modeling can help to understand transmission patterns and guide local infection control measures.

Chimaeribacter arupi a new member of the Yersineacea family has the characteristics of a human pathogen

Chimaeribacter arupi (heterotypic synonym: "Nissabacter archeti") is a facultative anaerobic, newly described Gram-negative rod and belongs to the Yersineacea family. Here, we report the case of a 19-month-old female infant patient who presented to the emergency unit with somnolence and fever. C. arupi was isolated from a positive blood culture, taken via an implanted Broviac catheter, proving a bloodstream infection by the pathogen. The objective of this study was to utilize whole genome sequencing to assess the genes encoding potential virulence associated factors, which may play a role in host tropism, tissue invasion and the subsequent stages in the pathogenesis of a bloodstream infection with C. arupi. The genome of the isolate was completely sequenced employing Illumina MiSeq and Nanopore MinION sequencing and the presumptive virulence associated factors and antimicrobial resistance genes were investigated in more detail. Additionally, we performed metabolic profiling and susceptibility testing by microdilution. The presence of predicted TcfC-like α-Pili suggests that C. arupi is highly adapted to humans as a host. It utilizes flagellar and type IV pili-mediated motility, as well as a number of γ1-pili and a σ-pilus, which may be used to facilitate biofilm formation and adherence to host epithelia. Additionally, long polar fimbriae may aid in tissue invasion. The bacterium possesses antioxidant factors, which may enable temporary survival in phagolysosomes, and a capsule that potentially provides protection from phagocytosis. It may acquire iron ions from erythrocytes through the type 6 secretion system and hemolysins. Furthermore, the isolate exhibits beta-lactamase-mediated penicillin and aminopenicillin resistance. Based on the analysis of the whole genome, we conclude that C. arupi possesses virulence factors associated with tissue invasion and may thus be a potential opportunistic pathogen of bloodstream infections.

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.

Cohort profile: a longitudinal regional cohort study to assess COVID-19 seroprevalence in blood donors - baseline characteristics of the SeMaCo study participants

PURPOSE

The SeMaCo study (Serologische Untersuchungen bei Blutspendern des Großraums Magdeburg auf Antikörper gegen SARS-CoV-2), a prospective, longitudinal cohort study with four survey phases spanning 3-5 months each over a period of 22 months, extends the spectrum of seroepidemiological studies in Germany. We present here a careful characterisation of the initial survey phase of the cohort to provide baseline data on infection incidence and obtained from questionnaires, focussing in particular on the attitude towards COVID-19 vaccinations, the vaccination success and the vaccination acceptance.

PARTICIPANTS

A total of 2195 individual blood donors from the donor pool of the blood donation service of the University Hospital Magdeburg were enrolled in the initial survey phase from 20 January 2021 to 30 April 2021. 2138 participants gave sociodemographic/contact data (51.7% male, mean age 44 years) and 2082 participants answered the vaccination questionnaire.

FINDINGS TO DATE

Out of 2195 participants with antibody results, 1909 (87.0%) were antibody negative. The remaining 286 subjects (13.0%) were either antibody-positive and vaccinated (160/286; 55.9%) or antibody-positive without vaccination information (17/286; 5.9%) or antibody-positive and unvaccinated (109/286; 38.1%). The latter result reflects the rate of true or highly probable SARS-CoV-2 infections in our initial study cohort.

FUTURE PLANS

The study primarily aims to measure the prevalence and long-term kinetics of IgG-antibodies against SARS-CoV-2. Including the baseline, the study foresees four survey periods of 3-4 months each. At each visit, we will assess the blood donors' attitude towards vaccination, the antibody response following vaccination and/or infection, as well as undesired vaccination effects. We aim to test the same participants during the survey periods by repeated invitations for blood donation to ensure a long-term (follow-up) in as many study participants as possible. After the four survey phases, a longitudinal data set will be created that reflects the course of the antibody levels/frequencies as well as the infection and vaccination incidence.

TRIAL REGISTRATION NUMBER

DRKS00023263.

Molecular characterization of Arcobacter butzleri isolates from poultry in rural Ghana

In recent years, Arcobacter butzleri has gained clinical significance as an emerging diarrheagenic pathogen associated with poultry and water reservoirs. The full clinical significance of Arcobacter remains rather speculative due to variable virulence and antibiotic susceptibility of individual strains. The aims of the present study were (i) to identify antibiotic resistance genes (ARGs) in the genome sequences of two multidrug-resistant A. butzleri isolates, (ii) to use multilocus-sequence typing (MLST) to generate a guiding phylogeny of A. butzleri isolates collected in Kumasi, Ghana, (iii) to examine the distribution of ARGs in the test cohort, and (iv) to assess the strain's virulence and possible antibiotic treatment options for arcobacteriosis based on the genome sequences and the ARG distribution. A total of 48 A. butzleri isolates obtained from poultry were included in the analysis. These isolates were genotyped by MLST and the antibiotic susceptibilities of isolates to ampicillin, ciprofloxacin, tetracycline, gentamicin, and erythromycin were tested by disk diffusion. Whole genome sequence data of two multidrug-resistant (MDR) A. butzleri isolates were obtained by a combination of single-molecule real-time (SMRT) and Illumina sequencing technology. A total of 14 ARGs were identified in the two generated genome sequences. For all 48 isolates, the frequency of these 14 ARGs was investigated by PCR or amplicon sequencing. With 44 different sequence types found among 48 isolates, strains were phylogenetically heterogeneous. Four of 48 isolates showed an ARG constellation indicating a multidrug-resistant phenotype. The virulence genes in the two A. butzleri genomes showed that the species might be characterized by a somewhat lower virulence as Campylobacter species. The phenotypic susceptibility data combined with the distribution of the particular ARGs especially oxa-464 and the T81I point mutation of the quinolone resistance determining region (QRDR) in a significant percentage of isolates indicated that macrolides and tetracycline can be recommended for calculated antibiotic treatment of arcobacteriosis in Ghana, but not ampicillin and quinolones.

Molecular epidemiology of enterically colonizing Escherichia coli with resistance against third-generation cephalosporins isolated from stool samples of European soldiers with concomitant diarrhea on deployment in Western African Mali

Extended spectrum beta-lactamases (ESBL) are frequently found in Enterobacterales isolates from Western Africa. However, information on the molecular epidemiology of regional ESBL-positive Enterobacterales strains is scarce. In order to provide epidemiological information, ESBL-positive Escherichia coli isolates from stool samples of European soldiers with diarrhea deployed to a field camp in Mali were subjected to whole-genome sequencing (Illumina MiSeq and Oxford Nanopore MinION) and antimicrobial susceptibility testing. With two exemptions, sequence-based analysis suggested an absence of transmission events between soldiers as indicated by a high genetic diversity of isolates and sequence types, confirming previous rep-PCR results. Third-generation cephalosporin resistance was associated with the presence of bla_CTX-M-15 genes with (n = 14) and without (n = 5) co-occurring bla_TEM-1b genes. Between 0 and 6 virulence and resistance plasmids per isolate were recorded. The detected resistance plasmids could be categorized into five types, which, in turn, share different sequence-identical segments, representing particular antimicrobial resistance gene-associated mobile genetic elements (MGEs). Phenotypic resistance rates within the 19 assessed isolates that showed distinguishable colony morphologies were 94.7% (18/19) against ampicillin-sulbactam and trimethoprim/sulfamethoxazole, 68.4% (13/19) against moxifloxacin, 31.6% (6/19) against ciprofloxacin, 42.1% (8/19) against gentamicin, 31.6% (6/19) against tobramycin, and 21.1% (4/19) against piperacillin-tazobactam and fosfomycin. Virulence-associated genes mediating infectious gastroenteritis were rarely detected. The gene aggR, which is characteristic for enteroaggregative E. coli, was only detected in one single isolate. In summary, we found a variety of different strains and clonal lineages of ESBL-carrying E. coli. Transmission either between soldiers or from common contaminated sources was demonstrated in two cases and played only a minor role in this military field camp, while there were indications that resistance gene bearing MGEs had been exchanged between antimicrobial resistance gene-(ARG-)carrying plasmids.

IL-13 determines specific IgE responses and SARS-CoV-2 immunity after mild COVID-19 and novel mRNA vaccination

After recovery, mild and severe COVID-19 diseases are associated with long-term effects on the host immune system, such as prolonged T-cell activation or accumulation of autoantibodies. In this study, we show that mild SARS-CoV-2 infections, but not SARS-CoV-2 spike mRNA vaccinations, cause durable atopic risk factors such as a systemic Th2- and Th17-type environment as well as activation of B cells responsive of IgE against aeroallergens from house dust mite and mold. At an average of 100 days post mild SARS-CoV-2 infections, anti-mold responses were associated with low IL-13 levels and increased pro-inflammatory IL-6 titers. Acutely severely ill COVID-19 patients instead showed no evidence of atopic reactions. Considering convalescents of mild COVID-19 courses and mRNA-vaccinated individuals together, IL-13 was the predominant significantly upregulated factor, likely shaping SARS-CoV-2 immunity. Application of multiple regression analysis revealed that the IL-13 levels of both groups were determined by the Th17-type cytokines IL-17A and IL-22. Taken together, these results implicate a critical role for IL-13 in the aftermath of SARS-CoV-2 mild infections and mRNA vaccinations, conferring protection against airway directed, atopic side reactions that occur in mildly experienced COVID-19.

Human Erysipelothrix rhusiopathiae infection via bath water – case report and genome announcement

Erysipelothrix rhusiopathiae is a facultative anaerobic, environmentally stable, Gram-positive rod that causes swine and avian erysipelas as a zoonotic pathogen. In humans, the main manifestations described are circumscribed erysipeloid, generalized erysipeloid, and endocarditis. Here, we report a 46-year-old female patient who presented to the physician because of redness and marked functio laesa of the hand, in terms of a pain-related restricted range of motion, and was treated surgically. E. rhusopathiae was detected in tissue biopsy. The source of infection was considered to be a pond in which both swine and, later, her dog bathed. The genome of the isolate was completely sequenced and especially the presumptive virulence associated factors as well as the presumptive antimicrobial resistance genes, in particular a predicted homologue to the multiple sugar metabolism regulator (MsmR), several predicted two-component signal transduction systems, three predicted hemolysins, two predicted neuraminidases, three predicted hyaluronate lyases, the surface protective antigen SpaA, a subset of predicted enzymes that potentially confer resistance to reactive oxygen species (ROS), several predicted phospholipases that could play a role in the escape from phagolysosomes into host cell cytoplasm as well as a predicted vancomycin resistance locus (vex23-vncRS) and three predicted MATE efflux transporters were investigated in more detail.

Impact of neutropenia on clinical manifestations and outcome of Staphylococcus aureus bloodstream infection - A propensity score-based overlap weight analysis in two large, prospectively evaluated cohorts

OBJECTIVE

To investigate whether neutropenia influenced mortality and long-term outcome of Staphylococcus aureus bloodstream infection (SAB).

METHODS

Data from two prospective, multicentre cohort studies (INSTINCT and ISAC) conducted in 20 tertiary care hospitals in 6 countries between 2006 and 2015 were analysed. Neutropenic and severely neutropenic patients (defined by the proxy of total white blood cell count <1000/μl and <500/μl, respectively, at onset of SAB) were compared to a control group using a propensity score model and overlap weights to adjust for baseline characteristics. Overall survival and time to SAB-related late complications (SAB recurrence, infective endocarditis, osteomyelitis, or other deep-seated manifestations) were analysed by Cox regression and competing risk analyses, respectively.

RESULTS

Of 3,187 patients, 102 were neutropenic and 70 were severely neutropenic at onset of SAB. Applying overlap weights yielded two groups of 83 neutropenic and 220 non-neutropenic patients, respectively. Baseline characteristics of these groups were exactly balanced. In the Cox regression analysis, we observed no significant difference in survival between the two groups (death during follow-up: 36.1 % in neutropenic vs. 30.6 % in non-neutropenic patients, hazard ratio 1.21 (95 % CI 0.79-1.83)). This finding remained unchanged when we considered severely neutropenic patients (hazard ratio 1.08 [0.60; 1.94]). Competing risk analysis showed a cause-specific hazard ratio (CSHR) of 0.39 (95 % CI 0.11-1.39) for SAB-related late-complications in neutropenic patients.

CONCLUSIONS

Neutropenia was not associated with a higher survival during follow-up. The lower rate of SAB-related late complications in neutropenic patients should be validated in other cohorts.

Impact of Immunosuppressive Agents on Clinical Manifestations and Outcome of Staphylococcus aureus Bloodstream Infection: A Propensity Score-Matched Analysis in 2 Large, Prospectively Evaluated Cohorts

BACKGROUND

Staphylococcus aureus bloodstream infection (SAB) is a common, life-threatening infection. The impact of immunosuppressive agents on the outcome of patients with SAB is incompletely understood.

METHODS

Data from 2 large prospective, international, multicenter cohort studies (Invasive Staphylococcus aureus Infections Cohort [INSTINCT] and International Staphylococcus aureus Collaboration [ISAC]) between 2006 and 2015 were analyzed. Patients receiving immunosuppressive agents were identified and a 1:1 propensity score-matched analysis was performed to adjust for baseline characteristics of patients. Overall survival and time to SAB-related late complications (SAB relapse, infective endocarditis, osteomyelitis, or other deep-seated manifestations) were analyzed by Cox regression and competing risk analyses, respectively. This approach was then repeated for specific immunosuppressive agents (corticosteroid monotherapy and immunosuppressive agents other than steroids [IMOTS]).

RESULTS

Of 3188 analyzed patients, 309 were receiving immunosuppressive treatment according to our definitions and were matched to 309 nonimmunosuppressed patients. After propensity score matching, baseline characteristics were well balanced. In the Cox regression analysis, we observed no significant difference in survival between the 2 groups (death during follow-up: 105/309 [33.9%] immunosuppressed vs 94/309 [30.4%] nonimmunosuppressed; hazard ratio [HR], 1.20 [95% confidence interval {CI}, .84-1.71]). Competing risk analysis showed a cause-specific HR of 1.81 (95% CI, .85-3.87) for SAB-related late complications in patients receiving immunosuppressive agents. The cause-specific HR was higher in patients taking IMOTS (3.69 [95% CI, 1.41-9.68]).

CONCLUSIONS

Immunosuppressive agents were not associated with an overall higher mortality. The risk for SAB-related late complications in patients receiving specific immunosuppressive agents such as IMOTS warrants further investigations.

Combination therapy with rifampicin or fosfomycin in patients with Staphylococcus aureus bloodstream infection at high risk for complications or relapse: results of a large prospective observational cohort

OBJECTIVES

To investigate whether Staphylococcus aureus bloodstream infection (SAB) patients at high risk for complications or relapse benefit from combination therapy with adjunctive rifampicin or fosfomycin.

METHODS

In this post hoc analysis, SAB patients with native valve infective endocarditis, osteoarticular infections or implanted foreign devices were included. The co-primary endpoints were all-cause 90 day mortality and death or SAB-related late complications within 180 days. To overcome treatment selection bias and account for its time dependence, inverse probability of treatment weights were calculated and included in marginal structural Cox proportional hazard models (MSCMs).

RESULTS

A total of 578 patients were included in the analysis, of which 313 (54%) received combination therapy with either rifampicin (n = 242) or fosfomycin (n = 58). In the multivariable MSCM, combination therapy was associated with a better outcome, that is, a lower rate of death or SAB-related late complications within 180 days (HR 0.65, 95% CI 0.46-0.92). This beneficial effect was primarily seen in patients with implanted foreign devices, in which combination therapy was associated with a lower rate of death or SAB-related late complications within 180 days (HR 0.53, 95% CI 0.35-0.79) and a lower 90 day mortality (HR 0.57, 95% CI 0.36-0.91). Upon agent-specific stratification, we found no significant differences in outcomes between combination therapy containing rifampicin and fosfomycin; however, the number of patients in most subgroups was not large enough to draw firm conclusions.

CONCLUSIONS

In patients with implanted foreign devices, combination therapy was associated with a better long-term outcome. Larger prospective studies are needed to validate these findings.

Metabolic Interdependency of Th2 Cell-Mediated Type 2 Immunity and the Tumor Microenvironment

The function of T cells is critically dependent on their ability to generate metabolic building blocks to fulfil energy demands for proliferation and consecutive differentiation into various T helper (Th) cells. Th cells then have to adapt their metabolism to specific microenvironments within different organs during physiological and pathological immune responses. In this context, Th2 cells mediate immunity to parasites and are involved in the pathogenesis of allergic diseases including asthma, while CD8+ T cells and Th1 cells mediate immunity to viruses and tumors. Importantly, recent studies have investigated the metabolism of Th2 cells in more detail, while others have studied the influence of Th2 cell-mediated type 2 immunity on the tumor microenvironment (TME) and on tumor progression. We here review recent findings on the metabolism of Th2 cells and discuss how Th2 cells contribute to antitumor immunity. Combining the evidence from both types of studies, we provide here for the first time a perspective on how the energy metabolism of Th2 cells and the TME interact. Finally, we elaborate how a more detailed understanding of the unique metabolic interdependency between Th2 cells and the TME could reveal novel avenues for the development of immunotherapies in treating cancer.

A combined oro-nasopharyngeal swab is more sensitive than mouthwash in detecting SARS-CoV-2 by a high-throughput PCR assay

Objectives

The optimal diagnostic specimen to detect SARS-CoV-2 by PCR in the upper respiratory tract is unclear. Mouthwash fluid has been reported as an alternative to nasopharyngeal and oropharyngeal swabs. We compared mouthwash fluid with a combined oro-nasopharyngeal swab regarding test performance.

Methods

In a large refugee facility, we retested individuals with a previous positive test for SARS-CoV-2 and their quarantined close contacts. All individuals were asymptomatic at the time of testing. First, a mouthwash (gargling for at least 5 s) with sterile water was performed. Then, with a single flocked swab the back of the throat and subsequently the nasopharynx were sampled. Samples were inactivated and analysed on a Roche cobas 6800^® system with the Roche SARS-CoV-2 test.

Results

Of 76 individuals, 39 (51%) tested positive for SARS-CoV-2 by oro-nasopharyngeal swab. Mouthwash detected 13 of 76 (17%) infections, but did not detect any additional infection. Samples that were positive in both tests, had lower cycle threshold (Ct)-values for oro-nasopharyngeal samples, indicating a higher virus concentration, compared to samples only positive in oro-nasopharyngeal swabs.

Conclusion

Mouthwash is not as sensitive as combined oro-nasopharyngeal swab in detecting upper respiratory tract infection.

Clinical and microbiological characterization of sepsis and evaluation of sepsis scores

Background

Despite the necessity of early recognition for an optimal outcome, sepsis often remains unrecognized. Available tools for early recognition are rarely evaluated in low- and middle-income countries. In this study, we analyzed the spectrum, treatment and outcome of sepsis at an Ethiopian tertiary hospital and evaluated recommended sepsis scores.

Methods

Patients with an infection and ≥2 SIRS criteria were screened for sepsis by SOFA scoring. From septic patients, socioeconomic and clinical data as well as blood cultures were collected and they were followed until discharge or death; 28-day mortality was determined.

Results

In 170 patients with sepsis, the overall mortality rate was 29.4%. The recognition rate by treating physicians after initial clinical assessment was low (12.4%). Increased risk of mortality was significantly associated with level of SOFA and qSOFA score, Gram-negative bacteremia (in comparison to Gram-positive bacteremia; 42.9 versus 16.7%), and antimicrobial regimen including ceftriaxone (35.7% versus 19.2%) or metronidazole (43.8% versus 25.0%), but not with an increased respiratory rate (≥22/min) or decreased systolic blood pressure (≤100mmHg). In Gram-negative isolates, extended antimicrobial resistance with expression of extended-spectrum beta-lactamase and carbapenemase genes was common. Among adult patients, sensitivity and specificity of qSOFA score for detection of sepsis were 54.3% and 66.7%, respectively.

Conclusion

Sepsis is commonly unrecognized and associated with high mortality, showing the need for reliable and easy-applicable tools to support early recognition. The established sepsis scores were either of limited applicability (SOFA) or, as in the case of qSOFA, were significantly impaired in their sensitivity and specificity, demonstrating the need for further evaluation and adaptation to local settings. Regional factors like malaria endemicity and HIV prevalence might influence the performance of different scores. Ineffective empirical treatment due to antimicrobial resistance is common and associated with mortality. Local antimicrobial resistance statistics are needed for guidance of calculated antimicrobial therapy to support reduction of sepsis mortality.

Investigating the Impact of Early Valve Surgery on Survival in Staphylococcus aureus Infective Endocarditis Using a Marginal Structural Model Approach: Results of a Large, Prospectively Evaluated Cohort

BACKGROUND

The impact of valve surgery on outcomes of Staphylococcus aureus infective endocarditis (SAIE) remains controversial. We tested the hypothesis that early valve surgery (EVS) improves survival by using a novel approach that allows for inclusion of major confounders in a time-dependent way.

METHODS

EVS was defined as valve surgery within 60 days. Univariable and multivariable Cox regression analyses were performed. To account for treatment selection bias, we additionally used a weighted Cox model (marginal structural model) that accounts for time-dynamic imbalances between treatment groups. To address survivor bias, EVS was included as a time-dependent variable. Follow-up of patients was 1 year.

RESULTS

Two hundred and three patients were included in the analysis; 50 underwent EVS. All-cause mortality at day 30 was 26%. In the conventional multivariable Cox regression model, the effect of EVS on the death hazard was 0.85 (95% confidence interval [CI], .47-1.52). Using the weighted Cox model, the death hazard rate (HR) of EVS was 0.71 (95% CI, .34-1.49). In subgroup analyses, no survival benefit was observed in patients with septic shock (HR, 0.80 [CI, .26-2.46]), in NVIE (HR, 0.76 [CI, .33-1.71]) or PVIE (HR, 1.02 [CI, .29-3.54]), or in patients with EVS within 14 days (HR, 0.97 [CI, .46-2.07]).

CONCLUSIONS

Using both a conventional Cox regression model and a weighted Cox model, we did not find a survival benefit for patients who underwent EVS in our cohort. Until results of randomized controlled trials are available, EVS in SAIE should be based on individualized decisions of an experienced multidisciplinary team.

CLINICAL TRIALS REGISTRATION

German Clinical Trials registry (DRKS00005045).

High rate of extended-spectrum beta-lactamase-producing gram-negative infections and associated mortality in Ethiopia: a systematic review and meta-analysis

Background

Extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria have become a serious threat to global health. Their rapid spread is associated with high mortality due to ineffective antibiotic treatment. To date a regular surveillance of multidrug-resistant (MDR) pathogens in Ethiopia is not established. For this report, published data regarding ESBL-producing bacteria in different health facilities of Ethiopia were reviewed.

Methods

This study collates data from published information on the rates and clinical implications of infection with ESBL-producing Gram-negative bacteria in Ethiopia. A systematic literature search was conducted using PubMed, PubMed Central, Medline, Science Direct and Google scholar from October 2018 to March 2019. Eligible studies were identified by applying quality criteria. The pooled proportion of ESBL-producing Gram-negative bacteria was estimated based on a random effect model. The publication bias and the variation in proportion estimates attributed to heterogeneity were assessed.

Results

Fourteen studies with relevant data were included in the review. In total, 1649 Gram-negative bacteria isolated from 5191 clinical samples were included. The pooled proportion estimate of ESBL-producing Gram-negative bacteria was 50% (95% CI: 47.7–52.5%. Data showed a high level of heterogeneity (I² = 95%, P <  0.01). ESBL rates varied by species; 65.7% (263/400) in Klebsiella spp., 48.4% (90/186) in Salmonella spp., and 47.0% (383/815) in E. coli. ESBL-encoding genes were reported in 81 isolates: 67 isolates harbored the CTX-M-1 group and 14 isolates TEM. The mortality associated with infections by bacteria resistant to third generation cephalosporins has rarely been investigated. However, two studies reported a mortality of 33.3% (1/3) and 100% (11/11).

Conclusions

In this meta-analysis, the pooled prevalence of ESBL-producing pathogens is alarmingly high. Data on mortality rates is scarce. This highlights the need for establishing and upgrading clinical microbiology laboratories in Ethiopia for routine antibiotic susceptibility testing and extended surveillance of multidrug resistance.

Defining persistent Staphylococcus aureus bacteraemia: secondary analysis of a prospective cohort study

BACKGROUND

Staphylococcus aureus persistent bacteraemia is only vaguely defined and the effect of different durations of bacteraemia on mortality is not well established. Our primary aim was to analyse mortality according to duration of bacteraemia and to derive a clinically relevant definition for persistent bacteraemia.

METHODS

We did a secondary analysis of a prospective observational cohort study at 17 European centres (nine in the UK, six in Spain, and two in Germany), with recruitment between Jan 1, 2013, and April 30, 2015. Adult patients who were consecutively hospitalised with monomicrobial S aureus bacteraemia were included. Patients were excluded if no follow-up blood culture was taken, if the first follow-up blood-culture was after 7 days, or if active antibiotic therapy was started more than 3 days after first blood culture. The primary outcome was 90-day mortality. Univariable and time-dependent multivariable Cox regression analysis were used to assess predictors of mortality. Duration of bacteraemia was defined as bacteraemic days under active antibiotic therapy counting the first day as day 1.

FINDINGS

Of 1588 individuals assessed for eligibility, 987 were included (median age 65 years [IQR 51-75]; 625 [63%] male). Death within 90 days occurred in 273 (28%) patients. Patients with more than 1 day of bacteraemia (315 [32%]) had higher Charlson comorbidity index and sequential organ failure assessment scores and a longer interval from first symptom to first blood culture. Crude 90-day mortality increased from 22% (148 of 672) with 1 day of bacteraemia, to 39% (85 of 218) with 2-4 days, 43% (30 of 69) with 5-7 days, and 36% (10 of 28) with more than 7 days of bacteraemia. Metastatic infections developed in 39 (6%) of 672 patients with 1 day of bacteraemia versus 40 (13%) of 315 patients if bacteraemia lasted for at least 2 days. The second day of bacteraemia had the highest HR and earliest cutoff significantly associated with mortality (adjusted hazard ratio 1·93, 95% CI 1·51-2·46; p<0·0001).

INTERPRETATION

We suggest redefining the cutoff duration for persistent bacteraemia as 2 days or more despite active antibiotic therapy. Our results favour follow-up blood cultures after 24 h for early identification of all patients with increased risk of death and metastatic infection.

FUNDING

None.

Ultraplexing: increasing the efficiency of long-read sequencing for hybrid assembly with k-mer-based multiplexing

Hybrid genome assembly has emerged as an important technique in bacterial genomics, but cost and labor requirements limit large-scale application. We present Ultraplexing, a method to improve per-sample sequencing cost and hands-on time of Nanopore sequencing for hybrid assembly by at least 50% compared to molecular barcoding while maintaining high assembly quality. Ultraplexing requires the availability of Illumina data and uses inter-sample genetic variability to assign reads to isolates, which obviates the need for molecular barcoding. Thus, Ultraplexing can enable significant sequencing and labor cost reductions in large-scale bacterial genome projects.

Protocol update for the SABATO trial: a randomized controlled trial to assess early oral switch therapy in low-risk Staphylococcus aureus bloodstream infection

BACKGROUND

SABATO (Staphylococcus aureus bacteremia antibiotic treatment options) is a randomized, parallel-group, clinical non-inferiority trial designed to examine the efficacy and safety of early oral switch therapy in low-risk Staphylococcus aureus infection. The original trial protocol was published in Trials (accessible at https://doi.org/10.1186/s13063-015-0973-x ). Here we describe final amendments to the study protocol and discuss the underlying rationale.

METHODS/DESIGN

Three major changes were introduced into the study protocol: (1) the inclusion and exclusion criteria were refined so that patients with certain comorbidities (end-stage renal disease, severe liver disease) and uninfected foreign bodies (orthopedic prosthesis, pacemaker, implanted cardiac cardioverter-defibrillator) became eligible for enrollment under certain conditions; (2) the target sample size was decreased by choosing a conventional non-inferiority margin of 10% and converting the interim analysis (215 patients) into the final analysis; and (3) an additional follow-up visit after 30 days was introduced to allow for a closer follow-up of patients.

CONCLUSION

Changes to the study protocol were introduced to improve the enrollment and follow-up of patients. Furthermore, the decrease of the sample size will facilitate completion of the trial.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01792804. Registered on 13 February 2013. German Clinical trials register, DRKS00004741. Registered on 4 October 2013, EudraCT 2013-000577-77.

Influence of Acetylsalicylic Acid Use on Risk and Outcome of Community-Acquired Staphylococcus aureus Bacteremia: A Population-Based Study

Objective

To investigate the influence of acetylsalicylic acid (ASA) use on risk and outcome of community-acquired Staphylococcus aureus bacteremia (CA-SAB).

Method

We used population-based medical databases to identify all patients diagnosed in northern Denmark with first-time CA-SAB and matched population controls from 2000–2011. Categories for ASA users included current users (new or long-term users), former users, and nonusers. The analyses were adjusted for comorbidities, comedication use, and socioeconomic indicators.

Results

We identified 2638 patients with first-time CA-SAB and 26 379 matched population controls. Compared with nonusers, the adjusted odds ratio (aOR) for CA-SAB was 1.00 (95% confidence interval [CI], 0.88–1.13) for current users, 1.00 (95% CI, 0.86–1.16) for former users, 2.04 (95% CI, 1.42–2.94) for new users, and 0.95 (95% CI, 0.84–1.09) for long-term users. Thirty-day cumulative mortality was 28.0% among current users compared with 21.6% among nonusers, yielding an adjusted hazard rate ratio (aHRR) of 1.02 (95% CI, 0.84–1.25). Compared with nonusers, the aHRR was 1.10 (95% CI, 0.87–1.40) for former users, 0.60 (95% CI, 0.29–1.21) for new users, and 1.06 (95% CI, 0.87–1.31) for long-term users. We observed no difference in the risk or outcome of CA-SAB with increasing ASA dose or by presence of diseases commonly treated with ASA.

Conclusions

Use of ASA did not seem to influence the risk or outcome of CA-SAB. The apparent increased risk among new users may relate to residual confounding from the circumstances underlying ASA treatment initiation. Our finding of no association remained robust with increasing ASA dose and across multiple patient subsets.

Effect of Clinically Uninfected Orthopedic Implants and Pacemakers/AICDs in Low-Risk Staphylococcus aureus Bloodstream Infection on Crude Mortality Rate: A Post Hoc Analysis of a Large Cohort Study

Background

The standard treatment duration in low-risk Staphylococcus aureus bloodstream (SAB) is 14 days. However, it is unclear whether an extended course of antimicrobial therapy is necessary in patients with clinically uninfected prosthetic joints/osteosyntheses or pacemakers/automated implanted cardioverter-defibrillators (AICDs). Thus, we compared the duration of antimicrobial therapy and outcomes in patients with and those without clinically uninfected foreign bodies.

Methods

We conducted a post hoc analysis of data from the prospective Invasive Staphylococcus aureus Infection Cohort (INSTINCT) study. Adult low-risk patients who survived ≥4 days were assessed for duration of treatment, SAB-related events (attributable death, relapse, or new deep-seated infection), and survival.

Results

Of the 1288 patients enrolled, 292 satisfied criteria for low-risk SAB. Forty-three patients (15%) had a clinically uninfected pacemaker/AICD or orthopedic implant. Patients with foreign bodies were significantly older (mean age, 72 vs 62 years for those without; P < .001; P = .9) and had a higher Charlson score (median, 3 vs 2; P = .06). The total duration of antimicrobial therapy (median, 18 vs 17 days, respectively; P = .7), all-cause mortality rate (16% vs 14%; P = .7), and prevalence of SAB-related events within 90 days were similar (2% vs 2%) in the 2 groups. At 1-year follow-up, SAB-related events were more frequent in patients with foreign bodies (7% vs 4% in those without; P = .4) (hazard ratio, 1.41; 95% confidence interval, .35–5.69; in a multivariable Cox model), but this difference was not statistically significant.

Conclusions

Low-risk patients with clinically uninfected foreign bodies received a similar duration of antimicrobial therapy without a significant impact on mortality rate. The observed higher hazard ratio of SAB-related events within 1 year necessitates additional studies before recommendations concerning treatment duration in this patient subgroup can be adapted or modified.

[Staphylococcus aureus Bacteraemia - an Interdisciplinary Challenge]

BACKGROUND

Staphylococcus aureus is the second-most-common pathogen among bloodstream infections. Due to a high hospital mortality rate (15 - 40%), frequent complications and recurrences the clinical management of Staphylococcus aureus bacteremia (SAB) is distinct from bacteremia from other pathogens.

METHODS

A literature search was performed using PubMed. Guidelines and best practice expert recommendations were included.

RESULTS

The detection of S. aureus in blood culture should always be considered clinically relevant. The drug of choice for treatment of a bloodstream infection with methicillin-sensitive S. aureus is flucloxacillin (8 - 12 g i. v./d). In a bloodstream infection with methicillin-resistant S. aureus (MRSA) vancomycin or daptomycin (the latter not in pneumonic focus) are recommended. Follow-up blood cultures, source identification, including transoesophageal echocardiography in patients with risk profile, and rapid source control are important measures. The duration of therapy is at least 14 days with uncomplicated SAB, whereby the entire therapy should be carried out intravenously. In case of complicated SAB, a total therapy duration of at least 4 - 6 weeks is recommended. Adherence to this set of measures can reduce mortality by up to 50%.

CONCLUSION

SAB is associated with high morbidity and mortality. Clinical management is complex. By adhering to diagnostic and therapeutic measures, the prognosis can be improved.

Survival following Staphylococcus aureus bloodstream infection: A prospective multinational cohort study assessing the impact of place of care

BACKGROUND

Staphylococcus aureus bloodstream infection (SAB) is a common, life-threatening infection with a high mortality. Survival can be improved by implementing quality of care bundles in hospitals. We previously observed marked differences in mortality between hospitals and now assessed whether mortality could serve as a valid and easy to implement quality of care outcome measure.

METHODS

We conducted a prospective observational study between January 2013 and April 2015 on consecutive, adult patients with SAB from 11 tertiary care centers in Germany, South Korea, Spain, Taiwan, and the United Kingdom. Factors associated with mortality at 90 days were analyzed by Cox proportional hazards regression and flexible parametric models.

RESULTS

1851 patients with a median age of 66 years (64% male) were analyzed. Crude 90-day mortality differed significantly between hospitals (range 23-39%). Significant variation between centers was observed for methicillin-resistant S. aureus, community-acquisition, infective foci, as well as measures of comorbidities, and severity of disease. In multivariable analysis, factors independently associated with mortality at 90 days were age, nosocomial acquisition, unknown infective focus, pneumonia, Charlson comorbidity index, SOFA score, and study center. The risk of death varied over time differently for each infective focus. Crude mortality differed markedly from adjusted mortality.

DISCUSSION

We observed significant differences in adjusted mortality between hospitals, suggesting differences in quality of care. However, mortality is strongly influenced by patient mix and thus, crude mortality is not a suitable quality indicator.

Long-Term, Low-Frequency Cluster of a German-Imipenemase-1-Producing Enterobacter hormaechei ssp. steigerwaltii ST89 in a Tertiary Care Hospital in Germany

Enterobacter cloacae complex is a common cause of hospital outbreaks. A retrospective and prospective molecular analysis of carbapenem-resistant clinical isolates in a tertiary care center demonstrated an outbreak of a German-imipenemase-1 (GIM-1) metallo-beta-lactamase-producing Enterobacter hormaechei ssp. steigerwaltii affecting 23 patients between 2009 and 2016. Thirty-three isolates were sequence type 89 by conventional multilocus sequence typing (MLST) and displayed a maximum difference of 49 out of 3,643 targets in the ad-hoc core-genome MLST (cgMLST) scheme (SeqSphere+ software; Ridom, Münster, Germany). The relatedness of all isolates was confirmed by further maximum-likelihood phylogeny. One clonal complex of highly related isolates (≤15 allele difference in cgMLST) contained 17 patients, but epidemiological data only suggested five transmission events. The bla_GIM-1-gene was embedded in a class-1-integron (In770) and the Tn21-subgroup transposon Tn6216 (KC511628) on a 25-kb plasmid. Environmental screening detected one colonized sink trap in a service room. The outbreak was self-limited as no further bla_GIM-1-positive E. hormaechei has been isolated since 2016. Routine molecular screening of carbapenem-nonsusceptible gram-negative isolates detected a long-term, low-frequency outbreak of a GIM-1-producing E. hormaechei ssp. steigerwaltii clone. This highlights the necessity of molecular surveillance.

Determining vancomycin Etest MICs in patients with MRSA bloodstream infection does not support switching antimicrobials

OBJECTIVES

Elevated vancomycin minimum inhibitory concentrations (MIC) have been reported to adversely affect clinical outcome in methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI). We therefore examined the association between vancomycin MIC and outcome considering various potential confounders.

METHODS

Clinical data and bacterial isolates were prospectively collected from patients with MRSA BSI from 2006 to 2012 as part of the Invasive Staphylococcus aureus Infection Cohort (INSTINCT) study. Antimicrobial susceptibility was assessed by Etest, broth microdilution (BMD) and VITEK 2. Bacterial genotypes were determined by spa typing. Using univariate and Cox regression analyses, we investigated the impact of low (≤1.0 mg/L) and high (≥1.5 mg/L) vancomycin Etest MIC on clinical outcomes.

RESULTS

Ninety-one MRSA BSI episodes were included, of which 79 (86.8%) were caused by spa types t003, t032 and t045. High vancomycin MICs were seen only if using Etest but not confirmed using standard reference BMD. When episodes were stratified into low and high vancomycin Etest MIC groups, 30-day overall mortality was 34.5% and 27.3%, respectively (P = 0.64, OR 0.71; 95% confidence interval [CI] 0.27-1.79). Variables significantly associated with all-cause mortality in the Cox model were age (P = 0.003), acute physiology score (P = 0.0006), and Charlson comorbidity index (P = 0.018).

CONCLUSIONS

Vancomycin MICs may vary dependent on testing methodologies and local MRSA epidemiology. The patients' underlying disease and individual comorbidities rather than elevated vancomycin MICs determine adverse clinical outcomes in MRSA BSI. Routine Etest MIC testing of MRSA isolates is of limited value for treatment decisions.

Oritavancin: a long-acting antibacterial lipoglycopeptide

Oritavancin is a new lipoglycopeptide antibacterial agent with an exceptionally long terminal half-life and a rapid bactericidal effect. Multiple mechanisms of action lead to a broad activity against Gram-positive bacteria, such as staphylococci, streptococci and enterococci, including methicillin-resistant Staphylococcus aureus. Its long terminal half-life allows for single-dose treatment of acute bacterial skin and skin structure infections. Oritavancin was found to be safe and effective in treating acute bacterial skin and skin structure infections in adults and it is currently approved in the USA and in Europe for this indication. Unfortunately, data for other indications are lacking. Here, we review chemistry, microbiology, pharmacology, efficacy and tolerability of oritavancin.

Use of Glucocorticoids and Risk of Community-Acquired Staphylococcus aureus Bacteremia: A Population-Based Case-Control Study

OBJECTIVE

To investigate whether the use of systemic glucocorticoids is a risk factor for community-acquired Staphylococcus aureus bacteremia (CA-SAB).

PATIENTS AND METHODS

We used population-based medical registries in Northern Denmark to conduct a case-control study including all adults with first-time CA-SAB and matched population controls from January 1, 2000, through December 31, 2011. Glucocorticoid users were categorized as current users (new or long-term use), former users, and nonusers. Using conditional logistic regression, we computed odds ratios (ORs) of CA-SAB according to glucocorticoid exposure, overall and by 90-day prednisolone-equivalent cumulative dose.

RESULTS

We identified 2638 patients with first-time CA-SAB and 26,379 matched population controls. Current glucocorticoid users experienced considerably increased risk of CA-SAB compared with nonusers (adjusted OR=2.48; 95% CI, 2.12-2.90). The adjusted OR was 2.73 (95% CI, 2.17-3.45) in new users, 2.31 (95% CI, 1.90-2.82) in long-term users, and much lower at 1.33 (95% CI, 0.98-1.81) in former users of glucocorticoids compared with nonusers. The risk of CA-SAB increased with higher 90-day cumulative doses. Compared with nonusers of glucocorticoids, the adjusted OR was 1.32 (95% CI, 1.01-1.72) for persons with a cumulative dose of 150 mg or less, 2.42 (95% CI, 1.76-3.33) for persons whose cumulative dose was greater than 500 to 1000 mg, and 6.25 (95% CI, 4.74-8.23) for persons with a cumulative dose greater than 1000 mg.

CONCLUSION

Glucocorticoid use was associated with a substantially increased risk of CA-SAB. The risk increased with higher cumulative dose, revealing a distinct dose-response relation.

Gender differences in the outcome of community-acquired Staphylococcus aureus bacteraemia: a historical population-based cohort study

OBJECTIVES

Female gender has been suggested to be associated with poor outcome in patients with Staphylococcus aureus bacteraemia (SAB), but existing data remain sparse and conflicting. We investigated clinical outcomes in female and male patients with community-acquired (CA-) SAB.

METHODS

Population-based medical registers were used to conduct a cohort study of all adult patients with CA-SAB in northern Denmark, 2000-2011. Thirty-day mortality after CA-SAB for female and male patients was estimated by the Kaplan-Meier method. Using Cox proportional hazards regression, we computed hazard ratios (HRs) of death according to gender, overall and stratified by age groups, co-morbidity level, and selected major diseases while adjusting for potential confounders. Moreover, we estimated 30-day prevalence proportions for SAB-associated infective endocarditis and osteomyelitis by gender.

RESULTS

Among 2638 patients with CA-SAB, 1022 (39%) were female. Thirty-day mortality was 29% (n = 297) in female patients and 22% (n = 355) in male patients, yielding an adjusted HR (aHR) of 1.30 (95% CI, 1.11-1.53). This association appeared robust across age groups, whereas no consistent pattern was observed according to co-morbidity level. Compared with male patients, the prognostic impact of gender was most pronounced among female patients with diabetes (aHR 1.52; 95% CI 1.04-2.21)), and among female patients with cancer (aHR 1.40; 95% CI 1.04-1.90). The 30-day prevalence of infective endocarditis or osteomyelitis did not differ according to gender.

CONCLUSION

Female patients with CA-SAB experienced increased 30-day mortality compared with male patients. Gender should be considered in the triage and risk stratification of CA-SAB patients.

Polymorphisms in Fibronectin Binding Proteins A and B among Staphylococcus aureus Bloodstream Isolates Are Not Associated with Arthroplasty Infection

Background

Nonsynonymous single nucleotide polymorphisms (SNPs) in fibronectin binding protein A (fnbA) of Staphylococcus aureus are associated with cardiac device infections. However, the role of fnbA SNPs in S. aureus arthroplasty infection is unknown.

Methods

Bloodstream S. aureus isolates from a derivation cohort of patients at a single U.S. medical center with S. aureus bacteremia (SAB) and prosthetic hip or knee arthroplasties that were infected (PJI, n = 27) or uninfected (PJU, n = 43) underwent sequencing of fnbA and fnbB. A validation cohort of S. aureus bloodstream PJI (n = 12) and PJU (n = 58) isolates from Germany also underwent fnbA and fnbB sequencing.

Results

Overall, none of the individual fnbA or fnbB SNPs were significantly associated with the PJI or PJU clinical groups within the derivation cohort. Similarly, none of the individual fnbA or fnbB SNPs were associated with PJI or PJU when the analysis was restricted to patients with either early SAB (i.e., bacteremia occurring <1 year after placement or manipulation of prostheses) or late SAB (i.e., bacteremia >1 year after placement or manipulation of prostheses).

Conclusions

In contrast to cardiac device infections, there is no association between nonsynonymous SNPs in fnbA or fnbB of bloodstream S. aureus isolates and arthroplasty infection. These results suggest that initial steps leading to S. aureus infection of cardiovascular and orthopedic prostheses may arise by distinct processes.

Early oral switch therapy in low-risk Staphylococcus aureus bloodstream infection (SABATO): study protocol for a randomized controlled trial

Background

Current guidelines recommend that patients with Staphylococcus aureus bloodstream infection (SAB) are treated with long courses of intravenous antimicrobial therapy. This serves to avoid SAB-related complications such as relapses, local extension and distant metastatic foci. However, in certain clinical scenarios, the incidence of SAB-related complications is low. Patients with a low-risk for complications may thus benefit from an early switch to oral medication through earlier discharge and fewer complications of intravenous therapy.

The major objective for the SABATO trial is to demonstrate that in patients with low-risk SAB a switch from intravenous to oral antimicrobial therapy (oral switch therapy, OST) is non-inferior to a conventional course of intravenous therapy (intravenous standard therapy, IST).

Methods/Design

The trial is designed as randomized, parallel-group, observer-blinded, clinical non-inferiority trial. The primary endpoint is the occurrence of a SAB-related complication (relapsing SAB, deep-seated infection, and attributable mortality) within 90 days. Secondary endpoints are the length of hospital stay; 14-day, 30-day, and 90-day mortality; and complications of intravenous therapy. Patients with SAB who have received 5 to 7 full days of adequate intravenous antimicrobial therapy are eligible. Main exclusion criteria are polymicrobial bloodstream infection, signs and symptoms of complicated SAB (deep-seated infection, hematogenous dissemination, septic shock, and prolonged bacteremia), the presence of a non-removable foreign body, and severe comorbidity. Patients will receive either OST or IST with a protocol-approved antimicrobial and are followed up for 90 days. Four hundred thirty patients will be randomized 1:1 in two study arms. Efficacy regarding incidence of SAB-related complications is tested sequentially with a non-inferiority margin of 10 and 5 percentage points.

Discussion

The SABATO trial assesses whether early oral switch therapy is safe and effective for patients with low-risk SAB. Regardless of the result, this pragmatic trial will strongly influence the standard of care in SAB.

Trial registration

ClinicalTrials.gov NCT01792804 registered 13 February 2013; German Clinical trials register DRKS00004741 registered 4 October 2013, EudraCT 2013-000577-77. First patient randomized on 20 December 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-0973-x) contains supplementary material, which is available to authorized users.

Amino acid alterations in fibronectin binding protein A (FnBPA) and bacterial genotype are associated with cardiac device related infection in Staphylococcus aureus bacteraemia

OBJECTIVES

Staphylococcus aureus initiates cardiac device-related infection (CDI) by binding of fibronectin binding protein A (FnBPA) to the device's surface. In FnBPA, specific "binding enhancing" amino acid alterations are associated with CDI. However, no study has investigated whether these mutations also occur in geographically different regions and whether they arise during infection or are inherent properties of the infecting isolate.

METHODS

We analysed bacterial isolates from 34 patients with S. aureus bacteraemia and implanted cardiac devices for association with CDI, FnBPA sequence, classification into a clonal complex (CC), and binding to fibronectin (Fn).

RESULTS

We confirmed that amino acid alterations at positions 652, 782, and 786 in FnBPA were associated with CDI (p = 0.005). Furthermore, CC15 and CC45 isolates were associated with CDI (p = 0.004). All isolates within a CC exhibited a characteristic mutation pattern, with major changes occurring in CC45 including a duplication of D1 and an altered immunogenic epitope in the D3 repeat. Isolates harbouring the "binding enhancing" mutations showed a slightly increased Fn binding capability, whereas Fn binding was decreased in CC45 isolates, according to a microtiter plate assay.

CONCLUSIONS

FnBPA sequence variations are lineage specific and display inherent properties of the infecting isolate. Sequence analysis of FnBPA, as well as the bacterial genotype, may be used to predict the risk for device-related infection.

Staphylococcus aureus bloodstream infection: a pooled analysis of five prospective, observational studies

OBJECTIVES

Staphylococcus aureus bacteraemia is a common, often fatal infection. Our aim was to describe how its clinical presentation varies between populations and to identify common determinants of outcome.

METHODS

We conducted a pooled analysis on 3395 consecutive adult patients with S. aureus bacteraemia. Patients were enrolled between 2006 and 2011 in five prospective studies in 20 tertiary care centres in Germany, Spain, United Kingdom, and United States.

RESULTS

The median age of participants was 64 years (interquartile range 50-75 years) and 63.8% were male. 25.4% of infections were associated with diabetes mellitus, 40.7% were nosocomial, 20.6% were caused by methicillin-resistant S. aureus (MRSA), although these proportions varied significantly across studies. Intravenous catheters were the commonest identified infective focus (27.7%); 8.3% had endocarditis. Crude 14 and 90-day mortality was 14.6% and 29.2%, respectively. Age, MRSA bacteraemia, nosocomial acquisition, endocarditis, and pneumonia were independently associated with death, but a strong association was with an unidentified infective focus (adjusted hazard ratio for 90-day mortality 2.92; 95% confidence interval 2.33 to 3.67, p < 0.0001).

CONCLUSION

The baseline demographic and clinical features of S. aureus bacteraemia vary significantly between populations. Mortality could be reduced by assiduous MRSA control and early identification of the infective focus.

Microarray-based genotyping and clinical outcomes of Staphylococcus aureus bloodstream infection: an exploratory study

The clinical course of Staphylococcus aureus bacteremia varies extensively. We sought to determine the relationship between genetic characteristics of the infecting pathogen and clinical outcomes in an exploratory study. In two study centers, 317 blood culture isolates were analyzed by DNA microarray and spa genotyping. By uni- and multivariate regression analyses associations of genotype data with 30-day all-cause mortality, severe sepsis/septic shock, disseminated disease, endocarditis, and osteoarticular infection were investigated. Univariate analysis showed significant association between S. aureus genes/gene-clusters or clonal complexes and clinical endpoints. For example CC15 was associated with 30-day mortality and CC22 with osteoarticular infection. In multivariate analysis methicillin resistance (mecA, OR 4.8 [1.43–16.06]) and the beta-lactamase-gene (bla, OR 3.12 [1.17–8.30]) remained independently associated with 30-day mortality. The presence of genes for enterotoxins (sed/sej/ser) was associated with endocarditis (OR 5.11 [1.14–18.62]). Host factors such as McCabe classification (OR 4.52 [2.09–9.79] for mortality), age (OR 1.06 [1.03–1.10] per year), and community-acquisition (OR 3.40 [1.31–8.81]) had a major influence on disease severity, dissemination and mortality. Individual genotypes and clonal complexes of S. aureus can only partially explain clinical features and outcomes of S. aureus bacteremia. Genotype-phenotype association studies need to include adjustments for host factors like age, comorbidity and community-acquisition.

Non-culture-based methods to diagnose bloodstream infection: Does it work?

Bloodstream infections are a major cause of morbidity and mortality worldwide. Molecular methods for the detection of pathogens in blood have been developed. The clinical utility of these methods and their integration into the clinical workflow is discussed.