Incidence of bloodstream infection: a review of population-based studies

Prevalence, misclassification, and clinical consequences of the heteroresistant phenotype in Escherichia coli bloodstream infections in patients in Uppsala, Sweden: a retrospective cohort study

BACKGROUND

Antibiotic heteroresistance is a common bacterial phenotype characterised by the presence of small resistant subpopulations within a susceptible population. During antibiotic exposure, these resistant subpopulations can be enriched and potentially lead to treatment failure. In this study, we examined the prevalence, misclassification, and clinical effect of heteroresistance in Escherichia coli bloodstream infections for the clinically important antibiotics cefotaxime, gentamicin, and piperacillin-tazobactam.

METHODS

We conducted a retrospective cohort analysis of patients (n=255) admitted to in-patient care and treated for E coli bloodstream infections within the Uppsala region in Sweden between Jan 1, 2014, and Dec 31, 2015. Patient inclusion criteria were admission to hospital on suspicion of infection, starting systemic antibiotics at the time of admission, positive blood cultures for the growth of E coli upon admission, and residency in the Uppsala health-care region at the time of admission. Exclusion criteria were growth of an additional pathogen than E coli in blood cultures taken at admission or previous inclusion of the patients in the study for another bloodstream infection. Antibiotic susceptibility of preserved blood culture isolates of E coli was assessed for cefotaxime, gentamicin, and piperacillin-tazobactam by disk diffusion and breakpoint crossing heteroresistance (BCHR) was identified using population analysis profiling. The clinical outcome parameters were obtained from patient records. The primary outcome variable was length of hospital stay due to the E coli bloodstream infection, defined as the time between admission and discharge from inpatient care as noted on the physician's notes. Secondary outcomes were time to fever resolution, admission to intermediary care unit or intensive care unit during time in hospital, switching or adding another intravenous antibiotic treatment, re-admission to hospital within 30 days of original admission, recurrent E coli infection within 30 days of admission to hospital, and all-cause mortality within 90 days of admission.

FINDINGS

A total of 255 participants with a corresponding E coli isolate (out of 500 screened for eligibility) met the inclusion criteria, with 135 female patients and 120 male patients. One (<1%) of 255 strains was BCHR for cefotaxime, 109 (43%) of 255 strains were BCHR for gentamicin, and 22 (9%) of 255 strains were BCHR for piperacillin-tazobactam. Clinical susceptibility testing misclassified 120 (96%) of 125 heteroresistant bacterial strains as susceptible. The BCHR phenotypes had no correlation to length of hospital stay due to the E coli bloodstream infection. However, patients with piperacillin-tazobactam BCHR strains who received piperacillin-tazobactam had 3·1 times higher odds for admittance to the intermediate care unit (95% CI 1·1-9·6, p=0·041) than the remainder of the cohort, excluding those treated with gentamicin. Similarly, those infected with gentamicin BCHR who received gentamicin showed higher odds for admittance to the intensive care unit (5·6 [1·1-42·0, p=0·043]) and mortality (7·1 [1·2-49·2, p=0·030]) than patients treated with gentamicin who were infected with non-gentamicin BCHR E coli.

INTERPRETATION

In a cohort of patients with E coli bloodstream infections, heteroresistance is common and frequently misidentified in routine clinical testing. Several negative effects on patient outcomes are associated with heteroresistant strains.

FUNDING

Wallenberg Foundation, Swedish Research Council, and US National Institutes Of Health.

Review on biphasic blood drying method for rapid pathogen detection in bloodstream infections

Rapid and accurate detection of pathogenic microorganisms in blood is critical for diagnosing life-threatening conditions such as bloodstream infections (BSIs). Current methods for the detection and identification of bacteria from large volumes of blood (5 mL) involve culture steps followed by DNA extraction/purification/concentration and Polymerase Chain Reaction (PCR)-based nucleic acid amplification. DNA extraction and amplification directly from blood samples is hampered by the complexity of the blood matrix, resulting in time-consuming and labor-intensive processes. This review delves into recent advancements in molecular diagnostics based on blood drying, coined as 'biphasic reaction', and highlights this new technique that attempts to overcome the limitations of traditional sample preparation and amplification processes. The biphasic blood drying method, in combination with isothermal amplification methods such as loop-mediated isothermal amplification (LAMP) or recombinase polymerase amplification (RPA), has recently been shown to improve the sensitivity of detection of bacterial, viral, and fungal pathogens from ∼1 mL of whole blood, while minimizing DNA loss and avoiding the use of extraction/purification/concentration kits. Furthermore, the biphasic approach in combination with LAMP has been shown to be a culture-free method capable of detecting bacteria in clinical samples with a sensitivity of ∼1 CFU/mL in ∼2.5 h. This represents a significant reduction in detection and identification time compared to current clinical procedures based on bacterial culture prior to PCR amplification. This review paper aims to be a guide to identify new opportunities for future advancements and applications of the biphasic technology.

Blood culture time to positivity in pediatric patients with bloodstream infection in rural Gambia

Objectives

There is a lack of data on the time to blood culture positivity (TTP) in pediatric populations in low-income countries. We aimed to assess the host and pathogen factors associated with TTP in children aged under 5 years in rural Gambia.

Methods

Between September 2019 and December 2023, we collected blood cultures from children under 5 years with suspected bloodstream infections. We determined the TTP from the time of culture incubation to when bacterial growth was first detected.

Results

Overall, 547 invasive bacteria pathogens were evaluated. The median TTP was 19.2 hours and 70%, 76%, 89%, and 96% of cases had TTP at 24, 36, 48, and 72 hours, respectively. Streptococcus pneumoniae had the shortest median TTP (17.4 hours), whereas Neisseria species had the longest (45 hours). TTP was dependent on the pathogen and independent of age, sex, temperature, clinical outcome, nutritional status, and length of hospital stay. Gram-positive bacteria had shorter TTP than gram-negative bacteria (18.6 vs 19.6 hours, P < 0.01).

Conclusions

In rural Gambia, most blood cultures from pediatric patients would turn positive within 48 hours of incubation. A maximum of 48 hours of observation after the commencement of antibiotic therapy in hospitalized children may be sufficient for clinicians to receive feedback on blood culture results.

Investigation of methicillin, beta lactam, carbapenem, and multidrug resistant bacteria from blood cultures of septicemia suspected patients in Northwest Ethiopia

The presence of microorganisms in the bloodstream can result in severe, potentially life-threatening conditions, which are a significant cause of morbidity and mortality worldwide. The rise of antimicrobial-resistant strains further exacerbates these outcomes. However, the data concerning bacterial profiles and resistance to antimicrobials, particularly against extended-spectrum beta-lactams and carbapenems, are limited. Aimed to characterize pathogens isolated from positive blood cultures, including bacterial profiles and antibiotic susceptibility patterns, and to identify predictors of blood culture positivity in septicemia-suspected patients at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia. A hospital-based cross-sectional study was conducted from February 15 to May 30, 2023. The study involved 341 patients suspected of having septicaemia who were selected consecutively through a convenience sampling technique. Blood samples were collected aseptically from each patient (10 ml from adults, 5 ml from children, and 1 ml from neonates) and inoculated into bottles containing tryptic soy broth in volumes appropriate for the patient's age. The samples were incubated at 35-37 °C for up to 7 days to detect bacterial growth. Positive blood cultures were subcultured onto various media, including chocolate agar, blood agar, modified Thayer-Martin agar, MacConkey agar, and mannitol salt agar, and incubated again at 35-37 °C for 24 h. The suspected bacteria were identified on the basis of colony morphology, Gram staining, and biochemical tests. Antimicrobial susceptibility testing was conducted via both the Kirby-Bauer and modified Kirby-Bauer disk diffusion methods. Resistance to methicillin, extended-spectrum beta-lactams, and carbapenems was determined via the cefoxitin disc test, combined-disk diffusion method, and modified carbapenem inactivation method, respectively. The data were entered into Epi-Data version 4.6 and analysed via SPSS version 25. Binary logistic regression analyses were employed to identify factors associated with bloodstream infections (BSI), with a P value of less than 0.05 considered statistically significant. Out of 341 patients suspected of septicemia, 196 (57.5%) were male and 145 (42.5%) were female, with a mean (± SD) age of 16.5 (± 7.5) years. Bloodstream infection was identified in 87 (25.5%) patients (95% CI: 21.1-30.4). Among these positive cases, 67 (77%) were from ward patients, while 20 (23%) were from those visiting outpatient departments. The primary gram-positive bacteria identified included S. aureus 27 (31.0%), CoNS 14 (16.1%), S. viridans 8 (9.2%), and S. agalactiae 4 (4.6%). The gram-negative isolates were predominantly K. pneumoniae 11 (12.6%), followed by E. coli 9 (10.3%), E. cloacae 6 (6.9%), Acinetobacter spp. 3 (3.5%), N. meningitidis 3 (3.5%), and P. aeruginosa 2 (2.3%). Methicillin resistance was detected in 17/27 (63.0%) S. aureus strains and 2/14 (14.3%) CoNS strains. Multidrug resistance was detected in 63/87 (72.4%, 95% CI: 67.2-84.7%) of the isolates. Extended-spectrum beta-lactamase and carbapenemase production were observed in 12/31 (38.7%) and 5/31 (16.1%) of isolates, respectively. The factors associated with BSI were the presence of wounds and burns (AOR = 2.103, 95% CI: 1.365-3.241, P = 0.041), length of hospital stay (≥ 5) (AOR = 2.209, 95% CI: 1.122-4.347, P = 0.022), and prior medical procedures (AOR = 1.982, 95% CI: 1.125-3.492, P = 0.018). Bloodstream infection was identified in 25.5% of suspected septicemia cases, with multidrug-resistant bacteria present in 72.4% of isolates. Gram-positive bacteria, particularly S. aureus, and gram-negative bacteria like K. pneumoniae and E. coli were predominant. High rates of methicillin, beta-lactam, and carbapenem resistance were observed, emphasizing the magnitude of antimicrobial resistance. Risk factors such as wounds, extended hospital stays, and prior medical procedures significantly increased the likelihood of culture positivity. This suggests the need for regular antimicrobial susceptibility testing to guide antibiotic selection and track resistance trends, proper wound care and medical device usage to reduce the risk of BSI in healthcare settings.

Hospital-Acquired Bloodstream Infections in Relation to Intensive Care Unit Stays During Hospitalization-A Population-Based Cohort Study

Background: Little is known about the clinical characteristics and pathogens causing hospital-acquired bloodstream infections (HA-BSIs) in relation to an intensive care unit (ICU) stay. Methods: Population-based cohort study, comprising 35% of the Danish population, 2009-2016. We derived four patient groups with first-time HA-BSIs: no ICU stay during the admission (non-ICU patients) and HA-BSI acquired before, in, or after an ICU stay (before-ICU, in-ICU, and after-ICU patients). These groups were compared in relation to microbiological and clinical characteristics, including 28- and >28-day mortality. Results: Among 6888 HA-BSI patients, 4017, 792, 1388, and 691 were non-ICU, before-ICU, in-ICU, and after-ICU, respectively. The rates of several microorganisms differed between the patient groups, e.g., Enterococci (9.4% of non-ICU and 32.0% of in-ICU patients). The 28-day mortality was 26.3% in non-ICU, 45.0% in before-ICU, 35.6% in in-ICU, and 19.0% in after-ICU patients. The corresponding adjusted hazard ratios (95% confidence interval) were 2.10 (1.85-2.36), 1.67 (1.50-1.87), and 0.76 (0.63-0.91) (reference: non-ICU patients). There were few differences as regards >28-day mortality. Conclusions: We found large differences between common microorganisms and prognosis between the four patient groups. After-ICU patients had the lowest 28-day mortality despite age and comorbidity characteristics similar to the other three groups.

Staphylococcus aureus Dissemination Presenting With Encephalopathy and Epidural Abscess

Background: Staphylococcal infection is a common bacterial disease with common clinical features. Untreated infection, especially in immunosenescence cases, can affect other organs. This can lead to multiorgan dysfunction and cause increased morbidity and mortality. Unlike commonly presented features of pneumonia, dissemination of infection can pose diagnostic and therapeutic enigma. Therefore, any such presentation in common clinical practice can yield a conundrum of diagnoses. Case Report: A 69-year-old elderly male presented to the Emergency Department with acute onset encephalopathy. Historically, cues were limited, and evaluation was negated for acute cerebrovascular event or seizure. Laboratory findings were suggestive of a severe sepsis. While clinical medicine workup and diagnostic dilemma were ongoing, possible sources of the sepsis were thoroughly sought including range of infectious causes. This patient's presentation was one of its kind: staphylococcal bacteremia seeding to cause pneumonia and unusual epidural abscess in due course of illness. Conclusion: The health outcome of the critically ill especially elderly patients depends mostly on the importance of clinical medicine to address the diagnostic enigma and virtue of supportive care delivered. Staphylococcus aureus infections are capable of developing distant infectious foci, as highlighted in this case, and that the clinician should be alert to this possibility. This particular case firmly posits an admonition for clinicians and the importance of clinical medicine for critical reasoning to improve the patient outcome.

An ovine septic shock model of live bacterial infusion

BACKGROUND

Escherichia coli is the most common cause of human bloodstream infections and bacterial sepsis/septic shock. However, translation of preclinical septic shock resuscitative therapies remains limited mainly due to low-fidelity of available models in mimicking clinical illness. To overcome the translational barrier, we sought to replicate sepsis complexity by creating an acutely critically-ill preclinical bacterial septic shock model undergoing active 48-h intensive care management.

AIM

To develop a clinically relevant large-animal (ovine) live-bacterial infusion model for septic shock.

METHODS

Septic shock was induced by intravenous infusion of the live antibiotic resistant extra-intestinal pathogenic E. coli sequence type 131 strain EC958 in eight anesthetised and mechanically ventilated sheep. A bacterial dose range of 2 × 105-2 × 109 cfu/mL was used for the dose optimisation phase (n = 4) and upon dose confirmation the model was developed (n = 5). Post-shock the animals underwent an early-vasopressor and volume-restriction resuscitation strategy with active haemodynamic management and monitoring over 48 h. Serial blood samples were collected for testing of pro-inflammatory (IL-6, IL-8, VEGFA) and anti-inflammatory (IL-10) cytokines and hyaluronan assay to assess endothelial integrity. Tissue samples were collected for histopathology and transmission electron microscopy.

RESULTS

The 2 × 107 cfu/mL bacterial dose led to a reproducible distributive shock within a pre-determined 12-h period. Five sheep were used to demonstrate consistency of the model. Bacterial infusion led to development of septic shock in all animals. The baseline mean arterial blood pressure reduced from a median of 91 mmHg (71, 102) to 50 mmHg (48, 57) (p = 0.004) and lactate levels increased from a median of 0.5 mM (0.3, 0.8) to 2.1 mM (2.0, 2.3) (p = 0.02) post-shock. The baseline median hyaluronan levels increased significantly from 25 ng/mL (18, 86) to 168 ng/mL (86, 569), p = 0.05 but not the median vasopressor dependency index which increased within 1 h of resuscitation from zero to 0.39 mmHg-1 (0.06, 5.13), p = 0.065, and. Over the 48 h, there was a significant decrease in the systemic vascular resistance index (F = 7.46, p = 0.01) and increase in the pro-inflammatory cytokines [IL-6 (F = 8.90, p = 0.02), IL-8 (F = 5.28, p = 0.03), and VEGFA (F = 6.47, p = 0.02)].

CONCLUSIONS

This critically ill large-animal model was consistent in reproducing septic shock and will be applied in investigating advanced resuscitation and therapeutic interventions.

The impact of the COVID-19 pandemic on pediatric bloodstream infections and alteration in antimicrobial resistance phenotypes in Gram-positive bacteria, 2020-2022

BACKGROUND

Alteration in the etiology of pediatric bloodstream infections (BSIs) and antimicrobial resistance (AMR) is not well known during the Coronavirus disease 2019 (COVID-19) pandemic. This study aimed to investigate the impact of the COVID-19 pandemic on pediatric BSIs and alteration in antimicrobial resistance phenotypes in Gram-positive bacteria.

METHODS

The frequency of BSIs among children under 18 years old was retrospectively recorded in a tertiary children's hospital in Tehran, Iran from February 2020 to December 2022. The status of COVID-19 infection using reverse transcription polymerase chain reaction, bacteremia/fungemia according to BACTEC 9120 Culture System results, characterization of bacteria using biochemical tests, and antimicrobial susceptibility patterns for Gram-positive bacterial isolates using disk diffusion method were determined. Statistical analysis was done to measure the correlation of COVID-19 infection with BSIs and AMR.

RESULTS

Out of 13,345 COVID-19 tests and 4,194 BACTEC blood culture requests, bacteremia/fungemia were confirmed in 10.37% (435/4,194) of the patients who requested both tests simultaneously. The COVID-19 infection was confirmed in 25.3% (110/435) of the patients with bacteremia/fungemia. The infection with characterized Gram-positive bacteria (GPB) and fungi was detected in 32.3% (140/433) and 8.31% (36/433) of the cases, respectively. Coagulase-negative Staphylococcus (CNS, 72, 16.62%), S. aureus (36, 8.3%), and Enterococcus spp. (22, 5%) were among the common isolates. Candida spp. and non-Candida yeasts were detected in 6.7% and 13.4% of the cases, respectively. A positive correlation was shown between the CNS bacteremia and COVID-19 infection (p-value = 0.019). Antibiotic susceptibility testing results showed the highest frequency of resistance to azithromycin among CNS, azithromycin and tetracycline among S. aureus and tetracycline among Enterococcus spp. Methicillin-resistance phenotype in the S. aureus (MRSA) and coagulase-negative Staphylococcus spp. (MR-CNS) was detected in 40% and 61.5% of the strains, respectively and the Enterococci were resistant to vancomycin in 33.3% of the isolates.

CONCLUSION

A decline in the trend of BSIs by GPB and an increase in AMR was shown in children during the COVID-19 pandemic. Increasing antibiotic resistance is a concern; however, chloramphenicol, linezolid, and vancomycin remain active against common causes of GPB-BSIs.

Microbiological performance and adherence in blood culture protocols: The role of a second anaerobic bottle

Background

Bacteremia represents high rates of morbidity and mortality, especially in developing countries, highlighting the need for a diagnostic method that allows prompt and appropriate patient treatment. This study compared microbiological performance and adherence of two blood culture protocols for the diagnosis of bacteremia.

Methods

Quasi-experimental study conducted between June 2022 and February 2023. Two blood culture protocols were evaluated. Protocol 1 included two aerobic bottles and one anaerobic bottle. Protocol 2 included two aerobic and two anaerobic bottles. Protocols were analyzed in three phases: evaluation of protocol 1 (Phase 1); evaluation of protocol 1 plus educational activities for healthcare staff (Phase 2) and evaluation of protocol 2 (Phase 3).

Results

342 patients and 1155 blood culture bottles (732 aerobic and 423 anaerobic) were included. Positivity was 17.6 %, 22.8 % and 19.4 % in phases 1, 2 and 3, respectively. Among patients with bacteremia, 84.5 % had positive anaerobic bottles, with 9.9 % showing growth only in this bottle. The contamination rates were 1.9 %, 0.3 %, and 0.8 % for each phase, mainly in aerobic bottles. Median positivity time was 11 h for both bottes aerobic and anaerobic. Overall nursing adherence increased from 13.1 % in Phase 1, 25.9 % in Phase 2, and 28.1 % in Phase 3 (p = 0.009).

Conclusions

The findings indicate that adding a second anaerobic bottle does not enhance blood culture positivity. Rather than increasing bottle quantity, staff training might be a more effective approach to optimize results.

Antibiotic duration and route for treatment of adults with uncomplicated streptococcal bloodstream infections: a retrospective study in a large healthcare system

Data guiding the duration and route of streptococcal bloodstream infection (BSI) treatment are lacking. We conducted a retrospective cohort study of adults hospitalized with uncomplicated streptococcal BSI in a large integrated healthcare system from 2013 to 2020. The exposures of interest were antibiotic duration (5-10 days vs. 11-15 days) and antibiotic route (oral switch vs. entirely intravenous). The primary outcome was a composite 90-day outcome comprised of all-cause mortality, recurrent streptococcal BSI, or readmission. We performed non-inferiority analyses for each exposure. Separate multivariable Cox proportional hazards regression models were constructed for each exposure. The antibiotic duration analysis included 1,407 patients (5-10 days, n = 246; 11-15 days, n = 1,161). We found that 5-10-day courses were non-inferior to 11-15-day courses (P = 0.047). The antibiotic route analysis included 1,461 patients (oral switch, n = 1,112; entirely intravenous, n = 349). Oral step-down therapy did not meet the criteria for non-inferiority (P = 0.06). In the adjusted models, no significant difference was found in the primary outcome rate by antibiotic duration or antibiotic route at discharge. We found that 5-10-day courses were non-inferior to longer courses, and thus may be a safe and effective treatment option in the treatment of uncomplicated streptococcal bacteremia. Randomized controlled trials are needed to confirm the equivalent outcomes with shorter regimens and to definitively determine the optimal antibiotic route on discharge.

Changing epidemiology and antimicrobial resistance of bacteria causing bacteremia in Taiwan: 2002-2020

Bacteremia is associated with significant morbidity and mortality. The emergence of bacteria with antimicrobial resistance (AMR) has further exacerbated the poor outcomes associated with bacteremia. The Taiwan Surveillance of Antimicrobial Resistance (TSAR) program was established in 1998 to monitor bacterial epidemiology and antimicrobial resistance trends across all patient types and age groups. Between 2002 and 2020, a total of 14,539 non-duplicate bacteremia isolates were collected biennially from 29 hospitals during the months of July-September as part of the TSAR program. The three most common bacteremia agents were Escherichia coli (31%), Staphylococcus aureus (13.6%), and Klebsiella pneumoniae (12.7%) overall. However, there was a steady increase in the proportions of E. coli and Enterococcus faecium isolated from bacteremia cases (both P < 0.001), while the proportions of Acinetobacter spp. decreased. Regarding antimicrobial resistance, there was a notable increase in rates of third-generation cephalosporin and fluoroquinolone non-susceptibility among E. coli and K. pneumoniae, while the rates of carbapenem non-susceptibility were elevated but remained milder in these two species, especially in E. coli. Of concern is the alarming increase in vancomycin resistance among E. faecium, rising from 10.0% in 2004 to 47.7% in 2020. In contrast, the prevalence of methicillin-resistant S. aureus has remained stable at 51.2% overall. In conclusion, E. coli, with increasing third-generation cephalosporin and fluoroquinolone resistance, is the predominant cause of bacteremia in Taiwan during the 18-year surveillance. The escalating proportion of E. faecium in bacteremia, coupled with a concurrent upsurge in vancomycin resistance, presents a therapeutic challenge in the recent decade.

IMPORTANCE

AMR surveillance not only enables the identification of regional variations but also supports the development of coordinated efforts to combat AMR on a global scale. The TSAR has been a biennial, government-endorsed, multicenter study focusing on pathogens isolated from inpatients and outpatients in Taiwan hospitals since 1998. Our report presents an 18-year comprehensive analysis on blood isolates in the 2002-2020 TSAR program. The study highlights an alarming increase in the proportion of E. faecium causing bacteremia accompanied by elevated vancomycin resistance. It is worth noting that this trend differs from the observations in the United States and China. Understanding the composition of bacteria causing bacteremia, along with their prevalence of antimicrobial resistance, holds significant importance in establishing healthcare and research priorities. Additionally, this knowledge serves as a critical factor in evaluating the effectiveness of preventive interventions.

Impact of an antimicrobial stewardship program indicator on the appropriateness of the empiric antibiotic treatment of urinary source Escherichia coli bacteraemia

A prospective multicentre study was carried out between 2017 and 2021 to assess (1) the appropriateness of the empirical treatment to the local guidelines of urinary source Escherichia coli bacteraemia, (2) the appropriateness of empirical treatment to antibiotic sensitivity results and (3) the degree of error in the local guidelines regarding the antibiotic sensitivity reported in acute care hospitals enrolled in the vigilància de les infeccions relacionades amb l'atenció sanitària de Catalunya program. During the study period, 79.0% of the empirical treatments analysed complied with the guidelines and 88.1% were appropriate in view of the in vitro activity of the isolated strain. The rate of appropriateness rose from 73.8% in 2017 to 81.0% in 2021 (P < 0.001). The degree of error in the recommendations regarding the in vitro activity of the isolated strains was 5.9% and remained stable during the study period. Antibiotic families correctly prescribed according to the guidelines were third-generation cephalosporins (54.9%), carbapenems (16.8%) and combinations of penicillins and beta-lactamase inhibitors (16.4%). Of the 8009 E. coli strains, 19.0% were extended-spectrum beta-lactamases producers, 36.8% were resistant to quinolones and 0.5% were resistant to carbapenems. The broad implementation of an antimicrobial stewardship program with quality indicators of antibiotic use improved compliance to local guidelines in the empiric treatment of urinary tract E. coli bacteraemia. The degree of error in local guidelines was low but higher in more complex hospitals and in healthcare-associated infections. Guidelines need to be constantly updated with the use of epidemiological data, rapid diagnostic tests and the analysis of patient risk factors specific to each geographical area.

Examining the influence of Covid-19 restrictions, a nurse strike, and SARS-CoV-2 coinfection on bacteremia mortality: A Danish population-based cohort study (2019-2022)

Objectives

Bacteremia is an acute severe infection with high mortality. Changes in healthcare services and coinfections with SARS-CoV-2 may have affected the mortality for bacteremia during the COVID-19 pandemic, which has been reported for other major diseases. In this study we examine the all-cause bacteremia mortality amidst the COVID-19 pandemic.

Methods

A population-based cohort study comprised of laboratory confirmed bacteremia episodes in the Capital Region, Denmark (March 2019-February 2022). Cox proportional hazards models were used to calculate hazard ratios (HR) and 95 % confidence intervals (CI) for all-cause bacteremia mortality associated with the Covid-19 restriction period, a strike period, and coinfection with SARS-CoV-2, adjusted for possible confounders.

Results

A total of 14,912 bacteremia episodes were identified in 12,693 patients during the study period. The 30- and 90-day all-cause mortality were 19 % and 27 %, respectively. The fully adjusted HR for 30- and 90-day all-cause mortality associated with the Covid-19 restriction period were 0.91 (95 % CI, 0.84 to 0.99) and 0.90 (95 % CI, 0.84 to 0.96), respectively, compared to the remaining time period. The corresponding HRs associated with SARS-CoV-2 coinfection were 1.29 (95 % CI, 1.11 to 1.50) and 1.36 (95 % CI, 1.20 to 1.55) compared to patients without coinfection. The association between the national nurse strike and all-cause bacteremia mortality was inconclusive.

Conclusions

In this large population-based cohort study, a significant reduction in all-cause mortality for bacteremia was observed during the Covid-19 restriction period in Denmark, while coinfection with SARS-CoV-2 seem to be a substantial risk factor for all-cause bacteremia mortality.

A Multicenter Retrospective Study Evaluating Intravenous to Oral Antibiotic Stepdown for Uncomplicated Streptococcal Bacteremia

Background

The purpose of this study was to compare the efficacy and safety of intravenous (IV) versus oral (PO) stepdown therapy for uncomplicated streptococcal bacteremia.

Methods

This multicenter, retrospective study included adult patients with uncomplicated streptococcal bacteremia between 1 July 2019 and 1 July 2022. Patients who received IV therapy for the full treatment course were compared to patients who transitioned to PO therapy after initial IV therapy. The primary outcome was clinical success, defined as absence of infection recurrence, infection-related readmission, and infection-related mortality at 90 days. Secondary outcomes included microbiological success, length of stay (LOS), and IV line-associated complications.

Results

Of 238 patients included, 47.1% received PO stepdown therapy. Clinical success occurred in 94.4% and 94.6% in the IV only and PO stepdown groups, respectively (P = .946). Patients who transitioned to PO therapy received a median duration of IV therapy of 3.9 days (interquartile range, 2.9-7.3 days). Line complications were more frequent in the IV only group, primarily driven by catheter-related infections (7.2% vs 0%, P = .002). LOS was significantly shorter in the PO stepdown group (5.5 vs 9.2 days, P < .001).

Conclusions

Patients transitioned to PO antibiotics for uncomplicated streptococcal bacteremia had similar rates of clinical success compared to patients who received only IV therapy. With consideration of infectious source, severity of illness, and comorbidities, PO stepdown following initial IV antibiotics for uncomplicated streptococcal bacteremia in select patients is a reasonable approach that may result in decreased LOS and line-related complications.

adhesiomeR: a tool for Escherichia coli adhesin classification and analysis

Adhesins are crucial factors in the virulence of bacterial pathogens such as Escherichia coli. However, to date no resources have been dedicated to the detailed analysis of E. coli adhesins. Here, we provide adhesiomeR software that enables characterization of the complete adhesin repertoire, termed the adhesiome. AdhesiomeR incorporates the most comprehensive database of E. coli adhesins and facilitates an extensive analysis of adhesiome. We demonstrate that adhesiomeR achieves 98% accuracy when compared with experimental analyses. Based on analysis of 15,000 E. coli genomes, we define novel adhesiome profiles and clusters, providing a nomenclature for a unified comparison of E. coli adhesiomes.

Clinical and Bacteriological Specificities of Escherichia coli Bloodstream Infections From Biliary Portal of Entries

BACKGROUND

Escherichia coli is frequently responsible for bloodstream infections (BSIs). Among digestive BSIs, biliary infections appear to be less severe. Respective roles of host factors, bacterial determinants (phylogroups, virulence, and antibiotic resistance), and portal of entry on outcome are unknown.

METHODS

Clinical characteristics and prognosis of 770 episodes of E coli BSI were analyzed and isolates sequenced (Illumina technology) comparing phylogroups, multilocus sequence type, virulence, and resistance gene content. BSI isolates were compared with 362 commensal E coli from healthy subjects.

RESULTS

Among 770 episodes, 135 were biliary, 156 nonbiliary digestive, and 479 urinary. Compared to urinary infections, BSIs of digestive origin occurred significantly more in men, comorbid, and immunocompromised patients. Digestive portal of entry was significantly associated with septic shock and death. Among digestive infections, patients with biliary infections were less likely to die (P = .032), despite comparable initial severity. Biliary E coli resembled commensals (phylogroup distribution, sequence type, and few virulence-associated genes) whereas nonbiliary digestive and urinary strains carried many virulence-associated genes.

CONCLUSIONS

Escherichia coli strains responsible for biliary infections exhibit commensal characteristics and are associated with lower mortality rates, despite similar initial severity, than other digestive BSIs. Biliary drainage in addition to antibiotics in the management of biliary infections may explain improved outcome.

Comparing the Prognostic Impacts of Delayed Administration of Appropriate Antimicrobials in Older Patients with Afebrile and Febrile Community-Onset Bacteremia

Although prompt administration of an appropriate antimicrobial therapy (AAT) is crucial for reducing mortality in the general population with community-onset bacteremia, the prognostic effects of delayed AAT in older individuals with febrile and afebrile bacteremia remain unclear. A stepwise and backward logistic regression analysis was used to identify independent predictors of 30-day mortality. In a 7-year multicenter cohort study involving 3424 older patients (≥65 years) with community-onset bacteremia, febrile bacteremia accounted for 27.1% (912 patients). A crucial association of afebrile bacteremia and 30-day mortality (adjusted hazard ratio [AHR], 1.69; p < 0.001) was revealed using Cox regression and Kaplan-Meier curves after adjusting for the independent predictors of mortality. Moreover, each hour of delayed AAT was associated with an average increase of 0.3% (adjusted odds ratio [AOR], 1.003; p < 0.001) and 0.2% (AOR, 1.002; p < 0.001) in the 30-day crude mortality rates among patients with afebrile and febrile bacteremia, respectively, after adjusting for the independent predictors of mortality. Similarly, further analysis based on Cox regression and Kaplan-Meier curves revealed that inappropriate empirical therapy (i.e., delayed AAT administration > 24 h) had a significant prognostic impact, with AHRs of 1.83 (p < 0.001) and 1.76 (p < 0.001) in afebrile and febrile patients, respectively, after adjusting for the independent predictors of mortality. In conclusion, among older individuals with community-onset bacteremia, the dissimilarity of the prognostic impacts of delayed AAT between afebrile and febrile presentation was evident.

Comparative epidemiology of bacteraemia in two ageing populations: Singapore and Denmark

Burden of bacteraemia is rising due to increased average life expectancy in developed countries. This study aimed to compare the epidemiology and outcomes of bacteraemia in two similarly ageing populations with different ethnicities in Singapore and Denmark. Historical cohorts from the second largest acute-care hospital in Singapore and in the hospitals of two Danish regions included patients aged 15 and above who were admitted from 1 January 2006 to 31 December 2016 with at least 1 day of hospital stay and a pathogenic organism identified. Among 13 144 and 39 073 bacteraemia patients from Singapore and Denmark, similar 30-day mortality rates (16.5%; 20.3%), length of hospital stay (median 14 (IQR: 9-28) days; 11 (6-21)), and admission rate to ICU (15.5%; 15.6%) were observed, respectively. Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus ranked among the top four in both countries. However, Singaporeans had a higher proportion of patients with diabetes (46.8%) and renal disease (29.5%) than the Danes (28.0% and 13.7%, respectively), whilst the Danes had a higher proportion of patients with chronic pulmonary disease (18.0%) and malignancy (35.3%) than Singaporeans (9.7% and 16.2%, respectively). Our study showed that top four causative organisms and clinical outcomes were similar between the two cohorts despite pre-existing comorbidities differed.

Accurate and rapid antibiotic susceptibility testing using a machine learning-assisted nanomotion technology platform

Antimicrobial resistance (AMR) is a major public health threat, reducing treatment options for infected patients. AMR is promoted by a lack of access to rapid antibiotic susceptibility tests (ASTs). Accelerated ASTs can identify effective antibiotics for treatment in a timely and informed manner. We describe a rapid growth-independent phenotypic AST that uses a nanomotion technology platform to measure bacterial vibrations. Machine learning techniques are applied to analyze a large dataset encompassing 2762 individual nanomotion recordings from 1180 spiked positive blood culture samples covering 364 Escherichia coli and Klebsiella pneumoniae isolates exposed to cephalosporins and fluoroquinolones. The training performances of the different classification models achieve between 90.5 and 100% accuracy. Independent testing of the AST on 223 strains, including in clinical setting, correctly predict susceptibility and resistance with accuracies between 89.5% and 98.9%. The study shows the potential of this nanomotion platform for future bacterial phenotype delineation.

Clinical significance of inflammatory markers for evaluating disease severity of mixed-pathogen bloodstream infections of both Enterococcus spp. and Candida spp

Objective

In recent decades, there has been a notable increase in the morbidity and mortality rates linked to bacteremia and candidemia. This study aimed to investigate the clinical significance of inflammatory markers in assessing the disease severity in critically ill patients suffering from mixed-bloodstream infections (BSIs) due to Enterococcus spp. and Candida spp.

Methods

In this retrospective research, patients diagnosed with BSIs who were admitted to the intensive care unit (ICU) during the period of January 2019 to December 2022 were analyzed. The patients were divided into two groups: a mixed-pathogen BSI group with both Enterococcus spp. and Candida spp., and a single-pathogen BSI group with only Enterococcus spp. The study examined the differences in inflammatory marker levels and disease severity, including Acute Physiology and Chronic Health Evaluation (APACHE) II scores, duration of ICU stay, and 30-day mortality, between the two groups. Furthermore, we sought to scrutinize the potential associations among these aforementioned parameters.

Results

The neutrophil-to-lymphocyte ratios (NLRs) and levels of plasma C-reactive protein (CRP), interleukin (IL)-6, IL-8, and tumor necrosis factor-α (TNF-α) in the mixed-pathogen BSI group were higher than those in the single-pathogen BSI group. Spearman's rank correlation analysis showed that NLRs and plasma CRP and IL-6 levels were positively correlated with disease severity in the mixed-pathogen BSI group. Further, the levels of plasma IL-8 and TNF-α were also positively correlated with ICU stay duration and 30-day mortality. In multivariate analysis, plasma CRP and IL-6 levels were independently associated with 30-day mortality.

Conclusion

Mixed-pathogen BSIs caused by Enterococcus spp. and Candida spp. may give rise to increased NLRs and plasma CRP, IL-6, IL-8, and TNF-α levels in comparison to BSI caused by Enterococcus spp. only, thus leading to elevated disease severity in critically ill patients.

Population-based genomic surveillance of Pseudomonas aeruginosa causing bloodstream infections in a large Canadian health region

PURPOSE

Population-based surveillance was undertaken to determine clinical factors, susceptibility patterns, and incidence rates (IR) of Pseudomonas aeruginosa causing bloodstream infections (BSIs) in a Canadian region (2010-2018).

METHODS

We combined clinical data with genomics to characterize P. aeruginosa (BSIs) (n = 167) in a well-defined Canadian (Calgary) human population over a 9-year period (2010-2018).

RESULTS

The annual population IR per 100,000 patient years increased from 3.4/100,000 in 2010 to 5.9/100,000 in 2018, with the highest IRs in elderly males from the hospital setting. Over a quarter of patients presented with febrile neutropenia, followed by urinary tract infections and pneumonia. Antimicrobial resistance (AMR) rates and determinants were rare. The P. aeruginosa population was polyclonal consisting of three dominant sequence types (STs), namely ST244, ST111, and ST17. Antimicrobial-susceptible ST244 was the most common clone and belonged to three clades (A, B, C). The ST244 IR/100,000 increased over time due to the expansion of clade C. Multidrug-resistant ST111 was the second most common clone and IR/100,000 decreased over time. ST111 belonged to three clades (A, B, C) with clade C containing blaVIM-2. Different serotypes were linked to various STs. The IR/100,000 of P. aeruginosa that belonged to serotypes O6 increased significantly over time.

CONCLUSION

An effective multivalent vaccine consisting of five serotypes (O1, O3, O5, O6, O11) would confer protection to > 70% of Calgary residents with P. aeruginosa BSIs. This study has provided a unique perspective of the population dynamics over time of P. aeruginosa STs, clades, and serotypes responsible for BSIs.

A convergent evolutionary pathway attenuating cellulose production drives enhanced virulence of some bacteria

Bacteria adapt to selective pressure in their immediate environment in multiple ways. One mechanism involves the acquisition of independent mutations that disable or modify a key pathway, providing a signature of adaptation via convergent evolution. Extra-intestinal pathogenic Escherichia coli (ExPEC) belonging to sequence type 95 (ST95) represent a global clone frequently associated with severe human infections including acute pyelonephritis, sepsis, and neonatal meningitis. Here, we analysed a publicly available dataset of 613 ST95 genomes and identified a series of loss-of-function mutations that disrupt cellulose production or its modification in 55.3% of strains. We show the inability to produce cellulose significantly enhances ST95 invasive infection in a rat model of neonatal meningitis, leading to the disruption of intestinal barrier integrity in newborn pups and enhanced dissemination to the liver, spleen and brain. Consistent with these observations, disruption of cellulose production in ST95 augmented innate immune signalling and tissue neutrophil infiltration in a mouse model of urinary tract infection. Mutations that disrupt cellulose production were also identified in other virulent ExPEC STs, Shigella and Salmonella, suggesting a correlative association with many Enterobacteriaceae that cause severe human infection. Together, our findings provide an explanation for the emergence of hypervirulent Enterobacteriaceae clones.

Rapid Visual Detection of Methicillin-Resistant Staphylococcus aureus in Human Clinical Samples via Closed LAMP Assay Targeting mecA and spa Genes

The emergence of antimicrobial resistance (AMR), particularly methicillin-resistant Staphylococcus aureus (MRSA), poses a significant global health threat as these bacteria increasingly become resistant to the most available therapeutic options. Thus, developing an efficient approach to rapidly screen MRSA directly from clinical specimens has become vital. In this study, we establish a closed-tube loop-mediated isothermal amplification (LAMP) method incorporating hydroxy-naphthol blue (HNB) colorimetric dye assay to directly detect MRSA from clinical samples based on the presence of mecA and spa genes. In total, 125 preidentified S. aureus isolates and 93 clinical samples containing S. aureus were sourced from the microbiology laboratory at Hamad General Hospital (HGH). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were computed based on conventional PCR. The assay demonstrated 100% specificity, 91.23% sensitivity, 0.90 Cohen Kappa (CK), 100% PPV, and 87.8% NPV for the clinical samples, while clinical isolates exhibited 100% specificity, 97% sensitivity, 0.926 CK, 100% PPV, and 88.89% NPV. Compared to cefoxitin disk diffusion, LAMP provided 100% specificity and sensitivity, 1.00 CK, and 100% for PPV and NPV. The study revealed that the closed-tube LAMP incorporating (HNB) dye is a rapid technique with a turnaround time of less than 1 h and high specificity and sensitivity.

In silico Evaluation of a Vancomycin Dosing Guideline Among Adults with Serious Infections

BACKGROUND

This study aimed to compare the achievement of pharmacokinetic-pharmacodynamic (PK-PD) exposure targets for vancomycin using a newly developed dosing guideline with product-information-based dosing in the treatment of adult patients with serious infections.

METHODS

In silico product-information- and guideline-based dosing simulations for vancomycin were performed across a range of doses and patient characteristics, including body weight, age, and renal function at 36-48 and 96 hours, using a pharmacokinetic model derived from a seriously ill patient population. The median simulated concentration and area under the 24-hour concentration-time curve (AUC 0-24 ) were used to measure predefined therapeutic, subtherapeutic, and toxicity PK-PD targets.

RESULTS

Ninety-six dosing simulations were performed. The pooled median trough concentration target with guideline-based dosing at 36 and 96 hours was achieved in 27.1% (13/48) and 8.3% (7/48) of simulations, respectively. The pooled median AUC 0-24 /minimum inhibitory concentration ratio with guideline-based dosing at 48 and 96 hours was attained in 39.6% (19/48) and 27.1% (13/48) of simulations, respectively. Guideline-based dosing simulations yielded improved trough target attainment compared with product-information-based dosing at 36 hours and significantly less subtherapeutic drug exposure. The toxicity threshold was exceeded in 52.1% (25/48) and 0% (0/48) for guideline- and product-information-information-based dosing, respectively ( P < 0.001).

CONCLUSIONS

A Critical care vancomycin dosing guideline appeared slightly more effective than standard dosing, as per product information, in achieving PK-PD exposure associated with an increased likelihood of effectiveness. In addition, this guideline significantly reduced the risk of subtherapeutic exposure. The risk of exceeding toxicity thresholds, however, was greater with the guideline, and further investigation is suggested to improve dosing accuracy and sensitivity.

Risk of Staphylococcus aureus Bacteremia Before and After Solid Organ Transplantation

BACKGROUND

Solid organ transplant recipients are at high risk for Staphylococcus aureus bacteremia, but the risks before and after transplantation require further research.

METHODS

We performed a population-based retrospective self-controlled study using the State Inpatient Database from 10 states in the United States. Adult and pediatric patients who had solid organ transplantation from 2004 to 2018 were tracked longitudinally for 1 y before and after transplantation outside of the immediate peritransplant periods. The exposure of interest was solid organ transplantation, and the outcome of interest was hospitalization with S. aureus bacteremia.

RESULTS

Of 75 549 patients, 581 (0.77%) and 239 (0.32%) were hospitalized with S. aureus bacteremia in the pretransplant and posttransplant periods, respectively ( P < 0.001). Overall, the odds of hospitalization with S. aureus bacteremia increased from 7 to 12 mo to 1 to 6 mo before transplantation (odds ratio, 1.24; 95% confidence interval, 1.05-1.46) and then decreased following transplantation (odds ratio, 0.35; 95% confidence interval, 0.28-0.45; 7-12 mo after transplantation). The decreased rate after transplantation was driven by the cases associated with central line-associated bloodstream infections and endocarditis among kidney and heart transplant recipients. Odds of hospitalization with S. aureus bacteremia did not change after liver transplantation, whereas they increased after lung transplantation.

CONCLUSIONS

In addition to immunosuppression, the reversal of organ failure and associated requirements for organ support following transplantation may play an important role in the risk of S. aureus bacteremia in solid organ transplant recipients. These results can guide infection prevention approaches and future research on S. aureus infections in transplant patients.

Importance of Blood Glucose Management Before 18F-FDG PET/CT in 322 Patients with Bacteremia of Unknown Origin

We investigated the effects of blood glucose levels on the performance of ¹⁸F-FDG PET/CT for detecting an infection focus in patients with bacteremia. Methods: A total of 322 consecutive patients with bacteremia who underwent ¹⁸F-FDG PET/CT between 2010 and 2021 were included. Logistic regression analysis was performed to evaluate the association between finding a true-positive infection focus on ¹⁸F-FDG PET/CT and blood glucose level, type of diabetes, and use of hypoglycemic medication. C-reactive protein, leukocyte count, duration of antibiotic treatment, and type of isolated bacteria were considered as well. Results: Blood glucose level (odds ratio, 0.76 per unit increase; P = <0.001) was significantly and independently associated with ¹⁸F-FDG PET/CT outcome. In patients with a blood glucose level between 3.0 and 7.9 mmol/L (54-142 mg/dL), the true-positive detection rate of ¹⁸F-FDG PET/CT varied between 61% and 65%, whereas in patients with a blood glucose level between 8.0 and 10.9 mmol/L (144-196 mg/dL), the true-positive detection rate decreased to 30%-38%. In patients with a blood glucose level greater than 11.0 mmol/L (200 mg/dL), the true-positive detection rate was 17%. In addition to C-reactive protein (odds ratio, 1.004 per point increase; P = 0.009), no other variables were independently associated with ¹⁸F-FDG PET/CT outcome. Conclusion: In patients with moderate to severe hyperglycemia, ¹⁸F-FDG PET/CT was much less likely to identify the focus of infection than in normoglycemic patients. Although current guidelines recommend postponing ¹⁸F-FDG PET/CT only in cases of severe hyperglycemia with glucose levels greater than 11 mmol/L (200 mg/dL), a lower blood glucose threshold seems to be more appropriate in patients with bacteremia of unknown origin and other infectious diseases.

Pediatric Swine Model of Methicillin-Resistant Staphylococcus aureus Sepsis-Induced Coagulopathy, Disseminated Microvascular Thrombosis, and Organ Injuries

Sepsis-induced coagulopathy leading to disseminated microvascular thrombosis is associated with high mortality and has no existing therapy. Despite the high prevalence of Gram-positive bacterial sepsis, especially methicillin-resistant Staphylococcus aureus (MRSA), there is a paucity of published Gram-positive pediatric sepsis models. Large animal models replicating sepsis-induced coagulopathy are needed to test new therapeutics before human clinical trials.

HYPOTHESIS

Our objective is to develop a pediatric sepsis-induced coagulopathy swine model that last 70 hours.

METHODS AND MODELS

Ten 3 weeks old piglets, implanted with telemetry devices for continuous hemodynamic monitoring, were IV injected with MRSA (n = 6) (USA300, Texas Children's Hospital 1516 strain) at 1 × 109 colony forming units/kg or saline (n = 4). Fluid resuscitation was given for heart rate greater than 50% or mean arterial blood pressure less than 30% from baseline. Acetaminophen and dextrose were provided as indicated. Point-of-care complete blood count, prothrombin time (PT), activated thromboplastin time, d-dimer, fibrinogen, and specialized coagulation assays were performed at pre- and post-injection, at 0, 24, 48, 60, and 70 hours. Piglets were euthanized and necropsies performed.

RESULTS

Compared with the saline treated piglets (control), the septic piglets within 24 hours had significantly lower neurologic and respiratory scores. Over time, PT, d-dimer, and fibrinogen increased, while platelet counts and activities of factors V, VII, protein C, antithrombin, and a disintegrin and metalloproteinase with thrombospondin-1 motifs (13th member of the family) (ADAMTS-13) decreased significantly in septic piglets compared with control. Histopathologic examination showed minor focal organ injuries including microvascular thrombi and necrosis in the kidney and liver of septic piglets.

INTERPRETATIONS AND CONCLUSIONS

We established a 70-hour swine model of MRSA sepsis-induced coagulopathy with signs of consumptive coagulopathy, disseminated microvascular thrombosis, and early organ injuries with histological minor focal organ injuries. This model is clinically relevant to pediatric sepsis and can be used to study dysregulated host immune response and coagulopathy to infection, identify potential early biomarkers, and to test new therapeutics.

Synthesis and biological evaluation of ruthenium complexes containing phenylseleny against Gram-positive bacterial infection by damage membrane integrity and avoid drug-resistance

Compounds modified with selenium atom as potential antibacterial agents have been exploited to combat the nondrug-resistant bacterial infection. In this study, we designed and synthesized four ruthenium complexes retouching of selenium-ether. Fortunately, those four ruthenium complexes shown excellent antibacterial bioactive (MIC: 1.56-6.25 μg/mL) against Staphylococcus aureus (S. aureus), and the most active complex Ru(II)-4 could kill S. aureus by targeting the membrane integrity and avoid the bacteria to evolve drug resistance. Moreover, Ru(II)-4 was found to significantly inhibit the formation of biofilms and biofilm eradicate capacity. In toxicity experiments, Ru(II)-4 exhibited poor hemolysis and low mammalian toxicity. To illustrate the antibacterial mechanism: we conducted scanning electron microscope (SEM), fluorescent staining, membrane rupture and DNA leakage assays. Those results demonstrated that Ru(II)-4 could destroy the integrity of bacterial cell membrane. Furthermore, both G. mellonella wax worms infection model and mouse skin infection model were established to evaluate the antibacterial activity of Ru(II)-4 in vivo, the results indicated that Ru(II)-4 was a potential candidate for combating S. aureus infections, and almost non-toxic to mouse tissue. Thus, all the results indicated that introducing selenium-atom into ruthenium compounds were a promising strategy for developing interesting antibacterial agents.

MRSA screening: incidence and maternal postpartum outcomes in an obstetric population at a tertiary care center

PURPOSE

To assess the incidence of MRSA positive patients in pregnancy, as well as the postpartum outcomes in MRSA positive patients.

METHODS

This is a retrospective cohort study of women who underwent universal MRSA universal at a tertiary medical center. A MRSA swab was routinely collected as part of the patient's prenatal care at 35-37 weeks gestation or on admission to labor and delivery. Demographic information and decolonization antibiotics were collected by electronic medical record review, using ICD-9 codes. Outcome data were collected, including mode of delivery, hospital length of stay, endometritis, wound cellulitis, and wound infection. p < 0.05 was considered significant. A univariate logistic regression and a multivariable binary logistic regression model were used to analyze the strength of association between outcomes and MRSA status. Statistical analysis was performed with SAS, version 9.4.

RESULTS

The incidence of MRSA during the 4 year study period was 1.9% (82 MRSA positive out of 4369 total patients). 90.2% (74/82) of MRSA positive patients received decolonization antibiotics. No difference was noted in mode of delivery. Logistic regression failed to identify any significant differences in other relevant outcomes for MRSA positive women including endometritis 1.1 (0.1-17.5) [positive 0, versus negative 0.6% (n = 24)], wound cellulitis 5.9 (0.4-82.1) positive 0, versus negative 0.1% (Gorwitz et al. in J Infect Dis 197:1226-1234, 2008) and wound infection 3.3 (0.6-16.9) [positive 1.2%, versus negative 0.5% ( in Am J Infect Control 32:470-85, 2004)] when compared to MRSA negative women.

CONCLUSION

When universal MRSA screening was performed at an academic tertiary care center, the overall incidence of MRSA was low. MRSA positive and subsequently decolinzed patients did not have any identified increase in postpartum infectious morbidity, as compared to MRSA negative patients.

Integrative omics identifies conserved and pathogen-specific responses of sepsis-causing bacteria

Even in the setting of optimal resuscitation in high-income countries severe sepsis and septic shock have a mortality of 20-40%, with antibiotic resistance dramatically increasing this mortality risk. To develop a reference dataset enabling the identification of common bacterial targets for therapeutic intervention, we applied a standardized genomic, transcriptomic, proteomic and metabolomic technological framework to multiple clinical isolates of four sepsis-causing pathogens: Escherichia coli, Klebsiella pneumoniae species complex, Staphylococcus aureus and Streptococcus pyogenes. Exposure to human serum generated a sepsis molecular signature containing global increases in fatty acid and lipid biosynthesis and metabolism, consistent with cell envelope remodelling and nutrient adaptation for osmoprotection. In addition, acquisition of cholesterol was identified across the bacterial species. This detailed reference dataset has been established as an open resource to support discovery and translational research.

Risk of Bloodstream Infection in Patients with Systemic Lupus Erythematosus Exposed to Prolonged Medium-to-High-Dose Glucocorticoids

OBJECTIVES

This study aimed to investigate the incidence rate and risk factors of bloodstream infection (BSI) in patients with systemic lupus erythematosus (SLE) exposed to medium to high doses of glucocorticoids.

METHODS

This study included 1109 treatment episodes with prolonged (≥4 weeks) medium-to-high-dose glucocorticoids (≥15 mg/day prednisolone) in 612 patients with SLE for over 14 years. Clinical features regarding systemic lupus erythematosus disease activity index 2000 (SLEDAI-2K), immunosuppressant use, and laboratory results were obtained from the electronic medical database. The primary outcome of this study was the 1-year incidence of BSI. The effect of clinical factors on the outcome was investigated using a generalized estimating equation.

RESULTS

During a total of 1078.64 person-years, 30 cases of BSI occurred, with an incidence rate of 2.78 (95% confidence interval (CI) 1.88-3.97) per 100 person-years. Mortality rate of the treatment episodes with BSI was 16.7%, which was significantly higher than that in the other episodes (incidence rate ratio (IRR) 19.59, 95% CI 7.33-52.44). When the incidence rate of BSI was stratified by baseline glucocorticoid dose and SLEDAI-2K score, a higher incidence rate of BSI occurred as disease activity or baseline glucocorticoid dose increased. In the multivariable analysis, SLEDAI-2K ≥20 (adjusted IRR (aIRR) 4.66, 95% CI 2.17-10.00), initial baseline prednisolone ≥ 60 mg/day (aIRR 2.42, 95% CI 1.11-5.32), and cumulative prednisolone dose ≥15 mg/day during the previous 6 months (aIRR 2.13, 95% CI 1.03-4.40) significantly increased the risk of BSI.

CONCLUSION

In patients with SLE exposed to prolonged medium-to-high-dose glucocorticoids, the 1-year incidence rate of BSI was significantly higher than previously reported in the general patients with SLE. Severe disease activity, and high-dose glucocorticoid treatment previously or at baseline increased the risk of BSI.

Oral stepdown in Gram-positive bloodstream infections: A step in the right direction

Bloodstream infections (BSIs) due to Gram-positive organisms have traditionally been treated with prolonged courses of intravenous antimicrobials. However, this dogma is associated with substantial burden to the patient and health care system. Consequently, there is growing interest in the utilization of oral stepdown therapy, defined as the transition of intravenous therapy to an active oral agent, for this indication. This review highlights available literature examining oral stepdown in adult patients with BSI due to commonly encountered Gram-positive pathogens, including Staphylococcus aureus, Streptococcus spp., and Enterococcus spp. Support for oral stepdown in this setting is primarily derived from observational studies subject to selection bias. Nevertheless, this treatment strategy exhibits promising potential in carefully selected patients as it is consistently associated with reductions in hospital length of stay without jeopardizing clinical cure or survivability. Prospective, randomized trials are needed for validation of oral stepdown in Gram-positive BSI and to identify the optimal patient population and regimen.

Antimicrobial resistance prevalence of Escherichia coli and Staphylococcus aureus amongst bacteremic patients in Africa: a systematic review

OBJECTIVES

Antimicrobial resistance (AMR) is a global concern among infectious diseases. Bloodstream infections can potentially become life-threatening if they become untreatable with conventional antimicrobials. This review aims to provide an understanding of the AMR prevalence and trends of common bacteremic pathogens, namely Escherichia coli and Staphylococcus aureus in the World Health Organization (WHO) Africa region.

METHODS

PubMed and Google Scholar were searched using relevant keywords for published human studies (excluding case reports and reviews) reporting bacteremic AMR data on the pathogens of interest between 2008 and 2019. Two reviewers independently screened the articles against a pre-defined eligibility criterion. Data extraction and analysis were achieved with different platforms: Covidence, Excel, R version 3.6.3, and QGIS v3.4.5. The pooled prevalence, 95% confidence intervals, and I² index (a measure of heterogeneity) were calculated for the various pathogen-antibiotic combinations.

RESULTS

Five hundred sixty-two papers were retrieved, with 27 papers included in the final analysis. Only 23.4% (11/47) of member states of the WHO African region had reports on AMR in bacteremia. The Clinical and Laboratory Standards Institute (CLSI) (78.5%) was the most common standard used in the region. For E. coli, the pooled resistance was: cefotaxime (42%), imipenem (4%), meropenem (0%), and colistin (0%). For S. aureus, the calculated pooled resistance was cloxacillin (34%), oxacillin (12%), and vancomycin (0%). There was a high degree of variation across studies (I² > 90%).

CONCLUSION

The pooled resistance rates indicate a concerning degree of methicillin-resistant and Extended Spectrum-ß-lactamase-producing pathogens. The paucity of AMR data also presents challenges for a comprehensive understanding of the situation in the region. Continent-wide and standardized surveillance efforts therefore need strengthening.

Differences in the distribution of pathogens and antimicrobial resistance in bloodstream infections in migrants compared with non-migrants in Denmark

BACKGROUND

We wish to study disparities in bloodstream infections in migrants and non-migrants by comparing the distribution of pathogens and their resistance patterns in long-term migrants with that in non-migrants in Denmark.

METHODS

The study is based on a cohort of migrants, who received residency in Denmark between 1993 and 2015 and a control group of non-migrants. The cohort was linked to a database of bloodstream infections from 2000 to 2015 covering two regions in Denmark. First-time bloodstream infections in individuals ≥18 years of age at the time of sampling were included. We calculated odds ratios adjusted for age, sex, year of sampling, comorbidity, and place of acquisition (hospital- or community-acquired).

RESULTS

We identified 4,703 bloodstream infection cases. Family-reunified migrants and refugees had higher odds of Escherichia coli than non-migrants (OR 1.89 95%CI: 1.46-2.44 and OR 1.55 95%CI: 1.25-1.92) and lower odds of Streptococcus pneumoniae (OR 0.38 95%CI: 0.21-0.67 and OR 0.52 95%CI: 0.34-0.81). Differences in pathogen distribution were only prevalent in community-acquired bloodstream infections. Refugees had higher odds of Escherichia coli resistant to piperacillin-tazobactam, ciprofloxacin, and gentamicin compared with non-migrants. Family-reunified migrants had higher odds of Escherichia coli and other Enterobacterales resistant to ciprofloxacin.

CONCLUSIONS

Migrants had a higher proportion of community-acquired bloodstream infections with Escherichia coli as well as higher odds of bloodstream infections with resistant Escherichia coli compared with non-migrants. These novel results are relevant for improving migrant health by focussing on preventing and treating infections especially with Escherichia coli such as urinary tract and abdominal infections.

Evaluation of Clinical Approach and Outcomes Staphylococcus aureus Bacteremia

Objective

Despite appropriate treatment and early diagnosis methods, Staphylococcus aureus bacteremia (SAB) is still associated with a high mortality rate. This study aims to evaluate the clinical features and approaches to SAB and to analyze the parameters that may affect 7-day and 30-day mortality.

Materials and Methods

Adult patients with SAB data between 2011 and 2018 were evaluated retrospectively. Clinical data, patient demographics, and 7-day and 30-day mortality rates were obtained from their medical records.

Results

In total, 144 patients were included in the study; 57.6% (83/144) of patients were men, and the mean age was 65.2±16.5 years. The most common source of infection was the central-line catheter (38.9%), followed by intra-abdominal (21%), respiratory (16.7), infective endocarditis (5.6%), and osteoarticular foci (2.1%). Fifteen percent (15%) of the strains were methicillin resistant. Transthoracic echocardiography (TTE) was performed for 80.6% (116/144) patients. Infectious diseases specialist consultation within 96 hours from blood culture signal was requested in 79.9%. Overall, 7-day mortality was 11.8%, and 30-day mortality was 21.5%. Staying in intensive care units (ICU) increased the risk of 30-day mortality by 1.1 times, and respiratory-focused SAB increased the risk by 4.3 times.

Conclusion

SAB is still a big threat. Staphylococcal pneumonia remains a severe infection. Several prognostic factors influence mortality. Identifying the source, ensuring source control, and appropriate initial therapy as soon as possible are critical for reducing mortality and morbidity in SAB.

Optimal Use and Need for Therapeutic Drug Monitoring of Teicoplanin in Children: A Systematic Review

BACKGROUND

Teicoplanin is a glycopeptide antimicrobial that treats serious invasive infections caused by gram-positive bacteria, such as the methicillin-resistant Staphylococcus aureus. Despite some comparable advantages, there is no guideline or clinical recommendation for teicoplanin in the pediatric population, unlike vancomycin where abundant studies and the recently revised guideline on therapeutic drug level monitoring (TDM) exist.

METHODS

The systematic review was performed in accordance with the preferred reporting items for systematic reviews. Two authors (JSC and SHY) searched PubMed, Embase, and Cochrane Library databases using relevant terms independently.

RESULTS

Fourteen studies were finally included with a total of 1,380 patients. TDM was available in 2,739 samples collected in the nine studies. Dosing regimens varied widely, and eight studies used recommended dosing regimens. Timing for measuring TDM was mostly 72-96 hours or longer after the initiation of the first dose, which was expected to be a steady-state. The majority of studies had target trough levels of 10 µg/mL or above. Three studies reported that the clinical efficacy and treatment success rate of teicoplanin was 71.4%, 87.5%, and 88%. Adverse events associated with teicoplanin use were described in six studies with a focus on renal and/or hepatic impairment. Except for one study, no significant relation was noted between the incidence of adverse events and trough concentration.

CONCLUSION

Current evidence on teicoplanin trough levels in pediatric populations is insufficient due to heterogeneity. However, target trough levels with favorable clinical efficacy are achievable by recommended dosing regimen in the majority of patients.

The factors associated with the trend in incidence of Bacteraemia and associated mortality over 30 years

BACKGROUND

Studies have reported increased incidence of BSI over the past decades and indicate that it is necessary to investigate the causes. The aim of this study was to determine the factors affecting trends in the incidence of bacteraemias and associated mortality.

METHODS

We conducted a retrospective cohort study assessing prospectively collected data of all clinically significant bacteraemias between 1991 and 2020 in a 450-bed hospital. We determined the evolution of bacteraemia-associated incidence, adjusted 30-day mortality and performed multivariable logistic regression to compare the evolution of variables associated with mortality between 5-year periods.

RESULTS

6777 episodes were included, 59.7% males, age 66.5 ± 18.2, 39.4% ≥ 75 years. The incidence total increased: 43.8/100,000/year in 1991-1995 to 205 in 2016-2020; community-acquired bacteraemia (24.9 to 139) and hospital-acquired (0.36/1000 inpatients-days to 1.09). Bacteraemia with source in vascular catheter, urinary and biliary tract increased. The 30-day mortality rate of patients was 1179/6777 (17.4%) in the whole series and population-adjusted mortality incidence increased from 11.4/100,000 in 1991-1996 to 28.4 in 2016-2020 (RR 2.49, 95% CI 2.01-3.08). Mortality was higher in men (18.2% vs 16.3%) and those over 74 years (22.2% vs 14.3%). Appropriate empirical antimicrobial treatment improved (66.5% to 73.1%), 30-day mortality of patients decreased from 26.1 to 13.9%. When comparing the evolution of the factors associated with mortality between 1991 and 1996 vs 2016-2020, the frequency of some variables associated with higher mortality increased: male sex (OR 1.38, 95% CI 1.10-1,74), age (OR 1.02, 1.01-10.3), immunosuppressive treatment (OR 3.1, 2.09-4.6), polymicrobial bacteraemia (OR 1.76, 1.12-2.79), and others decreased: severe sepsis/septic shock (OR 0.70, 0.52-0.93), spontaneous bacterial peritonitis in cirrhosis (OR 0.06, 0.02-0.23), endocarditis (OR 0.54, 0.35-0.83); on the other hand, the frequency of factors associated with lower mortality increased: urinary (OR 1.67, 95% CI 1.23-2.27) and bile tract source (OR 1.59, 1.04-2.43), and adequate empirical treatment (OR 1.42, 95% CI 1.10-1.83).

CONCLUSIONS

The incidence of bacteraemia increased due to more elderly, co-morbid patients undergoing procedures and more device related bacteraemia. The percentage of mortality decreased because adequate empirical treatment improved, decreased spontaneous bacterial peritonitis in cirrhosis and endocarditis, and increased bacteraemia of urinary and biliary tract source.

Increase in methicillin-susceptible Staphylococcus aureus bloodstream infections in Switzerland: a nationwide surveillance study (2008-2021)

PURPOSE

An increasing burden of Staphylococcus aureus bloodstream infections (BSI), despite a decrease in the percentage of methicillin-resistant S. aureus (MRSA), was described recently in other European countries. The main aim of this study was to analyse recent temporal trends of S. aureus, methicillin-susceptible S. aureus (MSSA) and MRSA BSI for Switzerland as well as the different linguistic regions within Switzerland. An additional aim was to estimate potential differences among patient-based and epidemiological risk factors.

METHODS

A retrospective observational study was conducted in Switzerland over a period of 14 years (2008-2021). Trends in S. aureus, MSSA and MRSA BSI were analysed by applying linear regression models.

RESULTS

Staphylococcus aureus BSI increased by + 30% from 19.7 to 25.6 cases per 100,000 inhabitants between 2008 and 2021 (P < 0.01) in Switzerland. Thereof, MSSA increased by + 37% from 17.8 to 24.4 cases per 100,000 inhabitants (P < 0.01). MRSA decreased from 1.9 to 1.2 cases per 100,000 inhabitants (P < 0.01), which was driven by decreasing incidence in the French-speaking region. MSSA BSI increased significantly (P < 0.01) in both linguistic regions. A further stratification revealed that incidence increased the most in male patients of the age group ≥ 80 years of the German-speaking region.

CONCLUSION

The increasing health burden of MSSA BSI in Switzerland indicates that not only proportions of resistant microorganisms but also total BSI incidences should be monitored. In addition, data stratification revealed that the increase was mainly driven by an increasing incidence in elderly males of the German-speaking region.

Multicenter Surveillance of Antimicrobial Resistance among Gram-Negative Bacteria Isolated from Bloodstream Infections in Ghana

BACKGROUND

Antimicrobial resistance (AMR) in Gram-negative bacteria-causing bloodstream infections (BSIs), such as Klebsiella pneumoniae and non-typhoidal Salmonella (NTS), is a major public health concern. Nonetheless, AMR surveillance remains scarce in sub-Saharan Africa, where BSI treatment is largely empirical. The aim of the study was to determine the distribution and AMR patterns of BSI-causing NTS, K. pneumoniae, and other Gram-negative bacteria in Ghana.

METHODS

A cross-sectional study was conducted between April and December 2021 at eleven sentinel health facilities across Ghana as part of a pilot study on the feasibility and implementation of the human sector AMR surveillance harmonized protocol in sub-Saharan Africa. Gram-negative bacteria recovered from blood specimens of febrile patients were identified using MALDI-TOF and evaluated for antimicrobial resistance using the BD Phoenix M50 analyzer and Kirby-Bauer disc diffusion. The Department of Medical Microbiology at the University of Ghana served as the reference laboratory.

RESULTS

Out of 334 Gram-negative blood isolates, there were 18 (5.4%) NTS, 85 (25.5%) K. pneumoniae, 88 (26.4%) Escherichia coli, 40 (12.0%) Acinetobacter baumannii, 25 (7.5%) Pseudomonas aeruginosa, and 77 (23.1%) other Gram-negative bacteria. As a composite, the isolates displayed high resistance to the antibiotics tested-amoxicillin (89.3%), tetracycline (76.1%), trimethoprim-sulfamethoxazole (71.5%), and chloramphenicol (59.7%). Resistance to third-generation cephalosporins [ceftriaxone (73.7%), cefotaxime (77.8%), and ceftazidime (56.3%)] and fluoroquinolones [ciprofloxacin (55.3%)] was also high; 88% of the isolates were multidrug resistant, and the rate of extended-spectrum beta-lactamase (ESBL) production was 44.6%. Antibiotic resistance in K. pneumoniae followed the pattern of all Gram-negative isolates. Antibiotic resistance was lower in NTS blood isolates, ranging between 16.7-38.9% resistance to the tested antibiotics. Resistance rates of 38.9%, 22.2%, and 27.8% were found for cefotaxime, ceftriaxone, and ceftazidime, respectively, and 27.8% and 23.8% for ciprofloxacin and azithromycin, respectively, which are used in the treatment of invasive NTS. The prevalence of multidrug resistance in NTS isolates was 38.9%.

CONCLUSIONS

Multicenter AMR surveillance of Gram-negative blood isolates from febrile patients was well-received in Ghana, and the implementation of a harmonized protocol was feasible. High resistance and multidrug resistance to first- or second-choice antibiotics, including penicillins, third-generation cephalosporins, and fluoroquinolones, were found, implying that these antibiotics might have limited effectiveness in BSI treatment in the country. Continuation of AMR surveillance in Gram-negative blood isolates is essential for a better understanding of the extent of AMR in these pathogens and to guide clinical practice and policymaking.

Staphylococcus aureus bacteraemia and mortality: a population-based study in Olmsted County, Minnesota, from 2006 to 2020

OBJECTIVES

To provide an evaluation of predictors of 6-month mortality in incident Staphylococcus aureus bacteraemia cases.

METHODS

A retrospective population-based study of 541 adult residents of Olmsted County, MN with monomicrobial S. aureus bacteraemia from 1 January 2006 through 31 December 2020. Multivariable Cox regression was used to investigate risk factors of 6-month mortality.

RESULTS

The median (interquartile range [IQR]) age of 541 patients with S. aureus bacteraemia was 66.8 (54.4-78.5) years and 39.6% were female. The median (IQR) Charlson Comorbidity Index was 6 (3-9). Overall, 144 patients died during the six-month period following their initial episode (30-day and 6-month mortality = 16.5% and 26.7%, respectively). In a multivariable analysis, older age, ICU admission, and unknown source of infection were significant predictors of increased 6-month mortality. In contrast, having an infectious diseases (ID) consultation was associated with reduced mortality in the first 2 weeks of follow-up. Secondary analyses revealed an early benefit of ID consultation during the first 30 days of follow-up and that infective endocarditis was an additional predictor of 6-month mortality.

CONCLUSIONS

To our knowledge, this investigation represents the only US population-based study evaluating predictors of mortality in patients with S. aureus bacteraemia. The finding of a short-term survival benefit associated with early ID consultation may be due to more extensive diagnostic efforts.

The Influence of Sex Hormones and X Chromosome in Immune Responses

Males and females differ in their susceptibility to develop autoimmunity and allergy but also in their capacity to cope with infections and cancers. Cellular targets and molecular pathways underlying sexual dimorphism in immunity have started to emerge and appeared multifactorial. It became increasingly clear that sex-linked biological factors have important impact on the development, tissue maintenance and effector function acquisition of distinct immune cell populations, thereby regulating multiple layers of innate or adaptive immunity through distinct mechanisms. This review discusses the recent development in our understanding of the cell-intrinsic actions of biological factors linked to sex, sex hormones and sex chromosome complement, on immune cells, which may account for the sex differences in susceptibility to autoimmune diseases and allergies, and the sex-biased responses in natural immunity and cancer.

Examining the clinical impact of rapid multiplex polymerase chain reaction-based diagnostic testing for bloodstream infections in a national cohort of the Veterans Health Administration

STUDY OBJECTIVE

Bloodstream infections (BSIs) are a significant cause of mortality. Use of a rapid multiplex polymerase chain reaction-based blood culture identification panel (BCID) may improve antimicrobial utilization and clinical outcomes by shortening the time to appropriate therapy and de-escalating antibiotics among patients on overly broad-spectrum empiric therapy. The effect of BCID on clinical outcomes across varying institutional antimicrobial stewardship program (ASP) practices is unclear. This study evaluated clinical outcomes associated with the "real-world" implementation of BCID in a national health system with varying ASP practices.

DESIGN

National, multicenter, retrospective, pre-post quasi-experimental study of hospitalized patients admitted from 2015 to 2020 to VHA facilities, which introduced the BCID for ≥1 year.

SETTING

United States Veterans Health Administration (VHA) hospitals with BCID.

PATIENTS

Hospitalized VHA patients with ≥1 blood culture positive for bacteria featured on the BCID panel.

INTERVENTION

Comparison of outcomes between the pre- and post-BCID implementation groups.

MEASUREMENTS

Outcomes evaluated included early antimicrobial de-escalation within 48 h, defined as reduction in antimicrobial spectrum scores, time to appropriate therapy, and 30-day mortality.

MAIN RESULTS

A total of 4138 patients (pre-BCID, n = 2100; post-BCID, n = 2038) met the study criteria. Implementation of BCID was associated with significant improvements in early antimicrobial de-escalation (34.6%: pre-BCID vs. 38.1%: post-BCID; p = 0.022), which persisted after adjusting for other covariates (adjusted risk ratio [aRR], 1.11; 95% confidence interval [CI], 1.02-1.20; p = 0.011). Median time to appropriate therapy was shorter in the post-BCID implementation group relative to the pre-BCID group (9 h: pre-BCID vs. 8 h: post-BCID, respectively, p = 0.005), and a greater percentage of patients received early appropriate antimicrobial therapy within 48 h in the post-BCID implementation group (91.7%: pre-BCID vs. 93.8%: post-BCID; p = 0.008). In the multivariable regression analysis, BCID implementation was significantly associated with a higher likelihood of appropriate therapy within 48 h (aRR, 1.02; 95% CI, 1.01-1.08; p = 0.020). There was no difference in 30-day mortality between groups overall (12.6% pre-BCID vs. 11.2% post-BCID; p = 0.211).

CONCLUSIONS

In a "real-world" clinical setting, the implementation of BCID was associated with clinical improvements in antimicrobial utilization. The BCID platform may serve as a useful adjunct for BSI management in facilities with ASP.

Impact of specialty on the self-reported practice of using oral antibiotic therapy for definitive treatment of bloodstream infections

Background:

No established guidelines exist regarding the role of oral antibiotic therapy (OAT) to treat bloodstream infections (BSIs), and practices may vary depending on clinician specialty and experience.

Objective:

To assess practice patterns regarding oral antibiotic use for treatment of bacteremia in infectious diseases clinicians (IDCs, including physicians and pharmacists and trainees in these groups) and non–infectious diseases clinicians (NIDCs).

Design:

Open-access survey.

Participants:

Clinicians caring for hospitalized patients receiving antibiotics.

Methods:

An open-access, web-based survey was distributed to clinicians at a Midwestern academic medical center using e-mail and to clinicians outside the medical center using social media. Respondents answered questions regarding confidence prescribing OAT for BSI in different scenarios. We used χ2 analysis for categorical data evaluated association between responses and demographic groups.

Results:

Of 282 survey responses, 82.6% of respondents were physicians, 17.4% pharmacists, and IDCs represented 69.2% of all respondents. IDCs were more likely to select routine use of OAT for BSI due to gram-negative anaerobes (84.6% vs 59.8%; P < .0001), Klebsiella spp (84.5% vs 69.0%; P < .009), Proteus spp (83.6% vs 71.3%; P < .027), and other Enterobacterales (79.5% vs 60.9%; P < .004). Our survey results revealed significant differences in selected treatment of Staphylococcus aureus syndromes. Fewer IDCs than NIDCs selected OAT to complete treatment for methicillin-resistant S. aureus (MRSA) BSI due to gluteal abscess (11.9% vs 25.6%; P = .012) and methicillin-susceptible S. aureus (MSSA) BSI due to septic arthritis (13.9% vs 20.9%; P = .219).

Conclusions:

Practice variation and discordance with evidence for the use of OAT for BSIs exists among IDCs versus NIDCs, highlighting opportunities for education in both clinician groups.

One-year mortality and years of potential life lost following bloodstream infection among adults: A nation-wide population based study

Background

Limited data exist on long-term consequences of bloodstream infections (BSIs). We aimed to examine incidence, 1-year mortality, and years of potential life lost (YPLL) following BSI. We estimated the relative contribution of hospital-onset BSI (HO-BSI) and antibiotic-resistant BSI to incidence, mortality and YPLL.

Methods

We used data from Israel's national BSI surveillance system (covering eight sentinel bacteria, comprising 70% of all BSIs) and the national death registry. Adults with BSI between January 2018 and December 2019 were included. The outcomes were all-cause 30-day and 1-year mortality, with no adjustment for co-morbidities. We calculated the age-standardized mortality rate and YPLL using the Global Burden of Disease reference population and life expectancy tables.

Findings

In total, 25,376 BSIs occurred over 2 years (mean adult population: 6,068,580). The annual incidence was 209·1 BSIs (95% CI 206·5–211·7) per 100,000 population. The case fatality rate was 25·6% (95% CI 25·0-26·2) at 30 days and 46·4% (95% CI 45·5-47·2) at 1 year. The hazard of death increased by 30% for each decade of age (HR=1·3 [95% CI 1·2-1·3]). The annual age-standardized mortality rate and YPLL per 100,000 were 50·8 (95% CI 49·7-51·9) and 1,012·6 (95% CI 986·9-1,038·3), respectively. HO-BSI (6,962 events) represented 27·4% (95% CI 26·9-28·0) of BSIs, 33·9% (95% CI 32·6-35·0) of deaths and 39·9% (95% CI 39·5-40·2) of YPLL. HO-BSI by drug-resistant bacteria (3,072 events) represented 12·1% (95% CI 11·7-12·5) of BSIs, 15·6% (95% CI 14·7-16·5) of deaths, and 18·4% (95% CI 18·1-18·7) of YPLL.

Interpretation

One-year mortality following BSI is high. The burden of BSI is similar to that of ischemic stroke. HO-BSI and drug-resistant BSI contribute disproportionately to BSI mortality and YPLL.

Funding

None.

Pcv-aCO2 and procalcitonin levels for the early diagnosis of bloodstream infections caused by gram-negative bacteria

BACKGROUND

The central venous-to-arterial carbon dioxide difference (Pcv-aCO₂) is a biomarker for tissue perfusion, but the diagnostic value of Pcv-aCO₂ in bacteria bloodstream infections (BSI) caused by gram-negative (GN) bacteria remains unclear. This study evaluated the expression levels and diagnostic value of Pcv-aCO₂ and procalcitonin (PCT) in the early stages of GN bacteria BSI.

METHODS

Patients with BSI admitted to the intensive care unit at Guangdong Provincial People's Hospital between August 2014 and August 2017 were enrolled. Pcv-aCO₂ and PCT levels were evaluated in GN and gram-positive (GP) bacteria BSI patients.

RESULTS

A total of 132 patients with BSI were enrolled. The Pcv-aCO₂ (8.32 ± 3.59 vs 4.35 ± 2.24 mmHg p = 0.001) and PCT (30.62 ± 34.51 vs 4.92 ± 6.13 ng/ml p = 0.001) levels were significantly higher in the GN group than in the GP group. In the diagnosis of GN bacteria BSI, the area under the receiver operating characteristic curve (AUROC) for Pcv-aCO₂ was 0.823 (95% confidence interval (CI): 0.746-0.900). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 71.90%, 88.00%, 74.07% and 78.21%, respectively. The AUROC for PCT was 0.818 (95% CI: 0.745-0.890). The sensitivity, specificity, PPV and NPV were 57.90%, 94.67%, 71.93% and 74.67%, respectively.

CONCLUSIONS

Pcv-aCO₂ and PCT have similar and high diagnostic value for the early diagnosis of BSI caused by GN bacteria.

Rapid and precise identification of bloodstream infections using a pre-treatment protocol combined with high-throughput multiplex genetic detection system

Background

Bloodstream infection (BSI) is a life-threatening condition with high morbidity and mortality rates worldwide. Early diagnosis of BSI is critical to avoid the unnecessary application of antimicrobial agents and for proper treatment. However, the current standard methods based on blood culture are time-consuming, thus failing to provide a timely etiological diagnosis of BSI, and common PCR-based detection might be inhibited by matrix components.

Methods

The current study explored an integrated pre-analytical treatment protocol for whole blood samples, wherein pathogens are enriched and purified by incubation and concentration, and inhibitors are inactivated and removed. Further, this study developed and evaluated a novel high-throughput multiplex genetic detection system (HMGS) to detect 24 of the most clinically prevalent BSI pathogens in blood culture samples and pre-treated whole blood samples. The specificity and sensitivity were evaluated using related reference strains and quantified bacterial/fungal suspensions. The clinical utility of BSI-HMGS combined with the pre-analytical treatment protocol was verified using blood cultures and whole blood samples.

Results

The combined pre-treatment protocol and BSI-HMGS was highly specific for target pathogens and possessed a low detection limit for clinical whole blood samples. The pre-treatment protocol could deplete the PCR inhibitors effectively. For blood culture samples, the current method showed 100.0% negative percent agreements and > 87.5% positive percent agreements compared to the reference results based on blood culture findings. For whole blood samples, the current method showed 100.0% negative percent agreements and > 80.0% positive percent agreements compared to the reference results for most pathogens. The turnaround time was ≤ 8 h, and all the procedures could be conducted in a general clinical laboratory.

Conclusion

The BSI-HMGS combined with the pre-treatment protocol was a practical and promising method for early and precise detection of BSIs, especially for areas without access to advanced medical facilities.

Development of a Multiplex Polymerase Chain Reaction-Based DNA Lateral Flow Assay as a Point-of-Care Diagnostic for Fast and Simultaneous Detection of MRSA and Vancomycin Resistance in Bacteremia

To reduce high mortality and morbidity rates, timely and proper treatment of methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection is required. A multiplex polymerase reaction (mPCR)-based DNA lateral flow assay (MBDLFA) was developed as a point-of-care diagnostic for simultaneous identification of S. aureus, methicillin resistance, and vancomycin resistance directly from blood or blood cultures. A mPCR was developed to detect nuc, mecA, and vanA/B; its sensitivity, specificity, and limit of detection (LOD) were determined. The developed reaction was further modified for use in MBDLFA and its sensitivity for detection of target genes from artificially inoculated blood samples was checked. The optimized mPCR successfully detected nuc, mecA, and vanA/B from genomic DNA of bacterial colonies with LODs of 107, 107, and 105 CFU/mL, respectively. The reaction was sensitive and specific. The optimized mPCR was used in MBDLFA that detected nuc, mecA, and vanA/B with LODs of 107, 108, and 104 CFU/mL, respectively, directly from artificially inoculated blood. The developed MBDLFA can be used as a rapid, cheap point-of-care diagnostic for detecting S. aureus, MRSA, and vancomycin resistance directly from blood and blood cultures in ~2 h with the naked eye. This will reduce morbidity, mortality, and treatment cost in S. aureus bacteremia.

Sepsityper® Kit versus In-House Method in Rapid Identification of Bacteria from Positive Blood Cultures by MALDI-TOF Mass Spectrometry

In order to further accelerate pathogen identification from positive blood cultures (BC), various sample preparation protocols to identify bacteria with MALDI-TOF MS directly from positive BCs have been developed. We evaluated an in-house method in comparison to the Sepsityper® Kit (Bruker Daltonics, Bremen, Germany) as well as the benefit of an on-plate formic acid extraction step following positive signal by the BACTECTM FX system. Confirmation of identification was achieved using subcultured growing biomass used for MALDI-TOF MS analysis. A total of 113 monomicrobial positive BCs were analyzed. The rates of Gram-positive bacteria correctly identified to the genus level using in-house method and Sepsityper® Kit were 63.3% (38/60) and 81.7% (49/60), respectively (p = 0.025). Identification rates at species level for Gram-positive bacteria with in-house method and Sepsityper® kit were 30.0% (18/60) and 66.7% (40/60), respectively (p < 0.001). Identification rates of Gram-negative bacteria were similar with the in-house method and Sepsityper® Kit. Additional on-plate formic acid extraction demonstrated significant improvement in the identification rate of Gram-positive bacteria at both genus and species level for both in-house (p = 0.001, p < 0.001) and Sepsityper® Kit methods (p = 0.007, p < 0.001). Our in-house method is a candidate for laboratory routines with Sepsityper® Kit as a back-up solution when identification of Gram-positive bacteria is unsuccessful.