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

Genetic Characterization of Multidrug-Resistant E. coli Isolates from Bloodstream Infections in Lithuania

Extraintestinal pathogenic Escherichia coli (ExPEC) isolates are a main cause of bloodstream infections. The aim of this study was to characterize 256 β-lactam–resistant, bacteremia-causing E. coli isolates collected from 12 healthcare institutions in Lithuania in 2014 and 2018. All isolates were identified as E. coli via MALDI-TOF MS and VITEK ®2. In addition, the isolates were analyzed for the presence of 29 resistance genes and 13 virulence genes, divided into phylogenetic groups (A, B1, B2, C, D, E, and F), and characterized using rep-PCR genotyping methods (BOX-PCR and (GTG)5-PCR). Analyzing the results of this study showed tetA-strB-sul2-TEM-NDM-strA-fosA-AIM-sul3-aadA-CTX-M-9 to be the most common resistance gene combination (67.2% of all isolates). Additionally, the most common virulence genes established were fimH (98.4% of all isolates), fyuA (91.8%), and traT (81.3%) and the most common gene combination was fuyA-fimH-iroN (58.6% of all isolates). Next, the isolates were separated into four phylogenetic groups: A, B1, B2, and F, where group A isolates were detected at a significantly higher frequency (79.3% of all isolates). Finally, a total of 235 genotyping profiles were established using rep-PCR methods, and all profiles were separated into fourteen genotypic clusters, with each cluster containing profiles with a variety of virulence and resistance genes not restricted to any specific cluster. The results of this study elucidate E. coli antimicrobial resistance patterns by highlighting the variability and diversity of resistance and virulence genes and providing phylogenetic classification, genetic profiling, and clustering data. These results may improve clinical control of multidrug-resistant infections in healthcare institutions and contribute to the prevention of potential outbreaks.

Pasteurella species bloodstream infections in Queensland, Australia, 2000-2019

Pasteurella species are infrequent but potentially severe causes of bloodstream infection (BSI). The objective of this study was to determine the incidence, risk factors, and outcomes of Pasteurella species BSI in a large Australian population. Retrospective, laboratory-based surveillance was conducted in Queensland, Australia (population ≈ 5 million) during 2000–2019, and clinical and outcome information was established by linkage to state hospital admissions and vital statistics databases. During more than 86 million person-years of surveillance, 272 incident Pasteurella species BSI occurred for an overall age- and sex-standardized annual incidence of 3.3 per million residents. The incidence of Pasteurella species BSI was highest in recent years and older individuals were at greatest risk. The median (interquartile range) Charlson Comorbidity Index was 2 (0–4) with scores of zero, 1, 2, and 3 + observed in 81 (30%), 37 (14%), 44 (16%), and 110 (40%) of cases. The 30-day all-cause case fatality was 9% (24/272) and patients who died had more comorbidities and were less likely to have community-associated disease. Although Pasteurella species are infrequent causes of BSI, older individuals and those with comorbidities are at highest risk. The burden of this disease may be expected to increase with an aging and more comorbid population.

Evaluation of step-down oral antibiotic therapy for uncomplicated streptococcal bloodstream infections on clinical outcomes

Background:

Despite the severity and frequency of streptococcal bloodstream infections (BSIs), the effectiveness of oral definitive therapy remains unknown. The objective of this study was to evaluate the clinical outcomes of step-down oral antibiotics for the treatment of uncomplicated streptococcal BSIs.

Methods:

In this retrospective cohort study, adult patients admitted with uncomplicated streptococcal BSI between June 2015 and June 2017 were included. Patients were excluded if they received <48 h of antibiotic therapy; therapy was started >48 h after first positive culture; had complicated infections of endocarditis, bone and joint infections, or central nervous system infections; Pitt bacteremia score (PBS) ⩾ 4; or failed to respond to effective therapy necessitating continued intravenous (IV) therapy. Patients were grouped by receipt of step-down oral antibiotic therapy (PO group) versus continued IV therapy (IV group). Outcomes included hospital length of stay (LOS), 30-day recurrence of BSI, 30-day readmission, 30-day all-cause mortality, and catheter-related or drug-related adverse events (AEs).

Results:

Of 244 patients included, 40% received step-down oral therapy (n = 98). Overall, the most common source of BSI was pneumonia (22%), followed by skin and soft tissue infections (SSTI) (18%). Severity of illness measured by intensive care unit (ICU) admission and PBS was similar. The IV group had significantly longer LOS [median 10 (interquartile range [IQR] = 5–21) versus 5 (4–6) days, p < 0.01] compared with the PO group. BSI recurrence, readmission, all-cause mortality within 30 days, and AEs were similar between the groups (p = ns).

Conclusion:

In uncomplicated streptococcal BSI, patients treated with step-down oral antibiotic therapy had significantly shorter LOS compared with continued IV therapy without compromise of clinical outcomes.

Antimicrobial Resistance and Molecular Epidemiology of Escherichia coli From Bloodstream Infection in Shanghai, China, 2016-2019

Background: Bloodstream infections are recognized as important nosocomial infections. Escherichia coli (E. coli) is the most prevalent Gram-negative bacillary pathogen causing bloodstream infections (BSIs). This retrospective study investigated drug susceptibility and molecular epidemiology of E. coli isolated from patients with BSI in Shanghai, China.

Methods: We collected E. coli isolated from the blood cultures of patients with BSI between January 2016 and December 2019. We randomly selected 20 strains each year to investigate antimicrobial resistance, resistance genes, and molecular epidemiological characteristics. Antimicrobial susceptibility testing was performed by the disk diffusion method. PCR was performed to detect extended-spectrum β-lactamases (ESBLs), carbapenemase genes, and housekeeping genes, and phyloviz was applied to analyze multilocus sequence typing (MLST).

Results: Penicillins, first- and second-generation cephalosporins and fluoroquinolones have high resistance rates (>60%). Among the 80 randomly selected strains, 47 (58.8%) produced ESBLs, and one produced carbapenemase. Sequencing of resistance genes identified bla_CTX−M−14 (34%, 16/47), bla_CTX−M−15 (23.4%, 11/47) and bla_CTX−M−27 (14.8%, 7/47) as the most prevalent genotypes of ESBLs. ST131 (14/80) was the most prevalent sequence type (ST), followed by ST1193 (10/80), ST648 (7/80).

Conclusions: Our findings suggest that amikacin, carbapenems, and piperacillin-tazobactam have relatively low resistance rates and may be the preferred antibiotic regimens for empiric therapy. ST131 and bla_CTX−M−14 are still the main prevalent in Shanghai with a rapid increase in the occurrence of ST1193 is rapidly increasing and more diverse bla_CTX genes.

Major Bloodstream Infection-Causing Bacterial Pathogens and Their Antimicrobial Resistance in South Korea, 2017-2019: Phase I Report From Kor-GLASS

To monitor national antimicrobial resistance (AMR), the Korea Global AMR Surveillance System (Kor-GLASS) was established. This study analyzed bloodstream infection (BSI) cases from Kor-GLASS phase I from January 2017 to December 2019. Nine non-duplicated Kor-GLASS target pathogens, including Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter spp., and Salmonella spp., were isolated from blood specimens from eight sentinel hospitals. Antimicrobial susceptibility testing, AMR genotyping, and strain typing were carried out. Among the 20,041 BSI cases, 15,171 cases were caused by one of the target pathogens, and 12,578 blood isolates were collected for the study. Half (1,059/2,134) of S. aureus isolates were resistant to cefoxitin, and 38.1% (333/873) of E. faecium isolates were resistant to vancomycin. Beta-lactamase-non-producing ampicillin-resistant and penicillin-resistant E. faecalis isolates by disk diffusion method were identified, but the isolates were confirmed as ampicillin-susceptible by broth microdilution method. Among E. coli, an increasing number of isolates carried the bla _CTX-M-27 gene, and the ertapenem resistance in 1.4% (30/2,110) of K. pneumoniae isolates was mostly (23/30) conferred by K. pneumoniae carbapenemases. A quarter (108/488) of P. aeruginosa isolates were resistant to meropenem, and 30.5% (33/108) of those carried acquired carbapenemase genes. Over 90% (542/599) of A. baumannii isolates were imipenem-resistant, and all except one harbored the bla _OXA-23 gene. Kor-GLASS provided comprehensive AMR surveillance data, and the defined molecular mechanisms of resistance helped us to better understand AMR epidemiology. Comparative analysis with other GLASS-enrolled countries is possible owing to the harmonized system provided by GLASS.

Blood bacterial resistant investigation collaborative system (BRICS) report: a national surveillance in China from 2014 to 2019

BACKGROUND

In this first national bloodstream infection (BSI) surveillance program in China, we assessed the composition of pathogenic bacteria and the trends for antimicrobial susceptibility over a 6-year period in China.

METHODS

Blood bacterial isolates from patients at hospitals participating in the Blood Bacterial Resistant Investigation Collaborative System (BRICS) were collected from January 2014 to December 2019. Only the first isolate of a species per patient was eligible over the full study period. Antibiotic-susceptibility testing was conducted by agar-dilution or broth-dilution methods as recommended by the Clinical and Laboratory Standards Institute (CLSI). WHONET 5.6 was used to analyze data.

RESULTS

During the study period, 27,899 bacterial strains were collected. Gram-positive organisms accounted for 29.5% (8244) of the species identified and Gram-negative organisms accounted for 70.5% (19,655). The most-commonly isolated organisms in blood cultures were Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, coagulase-negative Staphylococci, and Acinetobacter baumannii. The prevalence of multidrug-resistant organisms, such as E. coli, K. pneumoniae, A. baumannii was higher in tertiary hospitals, whereas extended-spectrum, β-lactamase-producing E. coli (ESBL-E. coli), carbapenem-resistant A. baumannii were more prevalent in economically-developing areas. The prevalence of methicillin-resistant S. aureus declined from 39.0% (73/187) in 2014 to 25.9% (230/889) in 2019 (p < 0.05). The prevalence of ESBL-E. coli dropped from 61.2% (412/673) to 51.0% (1878/3,683) over time (p < 0.05), and carbapenem-resistant E. coli remained low prevalence (< 2%; 145/9944; p = 0.397). In contrast, carbapenem-resistant K. pneumoniae increased markedly from 7.0% (16/229) in 2014 to 19.6% (325/1,655) in 2019 (p < 0.05).

CONCLUSION

E. coli and K. pneumoniae were the leading causes of BSI during the 6-year study period. The major resistant pathogens declined or remained stable, whereas carbapenem-resistant K. pneumoniae continued to increase, which poses a great therapeutic challenge for BSIs.

Recent advances in metal-organic framework-based materials for anti-staphylococcus aureus infection

The rapid spread of staphylococcus aureus (S. aureus) causes an increased morbidity and mortality, as well as great economic losses in the world. Anti-S. aureus infection becomes a major challenge for clinicians and nursing professionals to address drug resistance. Hence, it is urgent to explore high efficiency, low toxicity, and environmental-friendly methods against S. aureus. Metal-organic frameworks (MOFs) represent great potential in treating S. aureus infection due to the unique features of MOFs including tunable chemical constitute, open crystalline structure, and high specific surface area. Especially, these properties endow MOF-based materials outstanding antibacterial effect, which can be mainly attributed to the continuously released active components and the exerted catalytic activity to fight bacterial infection. Herein, the structural characteristics of MOFs and evaluation method of antimicrobial activity are briefly summarized. Then we systematically give an overview on their recent progress on antibacterial mechanisms, metal ion sustained-release system, controlled delivery system, catalytic system, and energy conversion system based on MOF materials. Finally, suggestions and direction for future research to develop and mechanism understand MOF-based materials are discussed in antibacterial application.

A 21-Year Survey of Escherichia coli from Bloodstream Infections (BSI) in a Tertiary Hospital Reveals How Community-Hospital Dynamics of B2 Phylogroup Clones Influence Local BSI Rates

This is a longitudinal study comprising 649 Escherichia coli isolates representing all 7,165 E. coli bloodstream infection (BSI) episodes recorded in a hospital (1996 to 2016). Strain analysis included clonal identification (phylogenetic groups/subgroups, STc131 subclades, pulsed-field gel electrophoresis [PFGE], and whole-genome sequencing [WGS]), antibiotic susceptibility (13 antibiotics), and virulence-associated genes (VAGs; 29 genes). The incidence of E. coli BSI increased from 1996 to 2016 (5.5 to 10.8 BSI episodes/1,000 hospitalizations, average 7 to 8/1,000). B2 isolates predominate (53%), with subgroups B2-I (STc131), B2-II, B2-IX, and B2-VI representing 25%, 25%, 14%, and 9%, respectively. Intertwined waves of community-acquired (CA) plus health care-associated and community-onset health care-associated (HCA) and hospital-acquired (HA) episodes of both B2 and non-B2 phylogroups occurred. A remarkable increase was observed only for B2-I-STc131 (C1/C2 subclades), with oscillations for other B2 subgroups and phylogroups throughout the years. Epidemic and persistent clones (comprising isolates with highly similar/identical PFGE types and genomes differing in 6 to 173 single nucleotide polymorphisms [SNPs]) of B2-I (STc131), B2-II (STc73), B2-III (STc127), B2-IX (STc95), and B2-VI (STc12) were recovered from different patients, most at hospital admission, for long periods (2 to 17 years), and extended-spectrum beta-lactamase (ESBL) producers or resistance to ciprofloxacin in B2 isolates was almost restricted to B2-I (STc131) subclade C. STc131 contributed to increasing the B2 rates but only transiently altered the E. coli population structure. The increase of E. coli BSI was determined by waves of CA+HCA BSI episodes that predate the waves of HA BSI. Besides the risk of hospital transmission that led to temporal increases in BSI, this study suggests that E. coli populations/clones from community-based healthy individuals may occasionally have an epidemic structure and provide a source of transmissible strains influencing the HA BSI incidence.

IMPORTANCE Sepsis is the third leading cause of mortality in Western countries and one of the Global Health Threats recognized by the WHO since 2017. Despite Escherichia coli constituting the most common cause of bloodstream infections (BSI), its epidemiology is not fully understood, in part due to the scarcity of local and longitudinal studies. Our work analyzes the long-term dynamics of E. coli causing bacteremia in a single institution and reveals waves of different clonal lineages that emerge periodically and successfully spread afterward in both the community and hospitals. Because the origin of E. coli bloodstream infections is the gut, the microbiota of healthy individuals might occasionally have an epidemic structure, providing a source of E. coli strains to influence the incidence of hospital BSI. The study complements previous fractionated observations focusing on specific E. coli lineages or antibiotic-resistant isolates in the last decades and helps to understand the epidemiology of E. coli BSI and the dynamics of pandemic clones.

Antibiotic potentiating action of α-PINENE and borneol against EPEC and ETEC sorotypes

Escherichia coli is considered the main cause of intestinal and extra-intestinal infections, they have virulence mechanisms in different pathotypes and the ability to receive or transmit antimicrobial resistance genes. The aim of this work was to investigate the antibacterial and antimicrobial modulating activity of α-pinene and borneol against E. coli and enteropathogenic (EPEC) and enterotoxigenic (ETEC) serotypes. The broth microdilution methodology with multidrug-resistant Escherichia coli, EPEC and ETEC was used to determine the Minimum Inhibitory Concentration (MIC) and evaluation of the modulating activity of antibiotics (ciprofloxacin, sulfamethoxazole-trimethoprim and metronidazole) of α-pinene and borneol. It was concluded that α-pinene and borneol showed a low antimicrobial action against multi-resistant E. coli, however, this action was not observed against the EPEC and ETEC serotypes. A synergistic action of borneol associated with ciprofloxacin against ETEC was noted.

A longitudinal population-based study of predictors of mortality from bloodstream infections in Calgary, Alberta, Canada

Aim: To study the predictors of mortality from nine major pathogens causing approximately 70% of cases over a 7-year period. Materials & methods: A population-based surveillance cohort of all adult and pediatric patients in the Calgary Zone with an initial episode of bloodstream infections (BSI). Results: The 1-year mortality was 29.2% among 9524 patients (5164 males [54%]). Incidence rates for BSI increased annually to 119.7/100,000 persons by 2016. Distinct survival curves were found for each specific pathogen. Age, comorbidity burden and infecting organism were significantly associated with increased hazard of death. No relationship occurred between the time to positivity for blood cultures and overall mortality. Conclusion: BSI has a high mortality, but overall survival depends on underlying host health and the type of pathogen acquired.

Bloodstream Infection and Endocarditis Caused by Staphylococcus aureus in Patients with Cancer: A Multicenter Cohort Study

INTRODUCTION

In a large cohort of patients with Staphylococcus aureus bloodstream infection (SABSI), we aimed to analyze the incidence and risk factors for infective endocarditis (IE) among patients with active cancer (PAC) in comparison with those without cancer (PWC).

METHODS

Multicenter cohort study of patients with SABSI admitted to two tertiary care hospitals, from 2011 to 2019. PAC were defined as those with an active solid organ cancer or hematological malignancies. SABSI and S. aureus IE were compared between PAC and PWC.

RESULTS

Among 978 episodes of SABSI, 217 (22.2%) occurred in PAC. PAC were younger, had fewer comorbidities, carried cardiac devices less often, and had less community-acquired SABSI than PWC. Compared to PWC, PAC more frequently had catheter-related SABSI, less IE (2.8% vs 10.9%, p < 0.001) and osteoarticular infection (2.3% vs 14.3%, p < 0.001). Independent risk factors for IE were cardiopathy (aOR 4.392, 95% CI 2.719-7.094) and persistent bacteremia (aOR 3.545, 95% CI 2.159-5.820). Thirty-day mortality was high, and similar between groups (24.2% vs 25.5%, p = 0.282).

CONCLUSIONS

PAC with SABSI developed IE less frequently than PWC did. This finding seems related to the differences in baseline characteristics and may have significant clinical implications, such as transesophageal echocardiography in PAC without cardiopathy or persistent bacteremia.

Population-based epidemiology of Escherichia coli ST1193 causing blood stream infections in a centralized Canadian region

Escherichia coli ST1193 is an emerging global clone associated with fluoroquinolone resistance. A population-based study described genomics, clinical factors, susceptibility patterns, and incidence rates of ST1193 (n = 69) causing incident blood stream infections in a centralized Canadian region 2016-18. ST1193 was responsible for community-acquired upper urinary tract infections among the elderly. The incidence rate (IR) per 100,000 person-years among Calgary residents increased from 1.0 (95%confidence interval [95%CI] 0.7-1.5) in 2016, to 1.7 (95%CI 1.3-2.3) in 2018 (p = 0.05). This was mainly due to the significant increase of ST1193 blood stream infections among female long-term care (LTC) residents. ST1193 IR with blaCTX-Ms was 3.18 times higher in 2018 than in 2016 (CI 95% 0.98-13.49). We identified a ST1193 isolate with only a parC S80I mutation that is different from previously published data. The population-based study identified a significant increase over a 2-year period of E. coli ST1193 blood stream infections among elderly females residing in LTC centers. There was also a notable increase of ST1193 with bla CTX-Ms in 2018. The rapid emergence of ST1193 is concerning and adding to the public health burden of multidrug resistant E. coli blood stream infections in Calgary.

Comparison of Risk Factors and Outcomes in Carbapenem-Resistant and Carbapenem-Susceptible Gram-Negative Bacteremia

Background:

Carbapenem-resistant Gram-negative bacteremia (CR-GNB) is seen with increasing frequency and result in high mortality. The aim of this study was to compare the risk factors and results of carbapenem-resistant and carbapenem-susceptible Gram-negative bacteremia and to determine the factors related to mortality.

Methods:

The study was conducted as a retrospective observational comparative case series between June 2016 and November 2017 in Şişli Hamidiye Etfal Training and Research Hospital. The patients were divided into two groups as carbapenem-susceptible and carbapenem-resistant according to antibiotic susceptibility data of blood cultures. The risk factors for the development of carbapenem resistance, length of hospital stay, mortality rates, and mortality related factors were investigated between these two groups.

Results:

Two hundred and eleven cases were included in the study. Of these cases, 54 were resistant to carbapenem and 157 were susceptible to carbapenem. Mortality occurred in 60 (28.4%) patients. The 14 and 28 day mortality rates of patients with carbapenem resistance were significantly higher than those without carbapenem resistance. There was no statistically significant difference between two groups in length of stay in the hospital after bacteremia. Pittsburgh bacteremia score, cardiovascular disease, urinary catheterization, and inappropriate empirical antibiotic therapy were the most significant risk factors for mortality.

Conclusions:

Carbapenem resistance is associated with increased mortality and inappropriate empirical antibiotic treatment increases mortality. Therefore, patients should be evaluated for risk factors in predicting CR-GNB and treatment for resistant pathogens should be applied in appropriate patients.

Bacterial Etiology of Bloodstream Infections and Antimicrobial Resistance Patterns from a Tertiary Care Hospital in Malé, Maldives

Background

Bloodstream infections pose a significant health problem worldwide and is a major cause of morbidity and mortality in many countries. It is important to have country-specific data for major pathogens causing bloodstream infections, in light of emerging resistance patterns of common bacterial isolates. Due to the scarcity of reports in this area, the aim of this study was to identify bacterial pathogens causing bloodstream infections among the study population.

Methods

A retrospective analysis of blood culture samples received at the Department of Laboratory Medicine, Indira Gandhi Memorial Hospital, Malé, Maldives, was performed for reports between January 2016 and December 2017.

Results

Out of the 471 culture-positive samples, 278 (59%) were males and 193 (41%) were females. Amongst the culture-positive samples, 338 (71.8%) Gram-positive organisms were isolated and 133 (28.2%) Gram-negative organisms were isolated. Coagulase-negative Staphylococcus (CoNS) was the most frequently isolated blood-borne bacterial pathogen in this study, accounting for 53.6% and 50.9% of the isolates in 2016 and 2017, respectively. Other frequently isolated pathogens included Staphylococcus aureus (15.9% and 10.3%), Klebsiella spp. (10.5% and 16.4%), and Escherichia coli (7.1% and 10.8%). Coagulase-negative Staphylococcus (CoNS) revealed high percentage of resistance among the tested antimicrobials, ampicillin, cephalexin, cefotaxime, and gentamicin. Over the two years, a significant difference between the percentage resistance among paediatric and adult patients was observed for coagulase-negative Staphylococcus (CoNS) isolate resistance to ampicillin (p ≤ 0.001), cephalexin (p ≤ 0.001), cefotaxime (p ≤ 0.001), gentamicin (p=0.008), and cotrimoxazole (SXT) (p ≤ 0.001). When comparing the significant antimicrobial resistance trends, it can be seen that Enterobacteriaceae isolates also demonstrated high resistance to ampicillin and gentamicin as well as second- and third-generation cephalosporins.

Conclusions

This study highlights the major bacterial pathogens involved in bloodstream infections in the healthcare setting of Malé, Maldives, and antibiotic resistance patterns. The results indicate that further characterization of bacteremia and its resistance patterns is needed to combat bloodstream infections.

Prognostic Effects of Delayed Administration of Antimicrobial Therapy in Older Persons Experiencing Bacteremia With or Without Initial Sepsis Presentations

OBJECTIVES

To investigate the prognostic effects of delayed administration of appropriate antimicrobial therapy (AAT) in older persons experiencing bacteremia with and without initial sepsis syndrome, respectively.

DESIGN

A 4-year multicenter cohort study.

SETTING AND PARTICIPANTS

Older people (≥65 years of age) with community-onset bacteremia in the emergency department (ED) of 3 participating hospitals.

METHODS

Clinical data were retrospectively collected and causative microorganisms were prospectively collected for susceptibilities to determine the period of delayed AAT for each bacteremia episode. Sepsis was defined based on the Sepsis-3 criteria. A multivariable regression model was used to investigate the prognostic effects of delayed AAT, after adjusting independent determinants of 30-day mortality.

RESULTS

Of the total 2357 patients, their median (interquartile range) age was 78 (72-84) years and septic patients accounted for 48.4% (1140 patients) of the overall patients. Compared with nonseptic patients, septic individuals exhibited the shorter period of delayed AAT (median, 2.0 vs 2.5 hours; P < .001), longer hospitalization (median, 11 vs 9 days; P < .001), and higher crude mortality rates at 15 (28.9% vs 2.1%; P < .001) and 30 days (34.6% vs 4.0%; P < .001). In multivariable regression analyses, each hour of delayed AAT resulted in average increases in the 30-day crude mortality rates of 0.38% [adjusted odds ratio (AOR) 1.0038; P < .001), 0.42% (AOR 1.0042; P < .001), and 0.31% (AOR 1.0031; P = .04) among overall, septic, and nonseptic patients, respectively.

CONCLUSIONS AND IMPLICATIONS

For older persons with community-onset bacteremia, irrespective of whether or not patients experiencing initial sepsis presentations, the prognostic impacts of delayed AAT have been evidenced. Notably, because of the longer period of delayed AAT in patients without fulfilling the Sepsis-3, adopting a stricter sepsis definition and/or early bacteremia predictor to avoid delayed AAT and unfavorable prognoses in patients with bacteremia is necessary.

Functional Mapping of Phenotypic Plasticity of Staphylococcus aureus Under Vancomycin Pressure

Phenotypic plasticity is the exhibition of various phenotypic traits produced by a single genotype in response to environmental changes, enabling organisms to adapt to environmental changes by maintaining growth and reproduction. Despite its significance in evolutionary studies, we still know little about the genetic control of phenotypic plasticity. In this study, we designed and conducted a genome-wide association study (GWAS) to reveal genetic architecture of how Staphylococcus aureus strains respond to increasing concentrations of vancomycin (0, 2, 4, and 6 μg/mL) in a time course. We implemented functional mapping, a dynamic model for genetic mapping using longitudinal data, to map specific loci that mediate the growth trajectories of abundance of vancomycin-exposed S. aureus strains. 78 significant single nucleotide polymorphisms were identified following analysis of the whole growth and development process, and seven genes might play a pivotal role in governing phenotypic plasticity to the pressure of vancomycin. These seven genes, SAOUHSC_00020 (walR), SAOUHSC_00176, SAOUHSC_00544 (sdrC), SAOUHSC_02998, SAOUHSC_00025, SAOUHSC_00169, and SAOUHSC_02023, were found to help S. aureus regulate antibiotic pressure. Our dynamic gene mapping technique provides a tool for dissecting the phenotypic plasticity mechanisms of S. aureus under vancomycin pressure, emphasizing the feasibility and potential of functional mapping in the study of bacterial phenotypic plasticity.

Epidemiology of Invasive Escherichia coli Infection and Antibiotic Resistance Status Among Patients Treated in US Hospitals: 2009-2016

BACKGROUND

Published data is limited on the prevalence and risk of recurrence of extraintestinal invasive Escherichia coli infections (IEIs) in the United States.

METHODS

The analysis included all inpatient and hospital-based outpatient visits occurring between 2009 and 2016 at hospitals with continuous microbiology data submission to the Premier Healthcare Database for 90 days before and 12 months after the admission or visit. IEI was defined as having positive E. coli culture from a normally sterile site (eg, blood, cerebrospinal fluid). The prevalence of IEI, 12-month risk of recurrent IEI, and antibiotic resistance were assessed.

RESULTS

Overall, 144 944 725 hospital visits among 37 207 510 patients were analyzed, and 71 909 IEI events occurred in 67 583 patients, corresponding to an IEI prevalence of 0.50 events per 1000 visits and 1.82 events per 1000 patients. Recurrence was common: 26.9 per 1000 patients had a recurrent IEI in the 12 months after their infection. Most infections were community acquired (66.4%), and urosepsis was most common clinical syndrome (66.0%). The 30-day risk of IEI among patients undergoing transrectal ultrasound-guided prostate biopsy was high: 5.03 events per 1000 patients. Among all IEI cases with antibiotic susceptibility testing, 9.18% were resistant to extended-spectrum cephalosporins, 28.22% to fluoroquinolones, and 0.14% to carbapenems. Resistance to extended-spectrum cephalosporins increased from 5.46% to 12.97% during the 8-year study period.

CONCLUSIONS

This real-world study indicates a substantial burden of IEI and recurrent IEI exists in the United States, as well as increasing resistance to extended-spectrum cephalosporins. Future research should explore risk factors of recurrent IEI aiming to effectively prevent such infections.

Analysis of Porcine Model of Fecal-Induced Peritonitis Reveals the Tropism of Blood Microbiome

Recent studies have suggested the existence of a blood microbiome in the healthy host. However, changes in the blood microbiome upon bloodstream infection are not known. Here, we analyzed the dynamics of the blood microbiome in a porcine model of polymicrobial bacteremia induced by fecal peritonitis. Surprisingly, we detected bacterial populations in the bloodstream even before the infection, and these populations were maintained over time. The native blood microbiome was notably taxonomically different from the fecal microbiome that was used to induce peritonitis, reflecting microbial tropism for the blood. Although the population composition after the infection was similar to that of the native blood microbiome, new bacterial strains entered the bloodstream upon peritonitis induction as clinical symptoms relevant to sepsis developed. This indicates that the bacteria detected in the blood before peritonitis induction were derived from the blood rather than a contamination. Comparison of the functional pathways enriched in the blood and fecal microbiomes revealed that communication and stress management pathways are essential for the survival of the blood microbiome.

The epidemiology of bloodstream infections and antimicrobial susceptibility patterns in Thuringia, Germany: a five-year prospective, state-wide surveillance study (AlertsNet)

Background

Monitoring pathogens of bloodstream infections (BSI) and their antibiotic susceptibility is important to guide empiric antibiotic treatment strategies and prevention programs.

This study assessed the epidemiology of BSI and antibiotic resistance patterns at the German Federal State of Thuringia longitudinally.

Methods

A surveillance network consisting of 26 hospitals was established to monitor BSIs from 01/2015 to 12/2019. All blood culture results, without restriction of age of patients, of the participating hospitals were reported by the respective microbiological laboratory. A single detection of obligate pathogens and a repeated detection of coagulase-negative staphylococci, Bacillus spp., Corynebacterium spp., Micrococcus spp. and Propionibacterium spp., within 96 h were regarded as a relevant positive blood culture. If one of the aforementioned non-obligate pathogens has been detected only once within 96 h, contamination has been assumed. Logistic regression models were applied to analyse the relationship between resistance, year of BSI and hospital size. Generalized estimating equations were used to address potential clustering.

Results

A total of 343,284 blood cultures (BC) of 82,527 patients were recorded. Overall, 2.8% (n = 9571) of all BCs were classified as contaminated. At least one relevant pathogen was identified in 13.2% (n = 45,346) of BCs. Escherichia coli (25.4%) was the most commonly detected pathogen, followed by Staphylococcus aureus (15.2%), Staphylococcus epidermidis (8.1%) and Klebsiella pneumoniae (4.6%). In S. aureus, we observed a decline of methicillin resistance (MRSA) from 10.4% in 2015 to 2.5% in 2019 (p < 0.001). The rate of vancomycin resistance in Enterococcus faecium (VRE) has increased from 16.7% in 2015 to 26.9% in 2019 (p < 0.001), with a peak in 2018 (42.5%). In addition, we observed an increase of Cefotaxime (3GC) resistance in E. coli from 10.7% in 2015 to 14.5% in 2019 (p = 0.007) whereas 3GC resistance in K. pneumoniae was stable (2015: 9.9%; 2019: 7.4%, p = 0.35). Carbapenem resistance was less than 1% for both pathogens. These patterns were robustly observed across sensitivity analyses.

Conclusions

We observed evidence for a decline in MRSA, an increase in VRE and a very low rate of carbapenem resistance in gram-negative bacteria. 3GC resistance in E. coli increased constantly over time.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00997-6.

Increasing incidence and antimicrobial resistance in Escherichia coli bloodstream infections: a multinational population-based cohort study

BACKGROUND

Escherichia coli is an important pathogen in humans and is the most common cause of bacterial bloodstream infections (BSIs). The objectives of our study were to determine factors associated with E. coli BSI incidence rate and third-generation cephalosporin resistance in a multinational population-based cohort.

METHODS

We included all incident E. coli BSIs (2014-2018) from national (Finland) and regional (Australia [Canberra], Sweden [Skaraborg], and Canada [Calgary, Sherbrooke, and western interior]) surveillance. Incidence rates were directly age and sex standardized to the European Union 28-country 2018 population. Multivariable negative binomial and logistic regression models estimated factors significantly associated with E. coli BSI incidence rate and third-generation cephalosporin resistance, respectively. The explanatory variables considered for inclusion in both models were year (2014-2018), region (six areas), age (< 70-years-old and ≥ 70-years-old), and sex (female and male).

RESULTS

We identified 31,889 E. coli BSIs from 40.7 million person-years of surveillance. Overall and third-generation cephalosporin-resistant standardized rates were 87.1 and 6.6 cases/100,000 person-years, respectively, and increased 14.0% and 40.1% over the five-year study. Overall, 7.8% (2483/31889) of E. coli BSIs were third-generation cephalosporin-resistant. Calgary, Canberra, Sherbrooke, and western interior had significantly lower E. coli BSI rates compared to Finland. The significant association between age and E. coli BSI rate varied with sex. Calgary, Canberra, and western interior had significantly greater odds of third-generation cephalosporin-resistant E. coli BSIs compared to Finland. Compared to 2014, the odds of third-generation cephalosporin-resistant E. coli BSIs were significantly increased in 2016, 2017, and 2018. The significant association between age and the odds of having a third-generation cephalosporin-resistant E. coli BSI varied with sex.

CONCLUSIONS

Increases in overall and third-generation cephalosporin-resistant standardized E. coli BSI rates were clinically important. Overall, E. coli BSI incidence rates were 40-104% greater than previous investigations from the same study areas. Region, sex, and age are important variables when analyzing E. coli BSI rates and third-generation cephalosporin resistance in E. coli BSIs. Considering E. coli is the most common cause of BSIs, this increasing burden and evolving third-generation cephalosporin resistance will have an important impact on human health, especially in aging populations.

Escherichia coli bloodstream infections in the western interior of British Columbia, Canada: a population-based cohort study

Our population-based study objectives were to describe characteristics and outcomes of Escherichia coli bloodstream infections (BSIs), and to evaluate factors associated with outcomes. We included incident E. coli BSIs from western interior residents (British Columbia, Canada; 04/2010–03/2020). We obtained data including patient demographics, location of onset, infection focus, Charlson comorbidity index (CCI), antimicrobial resistance, 30-day all-cause mortality and length of hospital stay (LOS). Using multivariable logistic regression models fitted with generalised estimating equations, we estimated factors associated with 30-day mortality and long post-infection LOS (>75th percentile). We identified 1080 incident E. coli BSIs in 1009 patients. The crude incidence and 30-day mortality rates were 59.1 BSIs and 6.8 deaths/100 000 person-years, respectively. The 30-day case fatality risk was 11.5%. Compared to community-acquired E. coli BSIs, either healthcare-associated or nosocomial cases had higher odds of 30-day mortality. Older cases, non-urogenital BSI foci and CCI ⩾ 3 had higher odds of 30-day mortality compared to younger cases, urogenital foci and CCI < 3. In patients that survived to discharge, those with extended-spectrum β-lactamase (ESBL)-producing E. coli BSIs, nosocomial BSIs, and CCI ⩾ 3 had higher odds of long post-infection LOS compared to those with non-ESBL-producing, community-acquired and healthcare-associated, and CCI < 3. There is a substantial disease burden from E. coli BSIs.

Combined procalcitonin and hemogram parameters contribute to early differential diagnosis of Gram-negative/Gram-positive bloodstream infections

Background

Hemogram parameters and procalcitonin (PCT) play auxiliary roles in the diagnosis and outcome of sepsis. However, it is not clear whether these indicators can quickly distinguish bacterial classification or guide the choice of empirical antibiotics.

Methods

We retrospectively enrolled 381 patients with bloodstream infections (BSI), divided into Gram‐positive bloodstream infections (GP‐BSI) and Gram‐negative bloodstream infections (GN‐BSI). Demographic parameters, hemogram parameters, and PCT were recorded and compared between the two groups.

Results

The mean platelet volume (MPV), platelet distribution width (PDW), and PCT in the GN‐BSI group were significantly higher than those in the GP‐BSI group, while the platelet count (PLT), plateletcrit, platelet count‐to‐white blood cell count ratio (PWR), platelet count‐to‐neutrophil count ratio (PNR), platelet count‐to‐PCT ratio (PLT/PCT), and mean platelet volume‐to‐PCT ratio (MPV/PCT) were significantly lower in the GN‐BSI group. Multivariate stepwise logistic regression analysis revealed that the independent predictors of GN‐BSI were MPV, PWR, and PCT. The areas under the curve (AUC) for this prediction model was 0.79, with sensitivity =0.75 and specificity =0.71.

Conclusions

There were significant differences in terms of PCT, platelet parameters, and platelet‐related index‐PCT ratio between GN‐BSI and GP‐BSI. Combined PCT and hemogram parameters are more conducive to the early differential diagnosis of bacterial classification of BSI.

Bacterial profile, antimicrobial susceptibility patterns, and associated factors among bloodstream infection suspected patients attending Arba Minch General Hospital, Ethiopia

Bacterial bloodstream infections are of great concern globally. Of late, the emergence of drug resistant bacteria worsen the related morbidity and mortality. This study was aimed to determine the bacterial profile, antimicrobial susceptibility patterns, and associated factors among the blood stream infection (BSI) suspected patients attending the Arba Minch General Hospital (AMGH), southern Ethiopia, from 01 June through 31st August, 2020. A cross-sectional study was conducted among 225 BSI suspected patients. Systematic random sampling method was used to select patients. Blood culture was done to isolate bacterial pathogens. Antimicrobial susceptibility test was performed by employing the Kirby-Bauer disc diffusion method. Descriptive statistics and multivariable logistic regression analysis were done by Statistical Package for Social Service (SPSS) version 22. The rate of prevalence of bacteriologically confirmed cases was 22/225 (9.8%). Majority of BSI were caused by Gram-positive cocci, 13/22 (59.1%), particularly the isolates of S. aureus, 7/22 (31.8%) followed by Enterococci species, 4/22 (18.2%) and coagulase-negative Staphylococci (CoNS), 2/22 (9.1%). Among the Gram-negative bacteria 9/22 (41.1%), Klebsiella species 4/22 (18.2%) was the prominent one followed by Escherichia coli 2/22 (9.1%), Pseudomonas aeruginosa 2/22 (9.1%), and Enterobacter species 1/22 (4.5%). All the isolates of Gram-negative bacteria were susceptible to meropenem whereas 69.2% of the isolates of Gram-positive counterparts were susceptible to erythromycin. Slightly above two third (68.2%) of the total isolates were multidrug resistant. Insertion of a peripheral intravenous line was significantly associated with BSI [p = 0.03; Adjusted Odds Ratio = 4.82; (Confidence Interval: 1.08-21.46)]. Overall results revealed that eventhough the prevalence of BSI in Arba Minch is comparatively lower (9.8%), multidrug resistance is alarmingly on the rise, which is to be addressed through effective surveillance and control strategies.

Bloodstream infections in head and neck cancer patients after curative-intent radiotherapy: a population-based study from the Danish Head and Neck Cancer Group database

BACKGROUND

Patients with head and neck squamous cell carcinoma (HNSCC) undergoing radiotherapy (RT) or chemoradiation (CRT) may become immunocompromised. In this population-based study, we aimed to investigate the risk factors, microbiological aetiologies, prognosis and impact on early non-cancer mortality of bloodstream infections (BSIs) after RT/CRT.

METHODS

Patients with HNSCC of the pharynx, larynx and oral cavity treated with curative-intent RT/CRT in Denmark between 2010 and 2017 and subsequent BSI episodes occurring within 18 months of RT/CRT initiation were identified in national registries.

RESULTS

We included 5674 patients and observed 238 BSIs. Increasing age, stage and performance status were significantly associated with an elevated BSI risk, while sex, smoking and high-grade mucositis were not. Human papillomavirus-positive oropharyngeal cancer patients had a decreased risk. Staphylococcus aureus accounted for 34% of episodes occurring during the first 3 months. The 30-day post-BSI mortality rate was 26% (95% confidence interval: 19-32) and BSIs were involved in 10% of early non-cancer deaths.

CONCLUSION

The risk of BSI development is associated with several patient- and disease-related factors and BSIs contribute considerably to early non-cancer mortality. Empiric antibiotic treatment regimens should prioritise coverage for S. aureus when treating suspected systemic infection in this population.

Repurposed drugs block toxin-driven platelet clearance by the hepatic Ashwell-Morell receptor to clear Staphylococcus aureus bacteremia

Staphylococcus aureus (SA) bloodstream infections cause high morbidity and mortality (20 to 30%) despite modern supportive care. In a human bacteremia cohort, we found that development of thrombocytopenia was correlated to increased mortality and increased α-toxin expression by the pathogen. Platelet-derived antibacterial peptides are important in bloodstream defense against SA, but α-toxin decreased platelet viability, induced platelet sialidase to cause desialylation of platelet glycoproteins, and accelerated platelet clearance by the hepatic Ashwell-Morell receptor (AMR). Ticagrelor (Brilinta), a commonly prescribed P2Y12 receptor inhibitor used after myocardial infarction, blocked α-toxin-mediated platelet injury and resulting thrombocytopenia, thereby providing protection from lethal SA infection in a murine intravenous challenge model. Genetic deletion or pharmacological inhibition of AMR stabilized platelet counts and enhanced resistance to SA infection, and the anti-influenza sialidase inhibitor oseltamivir (Tamiflu) provided similar therapeutic benefit. Thus, a "toxin-platelet-AMR" regulatory pathway plays a critical role in the pathogenesis of SA bloodstream infection, and its elucidation provides proof of concept for repurposing two commonly prescribed drugs as adjunctive therapies to improve patient outcomes.

Cefazolin versus ceftriaxone as definitive treatment for Klebsiella pneumoniae bacteraemia: a retrospective multicentre study in Singapore

BACKGROUND

Ceftriaxone is the preferred treatment for bacteraemia caused by non-MDR (antibiotic-susceptible) Klebsiella pneumoniae. Excessive and widespread ceftriaxone use creates selection pressure for ESBLs. Cefazolin is an alternative, although there are theoretical concerns that SHV-1 β-lactamase in K. pneumoniae may inactivate cefazolin in an inoculum-dependent manner.

OBJECTIVES

In this retrospective study, we investigated the outcomes in K. pneumoniae bacteraemia patients treated with IV cefazolin versus IV ceftriaxone as definitive therapy.

METHODS

A total of 917 patients infected with K. pneumoniae from 1 January to 31 December 2016 in three public acute care hospitals in Singapore were screened for study eligibility. Consecutive unique episodes of monomicrobial bacteraemia caused by cefazolin- and/or ceftriaxone-susceptible K. pneumoniae were analysed (n = 284).

RESULTS

There were 143 patients (50.4%) in the cefazolin group and 141 patients (49.6%) in the ceftriaxone group. Demographics, baseline illness severity and risk factors for healthcare-associated bacteraemia were comparable in the two treatment groups. The primary outcome of 28 day all-cause mortality was not significantly different between the cefazolin and ceftriaxone groups (10.5% versus 7.1%, P = 0.403). Both in the crude analysis and using a multivariable logistic regression model with inverse probability weighting based on propensity score, cefazolin treatment was not associated with increased risk of 28 day mortality (OR 1.51 with ceftriaxone as the reference group, 95% CI 0.67-3.53; adjusted OR 1.55, 95% CI 0.33-7.40).

CONCLUSIONS

Cefazolin may be a ceftriaxone-sparing alternative treatment for antibiotic-susceptible K. pneumoniae bacteraemia. This observation may provide sufficient clinical equipoise for a randomized controlled trial.

Identification and Antibiotic Susceptibility Patterns of Clinical Blood Culture Isolates Not Identified by a Rapid Microarray Diagnostic System

The use of molecular-based diagnostic testing, such as the Luminex Verigene system, to rapidly identify the most common bacterial isolates from blood cultures is an important tool that reduces the duration of inappropriate antibiotics and decreases mortality. However, 5 to 15% of microorganisms recovered from blood culture are unable to be identified by the Verigene Gram-negative (BC-GN) or Gram-positive (BC-GP) assays. In this retrospective, observational study, we evaluate the identities and antimicrobial susceptibility patterns of 229 isolates that were not identified by either the Verigene BC-GN or BC-GP assay. The results presented here suggest that important, clinically relevant information about antimicrobial susceptibility patterns can still be inferred even when isolates are not identified by Verigene. We also examined changes in antibiotic use for patients with “unidentified” Verigene results at our institution and found that this subgroup represents an opportunity to optimize empirical antibiotic therapy.

IMPORTANCE Rapid diagnostic testing to identify bloodstream pathogens has arisen as an important tool both to ensure adequate antimicrobial therapy is given early and to aid in antimicrobial stewardship by allowing for more rapid deescalation of inappropriate antimicrobial therapy. However, there is a paucity of data regarding the significance of isolates that are not able to be identified by rapid diagnostic testing. In this study, we report the identification to the species level and antimicrobial susceptibilities among isolates that were not identified by one such rapid diagnostic platform, the Verigene system. This study provides important insight into how a strong understanding of the strengths and limitations of a given rapid diagnostic platform, coupled with insight into local antibiotic susceptibility patterns, can allow for more nuanced and thoughtful empirical antibiotic selection.

Mortality in Escherichia coli bloodstream infections: a multinational population-based cohort study

Background

Escherichia coli is the most common cause of bloodstream infections (BSIs) and mortality is an important aspect of burden of disease. Using a multinational population-based cohort of E. coli BSIs, our objectives were to evaluate 30-day case fatality risk and mortality rate, and determine factors associated with each.

Methods

During 2014–2018, we identified 30-day deaths from all incident E. coli BSIs from surveillance nationally in Finland, and regionally in Sweden (Skaraborg) and Canada (Calgary, Sherbrooke, western interior). We used a multivariable logistic regression model to estimate factors associated with 30-day case fatality risk. The explanatory variables considered for inclusion were year (2014–2018), region (five areas), age (< 70-years-old, ≥70-years-old), sex (female, male), third-generation cephalosporin (3GC) resistance (susceptible, resistant), and location of onset (community-onset, hospital-onset). The European Union 28-country 2018 population was used to directly age and sex standardize mortality rates. We used a multivariable Poisson model to estimate factors associated with mortality rate, and year, region, age and sex were considered for inclusion.

Results

From 38.7 million person-years of surveillance, we identified 2961 30-day deaths in 30,923 incident E. coli BSIs. The overall 30-day case fatality risk was 9.6% (2961/30923). Calgary, Skaraborg, and western interior had significantly increased odds of 30-day mortality compared to Finland. Hospital-onset and 3GC-resistant E. coli BSIs had significantly increased odds of mortality compared to community-onset and 3GC-susceptible. The significant association between age and odds of mortality varied with sex, and contrasts were used to interpret this interaction relationship. The overall standardized 30-day mortality rate was 8.5 deaths/100,000 person-years. Sherbrooke had a significantly lower 30-day mortality rate compared to Finland. Patients that were either ≥70-years-old or male both experienced significantly higher mortality rates than those < 70-years-old or female.

Conclusions

In our study populations, region, age, and sex were significantly associated with both 30-day case fatality risk and mortality rate. Additionally, 3GC resistance and location of onset were significantly associated with 30-day case fatality risk. Escherichia coli BSIs caused a considerable burden of disease from 30-day mortality. When analyzing population-based mortality data, it is important to explore mortality through two lenses, mortality rate and case fatality risk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06326-x.

Mortality in Escherichia coli bloodstream infections: antibiotic resistance still does not make it

BACKGROUND

Escherichia coli bloodstream infections (BSIs) account for high mortality rates (5%-30%). Determinants of death are unclear, especially since the emergence of ESBL producers.

OBJECTIVES

To determine the relative weight of host characteristics, bacterial virulence and antibiotic resistance in the outcome of patients suffering from E. coli BSI.

METHODS

All consecutive patients suffering from E. coli BSI in seven teaching hospitals around Paris were prospectively included for 10 months. E. coli isolates were sequenced using Illumina NextSeq technology to determine the phylogroup, ST/ST complex (STc), virulence and antimicrobial resistance gene content. Risk factors associated with death at discharge or Day 28 were determined.

RESULTS

Overall, 545 patients (mean ± SD age 68.5 ± 16.5 years; 52.5% male) were included. Mean Charlson comorbidity index (CCI) was 5.6 (± 3.1); 19.6% and 12.8% presented with sepsis and septic shock, respectively. Portals of entry were mainly urinary (51.9%), digestive (41.9%) and pulmonary (3.5%); 98/545 isolates (18%) were third-generation cephalosporin resistant (3GC-R), including 86 ESBL producers. In-hospital death (or at Day 28) was 52/545 (9.5%). Factors independently associated with death were a pulmonary portal of entry [adjusted OR (aOR) 6.54, 95% CI 2.23-19.2, P = 0.0006], the iha_17 virulence gene (aOR 4.41, 95% CI 1.23-15.74, P = 0.022), the STc88 (aOR 3.62, 95% CI 1.30-10.09, P = 0.014), healthcare-associated infections (aOR 1.98, 95% CI 1.04-3.76, P = 0.036) and high CCI (aOR 1.14, 95% CI 1.04-1.26, P = 0.006), but not ESBL/3GC-R.

CONCLUSIONS

Host factors, portal of entry and bacterial characteristics remain major determinants associated with mortality in E. coli BSIs. Despite a high prevalence of ESBL producers, antibiotic resistance did not impact mortality. (ClinicalTrials.gov identifier: NCT02890901.).

Exploring antimicrobial resistance to beta-lactams, aminoglycosides and fluoroquinolones in E. coli and K. pneumoniae using proteogenomics

Antimicrobial resistance is mostly studied by means of phenotypic growth inhibition determinations, in combination with PCR confirmations or further characterization by means of whole genome sequencing (WGS). However, the actual proteins that cause resistance such as enzymes and a lack of porins cannot be detected by these methods. Improvements in liquid chromatography (LC) and mass spectrometry (MS) enabled easier and more comprehensive proteome analysis. In the current study, susceptibility testing, WGS and MS are combined into a multi-omics approach to analyze resistance against frequently used antibiotics within the beta-lactam, aminoglycoside and fluoroquinolone group in E. coli and K. pneumoniae. Our aim was to study which currently known mechanisms of resistance can be detected at the protein level using liquid chromatography-mass spectrometry (LC-MS/MS) and to assess whether these could explain beta-lactam, aminoglycoside, and fluoroquinolone resistance in the studied isolates. Furthermore, we aimed to identify significant protein to resistance correlations which have not yet been described before and to correlate the abundance of different porins in relation to resistance to different classes of antibiotics. Whole genome sequencing, high-resolution LC-MS/MS and antimicrobial susceptibility testing by broth microdilution were performed for 187 clinical E. coli and K. pneumoniae isolates. Resistance genes and proteins were identified using the Comprehensive Antibiotic Resistance Database (CARD). All proteins were annotated using the NCBI RefSeq database and Prokka. Proteins of small spectrum beta-lactamases, extended spectrum beta-lactamases, AmpC beta-lactamases, carbapenemases, and proteins of 16S ribosomal RNA methyltransferases and aminoglycoside acetyltransferases can be detected in E. coli and K. pneumoniae by LC-MS/MS. The detected mechanisms matched with the phenotype in the majority of isolates. Differences in the abundance and the primary structure of other proteins such as porins also correlated with resistance. LC-MS/MS is a different and complementary method which can be used to characterize antimicrobial resistance in detail as not only the primary resistance causing mechanisms are detected, but also secondary enhancing resistance mechanisms.

Decrease in All-Cause 30-Day Mortality after Bacteraemia over a 15-Year Period: A Population-Based Cohort Study in Denmark in 2000-2014

INTRODUCTION

Bacteraemia is a frequent infectious condition that strongly affects morbidity and mortality. The incidence is increasing worldwide. This study explores all-cause 30-day mortality after bacteraemia in two out of Denmark's five healthcare regions with approximately 2.4 million inhabitants.

METHODS

Clinically significant bacteraemia episodes (n = 55,257) were identified from a geographically well-defined background population between 2000 and 2014, drawing on population-based data regarding bacterial species and vital status. All-cause 30-day mortality was assessed in relation to bacteraemia episodes, number of patients with analysed blood cultures and the background population.

RESULTS

We observed a decreasing trend of all-cause 30-day mortality between 2000 and 2014, both in relation to the number of bacteraemia episodes and the background population. Mortality decreased from 22.7% of the bacteraemia episodes in 2000 to 17.4% in 2014 (annual IRR [95% CI]: 0.983 [0.979-0.987]). In relation to the background population, there were 41 deaths per 100,000 inhabitants in 2000, decreasing to 39 in 2014 (annual IRR [95% CI]: 0.988 [0.982-0.993]). Numbers of inhabitants, bacteraemia episodes, and analysed persons having BCs increased during the period.

CONCLUSIONS

All-cause 30-day mortality in patients with bacteraemia decreased significantly over a 15-year period.

Clinical Profile, Prognostic Factors, and Outcome Prediction in Hospitalized Patients With Bloodstream Infection: Results From a 10-Year Prospective Multicenter Study

Background: Bloodstream infection (BSI) is one of the most common serious bacterial infections worldwide and also a major contributor to in-hospital mortality. Determining the predictors of mortality is crucial for prevention and improving clinical prognosis in patients with nosocomial BSI. Methods: A nationwide prospective cohort study was conducted from 2007 until 2016 in 16 teaching hospitals across China. Microbiological results, clinical information, and patient outcomes were collected to investigate the pathogenic spectrum and mortality rate in patients with BSI and identify outcome predictors using multivariate regression, prediction model, and Kaplan-Meier analysis. Results: No significant change was observed in the causative pathogen distribution during the 10-year period and the overall in-hospital mortality was 12.83% (480/3,741). An increased trend was found in the mortality of patients infected with Pseudomonas aeruginosa or Acinetobacter baumannii, while a decreased mortality rate was noted in Staphylococcus aureus-related BSI. In multivariable-adjusted models, higher mortality rate was significantly associated with older age, cancer, sepsis diagnosis, ICU admission, and prolonged hospital stay prior to BSI onset, which were also determined using machine learning-based predictive model achieved by random forest algorithm with a satisfactory performance in outcome prediction. Conclusions: Our study described the clinical and microbiological characteristics and mortality predictive factors in patients with BSI. These informative predictors would inform clinical practice to adopt effective therapeutic strategies to improve patient outcomes.

Human carriage of cefotaxime-resistant Escherichia coli in North-East India: an analysis of STs and associated resistance mechanisms

OBJECTIVES

To determine the prevalence of Escherichia coli STs and associated resistance mechanisms carried by the community in North-East India.

METHODS

E. coli (108) were isolated from sewage collected from 19 sites across the city of Silchar by plating on MacConkey agar with/without selection (50 mg/L cefotaxime). Species identification was confirmed by MALDI-TOF MS for 82 isolates. Common resistance mechanisms were determined by WGS of pooled E. coli isolates. PFGE combined with specific probes determined the presence of common resistance mechanisms in all isolates. Phylotypes, multilocus STs, core-genome multilocus STs, resistance genes and virulence genes were determined by in silico analysis of 38 genomes.

RESULTS AND CONCLUSIONS

Analysis of isolates collected without selection (n=33) indicated that cefotaxime resistance in E. coli was 42% (14/33) and estimated meropenem resistance at 9%. The remaining 58% (19/33) were additionally susceptible to ampicillin, trimethoprim, ciprofloxacin and aminoglycosides. The most common ST among the cefotaxime-resistant E. coli was ST167 (29%), followed by ST410 (17%) and ST648 (10%). E. coli ST131 was absent from the collection. Sixty-three isolates were resistant to cefotaxime and harboured blaCTX-M-15 [54% (34/63)] or blaCMY-42 [46% (29/63)], of which 10% (6/63) harboured both genes. Carbapenem resistance was due to blaNDM-5, found in 10/63 cefotaxime-resistant isolates, and/or blaOXA-181, found in 4/63 isolates. NDM-5 was encoded by IncX3 and/or IncFII plasmids and CMY-42 was mostly encoded by IncI plasmids. NDM-5 appears to have replaced NDM-1 in this region and CMY-42 appears to be in the process of replacing CTX-M-15.

Myristic Acid Serum Levels and Their Significance for Diagnosis of Systemic Inflammatory Response, Sepsis, and Bacteraemia

Myristic acid is identified as a metabolite with the highest diagnostic sensitivity and specificity in the metabolome of patients with bacteraemia. Its significant decrease has been observed in patients with septic shock not responding to treatment. Another study has reported a close correlation of myristic acid levels with the outcome of severe trauma patients. Myristic acid concentrations were investigated in a cohort of septic patients and patients with Systemic Inflammatory Response Syndrome (SIRS) in 5 consecutive days following diagnosis and compared to healthy controls. The study population groups-Sepsis 34, SIRS 31, and Healthy Control 120 patients were included. Serum samples were analyzed using gas chromatography and mass spectrometry. The myristic acid levels in the Sepsis Group and SIRS Group were found to be significantly higher when compared to healthy controls. The serum concentration of myristic acid in septic patients with bacteraemia was higher than in septic patients without bacteraemia. Most patients with sepsis and SIRS had the highest levels of myristic acid within 24 h after an established diagnosis. Myristic acid should be considered as a new candidate marker of severe inflammation and sepsis. A simplified analysis and sufficient body of validated data are necessary steps towards the introduction of this metabolite into routine clinical practice.

Prevalence and Antibiotic Resistance Characteristics of Extraintestinal Pathogenic Escherichia coli among Healthy Chickens from Farms and Live Poultry Markets in China

Simple Summary

Chicken meat has been proved to be a suspected source of extraintestinal pathogenic Escherichia coli (ExPEC), causing several diseases in humans, and bacteria in healthy chickens can contaminate chicken carcasses at the slaughter; however, reports about the prevalence and molecular characteristics of ExPEC in healthy chickens are still rare. In this study, among 926 E. coli isolates from healthy chickens in China, 22 (2.4%) were qualified as ExPEC and these ExPEC isolates were clonally unrelated. A total of six serogroups were identified in this study, with O78 being the most predominant type, and all the six serogroups had been frequently reported in human ExPEC isolates in many countries. All the 22 ExPEC isolates were multidrug-resistant and most isolates carried both bla_CTX-M and fosA3 resistance genes. Notably, plasmid-borne colistin resistance gene mcr-1 was identified in six ExPEC isolates, among which two carried additional carbapenemase gene bla_NDM, compromising both the efficacies of the two critically important drugs for humans, carbapenems and colistin. These results highlight that healthy chickens can serve as a potential reservoir for multidrug resistant ExPEC isolates, including mcr-1-containing ExPEC.

Abstract

Chicken products and chickens with colibacillosis are often reported to be a suspected source of extraintestinal pathogenic Escherichia coli (ExPEC) causing several diseases in humans. Such pathogens in healthy chickens can also contaminate chicken carcasses at the slaughter and then are transmitted to humans via food supply; however, reports about the ExPEC in healthy chickens are still rare. In this study, we determined the prevalence and characteristics of ExPEC isolates in healthy chickens in China. A total of 926 E. coli isolates from seven layer farms (371 isolates), one white-feather broiler farm (78 isolates) and 17 live poultry markets (477 isolates from yellow-feather broilers) in 10 cities in China, were isolated and analyzed for antibiotic resistance phenotypes and genotypes. The molecular detection of ExPEC among these healthy chicken E. coli isolates was performed by PCRs, and the serogroups and antibiotic resistance characteristics of ExPEC were also analyzed. Pulsed-field gel electrophoresis (PFGE) and Multilocus sequence typing (MLST) were used to analyze the genetic relatedness of these ExPEC isolates. We found that the resistance rate for each of the 15 antimicrobials tested among E. coli from white-feather broilers was significantly higher than that from brown-egg layers and that from yellow-feather broilers in live poultry markets (p < 0.05). A total of 22 of the 926 E. coli isolates (2.4%) from healthy chickens were qualified as ExPEC, and the detection rate (7.7%, 6/78) of ExPEC among white-feather broilers was significantly higher than that (1.6%, 6/371) from brown-egg layers and that (2.1%, 10/477) from yellow-feather broilers (p < 0.05). PFGE and MLST analysis indicated that clonal dissemination of these ExPEC isolates was unlikely. Serogroup O78 was the most predominant type among the six serogroups identified in this study, and all the six serogroups had been frequently reported in human ExPEC isolates in many countries. All the 22 ExPEC isolates were multidrug-resistant (MDR) and the resistance rates to ampicillin (100%) and sulfamethoxazole-trimethoprim (100%) were the highest, followed by tetracycline (95.5%) and doxycycline (90.9%). bla_CTX-M was found in 15 of the 22 ExPEC isolates including 10 harboring additional fosfomycin resistance gene fosA3. Notably, plasmid-borne colistin resistance gene mcr-1 was identified in six ExPEC isolates in this study. Worryingly, two ExPEC isolates were found to carry both mcr-1 and bla_NDM, compromising both the efficacies of carbapenems and colistin. The presence of ExPEC isolates in healthy chickens, especially those carrying mcr-1 and/or bla_NDM, is alarming and will pose a threat to the health of consumers. To our knowledge, this is the first report of mcr-1-positive ExPEC isolates harboring bla_NDM from healthy chickens.

Early prediction of blood stream infection in a prospectively collected cohort

Background

Blood stream infection (BSI) and sepsis are serious clinical conditions and identification of the disease-causing pathogen is important for patient management. The RISE (Rapid Identification of SEpsis) study was carried out to collect a cohort allowing high-quality studies on different aspects of BSI and sepsis. The aim of this study was to identify patients at high risk for BSI who might benefit most from new, faster, etiological testing using neutrophil to lymphocyte count ratio (NLCR) and Shapiro score.

Methods

Adult patients (≥ 18 years) presenting at the emergency department (ED) with suspected BSI were prospectively included between 2014 and 2016 at Örebro University Hospital. Besides extra blood sampling, all study patients were treated according to ED routines. Electronic patient charts were retrospectively reviewed. A modified Shapiro score (MSS) and NLCR were extracted and compiled. Continuous score variables were analysed with area under receiver operator characteristics curves (AUC) to evaluate the ability of BSI prediction.

Results

The final cohort consisted of 484 patients where 84 (17%) had positive blood culture judged clinically significant. At optimal cut-offs, MSS (≥3 points) and NLCR (> 12) showed equal ability to predict BSI in the whole cohort (AUC 0.71/0.74; sensitivity 69%/67%; specificity 64%/68% respectively) and in a subgroup of 155 patients fulfilling Sepsis-3 criteria (AUC 0.71/0.66; sensitivity 81%/65%; specificity 46%/57% respectively). In BSI cases only predicted by NLCR> 12 the abundance of Gram-negative to Gram-positive pathogens (n = 13 to n = 4) differed significantly from those only predicted by MSS ≥3 p (n = 7 to n = 12 respectively) (p < 0.05).

Conclusions

MSS and NLCR predicted BSI in the RISE cohort with similar cut-offs as shown in previous studies. Combining the MSS and NLCR did not increase the predictive performance. Differences in BSI prediction between MSS and NLCR regarding etiology need further evaluation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-05990-3.

Correlations of Host and Bacterial Characteristics with Clinical Parameters and Survival in Staphylococcus aureus Bacteremia

Staphylococcus aureus bacteremia (SAB) is a frequent, severe condition that occurs in patients of all age groups and affects clinical departments of all medical fields. It is associated with a high mortality rate of 20-30%. In this study, we analyzed patient mortality associated with SAB at our tertiary care university hospital, assessed the clinical management in terms of administered antimicrobial therapy, and determined which factors have an impact on the clinical course and outcome of patients with this disease. We collected clinical data and blood culture isolates of 178 patients diagnosed with SAB between May 2013 and July 2015. For this study, bacteria were cultured and analyzed concerning their phenotype, hemolysis activity, biofilm formation, nuclease activity, prevalence of toxin genes, spa and agr type. Overall mortality was 24.2% and 30-day mortality was 14.6%. Inadequate initial therapy was administered to 26.2% of patients and was associated with decreased survival (p = 0.041). Other factors associated with poor survival were patient age (p = 0.003), agr type 4 (p ≤ 0.001) and pathological leukocyte counts (p = 0.029 if elevated and p = 0.003 if lowered). The type of infection focus, spa clonal complex and enterotoxin genes seg and sei had an impact on severity of inflammation. Our results indicate that mortality and burden of disease posed by SAB are high at our university hospital.

Bacterial virulence plays a crucial role in MRSA sepsis

Bacterial sepsis is a major global cause of death. However, the pathophysiology of sepsis has remained poorly understood. In industrialized nations, Staphylococcus aureus represents the pathogen most commonly associated with mortality due to sepsis. Because of the alarming spread of antibiotic resistance, anti-virulence strategies are often proposed to treat staphylococcal sepsis. However, we do not yet completely understand if and how bacterial virulence contributes to sepsis, which is vital for a thorough assessment of such strategies. We here examined the role of virulence and quorum-sensing regulation in mouse and rabbit models of sepsis caused by methicillin-resistant S. aureus (MRSA). We determined that leukopenia was a predictor of disease outcome during an early critical stage of sepsis. Furthermore, in device-associated infection as the most frequent type of staphylococcal blood infection, quorum-sensing deficiency resulted in significantly higher mortality. Our findings give important guidance regarding anti-virulence drug development strategies for the treatment of staphylococcal sepsis. Moreover, they considerably add to our understanding of how bacterial sepsis develops by revealing a critical early stage of infection during which the battle between bacteria and leukocytes determines sepsis outcome. While sepsis has traditionally been attributed mainly to host factors, our study highlights a key role of the invading pathogen and its virulence mechanisms.

Association between high vancomycin minimum inhibitory concentration and clinical outcomes in patients with methicillin-resistant Staphylococcus aureus bacteraemia - A retrospective cohort study

The purpose of this study is to determine the role of high (≥ 1.5 mg/L) vancomycin minimum inhibitory concentration (VMIC) in predicting clinical outcomes in patients with methicillin-resistant Staphylococcus aureus bacteraemia (MRSAB). A retrospective study was conducted at Mayo Clinic, Minnesota. Patients ≥ 18 years with a 3-month follow-up were included. Outcomes were defined as 30-day all-cause in-hospital mortality, median duration of bacteraemia, metastatic infectious complications, and relapse of MRSAB. A total of 475 patients with MRSAB were identified, and 93 (19.6%) of them had high VMIC isolates. Sixty-four percent of patients were male with a mean age of 69.0 years. Active solid organ malignancy and skin and soft tissue infection as source of MRSAB were associated with high VMIC, while septic arthritis as a complication was significantly associated with low VMIC on multivariate analysis. Eighty-one (17.1%) patients died within 30 days of hospitalization, with no significant difference in mortality rates between the two groups. In-hospital mortality, median duration of bacteraemia, and metastatic infectious complications were not significantly associated with high VMIC MRSAB.

Burden of bloodstream infection in older persons: a population-based study

BACKGROUND

Advancing age is a major risk factor for developing and dying from bloodstream infections (BSI). However, there is a paucity of population-based studies investigating the epidemiology of BSI in older persons.

OBJECTIVE

To define the incidence, clinical determinants, and risk factors for death among those aged 65 years and older with BSI.

METHODS

Population-based surveillance was conducted in the western interior of British Columbia, Canada, between April 1, 2010 and March 31, 2020. Chart reviews were conducted for clinical details and all cause case-fatality was established at 30-days follow-up.

RESULTS

A total of 1854 incident BSI were identified among 1657 individuals aged 65 and older for an annual incidence of 533.9 per 100,000 population; the incidence for those aged 65-74, 75-84, and ≥85 years was 375.3, 678.9, and 1046.6 per 100,000 population, respectively. Males were at significantly increased risk as compared to females (incidence rate ratio, IRR 1.44; 95% confidence interval, CI, 1.32-1.59; p<0.0001). The crude annual incidence increased by 50% during the study. However, this was related to shift in population demographics with no increase evident following age- and sex-standardization. Older patients were more likely to have healthcare-associated infections and genitourinary sources and less likely to have bone/joint or soft tissue infections. The proportion of patients with underlying congestive heart failure, stroke, and dementia increased, whereas diabetes and liver disease decreased with older age. The overall 30-day all cause case-fatality rate was 22.0% (364/1657). After adjustment for clinical focus, onset of infection, etiology, and co-morbidity in a logistic model, those aged 75-84 years (odds ratio, OR, 1.66; 95% CI, 1.25-2.21) and ≥ 85 years (OR, 1.98; 95% CI, 1.41-2.77) were at significantly increased risk for death as compared to those aged 65-74 years.

CONCLUSION

Bloodstream infection is common in older persons and is a major cause of death. Countries with aging populations worldwide should expect an increase burden associated with BSI in the coming years.

Prognostic value of central venous-to-arterial carbon dioxide difference in patients with bloodstream infection

Background: Bloodstream infection (BSI) are prone to circulation disorders, which portend poor outcome. The central venous-to-arterial carbon dioxide difference (Pcv-aCO₂) is a biomarker for circulation disorders, but the prognostic value of Pcv-aCO₂ in BSI patients remains unclear. This study was to investigate the association of Pcv-aCO₂ with adverse events in BSI patients. Methods: The patients with BSI between August 2014 and August 2017 were prospectively enrolled. Clinical characteristic and laboratory results were collected. We analyzed the association of the level of Pcv-aCO₂ with clinical variables and 28-day mortality. Results: A total of 152 patients were enrolled. The Pcv-aCO₂ was positively correlated with white blood cell count (r=0.241, p=0.003), procalcitonin (r=0.471, p<0.001), C-reactive protein (r=0.192, p=0.018), lactate (r=0.179, p=0.027), Sequential Organ Failure Assessment (r=0.318, p<0.001) and Acute Physiology And Chronic Health Evaluation II score (r=0.377, p<0.001), while that was negatively correlated with central venous oxygen saturation (r=-0.242, p<0.001) and platelet (r=-0.205, p=0.011). Kaplan-Meier curves demonstrated that patients with Pcv-aCO₂ >6mmHg had a worse prognosis than those without (log rank=32.10, p<0.001). Multivariate analysis showed Level of Pcv-aCO₂ was an independent risk factor for 28-day mortality (HR: 3.10, 95% CI: 1.43-6.74, p=0.004). The area under the receiver operating characteristic curve of Pcv-aCO₂ for prediction of 28-day mortality in patients with BSI was 0.794. Pcv-aCO₂>6 mmHg had 81.1% sensitivity and 78.8% specificity for predicting 28-day mortality. Conclusion: Pcv-aCO₂ may be a simple and valuable biomarker to assessment of 28-day mortality in patients with BSI.

Evaluation of Rapid Sepsityper® protocol and specific MBT-Sepsityper module (Bruker Daltonics) for the rapid diagnosis of bacteremia and fungemia by MALDI-TOF-MS

During bloodstream infections, rapid adaptation of empirical treatment according to the microorganism identified is essential to decrease mortality. The aim of the present study was to assess the microbiological performances of a new rapid version of the Sepsityper® kit (Bruker Daltonics) allowing identification of bacteria and yeast by MALDI-TOF mass spectrometry directly from positive blood cultures in 10 min and of the specific MBT-Sepsityper module for spectra analysis, designed to increase identification performance. Identification rates were determined prospectively on 350 bacterial and 29 fungal positive blood cultures, and compared to conventional diagnostic method. Our rapid diagnosis strategy (Rapid Sepsityper® protocol: one spot with and one without formic acid extraction step) combined to MBT-Sepsityper module provided 65.4%, 78.9% and 62% reliable identification to the species level of monomicrobial positive blood cultures growing respectively Gram-positive, Gram-negative bacteria or yeast. Importantly, identification rates of Gram-positive bacteria were higher in anaerobic than in aerobic bottles (77.8% vs 22.2%; p = 0.004), if formic acid extraction step was performed (60.8% vs 39.2%; p = 1.8e⁻⁶) and if specific MBT-Sepsityper module was used (76.2% vs 61.9%, p = 0.041) while no significant differences were observed for Gram-negative bacteria. For yeasts identification, formic acid extraction step improved rapid identification rate by 37.9% while the specific MBT-Sepsityper module increased overall performances by 38%, providing up to 89.7% reliable identification if associated with the standard Sepsityper® protocol. These performances, associated with a reduce turnaround time, may help to implement a rapid identification strategy of bloodstream infections in the routine workflow of microbiology laboratories.

In-house protocol and performance of MALDI-TOF MS in the early diagnosis of bloodstream infections in a fourth-level hospital in Colombia: Jumping to full use of this technology

BACKGROUND

Bloodstream infections (BSIs) are a major cause of mortality in hospitalized patients. Rapid diagnosis is crucial because any delay in the antimicrobial treatment is associated with an increase in adverse patient outcomes. The application of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) technology directly to blood cultures permits earlier identification of BSIs and facilitates treatment management.

METHODS

A total of 470 positive blood cultures from patient samples were analyzed using Standard Aerobic/F and Anaerobic/F blood culture media. Isolates were identified using conventional identification methods and by the direct method using the MALDI-TOF MS system.

RESULTS

In 470 blood cultures, the direct method showed good identification results (420/470, 89%); specifically, accurate species and genus identification in 283/470 (60%), and only correct genus identification in 137/470 (29%). The direct protocol had better performance for Gram-negative compared to Gram-positive bacteria (97% vs 76%) and was unable to identify the positive blood cultures for both yeasts and some bacteria, mostly Gram-positive (50/470).

CONCLUSIONS

The protocol used here gave good and reliable results, being available up to 24 h earlier, while also leading to better use of MALDI-TOF.

In Vitro Activity and Potency of the Novel Oxazolidinone Contezolid (MRX-I) Tested against Gram-Positive Clinical Isolates from the United States and Europe

Contezolid, a new oxazolidinone antibacterial agent currently in development for the treatment of skin and skin structure infections, was susceptibility tested against Gram-positive clinical isolates (n = 1,211). Contezolid demonstrated potent activity against Staphylococcus aureus (MIC_50/90, 0.5/1 mg/liter), coagulase-negative Staphylococcus (MIC_50/90, 0.25/0.5 mg/liter), Enterococcus spp. (MIC_50/90, 0.5/1 mg/liter), and streptococci (MIC_50/90, 1/1 mg/liter). Moreover, methicillin-resistant S. aureus and vancomycin-resistant Enterococcus faecium isolates were all inhibited by contezolid at ≤1 mg/liter. These results support the clinical development of contezolid.

Rapid method for direct identification of positive blood cultures by MALDI-TOF MS

Application of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) using positive blood cultures (BCs) is a revolution in identification of microorganisms in clinical microbiology laboratories. Although there are several commercial pretreatment protocols they are expensive. Here, we evaluated the performance of a locally produced Bioyong pre-treatment kit for the direct identification of microorganisms in positive BCs by MALDI-TOF MS method. The mocked positive BCs were performed using 200 Thermo aerobic blood culture bottles and 200 aerobic Scenker blood culture bottles. A total of 200 organisms were invovled, including 91 strains of Gram-positive bacteria, 97 strains of Gram-negative bacteria and 12 strains of Candida. The positive BCs were subcultured and identified by classical biochemical Vitek II testing as the gold standard of identification. The Bioyong pre-treatment kit could successfully identify microorganisms in 189 (94.5%) Thermo positive BCs and 189 (94.5%) Scenker positive blood cultures, respectively. In total, 94 (96.9%) Gram-negative bacteria, 86 (94.5%) Gram-positive bacteria and 9 (75.0%) candida isolated from Thermo positive BCs were correctly identified to species level and 95 (97.9%) Gram-negative bacteria, 86 (94.5%) Gram-positive bacteria and 8 (66.7%) candida isolated from Scenker positive BCs were correctly identified to species level. This method provides a rapid, accurate identification of bacteria and Candida within one hour in positive blood cultures. Routine application of this technique will improve the antimicrobial treatment within 24 h among the patients with bacteremia and candidemia.

Blood urea nitrogen to serum albumin ratio independently predicts 30-day mortality and severity in patients with Escherichia coli bacteraemia

BACKGROUND

Elevated blood urea nitrogen to serum albumin (BUN/ALB) ratio had been identified as an independent risk factor related to mortality in community-acquired and hospital-acquired pneumonia. This study aimed to investigate whether this clinical index can predict the clinical outcomes of E. coli bacteraemia.

MATERIAL AND METHODS

Clinical data were collected from patients with E. coli bacteraemia attended at our hospital between January 2012 and December 2018. The endpoints were mortality within 30 days after the diagnosis of E. coli bacteraemia and intensive care (IC) requirement. Cox regression analysis was performed to evaluate the risk factors.

RESULTS

A total of 398 patients with E. coli bacteraemia were enrolled in this study and 56 patients died within 30 days after bacteraemia onset. Multivariate Cox regression analysis showed that age greater than 65 years, lymphocyte count<.8×10e9/L, elevated BUN/ALB ratio, increased SOFA score, carbapenem resistance, central venous catheterization before onset of bacteraemia, and infection originating from abdominal cavity were independent risk factors for 30-day mortality (P<.05). The risk factors associated with IC requirement were similar to those for 30-day mortality except central venous catheterization before onset of bacteraemia. The area under the receiver-operating characteristic curve for BUN/ALB ratio predicting 30-day mortality and IC requirement was similar to that for SOFA score, but higher than that for lymphocyte count. The cut-off points of BUN/ALB ratio to predict 30-day mortality and IC requirement were both .3.

CONCLUSIONS

BUN/ALB ratio is a simple but independent predictor of 30-day mortality and severity in E. coli bacteraemia. A higher BUN/ALB ratio at the onset of bacteraemia predicts a higher mortality rate and IC requirement.

The burden of bacteremic and non-bacteremic Gram-negative infections: A prospective multicenter cohort study in a low-resistance country

Objectives There is a global increase in infections caused by Gram-negative bacteria. The majority of research is on bacteremic Gram-negative infections (GNI), leaving a knowledge gap on the burden of non-bacteremic GNI. Our aim is to describe characteristics and determine the burden of bacteremic and non-bacteremic GNI in hospitalized patients in the Netherlands. Methods We conducted a prospective cohort study of patients in eight hospitals with microbiologically confirmed GNI, between June 2013 and November 2015. In each hospital the first five adults meeting the eligibility criteria per week were enrolled. We estimated the national incidence and mortality of GNI by combining the cohort data with a national surveillance database for antimicrobial resistance. Results 1,954 patients with GNI were included of which 758 (39%) were bloodstream infections (BSI). 243 GNI (12%) involved multi-drug resistant pathogens. 30-day mortality rate was 11.1% (n = 217) Estimated national incidences of non-bacteremic GNI and bacteremic GNI in hospitalized adults were 74 (95% CI 58 - 89) and 86 (95% CI 72-100) per 100,000 person years, yielding estimated annual numbers of 30-day all-cause mortality deaths of 1,528 (95% CI 1,102-1,954) for bacteremic and 982 (95% CI 688 - 1,276) for non-bacteremic GNI. Conclusion GNI form a large mortality burden in a low-resistance country. A third of the associated mortality occurs after non-bacteremic GNI.