Risk Factors for Recurrent Staphylococcus aureus Bacteremia

Persistent Gram-negative Bloodstream Infection Increases the Risk of Recurrent Bloodstream Infection With the Same Species

The association between persistent gram-negative bloodstream infection (GN-BSI), or ongoing positive cultures, and recurrent GN-BSI has not been investigated. Among 992 adults, persistent GN-BSI was associated with increased recurrent GN-BSI with the same bacterial species and strain (6% vs 2%; P = .04). Persistent GN-BSI may be a marker of complicated infection.

Performance of Risk Scores in Predicting Infective Endocarditis in Patients with Staphylococcus aureus Bacteraemia in a Prospective Asian Cohort

Background: Several risk scores have been derived to predict the risk of infective endocarditis (IE) amongst patients with Staphylococcus aureus bacteraemia (SAB), which helps to guide clinical management. Methods: We prospectively studied 634 patients admitted with SAB. The cohort was stratified into those with or without IE, and the PREDICT Day 1, Day 5 and VIRSTA scores were tabulated. Area under the receiver operating characteristic (AUC) curves were constructed to compare the performance of each score. Results: Of the 634 patients examined, 36 (5.7%) had IE. These patients were younger (51.6 ± 20.1 vs. 59.2 ± 18.0 years, p = 0.015), tended to have community acquisition of bacteraemia (41.7% vs. 17.9%, p < 0.001), and had persistent bacteraemia beyond 72 h (19.4% vs. 6.0%, p = 0.002). The VIRSTA score had the best performance in predicting IE (AUC 0.76, 95%CI 0.66-0.86) compared with PREDICT Day 1 and Day 5. A VIRSTA score of <3 had the best negative predictive value (97.5%), compared with PREDICT Day 1 (<4) and Day 5 (<2) (94.3% and 96.6%, respectively). Conclusions: Overall, the risk scores performed well in our Asian cohort. If applied, 23.5% of the cohort with a VIRSTA ≥ 3 would require TEE, and a score of <3 had an excellent negative predictive value.

Use of Transcriptional Signatures to Differentiate Pathogen-Specific and Treatment-Specific Host Responses in Patients With Bacterial Bloodstream Infections

BACKGROUND

Clinical outcomes in bacterial bloodstream infections (BSIs) are influenced by bacterial species, host immunity, and antibiotic therapy. The mechanisms by which such factors influence outcomes are poorly understood. We aimed to identify bacterial- and antibiotic-specific host transcriptional signatures in patients with bacterial BSI.

METHODS

RNA sequencing was performed on blood samples from patients with BSI due to gram-negative (GN) versus gram-positive (GP) pathogens: Escherichia coli (n = 30) or Klebsiella pneumoniae (n = 28) versus methicillin-susceptible Staphylococcus aureus (MSSA) (n = 24) or methicillin-resistant S. aureus (MRSA) (n = 58). Patients were matched by age, sex, and race.

RESULTS

No significant host transcriptome differences were detected in patients with E. coli versus K. pneumoniae BSI, so these were considered together as GN BSI. Relative to S. aureus BSI, patients with GN BSI had increased activation of the classic complement system. However, the most significant signal was a reduction in host transcriptional signatures involving mitochondrial energy transduction and oxidative burst in MRSA versus MSSA. This attenuated host transcriptional signature remained after controlling for antibiotic therapy.

CONCLUSIONS

Given the importance of immune cellular energetics and reactive oxygen species in eliminating hematogenous or intracellular MRSA, these findings may offer insights into its persistence relative to other bacterial BSIs.

Antimicrobial Resistance as Risk Factor for Recurrent Bacteremia after Staphylococcus aureus, Escherichia coli, or Klebsiella spp. Community-Onset Bacteremia

We investigated links between antimicrobial resistance in community-onset bacteremia and 1-year bacteremia recurrence by using the clinical data warehouse of Europe's largest university hospital group in France. We included adult patients hospitalized with an incident community-onset Staphylococcus aureus, Escherichia coli, or Klebsiella spp. bacteremia during 2017-2019. We assessed risk factors of 1-year recurrence using Fine-Gray regression models. Of the 3,617 patients included, 291 (8.0%) had >1 recurrence episode. Third-generation cephalosporin (3GC)-resistance was significantly associated with increased recurrence risk after incident Klebsiella spp. (hazard ratio 3.91 [95% CI 2.32-6.59]) or E. coli (hazard ratio 2.35 [95% CI 1.50-3.68]) bacteremia. Methicillin resistance in S. aureus bacteremia had no effect on recurrence risk. Although several underlying conditions and infection sources increased recurrence risk, 3GC-resistant Klebsiella spp. was associated with the greatest increase. These results demonstrate a new facet to illness induced by 3GC-resistant Klebsiella spp. and E. coli in the community setting.

The association of female sex with management and mortality in patients with Staphylococcus aureus bacteraemia

OBJECTIVES

The association of biological female sex with outcome in patients with Staphylococcus aureus bacteraemia remains unresolved. The aim of this study was to determine the independent association of female sex with management and mortality in patients with S. aureus bacteraemia.

METHODS

This is a post hoc analysis of prospectively collected data from the S. aureus Bacteraemia Group Prospective Cohort Study. Adult patients with monomicrobial S. aureus bacteraemia at Duke University Medical Center were enrolled from 1994 to 2020. Univariable and multivariable Cox regression analyses were performed to assess differences in management and mortality between females and males.

RESULTS

Among 3384 patients with S. aureus bacteraemia, 1431 (42%) were women. Women were, as compared with men, more often Black (581/1431 [41%] vs. 620/1953 [32%], p < 0.001), haemodialysis dependent (309/1424 [22%] vs. 334/1940 [17%], p 0.001) and more likely to be infected with methicillin-resistant S. aureus (MRSA) (697/1410 [49%] MRSA in women vs. 840/1925 [44%] MRSA in men, p 0.001). Women received shorter durations of antimicrobial treatment (median 24 [interquartile range 14-42] vs. 28 [interquartile range 14-45] days, p 0.005), and were less likely to undergo transesophageal echocardiography as compared with men (495/1430 [35%] vs. 802/1952 [41%], p < 0.001). Despite these differences, female sex was not associated with 90-day mortality in either univariable (388/1431 [27%] in women vs. 491/1953 [25%] in men, p 0.204) or multivariable analysis (adjusted hazard ratio for women 0.98 [95% CI, 0.85-1.13]).

DISCUSSION

Despite significant differences in patient characteristics, disease characteristics, and management, women and men with S. aureus bacteraemia have a similar mortality risk.

Increasing numbers and complexity of Staphylococcus aureus bloodstream infection-14 years of prospective evaluation at a German tertiary care centre with multi-centre validation of findings

OBJECTIVES

Staphylococcus aureus bloodstream infection (SAB) is a common and severe infection. This study aims to describe temporal trends in numbers, epidemiological characteristics, clinical manifestations, and outcomes of SAB.

METHODS

We performed a post-hoc analysis of three prospective SAB cohorts at the University Medical Centre Freiburg between 2006 and 2019. We validated our findings in a large German multi-centre cohort of five tertiary care centres (R-Net consortium, 2017-2019). Time-dependent trends were estimated using Poisson or beta regression models.

RESULTS

We included 1797 patients in the mono-centric and 2336 patients in the multi-centric analysis. Overall, we observed an increasing number of SAB cases over 14 years (6.4%/year and 1000 patient days, 95% CI: 5.1% to 7.7%), paralleled by an increase in the proportion of community-acquired SAB (4.9%/year [95% CI: 2.1% to 7.8%]) and a decrease in the rate of methicillin-resistant-SAB (-8.5%/year [95% CI: -11.2% to -5.6%]). All of these findings were confirmed in the multi-centre validation cohort (6.2% cases per 1000 patient cases/year [95% CI: -0.6% to 12.6%], community-acquired-SAB 8.7% [95% CI: -1.2% to 19.6%], methicillin-resistant S. aureus-SAB -18.6% [95% CI: -30.6 to -5.8%]). Moreover, we found an increasing proportion of patients with multiple risk factors for complicated/difficult-to-treat SAB (8.5%/year, 95% CI: 3.6% to 13.5%, p < 0.001), alongside an overall higher level of comorbidities (Charlson comorbidity score 0.23 points/year, 95% CI: 0.09 to 0.37, p 0.005). At the same time, the rate of deep-seated foci such as osteomyelitis or deep-seated abscesses significantly increased (6.7%, 95% CI: 3.9% to 9.6%, p < 0.001). A reduction of in-hospital mortality by 0.6% per year (95% CI: 0.08% to 1%) was observed in the subgroup of patients with infectious diseases consultations.

DISCUSSION

We found an increasing number of SAB combined with a significant increase in comorbidities and complicating factors in tertiary care centres. The resulting challenges in securing adequate SAB management in the face of high patient turnover will become an important task for physicians.

Transcatheter Aortic Valve Replacement for Aortic Valve Infective Endocarditis: A Systematic Review and Call for Action

We aimed to systematically analyze the literature on the use of transcatheter aortic valve replacement (TAVR) to treat active aortic valve infective endocarditis (AV-IE). Surgery is declined in one-third of patients with IE who meet indications because of prohibitive surgical risk. TAVR might be an alternative for selected patients with AV-IE as a bridge-to-surgery or stand-alone therapy. PubMed/MEDLINE, Embase, and Cochrane databases were searched (2002-2022) for studies on TAVR use in active AV-IE. Of 450 identified reports, six met inclusion criteria (all men, mean age 71 ± 12 years, median Society of Thoracic Surgeons (STS) score 27, EuroSCORE 56). All patients were prohibitive surgical risk candidates. Five out of six patients had severe, and one patient had moderate aortic regurgitation on presentation. Five out of six patients had prosthetic valve endocarditis after surgical valve replacement 13 years before (median), and one patient had TAVR a year before hospitalization. All patients had cardiogenic shock as the indication for TAVR. Four patients received balloon-expanding, and two patients received self-expanding TAVR after a median of 19 (IQR 9-25) days from diagnosis of IE. No death or myocardial infarction occurred, but one patient had a stroke within the first 30 days. The median event-free time was 9 (IQR 6-14) months including no death, reinfection, relapse IE, or valve-related rehospitalization. Our review suggests that TAVR can be considered as an adjuvant therapy to medical treatment for selected patients in whom surgery is indicated for treatment of acute heart failure due to aortic valve destruction and incompetence caused by infective endocarditis, but who have a prohibitive surgical risk. Nonetheless, a well-designed prospective registry is urgently needed to investigate the outcomes of TAVR for this off-label indication. No evidence exists for using the TAVR to treat infection-related surgical indications such as uncontrolled infection or control of septic embolization.

Black and White Patients With Staphylococcus aureus Bacteremia Have Similar Outcomes but Different Risk Factors

BACKGROUND

Staphylococcus aureus bacteremia (SAB) disproportionately affects Black patients. The reasons for this disparity are unclear.

METHODS

We evaluated a prospectively ascertained cohort of patients with SAB from 1995 to 2020. Clinical characteristics, bacterial genotypes, and outcome were compared among Black and White patients with SAB. Multivariable logistic regression models were used to determine factors independently associated with the outcomes.

RESULTS

Among 3068 patients with SAB, 1107 (36%) were Black. Black patients were younger (median, 56 years vs 63 years; P < .001) and had higher rates of diabetes (47.5% vs 34.5%, P < .001), hemodialysis dependence (40.0% vs 7.3%, P < .001), and human immunodeficiency virus (6.4% vs 0.6%, P < .001). Black patients had higher rates of methicillin-resistant S. aureus (49.3% vs 44.9%, P = .020), including the USA300 hypervirulent clone (11.5% vs 8.4%, P = .007). White patients had higher rates of corticosteroid use (22.4% vs 15.8%, P < .0001) and surgery in the preceding 30 days (28.1% vs 18.7%, P < .001). Although the median Acute Physiology Score (APS) at the time of initial SAB diagnosis was significantly higher in Black patients (median APS, 9; interquartile range [IQR], 5-14 vs median APS, 7; IQR, 4-12; P < .001), race was not associated with 90-day mortality (risk ratio, 1.02; 95% confidence interval, .93-1.12), and rates of metastatic infection were lower among Black patients (37.2% vs 41.3% White, P = .029).

CONCLUSIONS

Despite differences in Black patients' higher APS on presentation and more risk factors, including a 5 times higher risk of hemodialysis dependence, 90-day mortality among Black and White patients with SAB was similar.

XerC Is Required for the Repair of Antibiotic- and Immune-Mediated DNA Damage in Staphylococcus aureus

To survive in the host environment, pathogenic bacteria need to be able to repair DNA damage caused by both antibiotics and the immune system. The SOS response is a key bacterial pathway to repair DNA double-strand breaks and may therefore be a good target for novel therapeutics to sensitize bacteria to antibiotics and the immune response. However, the genes required for the SOS response in Staphylococcus aureus have not been fully established. Therefore, we carried out a screen of mutants involved in various DNA repair pathways to understand which were required for induction of the SOS response. This led to the identification of 16 genes that may play a role in SOS response induction and, of these, 3 that affected the susceptibility of S. aureus to ciprofloxacin. Further characterization revealed that, in addition to ciprofloxacin, loss of the tyrosine recombinase XerC increased the susceptibility of S. aureus to various classes of antibiotics, as well as to host immune defenses. Therefore, the inhibition of XerC may be a viable therapeutic approach to sensitize S. aureus to both antibiotics and the immune response.

Propensity-matched analysis of the protective effect of ticagrelor versus clopidogrel on the risk of developing Staphylococcus aureus bacteremia

OBJECTIVE

Recent data indicate that ticagrelor, used in acute coronary syndromes (ACS), has antibacterial effects against Staphylococcus sp. and other effects that may help management of infection. The primary objective of this study was to evaluate the protective effect of ticagrelor in patients who have had an ACS event and the risk of developing Staphylococcus aureus bacteremia (SAB) compared to a propensity-matched cohort receiving clopidogrel.

METHODS

This study was a retrospective, nationwide analysis of all patients presenting to any percutaneous coronary intervention-performing Veterans Affairs Medical Center with an ACS episode and resultant prescription for clopidogrel or ticagrelor. The primary outcome was the comparative rate of SAB in patients receiving ticagrelor vs. clopidogrel.

RESULTS

Analysis involved 24 456 patients on ticagrelor and 277 277 patients on clopidogrel. There was a statistically significant difference in the number of patients developing SAB between the propensity-matched groups (32 [0.13%] of 24 456 for ticagrelor vs. 71 [0.29%] of 24 456 for clopidogrel; odds ratio (OR), 0.43; 95% confidence interval (CI), 0.28-0.65; P<0.0001). Multivariate logistic regression showed that receipt of clopidogrel, comorbid dermatologic condition, comorbid hematologic condition, and baseline anemia were independently associated with the development of SAB.

CONCLUSIONS

The study findings align with recent reports that ticagrelor may have a beneficial role in the prevention of SAB.

Escalation of antimicrobial resistance among MRSA part 2: focus on infections and treatment

INTRODUCTION

MRSA is associated with causing a variety of infections including skin and skin structure infections, catheter and device-related (e.g. central venous catheter, prosthetic heart valve) infections, infectious endocarditis, blood stream infections, bone, and joint infections (e.g. osteomyelitis, prosthetic joint, surgical site), central nervous system infections (e.g. meningitis, brain/spinal cord abscess, ventriculitis, hydrocephalus), respiratory tract infections (e.g. hospital-acquired pneumonia, ventilator-associated pneumonia), urinary tract infections, and gastrointestinal infections. The emergence and spread of multidrug resistant (MDR) MRSA clones has limited therapeutic options. Older agents such as vancomycin, linezolid and daptomycin and a variety of newer MRSA antimicrobials and combination therapy are available to treat serious MRSA infections.

AREAS COVERED

The authors discuss infections caused by MRSA as well as common older and newer antimicrobials and combination therapy for MRSA infections. A literature search of MRSA was performed via PubMed (up to September 2022), using the keywords: antimicrobial resistance; β-lactams; multidrug resistance, Staphylococcus aureus, vancomycin; glycolipopeptides.

EXPERT OPINION

Innovation, discovery, and development of new and novel classes of antimicrobial agents are critical to expand effective therapeutic options. The authors encourage the judicious use of antimicrobials in accordance with antimicrobial stewardship programs along with infection-control measures to minimize the spread of MRSA.

Clinical and Epidemiological Characteristics of Persistent Bacteremia: A Decadal Observational Study

Background: Bloodstream infections (BSIs), including persistent bacteremia (PB), are a leading source of morbidity and mortality globally. PB has a higher mortality rate than non- PB, but the clinical aspects of PB in terms of the causative pathogens and the presence of clearance of PB are not well elucidated. Therefore, this study aimed to describe the clinical and epidemiological characteristics of PB in a real-world clinical setting. Methods: We performed a retrospective observational survey of patients who underwent blood culture between January 2012 and December 2021 at Tohoku University Hospital. Cases of PB were divided into three groups depending on the causative pathogen: gram-positive cocci (GPC), gram-negative rods (GNRs), and Candida spp. For each group, we examined the clinical and epidemiological characteristics of PB, including differences in clinical features depending on the clearance of PB. The main outcome variable was mortality, assessed as early (30-day), late (30-90 day), and 90-day mortality. Results: Overall, we identified 31,591 cases of single bacteremia; in 6709 (21.2%) cases, the first blood culture was positive, and in 3124 (46.6%) cases, a follow-up blood culture (FUBC) was performed. Of the cases with FUBCs, 414 (13.2%) were confirmed to be PB. The proportion of PB cases caused by Candida spp. was significantly higher (29.6%, 67/226 episodes) than that for GPC (11.1%, 220/1974 episodes, p < 0.001) and GNRs (12.1%, 100/824 episodes, p < 0.001). The Candida spp. group also had the highest late (30-90 day) and 90-day mortality rates. In all three pathogen groups, the subgroup without the clearance of PB tended to have a higher mortality rate than the subgroup with clearance. Conclusions: Patients with PB due to Candida spp. have a higher late (30-90 day) and 90-day mortality rate than patients with PB due to GPC or GNRs. In patients with PB, FUBCs and confirming the clearance of PB are useful to improve the survival rate.

Redefining Staphylococcus aureus bacteremia: A structured approach guiding diagnostic and therapeutic management

The current duration of therapy in patients with Staphylococcus aureus bacteremia (SAB) is based on differentiating complicated from uncomplicated disease. While this approach allows clinicians and investigators to group SAB patients into broadly similar clinical categories, it fails to account for the intrinsic heterogeneity of SAB. This is due in part to the fact that risk factors for metastatic infection and confirmed metastatic infection are considered as equivalent in most scoring systems. In this viewpoint, we propose a two-step system of categorizing patients with SAB. Initially, patients with SAB would be categorized as 'high risk' or 'low risk' for metastatic infection based upon an initial set of diagnostic procedures. In the second step, patients identified as 'high-risk' would undergo additional diagnostic evaluation. The results of this stepwise diagnostic evaluation would define a 'final clinical diagnosis' to inform an individualized final treatment plan.

Persistent Methicilin-Resistant Staphylococcus aureus Bacteremia: Resetting the Clock for Optimal Management

A positive follow-up blood culture for methicillin-resistant Staphylococcus aureus (MRSA) while on seemingly appropriate therapy is a common and ominous development. However, the definition and management of persistent MRSA bacteremia is unstandardized. In this Opinion Paper, we identify the presence of bacteremia for > 1 calendar day as a "worry point" that should trigger an intensive diagnostic evaluation to identify metastatic infection sites. Next, we define the duration of MRSA bacteremia that likely constitutes antibiotic failure and outline a potential management algorithm for such patients. Finally, we propose pragmatic clinical trial designs to test treatment strategies for persistent MRSA bacteremia.

Rapid detection of Staphylococcus aureus and Streptococcus pneumoniae by real-time analysis of volatile metabolites

Early detection of pathogenic bacteria is needed for rapid diagnostics allowing adequate and timely treatment of infections. In this study, we show that secondary electrospray ionization–high resolution mass spectrometry (SESI-HRMS) can be used as a diagnostic tool for rapid detection of bacterial infections as a supportive system for current state-of-the-art diagnostics. Volatile organic compounds (VOCs) produced by growing S. aureus or S. pneumoniae cultures on blood agar plates were detected within minutes and allowed for the distinction of these two bacteria on a species and even strain level within hours. Furthermore, we obtained a fingerprint of clinical patient samples within minutes of measurement and predominantly observed a separation of samples containing live bacteria compared to samples with no bacterial growth. Further development of this technique may reduce the time required for microbiological diagnosis and should help to improve patient’s tailored treatment.

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Real-time mass spectrometry shows potential as a tool for microbiological diagnosis

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Bacterial volatile metabolites from 1 × 10³ CFUs are detected within minutes

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S. aureus and S. pneumoniae can be distinguished on species and even strain level

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Complex clinical samples cluster according to presence or absence of viable bacteria

Update on Staphylococcus aureus bacteraemia

PURPOSE OF REVIEW

To review recently published evidence relevant to Staphylococcus aureus bacteremia (SAB).

RECENT FINDINGS

Staphylococcus aureus is the most common pathogen causing co-infections and superinfections in patients with COVID-19. Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia ratios have sharply risen during the pandemic. SAB mortality is 18% at 1 month and 27% at 3 months but has gradually decreased over the last 30 years. Recurrences and reinfections are common (9%). Standardised items to define complicated SAB, and a new cut-off defining persisting bacteremia after 2 days with positive blood cultures have been proposed. Multiple antibiotic combinations have been trialled including vancomycin or daptomycin with β-lactams, fosfomycin, or clindamycin, without significant results. In the recently published guidelines, vancomycin remains the first line of treatment for MRSA bacteremia. For the management of methicillin-susceptible Staphylococcus aureus , cefazolin less frequently causes acute kidney injury than flucloxacillin, and when susceptibility is demonstrated, de-escalation to penicillin G is suggested.

SUMMARY

Our review confirms that Staphylococcus aureus represents a special aetiology among all causes of bloodstream infections. Pending results of platform and larger trials, its distinct epidemiology and determinants mandate careful integration of clinical variables and best available evidence to optimize patient outcomes.

Risk Factors of Recurrent Infection in Patients with Staphylococcus aureus Bacteremia: a Competing Risk Analysis

Although several clinical variables have been reported as risk factors for recurrence of Staphylococcus aureus infection, most studies have not considered competing risk events that may overestimate the risk. In this study, we performed competing risk analysis to identify risk factors related to 90-day recurrence in patients with S. aureus bacteremia (SAB) using a large cohort data from a single tertiary hospital in South Korea. All adults who experienced SAB during admission were prospectively enrolled from August 2008 to December 2019. After the day of the first positive blood culture, recurrence and all-cause mortality were assessed for 90 days. Recurrence was defined as a development of symptoms or signs of infection with or without repeated bacteremia after >7 days of negative blood culture and clinically apparent improvement. Subdistribution hazard ratios (sHR) for recurrence and all-cause mortality were estimated using Fine and Gray models. Of 1,725 SAB patients, including 885 cases (51.3%) of methicillin-resistant S. aureus (MRSA) bacteremia, 85 (5.0%) experienced recurrence during the study period. In a multivariate Fine and Gray regression model, the presence of a vascular graft (subdistribution HR [sHR], 3.48; 95% confidence interval [CI], 1.90-6.40), nasal MRSA carriage (sHR, 2.10; 95% CI, 1.28-3.44), methicillin resistance (sHR, 1.69; 95% CI, 1.00-2.84), and rifampicin resistance (sHR, 2.20; 95% CI, 1.12-4.33) were significantly associated with 90-day recurrence. In a large cohort of SAB patients with a high prevalence of MRSA, indwelling vascular graft, nasal MRSA carriage, methicillin resistance, and rifampicin resistance were potential risk factors for recurrence of S. aureus infection.

Clinical and Microbiological Characteristics of Recurrent Escherichia coli Bacteremia

The causative agents of recurrent Escherichia coli bacteremia can be genetically identical or discordant, but the differences between them remain unclear. This study aimed to explore these differences, with regard to their clinical and microbiological features. Patients were recruited from a Japanese tertiary teaching hospital based on blood culture data and the incidence of recurrent E. coli bacteremia. We compared the patients' clinical and microbiological characteristics between the two groups (those with identical or discordant E. coli bacteremia) divided by the result of enterobacterial repetitive intergenic consensus PCR. Among 70 pairs of recurrent E. coli bacteremia strains, 49 pairs (70%) were genetically identical. Patients with genetically identical or discordant E. coli bacteremia were more likely to have renal failure or neoplasms, respectively. The virulence factor (VF) scores of genetically identical E. coli strains were significantly higher than those of genetically discordant strains, with the prevalence of eight VF genes being significantly higher in genetically identical E. coli strains. No significant differences were found between the two groups regarding antimicrobial susceptibility and biofilm formation potential. This study showed that genetically identical E. coli bacteremia strains have more VF genes than genetically discordant strains in recurrent E. coli bacteremia.

IMPORTANCEEscherichia coli causes bloodstream infection, although not all strains are pathogenic to humans. In some cases, this infection reoccurs, and several reports have described the clinical characteristics and/or molecular microbiology of recurrent Escherichia coli bacteremia. However, these studies focused on patients with specific characteristics, and they included cases caused by microorganisms other than Escherichia coli. Hence, little is known about the pathogenicity of Escherichia coli isolated from the recurrent one. The significance of our study is in evaluating the largest cohorts to date, as no cohort studies have been conducted on this topic.