A population-based study of the appearances of enteric Campylobacter and non-typhoidal Salmonella infections on computed tomography.

BACKGROUND: Swift identification and diagnosis of gastrointestinal infections are crucial for prompt treatment, prevention of complications, and reduction of the risk of hospital transmission. The radiological appearance on computed tomography could potentially provide important clues to the etiology of gastrointestinal infections. We aimed to describe features based on computed tomography of patients diagnosed with Campylobacter, Salmonella or Shigella infections in South Sweden. METHODS: This was a retrospective observational population-based cohort study conducted between 2019 and 2022 in Skåne, southern Sweden, a region populated by 1.4 million people. Using data from the Department of Clinical Microbiology combined with data from the Department of Radiology, we identified all patients who underwent computed tomography of the abdomen CTA two days before and up to seven days after sampling due to the suspicion of Campylobacter, Salmonella or Shigella during the study period. RESULTS: A total of 215 CTAs scans performed on 213 patients during the study period were included in the study. The median age of included patients was 45 years (range 11-86 years), and 54% (114/213) of the patients were women. Of the 215 CTAs, 80% (n = 172) had been performed due to Campylobacter and 20% (n = 43) due to Salmonella enteritis. CTA was not performed for any individual diagnosed with Shigella during the study period. There were no statistically significant differences in the radiological presentation of Campylobacter and Salmonella infections. CONCLUSION: The most common location of Campylobacter and Salmonella infections was the cecum, followed by the ascending colon. Enteric wall edema, contrast loading of the affected mucosa, and enteric fat stranding are typical features of both infections. The CTA characteristics of Campylobacter and Salmonella are similar, and cannot be used to reliably differentiate between different infectious etiologies.

Non-betahemolytic streptococcal bacteremia, cardiac implantable electronic device, endocarditis, extraction, and outcome; a population-based retrospective cohort study.

PURPOSE: Patients with non-beta-hemolytic streptococcal bacteremia (NBHSB) are at risk of infective endocarditis (IE). Patients with cardiac implantable electronic device (CIED) have been described to have an increased risk of IE. The aim of the study was to describe a population-based cohort of patients with NBHSB and CIED and variables associated with IE and recurrent NBHSB. METHODS: All episodes with NBHSB in blood culture from 2015 to 2018 in a population of 1.3 million inhabitants were collected from the Clinical Microbiology Laboratory, Lund, Sweden. Through medical records, patients with CIED during NBHSB were identified and clinical data were collected. Patients were followed 365 days after NBHSB. RESULTS: Eighty-five episodes in 79 patients with CIED and NBHSB constituted the cohort. Eight patients (10%) were diagnosed with definite IE during the first episode, five of whom also had heart valve prosthesis (HVP). In 39 patients (49%) transesophageal echocardiography (TEE) was performed of which six indicated IE. Four patients had the CIED extracted. Twenty-four patients did not survive (30%) the study period. Four patients had a recurrent infection with NBHSB with the same species, three of whom had HVP and had been evaluated with TEE with a negative result during the first episode and diagnosed with IE during the recurrency. CONCLUSION: The study did not find a high risk of IE in patients with NBHSB and CIED. Most cases of IE were in conjunction with a simultaneous HVP. A management algorithm is suggested.

Lower specificity of the ESC2023 diagnostic criteria for infective endocarditis when spondylodiscitis is regarded as a vascular phenomenon.

The ESC diagnostic criteria for infective endocarditis (IE) added spondylodiscitis as minor diagnostic criterion. Of patients with Staphylococcus aureus, streptococcal or Enterococcus faecalis bacteremia, 11 of 1807 episodes were reclassified to definite IE of which nine were not treated as IE. Spondylodiscitis as a minor criterion decreases specificity of the criteria.

Campylobacter Infections With and Without Bacteremia: A Comparative Retrospective Population-Based Study.

Background: Bacteremia with species in the genus Campylobacter is rare, and knowledge of the disease course in comparison with Campylobacter enteritis is limited. Methods: This is a retrospective population-based study. Episodes of Campylobacter bacteremia and Campylobacter enteritis with a concurrent negative blood culture result that occurred between 2015 and 2022 in southern Sweden were identified through the laboratory database. Medical records were reviewed, and clinical features between patients with bacteremic Campylobacter infections were compared with patients with Campylobacter spp found in feces. Results: The study included 29 bacteremic infections with Campylobacter and 119 cases of Campylobacter spp found in feces. Patients with Campylobacter bacteremia were significantly older than those with enteritis (72 years [IQR, 58-62] vs 58 years [IQR, 33-67], P < .0001). Eleven patients with bacteremia developed sepsis within 48 hours from blood culturing, and no patient died within 30 days from hospital admission. Conclusions: Campylobacter bacteremia is rare and occurs mainly in the elderly with comorbidities. In comparison with Campylobacter infections limited to the gastrointestinal tract, patients with bacteremic Campylobacter infections are older and seem more prone to develop sepsis. Classical gastroenteritis symptoms in bacteremic cases with Campylobacter may be absent.

Performance of the 2023 Duke-International Society of Cardiovascular Infectious Diseases Diagnostic Criteria for Infective Endocarditis in Relation to the Modified Duke Criteria and to Clinical Management-Reanalysis of Retrospective Bacteremia Cohorts.

BACKGROUND: Revised diagnostic criteria for infective endocarditis (IE), the 2023 Duke-ISCVID criteria, were recently presented and need validation. Here, we compare the 2000 modified Duke criteria for IE with Duke-ISCVID among patients with bacteremia and relate the diagnostic classification to IE treatment. METHODS: We reanalyzed patient cohorts with Staphylococcus aureus, Staphylococcus lugdunensis, non-ß-hemolytic streptococci, Streptococcus-like bacteria, Streptococcus dysgalactiae, Enterococcus faecalis, and HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella) bacteremia. Episodes were classified as definite, possible, or rejected IE with the modified Duke and Duke-ISCVID criteria. Reclassification included the microbiology criteria, positron emission tomography-computed tomography, and cardiac implanted electronic devices. To calculate sensitivity, patients treated for IE were considered as having IE. RESULTS: In 4050 episodes of bacteremia, the modified Duke criteria assigned 307 episodes (7.6%) as definite IE, 1190 (29%) as possible IE, and 2553 (63%) as rejected IE. Using the Duke-ISCVID criteria, 13 episodes (0.3%) were reclassified from possible to definite IE, and 475 episodes (12%) were reclassified from rejected to possible IE. With the modified Duke criteria, 79 episodes that were treated as IE were classified as possible IE, and 11 of these episodes were reclassified to definite IE with Duke-ISCVID. Applying the decision to treat for IE as a reference standard, the sensitivity of the Duke-ISCVID criteria was 80%. None of the 475 episodes reclassified to possible IE were treated as IE. CONCLUSIONS: The Duke-ISCVID criteria reclassified a small proportion of episodes to definite IE at the expense of more episodes of possible IE. Future criteria should minimize the possible IE group while keeping or improving sensitivity.

A retrospective observational study of 1000 consecutive patients tested with the FilmArray® Meningitis/Encephalitis panel: clinical diagnosis at discharge and microbiological findings.

FilmArray® Meningitis/Encephalitis panel (FAME-p) is used to diagnose central nervous system (CNS) infections. In this study, we investigated performance of FAME-p compared to comparator assays (CA), and for the first time, clinical diagnosis at discharge (CDD). 1000 consecutive patients with a cerebrospinal fluid (CSF) sample analyzed with FAME-p were identified. As CA, culture, polymerase chain reaction and cryptococcal antigen test were used. Medical records of patients were obtained. A CDD of CNS infection was made in 139 of 1000 CSF samples. FAME-p was positive in 66 samples with 44 viral and 22 bacterial agents. Thirteen FAME-p findings were not confirmed by CA, with four discrepant results remaining after comparison with the CDD. Positive percentage agreement (PPA) calculated against CA was 100%. Negative percentage agreement (NPA) calculated against CA was 94.4-99.8% for Haemophilus influenzae, Listeria monocytogenes, Streptococcus agalactiae, S. pneumoniae and varicella-zoster virus (VZV). NPA calculated against CDD was higher (compared to CA) for L. monocytogenes, S. agalactiae and VZV (100%), and lower for Escherichia coli, enterovirus and herpes simplex virus 2 (50-83.3%). NPA of FAME-p for human herpes virus 6 was difficult to interpret. Eighty-four cases received diagnosis of CNS-infection despite negative FAME-p. The four most common non-infectious etiologies were primary headache disorders, cranial nerve palsies, neuroinflammatory disorders and seizure. Although FAME-p shows good performance in diagnosis of CNS infections, result of FAME-p should be interpreted carefully. Considering infectious diseases not covered by FAME-p as well as non-infectious differential diagnoses is important in this context.

Eubacterium bacteremia - a retrospective observational study of a seldom found anaerobic pathogen.

BACKGROUND: Human infections due to Eubacterium are rare and knowledge of the condition is limited. This study aimed to describe clinical characteristics and outcome in patients with Eubacterium bacteremia. METHODS: Episodes of Eubacterium bacteremia were identified through the clinical microbiology laboratory in Lund, Sweden. Medical records were retrospectively reviewed. Blood isolates of Eubacterium were collected and antibiotic susceptibility testing was performed with agar dilution. RESULTS: Seventeen patients with Eubacterium bacteremia were identified of whom six had monomicrobial bacteremia. The incidence was 1.7 cases of Eubacterium bacteremia per million inhabitants and year. The median age was 67 years (interquartile range 63-79 years), and six patients had some form of malignancy. Most of the patients an abdominal focus of infection and the 30-day mortality was low (n = 1). CONCLUSIONS: Invasive infections with Eubacterium have a low incidence. The condition has a low mortality and an abdominal focus of infection, and malignancy, is common.

A population-based study on the incidence and aetiology of infectious complications in peritoneal dialysis in South Sweden.

BACKGROUND: Peritonitis is a major cause of morbidity in peritoneal dialysis (PD) and an independent risk factor for elevated all-cause mortality. The aims of this study were to report the incidence, trend, aetiology, and antimicrobial susceptibility of PD-associated peritonitis and catheter-related infections in South Sweden between 2011-2020. METHODS: This population-based observational cohort study included all patients with PD between the years 2011-2020 in the county of Skåne. Data was accessed through the Swedish Renal Registry and the Department of Clinical Microbiology in Lund. Definitions issued by the International Society for Peritoneal Dialysis were implemented to assess PD-associated infections. RESULTS: Medical records of 675 paediatric and adult PD patients were eligible for inclusion. Of those, 208 (31%) were female and the median age was 67 years (range 0-91). The overall rate of PD-peritonitis was 0.38 episodes per year at risk. Out of 484 episodes of peritonitis, 61% (n = 295) were caused by Gram-positive bacteria. There were 289 occurrences of exit site infections, of which most (n = 152, 53%) were Gram-positive. Tunnel infections occurred in 16 episodes and were caused by S. aureus or P. aeruginosa. Among all isolates, 37 were of MRSE, four of ESBL-producing E. coli, and one of MRSA. CONCLUSION: The crude rate of PD-peritonitis was stable during the study period. Gram-positive bacteria dominated the microbial aetiology, and antibiotic resistance was limited. It is important to monitor the aetiology, incidence, and resistance rates in PD-associated infections, to base empirical antibiotic regimens and facilitate prevention.

Risk factors for and consequences of positive valve cultures in patients who undergo cardiac surgery while receiving antimicrobial treatment for infective endocarditis.

INTRODUCTION: Cardiac surgery is required in up to half of the patients with infective endocarditis (IE). Positive valve cultures have been associated with higher in-hospital mortality. The aims were to identify risk factors for positive valve cultures and its relation to outcome. METHODS: Patients subjected to heart valve cultures due to surgery for IE in Skåne University Hospital, Lund, between 2012 and 2021 were identified through microbiology records. Risk factors for positive valve cultures and information on mortality and relapse were retrieved through medical records. Univariable and multivariable logistic regressions were performed. RESULTS: A total of 345 episodes with IE in 337 patients subjected to cardiac surgery were included and valve cultures were positive in 78 (23%) episodes. In multivariable logistic regression, preoperative fever (adjusted odds ratio (AOR) 2.6, 95% confidence interval (CI) 1.2-5.6, p = 0.02), prosthetic heart valve (AOR 3.3, CI 1.4-7.9, p = 0.01), a single affected valve (AOR 4.8, CI 1.2-20, p = 0.03), blood culture findings of S. aureus, enterococci, or coagulase negative staphylococci compared to viridans streptococci (AOR 20-48, p < 0.001), and a shorter duration of antibiotic treatment (p < 0.001), were associated to positive valve culture. One-year mortality was 13% and a relapse was identified in 2.5% of episodes. No association between positive valve cultures and one-year mortality or relapse was identified. CONCLUSIONS: Positive valve cultures were associated to short preoperative antibiotic treatment, IE caused by staphylococci, preoperative fever and prosthetic valve but not to relapse or mortality.

Biofilm formation on endovascular aneurysm repair (EVAR) grafts-a proof of concept in vitro model.

OBJECTIVES: An endovascular aneurysm repair (EVAR) graft is a catheter-implanted vascular prosthesis and is the preferred treatment for patients with aortic aneurysm. If an EVAR graft becomes the focus of infection, the treatment possibilities are limited because it is technically difficult to remove the graft to obtain source control. This study examines whether Pseudomonas aeruginosa and Staphylococcus aureus form biofilm on EVAR prostheses. METHODS: EVAR graft sections were exposed to bacteria at 102 or 108 colony forming units (CFU)/mL in lysogeny broth and Krebs-Ringer at 37°C, bacterial biofilm formation was evaluated by scanning electron microscopy and counting CFU on the graft sections after antibiotic exposure at × 10 minimal inhibitory concentration. Bacteria were tested for tolerance to benzylpenicillin, tobramycin, and ciprofloxacin. RESULTS: Bacterial exposure for 15 minutes established biofilms on all prosthesis fragments (6/6 replicates). After 4 hours, bacteria were firmly attached to the EVAR prostheses and resisted washing. After 18-24 hours, the median CFU/g of EVAR graft reached 5.2 × 108 (1.15 × 108-1.1 × 109) for S. aureus and 9.1 × 107 (3.5 × 107-6.25 × 108) for P. aeruginosa. Scanning electron microscopy showed bacterial attachment to the graft pieces. There was a time-dependent development of tolerance with approximately 20 (tobramycin), 560 (benzylpenicillin), and 600 (ciprofloxacin) times more S. aureus surviving antibiotic exposure in 24- compared with 0-hour-old biofilm. Five (tobramycin) and 170 times (ciprofloxacin) more P. aeruginosa survived antibiotic exposure in 24- compared with 0-hour-old biofilms. DISCUSSION: Our results show that bacteria can rapidly adhere to and subsequently form antibiotic-tolerant biofilms on EVAR graft material in concentrations equivalent to levels seen in transient bacteraemia in vivo. Potentially, the system can be used for identifying optimal treatment combinations for infected EVAR prosthesis.

A Population-Based Study of Unfavorable Prognostic Factors Associated With Pyogenic Liver Abscess.

Background: Pyogenic liver abscess (PLA) is a rare entity that is associated with substantial mortality and morbidity. Our objective was to investigate variables associated with mortality and subsequent PLA in patients diagnosed with PLA in southern Sweden. Methods: We conducted a population-based observational study comprising all episodes of PLA that occurred between 2011 and 2020 in the county of Skåne, southern Sweden. The primary outcome was defined as all-cause 90-day mortality and the secondary outcome was defined as the occurrence of a subsequent PLA. Results: A total of 452 episodes of PLA occurred in 360 patients during the study period. The 90-day mortality rate was 16% (n = 58) and the subsequent PLA rate was 20% (n = 92). In a multivariable logistic regression model, female sex (odds ratio [OR], 2.0 [95% confidence interval {CI}, 1.1-3.9]), malignancy (OR, 3.7 [95% CI, 1.9-7.1]), liver failure (OR, 6.3 [95% CI, 2.7-14.5]), and polymicrobial findings (OR, 3.8 [95% CI, 2.2-6.9]) were associated with death within 90 days (P < .05). Male sex (OR, 2.1 [95% CI, 1.2-3.6]), malignancy (OR, 2.1 [95% CI, 1.3-3.6]), age (64-74 years: OR, 2.5 [95% CI, 1.3-4.8]), and chronic liver disease (OR, 3.0 [95% CI, 1.4-6.5]) were associated with the risk of subsequent PLA (P ≤ .01). Conclusions: Identifying different clinical variables associated with an unfavorable outcome may improve the management and treatment of patients with PLA and thus prevent the risk of death and subsequent PLA.

Clinical Significance of a 16S-rDNA Analysis of Heart Valves in Patients with Infective Endocarditis: a Retrospective Study.

A substantial proportion of patients with infective endocarditis (IE) are subjected to heart valve surgery. Microbiological findings on valves are important both for diagnostics and for tailored antibiotic therapy, post-operatively. The aims of this study were to describe microbiological findings on surgically removed valves and to examine the diagnostic benefits of 16S-rDNA PCR and sequencing (16S-analysis). Adult patients who were subjected to heart valve surgery for IE between 2012 and 2021 at Skåne University Hospital, Lund, where a 16S-analysis had been performed on the valve, constituted the study population. Data were gathered from medical records, and the results from blood cultures, valve cultures, and 16S-analyses of valves were compared. A diagnostic benefit was defined as providing an agent in blood culture negative endocarditis, providing a new agent in episodes with positive blood cultures, or confirming one of the findings in episodes with a discrepancy between blood and valve cultures. 279 episodes in 272 patients were included in the final analysis. Blood cultures were positive in 259 episodes (94%), valve cultures in 60 episodes (22%), and 16S-analyses in 227 episodes (81%). Concordance between the blood cultures and the 16S-analysis was found in 214 episodes (77%). The 16S-analyses provided a diagnostic benefit in 25 (9.0%) of the episodes. In blood culture negative endocarditis, the 16S-analyses had a diagnostic benefit in 15 (75%) of the episodes. A 16S-analysis should be routinely performed on surgically removed valves in blood culture negative endocarditis. In patients with positive blood cultures, 16S-analysis may also be considered, as a diagnostic benefit was provided in some patients. IMPORTANCE This work demonstrates that it can be of importance to perform both cultures and analysis using 16S-rDNA PCR and sequencing of valves excised from patients undergoing surgery for infective endocarditis. 16S-analysis may help both to establish a microbiological etiology in cases of blood culture negative endocarditis and to provide help in situations where there are discrepancies between valve and blood cultures. In addition, our results show a high degree of concordance between blood cultures and 16S-analyses, indicating that the latter has a high sensitivity and specificity for the etiological diagnosis of endocarditis in patients who were subjected to heart valve surgery.

Infection or Contamination with Rothia, Kocuria, Arthrobacter and Pseudoglutamicibacter-a Retrospective Observational Study of Non-Micrococcus Micrococcaceae in the Clinic.

Rothia, Kocuria, Arthrobacter, and Pseudoglutamicibacter are bacterial species within the family Micrococcaeae. Knowledge of human infections due to these bacteria is limited. This study aimed to examine features of infections caused by non-Micrococcus Micrococcaeae (NMM). Findings of NMM from blood cultures and other sterile cultures from 2012 to 2021 were identified from the records of the Department of Clinical Microbiology in Region Skåne, Lund, Sweden. Medical records were retrospectively reviewed. True infection was defined as having signs of infection, no other more likely pathogen, and no other focal infection, together with two positive blood cultures or one positive blood culture and an intravascular device. A total of 197 patients with findings of NMM in blood cultures were included. Among adult patients with bacteremia, 29 patients (22%) were considered to have a true infection. Adults with true infection were significantly more likely to have malignancy (69%), leukopenia (62%), and treatment with chemotherapeutics (66%) compared to patients with contaminated samples (24%, 3%, and 8%, respectively) (P < 0.001). A total of 31 patients had findings of NMM in other sterile cultures, and infections were considered true in joints (n = 4), a pacemaker (n = 1), and peritoneal dialysis fluid (n = 1). Infections due to NMM occur but are rare. Growth of NMM in blood cultures should be suspected to be a true infection mainly in immunocompromised patients.

Increasing incidence of pyogenic liver abscess in Southern Sweden: a population-based study from 2011 to 2020.

BACKGROUND: Pyogenic liver abscess (PLA) is a rare but potentially life-threatening disease, and estimates suggest a gradual increase in the incidence during the last decades. The primary aim of this study was to report the incidence, trend and aetiology of PLA during a decade in Southern Sweden. METHODS: This was a population-based observational cohort study between 2011 and 2020 in Skåne, Southern Sweden. Data were retrieved from the Swedish National Board of Health and Welfare for all individuals diagnosed with liver abscess (K750) according to ICD-10 (International Statistical Classification of Diseases, 10th revision). RESULTS: A total of 456 episodes of PLA occurred in 364 patients during the study period. The median age of the first PLA episode was 71 years (range 3-97) and 57% (n = 206) were men. The mean incidence of all patients was 3.4/100,000 person-years (range 1.8-5.2). The incidence increased almost three times, from 1.8/100,000 person-years in 2011 to 5.2/100,000 person-years in 2020. Streptococcus species, Escherichia coli and Klebsiella species accounted for the vast majority of both mono- and polymicrobial findings in both blood and local abscess cultures. 16s rDNA added information about aetiology in 37% of episodes. CONCLUSION: The incidence of PLA increased during the study period, and Streptococcus spp., Klebsiella spp. and E. coli dominated both blood and local cultures. Despite antimicrobial therapy, pathogens could be found in local abscess cultures several weeks into treatment. Increased use of 16s rDNA in the management of PLA could be beneficial.

Incidence, aetiology and temporal trend of bloodstream infections in southern Sweden from 2006 to 2019: a population-based study.

BackgroundBloodstream infections (BSI) are a public health concern, and infections caused by resistant bacteria further increase the overall BSI burden on healthcare.AimTo provide a population-based estimate of BSI incidence and relate this to the forthcoming demographic ageing western population change.MethodsWe retrieved positive blood cultures taken from patients in the Skåne region, southern Sweden, 2006-2019 from the Clinical Microbiology Department database and estimated incidence rates (IR), stratified by age (0-49, 50-64, 65-79, ≥ 80 years), sex, year, and species and described antimicrobial susceptibility for Enterobacterales.ResultsWe identified 944,375 blood culture sets, and 129,274 (13.7%) were positive. After deduplication and removal of contaminants, 54,498 separate BSI episodes remained. In total, 30,003 BSI episodes (55%) occurred in men. The overall IR of BSI was 307/100,000 person-years, with an average annual increase of 3.0%. Persons ≥ 80 years had the highest IR, 1781/100,000 person-years, as well as the largest increase. Escherichia coli (27%) and Staphylococcus aureus (13%) were the most frequent findings. The proportion of Enterobacterales isolates resistant to fluoroquinolones and third generation cephalosporins increased from 8.4% to 13.6%, and 4.9% to 7.3%, (p for trend < 0.001), with the largest increase in the oldest age group.ConclusionWe report among the highest BSI IRs to date worldwide, with a higher proportion among elderly persons and males, including resistant isolates. Given expected demographic changes, these results indicate a possible substantial future BSI burden, for which preventive measures are needed.

True infection or contamination in patients with positive Cutibacterium blood cultures-a retrospective cohort study.

Cutibacterium is a genus often considered a contaminant when present in blood cultures, but it can also cause severe infections, especially related to implanted foreign materials. We investigated the incidence and features of patients with true Cutibacterium infection. Patients with positive Cutibacterium blood cultures between the years 2015-2020 in southern Sweden were identified through microbiology records and medical records were studied retrospectively. Cutibacterium isolates were species determined using MALDI-TOF MS. Patients were classified as having true infection or contamination according to a definition considering both clinical and microbiological features and these groups were compared. A total of 313 episodes of positive Cutibacterium blood cultures were identified in 312 patients. Of these, 49 (16%, corresponding to an incidence of 6 cases per million inhabitants per year) were classified as true infections. The most common species was Cutibacterium acnes (87%), and the majority were elderly men with comorbidities. Patients with true Cutibacterium infection often had an unknown focus of infection (n = 21) or a focus in the respiratory tract (n = 18). We identified one episode of ventriculo-peritoneal shunt infection, three episodes of aortic stent-graft infection, and one episode of infective endocarditis. Two patients, where Cutibacterium was isolated at the site of infection, had only one positive blood culture. The finding of positive Cutibacterium blood cultures should not always be considered contamination. Definitions of true Cutibacterium bacteremia with a demand that more than one blood culture must be positive may miss true infections.

Dynamics of a Staphylococcus aureus infective endocarditis simulation model.

Infective endocarditis (IE) is a serious infection of the inner surface of heart, resulting from minor lesions in the endocardium. The damage induces a healing reaction, which leads to recruitment of fibrin and immune cells. This sterile healing vegetation can be colonized during temporary bacteremia, inducing IE. We have previously established a novel in vitro IE model using a simulated IE vegetation (IEV) model produced from whole venous blood, on which we achieved stable bacterial colonization after 24 h. The bacteria were organized in biofilm aggregates and displayed increased tolerance toward antibiotics. In this current study, we aimed at further characterizing the time course of biofilm formation and the impact on antibiotic tolerance development. We found that a Staphylococcus aureus reference strain, as well as three clinical IE isolates formed biofilms on the IEV after 6 h. When treatment was initiated immediately after infection, the antibiotic effect was significantly higher than when treatment was started after the biofilm was allowed to mature. We could follow the biofilm development microscopically by visualizing growing bacterial aggregates on the IEV. The findings indicate that mature, antibiotic-tolerant biofilms can be formed in our model already after 6 h, accelerating the screening for optimal treatment strategies for IE.

Get the Species Right: Aerococcus viridans is Likely not Responsible.

How to cite this article: Rasmussen M, Sunnerhagen T. Get the Species Right: Aerococcus viridans is Likely not Responsible. Indian J Crit Care Med 2022;26(10):1158.