Diagnostic yield of 18F-FDG PET/CT in suspected diagnosis of vascular graft infection: A prospective cohort study

Background. Prosthetic vascular graft infection (PVGI) is a severe complication associated with high morbidity and mortality. Clinical diagnosis is complex, requiring image testing such as CT angiography or leukocyte scintigraphy, which has considerable limitations. The aim of this study was to know the diagnostic yield of PET/CT with 18F-Fluorodeoxyglucose (18F-FDG) in patients with suspected PVGI. Methods. We performed a prospective cohort study including 49 patients with suspected PVGI, median age of 62 ± 14 years. Three uptake patterns were defined following published recommendations: (i) focal, (ii) patched (PVGI criteria), and (iii) diffuse (no PVGI criterion). Results. Sensitivity, specificity, and positive and negative predictive values for 18F-FDG-PET/ CT were 88%, 79%, 67%, and 93%, respectively. 18F-FDG-PET/CT identified 14/16 cases of PVGI showing a focal (n = 10) or patched pattern (n = 4), being true negative in 26/33 cases with either a diffuse pattern (n = 16) or without uptake (n = 10). Five of the seven false-positive cases (71%) showed a patched pattern and all coincided with the application of adhesives for PVG placement. Conclusions. 18F-FDG-PET/CT is a useful technique for the diagnosis of PVGI. A patched pattern on PET/CT in patients in whom adhesives were applied for prosthetic vascular graft placement does not indicate infection. (J Nucl Cardiol 2018) Key Words: Fluorodeoxyglucose (FDG) Æ diagnostic and prognostic application Æ PET/CT imagin

Evaluation of the MagicplexTM sepsis real-time test for the rapid diagnosis of bloodstream infections in adults

Sepsis is a serious health condition worldwide, affecting more than 30 million people globally each year. Blood culture (BC) is generally used to diagnose sepsis because of the low quantity of microbes occurring in the blood during such infections. However, ~50% of bloodstream infections (BSI) give negative BC, this figure being higher for sepsis, which delays the start of appropriate antimicrobial therapy. This prospective study evaluated a multiplex real-time polymerase chain reaction, the MagicplexTM Sepsis test (MP), for the detection of pathogens from whole blood, comparing it to routine BC. We analyzed 809 blood samples from 636 adult patients, with 132/809 (16.3%) of the samples positive for one or more relevant microorganism according to BC and/or MP. The sensitivity and specificity of MP were 29 and 95%, respectively, while the level of agreement between BC and MP was 87%. The rate of contaminated samples was higher for BC (10%) than MP (4.8%) (P < 0.001). Patients with only MP-positive samples were more likely to be on antimicrobial treatment (47%) than those with only BC-positive samples (18%) (P = 0.002). In summary, the MP test could be useful in some clinical setting, such as among patients on antibiotic therapy. Nevertheless, a low sensitivity demonstrated impairs its use as a part of a routine diagnostic algorithm

Outcome of Enterococcus faecalis infective endocardits according to the length of antibiotic therapy: Prelininary data from a cohort of 78 patients.

Background International guidelines recommend 4 weeks of treatment with ampicillin plus gentamicin (A+G) for uncomplicated native valve Enterococcus faecalis infective endocarditis (EFIE) and 6 weeks in the remaining cases. Ampicillin plus ceftriaxone (A+C) is always recommended for at least 6w, with no available studies assessing its suitability for 4w. We aimed to investigate differences in the outcome of EFIE according to the duration (4 versus 6 weeks) of antibiotic treatment (A+G or A+C). Methods Retrospective analysis from a prospectively collected cohort of 78 EFIE patients treated with either A+G or A+C. Results 32 cases (41%) were treated with A+G (9 for 4w, 28%) and 46 (59%) with A+C (14 for 4w, 30%). No significant differences were found in 1-year mortality according to the type of treatment (31% and 24% in A+G and A+C, respectively; P = 0.646) or duration (26% and 27% at 4 and 6w, respectively; P = 0.863). Relapses were more frequent among survivors treated for 4w than in those treated for 6w (3/18 [17%] at 4w and 1/41 [2%] at 6w; P = 0.045). Three out of 4 (75%) relapses occurred in cirrhotic patients. Conclusions A 4-week course of antibiotic treatment might not be suitable neither for A+G nor A+C for treating uncomplicated native valve EFIE

Time-to-positivity, type of culture media and oxidase test performed on positive blood culture vials to predict Pseudomonas aeruginosa in patients with Gram-negative bacilli bacteraemia

OBJECTIVE: The aim of this study was to determine the usefulness of oxidase test and time-to-positivity (TTP) in aerobic and anaerobic blood culture vials to detect the presence of Pseudomonas aeruginosa in patients with Gram-negative bacilli (GNB) bacteraemia. METHODS: TTP was recorded for each aerobic and anaerobic blood culture vial of monomicrobial bacteraemia due to GNB. Oxidase test was performed in a pellet of the centrifuged content of the positive blood culture. An algorithm was developed in order to perform the oxidase test efficiently taking into account TTP and type of vial. RESULTS: A total of 341 episodes of GNB bacteraemia were analysed. Sensitivity, specificity, positive predictive value and negative predictive value of the oxidase test performed on positive vials with GNB to predict P. aeruginosa were 95%, 99%, 91%, and 99%, respectively. When growth was first or exclusively detected in anaerobic vials, P. aeruginosa was never identified hence the performance of the oxidase test could be avoided. When growth was only or first detected in aerobic vials, a TTP≥8h predicted P. aeruginosa in 37% or cases (63 of 169), therefore oxidase test is highly recommended. CONCLUSIONS: Oxidase test performed onto positive blood culture vials previously selected by TTP and type of vials is an easy and inexpensive way to predict P. aeruginosa. In most cases, this can lead to optimization of treatment in less than 24 hours

Rapid Diagnosis of Staphylococcal Catheter-Related Bacteraemia in Direct Blood Samples by Real-Time PCR

Catheter-related bacteremia (CRB) is an important cause of morbidity and mortality among hospitalized patients, being staphylococci the main etiologic agents. The objective of this study was to assess the use of a PCR-based assay for detection of staphylococci directly from blood obtained through the catheter to diagnose CRB caused by these microorganisms and to perform a cost-effectiveness analysis. A total of 92 patients with suspected CRB were included in the study. Samples were obtained through the catheter. Paired blood cultures were processed by standard culture methods and 4 ml blood samples were processed by GeneXpert-MRSA assay for the detection of methicillin-susceptible (MSSA) or methicillin-resistant (MRSA) Staphylococcus aureus, and methicillin-resistant coagulase-negative staphylococci (MR-CoNS). Sixteen CRB caused by staphylococci were diagnosed among 92 suspected patients. GeneXpert detected 14 out of 16 cases (87.5%), including 4 MSSA and 10 MR-CoNS in approximately 1 hour after specimen receipt. The sensitivity and specificity of GeneXpert were 87.5% (CI 95%: 60.4-97.8) and 92.1% (CI 95%: 83-96.7), respectively, compared with standard culture methods. The sensitivity of GeneXpert for S. aureus was 100%. Regarding a cost-effectiveness analysis, the incremental cost of using GeneXpert was of 31.1euro per patient while the incremental cost-effectiveness ratio of GeneXpert compared with blood culture alones was about 180euro per life year gained. In conclusion, GeneXpert can be used directly with blood samples obtained through infected catheters to detect S. aureus and MR-CoNS in approximately 1h after sampling. In addition, it is cost-effective especially in areas with high prevalence of staphylococcal CRB

HACEK infective endocarditis: epidemiology, clinical features outcome: A case-control study

OBJECTIVES: The study aimed to describe the epidemiology, microbiological and clinical features of a population sample of 17 patients with HACEK-IE and to compare them with matched control patients with IE caused by Viridans group Streptococci (VGS-IE). METHODS: Description of definite (14; 82.2%) and possible (3; 17.6%) HACEK-IE included in the 'Infective Endocarditis Hospital Clínic of Barcelona' (IE-HCB) database between 1979 and 2016. Furthermore, a retrospective case-control analysis was performed, matching each case to three VGS-IE controls registered in the same database during the same period of time. RESULTS: Seventeen out of 1,209 IE cases (1.3%, 95%CI 0.69-1.91) were due to HACEK group. The most frequent isolated HACEK species were Aggregatibacter spp (11; 64.7%). Intracardiac vegetations were present in 70.6% of cases. Left heart failure (LHF) was present in 29.4% of cases. Ten patients (58.8%) required in-hospital surgery and none died during hospitalization. In the case-control analysis, there was a trend toward larger vegetations in the HACEK-IE group (median (IRQ) size=11.5 (10.0-20.0) mm vs 9.0 (7.0-13.0) mm; p=0.068). Clinical manifestations, echocardiographic findings, LHF rate, systemic emboli and other complications were all comparable (p >0.05). In-hospital surgery and mortality were similar for both groups. One-year mortality was lower for HACEK-IE (1/17 vs. to 6/48, p=0.006). CONCLUSIONS: HACEK-IE represented 1.3% of all IE cases. Clinical features and outcome were comparable with the VGS-IE control group. Despite the trend to

Fosfomycin plus Beta-lactams: Synergistic Bactericidal Combinations in Methicillin-resistant (MRSA) and Glycopeptide-Intermediate Resistant (GISA) Staphylococcus aureus Experimental Endocarditis

The urgent need of effective therapies for methicillin-resistant Staphylococcus aureus (MRSA) infective endocarditis (IE) is a cause of concern. We aimed to ascertain the in vitro and in vivo activity of the older antibiotic fosfomycin combined with different beta-lactams against MRSA and glycopeptide-intermediate-resistant S. aureus (GISA) strains. Time-kill tests with 10 isolates showed that fosfomycin plus imipenem (FOF+IPM) was the most active evaluated combination. In an aortic valve IE model with two strains (MRSA-277H and GISA-ATCC 700788), the following intravenous regimens were compared: fosfomycin (2 g every 8 h [q8h]) plus imipenem (1 g q6h) or ceftriaxone (2 g q12h) (FOF+CRO) and vancomycin at a standard dose (VAN-SD) (1 g q12h) and a high dose (VAN-HD) (1 g q6h). Whereas a significant reduction of MRSA-227H load in the vegetations (veg) was observed with FOF+IPM compared with VAN-SD (0 [interquartile range [IQR], 0 to 1] versus 2 [IQR, 0 to 5.1] log CFU/g veg; P = 0.01), no statistical differences were found with VAN-HD. In addition, FOF+IPM sterilized more vegetations than VAN-SD (11/15 [73%] versus 5/16 [31%]; P = 0.02). The GISA-ATCC 700788 load in the vegetations was significantly lower after FOF+IPM or FOF+CRO treatment than with VAN-SD (2 [IQR, 0 to 2] and 0 [IQR, 0 to 2] versus 6.5 [IQR, 2 to 6.9] log CFU/g veg; P < 0.01). The number of sterilized vegetations after treatment with FOF+CRO was higher than after treatment with VAN-SD or VAN-HD (8/15 [53%] versus 4/20 [20%] or 4/20 [20%]; P = 0.03). To assess the effect of FOF+IPM on penicillin binding protein (PBP) synthesis, molecular studies were performed, with results showing that FOF+IPM treatment significantly decreased PBP1, PBP2 (but not PBP2a), and PBP3 synthesis. These results allow clinicians to consider the use of FOF+IPM or FOF+CRO to treat MRSA or GISA IE.Copyright © 2015, American Society for Microbiology. All Rights Reserved

Relationship among Streptococcus gallolyticus Subsp. gallolyticus, Enterococcus faecalis and Colorectal Neoplasms in Recurrent Endocarditis: A Historical Case Series.

Objectives: The role of colorectal neoplasms (CRN) as a common potential source of recurrent Streptococcus gallolyticus subsp. gallolyticus (SGG) and Enterococcus faecalis (EF) endocarditis remains unstudied. We aimed to investigate what proportion of episodes of recurrent endocarditis are caused by a succession of SGG and EF, or vice versa, and to assess the role of a colonic source in such recurrent episodes. Methods: we conducted a retrospective analysis of two prospective endocarditis cohorts (1979-2019) from two Spanish hospitals, providing descriptive analyses of the major features of the endocarditis episodes, colonoscopy findings, and histologic results. Results: among 1552 IE episodes, 204 (13.1%) were caused by EF and 197 (12.7%) by SGG, respectively. There were 155 episodes (10%) of recurrent IE, 20 of which (12.9%) were due to a succession of SGG/EF IE in 10 patients (the first episode caused by SGG in eight cases, and by EF in two cases). The median follow-up was 86 (interquartile range 34-156) months. In 8/10 initial episodes, the causative microorganism was SGG, and all patients were diagnosed with CRN either during the initial episode or during follow-up. During the second episode of IE or follow-up, colonoscopies revealed CRN in six patients. Conclusions: There seems to be an association between SGG and EF in recurrent endocarditis that warrants further investigation. Our findings reinforce the need for systematically performing colonoscopy in the event of endocarditis caused by both microorganisms

Effectiveness of vancomycin plus cloxacillin compared with vancomycin, cloxacillin and daptomycin single therapies in the treatment of methicillin-resistant and methicillin-susceptible Staphylococcus aureus in a rabbit model of experimental endocarditis

Objectives: To investigate if the addition of cloxacillin to vancomycin enhances the activity of both monotherapies for treating MSSA and MRSA experimental endocarditis (EE) in rabbits. Methods: Vancomycin plus cloxacillin was compared with the respective monotherapies and daptomycin. In vitro time-kill studies were performed using standard (105 cfu) and high (108 cfu) inocula of five MRSA, one glycopeptide-intermediate (GISA) and five MSSA strains. One MSSA (MSSA-678) and one MRSA (MRSA-277) strain were selected to be used in the in vivo model. A human-like pharmacokinetics model was applied and the equivalents of cloxacillin 2 g/4 h IV and daptomycin 6 mg/kg/day IV were administered. To optimize vancomycin activity, dosage was adjusted to achieve an AUC/MIC ≥400. Results: Daptomycin sterilized significantly more vegetations than cloxacillin (13/13, 100% versus 9/15, 60%; P = 0.02) and showed a trend of better activity than vancomycin (10/14, 71%; P = 0.09) and vancomycin plus cloxacillin (10/14, 71%; P = 0.09) against MSSA-678. Addition of cloxacillin to vancomycin (13/15, 87%) was significantly more effective than vancomycin (8/16, 50%; P = 0.05) and showed similar activity to daptomycin (13/18, 72%; P = 0.6) against MRSA-277. In all treatment arms, the bacterial isolates recovered from vegetations were re-tested and showed the same daptomycin susceptibility as the original strains. Conclusions: Vancomycin plus cloxacillin proved synergistic and bactericidal activity against MRSA. Daptomycin was the most efficacious option against MSSA and similar to vancomycin plus cloxacillin against MRSA. In settings with high MRSA prevalence, vancomycin plus cloxacillin might be a good alternative for empirical therapy of S. aureus IE

Time to blood culture positivity as a predictor of clinical outcomes and severity in adults with bacteremic pneumococcal pneumonia

Objectives: We aimed to investigate the association between the time to positivity of blood culture (TTP) with clinical outcome and severity of pneumococcal bacteremic pneumonia. Methods: Prospective observational study carried out in 278 hospitalized adult CAP patients with positive blood culture for Streptococcus pneumonia (2003-2015). Results: A total of 278 cases of bacteremic pneumococcal pneumonia were analyzed, median age 62 (46; 79) years. Fifty-one percent of the cases had PSI IV-V. Twenty-one (8%) died within 30-days after admission. The analysis of the TTP showed that the first quartile of the TTP (9.2h) was the best cut-off for differentiating 2 groups of patients at risk, early (TTP <9.2 h) and late (TTP ≥9.2 h) detection groups (AUC 0.66 [95% CI 0.53 to 0.79]). Early TTP was associated with a statistically significant risk of invasive mechanical ventilation (18% vs. 6%, p = 0.007), longer length of hospital stay (12 days vs. 8 days, p<0.001), higher in-hospital mortality (15% vs. 4%, p = 0.010), and 30-day mortality (15% vs. 5%, p = 0.018). After adjustment for potential confounders, regression analyses revealed early TTP as independently associated with high risk of invasive mechanical ventilation (OR 4.60, 95% CI 1.63 to 13.03), longer length of hospital stay (β 5.20, 95% CI 1.81 to 8.52), higher in-hospital mortality (OR 5.35, 95% CI 1.55 to 18.53), and a trend to higher 30-day mortality (OR 2.47, 95% CI 0.85 to 7.21) to be a contributing factor. Conclusion: Our results demonstrate that TTP is an easy to obtain surrogate marker of the severity of pneumococcal pneumonia and a good predictor of its outcome