Accuracy of procalcitonin for diagnosing peripheral blood culture contamination among patients with positive blood culture for potential contaminants.

PURPOSE: Blood culture contamination is still a frequently observed event and may lead to unnecessary antibiotic prescriptions and additional hazards and costs. However, in patients hospitalized in tertiary care, true bacteremias for pathogens that are classically considered as contaminants can be observed. We assessed the diagnostic accuracy of procalcitonin for differentiating blood culture contamination from bacteremia in patients with positive blood cultures for potential contaminants. METHODS: We carried out a retrospective, cross-sectional, observational study on consecutive patients hospitalized between January 2016 and May 2019 at the University Hospital of Nancy and who had a positive peripheral blood culture for a pathogen classically considered as a potential contaminant. RESULTS: During the study period, 156 patients were screened, and 154 were retained in the analysis. Among the variables that were significantly associated with a diagnosis of blood culture contamination in univariate analyses, four were maintained in multivariate logistic regression analysis: a number of positive blood culture bottles ≤ 2 (OR 23.76; 95% CI 1.94-291.12; P = 0.01), procalcitonin < 0.1 ng/mL (OR 14.88; 95% CI 1.62-136.47; P = 0.02), non-infection-related admission (OR 13.00; 95% CI 2.17-77.73; P = 0.005), and a percentage of positive blood culture bottles ≤ 25% (OR 12.15; 95% CI 2.02-73.15; P = 0.006). CONCLUSIONS: These data provide new evidence on the usefulness of plasma procalcitonin as a reliable diagnostic biomarker in the diagnostic algorithm of peripheral blood culture contamination among patients hospitalized in tertiary care. CLINICAL TRIAL: ClinicalTrials.gov #NCT04573894.

Infection related catheter complications in patients undergoing prone positioning for acute respiratory distress syndrome: an exposed/unexposed study.

BACKGROUND: Prone positioning (PP) is a standard of care for patients with moderate-severe acute respiratory distress syndrome (ARDS). While adverse events associated with PP are well-documented in the literature, research examining the effect of PP on the risk of infectious complications of intravascular catheters is lacking. METHOD: All consecutive ARDS patients treated with PP were recruited retrospectively over a two-year period and formed the exposed group. Intensive care unit (ICU) patients during the same period without ARDS for whom PP was not conducted but who had an equivalent disease severity were matched 1:1 to the exposed group based on age, sex, centre, length of ICU stay and SAPS II (unexposed group). Infection-related catheter complications were defined by a composite criterion, including catheter tip colonization or intravascular catheter-related infection. RESULTS: A total of 101 exposed patients were included in the study. Most had direct ARDS (pneumonia). The median [Q1-Q3] PP session number was 2 [1-4]. These patients were matched with 101 unexposed patients. The mortality rates of the exposed and unexposed groups were 31 and 30%, respectively. The incidence of the composite criterion was 14.2/1000 in the exposed group compared with 8.2/1000 days in the control group (p = 0.09). Multivariate analysis identified PP as a factor related to catheter colonization or infection (p = 0.04). CONCLUSION: Our data suggest that PP is associated with a higher risk of CVC infectious complications.

Comparison of Vitek MS and MALDI Biotyper for Identification of Actinomycetaceae of Clinical Importance.

The Vitek MS in vitro diagnostic (IVD) and MALDI Biotyper IVD systems were evaluated for the identification of 158 strains of Actinomycetaceae. Correct species-level identification rates of 60.7% and 58.2% were obtained with the Vitek MS system after direct deposit and with the MALDI Biotyper system after on-plate formic acid treatment, respectively.

A new mechanism to render clinical isolates of Escherichia coli non-susceptible to imipenem: substitutions in the PBP2 penicillin-binding domain.

OBJECTIVES: So far, two types of mechanism are known to be involved in carbapenem non-susceptibility of Escherichia coli clinical isolates: reduced outer membrane permeability associated with production of ESBLs and/or overproduction of class C ß-lactamases; and production of carbapenemases. Non-susceptibility to only imipenem observed in two clinical isolates suggested a new mechanism, described in the present study. METHODS: The ST was determined for the two isolates of E. coli (strains LSNy and VSBj), and their chromosomal region encoding the penicillin-binding domain of PBP2 was amplified, sequenced and then used for recombination experiments in E. coli K12 C600. Antibiotic MICs were determined using the Etest method. RESULTS: Strains LSNy and VSBj, which displayed ST23 and ST345, respectively, showed amino acid substitutions in their PBP2 penicillin-binding domain. Substitution Ala388Ser located in motif 2 (SXD) was common to the two strains. Two additional substitutions (Ala488Thr and Leu573Val) located outside the two other motifs were identified in strain LSNy, whereas another one (Thr331Pro) located in motif 1 was identified in strain VSBj. Recombination experiments to reproduce non-susceptibility to imipenem in E. coli K12 C600 were not successful when only the common substitution was transferred, whereas recombination with DNA fragments including either the three substitutions (strain LSNy) or the two substitutions (strain VSBj) were successful. CONCLUSIONS: Substitution of amino acids in the penicillin-binding domain of PBP2 is a new mechanism by which E. coli clinical isolates specifically resist imipenem.

Characterization of a new blaOXA-48-carrying plasmid in Enterobacteriaceae.

In this work, we characterized a new, 160-kb, blaOXA-48-harboring IncL/M-type plasmid isolated from a Klebsiella pneumoniae strain from France. Moreover, we report the transfer of a 60-kb OXA-48-encoding plasmid from Klebsiella pneumoniae to other Enterobacteriaceae in two patients.

Evaluating antibiotic stewardship and healthcare-associated infections surveillance assisted by computer: protocol for an interrupted time series study.

INTRODUCTION: Antibiotic resistance is one of the most pressing health threats that mankind faces now and in the coming decades. Antibiotic resistance leads to longer hospital stays, higher medical costs and increased mortality. In order to tackle antibiotic resistance, we will implement in our tertiary care university hospital a computerised-decision support system (CDSS) facilitating antibiotic stewardship and an electronic surveillance software (ESS) facilitating infection prevention and control activities. We describe the protocol to evaluate the impact of the CDSS/ESS combination in adult inpatients. METHODS AND ANALYSIS: We conduct a pragmatic, prospective, single-centre, before-after uncontrolled study with an interrupted time-series analysis 12 months before and 12 months after the introduction of the CDSS for antibiotic stewardship (APSS) and ESS for infection surveillance (ZINC). APSS and ZINC will assist, respectively, the antibiotic stewardship and the infection prevention and control teams of Nancy University Hospital (France). We will evaluate the impact of the CDSS/ESS on the antibiotic use in adult (≥18 years) inpatients (hospitalised ≥48 hours). The primary outcome is the prescription rate by all healthcare professionals from the hospital of all systemic antibiotics expressed in defined daily doses/1000 patients/month. Concurrently, we will assess the safety of the intervention, its impact on the appropriateness of antibiotic prescriptions and on additional precautions (isolation precautions) as recommended in guidelines, and on bacterial epidemiology (multidrug-resistant bacteria and Clostridioides difficile infections) in the hospital. Finally, we will evaluate the users' satisfaction and the cost of this intervention from the hospital perspective. ETHICS AND DISSEMINATION: The protocol has been approved by the Ethics Committee of Nancy University Hospital and registered on the ClinicalTrials platform. Results will be disseminated through conferences' presentations and publications in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT04976829.

Rapid bench identification of methicillin-sensitive and methicillin-resistant Staphylococcus aureus: A multicenter comparative evaluation of Alere PBP2a Culture Colony Test (Alere) Versus Slidex MRSA detection (bioMérieux).

Using 30 clinical isolates of Staphylococcus aureus representative of the most prevalent clones circulating in France, the performance of the Alere™ PBP2a Culture Colony Test (CCT) and the Slidex(®) MRSA detection kit (SMD) were compared in 5 different labs. CCT demonstrated better performance and was easier to conduct in routine.

Diagnostic Accuracy of Procalcitonin for Predicting Blood Culture Results in Patients With Suspected Bloodstream Infection: An Observational Study of 35,343 Consecutive Patients (A STROBE-Compliant Article).

Previous studies have suggested that procalcitonin is a reliable marker for predicting bacteremia. However, these studies have had relatively small sample sizes or focused on a single clinical entity. The primary endpoint of this study was to investigate the diagnostic accuracy of procalcitonin for predicting or excluding clinically relevant pathogen categories in patients with suspected bloodstream infections. The secondary endpoint was to look for organisms significantly associated with internationally validated procalcitonin intervals. We performed a cross-sectional study that included 35,343 consecutive patients who underwent concomitant procalcitonin assays and blood cultures for suspected bloodstream infections. Biochemical and microbiological data were systematically collected in an electronic database and extracted for purposes of this study. Depending on blood culture results, patients were classified into 1 of the 5 following groups: negative blood culture, Gram-positive bacteremia, Gram-negative bacteremia, fungi, and potential contaminants found in blood cultures (PCBCs). The highest procalcitonin concentration was observed in patients with blood cultures growing Gram-negative bacteria (median 2.2 ng/mL [IQR 0.6-12.2]), and the lowest procalcitonin concentration was observed in patients with negative blood cultures (median 0.3 ng/mL [IQR 0.1-1.1]). With optimal thresholds ranging from ≤0.4 to ≤0.75 ng/mL, procalcitonin had a high diagnostic accuracy for excluding all pathogen categories with the following negative predictive values: Gram-negative bacteria (98.9%) (including enterobacteria [99.2%], nonfermenting Gram-negative bacilli [99.7%], and anaerobic bacteria [99.9%]), Gram-positive bacteria (98.4%), and fungi (99.6%). A procalcitonin concentration ≥10 ng/mL was associated with a high risk of Gram-negative (odds ratio 5.98; 95% CI, 5.20-6.88) or Gram-positive (odds ratio 3.64; 95% CI, 3.11-4.26) bacteremia but dramatically reduced the risk of PCBCs or fungemia. In this large real-life setting experience with more than 35,000 patients, procalcitonin was highly effective at excluding bloodstream infections regardless of pathogen categories. The results from our study are limited by its cross-sectional design and deserve to be validated in prospective longitudinal studies.

Staphylococcus aureus infective endocarditis versus bacteremia strains: Subtle genetic differences at stake.

Infective endocarditis (IE)((1)) is a severe condition complicating 10-25% of Staphylococcus aureus bacteremia. Although host-related IE risk factors have been identified, the involvement of bacterial features in IE complication is still unclear. We characterized strictly defined IE and bacteremia isolates and searched for discriminant features. S. aureus isolates causing community-acquired, definite native-valve IE (n=72) and bacteremia (n=54) were collected prospectively as part of a French multicenter cohort. Phenotypic traits previously reported or hypothesized to be involved in staphylococcal IE pathogenesis were tested. In parallel, the genotypic profiles of all isolates, obtained by microarray, were analyzed by discriminant analysis of principal components (DAPC)((2)). No significant difference was observed between IE and bacteremia strains, regarding either phenotypic or genotypic univariate analyses. However, the multivariate statistical tool DAPC, applied on microarray data, segregated IE and bacteremia isolates: IE isolates were correctly reassigned as such in 80.6% of the cases (C-statistic 0.83, P<0.001). The performance of this model was confirmed with an independent French collection IE and bacteremia isolates (78.8% reassignment, C-statistic 0.65, P<0.01). Finally, a simple linear discriminant function based on a subset of 8 genetic markers retained valuable performance both in study collection (86.1%, P<0.001) and in the independent validation collection (81.8%, P<0.01). We here show that community-acquired IE and bacteremia S. aureus isolates are genetically distinct based on subtle combinations of genetic markers. This finding provides the proof of concept that bacterial characteristics may contribute to the occurrence of IE in patients with S. aureus bacteremia.

Urinary tract infections in hospitalized inflammatory bowel disease patients: a 10-year experience.

BACKGROUND: Cystitis is the most common genitourinary complication in Crohn's disease (CD). We assessed the prevalence of and risk factors for urinary tract infections (UTI) in inflammatory bowel diseases (IBD). METHODS: Among the 1173 IBD patients of the "Nancy IBD cohort" seen between January 1, 2000 and December 31, 2009, 56 hospitalized patients had 76 documented UTI. Prevalence of UTI in IBD was calculated using rates of UTI among non-IBD patients hospitalized during the same period. The cases were compared to 175 matched IBD patients without UTI hospitalized during the same period to identify risk factors for UTI. RESULTS: Prevalence of UTI was 4% in IBD patients versus 3.3% in non-IBD patients (P = 0.1). Prevalence of UTI was 4.5% and 2.1% in ulcerative colitis (UC) and CD patients, respectively (P = 0.6). Risk factors for UTI in CD patients were perianal disease (odds ratio [OR] = 2.28, 95% confidence interval [CI], 1.06-4.89; P = 0.04) and colonic disease (OR = 2.42, 95% CI, 1.05-5.58; P = 0.04). Male gender (OR = 0.38, 95% CI, 0.17-0.85, P = 0.02) and noncomplicated behavior (OR = 0.26, 95% CI, 0.11-0.60, P = 0.002) were protective factors against UTI in CD. In UC patients, age over 40 years (OR = 9.59, 95% CI, 1.93-47.74; P = 0.006) and disease duration over 11 months (OR = 10.77, 95% CI, 1.68-68.89, P = 0.01) were risk factors for UTI. Male gender was negatively associated with UTI (OR = 0.04, 95% CI, 0.01-0.36, P = 0.00006). CONCLUSIONS: Hospitalized IBD patients are not at increased risk of UTI. Risk factors for UTI include perianal disease and colonic disease in CD and age and longer disease duration in UC.

Evaluation of the duration of vanA vancomycin-resistant Enterococcus faecium carriage and clearance during a large-scale outbreak in a region of eastern France.

A monthly follow-up evaluation of vancomycin-resistant Enterococcus-colonized patients conducted during an outbreak in France revealed that carriage can persist for an extended period. Recurrence was observed despite as many as 3 negative cultures. As a result, we propose another definition for VRE clearance.

Influence of preoperative antibiotherapy on valve culture results and outcome of endocarditis requiring surgery.

OBJECTIVES: Although medical-surgical therapy can reduce mortality in patients with infective endocarditis (IE), the optimal timing of surgery remains controversial. We evaluated the influence of preoperative antimicrobial therapy duration on positivity of valve culture and outcome. METHODS: We retrospectively studied 94 consecutive patients admitted in our intensive care unit (ICU) and operated before completion of standard antimicrobial therapy. RESULTS: Of 90 valves cultured, 46 were positive. In univariate analysis, time between diagnosis and surgery as well as duration of adequate therapy before surgery was shorter in patients with positive valve cultures as compared to those with negative cultures. A preoperative duration of adequate therapy > or =7 days was strongly associated with negative valve cultures (76% vs. 22%, P<0.001). Logistic regression analysis identified duration of preoperative adequate antimicrobial therapy as an independent risk factor for positive valve culture. However, there was no significant difference between patients with positive or negative valve culture regarding the occurrence of complications, ICU and hospital length of stay, hospital and long-term mortality, endocarditis relapse and reinfection, as well as treatment failure. CONCLUSIONS: Although the duration of adequate preoperative antimicrobial therapy is associated with the positivity of valve culture, the latter factor does not influence short- or long-term outcome.