Clinical evaluation of BacT/Alert FA plus and FN plus bottles compared with standard bottles

Bacterial species in cord blood and their significance in the context of clinical use

Approximately 90 % of infants born before 28 full weeks(extremely-preterm-infants) receive erythrocyte transfusions in early life. Umbilical cord blood(UCB) has been investigated as an alternative source for erythrocyte transfusions to preterm neonates. This retrospective study aimed to compile/evaluate spectrum of bacteria groups/species intermittently detected in processed UCB at National-Swedish-Cord blood bank, (NS-CBB) during the years 2008-2020. Consecutive data from the years 2008-2020 were investigated. UCB from healthy newborns born after 37 full weeks of gestation was collected following clamping of cord (1 min) through cannulation of umbilical vein(vaginal-and C-section-deliveries). In total, 5194 cord blood units (UCBUs) that met NS-CBB-guidelines for total nucleated-cell-content(TNC) were manufactured from 8875 collections. Of 5194 UCBUs,77,6 % were from vaginal-and 22,4 % from C-section deliveries.Samples(10 mL) were collected from surplus eryhtrocyte fraction post-processing(n = 5194), transferred into BACT/ALERT® aerobic/anaerobic culture flasks and monitored 10 days using BACT/ALERT®-3D-Microbial-Detection-Systems. Positive samples were subcultured and typed for bacterial groups and/or species. Out of 5194 processed sampled UCB units,186 (3,6 %) were discarded due to positive sterility tests, 92 % were detected in samples from vaginal-deliveries and 8 % from C-section-deliveries. In all,16 different groups of bacteria and 27 species were identified. Common bacterial/groups and species were anaerobe gram-negative rods(n = 28),coagulase-negative-staphylococci(n = 21),gram-positive rods(n = 21),anaerobe-gram-positive cocci(n = 20) and viridans-streptococci(n = 13). Extracted from these results,in positive samples(n = 13) from C-section deliveries, bacteria were found:viridans-streptococci(n = 7),Aerococcus-urinae(n = 1), Staphylococcus lugdunensis(n = 1),other coagulase-negative staphylococci(n = 1) or a mix of aerobic/anaerobic bacteria(n = 3). Our results are in alignment with previously published contamination rates in processed UCBUs. Still, results point towards importance of strict microbial monitoring when manufacturing UCBUs to achieve patient-safe- products for stem-cell transplantation/transfusion.

High burden of ESBL and carbapenemase-producing gram-negative bacteria in bloodstream infection patients at a tertiary care hospital in Addis Ababa, Ethiopia

BACKGROUND

Bloodstream infection due to beta-lactamase and carbapenemase-producing gram-negative bacteria poses a substantial challenge to the effectiveness of antimicrobial treatments. Therefore, this study aimed to investigate the magnitude of beta-lactamase, carbapenemase-producing gram-negative bacteria, and associated risk factors of bloodstream infections in patients at a tertiary care hospital, in Addis Ababa, Ethiopia.

METHODS

An institutional-based cross-sectional study was conducted with convenience sampling techniques from September 2018 to March 2019. Blood cultures were analyzed from 1486 bloodstream infection suspected patients across all age groups. The blood sample was collected using two BacT/ALERT blood culture bottles for each patient. Gram stain, colony characteristics, and conventional biochemical tests were used to classify the gram-negative bacteria at the species level. Antimicrobial susceptibility testing was carried out to screen beta-lactam and carbapenem drug-resistant bacteria. The E-test was conducted for extended-spectrum-beta-lactamase and AmpC-beta-lactamase-producers. A modified and EDTA-modified carbapenem inactivation method was conducted for carbapenemase and metallo-beta-lactamases producers. Data collected using structured questionnaires and medical records were reviewed, encoded, and cleaned using EpiData V3.1. software. The cleaned data were exported and analyzed using SPSS version 24 software. Descriptive statistics and multivariate logistic registration models were used to describe and assess factors associated with acquiring drug-resistant bacteria infection. A p-value <0.05 was considered statistically significant.

RESULT

Among 1486 samples, 231 gram-negative bacteria were identified; of these, 195(84.4%) produce drug-hydrolyzing enzymes, and 31(13.4%) produce more than one drug-hydrolyzing enzyme. We found 54.0% and 25.7% of the gram-negative bacteria to be extended-spectrum-beta-lactamase and carbapenemase-producing, respectively. The extended-spectrum-beta-lactamase plus AmpC-beta-lactamase-producing bacteria account for 6.9%. Among the different isolates Klebsiella pneumonia 83(36.7%) was the highest drug-hydrolyzing enzyme-producing bacteria. Acinetobacter spp 25(53.2%) was the most carbapenemase producer. Extended-spectrum-beta-lactamase and carbapenemase-producing bacteria were high in this study. A significant association between age groups and extended-spectrum-beta-lactamase producer bacterial infection was seen, with a high prevalence in neonates (p = <0.001). Carbapenemase showed a significant association with patients admitted to the intensive care unit (p = 0.008), general surgery (p = 0.001), and surgical intensive care unit (p = 0.007) departments. Delivery of neonates by caesarean section, and insertion of medical instruments into the body were exposing factors for carbapenem-resistant bacterial infection. Chronic illnesses were associated with an extended-spectrum-beta-lactamase-producing bacterial infection. Klebsiella pneumonia and Acinetobacter species showed the greatest rates of extensively drug-resistant (37.3%) and pan-drug-resistance (76.5%), respectively. According to the results of this study, the pan-drug-resistance prevalence was found to be alarming.

CONCLUSION

Gram-negative bacteria were the main pathogens responsible for drug-resistant bloodstream infections. A high percentage of extended-spectrum-beta-lactamase and carbapenemase-producer bacteria were found in this study. Neonates were more susceptible to extended-spectrum-beta-lactamase and AmpC-beta-lactamase-producer bacteria. Patients in general surgery, caesarean section delivery, and intensive care unit were more susceptible to carbapenemase-producer bacteria. The suction machines, intravenous lines, and drainage tubes play an important role in the transmission of carbapenemase and metallo-beta-lactamase-producing bacteria. The hospital management and other stakeholders should work on infection prevention protocol implementation. Moreover, special attention should be given to all types of Klebsiella pneumoniae and pan-drug resistance Acinetobacter spp transmission dynamics, drug resistance genes, and virulence factors.

Antimicrobial Resistance and Associated Risk Factors of Gram-Negative Bacterial Bloodstream Infections in Tikur Anbessa Specialized Hospital, Addis Ababa

Background

Bloodstream infections (BSIs) are significant causes of morbidity and mortality in Ethiopia and worldwide. Alarming is the rapid global spread of antimicrobial resistance (AMR) in bacteria.

Objective

To determine the microbial profile, antimicrobial susceptibility pattern, and associated risk factors for bloodstream infections in Tikur Anbessa Specialized Hospital (TASH) Addis Ababa Ethiopia.

Methods

A cross-sectional study was conducted between September 2018 and March 2019. Blood collected twice from each septicemia suspected patient were processed following standard bacteriological procedures. AST was performed by using the disk diffusion test according to CLSI 2017 and 2018 guidelines. Data captured in Epidata were cleaned and analyzed by SPSS version 21 software.

Results

The prevalence of BSI was 28.06% and a higher proportion of pathogene detected were gram-negative bacteria (GNB) (54.5%) and gram-positive bacteria (GPB) (45.43%). The most abundant bacterial species were Klebsiella pneumoniae 17.6%, CoNS 15.2%, and Acinetobacter spp 11.0%. Culture positivity was associated with age below 6 years, neonates AOR p=<0.001, infants AOR p=<0.001, Pre-school P=0.002, ICU admission COR p=<0.001, length of admission >5 days COR P=0.016, temperature greater than 38°C, AOR p=0.013, instrument usage during medical care AOR, p=<0.001, chronic illness AOR p=0.027, and neonatal incubation AOR p=0.013. GNB average drug resistance rate was 57.9% of the commonly used antibiotics and the most efficient and inefficient drugs were amikacin (10.8%) and ampicillin (94.6%). The gram-negative isolates showed a 95.3% rate of multi-drug resistance; and MDR, XDR, and PDR were observed at 55.8%, 32.2%, and 7.3%, of isolates respectively. This finding shows children especially neonates were highly affected by drug resistant BSI.

Conclusion

Pediatric patients and ICU patients are more affected by BSI, and drug-resistant bacteria are a major problem. Therefore, appropriate intervention approaches need to be implemented.

Association between the point-rating system used for oral health and the prevalence of Gram-negative bacilli in hematological inpatients: A retrospective cohort study

Gram-negative bacteremia is a major cause of death among hematology inpatients who require heavy-dose chemotherapy and hematopoietic stem cell transplantation. Gram-negative bacillus (GNB) is more likely to be detected when the oral health is poor. However, there is a dearth of studies on the relationship between oral assessment and prevalence of GNB in hematology inpatients.This retrospective study aimed to evaluate the relationship between the original point-rating system for oral health examinations (point-oral exam) and the prevalence of GNB in hematology inpatients at the hematology ward of the Yamanashi University Hospital. GNB was detected by cultivating samples from the sputum and blood of each patient.A total of 129 subjects underwent a medical checkup and point-oral exam. The sputum and blood culture results of 55 patients were included in this study. The total points of patients positive for GNB (n = 25, 45.5%) were significantly higher than those who were negative for GNB (total score: median, 25th, 75th, percentile; 6 [4, 7] vs 2 [1, 4]; P = .00016). Based on the receiver operating characteristic analysis, a cutoff score of 5 proved to be most useful to detect GNB.An oral evaluation with a cutoff value of 5 or higher in the point-oral exam might indicate the need for a more thorough oral management to prevent the development of systemic infections from GNB.

Seasonal variations in blood culture numbers and time to positivity and potential impact of reducing incubation periods

Patients with viral respiratory infections often present symptoms compatible with bloodstream infections. Consequently, the winter period commonly associated with epidemic respiratory illnesses shows an increase in the number of blood cultures (BC) and to occasional saturation of automated BC systems. Here, we explored the seasonal variations in BC samples and the potential impact of shortening the incubation time of BC when automated BC systems are close to saturation. A retrospective study was conducted during a 3-year period in 4 hospitals located in the Paris region, France. All aerobic and anaerobic bottles were included, except pediatric bottles and those sampled for suspicion of endocarditis. The number of BC bottles collected during the winter period was compared to the annual baseline. All bottles positive after a 4-day incubation were analyzed regarding clinical and microbiological findings. The number of BC bottles was significantly higher during the winter periods, compared to the annual baseline (up to 14%). A total of 292,349 BC bottles were analyzed with 23,363 (8.0%) positive, including 236 (1%) after a 4-day incubation. Of these 236 bottles, 76 (64.8%) were positive with a contaminant, 78 (33.1%) with a clinically significant microorganism identified for the same patient in the previous 4 days, and only 5 (2.1%) with a clinically significant microorganism not previously identified. Winter periods were associated with a significant increase in BC samples. Shortening the incubation time of BC bottles from 5 to 4 days seems a relevant option when automated BC systems are close to saturation.

Clinical evaluation of FAPlus/FNPlus bottles compared with the combination of SA/SN and FA/FN bottles in the BacT/Alert blood culture system

Background : The comparison of the performance of FAPlus/FNPlus bottles and combination of SA/SN and FA/FN bottles is not yet reported. Methods : We used human blood samples to investigate microorganism detection rates and the time to positivity (TTP) in a before-vs.-after study (a combination of SA/SN and FA/FN bottles from September 2012 to August 2013 vs. FAPlus/FNPlus bottles from September 2013 to August 2014). Results : The microorganism detection rate was significantly higher in the later period than in the earlier period (11.2% vs. 9.6%, P < 0.001), particularly for Enterococcus and Streptococcus species, nonfermentative Gram-negative bacilli, and Helicobacter cinaedi. TTP for pathogens was longer when FAPlus/FNPlus bottles were used than when a combination of SA/SN and FA/FN bottles was used (14.9 vs. 13.3 h, P = 0.014), particularly, in the case of Gram-negative bacilli including Escherichia coli. Conclusion : The microorganism detection rate was improved with the use of FAPlus/FNPlus bottles compared with the combination of SA/SN and FA/FN bottles ; however, FAPlus/FNPlus bottles seemed to be inferior to SA/SN and FA/FN bottles in terms of TTP. J. Med. Invest. 67 : 90-94, February, 2020.

Clinical Profile and the Role of Rapid Serological Tests: Typhifast IgM and Enterocheck WB in the Diagnosis of Typhoid Fever

Introduction

During identification and diagnosis, typhoid fever (TF) causes various issues such as nonspecific symptoms and nontyphoidal Salmonella-associated febrile diseases. Accurate identification and diagnosis are still a substantial concern. The current study was undertaken to study the clinical profile of TF and the role of Typhifast IgM and Enterocheck WB in early diagnosis.

Materials and methods

Clinically suspected TF patients (121) were included in the study. Patients with antibiotic history during the period of febrile illness were excluded. The diagnosis was confirmed with blood culture test. Widal test and two new rapid serological tests: Typhifast IgM and Enterocheck WB were performed. The outcomes were compared with blood culture-confirmed cases to derive the sensitivity and specificity of the diagnostic tests. The clinical characteristics were compared with diagnostic tests using Chi-square test.

Results

The most common presentations of TF were fever, chills, vomiting, abdominal pain, anorexia, constipation, and diarrhea. Among the 121 clinically suspected TF patients, 67 had positive blood culture tests for Salmonella typhi. The Typhifast IgM and Enterocheck WB showed sensitivity of 97.01% and 68.52%, respectively. Specificity was also more with Typhifast IgM (85.07%) than with Enterocheck WB (62.96%). When tests were used in parallel combination, 97.01% sensitivity was attained, while the specificity dropped to 46.30%. When used in serial combination, sensitivity of 85.07% and specificity of 85.19% were observed.

Conclusion

Stepladder fever, abnormal serum glutamic oxaloacetic transaminase (SGOT), and abnormal albumin are associated with blood culture, Typhifast IgM, and Enterocheck WB tests. Rapid serological tests might assist in accurate and early identification of TF.

How to cite this article

Bhume RJ, Babaliche P. Clinical Profile and the Role of Rapid Serological Tests: Typhifast IgM and Enterocheck WB in the Diagnosis of Typhoid Fever. Indian J Crit Care Med 2020;24(5):307–312.

A comparative evaluation of BACT/ALERT FA PLUS and FN PLUS blood culture bottles and BD BACTEC Plus Aerobic and Anaerobic blood culture bottles for antimicrobial neutralization

The performance of BACT/ALERT FA and FN PLUS (FA PLUS and FN PLUS) blood culture bottles with the BACT/ALERT VIRTUO (bioMérieux, Inc., Durham, NC) and BD BACTEC Plus Aerobic and Anaerobic (BD Aerobic and BD Anaerobic) blood culture bottles with the BD BACTEC FX (BD Diagnostics, Sparks, MD) for antimicrobial neutralization at peak serum concentration was evaluated. The following antibiotic agents and microbial strains were used: ampicillin, cefepime, cefotaxime, gentamicin, levofloxacin, meropenem, piperacillin-tazobactam, and vancomycin; methicillin-sensitive Staphylococcus aureus, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Bacteroides fragilis. The detection rate of FA PLUS bottles was 69.1% (259/375) and that of BD Aerobic bottles was 75.5% (283/375) (p = 0.050). In the case of anaerobic culture, the overall detection rate of FN PLUS bottles was 77.0% (231/300) and that of BD Anaerobic bottles was 71.3% (214/300) (p = 0.113). The time to detection (TTD) from aerobic culture was 2.8 h shorter in FA PLUS bottles (12.4 h) compared to BD Aerobic bottles (15.2 h) (p < 0.001). And the TTD from anaerobic culture was 1.6 h shorter in FN PLUS bottles (18.1 h) compared to BD Anaerobic bottles (19.7 h) (p = 0.061). The FA PLUS bottles exhibited a lower detection rate compared to BD Aerobic bottles, while FN PLUS bottles showed a higher detection rate compared to BD Anaerobic bottles. The BACT/ALERT VIRTUO system exhibited shorter TTD compared to the BD BACTEC FX system for both aerobic and anaerobic cultures.

Critical factors in the recovery of pathogenic microorganisms in blood

BACKGROUND

The critical factors for optimal recovery of microbial pathogens from blood are not only the basis for how we perform blood cultures on a daily basis, but are also important for development of all current blood-culture systems. Because much of this research was conducted and published between 1975 and 2010 there is a general sense that many physicians and scientists may not be familiar with it, but it is critical for performing and interpreting blood cultures.

OBJECTIVES

To review the critical factors in the laboratory recovery and isolation of pathogenic microorganisms in blood.

SOURCES

Literature review of published papers, select reviews and updated guidelines.

CONTENT

This review focuses on the critical factors that affect the recovery isolation of pathogenic microorganisms from individuals with bloodstream infections. Contemporary blood-culture systems, and current methods for blood-culture collection, have been designed to incorporate these critical factors so as to optimize recovery and isolation of pathogens while minimizing contamination.

IMPLICATIONS

It is important for microbiologists and practitioners to understand how and why these critical factors affect current blood-culture practices to improve patient management. Future research should emphasize which of these critical factors will still play a role in the era of molecular diagnostic tests, which will no longer be relevant, and which new critical factors have yet to be defined.

Influence of a resin-based blood culture medium on the time to clearance of methicillin-susceptible Staphylococcus aureus bloodstream infection - A retrospective cohort study

We evaluated the improved sensitivity and time to detection of new resin-based blood culture (BC) media in Staphylococcus aureus bloodstream infection. We observed a significantly longer duration of bacteremia and shorter time to detection compared to traditional charcoal-based BC media, which may influence diagnostic work-up and treatment duration.

In Vitro Evaluation of BacT/Alert FA Blood Culture Bottles and T2Candida Assay for Detection of Candida in the Presence of Antifungals

The T2Candida assay is a novel, non-culture-based assay for the diagnosis of candidemia directly from whole blood. The impact of antifungals on the performance of the T2Candida assay and blood culture bottles has not been well described. In this study, the performance of the T2Candida assay was compared to that of blood culture in detecting Candida spp. in spiked blood cultures with or without the presence of antifungals. Clinical bloodstream isolates of Candida spp. were inoculated into human whole blood at low (1 to 5 cells/ml) and high (10 to 50 cells/ml) concentrations with or without the presence of caspofungin and fluconazole. Time to detection (TTD) was assessed for prepared samples using BacT/Alert FA aerobic blood culture bottles or the T2Candida assay. In the absence of antifungals, T2Candida assay sensitivity was comparable to that of blood culture at both the low inoculum and the high inoculum (95% versus 97.5% and 100% versus 100%, respectively) and the assay had an average TTD that was significantly shorter (5.1 h versus 27.2 to 30 h, respectively). Neither caspofungin nor fluconazole was observed to impact the sensitivity or TTD of the T2Candida assay, while fluconazole reduced the overall blood culture sensitivity by 7.5% to 12.5% (at the low inoculum and high inoculum, respectively) and significantly increased the TTD of Candida albicans, C. tropicalis, and C. parapsilosis by 14.8 to 67 h. Neither caspofungin nor fluconazole impacted the performance of the T2Candida assay in vitro, and the assay may be useful for the diagnosis of candidemia in patients receiving antifungal therapy.

Infective endocarditis in Western Norway: a 20-year retrospective survey

BACKGROUND

To investigate epidemiological trends of infective endocarditis (IE) in western Norway a retrospective study was performed.

METHODS

Characteristics of 706 IE admissions from 1996 to 2005 and 2006 to 2015 were analysed and compared using the Chi-square test for categorical variables and the t-test for age. Survival was analysed by multiple Cox regression and reported by the hazard ratio (HR).

RESULTS

Mean annual incidence rates increased from 4.6 to 7.4 per 100,000 inhabitants (rate ratio: 1.97, 95% confidence interval: 1.52-2.56, p < .001). Non-viridans streptococci, enterococci and Staphylococcus aureus (S. aureus), were all independently associated with increased mortality. The frequency of IE caused by enterococci increased from 3.7 to 13.0% (p < .001). The proportion of intravenous drug users (IVDU) increased from 16.5 to 23.5% (p = .015) and had increasing aortic valve involvement (p = .023). Prosthetic valve endocarditis (PVE) constituted 30% of IE cases in both decades with biological PVE increasing from 9.4 to 22.1% (p < .001) and mechanical PVE decreasing from 18.7 to 8.9% (p < .001). In the last decade, valve replacement surgery was performed in 37.6% of the patients, of which 85.5% received a bioprosthesis.

CONCLUSIONS

The incidence of IE increased significantly. Non-viridans streptococci, enterococci and S. aureus were all significantly associated with increased mortality. The increased number of enterococcal IE and the increased number of IVDUs with left-sided IE constituted new challenges. Biological implants were preferred in a majority of patients requiring surgery.

Performance of the BacT/Alert Virtuo Microbial Detection System for the culture of sterile body fluids: prospective multicentre study

OBJECTIVES

Continuous monitoring blood culture systems are commonly used for sterile body fluid cultures. In this multicentre study, we evaluated the performance of the new-generation BacT/Alert Virtuo system compared to the BacT/Alert 3D and conventional culture for the recovery of microorganisms from sterile body fluids.

METHODS

Peritoneal, cerebrospinal, pericardial, pleural and synovial fluids from adult patients submitted for culture were collected from three different centres. Specimens were inoculated into two bottles of the same bottle type (SA, SN, FA Plus or FN Plus) in equal volumes for simultaneous incubation in the Virtuo and 3D instruments. Each specimen was also Gram stained and seeded to solid media.

RESULTS

A total of 811 specimens were inoculated to 1257 bottle pairs. The Virtuo and 3D showed equivalent recovery of clinically significant microorganisms (127/155, 81.9%, vs. 126/155, 81.3%, respectively). Solid media cultures recovered fewer pathogens than either continuous monitoring system (95/155, 61.3%, p <0.001), including significantly fewer Enterobacteriaceae and enterococci. The Virtuo was significantly faster than the 3D in median time to detection of isolates from the same specimen (12.5 (range, 2.8-101.5) hours vs. 15.5 (range, 4.3-78.5) hours, p <0.001). Direct specimen Gram stain detected the eventual pathogen in 30 (26.1%) of 115 significant positive specimens.

CONCLUSIONS

The BacT/Alert Virtuo system was equivalent to the 3D system in organism recovery from sterile body fluid culture but showed faster detection of growth as a result of design enhancements.

Biochips for Direct Detection and Identification of Bacteria in Blood Culture-Like Conditions

Bloodstream bacterial infections are life-threatening conditions necessitating prompt medical care. Rapid pathogen identification is essential for early setting of the best anti-infectious therapy. However, the bacterial load in blood samples from patients with bacteremia is too low and under the limit of detection of most methods for direct identification of bacteria. Therefore, a preliminary step enabling the bacterial multiplication is required. To do so, blood cultures still remain the gold standard before bacteremia diagnosis. Bacterial identification is then usually obtained within 24 to 48 hours -at least- after blood sampling. In the present work, the fast and direct identification of bacteria present in blood cultures is completed in less than 12 hours, during bacterial growth, using an antibody microarray coupled to a Surface Plasmon Resonance imager (SPRi). Less than one bacterium (Salmonella enterica serovar Enteritidis) per milliliter of blood sample is successfully detected and identified in blood volumes similar to blood tests collected in clinics (i.e. several milliliters). This proof of concept demonstrates the workability of our method for human samples, despite the highly complex intrinsic nature of unprocessed blood. Our label-free method then opens new perspectives for direct and faster bacterial identification in a larger range of clinical samples.

Performance of two blood culture systems to detect anaerobic bacteria. Is there any difference?

We studied the performance characteristics of two blood culture (BC) bottles/systems, (i) BacT/ALERT-FN Plus/3D (bioMérieux, Marcy l'Étoile, France) and (ii) BACTEC-Lytic/9000 (Becton Dickinson, Sparks, USA) for detection of growth and time-to-positivity (TTP) against a balanced and diverse collection of anaerobic bacterial strains (n = 48) that included reference strains (n = 19) and clinical isolates (n = 29) of 32 species (15 Gram-negative and 17 Gram-positive). Standard suspension of bacteria was inoculated to each bottle in duplicates and incubated in the corresponding system. Overall, 62.5% (n = 30) of strains were detected by both BC bottle types. Comparing the two, 70.8% (n = 34) and 79.2% (n = 38) of strains were detected by BacT/ALERT-FN Plus and BACTEC-Lytic bottles, respectively (p = 0.38). Among Gram-negative anaerobes (n = 25) the detection rate was 76.0% (n = 19) vs. 92.0% (n = 23) (p = 0.22), respectively. Among Gram-positive anaerobes (n = 23) the detection rate was 65.2% (n = 15) in both bottles (p = 1). The average TTP per bottle was calculated only for the strains detected by both systems (n = 30) and was 40.85 h and 28.08 h for BacT/ALERT-FN Plus and BACTEC-Lytic, respectively (p < 0.001). The mean difference was 12.76 h (95% CI: 6.21-19-31 h). Six anaerobic strains were not detected by any system, including Gram-negative Porphyromonas gingivalis, and five Gram-positive strains: Finegoldia magna, Peptostreptococcus anaerobius, Propionibacterium acnes, Clostridium novyi and Clostridium clostridioforme. Furthermore, Eggerthella lenta and Prevotella bivia were detected only by BacT/ALERT-FN Plus, while Prevotella disiens and Prevotella intermedia were detected only by BACTEC-Lytic bottles. There were no major differences in detection rate among clinical and reference strains. Anaerobic bacteria represent a minority of BC isolates, however, far from ideal detection rate was observed in this study for both tested bottle/system combinations. Nevertheless, in those cases where both gave positive signal, BACTEC-Lytic was superior to BacT/ALERT FN Plus with 12.76 h shorter mean TTP. Improvements of media in blood culture bottles available for detection of anaerobes are warranted.

Prospective study of the clinical performance of three BACTEC media in a modern emergency department: Plus Aerobic/F, Plus Anaerobic/F, and Anaerobic Lytic/F

The performance of 3 blood culture bottles (BACTEC Plus Aerobic/F, Plus Anaerobic/F, and Anaerobic Lytic/F) were analyzed with clinical specimens collected from 688 Emergency Department patients. A total of 270 strains belonging to 33 species were identified, with E. coli and S. aureus as the most frequently detected. Overall recovery rate (RR) of bacteria and yeast was equivalent in the Plus Aerobic/F vials (208 of 270 isolates; 77.0%) and Anaerobic Lytic/F vials (206 isolates; 76.3%) and significantly better than in the Plus Anaerobic/F vials (189 isolates; 70.0%). Median time to detection (TTD) was earliest with the Anaerobic Lytic/F vials (12.0h) compared with the Plus Aerobic/F (14.6h) and Plus Anaerobic/F vials (15.4h). Positivity rate (PR) was similar for Anaerobic Lytic/F vials (76.9%) and Plus Aerobic/F vials (76.5%), but better if compared with Plus Anaerobic/F vials (69.4%). The PR and TTD for the combination of Plus Aerobic/F with Anaerobic Lytic/F (94.5% and 12.3h, respectively) was significantly better than with Plus Aerobic/F with Plus Anaerobic/F (87.8% and 14.1h).

The Performance of the Four Anaerobic Blood Culture Bottles BacT/ALERT-FN, -FN Plus, BACTEC-Plus and -Lytic in Detection of Anaerobic Bacteria and Identification by Direct MALDI-TOF MS

Detection and identification of anaerobic bacteria in blood cultures (BC) is a well-recognized challenge in clinical microbiology. We studied 100 clinical anaerobic BC isolates to evaluate the performance of BacT/ALERT-FN, -FN Plus (BioMérieux), BACTEC-Plus and -Lytic (Becton Dickinson BioSciences) BC bottles in detection and time to detection (TTD) of anaerobic bacteria. BACTEC Lytic had higher detection rate (94/100, 94%) than BacT/ALERT FN Plus (80/100, 80%) (p<0.01) in the studied material. There was no significant difference in detection of anaerobic bacteria among the remaining bottle types. The 67 anaerobic bacteria that signalled positive in all four bottle types were analyzed to compare the time to detection (TTD) and isolates were directly identified by MALDI-TOF MS. There was a significant difference in TTD among the four bottle types (p<0.0001). The shortest median TTD was 18 h in BACTEC Lytic followed by BacT/ALERT FN (23.5 h), BACTEC Plus (27 h) and finally BacT/ALERT FN Plus (38 h) bottles. In contrast, MALDI-TOF MS performed similarly in all bottle types with accurate identification in 51/67 (76%) BacT/ALERT FN, 51/67 (76%) BacT/ALERT FN Plus, 53/67 (79%) BACTEC Plus and 50/67 (75%) BACTEC Lytic bottles. In conclusion, BACTEC Lytic bottles have significantly better detection rates and shorter TTD compared to the three other bottle types. The anaerobic BC bottles are equally suitable for direct MALDI-TOF MS for rapid and reliable identification of common anaerobic bacteria. Further clinical studies are warranted to investigate the performance of anaerobic BC bottles in detection of anaerobic bacteria and identification by direct MALDI-TOF MS.

Performance of BacT/Alert resin-based FN plus bottles compared with BacT/Alert charcoal-based FN bottles for the detection of anaerobes in experimentally seeded blood cultures

Recently new resin-based BacT/Alert FAN Plus bottles containing antibiotic-binding polymeric beads, were introduced as an improvement of the charcoal-based FAN bottles for the recovery of bacteria and fungi. To assess the performance of the novel anaerobic FN plus bottles in the detection of anaerobic organisms, we compared the detection rate and the time to detection (TTD) in spiked resin-based FN Plus bottles and charcoal-based FN bottles. The bottles were experimentally seeded with reference strains or clinical strains collected from positive blood cultures. Five reference strains and fifty-five clinically significant anaerobic isolates were investigated, of which 91% (61/67) showed growth in both types of bottles within an incubation time of 5 days. A significant prolonged median TTD of 45 h for anaerobic microorganisms was observed in the resin-based bottles versus 29 h in the charcoal-based bottles (P < 0.0001). Bacteroides spp., associated with higher virulence and higher mortality rates in bloodstream infections, were detected faster in the charcoal-based bottles as compared to the resin-based bottles. In conclusion recently improved resin FN bottles showed a significantly increased median TTD for the recovery of anaerobic isolates.

The SUCCESS model for laboratory performance and execution of rapid molecular diagnostics in patients with sepsis

Successful performance and execution of rapid diagnostics in a clinical laboratory hinges heavily on careful validation, accurate and timely communication of results, and real-time quality monitoring. Laboratories must develop strategies to integrate diagnostics with stewardship and evidence-based clinical practice guidelines. We present a collaborative SUCCESS model for execution and monitoring of rapid sepsis diagnostics to facilitate timely treatment. Six months after execution of the Verigene Gram-Positive Blood Culture (BC-GP) and the AdvanDx PNA-FISH assays, data were collected on 579 and 28 episodes of bacteremia and fungemia, respectively. Clinical testing was executed using a SUCCESS model comprising the following components: stewardship, utilization of resources, core strategies, concierge services, education, support, and surveillance. Stewardship needs were identified by evaluating the specialty services benefiting from new testing. Utilization of resources was optimized by reviewing current treatment strategies and antibiogram and formulary options. Core strategies consisted of input from infectious disease leadership, pharmacy, and laboratory staff. Concierge services included automated Micro-eUpdate and physician-friendly actionable reports. Education modules were user-specific, and support was provided through a dedicated 24/7 microbiology hotline. Surveillance was performed by daily audit by the director. Using the SUCCESS model, the turnaround time for the detailed report with actionable guidelines to the physician was ∼3 hours from the time of culture positivity. The overall correlation between rapid methods and culture was 94% (546/579). Discrepant results were predominantly contaminants such as a coagulase-negative staphylococci or viridans streptococci in mixed cultures. SUCCESS is a cost-effective and easily adaptable model for clinical laboratories with limited stewardship resources.

High medical impact of implementing the new polymeric bead-based BacT/ALERT® FAPlus and FNPlus blood culture bottles in standard care

Blood culture (BC) efficiency is critical for the diagnosis of bloodstream infection (BSI). We evaluated the impact on standard care of implementing the new BacT/ALERT® FAPlus and FNPlus BC bottles containing antibiotic-binding polymeric beads. We measured positivity rates and time to detection (TTD) during the first 10 months of implementation (PF) and during the previous 10-month period (PS) during which we were using standard aerobic (SA) or standard anaerobic (SN) BC bottles. For each period, the same number of consecutive patients (n = 3,918) was included. Per patient, a median of 1 BC set (1 aerobic and 1 anaerobic bottles) has been sampled. A higher positivity rate was measured during PF than PS when counting per BC bottle (7.0 % vs 5.8 % with 1,456 and 1,237 positive bottles respectively, P < 0.0001) and per BC set (9.6 % vs 7.8 % with 995 and 832 positive BC sets respectively, P < 0.0001). In PF, an increased number of cases due to staphylococci (P < 0.0001) and to Gram-negative bacilli (P < 0.005) was observed, whereas the contamination rate was similar during the two periods (2.4 % of BC sets in PF and 2.3 % in PS). Although antibiotic consumption and medical activity were similar during the two periods, BSI case detection increased from 2.2 to 2.6 per 1,000 hospital-days, especially in intensive care units (ICU; 35.1 to 55.7). Mean TTD for pathogenic microorganisms was significantly shorter in PF than in PS (15.5 h vs 18.0 h, P < 0.01). In conclusion, the use of the new FAPlus/FNPlus BC bottles improved the diagnosis of bacteremia in our hospital, especially in ICU patients.

Evaluation of a new protocol for sterility controls of corneal culture medium

Careful testing for microbial contamination is essential for corneal transplants. Sterility tests are performed on the antibiotics containing culture medium leaving the problem that antibiotics might compromise the test results. In this study a protocol for the application of the automated BacT/Alert system for sterility testing of corneal cell culture medium was examined. Corneal culture medium in combination with an antibiotics degrading enzyme were injected in resin containing test bottles of the BacT/Alert system named FA plus (intended for aerobic microorganisms) or FN plus (intended for anaerobic microorganisms) depending on their aerobic or anaerobic nature. Additionally i-FA plus(aerobic test bottle for industrial use) bottles were used. Microbial test strains on the basis of the European Pharmacopaea (Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, Aspergillus brasiliensis and Clostridium sporogenes) with the addition of Propioniobacterium acnes were added to the test bottles. The bottles were incubated at two different temperatures for 14 days. The time to detection (TTD) was monitored for each bottle. Growth of the test strains except European Pharm was detected in the FA and FN Plus bottles. The TTD for the strains was 44 ± 1.5 h (P. aeruginosa), 57.7 ± 2.2 h (B. subtilis), 56 ± 1 h (S. aureus), 26.3 ± 1 h (C. sporogenes), 223 ± 4.6 h (P. acnes), 64.4 ± 10 (C. albicans). A. brasiliensis was detected in i-FA Plus bottles with a TTD of 94.9 ± 3.7 h. The application of BacT/Alert FA Plus and FN Plus resin bottles in combination with a penicillin degrading enzyme is able to detect small scale microbial contamination with different microorganisms in antibiotic containing corneal culture medium. For detection of Aspergillus brasiliensis in the medium the (i-) FA Plus bottles should be used.

Performance of two resin-containing blood culture media in detection of bloodstream infections and in direct matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) broth assays for isolate identification: clinical comparison of the BacT/Alert Plus and Bactec Plus systems

We compared the clinical performances of the BacT/Alert Plus (bioMérieux) and Bactec Plus (Becton Dickinson) aerobic and anaerobic blood culture (BC) media with adsorbent polymeric beads. Patients ≥ 16 years old with suspected bloodstream infections (BSIs) were enrolled in intensive care units and infectious disease wards. A single 40-ml blood sample was collected from each and used to inoculate (10 ml/bottle) one set of BacT/Alert Plus cultures and one set of Bactec Plus cultures, each set consisting of one aerobic and one anaerobic bottle. Cultures were incubated ≤ 5 days in the BacT/Alert 3D and Bactec FX instruments, respectively. A total of 128 unique BSI episodes were identified based on the recovery of clinically significant growth in 212 aerobic cultures (106 BacT/Alert and 106 Bactec) and 151 anaerobic cultures (82 BacT/Alert and 69 Bactec). The BacT/Alert aerobic medium had higher recovery rates for Gram-positive cocci (P = 0.024), whereas the Bactec aerobic medium was superior for recovery of Gram-negative bacilli (P = 0.006). BacT/Alert anaerobic medium recovery rates exceeded those of the Bactec anaerobic medium for total organisms (P = 0.003), Gram-positive cocci (P = 0.013), and Escherichia coli (P = 0.030). In terms of capacity for diagnosing the 128 septic episodes, the BacT/Alert and Bactec sets were comparable, although the former sets diagnosed more BSIs caused by Gram-positive cocci (P = 0.008). They also allowed earlier identification of coagulase-negative staphylococcal growth (mean, 2.8 h; P = 0.003) and growth in samples from patients not on antimicrobial therapy that yielded positive results (mean, 1.3 h; P < 0.001). Similarly high percentages of microorganisms in BacT/Alert and Bactec cultures (93.8% and 93.3%, respectively) were identified by direct matrix-assisted laser desorption ionization-time of flight mass spectrometry assay of BC broths. The BacT/Alert Plus media line appears to be a reliable, timesaving tool for routine detection of BSIs in the population we studied, although further studies are needed to evaluate their performance in other settings.