FA Plus Research Articles

Comparison and evaluation of neutralization of clinically frequently used antimicrobial agents using three different culture media in simulated blood cultures.

We present a study on performance comparison of three different commercial culture media for neutralization of antibiotic effects in simulated blood cultures. BACT/ALERT (FA Plus and FN Plus) culture media with novel resin showed absolute advantages over DL and REDOX culture media at %PSL concentration of antimicrobials.

Comparison of new and old BacT/ALERT aerobic bottles for detection of Candida species.

A new version of aerobic blood culture media has been developed for the BacT/ALERT (bioMérieux) blood culture system. We evaluated the time to detection and yeast cell counts in positive blood cultures for each Candida spp. according to changes in media. Isolates from defibrinated horse blood were inoculated into three types of bottles: the old version of aerobic bottle, new version of aerobic bottle, and anaerobic bottle. All bottles were incubated in the BacT/ALERT Virtuo blood culture system. The time to detection was monitored for each bottle, and yeast cell counts were performed immediately after testing positive, determined via the plate count method. Clinical retrospective data of the candidemia samples before and after aerobic bottle change also were analyzed. The median time to detection was 52.47 hours in the old aerobic bottles versus 19.92 hours in the new aerobic bottles (P < 0.001) for Candida glabrata, and standard and clinical strains showed similar results. C. albicans (27.6 to 24.95 hours) and C. guilliermondii (28.92 to 26.9 hours) had shorter time to detection. However, C. auris (25.43 to 28.25 hours) had a longer time to detection in the new aerobic bottle. The retrospective clinical analysis showed a significant decrease in time to detection (45.0 to 19.4 hours) for C. glabrata, which is consistent with our simulated study result for C. glabrata. As a result of analysis including all blood specimens, C. tropicalis showed a significant delay in time to detection in new aerobic bottles. In an analysis limited to peripheral blood specimens, the time to detection of C. parapsilosis was longer in new aerobic bottles than in old aerobic bottles. Most Candida species did not show remarkable TTD differences, but TTD of C. glabrata was markedly reduced in the New FA Plus bottle. The reduction of time to detection enables faster detection and therapeutic approach for C. glabrata infections.

Efficient Recovery of Candida auris and Five Other Medically Important Candida Species from Blood Cultures Containing Clinically Relevant Concentrations of Antifungal Agents.

Candida auris and other Candida species (C. albicans, C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei) are important causes of bloodstream infection. Early or prolonged treatment with antifungal agents is often required. The inhibitory effect of antifungal agents in the patients' bloodstream may compromise the sensitivity of blood culture (BC) to diagnose and/or monitor patients with candidemia. Using a clinical BC simulation model, we compared antimicrobial drug-neutralizing BC media in BacT/Alert FA PLUS (FAP) or Bactec Plus Aerobic/F (PAF) bottles with non-neutralizing BC media in Bactec Mycosis IC/F (MICF) bottles to allow Candida growth in the presence of 100%, 50%, or 25% peak serum level (PSL) antifungal concentrations. In total, 117 organism/antifungal combinations were studied, and Candida growth was detected after incubating bottles into BacT/Alert VIRTUO or Bactec FX BC systems. Compared to control (without antifungal) bottles, both FAP and PAF bottles with 100% PSL antifungal concentrations allowed 100% recovery for C. auris, C. glabrata, and C. parapsilosis, whereas recovery was below 100% for C. albicans, C. krusei, and C. tropicalis. MICF bottles were less efficient at 100%, 50%, or 25% PSL antifungal concentrations, for all Candida species, except for C. auris. While azoles and amphotericin B did not hinder Candida growth in FAP or PAF bottles, echinocandins allowed C. auris, C. glabrata, and C. parapsilosis to grow in FAP, PAF, or MICF bottles. Overall, the maximum time to detection was 4.6 days. Taken together, our findings emphasize the reliability of BCs in patients undergoing antifungal treatment for candidemia. IMPORTANCE While echinocandins remain the preferred antifungal therapy for candidemia, bloodstream infections caused by C. auris, C. glabrata, or, at a lesser extent, C. parapsilosis may be difficult to treat with these antifungal agents. This is in view of the high propensity of the above-mentioned species to develop antifungal resistance or tolerance during treatment. Azoles and amphotericin B are possible alternatives. Thus, optimizing the recovery of Candida from BCs is important to exclude the likelihood of negative BCs for Candida species, owing to the inhibitory effect of antifungal agents present in the blood sample with which BCs are inoculated. Consistently, our results about the recovery of medically important Candida species (including C. auris) from simulated BCs in BacT/Alert FAP, Bactec PAF, or Bactec MICF bottles containing clinically relevant antifungal concentrations add support to this research topic, as well as to the use of BCs for monitoring the clinical and therapeutic course of candidemia.

Rapid syndromic approach to diagnosis of bacteremia – results of the first experience

Objective. To describe results of the first experience of using a syndromic approach to the diagnosis of bacteremia using multiplex panels for real-time polymerase chain reaction (real-time PCR). Materials and Methods. The prospective study included 10 consecutive positive blood cultures obtained from 10 patients in the intensive care unit after cardiac surgery. Hemocultures were carried out in BacT/ ALERT FA Plus vials using a BacT/ALERT 3D 120 incubator (bioMérieux, France). After short subcultivation on blood agar (4-6 hours), monocultures were identified using a MALDI-ToF mass spectrometer Vitek MS (bioMérieux, France) with sensitivity to antimicrobial drugs determined on a Vitek-2 compact analyzer (bioMérieux, France). The production of carbapenemases was detected phenotypically using a modified carbapenem inactivation method (mCIM test); the molecular type of enzymes was determined using immunochromatographic tests (NG-Test CARBA 5, NG Biotech, France). In parallel with the described process of identifying microorganisms and determining their sensitivity to antibiotics, positive blood cultures were analyzed using a FilmArray 2.0 analyzer and multiplex real-time PCR panels BioFire FilmArray BCID2 (bioMérieux, France). Results. Using MALDI-ToF mass spectrometry, the following microorganisms were identified in the studied blood cultures: K. pneumoniae (n = 5), E. faecalis (n = 2), A. baumannii (n = 1), Raoultella ornithinolytica (n = 1) and S. aureus (n = 1). 4⁄5 (80%) of K. pneumoniae isolates were resistant to carbapenems; another 1 isolate produced an ESBL and remained sensitive to carbapenems. All carbapenem-resistant K. pneumoniae gave a positive result of the mCIM test, while the immunochromatographic method detected the production of carbapenemases of the molecular types NDM (n = 1), KPC (n = 1), as well as combinations of KPC + OXA-48 (n = 1) and NDM + OXA-48 (n = 1). All E. faecalis were sensitive to ampicillin, isolates of A. baumannii and R. ornithinolytica remained sensitive to carbapenems, S. aureus was sensitive to cefoxitin. Using the real-time PCR, 9⁄10 (90%) pathogens were identified to species level in 10 positive blood cultures. In the remaining 1 case (R. ornithinolytica, not included in the list of detected species), the microorganism was assigned to the order Enterobacterales. The data obtained by the traditional method completely coincided with the results of real-time PCR analysis, while the time to obtain results was statistically significantly shorter compared to traditional microbiological method (22 hours versus 49 hours, p &lt; 0.001). In 7⁄10 (70%) cases, based on the results of real-time PCR analysis, a decision was made to change the tactics of antibiotic therapy. Conclusions. Real-time PCR analysis using BCID2 panels is an effective and reliable tool for the etiological diagnosis of bacteremia.

P034 Non-conventional alternatives to prevent Candida auris infections

Poster session 1, September 21, 2022, 12:30 PM - 1:30 PMObjectives Candida auris represents a particular organism associated with multiple nosocomial infections and high mortality rates. Appropriate infection control measures play a major role in controlling the spread and multiplication of this pathogen. Unfortunately, there are very few data available on the effectiveness of disinfectants against C. auris. Chlorine-based products appear to be the most effective for inanimate surface disinfection, while iodine-based products are more suitable for skin antisepsis. C. auris has been demonstrated to survive on dry and moist surfaces for up to 14 days, so environmental cleaning to eliminate a source of nosocomial infections is a challenge. Thus, searching for new effective fungicidal agents is still a hot topic nowadays. Non-thermal plasma-activated water (PAW) has recently emerged as a powerful antimicrobial agent, but no data about its effectiveness on C. auris are available. The aim of our study was to assess the possibility of using PAW as a fungicidal agent against C. auris planktonic cells.MethodsPAW was prepared using distilled water and a GlidArc reactor as previously described1. The final parameters of PAW were as follows: conductivity 446 ± 25 μS/cm, pH 2.78 ± 0.12, redox potential (ORP) + 1.06 V, NO2 192 ± 10 mg/L, NO3 1550 ± 95 mg/L, H2O2 2.6 ± 0.12 mg/L, and O3 1.08 ± 0.07 mg/L.A type strain of C. auris (CBS 10913) was used in this study. Suspensions of yeast cells (107 CFU/ml) were prepared from overnight cultures and subsequently treated with PAW in a ratio of 1:10 for different periods of time (1, 3, 5, 7, 10, 15, and 20 minutes). Precise volumes of the mixtures were further inoculated on Sabouraud Dextrose Agar plates and Bact/Alert FA Plus bottles (bioMerieux, France) in order to evaluate the reduction of yeast burden after each contact period. In addition, some instrumental analysis (IA) methods were used in order to assess the impact of PAW treatment on yeast cell structure: Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectrometry (FT-IR), and Dynamic Light Scattering (DLS). All tests were performed in triplicates.ResultsA reduction higher than 5 log10 of viable yeast was achieved in 3 minutes. The sterilization level (i.e., ˃6 log10 reduction) was achieved after 5 minutes for the tested strain. IA clearly objectified the morphological changes in the treated yeasts compared with the untreated ones (Figs. 1 and 2).ConclusionOur research has successfully demonstrated the fungicidal effect of PAW against C. auris, opening a new field of research in the area of disinfectants.1. Valentin Nastasa, Aurelian-Sorin Pasca, Razvan-Nicolae Malancus, Andra-Cristina Bostanaru, Luminita-Iuliana Ailincai, Elena-Laura Ursu, Ana-Lavinia Vasiliu, Bogdan Minea, Eugen Hnatiuc, Mihai Mares, [2021] - Toxicity Assessment of Long-Term Exposure to Non-Thermal Plasma Activated Water in Mice, Int. J. Mol. Sci., 22(21), 11 534; https://doi.org/10.3390/ijms222111534.

Blood culture surveillance in a secondary care hospital in Benin: epidemiology of bloodstream infection pathogens and antimicrobial resistance

BackgroundAlthough global surveillance of antimicrobial resistance (AMR) is considered key in the containment of AMR, data from low- and middle-income countries, especially from sub-Saharan Africa, are scarce. This study describes epidemiology of bloodstream infections and antimicrobial resistance rates in a secondary care hospital in Benin.MethodsBlood cultures were sampled, according to predefined indications, in BacT/ALERT FA Plus and PF Plus (bioMérieux, Marcy-l’Etoile, France) blood culture bottles (BCB) in a district hospital (Boko hospital) and to a lesser extent in the University hospital of Parakou. These BCB were incubated for 7 days in a standard incubator and twice daily inspected for visual signs of growth. Isolates retrieved from the BCB were processed locally and later shipped to Belgium for reference identification [matrix-assisted laser desorption/ionization time-of-flight spectrometry (MALDI-TOF)] and antibiotic susceptibility testing (disk diffusion and E-tests).ResultsFrom October 2017 to February 2020, 3353 BCB were sampled, corresponding to 3140 blood cultures (212 cultures consisting of > 1 BCB) and 3082 suspected bloodstream infection (BSI) episodes. Most of these cultures (n = 2471; 78.7%) were sampled in children < 15 years of age. Pathogens were recovered from 383 (12.4%) cultures, corresponding to 381 confirmed BSI. 340 of these pathogens were available and confirmed by reference identification. The most common pathogens were Klebsiella pneumoniae (n = 53; 15.6%), Salmonella Typhi (n = 52; 15.3%) and Staphylococcus aureus (n = 46; 13.5%). AMR rates were high among Enterobacterales, with resistance to third-generation cephalosporins in 77.6% of K. pneumoniae isolates (n = 58), 12.8% of Escherichia coli isolates (n = 49) and 70.5% of Enterobacter cloacae isolates (n = 44). Carbapenemase production was detected in 2 Escherichia coli and 2 Enterobacter cloacae isolates, all of which were of the New Delhi metallo-beta lactamase type. Methicillin resistance was present in 22.4% of S. aureus isolates (n = 49).ConclusionBlood cultures were successfully implemented in a district hospital in Benin, especially among the pediatric patient population. Unexpectedly high rates of AMR among Gram-negative bacteria against commonly used antibiotics were found, demonstrating the clinical and scientific importance of clinical bacteriology laboratories at this level of care.

Implementation of Automated Blood Culture With Quality Assurance in a Resource-Limited Setting.

Background: Blood cultures (BC) have a high clinical relevance and are a priority specimen for surveillance of antimicrobial resistance. Manual BC are still most frequently used in resource-limited settings. Data on automated BC performance in Africa are scarce. We implemented automated BC at a surveillance site of the African Network for improved Diagnostics, Epidemiology and Management of Common Infectious Agents (ANDEMIA).Methods: Between June 2017 and January 2018, pairs of automated BC (BacT/ALERT®FA Plus) and manual BC (brain-heart infusion broth) were compared at a University hospital in Bouaké, Côte d'Ivoire. BC were inoculated each with a target blood volume of 10 ml from the same venipuncture. Automated BC were incubated for up to 5 days, manual BC for up to 10 days. Terminal subcultures were performed for manual BC only. The two systems were compared regarding yield, contamination, and turnaround time. For quality assurance, isolates were retested in a German routine microbiological laboratory.Results: BC sampling was increased from on average 24 BC to 63 BC per month. A total of 337 matched pairs of BC were included. Automated BC was positive in 36.5%, manual BC in 24.0% (p-value < 0.01), proportion of contamination was 47.9 and 43.8%, respectively (p-value = 1.0). Turnaround time of positive BC was shortened by 2.5 days with automated compared to manual BC (p < 0.01). Most common detected pathogens in both systems were Klebsiella spp. (26.0%) and Staphylococcus aureus (18.2%). Most contaminants were members of the skin flora. Retesting of 162 isolates was concordant in 79.6% on family level.Conclusions: Implementing automated BC in a resource-limited setting is possible and improves microbiological diagnostic performance. Automated BC increased yield and shortened turnaround times. Regular training and mentorship of clinicians has to be intensified to increase number and quality of BC. Pre-analytical training to improve diagnostic stewardship is essential when implementing a new microbiological method. Retesting highlighted that manual identification and antimicrobial susceptibility testing can be of good quality and sustainable. The implementation of automated tools should be decided individually according to economic considerations, number of samples, stable supply chain of consumables, and technical sustainability.

Evaluation of Optimal Blood Culture Incubation Time To Maximize Clinically Relevant Results from a Contemporary Blood Culture Instrument and Media System.

Timely diagnosis of microorganisms in blood cultures is necessary to optimize therapy. Although blood culture media and systems have evolved for decades, the standard interval for incubation prior to being discarded as negative has remained 5 days. Here, we evaluated the optimal incubation time for the BacT/Alert Virtuo blood culture detection system (bioMérieux) using FA Plus (aerobic) and FN Plus (anaerobic) resin culture bottles in routine clinical use. Following institutional review board (IRB) approval, a retrospective review evaluated the outcomes of 158,710 bottles collected between November 2018 and October 2019. The number of positive blood bottles was 13,592 (8.6%); 99% of positive aerobic and anaerobic bottles flagged positive by 91.5 and 108 h, respectively. The mean (median) times to positivity were 18.4 h (15.6 h) for Staphylococcus aureus, 12.3 h (9.5 h) for Escherichia coli, 22.2 h (15.9 h) for Pseudomonas aeruginosa, and 48.9 h (42.9 h) for Candida spp. Only 175 bottles (0.1% of all bottles) flagged positive after 4 days of incubation; 89 (51%) of these bottles grew Cutibacterium (Propionibacterium) species. Chart review of blood cultures positive after 4 days (96 h) rarely had a clinical impact and sometimes had a negative impact on patient care. Finally, a seeded study of the HACEK group (i.e., Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella), historically associated with delayed blood culture positivity, demonstrated no benefit to extended incubation beyond 4 days. Collectively, these findings demonstrated that a 4-day incubation time was sufficient for the Virtuo system and media. Implementation of the 4-day incubation time could enhance clinically relevant results by reducing recovery of contaminants and finalizing blood cultures 1 day earlier.

Inactivation of Clinically Frequently Used Antimicrobial Agents By BacT/ALERT FAN Plus and BACTEC Aerobic and Anaerobic Culture Media in Simulated Blood Cultures: First Comparative Evaluation in China Mainland.

PurposeTo evaluate the antimicrobial inactivation capabilities of BacT/ALERT (FA Plus and FN Plus) and BACTEC (Plus Aerobic/F and Lytic/10 Anaerobic/F) media.Patients and MethodsThe inactivation capabilities of the commercial blood culture media were compared using 21 microorganism-antimicrobial combinations in simulated adult blood cultures.ResultsBacT/ALERT culture media demonstrated higher detection rates than the BACTEC culture media. The recovery rates of the aerobic bottles were 74/115 (64.3%) for FA Plus bottles and 64/115 (55.7%) for BACTEC Aerobic Plus bottles. The BacT/ALERT FAN Plus culture media exhibited a shorter time to detection (TTD). The TTD of FA Plus media was 14.7 h, 4.85 h shorter than the BACTEC Aerobic media (19.55 h), while the TTDs of FN Plus media and BACTEC Anaerobic media were 16.8 h and 18.4 h, respectively.ConclusionBacT/ALERT (FA Plus and FN Plus) media showed relative, but not absolute, advantages, as it had higher detection rates and shorter TTD and thus can be selectively applied to patients with prior use of antimicrobial agents before blood culture samples are taken.

Nonautomated Blood Cultures in a Low-Resource Setting: Optimizing the Timing of Blind Subculture.

.Laboratory procedures for blood cultures in a hospital in Phnom Penh were adapted to optimize detection of Burkholderia pseudomallei, an important pathogen in this setting. The effects of these changes are analyzed in this study. Blood cultures consisted of two BacT/ALERT bottles (bioMérieux, Marcy-l’Etoile, France). Growth was detected visually by daily inspection of the bottles. In 2016, the aerobic–anaerobic pair (FA/FN FAN) was substituted by an aerobic pair of BacT/ALERT FA Plus bottles. Blind subculture (BS) (subculture in the absence of visual growth) was advanced from day 3 to day 2 of incubation in July 2016. In July 2018, it was further advanced to day 1 of incubation. From July 2016 to October 2019, 9,760 blood cultures were sampled. The proportion of cultures showing pathogen growth decreased from 9.6% to 6.8% after the implementation of the laboratory changes (P < 0.001). Advancing the BS from day 3 to day 2 led to an increased proportion of pathogens detected by day 3 (92.8% versus 82.3%; P < 0.001); for B. pseudomallei, this increase was even more remarkable (92.0% versus 18.2%). Blind subculture on day 1 similarly increased the proportion of pathogens detected by day 2 (82.9% versus 69.0% overall, 66.7% versus 10.0% for B. pseudomallei; both P < 0.001). However, after implementation of day 1 subculture, a decrease in recovery of B. pseudomallei was observed (12.4% of all pathogens versus 4.3%; P < 0.001). In conclusion, earlier subculture significantly shortens time to detection and time to actionable results. Some organisms may be missed by performing an early subculture, especially those that grow more slowly.

Effect of delayed entry on performance of the BACT/ALERT FAN PLUS bottles in the BACT/ALERT VIRTUO blood culture system

Delayed entry of patient blood culture samples into a microbial detection system is unavoidable at times, due to off-shift staffing or transporting samples to centralized laboratories. Pre-incubation time and temperature of blood culture bottles are the most critical factors impacting recovery and detection of microorganisms. A total of 1377 BACT/ALERT® (BTA) Fastidious Antimicrobial Neutralization (FAN® PLUS) bottles (FA PLUS, FN PLUS, and PF PLUS) were tested after delayed entry times of 24 and 36 h at 20–25 °C (room temperature, RT) prior to loading into the BACT/ALERT® VIRTUO® microbial detection system (VIRTUO). Clinically relevant organisms were inoculated into bottles with 5–84 colony forming units (CFU) per bottle, and human blood (0 to 10 mL), and then loaded into the VIRTUO. When bottles were loaded without delay, a mean time to detection (TTD) of 9.6 h was observed. For delayed bottles, the TTD reported by the VIRTUO was added to the 24-h and 36-h delay times and resulted in average time to results of 32.5 h and 42.5 h, respectively. The FAN PLUS bottles in conjunction with the VIRTUO produced acceptable results when delays up to 24 h at 20–25 °C occur in loading.

Eye Diseases Monitoring Using Statistical Analysis of Disc Topography and RNFL Circular Tomogram Parameters

In this paper, Statistics method for data taken from ophthalmology institute of Cairo, Egypt used to pinpoint the absolute measurement precision of high resolution technique of Topcon three dimensional optical coherence topography FA plus (Topcon 3D OCT FA plus) parameters by expressing them as limit of agreement percentage ( LA95%) then, suggest a method for mathematically evaluating the ability of parameter to monitor ailment progression expressed as Discriminate Capacity Index (DCI) then, select parameters suitable for both conversion to glaucoma and modify to outright glaucoma . The used Parameters were area of disc, cup, rim and cup to disc ratio, linear and veridical cup to disc ratio, volume of cup, rim volume, horizontal and vertical diameter, total thickness of retinal nerve fiber layer (RNFL), average superior thickness of RNFL and average inferior thickness of RNFL parameters have been arranged with a DCI ≥ 0.4 for glaucoma detection and with a DCI≥ 2.3 for continue of glaucoma. The most adequate parameters for both detection and follow-up of glaucoma are Inferior thickness of RNFL (DCI=4.1976), total thickness of RNFL (DCI=16.56) and vertical cup- to- disc ratio (CDR) (DCI=22.1875).

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 2.8h shorter in FA PLUS bottles (12.4h) compared to BD Aerobic bottles (15.2h) (p < 0.001). And the TTD from anaerobic culture was 1.6h shorter in FN PLUS bottles (18.1h) compared to BD Anaerobic bottles (19.7h) (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.

Efficient Inactivation of Clinically Relevant Antimicrobial Drug Concentrations by BacT/Alert or Bactec Resin-Containing Media in Simulated Adult Blood Cultures.

We assessed the antimicrobial-inactivation capability of BacT/Alert (FA Plus and FN Plus) or Bactec (Plus Aerobic/F and Plus Anaerobic/F) media for 40 antibiotic-bacterium combinations in simulated adult blood cultures. Aside from high recovery rates (93.2% and 88.4%, respectively), we showed that at the lowest but clinically relevant antibiotic concentrations, both BacT/Alert and Bactec media recovered all the organisms tested with drugs except for Escherichia coli, which was tested in the presence of meropenem. Delayed recoveries were mainly associated with vancomycin.

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

ObjectivesContinuous 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. MethodsPeritoneal, 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. ResultsA 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. ConclusionsThe 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.

Effects of Clinically Meaningful Concentrations of Antipseudomonal β-Lactams on Time to Detection and Organism Growth in Blood Culture Bottles.

The effectiveness of antimicrobial binding resins present in blood culture (BC) bottles in removing meropenem, ceftolozane-tazobactam, and ceftazidime-avibactam is unknown. We assessed the time to detection (TTD) and growth of 2 Pseudomonas aeruginosa isolates in the presence of clinically meaningful concentrations of these antibiotics. Bactec Plus Aerobic/F and BacT/Alert FA Plus BC bottles were inoculated with one of two isolates (1 meropenem susceptible and 1 resistant), followed by fresh whole blood containing the peak, midpoint, or trough plasma concentrations for meropenem, ceftolozane-tazobactam, and ceftazidime-avibactam. Matching bottles were loaded into their respective detection instruments and a standard incubator at 37°C, with TTD and CFU being monitored for up to 72 h. Bacterial growth was observed for 11/48 (22.9%), 22/48 (45.8%), and 47/48 (97.9%) of all BC bottles inoculated with the peak, midpoint, and trough concentrations, respectively (P ≤ 0.001). When P. aeruginosa was isolated, the TTD was typically <26 h, and no differences between Bactec and BacT/Alert bottles were observed. In both systems, meropenem was removed to a greater degree than were ceftolozane and ceftazidime; however, concentrations for all antibiotics remained above the MIC for the susceptible organisms at 12 h. BC bottles containing antibiotic binding resins may not sufficiently inactivate achievable concentrations of meropenem, ceftolozane-tazobactam, and ceftazidime-avibactam. The consistent identification of both P. aeruginosa isolates was observed only in the presence of antibiotic trough concentrations. To minimize false-negative BC results for patients already receiving these antibiotics, cultures should be collected just prior to the next dose, when antibiotic concentrations are lowest.

A controlled comparison of the BacT/ALERT\xae 3D and VIRTUO\u2122 microbial detection systems

The performance of the next-generation BacT/ALERT® VIRTUO™ Microbial Detection System (VIRTUO™, bioMérieux Inc., Hazelwood, MO) was compared to the BacT/ALERT® 3D Microbial Detection System (3D, bioMérieux Inc., Durham, NC) using BacT/ALERT® FA Plus (FA Plus), BacT/ALERT® PF Plus (PF Plus), BacT/ALERT® FN Plus (FN Plus), BacT/ALERT® Standard Aerobic (SA), and BacT/ALERT® Standard Anaerobic (SN) blood culture bottles (bioMérieux Inc., Durham, NC). A seeded limit of detection (LoD) study was performed for each bottle type in both systems. The LoD studies demonstrated that both systems were capable of detecting organisms at nearly identical levels [<10 colony-forming units (CFU) per bottle], with no significant difference. Following LoD determination, a seeded study was performed to compare the time to detection (TTD) between the systems using a panel of clinically relevant microorganisms inoculated at or near the LoD with 0, 4, or 10 mL of healthy human blood. VIRTUO™ exhibited a faster TTD by an average of 3.5 h, as well as demonstrated a significantly improved detection rate of 99.9% compared to 98.8% with 3D (p-value <0.05).

The Effect of Clinical Concentrations of Meropenem (MEM), Ceftolozane/tazobactam (C/T), and Ceftazidime/avaibactam (CZA) on Time to Detection (TTD) and Growth of Pseudomonas aeruginosa (PSA) in bioMerieux BacT/ALERT®FA Plus Blood Culture (BC) Bottles

BackgroundAntimicrobial binding agents (ABA) are added to BC bottle media to reduce TTD and prevent false negatives that may result when BCs are obtained in patients receiving antibiotics. Sparse data are available on the effectiveness of ABA containing BacT/ALERT®FA Plus BC bottles against MEM, C/T and CZA, which are often administered as high dose and/or prolonged infusion regimens for suspected PSA infections.MethodsBC bottles were inoculated with 10ml of fresh whole blood collected from healthy volunteers. The blood was spiked to achieve mean peak, midpoint, and trough concentrations of MEM (40, 20 and 5 µg/mL), C/T (150, 50, and 8 µg/mL), and CZA (90, 25, and 10 µg/mL), respectively. A control bottle containing no antibiotic was included. BC bottles were then inoculated with 7–30 colony forming units (CFU)/bottle of either a MEM susceptible (MEM-S) (MIC = 0.5 µg/mL, C/T = 0.5 µg/mL, CZA = 2 µg/mL) or MEM resistant (MEM-R) PSA (MIC = 8 µg/mL, C/T = 4 µg/mL, CZA = 8 µg/mL) isolate. Matching bottles were entered into a BacT/ALERT®-3D detection instrument and a standard incubator at 37° C for up to 72h. Each series was conducted in duplicate. TTD was measured in the detection instrument, and CFUs were counted at 0, 4, 12, 24, 36, 48, 60, and 72h in incubated bottles.ResultsControl PSA grew to 7.4 × 108/mL with a TTD of 15.5–19.5 hours. Both PSA grew in the presence of MEM trough concentrations with TTD of 21.3 ± 3.3 hours. However, midpoint and peak concentrations inhibited growth of the MEM-S PSA. The MEM-R PSA grew in the presence of all MEM concentrations, with a TTD of 18.6 ± 0.5 hours. Both PSA grew in the presence of C/T trough concentrations with TTD of 23.0 ± 2.6 hours, but were inhibited by midpoint and peak C/T concentrations. For CZA, both PSA grew in the presence of trough concentrations with TTD of 20.1 ± 1.9 hours. Peak CZA concentrations inhibited growth of both PSA, while midpoint concentrations inhibited growth of the MEM-S isolate.ConclusionThese are the first data to show that BacT/ALERT BC bottles containing ABA may not sufficiently inactivate achievable concentrations of MEM, C/T or CZA, which could result in false negatives. In patients already receiving one of these antibiotics, BCs should be collected just prior to the next dose to increase the probability of PSA detection.Disclosures All authors: No reported disclosures.

Apport de l’OCT-SD maculaire dans le diagnostic et le pronostic de l’hypoplasie fovéolaire chez les patients ayant un nystagmus

To investigate whether spectral domain optical coherence tomography (SD-OCT) is helpful for the diagnosis and prognosis of foveal hypoplasia in patients with overt nystagmus. A retrospective cross-sectional study was conducted in 48 patients with overt nystagmus. All patients underwent a complete ophthalmic examination including best corrected visual acuity, biomicroscopic and fundus examinations. Spectral domain optical coherence tomography was performed using 3D OCT-2000 FA PLUS Topcon, Tokyo, Japan, for the diagnosis and grading of foveal hypoplasia, using the Thomas classification, and its possible correlation with visual acuity. Foveal hypoplasia was diagnosed in 6 patients (12.5%). The mean age of the patients was 13.2 years (10-18 years). Mean visual acuity was 1.53/10 (0.87 LogMAR). Foveal hypoplasia was associated with aniridia in 2 patients, albinism in 3 patients and keratoconus in 1 case. On SD-OCT, foveal hypoplasia was grade 4 in 4 patients and grade 3 in 2 patients. Mean visual acuity was 2.55/10 in patients with grade 3 foveal hypoplasia and 1.22/10 in patients with grade 4 foveal hypoplasia, and the difference in visual acuity between the two groups was statistically significant (P<0.001). SD-OCT plays a double role in the diagnosis and prognosis of foveal hypoplasia in patients with nystagmus.

Identification of Microorganisms by FilmArray and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Prior to Positivity in the Blood Culture System

In this study, we investigated the performance of the FilmArray and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in identifying microorganisms from blood culture (BC) bottles prior to positivity. First, we used simulated BacT/Alert FA Plus BC bottles with five each for Escherichia coli and Staphylococcus aureus isolates. The FilmArray identified all 10 isolates before BC positivity with 9/10 at 5 h and 1 at 7.5 h after incubation in the BC system. MALDI-TOF MS failed to identify the isolates prior to positivity. When the bottles were incubated for 2.5 h at room temperature (RT) before we put them into the BC system, the FilmArray identified 6/10 at 2.5 h and the remaining 4 at 5 h. Finally, we tested simulated BC bottles after incubation at RT. Interestingly, 9/10 isolates were identified with the FilmArray after 8 h of incubation at RT. Second, we studied clinical BC bottles in quadruplicate. When three-fourths of the parallel bottles signaled positive, the FilmArray was run on the fourth nonsignaled bottle and was found to be positive in 14/15 such cases. Third, we analyzed the performance of the FilmArray in the identification of microorganisms from clinical BC bottles before incubation in the system. Two milliliters of broth from 400 BC bottles was collected after arrival at the laboratory and stored at -70°C. Sixteen bottles later signaled positive in the system. When the frozen broth from these bottles was analyzed, the FilmArray identified all the microorganisms in 8/16 bottles prior to incubation in the BC system. This study shows that the FilmArray can identify microorganisms from BC bottles prior to positivity and in some cases even prior to incubation in the BC system.