Detection of fifteen species of Candida in an automated blood culture system

Pitt candidaemia score as an assessment tool for mortality in patients with candidaemia caused by Candida tropicalis and other Candida species: a multicentre study conducted in Japan

Background

A bedside scoring system to assess the severity of disease is lacking for candidaemia. The Pitt candidaemia score (PCS) was evaluated for its association with mortality.

Methods

The PCS consists of five components, namely dialysis, hypotension, mechanical ventilation, cardiac arrest and mental status. Patients were classified into four categories according to their PCS. The correlation between PCS category at blood culture collection and 30 day mortality was studied individually for five Candida species.

Results

Leading rates of mortality were observed in Candida tropicalis and Candida krusei. The interval from inoculation to positive culture was 19.4 ± 9.7 h for C. tropicalis and 21.3 ± 5.6 h for C. krusei; these intervals were significantly shorter than those for other Candida species. In a Kaplan-Meier survival curve, a significant risk stratification by PCS category was demonstrated in all Candida species. A high PCS was an independent risk factor for mortality, and source control decreased the risk for C. tropicalis and Candida glabrata infections. Regarding antifungal therapy, the median PCS was 8 for liposomal amphotericin B, 2 for echinocandins and 0 for azoles, and this trend was consistent among four Candida species.

Conclusions

The mortality rate was well stratified by the PCS, and the PCS affected the selection of antifungals. A future prospective study is required for the PCS in guiding therapy for candidaemia.

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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Noninvasive Testing and Surrogate Markers in Invasive Fungal Diseases

Invasive fungal infections continue to increase as at-risk populations expand. The high associated morbidity and mortality with fungal diseases mandate the continued investigation of novel antifungal agents and diagnostic strategies that include surrogate biomarkers. Biologic markers of disease are useful prognostic indicators during clinical care, and their use in place of traditional survival end points may allow for more rapid conduct of clinical trials requiring fewer participants, decreased trial expense, and limited need for long-term follow-up. A number of fungal biomarkers have been developed and extensively evaluated in prospective clinical trials and small series. We examine the evidence for these surrogate biomarkers in this review and provide recommendations for clinicians and regulatory authorities.

Blood culture quality assurance: what Australasian laboratories are measuring and opportunities for improvement

Blood cultures are among the most important specimen types received and processed by the microbiology laboratory. Several publications list which variables should be measured to ensure quality. We undertook a qualitative structured questionnaire of Australian and New Zealand clinical microbiology laboratories to document current blood culture practices and to determine whether expected quality standards are being met. Questions included a wide range of pre-analytical, analytical, and post-analytical aspects of blood cultures from adults. The responses from 71 laboratories were analysed. Compliance was high for use of a biological safety cabinet (90%), incubating for 5 days (86%), and commenting on likely contaminants (85%). While Gram stains were reported within 2 hours during normal hours (93%), reporting was slower after hours (59%), p<0.001. The volume of blood collected for a clinical episode was poorly monitored with only 11% (n=8) of laboratories regularly auditing the number of blood culture sets and 3% (n=2) monitoring adequacy of fill. Most laboratories received blood cultures from off-site with just 34% (n=21) meeting guidance for loading bottles onto the analyser within 4 hours. More laboratories met standards for loading bottles onto the analyser during working hours than after hours: 87% vs 56%, p<0.001. Most laboratories did not monitor the contamination rate, 56% (n=40), and only 27% (n=19) knew their rate was below the guidance threshold of less than -3%. Considerable opportunities exist to improve quality assurance of blood culture practice in Australia and New Zealand, especially for the most critical aspect affecting culture sensitivity, the volume of blood collected.

Application of High-Resolution Melting PCR to Detect the Genomic Fungal ITS 2 Region

BACKGROUND

Invasive fungal infections (IFIs) are a main cause of morbidity and mortality. High-resolution melting polymerase chain reaction (HRM PCR) is promising for the identification of fungal species via the detection of internal transcribed spacer 2 (ITS2).

OBJECTIVES

To assess the sensitivity and specificity of HRM PCR in diagnosing IFIs, compared with blood culture.

METHODS

Our study included 100 patients who were suspected of having IFIs; we analyzed their specimens via blood culture and HRM PCR.

RESULTS

Blood culture results were positive in 57 cases and negative in 43 cases. HRM PCR results were positive in 14 cases and negative in 86 cases. The 14 cases with positive results included 4 with Candida tropicalis, 4 with Candida glabrata, and 6 with Candida krusei. HRM PCR sensitivity was 24.6%, specificity was 100%, positive predictive value (PPV) was 100%, and negative predictive value (NPV) was 50%.

CONCLUSIONS

HRM PCR is specific but not sensitive. Blood culture is more sensitive and cannot be replaced by HRM PCR.

Comparison of the Performance of Three Blood Culture Systems in a Chinese Tertiary-Care Hospital

In this study, we evaluated the performance of three blood culture systems in a Chinese tertiary-care hospital. Samples of simulated bacteremia were prepared using 10 mL of fresh blood from healthy humans and bacterial suspensions of known cell density. Portions of the specimens were treated with an antibiotic or antifungal drug at specified concentrations to simulate antibacterial drug treatment. We analyzed three blood culture systems: BACTEC Plus, BacT/Alert, and VersaTREK. Both time-to-detection (TTD) of 10 types of bacteria and five types of yeasts in samples without antibiotic treatment and positive detection rate of samples treated with different concentrations of antibiotic or antifungal drugs were compared among the culture systems. We also retrospectively analyzed the use of the culture systems in our hospital from 2015 to 2018. In the simulated study, in the absence of antibiotics, the VersaTREK REDOX 1 displayed the shortest TTD for Pseudomonas aeruginosa, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, Candida albicans, and Candida glabrata (P < 0.001). Among the anaerobically cultured samples, BACTEC lytic/10 anaerobic/F displayed the shortest TTD for Escherichia coli, S. aureus, Enterococcus faecalis, S. pneumoniae, Bacteroides fragilis, and Bacteroides vulgatus (P < 0.001). Comparatively, BacT/Alert FA/FN showed no advantages. In antibiotic-treated samples, overall recovery rates for the BACTEC, BacT/Alert, and VersaTREK systems were, were 70.2, 43.7, and 27.4%, respectively. BACTEC facilitated higher recovery rate than the other two systems (P < 0.001). In antifungal treatment, the overall recovery rates for the BACTEC, BacT/Alert, and VersaTREK systems were 93.9, 98.3, and 69.4%, respectively. BACTEC Plus showed a recovery rate comparable to that of BacT/Alert (P = 0.835), and the recovery rate of both these systems was higher than that of VersaTREK (P < 0.001). The TTD values and positive rates determined in the retrospective study were consistent with those obtained in the simulated study. The combination of BACTEC PLUS Aerobic/F and BACTEC lytic/10 anaerobic/F culture systems displayed the best clinical performance. Furthermore, the BacT/Alert FAN culture system was found to be more resistant to antifungal drugs and levofloxacin, whereas the VersaTREK system is considered more suitable for primary blood cultures without antibiotic supplementation.

Rapid Isolation and Concentration of Pathogenic Fungi Using Inertial Focusing on a Chip-Based Platform

Systemic Candida infections remain a leading cause of nosocomial infections in the United States and worldwide. Many challenges remain in achieving rapid, direct diagnosis of fungal bloodstream infections due to limitations of conventional diagnostic methods that continue to demonstrate poor sensitivity, prolonged culture times that lead to delayed treatment, and detection variability between tests that compromises result reproducibility. Despite advancements in technology, mortality, and cost of care presented by blood stream infection with Candida spp. (candidemia) continues to rise and there is an urgent need for the development of novel methods to accurately detect Candida species present within the blood. This is especially true when patients are infected with drug resistant strains of Candida where accurate and immediate therapeutic treatment is of the importance. This study presents a method of separating fungal cells from lysed blood using inertial forces applied through microfluidics in order to abbreviate the time required to achieve a diagnosis by mitigating the need to grow blood cultures. We found that C. albicans can segregate into a focused stream distinct from white blood cells isolated within the Inertial Fungal Focuser (IFF) after red blood cell lysis. As a result of the focusing process, the collected cells are also concentrated 2.86 times. The same IFF device is applicable to non-albicans species: Candida parapsilosis, Candida glabrata, and Candida tropicalis, providing both isolation from lysed blood and a reduction in solution volume. Thus, the devised platform provides a means to isolate medically significant fungal cells from blood and concentrate the cells for further interrogation.

Use of T2MR in invasive candidiasis with and without candidemia

The mortality associated with invasive candidiasis remains unacceptably high. The T2 magnetic resonance (T2MR) assay is a novel US FDA-approved molecular diagnostic assay for the diagnosis of candidemia that can rapidly detect the five most commonly isolated Candida spp. In clinical trials, T2MR has exhibited good clinical sensitivity and specificity. Potential benefits from the adoption of T2MR technology in the diagnostic and therapeutic algorithms for invasive candidiasis can arise from timely diagnosis of disease, increased case detection, tailored therapy and decrease in empiric antifungal treatment. As everyday clinical experience with the assay is evolving, we discuss the utility of T2MR in invasive candidiasis with and without candidemia based on the currently available evidence regarding its performance.

T2 Magnetic Resonance Assay: Overview of Available Data and Clinical Implications

Invasive candidiasis is a common healthcare-associated infection with a high mortality rate that can exceed 60% in cases of septic shock. Blood culture performance is far from ideal, due to the long time to positivity and suppression by antifungal agents. The T2 Magnetic Resonance (T2MR) assay is an FDA-approved qualitative molecular diagnostic method that can detect and speciate the 5 most common Candida spp.; namely, Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, and Candida krusei, in approximately 5 h. In a multicenter clinical trial that included both a prospective and a contrived arm to represent the full range of clinically relevant concentrations of Candida spp., T2MR demonstrated a sensitivity and specificity of 91.1% and 98.1%, respectively. The utility of T2MR in candidemia depends on the prevalence of disease in each clinical setting. In intensive care units and other high-prevalence settings, the incorporation of T2MR in diagnostic algorithms is very appealing. T2MR is expected to allow timely initiation of antifungal therapy and help with anti-fungal stewardship. In low-prevalence settings, the positive predictive value of T2MR might not be enough to justify initiation of antifungal treatment in itself. The performance of T2MR has not been studied in cases of deep-seated candidiasis. Despite some promising evidence in published clinical trials, further studies are needed to determine the performance of T2MR in invasive candidiasis without candidemia. Overall, experience with T2MR in everyday clinical practice is evolving but, in the right setting, this technology is expected to provide “actionable information” for the management of patients evaluated for candidemia.

Recent developments in the management of invasive fungal infections in patients with oncohematological diseases

Patients with hematological cancer have a high risk of invasive fungal diseases (IFDs). These infections are mostly life threatening and an early diagnosis and initiation of appropriate antifungal therapy are essential for the clinical outcome. Most commonly, Aspergillus and Candida species are involved. However, other non-Aspergillus molds are increasingly be identified in cases of documented IFDs. Important risk factors are long lasting granulocytopenia with neutrophil counts below 500/μl for more than 10 days or graft-versus-host disease resulting from allogeneic stem-cell transplantation. For definite diagnosis of IFD, various diagnostic tools have to be applied, including conventional mycological culture and nonconventional microbiological tests such as antibody/antigen and molecular tests, as well as histopathology and radiology. In the last few years, various laboratory methods, like the Aspergillus GM immunoassay (Aspergillus GM EIA), 1,3-ß-D-glucan (BG) assay or polymerase chain reaction (PCR) techniques have been developed for better diagnosis. Since no single indirect test, including radiological methods, provides the definite diagnosis of an invasive fungal infection, the combination of different diagnostic procedures, which include microbiological cultures, histological, serological and molecular methods like PCR together with the pattern of clinical presentation, may currently be the best strategy for the prompt diagnosis, initiation and monitoring of IFDs. Early start of antifungal therapy is mandatory, but clinical diagnostics often do not provide clear evidence of IFD. Integrated care pathways have been proposed for management and therapy of IFDs with either the diagnostic driven strategy using the preemptive antifungal therapy as opposed to the clinical or empirical driven strategy using the 'traditional' empirical antifungal therapy. Antifungal agents preferentially used for systemic therapy of invasive fungal infections are amphotericin B preparations, fluconazole, voriconazole, posaconazole, caspofungin, anidulafungin, micafungin, and most recently isavuconazole. Clinical decision making must consider licensing status, local experience and availability, pharmacological and economic aspects.

Evaluation of the BD BACTEC FX blood volume monitoring system as a continuous quality improvement measure

The yield of blood cultures is proportional to the volume of blood cultured. We evaluated an automatic blood volume monitoring system, recently developed by Becton Dickinson within its BACTEC EpiCenter module, that calculates mean volumes of negative aerobic bottles and generates boxplots and histograms. First, we evaluated the filling degree of 339 aerobic glass blood cultures by calculating the weight-based volume for each bottle. A substantial amount of the bottles (48.3%) were inadequately filled. Evaluation of the accuracy of the monitoring system showed a mean bias of -1.4 mL (-15.4%). Additional evaluation, using the amended software on 287 aerobic blood culture bottles, resulted in an acceptable mean deviation of -0.3 mL (-3.3%). The new software version was also tested on 200 of the recently introduced plastic bottles, which will replace the glass bottles in the near future, showing a mean deviation of +2.8 mL (+26.7%). In conclusion, the mean calculated volumes can be used for the training of a single phlebotomist. However, filling problems appear to be masked when using them for phlebotomist groups or on wards. Here, visual interpretation of boxplots and histograms can serve as a useful tool to observe the spread of the filling degrees and to develop a continuous improvement program. Re-adjustment of the software has proven to be necessary for use with plastic bottles. Due to our findings, BD has developed further adjustments to the software for validated use with plastic bottles, which will be released soon.

Longer incubation times for yeast fungemia: importance for presumptive treatment

Isolation rates of Candida glabrata at ≤2 days were 8.9% and 34.8% at >2 days; for Cryptococcus neoformans, they were 0.9% and 8.6%, respectively (1741 fungemia analyzed). An incubation time >2 days supports candins as presumptive treatment for C. glabrata, keeping in mind the risk of Cryptococcus fungemia.

Comparison of the T2Dx instrument with T2Candida assay and automated blood culture in the detection of Candida species using seeded blood samples

As a delay in the diagnosis and treatment of candidemia is associated with increased mortality and healthcare costs, a more rapid method of detection is urgently needed. The T2Candida assay is a new rapid diagnostic test, which uses T2 magnetic resonance technology to identify Candida spp. directly from whole blood in approximately 3 hours. In this study, the performance of the BACTEC 9050 using Aerobic Plus/F blood culture bottles was compared to that of the T2Candida assay run on the T2Dx Instrument for detection of Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata, and Candida krusei, in seeded blood samples at concentrations between 3.1 and 11 CFU/mL. The BACTEC 9050 detected Candida growth in 100% of bottles (n = 20 replicates) within 5 days for all species (63.23 ± 30.27 hours), with the exception of Candida glabrata (0%). The T2Candida assay had a 100% detection rate for each species (n = 13-20 replicates) within 3 hours including C. glabrata. The sensitivity and specificity of the T2Candida assay were 1 and 0.978, respectively.

Comparison of the Bactec Fx Plus, Mycosis IC/F, Mycosis/F Lytic blood culture media and the BacT/Alert 3D FA media for detection of Candida species in seeded blood culture specimens containing therapeutic peak levels of fluconazole

BACKGROUND

The performance of Bactec Fx Plus Aerobic/F (PA), Mycosis IC/F (MF), Myco/F Lytic (ML) media and BacT/Alert 3D FA (FA) media in detecting 15 Candida isolates in blood cultures to which fluconazole had been added was investigated.

METHODS

PA with resin, MF, ML media (n = 360), and FAmedia (n = 120) were tested against Candida albicans, C. tropicalis, C. parapsilosis, and C. krusei. As the peak plasma concentration after single oral doses of fluconazole 100, 200, and 400 mg was equivalent to peak level of 1.9, 4.7, and 6.7 mg/l, respectively, corresponding fluconazole was added. Time to detection (TTD) was measured.

RESULTS

Overall TTD (mean hour ± standard deviation) for PA, FA, MF, and ML was as follows: 24.5 ± 7.3, 27.0 ± 7.5, 31.9 ± 21.3, and 37.7 ± 30.1, respectively. TTD of PA was shorter compared to other media. The effect of fluconazole was limited in PA and FA, but MF and ML showed delayed TTD. Larger inoculum size showed shorter TTDin PA and FA.

CONCLUSION

TTD of Bactec Fx Plus Aerobic/F was more than 2.5 hr faster among the tested media. As thus system and media are unaffected by added fluconazole, it could be used for the diagnosis of candidemia in the clinical settings including the patients who have been treated empirically with fluconazole at the time when blood cultures were drawn.

[Recommendations for the diagnosis of candidemia in Latin America. Grupo Proyecto Épico]

Candidemia is one of the most frequent opportunistic mycoses worldwide. Limited epidemiological studies in Latin America indicate that incidence rates are higher in this region than in the Northern Hemisphere. Diagnosis is often made late in the infection, affecting the initiation of antifungal therapy. A more scientific approach, based on specific parameters, for diagnosis and management of candidemia in Latin America is warranted. 'Recommendations for the diagnosis and management of candidemia' are a series of manuscripts that have been developed by members of the Latin America Invasive Mycosis Network. They aim to provide a set of best-evidence recommendations for the diagnosis and management of candidemia. This publication, 'Recommendations for the diagnosis of candidemia in Latin America', was written to provide guidance to healthcare professionals on the diagnosis of candidemia, as well as on the usefulness and application of susceptibility testing in patients who have a confirmed diagnosis of candidemia. Computerized searches of existing literature were performed by PubMed. The data were extensively reviewed and analyzed by members of the group. The group also met on two occasions to pose questions, discuss conflicting views, and deliberate on a series of management recommendations. 'Recommendations for the diagnosis of candidemia in Latin America' includes diagnostic methods used to detect candidemia, Candida species identification, and susceptibility testing. The availability of methods, their costs and treatment settings are considered. This manuscript is the first of this series that deals with diagnosis and treatment of invasive candidiasis. Other publications in this series include: 'Recommendations for the management of candidemia in adults in Latin America', 'Recommendations for the management of candidemia in children in Latin America', and 'Recommendations for the management of candidemia in neonates in Latin America'.

Recommendations for the diagnosis of candidemia in Latin America. Latin America Invasive Mycosis Network

Candidemia is one of the most frequent opportunistic mycoses worldwide. Limited epidemiological studies in Latin America indicate that incidence rates are higher in this region than in the Northern Hemisphere. Diagnosis is often made late in the infection, affecting the initiation of antifungal therapy. A more scientific approach, based on specific parameters, for diagnosis and management of candidemia in Latin America is warranted. 'Recommendations for the diagnosis and management of candidemia' are a series of manuscripts that have been developed by members of the Latin America Invasive Mycosis Network. They aim to provide a set of best-evidence recommendations for the diagnosis and management of candidemia. This publication, 'Recommendations for the diagnosis of candidemia in Latin America', was written to provide guidance to healthcare professionals on the diagnosis of candidemia, as well as on the usefulness and application of susceptibility testing in patients who have a confirmed diagnosis of candidemia. Computerized searches of existing literature were performed by PubMed. The data were extensively reviewed and analyzed by members of the group. The group also met on two occasions to pose questions, discuss conflicting views, and deliberate on a series of management recommendations. 'Recommendations for the diagnosis of candidemia in Latin America' includes diagnostic methods used to detect candidemia, Candida species identification, and susceptibility testing. The availability of methods, their costs and treatment settings are considered. This manuscript is the first of this series that deals with diagnosis and treatment of invasive candidiasis. Other publications in this series include: 'Recommendations for the management of candidemia in adults in Latin America', 'Recommendations for the management of candidemia in children in Latin America', and 'Recommendations for the management of candidemia in neonates in Latin America'.

Brazilian guidelines for the management of candidiasis - a joint meeting report of three medical societies: Sociedade Brasileira de Infectologia, Sociedade Paulista de Infectologia and Sociedade Brasileira de Medicina Tropical

Candida infections account for 80% of all fungal infections in the hospital environment, including bloodstream, urinary tract and surgical site infections. Bloodstream infections are now a major challenge for tertiary hospitals worldwide due to their high prevalence and mortality rates. The incidence of candidemia in tertiary public hospitals in Brazil is approximately 2.5 cases per 1000 hospital admissions. Due to the importance of this infection, the authors provide a review of the diversity of the genus Candida and its clinical relevance, the therapeutic options and discuss the treatment of major infections caused by Candida. Each topography is discussed with regard to epidemiological, clinical and laboratory diagnostic and therapeutic recommendations based on levels of evidence.

Feasibility of a novel approach for rapid detection of simulated bloodstream infections via enzymatic template generation and amplification (ETGA)-mediated measurement of microbial DNA Polymerase activity

Bloodstream infections (BSIs) caused by bacteria and fungi are associated with significant morbidity and mortality. Currently, blood culture is the gold standard for confirming a suspected BSI, but has the drawback of lengthy time-to-detection (TTD) required for indicating the presence of microbes. Detection of conserved microbial nucleic acid sequences within blood culture samples via PCR has been demonstrated to offer potential for reducing the TTD of BSI; however, these approaches have various other limitations. We report a novel approach toward rapid detection of microbes from simulated BSI via differential hematopoietic cell lysis followed by enzymatic template generation and amplification (ETGA)-mediated measurement of microbial DNA polymerase extension activity. The differential cell lysis procedure effectively reduced the level of detectable DNA polymerase extension activity associated with human-derived hematopoietic cells present in blood culture samples taken from healthy donors. After treatment with the differential cell lysis procedure, the ETGA assay detected a panel of clinically prevalent bacteria and Candida albicans from spiked blood culture samples. The ETGA blood culture method also reduced by threefold the TTD required for simulated BSI, compared with a continuous-monitoring blood culture instrument. In summary, these findings demonstrate the feasibility of an innovative approach toward a rapid, sensitive, and universal screen for microbes within blood culture samples. Potential for clinical application and automation are also addressed.

The preanalytical optimization of blood cultures: a review and the clinical importance of benchmarking in 5 Belgian hospitals

Bloodstream infections remain a major challenge in medicine. Optimal detection of pathogens is only possible if the quality of preanalytical factors is thoroughly controlled. Since the laboratory is responsible for this preanalytical phase, the quality control of critical factors should be integrated in its quality control program. The numerous recommendations regarding blood culture collection contain controversies. Only an unambiguous guideline permits standardization and interlaboratory quality control. We present an evidence-based concise guideline of critical preanalytical determinants for blood culture collection and summarize key performance indicators with their concomitant target values. In an attempt to benchmark, we compared the true-positive rate, contamination rate, and collected blood volume of blood culture bottles in 5 Belgian hospital laboratories. The true-positive blood culture rate fell within previously defined acceptation criteria by Baron et al. (2005) in all 5 hospitals, whereas the contamination rate exceeded the target value in 4 locations. Most unexpected, in each of the 5 laboratories, more than one third of the blood culture bottles were incorrectly filled, irrespective of the manufacturer of the blood culture vials. As a consequence of this shortcoming, one manufacturer recently developed an automatic blood volume monitoring system. In conclusion, clear recommendations for standardized blood culture collection combined with quality control of critical factors of the preanalytical phase are essential for diagnostic blood culture improvement.

Clinical comparison of the Bactec Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN blood culture vials for the detection of candidemia

The present study analyzed the performance of Bactec Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN vials in detection and time to detection (TTD) of Candida spp. in 179 simultaneous blood cultures. The Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN vials could detect Candida spp. in 144 (80.45%) of 179, 149 (83.24%) of 179, and 8 (4.47%) of 179 samples, respectively. With the presence of antifungal therapy, the numbers of positive vials were higher in BacT/Alert FA compared to Mycosis IC/F, 87/99 versus 73/99, respectively (P < 0.05). TTD (SD) for C. albicans was shorter in Mycosis IC/F than in BacT/Alert FA vials without antifungal therapy, 20.89 (9.33) versus 28.26 (9.77), respectively (P < 0.01). The detection of Candida spp., with concomitant bacteremia, was higher in Mycosis IC/F than in BacT/Alert FA vials, 28/30 and 19/30, respectively (P = 0.01). The present data show that the use of Bactec Mycosis IC/F together with BacT/Alert FA vials might improve the detection of Candida spp.

Diagnosis and therapy of Candida infections: joint recommendations of the German Speaking Mycological Society and the Paul-Ehrlich-Society for Chemotherapy

Invasive Candida infections are important causes of morbidity and mortality in immunocompromised and hospitalised patients. This article provides the joint recommendations of the German-speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMyKG) and the Paul-Ehrlich-Society for Chemotherapy (PEG) for diagnosis and treatment of invasive and superficial Candida infections. The recommendations are based on published results of clinical trials, case-series and expert opinion using the evidence criteria set forth by the Infectious Diseases Society of America (IDSA). Key recommendations are summarised here: The cornerstone of diagnosis remains the detection of the organism by culture with identification of the isolate at the species level; in vitro susceptibility testing is mandatory for invasive isolates. Options for initial therapy of candidaemia and other invasive Candida infections in non-granulocytopenic patients include fluconazole or one of the three approved echinocandin compounds; liposomal amphotericin B and voriconazole are secondary alternatives because of their less favourable pharmacological properties. In granulocytopenic patients, an echinocandin or liposomal amphotericin B is recommended as initial therapy based on the fungicidal mode of action. Indwelling central venous catheters serve as a main source of infection independent of the pathogenesis of candidaemia in the individual patients and should be removed whenever feasible. Pre-existing immunosuppressive treatment, particularly by glucocorticosteroids, ought to be discontinued, if feasible, or reduced. The duration of treatment for uncomplicated candidaemia is 14 days following the first negative blood culture and resolution of all associated symptoms and findings. Ophthalmoscopy is recommended prior to the discontinuation of antifungal chemotherapy to rule out endophthalmitis or chorioretinitis. Beyond these key recommendations, this article provides detailed recommendations for specific disease entities, for antifungal treatment in paediatric patients as well as a comprehensive discussion of epidemiology, clinical presentation and emerging diagnostic options of invasive and superficial Candida infections.

Comparison of BD Bactec Plus Aerobic/F medium to VersaTREK Redox 1 blood culture medium for detection of Candida spp. in seeded blood culture specimens containing therapeutic levels of antifungal agents

Recovery of Candida spp. using the BD Bactec FX blood culture (BC) system (Bactec Plus Aerobic/F medium) and the VersaTREK system (aerobic Redox medium) was evaluated using seeded BC bottles with and without the addition of commonly used antifungal agents. BC bottles (n = 1,442) were each inoculated with 10 ml human whole blood and 0.1 ml of suspensions of Candida spp., with or without antifungal agents. BC bottles were incubated in the corresponding system for a maximum of 5 days. In the absence of antifungal agents, Bactec FX recovered 97.4% of Candida spp., and VersaTREK recovered 99.1% (P = 0.154). With regard to length of time to detection (LTD) and overall recovery, both systems had various levels of effectiveness in recovering C. glabrata. In bottles containing antifungal agents, Bactec FX recovered 83.1% of isolates, whereas VersaTREK recovered 50.7% of Candida spp. (P < 0.001). For BC bottles without the addition of antifungal agents, the median LTD for VersaTREK was 2.2 h faster than that of Bactec FX (P < 0.001). In the presence of antifungal agents, the Bactec FX recovery time was significantly faster than that of VersaTREK (median difference of 10.8 h, P < 0.001). We conclude that both systems have comparable abilities to recover Candida spp. from seeded blood cultures in the absence of antifungal agents. In the presence of therapeutic levels of commonly used antifungal agents, the Bactec FX system demonstrated a significantly greater recovery of various Candida spp., as well as a shorter LTD.

Rapid and direct quantification of viable Candida species in whole blood by use of immunomagnetic separation and solid-phase cytometry

Candida species are a common source of nosocomial bloodstream infections in critically ill patients. The sensitivity of the traditional diagnostic procedure based on blood culture is variable, and it usually takes 2 to 4 days before growth of Candida species is detected. We developed a 4-h method for the quantification of Candida species in blood, combining immunomagnetic separation (IMS) with solid-phase cytometry (SPC) using viability labeling. Additionally, Candida albicans cells could be identified in real time by using fluorescent in situ hybridization. By analysis of spiked blood samples, our method was shown to be sensitive and specific, with a low detection limit (1 cell/ml of blood). In a proof-of-concept study, we applied the IMS/SPC method to 16 clinical samples and compared it to traditional blood culture. Our method proved more sensitive than culture (seven samples were positive with IMS/SPC but negative with blood culture), and identification results were in agreement. The IMS/SPC data also suggest that mixed infections might occur frequently, as C. albicans and at least one other Candida species were found in five samples. Additionally, in two cases, high numbers of cells (175 to 480 cells/ml of blood) were associated with an endovascular source of infection.

[Fungemia caused by Candida lipolytica: Speaking of two cases]

Candida lipolytica has rarely been reported as a human pathogen. We observed two cases of fungemia caused by C. lipolytica, one of them in a 12-year-old child with cystic pancreatic fibrosis in advanced phase and another in a 86-year-old woman who presented vesical neoformation with peritoneal fibrosis, bilateral hydronephrosis and recurrent urinary tract infections. After antifungal treatment and catheter removal, the fungemia appeared to be finished and blood cultures were negative.

[Epidemiology of invasive candidiasis in pediatric and adult populations]

BACKGROUND

Invasive candidiasis (IC) is the most frequent fungal disease in children and adults.

AIMS

To critically review and update the current epidemiology of Candida spp. disease in neonates, children and adults (critically ill patients and in oncohematologic patients and in solid organ transplant recipients).

METHODS

We searched the PubMed/Medline, discussing the current data.

RESULTS AND CONCLUSIONS

IC is associated with high attributable morbimortality and increased healthcare costs. In the last decades the incidence of invasive Candida spp. disease has increased in critically ill patients, has decreased in oncohematologic patients, although currently the involvement of non-albicans Candida species in the etiology of this disease is increasing steadily.

Ultra-fast low concentration detection of Candida pathogens utilizing high resolution micropore chips

Although Candida species are the fourth most common cause of nosocomial blood stream infections in the United States, early diagnostic tools for invasive candidemia are lacking. Due to an increasing rate of candidemia, a new screening system is needed to detect the Candida species in a timely manner. Here we describe a novel method of detection using a solid-state micro-scale pore similar to the operational principles of a Coulter counter. With a steady electrolyte current flowing through the pore, measurements are taken of changes in the current corresponding to the shape of individual yeasts as they translocate or travel through the pore. The direct ultra-fast low concentration electrical addressing of C. albicans has established criteria for distinguishing individual yeast based on their structural properties, which may reduce the currently used methods’ complexity for both identification and quantification capabilities in mixed blood samples.

Treatment of critically ill patients with candidemia

Early initiation of effective antimicrobial therapy is crucial for the prognosis of any infection, especially in the critically ill patient. This is particularly true in the case of candidemia. However, the earlier an empirical antimicrobial regimen is started, the greater the probability of diagnostic error and the possibility of side-effects. Recent experience of the clinical efficacy and good tolerance of echinocandins in the treatment of candidemia obliges us to review the indications for empirical antifungal treatment and the choice of antifungal agent in the critically ill patient.

Two cases of recovery of dimorphic pathogenic fungi via conventional BacT/ALERT microbial detection system media

We hereby report two instances of dimorphic fungus cultivation in BacT/ALERT-based bacteriologic media, with the first such characterization of Blastomyces dermatitidis. From a patient with disseminated coccidioidomycosis, routine blood cultures incubated on the MB/BacT 3D Microbial Detection System generated a positive signal following 75 h of incubation. B. dermatitidis was isolated from a patient hospitalized with a four-week course of respiratory illness. Organism detection from respiratory specimens via the MB/BacT 3D Mycobacteria Detection System occurred 5 days sooner than the routine fungus culture. Etiologic agents of endemic mycoses may be isolated in bacteriologic media employed by continuous monitoring instrumentation.