Epidemiological patterns of candidaemia: A comprehensive analysis over a decade

BACKGROUND

The prevalence of fungal bloodstream infections (BSI), especially candidaemia, has been increasing globally during the last decades. Fungal diagnosis is still challenging due to the slow growth of fungal microorganisms and need for special expertise. Fungal polymicrobial infections further complicate the diagnosis and extend the time required. Epidemiological data are vital to generate effective empirical treatment strategies.

OBJECTIVES

The overall aim of this project is to describe the epidemiology of monomicrobial candidaemia and polymicrobial BSI, both with mixed fungaemia and with mixed Candida/bacterial BSIs.

METHODS

We conducted a single-centre retrospective epidemiological study that encompasses 950,161 blood cultures during the years 2010 to 2020. The epidemiology of monomicrobial and polymicrobial candidaemia episodes were investigated from the electronic records.

RESULTS

We found that 1334 candidaemia episodes were identified belonging to 1144 individual patients during 2010 to 2020. Candida albicans was the most prevalent species detected in candidaemia patients, representing 57.7% of these episodes. Nakaseomyces (Candida) glabrata and Candida parapsilosis complex showed an increasing trend compared to previous studies, whereas Candida albicans demonstrated a decrease. 19.8% of these episodes were polymicrobial and 17% presented with mixed Candida/bacterial BSIs while 2.8% were mixed fungaemia. C. albicans and N. glabrata were the most common combination (51.4%) in mixed fungaemia episodes. Enterococcus and Lactobacillus spp. were the most common bacteria isolated in mixed Candida/bacterial BSIs.

CONCLUSIONS

Polymicrobial growth with candidaemia is common, mostly being mixed Candida/bacterial BSIs. C. albicans was detected in more than half of all the candidaemia patients however showed a decreasing trend in time, whereas an increase is noteworthy in C. parapsilosis complex and N. glabrata.

Performance of an innovative culture-based digital dipstick for detection of bacteriuria

IMPORTANCE

In this study, we explore the transformative potential of UTI-lizer, an emerging technology not yet commercially available. Our manuscript shows that UTI-lizer is a promising alternative for detecting the five main pathogens that cause urinary tract infections (UTIs). The results also indicate that digital dipsticks have the potential to uniquely provide UTI diagnostic quality on par with that of gold-standard testing, with the added benefits of ease of testing, rapid test handling time, and simple test equipment. This technology can be helpful in quickly ruling out bacterial infections and reducing the unnecessary use of antibiotics, especially in primary care settings or at the point of care. Moreover, the UTI-lizer test can reduce the number of negative urine samples sent to central laboratories, thus easing the burden of UTI diagnostics on the healthcare system. We believe our study, as well as current and upcoming research based on this technology, is highly relevant for clinical microbiologists, microbiology scientists, general practitioners, and urologists.

ChatGPT (GPT-3.5) as an assistant tool in microbial pathogenesis studies in Sweden: a cross-sectional comparative study

ChatGPT (GPT-3.5) has entered higher education and there is a need to determine how to use it effectively. This descriptive study compared the ability of GPT-3.5 and teachers to answer questions from dental students and construct detailed intended learning outcomes. When analyzed according to a Likert scale, we found that GPT-3.5 answered the questions from dental students in a similar or even more elaborate way compared to the answers that had previously been provided by a teacher. GPT-3.5 was also asked to construct detailed intended learning outcomes for a course in microbial pathogenesis, and when these were analyzed according to a Likert scale they were, to a large degree, found irrelevant. Since students are using GPT-3.5, it is important that instructors learn how to make the best use of it both to be able to advise students and to benefit from its potential.

European candidaemia is characterised by notable differential epidemiology and susceptibility pattern: Results from the ECMM Candida III study

The objectives of this study were to assess Candida spp. distribution and antifungal resistance of candidaemia across Europe. Isolates were collected as part of the third ECMM Candida European multicentre observational study, conducted from 01 to 07-07-2018 to 31-03-2022. Each centre (maximum number/country determined by population size) included ∼10 consecutive cases. Isolates were referred to central laboratories and identified by morphology and MALDI-TOF, supplemented by ITS-sequencing when needed. EUCAST MICs were determined for five antifungals. fks sequencing was performed for echinocandin resistant isolates. The 399 isolates from 41 centres in 17 countries included C. albicans (47.1%), C. glabrata (22.3%), C. parapsilosis (15.0%), C. tropicalis (6.3%), C. dubliniensis and C. krusei (2.3% each) and other species (4.8%). Austria had the highest C. albicans proportion (77%), Czech Republic, France and UK the highest C. glabrata proportions (25-33%) while Italy and Turkey had the highest C. parapsilosis proportions (24-26%). All isolates were amphotericin B susceptible. Fluconazole resistance was found in 4% C. tropicalis, 12% C. glabrata (from six countries across Europe), 17% C. parapsilosis (from Greece, Italy, and Turkey) and 20% other Candida spp. Four isolates were anidulafungin and micafungin resistant/non-wild-type and five resistant to micafungin only. Three/3 and 2/5 of these were sequenced and harboured fks-alterations including a novel L657W in C. parapsilosis. The epidemiology varied among centres and countries. Acquired echinocandin resistance was rare but included differential susceptibility to anidulafungin and micafungin, and resistant C. parapsilosis. Fluconazole and voriconazole cross-resistance was common in C. glabrata and C. parapsilosis but with different geographical prevalence.

Mycobiota profile of oral fungal infections in head and neck cancer patients receiving radiotherapy: A 6-year retrospective MALDI-TOF mass spectrometry study

OBJECTIVES

Head and neck cancer (HNC) impairs patient immunity and increases susceptibility to oral fungal infections (OFIs). Effectively treating such infections requires accurate identification of the causative pathogens. This study aimed to characterize the mycobiota profile of OFIs in HNC patients undergoing radiation treatment (RT).

MATERIALS AND METHODS

A 6-year retrospective analysis of oral mucosal samples from HNC patients with a history of RT and OFIs between 2014 and 2019 was conducted using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) profiling. Samples from the Clinical Microbiology Laboratory at Karolinska University Hospital were evaluated for mycobiota diversity and species co-occurrence patterns in the ongoing-RT and post-RT groups.

RESULTS

A total of 190 oral fungi (88% Candida, 5% Pichia) were isolated from 162 HNC patients receiving RT. In the ongoing-RT group, the emergent non-albicans Candida (NAC) species; F. solani and C. jadinii, were detected for the first time. The dominant pathogens in both ongoing and post-RT groups were C. albicans, C. glabrata, P. kudriavzevii, C. parapsilosis, and C. tropicalis, as shown by Venn analysis. Network analysis revealed greater fungi diversity and multi-species co-occurrence in the ongoing-RT group. C. albicans commonly co-occurred with C. glabrata in both ongoing-RT (21%) and post-RT groups (30%).

CONCLUSION

MALDI-TOF MS identified a wide range of oral fungal species in HNC patients receiving RT. While C. albicans remains the most prevalent OFIs pathogen, multi-species co-occurrence and novel NACs were noted. Understanding the ecological interactions among these causative pathogens could significantly advance the development of effective therapeutics for treating OFIs in HNC patients.

Analytical Performance and Potential Clinical Utility of EUCAST Rapid Antimicrobial Susceptibility Testing in Blood Cultures after Four Hours of Incubation

EUCAST rapid antimicrobial susceptibility testing (RAST) provides antibiotic susceptibility results after 4 to 8 h of incubation. This study assessed the diagnostic performance and clinical usefulness of EUCAST RAST after 4 h. This was a retrospective clinical study performed on blood cultures with Escherichia coli and Klebsiella pneumoniae complex (K. pneumoniae and Klebsiella variicola) at Karolinska University Laboratory (Stockholm, Sweden). The rate of categorized RAST results and the categorical agreement (CA) of RAST with the standard EUCAST 16-to-20-h disk diffusion (DD) method for piperacillin-tazobactam, cefotaxime, ceftazidime, meropenem, and ciprofloxacin were analyzed, as well as the utility of RAST for adjusting the empirical antibiotic therapy (EAT) and the combination of RAST with a lateral flow assay (LFA) for extended-spectrum β-lactamase (ESBL) detection. A total of 530 E. coli and 112 K. pneumoniae complex strains were analyzed, generating 2,641 and 558 readable RAST zones, respectively. RAST results categorized according to antimicrobial sensitivity/resistance (S/R) were obtained for 83.1% (2,194/2,641) and 87.5% (488/558) of E. coli and K. pneumoniae complex strains, respectively. The RAST result categorization to S/R for piperacillin-tazobactam was poor (37.2% for E. coli and 66.1% for K. pneumoniae complex). CA with the standard DD method was over 97% for all tested antibiotics. Using RAST, we detected 15/26 and 1/10 of the E. coli and K. pneumoniae complex strains that were resistant to the EAT. For patients treated with cefotaxime, RAST was used to detect 13/14 cefotaxime-resistant E. coli strains and 1/1 cefotaxime-resistant K. pneumoniae complex strain. ESBL positivity was reported the same day as blood culture positivity with RAST and LFA. EUCAST RAST provides accurate and clinically relevant susceptibility results after 4 h of incubation and can accelerate the assessment of resistance patterns. IMPORTANCE Early effective antimicrobial treatment has been shown to be crucial for improving the outcome of bloodstream infections (BSI) and sepsis. In combination with the rise of antibiotic resistance, this calls for accelerated methods for antibiotic susceptibility testing (AST) for effective treatment of BSI. This study assesses EUCAST RAST, an AST method that yields results in 4, 6, or 8 h after blood culture positivity. We analyzed a high number of clinical samples of Escherichia coli and Klebsiella pneumoniae complex strains and confirm that the method delivers reliable results after 4 h of incubation for the relevant antibiotics for treating E. coli and K. pneumoniae complex bacteremia. Furthermore, we conclude that it is an important tool for antibiotic treatment decision-making and early detection of ESBL-producing isolates.

The current state of laboratory mycology and access to antifungal treatment in Europe: a European Confederation of Medical Mycology survey

Access to the appropriate tools is crucial for early diagnosis and clinical management of invasive fungal infections. This Review aims to describe the invasive fungal infection diagnostic capacity of Europe to better understand the status and the most pressing aspects that need improvement. To our knowledge, this is the first time that the mycological diagnostic capability and access to antifungal treatments of institutions has been evaluated at a pan-European level. Between Nov 1, 2021, and Jan 31, 2022, 388 institutions in Europe self-assessed their invasive fungal infection management capability. Of the 388 participating institutions from 45 countries, 383 (99%) had access to cultures, 375 (97%) to microscopy, 363 (94%) to antigen-detection assays, 329 (85%) to molecular tests (mostly PCR), and 324 (84%) to antibody tests for diagnosis and management. With the exception of microscopy, there were considerable differences in access to techniques among countries according to their gross domestic product. At least one triazole was available in 363 (94%) of the institutions, one echinocandin in 346 (89%), and liposomal amphotericin B in 301 (78%), with country gross domestic product-based differences. Differences were also observed in the access to therapeutic drug monitoring. Although Europe is well prepared to manage invasive fungal infections, some institutions do not have access to certain diagnostic tools and antifungal drugs, despite most being considered essential by WHO. These limitations need to be overcome to ensure that all patients receive the best diagnostic and therapeutic management.

Clinical Microbial Identification of Severe Oral Infections by MALDI-TOF Mass Spectrometry in Stockholm County: an 11-Year (2010 to 2020) Epidemiological Investigation

Growing evidence suggests that oral infections can modify the course of systemic diseases. To date, epidemiological data on microbial oral infections are scarce. Here, we performed a comprehensive analysis of the trend and microbial diversity in oral infection specimens referred for clinical microbiology analysis from 2010 to 2020. The microbes were isolated by culture and were identified via matrix-assisted laser desorption ionization-time of flight mass spectrometry technology (MALDI-TOF MS) throughout the study period. A total of 1,014 referred samples from dental clinics in Stockholm County with dentoalveolar abscesses and jaw osteomyelitis being the main reason were identified. Overall, the microbial composition was dominated by Firmicutes (51%), followed by Bacteroidetes (19%), Proteobacteria (12%), and Actinobacteria (5%). At the genus level, Streptococcus spp. (36%), Prevotella spp. (18%), and Staphylococcus spp. (11%) were among the most frequently reported. Interestingly, a strong increase in trend was noted for Streptococcus anginosus, Streptococcus mitis, Streptococcus sanguinis, Eikenella corrodens, Actinomyces spp., Aggregatibacter aphrophilus, Staphylococcus epidermidis, and Granulicatella adiacens during the study time (R = 0.66 to 0.89, P < 0.05), and a minor increase was noted for Enterococcus faecalis and Klebsiella spp., whereas steady levels were noted for most of the others. The present study shows the diversity of bacteria that have been involved in dental infections during the last decade in the capital of Sweden, as well as the emerging oral microbiota trend, with clear clinical implications on the oral-systemic link. IMPORTANCE Oral diseases and associated microbes are a risk factor for systemic diseases and can change the courses of these diseases. To date, epidemiological data on microbial oral infections are scarce, and longitudinal reports are lacking. We present for the first time the microbial composition of severe oral bacterial infections determined via the MALDI-TOF mass spectrometry technique in a comprehensive study between 2010 and 2020 (11 years) in Stockholm County. The trend and microbial diversity of oral infections were analyzed on referred clinical microbiological samples and were processed by standardized protocols. Trend increase was noted for Streptococcus anginosus, Streptococcus mitis, Streptococcus sanguinis, Eikenella corrodens, Actinomyces spp., Aggregatibacter aphrophilus, Staphylococcus epidermidis, Granulicatella adiacens, Enterococcus faecalis, and Klebsiella spp. Our results provide new insights into the diversity and trend of oral microbiota that were involved in serious oral infections over the past decade in the capital of Sweden and may influence the oral-systemic link.

[Four blood culture bottles from one venipuncture instead of divided into two: new Swedish national recommendation for blood culture]

Blood culture is the standard method for microbiological diagnostics in sepsis. In many countries, the traditional recommendation for blood culture has been collection of four blood culture bottles with two bottles from each of two venipunctures. New studies show that four blood culture bottles from the same venipuncture provides similar culture results and higher number of obtained blood culture bottles, than the traditional method. Thus, new national recommendations recommend collection of four blood culture bottles from the same venipuncture as the routine blood culture method in Sweden.

Photo-oxidative stress response and virulence traits are co-regulated in E. faecalis after antimicrobial photodynamic therapy

Knowledge of photo-oxidative stress responses in bacteria that survive antimicrobial photodynamic therapy (aPDT) is scarce. Whereas aPDT is attracting growing clinical interest, subsequent stress responses are crucial to evaluate as they may lead to the up-regulation of pathogenic traits. Here, we aimed to assess transcriptional responses to sublethal aPDT-stress and identify potential connections with virulence-related genes. Six Enterococcus faecalis strains were investigated; ATCC 29212, three dental root-canal isolates labelled UmID1, UmID2 and UmID3 and two vancomycin-resistant isolates labelled A1 and A2. TMPyP was employed as a photosensitiser. A viability dose-response curve to increasing concentrations of TMPyP was determined by culture plating. Differential expression of genes involved in oxidative stress responses (dps and hypR), general stress responses (dnaK, sigma-factor^V and relA), virulence-related genes (ace, fsrC and gelE) and vancomycin-resistance (vanA) was assessed by reverse-transcription qPCR. TMPyP-mediated aPDT inactivated all strains with comparable efficiencies. TMPyP at 0.015 μM was selected to induce sublethal photo-oxidative stress. Despite heterogeneities in gene expression between strains, transcriptional profiles revealed up-regulations of transcripts dps, hypR as well as dnaK and sigma factor^V after exposure to TMPyP alone and to light-irradiated TMPyP. Specifically, the alternative sigma factor^V reached up to 39 ± 113-fold (median ± IQR) (p = 0.0369) in strain A2. Up-regulation of the quorum sensing operon, fsr, and its downstream virulence-related gelatinase gelE were also observed in strains ATCC-29212, A1, A2 and UmID3. Finally, photo-oxidative stress induced vanA-type vancomycin-resistance gene in both carrier isolates, reaching up to 3.3 ± 17-fold in strain A2 (p = 0.015). These findings indicate that, while aPDT successfully inactivates vancomycin-resistant and naïve strains of E. faecalis, subpopulations of surviving cells respond by co-ordinately up-regulating a network of genes involved in stress survival and virulence. This includes the induction of vancomycin-resistance genes in carrier isolates. These data may provide the mechanistic basis to circumvent bacterial responses and improve future clinical protocols.

Evaluation of an extracorporeal ozone-based bactericide system for the treatment of Escherichia coli sepsis

BACKGROUND

Sepsis is associated with substantial mortality rates. Antibiotic treatment is crucial, but global antibiotic resistance is now classified as one of the top ten global public health risks facing humanity. Ozone (O₃) is an inorganic molecule with no evident function in the body. We investigated the bactericide properties of ozone, using a novel system of extracorporeal ozone blood treatment. We hypothesized that ozone would decrease the concentration of viable Escherichia coli (E. coli) in human whole blood and that the system would be technically feasible and physiologically tolerable in a clinically relevant model of E. coli sepsis in swine.

METHODS

The E. coli strain B09-11822, a clinical isolate from a patient with septic shock was used. The in vitro study treated E. coli infected human whole blood (n = 6) with ozone. The in vivo 3.5-h sepsis model randomized swine to E. coli infusion and ozone treatment (n = 5) or E. coli infusion and no ozone treatment (n = 5). Live E. coli, 5 × 10⁷ colony-forming units (CFU/mL) was infused in a peripheral vein. Ozone treatment was initiated with a duration of 30 min after 1.5 h.

RESULTS

The single pass in vitro treatment decreased E. coli by 27%, mean 1941 to 1422 CFU/mL, mean of differences - 519.0 (95% CI - 955.0 to - 82.98, P = 0.0281). pO₂ increased (95% CI 31.35 to 48.80, P = 0.0007), pCO₂ decreased (95% CI - 3.203 to - 1.134, P = 0.0069), oxyhemoglobin increased (95% CI 1.010 to 3.669, P = 0.0113). Methemoglobin was not affected. In the sepsis model, 9/10 swine survived. One swine randomized to ozone treatment died from septic shock before initiation of the treatment. Circulatory, respiratory, and metabolic parameters were not affected by the ozone treatment. E. coli in arterial blood, in organs and in aerobic and anaerobic blood cultures did not differ. Hemoglobin, leucocytes, and methemoglobin were not affected by the treatment.

CONCLUSIONS

Ozone decreased the concentration of viable E. coli in human whole blood. The system was technically feasible and physiologically tolerable in porcine sepsis/septic shock and should be considered for further studies towards clinical applications.

Isolation of pancreatic microbiota from cystic precursors of pancreatic cancer with intracellular growth and DNA damaging properties

Emerging research suggests gut microbiome may play a role in pancreatic cancer initiation and progression, but cultivation of the cancer microbiome remains challenging. This pilot study aims to investigate the possibility to cultivate pancreatic microbiome from pancreatic cystic lesions associated with invasive cancer. Intra-operatively acquired pancreatic cyst fluid samples showed culture-positivity mainly in the intraductal papillary mucinous neoplasm (IPMN) group of lesions. MALDI-TOF MS profiling analysis shows Gammaproteobacteria and Bacilli dominate among individual bacteria isolates. Among cultivated bacteria, Gammaproteobacteria, particularly Klebsiella pneumoniae, but also Granulicatella adiacens and Enterococcus faecalis, demonstrate consistent pathogenic properties in pancreatic cell lines tested in ex vivo co-culture models. Pathogenic properties include intracellular survival capability, cell death induction, or causing DNA double-strand breaks in the surviving cells resembling genotoxic effects. This study provides new insights into the role of the pancreatic microbiota in the intriguing link between pancreatic cystic lesions and cancer.

Correlation of clinical sepsis definitions with microbiological characteristics in patients admitted through a sepsis alert system; a prospective cohort study

Background

Sepsis was recently redefined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. With this redefinition (Sepsis-3), clinical and microbiological characteristics of patients with sepsis may differ from the patients fulfilling the previous definition (Sepsis-2).

Purpose

To describe differences in clinical and microbiological characteristics of sepsis episodes between Sepsis-3 and Sepsis-2. The secondary aim was to compare blood culture outcomes between episodes fulfilling Sepsis-3 and Sepsis-2 criteria, respectively.

Methods

A prospective study design was used to include patients presenting with clinically suspected sepsis in the emergency department. Six blood culture bottles were collected from each patient. Blood cultures were described as having clinically relevant growth, contaminant growth, or no growth. Clinical and laboratory data were collected from medical records and the laboratory information system.

Results

The analysis included 514 episodes. There were 357/514 (79.5%) Sepsis-3 and 411/514 (80.0%) Sepsis-2 episodes. In total, 341/514 (66.3%) episodes fulfilled both Sepsis-3 and Sepsis-2 criteria. Blood cultures were positive for clinically relevant growth in 130/357 (36.1%) and 145/411 (35.3%) episodes in Sepsis-3 and Sepsis-2, respectively. Other clinical and microbiological characteristics did not differ between Sepsis-3 and Sepsis-2.

Conclusions

A high proportion of patients included through a sepsis alert system fulfilled both Sepsis-3 and Sepsis-2 criteria. The performance of blood cultures in detection of microorganisms was poor and were similar in Sepsis-3 and Sepsis-2 patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-022-00498-3.

Secondary bacterial infections and antimicrobial resistance in COVID-19: comparative evaluation of pre-pandemic and pandemic-era, a retrospective single center study

PURPOSE

In this study, we aimed to evaluate the epidemiology and antimicrobial resistance (AMR) patterns of bacterial pathogens in COVID-19 patients and to compare the results with control groups from the pre-pandemic and pandemic era.

METHODS

Microbiological database records of all the COVID-19 diagnosed patients in the Ege University Hospital between March 15, 2020, and June 15, 2020, evaluated retrospectively. Patients who acquired secondary bacterial infections (SBIs) and bacterial co-infections were analyzed. Etiology and AMR data of the bacterial infections were collected. Results were also compared to control groups from pre-pandemic and pandemic era data.

RESULTS

In total, 4859 positive culture results from 3532 patients were analyzed. Fifty-two (3.59%) patients had 78 SBIs and 38 (2.62%) patients had 45 bacterial co-infections among 1447 COVID-19 patients. 22/85 (25.88%) patients died who had bacterial infections. The respiratory culture-positive sample rate was 39.02% among all culture-positive samples in the COVID-19 group. There was a significant decrease in extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales (8.94%) compared to samples from the pre-pandemic (20.76%) and pandemic era (20.74%) (p = 0.001 for both comparisons). Interestingly, Acinetobacter baumannii was the main pathogen in the respiratory infections of COVID-19 patients (9.76%) and the rate was significantly higher than pre-pandemic (3.49%, p < 0.002) and pandemic era control groups (3.11%, p < 0.001).

CONCLUSION

Due to the low frequency of SBIs reported during the ongoing pandemic, a more careful and targeted antimicrobial prescription should be taken. While patients with COVID-19 had lower levels of ESBL-producing Enterobacterales, the frequency of multidrug-resistant (MDR) A. baumannii is higher.

A biliary immune landscape map of primary sclerosing cholangitis reveals a dominant network of neutrophils and tissue-resident T cells

The human biliary system, a mucosal barrier tissue connecting the liver and intestine, is an organ often affected by serious inflammatory and malignant diseases. Although these diseases are linked to immunological processes, the biliary system represents an unexplored immunological niche. By combining endoscopy-guided sampling of the biliary tree with a high-dimensional analysis approach, comprehensive mapping of the human biliary immunological landscape in patients with primary sclerosing cholangitis (PSC), a severe biliary inflammatory disease, was conducted. Major differences in immune cell composition in bile ducts compared to blood were revealed. Furthermore, biliary inflammation in patients with PSC was characterized by high presence of neutrophils and T cells as compared to control individuals without PSC. The biliary T cells displayed a CD103⁺CD69⁺ effector memory phenotype, a combined gut and liver homing profile, and produced interleukin-17 (IL-17) and IL-22. Biliary neutrophil infiltration in PSC associated with CXCL8, possibly produced by resident T cells, and CXCL16 was linked to the enrichment of T cells. This study uncovers the immunological niche of human bile ducts, defines a local immune network between neutrophils and biliary-resident T cells in PSC, and provides a resource for future studies of the immune responses in biliary disorders.

Comparison of Four Streptococcus pneumoniae Urinary Antigen Tests Using Automated Readers

Streptococcus pneumoniae urinary antigen tests (UATs) may be interpreted using automatic readers to potentially automate sample incubation and provide standardized results reading. Here, we evaluated four UATs the BinaxNOW S. pneumoniae Antigen Card (Abbott, Chicago, IL, USA), ImmuView S. pneumoniae and Legionella (SSI Diagnostica, Hillerød, Denmark), STANDARD F S. pneumoniae Ag FIA (SD Biosensor, Gyeonggi, South Korea), and Sofia S. pneumoniae FIA (Quidel Corporation, San Diego, CA, USA) with their respective benchtop readers for their ability to detect S. pneumoniae urinary antigen. We found that these assays had a sensitivity of 76.9–86.5%, and specificity of 84.2–89.7%, with no significant difference found among the four UATs. The assays had a high level of agreement with each other, with 84.5% of samples testing consistently across all four assays. The automatically and visually read test results from the two immunochromatographic assays, BinaxNOW and ImmuView, were compared and showed excellent agreement between the two types of reading. Immunofluorescent-based assays, Sofia and STANDARD F, had significantly less time to detect compared to the two immunochromatographic assays due to having less assay setup procedures and shorter sample incubation times. In conclusion, the four UATs performed similarly in the detection of S. pneumoniae urinary antigen, and readers can bring increased flexibility to running UATs in the clinical routine.

Human endometrial MAIT cells are transiently tissue resident and respond to Neisseria gonorrhoeae

Mucosa-associated invariant T (MAIT) cells are non-classical T cells important in the mucosal defense against microbes. Despite an increasing interest in the immunobiology of the endometrial mucosa, little is known regarding human MAIT cells in this compartment. The potential role of MAIT cells as a tissue-resident local defense against microbes in the endometrium is largely unexplored. Here, we performed a high-dimensional flow cytometry characterization of MAIT cells in endometrium from pre- and postmenopausal women, and in decidua from first-trimester pregnancies. Furthermore, we assessed MAIT cell function by stimulation with Neisseria gonorrhoeae (N. gonorrhoeae). Endometrial MAIT (eMAIT) cells represented a stable endometrial immune cell population as limited dynamic changes were observed during the menstrual cycle, post menopause, or in response to pregnancy. Furthermore, eMAIT cells exhibited an activated tissue-resident phenotype. Despite expressing CD69 and CD103, eMAIT cells were replenished over time by circulating MAIT cells, as assessed using human uterus transplantation as a model. Finally, functional experiments revealed the capability of MAIT cells to respond to the sexually transmitted and tissue-relevant pathogen, N. gonorrhoeae. In conclusion, our study provides novel insight into human MAIT cell dynamics and anti-microbial properties in the human uterus.

Identification of microorganisms directly from blood culture bottles with polymicrobial growth: comparison of FilmArray and direct MALDI-TOF MS

Bloodstream infections (BSIs) are related to high mortality and morbidity. Rapid administration of effective antimicrobial treatment is crucial for patient survival. Recently developed rapid methods to identify pathogens directly from blood culture bottles speed up diagnosis of BSIs. The present study compares the performance of two rapid identification methods, FilmArray and direct MALDI-TOF MS, on identifying microorganisms directly from positive blood culture bottles with polymicrobial growth. FilmArray and direct MALDI-TOF MS were performed directly on positive clinical and simulated polymicrobial blood culture bottles. Assay results were compared with standard culture methods. In total, 110 polymicrobial blood culture samples, of which 96 samples contained two microorganisms while 14 samples contained three microorganisms, were studied. FilmArray was able to identify 215/234 (92.0%) of isolates detected by the standard culture method and successfully identified all microorganisms in 88/110 (80.0%) of blood culture bottles. In contrast, direct MALDI-TOF MS was only able to identify 65/234 (27.8%) of isolates and managed to identify all microoganisms in 2/110 (2.1%) of blood culture bottles. FilmArray is a rapid method for direct identification of polymicrobial blood culture samples that can complement the conventional identification methods. Direct MALDI-TOF MS has low performance with polymicrobial samples.

Low prevalence of bloodstream infection and high blood culture contamination rates in patients with COVID-19

PURPOSE

In the management of COVID-19, knowledge is lacking on the frequency of secondary bacterial infections and on how empirical antibiotic therapy should be used. In the present study, we aimed to compare blood culture (BC) results of a COVID-19 patient cohort with two cohorts of patients without detected COVID-19.

METHODS

Using a retrospective cohort study design of patients subjected to BC in six tertiary care hospitals, SARS-CoV-2 positive patients from March 1 to April 30 in 2020 (COVID-19 group) were compared to patients without confirmed SARS-CoV-2 during the same period (control group-2020) and with patients sampled March 1 to April 30 in 2019 (control group-2019). The outcomes studied were proportion of BC positivity, clinically relevant growth, and contaminant growth.

RESULTS

In total 15,103 patients and 17,865 BC episodes were studied. Clinically relevant growth was detected in 197/3,027 (6.5%) BC episodes in the COVID-19 group compared to 717/6,663 (10.8%) in control group-2020 (p<0.0001) and 850/8,175 (10.4%) in control group-2019 (p<0.0001). Contamination was present in 255/3,027 (8.4%) BC episodes in the COVID-19 group compared to 330/6,663 (5.0%) in control group-2020 (p<0.0001) and 354/8,175 (4.3%) in control group-2019 (p<0.0001).

CONCLUSION

In COVID-19 patients, the prevalence of bloodstream bacterial infection is low and the contamination rate of BC is high. This knowledge should influence guidelines regarding blood culture sampling and empirical antibiotic therapy in COVID-19 patients.

Circulating and Salivary Antibodies to Fusobacterium nucleatum Are Associated With Cystic Pancreatic Neoplasm Malignancy

Objectives

Intraductal papillary mucinous neoplasms (IPMNs) are cystic precursor lesions to pancreatic cancer. The presence of oral microbes in pancreatic tissue or cyst fluid has been associated with high-grade dysplasia (HGD) and cancer. The present study aims at investigating if humoral immunity to pancreas-associated oral microbes reflects IPMN severity.

Design

Paired plasma (n = 109) and saliva (n = 65) samples were obtained from IPMN pancreatic cystic tumor cases and controls, for anti-bacterial antibody analysis and DNA quantification by enzyme-linked immunosorbent assay (ELISA) and qPCR, respectively. Tumor severity was graded by histopathology, laboratory, and clinical data. Circulating plasma and salivary antibody reactivity to a pancreas-associated oral microbe panel were measured by ELISA and correlated to tumor severity.

Results

The patient group with high-risk cystic tumors (HGD and/or associated invasive cancer) shows ample circulating IgG reactivity to Fusobacterium nucleatum (F. nucleatum) but not to Granulicatella adiacens (G. adiacens), which is independent of the salivary bacteria DNA levels. This group also shows higher salivary IgA reactivity to F. nucleatum, Fap2 of F. nucleatum, and Streptococcus gordonii (S. gordonii) compared to low-risk IPMN and controls. The salivary antibody reactivity to F. nucleatum and Fap2 are found to be highly correlated, and cross-competition assays further confirm that these antibodies appear cross-reactive.

Conclusion

Our findings indicate that humoral reactivity against pancreas-associated oral microbes may reflect IPMN severity. These findings are beneficial for biomarker development.

The impact of delayed analysis of positive blood cultures on the performance of short-term culture followed by MALDI-TOF MS

BACKGROUND

Short-term culture followed by MALDI-TOF MS is one of the most widely used methods for fast identification of microorganisms from blood cultures. The method identifies the vast majority of bloodstream infection pathogens in 2-6 h after positive blood culture. Transport time of blood culture bottles to laboratories is a major problem affecting total turnaround time. Therefore, many central laboratories establish satellite blood culture systems in other clinics and hospitals to allow blood culture bottles to be incubated immediately after sampling. However, positive blood culture bottles still need to be transported to the clinical microbiology laboratory for analysis. The aim of this study was to investigate how delayed analysis of positive blood culture bottles would affect the short-term culture followed by MALDI-TOF MS method.

MATERIALS/METHODS

To simulate the effect of transportation and delayed analysis of blood culture bottles, 51 simulated blood culture bottles were incubated for 0, 2, 4 and 24 h at room temperature. After each time interval, a 2 to 4 h short-term culture followed by MALDI-TOF MS was performed. In addition, 257 prospective clinical positive blood culture bottles were analysed with the same method after a 24 h incubation at room temperature.

RESULTS

In simulated samples, all (120/120) Gram-negative bacteria and 77/84 (91.6%) Gram-positive bacteria were accurately identified at species-level after a 2 h short-term culture, regardless of the duration of simulated transport time. In the clinical samples, 100/116 (86.2%) Gram-negative, and 44/141 (31.2%) Gram-positive bacteria were accurately identified at species-level after a 2 h short-term culture. After contaminants were excluded, 39/71 (54.9%) Gram-positive bacteria could be identified after 2 h. After a 4 h short-term culture, 112/116 (96.6%) Gram-negative, and 108/141 (76.6%) Gram-positive bacteria were accurately identified at species-level. Of the clinically relevant Gram-positive bacteria, 68/71 (95.8%) were identified at species-level after 4 h.

CONCLUSIONS

Short-term culture followed by MALDI-TOF MS can provide fast and accurate results for identification of clinically relevant bacteria, despite long transportation times from satellite laboratories. The present data shows that the method can be used for identification of microorganisms from positive blood cultures transported from satellite blood culture systems.

Single-Sampling Strategy vs. Multi-Sampling Strategy for Blood Cultures in Sepsis: A Prospective Non-inferiority Study

Background

Optimal sampling is critical for the performance of blood cultures (BCs). Most guidelines recommend collecting 40 ml of blood, divided between two venipuncture sites, i.e., multi-sampling strategy (MSS). Sampling through a single venipuncture site, i.e., single-sampling strategy (SSS) is easier; however, the diagnostic performance of SSS compared to MSS remains unknown. Thus, we aimed to study if SSS is non-inferior to MSS for detection of pathogenic microorganisms.

Methods

A prospective, paired, non-inferiority design was used. Patients with clinically suspected sepsis admitted to an Emergency Department were included. Six BC bottles were simultaneously collected, consisting of four BC bottles from the first arm and two from the other arm. SSS consisted of BC bottles 1, 2, 3, and 4, and MSS consisted of BC bottles 1, 2, 5, and 6. Samples were incubated in a BacT/ALERT BC system.

Results

The final analysis included 549 episodes. Pathogenic microorganisms were detected in 162 cases (29.5%) with MSS and 160 cases (29.1%) with SSS, yielding an absolute difference of 0.36%, with a 95% confidence interval of -1.33 to 2.06%, which did not exceed the predefined non-inferiority margin of 5%. MSS tended to produce more contaminant growth (7.3% of cases) than SSS (5.3% of cases; p = 0.072).

Conclusion

The study showed that SSS was non-inferior to MSS in detecting pathogenic microorganisms and supports the use of SSS as a routine method.

Rapid microbial identification and antimicrobial susceptibility testing to drive better patient care: an evolving scenario

Antimicrobial chemotherapy for septic patients begins with empirical therapy and can be subsequently revised when the results of microbiological testing become available. In recent years, a number of novel technologies for the microbiological diagnosis of sepsis have been developed that return results in a shorter timeframe compared with conventional diagnostic approaches. These novel technologies aid antimicrobial stewardship when treating septic patients by reducing the time to appropriate antimicrobial chemotherapy. Advantages and limitations of these technologies should be well understood upon their introduction in the diagnostic workflow. Increasingly popular DNA-based technologies primarily focus on the rapid identification of pathogens, but information on antimicrobial susceptibility is lacking or limited to a few clinically relevant resistance markers. Thus, DNA-based molecular techniques can complement conventional technologies but cannot replace them. On the other hand, a novel technology that provides both rapid identification of bacterial pathogens and a rapid phenotypic antibiogram with MIC values, and which starts from positive blood cultures, is a very promising approach for fast diagnosis of sepsis. To fully leverage the advantages offered by novel diagnostic technologies for sepsis requires a careful introduction into the laboratory workflow, following an evaluation by a health technology assessment approach. It may also require some reshaping of the workflow (e.g. to process the positive blood cultures on a 24/7 schedule) and of the laboratory organization (e.g. by creating a laboratory subsection for fast diagnosis of sepsis).

Identification and antimicrobial susceptibility testing of Gram-positive and Gram-negative bacteria from positive blood cultures using the Accelerate Pheno™ system

Rapid identification and antimicrobial susceptibility testing remain a crucial step for early efficient therapy of bloodstream infections. Traditional methods require turnaround times of at least 2 days, while rapid procedures are often associated with extended hands-on time. The Accelerate Pheno™ System provides microbial identification results within 90 min and susceptibility data in approximately 7 h directly from positive blood cultures with only few minutes of hands-on time. The aim of this study was, therefore, to evaluate the performance of the Accelerate Pheno™ System in identification and antimicrobial susceptibility testing of both Gram-positive and Gram-negative bacteria directly from clinical blood culture samples. We analyzed 108 and 67 blood culture bottles using the Accelerate PhenoTest™ BC kit with software version v1.0 and the FDA-cleared version v1.2, respectively. Reliable identification was achieved for Enterobacteriaceae, staphylococci, and enterococci, with 76/80 (95%), 42/46 (91%), and 10/11 (91%) correct identifications. Limitations were observed in the identification of streptococci, including Streptococcus pneumoniae and Streptococcus pyogenes, and coagulase-negative staphylococci. Antimicrobial susceptibility results for Enterobacteriaceae, for amikacin, ertapenem, ciprofloxacin, gentamicin, meropenem, and piperacillin-tazobactam ranged between 86 and 100% categorical agreement. Using v1.2, results for ceftazidime showed 100% concordance with the reference method. For staphylococci, the overall performance reached 92% using v1.2. Qualitative tests for detection of methicillin or macrolide-lincosamide-streptogramin B (MLSB) resistance caused major and very major errors for isolates. Overall, the present data show that the Accelerate Pheno™ system can, in combination with Gram stain, be used as a rapid complementation to standard microbial diagnosis of bloodstream infections.

Demise of Polymerase Chain Reaction/Electrospray Ionization-Mass Spectrometry as an Infectious Diseases Diagnostic Tool

Although there are several US Food and Drug Administration (FDA)-approved/cleared molecular microbiology diagnostics for direct analysis of patient samples, all are single target or panel-based tests. There is no FDA-approved/cleared diagnostic for broad microbial detection. Polymerase chain reaction (PCR)/electrospray ionization-mass spectrometry (PCR/ESI-MS), commercialized as the IRIDICA system (Abbott) and formerly PLEX-ID, had been under development for over a decade and had become CE-marked and commercially available in Europe in 2014. Capable of detecting a large number of microorganisms, it was under review at the FDA when, in April 2017, Abbott discontinued it. This turn of events represents not only the loss of a potential diagnostic tool for infectious diseases but may be a harbinger of similar situations with other emerging and expensive microbial diagnostics, especially genomic tests.

ECMM CandiReg-A ready to use platform for outbreaks and epidemiological studies

BACKGROUND

Recent outbreaks of Candida auris further exemplify that invasive Candida infections are a substantial threat to patients and healthcare systems. Even short treatment delays are associated with higher mortality rates. Epidemiological shifts towards more resistant Candida spp. require careful surveillance.

OBJECTIVES

Triggered by the emergence of C auris and by increasing antifungal resistance rates the European Confederation of Medical Mycology developed an international Candida Registry (FungiScope™ CandiReg) to allow contemporary multinational surveillance.

METHODS

CandiReg serves as platform for international cooperation to enhance research regarding invasive Candida infections. CandiReg uses the General Data Protection Regulation compliant data platform ClinicalSurveys.net that holds the electronic case report forms (eCRF). Data entry is supported via an interactive macro created by the software that can be accessed via any Internet browser.

RESULTS

CandiReg provides an eCRF for invasive Candida infections that can be used for a variety of studies from cohort studies on attributable mortality to evaluations of guideline adherence, offering to the investigators of the 28 ECMM member countries the opportunity to document their cases of invasive Candida infection. CandiReg allows the monitoring of epidemiology of invasive Candida infections, including monitoring of multinational outbreaks. Here, we describe the structure and management of the CandiReg platform.

CONCLUSION

CandiReg supports the collection of clinical information and isolates to improve the knowledge on epidemiology and eventually to improve management of invasive Candida infections. CandiReg promotes international collaboration, improving the availability and quality of evidence on invasive Candida infection and contributes to improved patient management.

Estimated burden of fungal infections in Sweden

The aim of this study was to estimate the annual burden of fungal infections in Sweden using data mainly from 2016. Data on specific populations were obtained from Swedish national data registries. Annual incidence and prevalence of fungal disease was calculated based on epidemiological studies. Data on infections due to Cryptococcus sp., Mucorales, Histoplasma capsulatum, Coccidioides immitis and Pneumocystis jirovecii were retrieved from Karolinska University Laboratory and covers only 25% of Swedish population. In 2016, the population of Sweden was 9 995 153 (49.8% female). The overall burden of fungal infections was 1 713 385 (17 142/100 000). Superficial fungal infections affect 1 429 307 people (1429/100 000) based on Global Burden of Disease 14.3% prevalence. Total serious fungal infection burden was 284 174 (2843/100 000) in 2016. Recurrent Candida vulvovaginitis is common; assuming a 6% prevalence in women. Prevalence of allergic bronchopulmonary aspergillosis and severe asthma with fungal sensitisation were estimated to be 20 095 and 26 387, respectively. Similarly, chronic pulmonary aspergillosis was estimated to affect 490 patients after tuberculosis, sarcoidosis and other conditions. Candidemia incidence was estimated to be 500 in 2016 (4.7/100 000) and invasive aspergillosis 295 (3.0/100 000). In Stockholm area, Mucorales were reported in three patients in 2015, while Cryptococcus spp. were reported in two patients. In 2016, there were 297 patients PCR positive for P jirovecii. The present study shows that the overall burden of fungal infections in Sweden is high and affects 17% of the population. The morbidity, mortality and the healthcare-related costs due to fungal infections warrant further studies.

Clinical implementation of molecular methods in detection of microorganisms from blood with a special focus on PCR electrospray ionization mass spectrometry

INTRODUCTION

The ongoing improvement and development of state-of-the-art diagnostic methods indicate that we are in an era of revolution in clinical microbiological diagnosis of infectious diseases. Non-culture-based methods have the possibility to play a central role in delivering personalized microbiological diagnoses of severe infections. The PCR electrospray ionization mass spectrometry (PCR/ESI-MS) system is built on the principle of universal detection and specific identification. The performance studies using PCR/ESI-MS on whole blood samples, as well as our experiences, indicate that this method provides useful clinical information. These types of modern molecular methods deserve further development for broad implementation into clinical practices. Areas covered: The review describes briefly hitherto developed molecular assays in detection of microorganisms directly from whole blood and focuses on the clinical implementation of PCR/ESI-MS. Expert opinion: The detection of an extensive broad-spectrum of microorganisms directly from whole blood samples with a series of tests that are run automatically with a turn-around time of 8 h would be a desirable diagnostic tool for the clinical microbiology laboratories. We believe that the clinical experience with PCR-ESI MS may guide the development and establishment of similar state-of-the-art diagnostic technologies in medicine in the future.

PCR with electrospray ionization-mass spectrometry on bronchoalveolar lavage for detection of invasive mold infections in hematological patients

Invasive mold infections are life-threatening complications in patients with hematological malignancies. Conventional microbiological methods for diagnosing invasive pulmonary mold infections have low sensitivity, and molecular methods are being developed. Detection of molds using PCR with a narrow spectrum has been reported, but data with broad-spectrum PCR are lacking. In this study, the diagnostic performance and utility of a broad-spectrum PCR (broad-spectrum PCR with subsequent electrospray ionization-mass spectrometry, PCR/ESI-MS) for detection of molds in bronchoalveolar lavage (BAL) in 27 hematological patients with a new pulmonary infiltrate was analyzed. Using the revised EORTC/MSG criteria, PCR/ESI-MS was the only positive microbiological test in patients with proven invasive mold infection (n = 2) and correctly identified all cases of probable invasive pulmonary aspergillosis (n = 5). In patients with a possible invasive mold infection (n = 5), PCR/ESI-MS was positive in three patients. Mucorales was identified with PCR/ESI-MS in four patients that were all culture negative. The PCR/ESI-MS results had a clinical impact on antifungal therapy in 12 (44%) of the patients: modification of treatment in 6 (22%) patients and discontinuation in 6 (22%) patients. This study provides proof of concept that routine use of a broad-spectrum PCR for molds in bronchoalveolar lavage in immunocompromised patients is sensitive, fast, and has an impact on clinical decision-making.

Infective endocarditis due to Streptococcus dysgalactiae: clinical presentation and microbiological features

Knowledge of infective endocarditis (IE) caused by Streptococcus dysgalactiae (SD) is limited. This study aimed to identify the clinical and microbiological features of SD-caused IE and to investigate any possible synergy between penicillin and gentamicin on SD isolates. Cases of IE 2008-2016 due to SD reported to the Swedish Registry of Infective Endocarditis (SRIE) were identified. Isolates were emm typed and synergy between antibiotics was determined in time-kill experiments. Medical records were reviewed and SD-cases were compared to cases of IE due to other pathogens reported to the SRIE. Fifty cases of SD-caused IE were confirmed. emm types stC74a, stG62647, and stG643 were most commonly encountered. The patients had a median age of 74 years (range 38-93) and were significantly older compared to patients with Staphylococcus aureus-caused IE, (65 years (p = 0.003)). The median time to diagnosis from symptom onset was 1 day for patients with SD-caused IE which was less compared to patients with IE due to the other pathogens (2-15 days). Embolization was seen in 46% and the in-hospital mortality was 8%. Etest-based methods did not indicate any synergy between penicillin and gentamicin whereas synergy was noted for four out of nine isolates applying time-kill assays. This is the largest study of SD-caused IE, a condition with an acute onset predominantly affecting elderly people. Synergy between penicillin and gentamicin against some SD isolates was distinguished but the potential benefit of this must be weighed against the risk of aminoglycoside side effects.

Epidemiology of fungaemia in Sweden: A nationwide retrospective observational survey

OBJECTIVES

To identify the epidemiology and antifungal susceptibilities of Candida spp. among blood culture isolates to identify the epidemiology and antifungal susceptibilities of Candida spp. among blood culture isolates in Sweden.

METHODS

The study was a retrospective, observational nationwide laboratory-based surveillance for fungaemia and fungal meningitis and was conducted from September 2015 to August 2016.

RESULTS

In total, 488 Candida blood culture isolates were obtained from 471 patients (58% males). Compared to our previous study, the incidence of candidaemia has increased from 4.2/100 000 (2005-2006) to 4.7/100 000 population/year (2015-2016). The three most common Candida spp. isolated from blood cultures were Candida albicans (54.7%), Candida glabrata (19.7%) and species in the Candida parapsilosis complex (9.4%). Candida resistance to fluconazole was 2% in C. albicans and between 0% and 100%, in non-albicans species other than C. glabrata and C. krusei. Resistance to voriconazole was rare, except for C. glabrata, C. krusei and C. tropicalis. Resistance to anidulafungin was 3.8% while no Candida isolate was resistant to amphotericin B.

CONCLUSIONS

We report an overall increase in candidaemia but a minor decrease of C. albicans while C. glabrata and C. parapsilosis remain constant over this 10-year period.

Seven years of clinical experience with the Yeast Traffic Light PNA FISH: Assay performance and possible implications on antifungal therapy

We evaluated the performance of Yeast Traffic Light PNA FISH (YTL PNA FISH) in identification of Candida spp. from blood cultures. A total of 200 new episodes of candidaemia were analysed prospectively. The YTL PNA FISH results were reported to the clinicians and data on antifungal therapy were documented. In total, there were 164/200 (82%) positive blood culture bottles with monomicrobial growth. Coverage of monomicrobial yeast was 150/164 (91.5%). YTL PNA FISH could identify 23/24 (95.8%) Candida spp. in bottles with concomitant growth of bacteria and one yeast. Growth of two or more different yeast was observed in 12/200 (6%) blood culture bottles and the method could identify all yeast in 8/12 (66.7%). Data on antifungal treatment were available for 181/200 patients (90.5%). In 132/137 (96.4%) samples from patients without antifungal treatment, YTL PNA FISH could identify the Candida spp. or gave a negative result for yeast not included in panel, and based on the result guide appropriate antifungal therapy the same day when the blood culture bottle signalled positive. This study shows that YTL PNA FISH is a rapid, reliable diagnostic method which significantly reduces time delay for choice of appropriate antifungal therapy for critically ill patients.

Individualized Approaches Are Needed for Optimized Blood Cultures

Many strategies and technologies are available to improve blood culture (BC)-based diagnostics. The ideal approach to BCs varies between healthcare institutions. Institutions need to examine clinical needs and practices in order to optimize BC-based diagnostics for their site. Before laboratories consider offering rapid matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) or expensive rapid panel-based molecular BC diagnostics, they should optimize preanalytical, analytical, and postanalytical processes and procedures surrounding BC systems. Several factors need to be considered, including local resistance rates, antibiotic prescribing patterns, patient- and provider-types, laboratory staffing, and personnel available to liaise with clinicians to optimize antibiotic use. While there is much excitement surrounding new high-technology diagnostics, cost-neutral benefits can be realized by optimizing existing strategies and using available tools in creative ways. Rapid BC diagnostics should be implemented in a manner that optimizes impact. Strategies to optimize these BC diagnostics in individual laboratories are presented here.

The IRIDICA PCR/Electrospray Ionization-Mass Spectrometry Assay on Bronchoalveolar Lavage for Bacterial Etiology in Mechanically Ventilated Patients with Suspected Pneumonia

We studied the diagnostic performance of the IRIDICA PCR/electrospray ionization–mass spectrometry (PCR/ESI-MS) assay applied on bronchoalveolar lavage (BAL) samples, from 51 mechanically ventilated patients with suspected pneumonia, in a prospective study. In 32 patients with X-ray verified pneumonia, PCR/ESI-MS was positive in 66% and BAL culture was positive in 38% (p = 0.045), and either of the methods was positive in 69%. The following BAL result combinations were noted: PCR/ESI-MS+/culture+, 34%; PCR/ESI-MS+/culture-, 31%; PCR/ESI-MS-/culture+, 3.1%; PCR/ESI-MS-/culture-, 31%; kappa 0.36 (95% confidence interval (CI), 0.10–0.63). In pneumonia patients without prior antibiotic treatment, optimal agreement was noted with 88% PCR/ESI-MS+/culture+ and 12% PCR/ESI-MS-/culture- (kappa 1.0). However, in patients with prior antibiotic treatment, the test agreement was poor (kappa 0.16; 95% CI, -0.10–0.44), as 10 patients were PCR/ESI-MS+/culture-. In 8/10 patients the pathogens detected by PCR/ESI-MS could be detected by other conventional tests or PCR tests on BAL. Compared with BAL culture, PCR/ESI-MS showed specificities and negative predictive values of ≥87% for all individual pathogens, an overall sensitivity of 77% and positive predictive value (PPV) of 42%. When other conventional tests and PCR tests were added to the reference standard, the overall PPV increased to 87%. The PCR/ESI-MS semi-quantitative level tended to be higher for PCR/ESI-MS positive cases with pneumonia compared with cases without pneumonia (p = 0.074). In conclusion, PCR/ESI-MS applied on BAL showed a promising performance and has potential to be clinically useful in mechanically ventilated patients with suspected pneumonia. The usefulness of the method for establishment of pneumonia etiology and selection of antibiotic therapy should be further studied.

Rapid identification of Streptococcus pneumoniae in blood cultures by using the ImmuLex, Slidex and Wellcogen latex agglutination tests and the BinaxNOW antigen test

Rapid identification of Streptococcus pneumoniae in blood culture (BC) bottles is important for early directed antimicrobial therapy in pneumococcal bacteraemia. We evaluated a new latex agglutination (LA) test on BC bottles, the ImmuLex™ S. pneumoniae Omni (Statens Serum Institut, Denmark), and compared the performance with the Slidex® pneumo-Kit (bioMérieux, France) and the Wellcogen™ S. pneumoniae (Remel, UK) LA tests, as well as the BinaxNOW® S. pneumoniae (Alere, USA) antigen test. The four tests were directly applied on 358 positive BC bottles with Gram-positive cocci in pairs or chains and on 15 negative bottles. Valid test results were recorded in all cases for ImmuLex and BinaxNOW and in 88.5 % (330/373) and 94.1 % (351/373) of cases for Slidex and Wellcogen, respectively. Based on bottles positive for S. pneumoniae by conventional methods, the sensitivity of ImmuLex was 99.6 %, similar to the other tests (range, 99.6-100 %). Based on bottles positive for non-pneumococcal pathogens, the specificity of ImmuLex was 82.6 %, in comparison to 97.6 % for Slidex (p < 0.01) and 85.4 % for Wellcogen (p = ns). The BinaxNOW test had a lower specificity (64.1 %) than any LA test (p < 0.01). On BC bottles positive for α-haemolytic streptococci, ImmuLex was positive in 12/67 (17.9 %) cases, Slidex in 2/59 (3.4 %) cases, Wellcogen in 11/64 (17.2 %) cases and BinaxNOW in 25/67 (37.3 %) cases. In conclusion, the ImmuLex test provides a valid and sensitive technique for the rapid detection of S. pneumoniae in BC bottles, similar to the other compared methods. However, the specificity was sub-optimal, since the test may cross-react with other Gram-positive bacteria.

Microbiological diagnosis of Eggerthella lenta blood culture isolates in a Swedish tertiary hospital: Rapid identification and antimicrobial susceptibility profile

Eggerthella lenta is a Gram-positive anaerobic bacillus. Improved diagnostics and increased awareness of rare pathogens have revealed its potential to cause serious invasive infections. In this study, 18 clinical E. lenta isolates derived from positive blood cultures were included. Underlying problems of the patients were in the majority of cases related to the gastrointestinal tract. The performance of two MALDI-TOF MS systems, i.e. Bruker and Vitek MS, in identification of E. lenta was analyzed. In addition, the minimal inhibitory concentrations for clinically relevant antimicrobial agents were determined by routine procedures using E-test. 17 of the 18 E. lenta isolates investigated in this study were correctly identified to species level by the Bruker MS system, while the Vitek MS system identified all 18 isolates. Antimicrobial sensitivity towards the tested agents was in general good. However, high resistance rates were observed for penicillin G and piperacillin-tazobactam based on EUCAST breakpoints.

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.

Rapid identification of bacteria from positive blood culture bottles by MALDI-TOF MS following short-term incubation on solid media

Rapid identification of bacteria from blood cultures enables early initiation of appropriate antibiotic treatment in patients with bloodstream infections (BSI). The objective of the present study was to evaluate the use of matrix-associated laser desorption ionization-time of flight (MALDI-TOF) MS after a short incubation on solid media for rapid identification of bacteria from positive blood culture bottles. MALDI-TOF MS was performed after 2.5 and 5.5 h plate incubation of samples from positive blood cultures. Identification scores with values ≥ 1.7 were accepted as successful identification if the results were confirmed by conventional methods. Conventional methods included MALDI-TOF MS, Vitek 2, and diverse biochemical and agglutination tests after overnight culture. In total, 515 positive blood cultures with monomicrobial bacterial growth representing one blood culture per patient were included in the study. There were 229/515 (44.5%) and 286/515 (55.5%) blood culture bottles with Gram-negative bacteria (GNB) and Gram-positive bacteria (GPB), respectively. MALDI-TOF MS following short-term culture could accurately identify 300/515 (58.3%) isolates at 2.5 h, GNB being identified in greater proportion (180/229; 78.6%) than GPB (120/286; 42.0%). In an additional 124/515 bottles (24.1%), identification was successful at 5.5 h, leading to accurate identification of bacteria from 424/515 (82.3%) blood cultures after short-term culture. Interestingly, 11/24 of the isolated anaerobic bacteria could be identified after 5.5 h. The present study demonstrates, in a large number of clinical samples, that MALDI-TOF MS following short-term culture on solid medium is a reliable and rapid method for identification of bacteria from blood culture bottles with monomicrobial bacterial growth.

The origin of endodontic Enterococcus faecalis explored by comparison of virulence factor patterns and antibiotic resistance to that of isolates from stool samples, blood cultures and food

AIM

To elucidate the origin of Enterococcus faecalis isolated from secondary root canal infections and the possibility for a foodborne transmission by comparing them to strains recovered from food, blood and stool regarding putative virulence factors and antibiotic susceptibility profiles, where strains from common origin were hypothesized to harbour similar characteristics.

METHODOLOGY

A total of 108 E. faecalis strains recovered in the county of Stockholm, Sweden, were screened using PCR for putative virulence factors esp, cylA, gelE/gelatinase-negative phenotype (ef1841/fsrC), efaA, ace and asa1. The minimum inhibitory concentration (MIC) for ampicillin, piperacillin-tazobactam, imipenem, gentamicin, vancomycin, ciprofloxacin and linezolid was determined using the agar dilution method.

RESULTS

Next to strains from blood, the food isolates presented the highest average number of virulence determinants and were frequently enriched with asa1 coding for aggregation substance. None of the endodontic strains carried cylA, and the gelatinase-negative phenotype caused by a deletion dominated the group. Altogether, the most prevalent genes were gelE, efaA and ace, and a combination of them was equally present in approximately 80% of the strains from food, stool and root canals in comparison with 43.3% of the blood isolates. High-level resistance to ciprofloxacin and gentamicin was observed in 30% of the blood isolates, whereas the isolates from other origins, with single exceptions, were susceptible to all tested antibiotics.

CONCLUSIONS

Evidence for a foodborne transmission, explaining the high reported prevalence of E. faecalis in root filled teeth, could not be determined based on the similarities in virulence factor patterns and antibiotic susceptibility. The only linkage between isolates from food and root canals consisted of a shared common combination of the genes gelE, efaA and ace. The high occurrence of putative virulence traits in food isolates questions the safety of E. faecalis in food products.

The Uni-Gold™ Streptococcus pneumoniae urinary antigen test: an interassay comparison with the BinaxNOW® Streptococcus pneumoniae test on consecutive urine samples and evaluation on patients with bacteremia

The performance of the recently commercialized Uni-Gold™ Streptococcus pneumoniae test for the detection of pneumococcal antigen in urine was studied in a multicenter study. First, we studied the interassay agreement between Uni-Gold™ and the BinaxNOW® S. pneumoniae urinary antigen test on 337 consecutive urine samples sent to the laboratory for the detection of pneumococcal antigen. The two tests performed similarly (κ = 0.82): both tests positive in 27 cases, both tests negative in 299 cases, and with divergent test results in 11 cases. Secondly, the tests were run on urine samples from 203 patients with bacteremia, including 51 patients with pneumococcal bacteremia. The sensitivities and specificities were 67 and 86 % for Uni-Gold™, and 57 % and 94 % for BinaxNOW®, respectively. The false-positivity rate was significantly higher for Uni-Gold™ compared with BinaxNOW® in patients with Escherichia coli bacteremia (15 vs. 2.1 %, p = 0.04), and tended to be higher in patients with bacteremia with alpha-hemolytic streptococci (32 vs. 11 %, p = 0.13). When cases with E. coli and alpha-hemolytic streptococci were excluded from the analysis, the overall false-positivity rate was 9/85 (11 %) for Uni-Gold™ and 6/85 (7.1 %) for BinaxNOW®. In conclusion, the study showed that Uni-Gold™ was not inferior to BinaxNOW® for the detection of pneumococcal urinary antigen in patients with pneumococcal bacteremia. The specificity of Uni-Gold™ was suboptimal due to false-positive results in cases with E. coli and alpha-hemolytic streptococci bacteremia. However, in patient populations usually subjected to testing for pneumococcal urinary antigen, such as pneumonia and meningitis patients, bacteremia with these pathogens is uncommon. The diagnostic usefulness of the Uni-Gold™ test should be further evaluated.

A multicentre hospital outbreak in Sweden caused by introduction of a vanB2 transposon into a stably maintained pRUM-plasmid in an Enterococcus faecium ST192 clone

The clonal dissemination of VanB-type vancomycin-resistant Enterococcus faecium (VREfm) strains in three Swedish hospitals between 2007 and 2011 prompted further analysis to reveal the possible origin and molecular characteristics of the outbreak strain. A representative subset of VREfm isolates (n = 18) and vancomycin-susceptible E. faecium (VSEfm, n = 2) reflecting the spread in time and location was approached by an array of methods including: selective whole genome sequencing (WGS; n = 3), multi locus sequence typing (MLST), antimicrobial susceptibility testing, virulence gene profiling, identification of mobile genetic elements conferring glycopeptide resistance and their ability to support glycopeptide resistance transfer. In addition, a single VREfm strain with an unrelated PFGE pattern collected prior to the outbreak was examined by WGS. MLST revealed a predominance of ST192, belonging to a hospital adapted high-risk lineage harbouring several known virulence determinants (n≥10). The VREfm outbreak strain was resistant to ampicillin, gentamicin, ciprofloxacin and vancomycin, and susceptible to teicoplanin. Consistently, a vanB2-subtype as part of Tn1549/Tn5382 with a unique genetic signature was identified in the VREfm outbreak strains. Moreover, Southern blot hybridisation analyses of PFGE separated S1 nuclease-restricted total DNAs and filter mating experiments showed that vanB2-Tn1549/Tn5382 was located in a 70-kb sized rep17/pRUM plasmid readily transferable between E. faecium. This plasmid contained an axe-txe toxin-antitoxin module associated with stable maintenance. The two clonally related VSEfm harboured a 40 kb rep17/pRUM plasmid absent of the 30 kb vanB2-Tn1549/Tn5382 gene complex. Otherwise, these two isolates were similar to the VREfm outbreak strain in virulence- and resistance profile. In conclusion, our observations support that the origin of the multicentre outbreak was caused by an introduction of vanB2-Tn1549/Tn5382 into a rep17/pRUM plasmid harboured in a pre-existing high-risk E. faecium ST192 clone. The subsequent dissemination of VREfm to other centres was primarily caused by clonal spread rather than plasmid transfer to pre-existing high-risk clones.

Transport time for blood culture bottles: underlying factors and its consequences

In the present study we investigated transport times for blood cultures from three tertiary-care hospitals to Karolinska University Laboratory and identified predictors of long transport times. Concomitantly, consequences of delayed incubation on total detection time (TDT) were analyzed by in vitro sepsis models. A total of 909 blood cultures were studied. The median (interquartile range) transport time was 9 (3-15) h. The hospital accommodating the microbiology laboratory had the shortest transport time compared to the other two hospitals (P < 0.0001). Samples taken between 16:00-24:00 had longer transport times compared to samples taken between 8:00-16:00 and 24:00-08:00 (P < 0.0001). In vitro experiments showed that TDT was longer for samples pre-incubated at room temperature (RT) for 19 h compared to the ones pre-incubated for 2 h or 9.5 h (P < 0.0001). In conclusion, off-site location, time of sampling and number of transports per day were related to, and predictors of transport time.

A short-term dietary supplementation with high doses of vitamin E increases NK cell cytolytic activity in advanced colorectal cancer patients

Cancer patients with advanced disease display signs of immune suppression, which constitute a major obstacle for effective immunotherapy. Both T cells and NK cells are affected by a multitude of mechanisms of which the generation of reactive oxygen species is of major importance. Therefore, we hypothesized that two weeks of high-dose treatment with the anti-oxidant vitamin E may enhance NK cell function in cancer patients by protecting from oxidative stress. Seven patients with colorectal cancer (Dukes stage C and D) received a daily dose of 750 mg of vitamin E during a period of two weeks and the function, phenotype and receptor expression of NK cells were analyzed. The short-term vitamin E treatment significantly improved NK cell cytolytic activity in six out of the seven patients analyzed. The increased NK cell activity in patients' PBMC was not due to increased numbers of NK cells or an increase in the proportion of the CD56(dim) NK cell subpopulation. Furthermore, neither an increased perforin expression nor an enhanced ability of NK cells to produce IFN-gamma was observed as a result of vitamin E treatment. Finally, vitamin E treatment was associated with a minor, but consistent, induction of NKG2D expression in all patients analyzed. In conclusion, this pilot study demonstrates that vitamin E may boost NK cell function in patients with colorectal cancer. Further studies are warranted to explore the potential of vitamin E as an adjuvant for immunotherapy against cancer and to determine the underlying mechanism(s) behind vitamin E induced NK cell activation.