Antimicrobial susceptibility testing of anaerobic bacteria causing bacteremia: A 13-year (2010-2022) retrospective study in a tertiary hospital.

Infections from anaerobic microorganisms result from breached mucosal barriers, posing a significant mortality risk. A retrospective study at Hospital Universitario La Paz (Madrid) from 2010 to 2022 analyzed 491 (6.17 %) anaerobic bacteremia cases out of 7956 significant bacteremia cases among 171,833 blood culture requests. Bacteroides fragilis was the most frequently isolated species (28.3 %), followed by Clostridium perfringens (13.6 %). B. fragilis showed good susceptibility to amoxicillin/ clavulanic acid (86 %), piperacillin/tazobactam (86 %), and metronidazole (87.7 %). In general, non-fragilis Bacteroides species showed low susceptibility to penicillin (7 %), amoxicillin (17.5 %), and clindamycin (64.9 %). Of our 13 non-perfringens Clostridium isolates, four exhibited resistance to penicillin and four showed resistance to clindamycin. Lactobacillus species were highly susceptible to antibiotics tested. Prevotella spp. showed low susceptibility to penicillin (20 %), amoxicillin (20 %), and clindamycin (40 %). The study contributes valuable data for monitoring and improving anaerobic bacteremia treatment.

A New Application of MALDI Biotyper for a Potential Use in Therapeutic Drug Monitoring of Voriconazole.

We present a proof-of-concept study on the use of MALDI Biotyper to detect and monitor the levels of voriconazole in human serum. A simple extraction-concentration method and a MALDI Biotyper protocol were developed, and a parent ion of voriconazole (1 H+) could be detected and quantified with good reproducibility. Our results point to a new application of MALDI Biotyper for therapeutic drug monitoring.

Epidemiology of bloodstream Candida species in a Spanish tertiary care hospital as a guide for implementation of T2MR (T2CANDIDA®) for rapid diagnosis of candidemia.

The aim of this work was to study the epidemiology of candidemia in our hospital in order to determine whether the T2MR system might be a useful tool for early diagnosis of candidemia in selected units. We perform a retrospective review of all candidemia episodes registered in the last 12 years in selected units of our hospital in adult and pediatric patients. Candida species and antifungal susceptibility patterns were registered. A total of 686 isolates were registered, of which 625 were infections due to the five most common species of Candida. C. albicans (45.6%) and C. parapsilosis (33.1%) were the predominant species found in our institution. In adults these species were closely followed by C. glabrata (12-21%) in all units. While in pediatric medical and intensive care units (PICU), these species were followed by other uncommon yeasts. Resistance rates to triazoles were low in C. albicans and C. parapsilosis. In C. glabrata and C. tropicalis the resistance rates to fluconazole ranged from 10.86 to 6.67%. Resistance rates for echinocandins were very low and all strains were susceptible to amphotericin B. T2Candida® might be useful to guide antifungal targeted treatment and discontinuation of antifungal empirical treatment in those units where the five most common Candida species represent more than the ninety percent of the isolates. The selection of medical and surgical units should be based on local epidemiology and antifungal susceptibility patterns. Incidence should be taken into account in order to make clinical decisions based on negative results. LAY ABSTRACT: T2Candida® might be useful selectively in clinical units according to their local epidemiology, antifungal resistance patterns, and incidence of candidemia. It optimizes the clinical value of positive results supporting decisions about targeted therapies or discontinuations based on negative results.

Severity of bronchiolitis in infants is associated with their parents' tobacco habit.

The aim of this study was to investigate the effect of tobacco smoke exposure among severely pediatric ICU patients. A prospective epidemiological observational study was conducted among children with bronchiolitis younger than 2 years of age admitted to the Pediatric Intensive Care Unit of Children's University Hospital La Paz during the October 2017 to March 2018 outbreak. On admission, parents were asked whether they smoked. In children who required invasive mechanical ventilation, endotracheal aspirate was collected at the time of intubation. A total of 102 patients with bronchiolitis were studied. Among these, 14 (47%) of 30 infants whose parents smoked required invasive mechanical ventilation vs. 14 (19%) of 72 whose parents were nonsmokers (p = 0.007). Among patients on invasive mechanical ventilation, 10 (71%) of 14 infants with secondhand smoke exposure presented pulmonary bacterial superinfection vs. 3 (21%) of 14 in the unexposed (p = 0.012).Conclusion: Secondhand smoke exposure is an additional high risk for pulmonary bacterial superinfection and invasive mechanical ventilation in infants with severe acute bronchiolitis What is known: •Environmental tobacco smoke exposure is known to be an important risk factor for childhood lower respiratory tract infections. •Tobacco smoke makes structural changes in the respiratory tract and reduces the immune response. What in new: •Secondhand smoke exposure showed to be associated with the increased need and duration of invasive mechanical ventilation, and pediatric intensive care length of stay. •Tobacco smoke exposure is an additional risk factor for the presence of bacteria in the endotracheal aspirate.

Candidemia Diagnosis With T2 Nuclear Magnetic Resonance in a PICU: A New Approach.

OBJECTIVES: Early diagnosis of invasive Candida infections is a challenge for pediatricians, intensivists, and microbiologists. To fill this gap, a new nanodiagnostic method has been developed using manual application of T2 nuclear magnetic resonance to detect Candida species. The aim of this study was to evaluate, prospectively, the usefulness as a tool diagnosis of the T2Candida panel in pediatric patients admitted at the PICU compared with blood culture. DESIGN: This is a prospective, observational, and unicentric study to compare T2Candida results with simultaneous blood cultures for candidemia diagnose. SETTING: This study was carried out in a 1,300-bed tertiary care hospital with a 16-bed medical-surgical PICU. PATIENTS: Sixty-three patients from 0 to 17 years old were enrolled in this study, including those undergoing solid organ transplantation (kidney, liver, pulmonary, multivisceral, intestinal, and heart) and hematopoietic stem cell transplantation. MEASUREMENTS AND MAIN RESULTS: Seven patients were positive by the T2Candida test. Only two of them had the simultaneous positive blood culture. T2Candida yielded more positive results than blood cultures. CONCLUSIONS: T2Candida might be useful for the diagnosis of candidemia in PICUs. The prevalence of candidemia might be underestimated in this pediatric population. The use of this diagnostic tool in these units may help clinicians to start adequate and timely antifungal treatments.

The challenge of molecular diagnosis of bloodstream infections.

Early detection and identification of pathogens in bloodstream infections (BSI) is important to initiate or adjust antibiotic therapy as soon as possible. The current gold standard for diagnostic of BSI infection is the blood culture, that has a turnaround time of one to few days. Molecular tests performed directly in blood samples have promised faster diagnostics, with response times of a few hours, but their implementation into the clinical routine has been hampered by critical technical and procedural problems. Assay integration into laboratory workflows with random-access loading mode and minimal hands-on time is essential to meet rapid response times. Decreasing assay costs will favor fair clinical evaluations and might increase the applicability of the assays. Control of background contamination with bacterial DNA is one of the most difficult problems and might be avoided with pathogen-specific real-time PCR designs oriented to particular patient groups, or perhaps by quantitative, next-generation sequencing approaches.

Isolation of Rhodotorula mucilaginosa from blood cultures in a tertiary care hospital.

Rhodotorula species have traditionally been considered as one of common non-virulent environmental inhabitant. They have emerged as an opportunistic pathogen, particularly in immunocompromised hosts and most infections have been associated with intravenous catheters in these patients. We review the isolates in blood cultures of Rhodotorula mucilaginosa in our Hospital. We describe the demographic and clinical features of the cases and the antifungal susceptibility profiles of the isolates. Selected patients had an isolation of R. mucilaginosa in blood cultures in our tertiary care Hospital. All data were collected retrospectively from clinical records during 5 years. We report 8 isolates in blood, two of them were considered contaminants. Immunosuppression, surgery, previous antibiotic therapy were common clinical features. For all the isolates, minimum inhibitory concentration (MIC) values were high for echinocandins and azoles and low for amphotericin B and 5-flucytosine. One strain showed atypical susceptibility profile. Rhodotorula mucilaginosa may be present on the skin and blood cultures can be contaminated. Fungaemia due to R. mucilaginosa is a rare clinical entity which requires risk factors but clinically relevant because of the multiresistant profile. Rhodotorula mucilaginosa shows high MIC values for azoles and echinocandins, therefore amphotericin B and flucytosine must be administered as antifungal therapy.

Galactomannan enzyme immunoassay and quantitative Real Time PCR as tools to evaluate the exposure and response in a rat model of aspergillosis after posaconazole prophylaxis.

INTRODUCTION: A steroid-immunosuppressed rat model of invasive pulmonary aspergillosis was use to examine the usefulness of galactomannan enzyme immunoassay (GM) and quantitative real time PCR (RT-PCR) in evaluating the association between response and exposure after a high dose of prophylactic posaconazole. METHODS: Two different strains of Aspergillus fumigatus with different in vitro posaconazole susceptibility were used. RESULTS: Serum concentrations demonstrated similar posaconazole exposure for all treated animals. However, response to posaconazole relied on the in vitro susceptibility of the infecting strain. After prophylaxis, galactomannan index and fungal burden only decreased in those animals infected with the most susceptible strain. CONCLUSION: This study demonstrated that both biomarkers may be useful tools for predicting efficacy of antifungal compounds in prophylaxis.

Evaluation of cytomegalovirus infection in low-birth weight children by breast milk using a real-time polymerase chain reaction assay.

Human Cytomegalovirus (CMV) is the most common cause of intrauterine and perinatal infections worldwide. Postnatal CMV transmission has usually no consequences, but in some cases it may produce disease in preterm infants. Literature reports a broad range of breast milk-acquired CMV infections (5.7-58.6%), which depends on the study's design and the treatment of the milk. To evaluate CMV transmission via breast milk, a prospective study using a real-time PCR assay was performed. One hundred and thirty-one mothers (accounting for 160 children) accepted the participation in the study. Urine samples from the infants and breast milk samples from their mothers were collected at 3, 15, 30, 60, and 90 days after delivery. CMV-DNA in breast milk was analysed by quantitative real-time PCR assay Affigene® CMV Trender (Cepheid, Bromma, Sweden). The breast milk samples from 92 mothers (92 of 131, 70.2%) were positive for CMV by PCR. CMV infection was detected in thirteen children by PCR, and four of them (30.7%) had clinical symptoms. There were not significant differences in morbidity between symptomatic and non- symptomatic patients; nonetheless, the average length of hospitalization in symptomatic children was higher than that of non-symptomatic children (P < 0.05). The rtPCR technique is useful for detection of mothers with high viral loads of CMV-DNA in milk, and might be of help to decide whether to freeze the breast milk in preterm children less than 28 weeks.

Epidemiological changes in invasive Streptococcus pyogenes infection during the UK alert period: A molecular comparative analysis from a tertiary Spanish hospital in 2023.

OBJECTIVES: To study the genomic epidemiology of Streptococcus pyogenes causing bloodstream infections (GAS-BSI) in a Spanish tertiary hospital during the United Kingdom invasive S. pyogenes outbreak alert. METHODS: Retrospective epidemiological analysis of GAS-BSI during the January-May 2017-2023 period. WGS was performed using Ion torrent GeneStudio™ S5 system for emm typing and identification of superantigen genes in S. pyogenes isolated during the 2022-2023 UK outbreak alert. RESULTS: During 2023, there were more cases of GAS-BSI compared to the same period of previous year with a non-significant increase in children. Fourteen isolates were sequenced. The emm1 (6/14, 42.9%) and emm12 (2/14, 14.3%) types predominated; 5 of 6 (75%) emm1 isolates were from the M1UK clone. The most detected superantigen genes were speG (12/14, 85.7%), speC (10/14, 71.4%), speJ (7/14, 50%), and speA (5/15, 33.3%). speA and speJ were predominant in M1UK clone. CONCLUSIONS: Our genomic epidemiology in 2023 is similar to the reported data from the UK outbreak alert in the same period and different from previous national S. pyogenes surveillance reports.

Determination of voriconazole serum concentration by bioassay, a valid method for therapeutic drug monitoring for clinical laboratories.

We describe here a simple, fast, and reliable bioassay method for therapeutic drug monitoring of voriconazole. Fifty-eight clinical and external quality control samples were evaluated with this microbiological assay, and results were compared with those obtained with a previously validated chromatographic method. A good correlation between both assays was observed. This particular microbiological method was demonstrated to be simple and offers enough precision and accuracy to perform voriconazole therapeutic drug monitoring in laboratories without specialized equipment.

Development and validation of a fast HPLC/photodiode array detection method for the measurement of voriconazole in human serum samples. A reference laboratory experience.

The aim of this study was the development and validation of a fast and simple high performance liquid chromatography method for measuring voriconazole in human serum using ravuconazole as an external standard. The experience of the reference laboratory in therapeutic drug monitoring of voriconazole is also reported. This method is based on the precipitation of proteins in human serum and detection by HPLC/UV. Chromatographic separation is achieved using an isocratic solvent delivery with detection at 255 nm and a run time of 7 min. The assay was validated according to international guidelines and was also applied to the analysis of 141 trough serum samples from patients treated with voriconazole. All validation parameters met the criteria set out in FDA guidelines for bioanalytical methods. A high interpatient and intrapatient variability was observed in clinical samples. This method is accurate enough to perform therapeutic drug monitoring in patients receiving voriconazole treatment.

Are cerebrospinal fluid biochemical parameters valid to predict positive results in microbiological molecular diagnostic platforms? A 4-year experience with the FilmArray® Panel Meningitis/Encephalitis for detection of community-acquired bacterial meningitis.

OBJECTIVE: To demonstrate whether the use of the FilmArray® Meningitis/Encephalitis panel (M/E) in the diagnosis of bacterial meningitis can be optimized based on the screening of cerebrospinal fluid biochemical parameters and whether there is a correlation between biochemical data and positive results of the technique. MATERIAL AND METHODS: We used data from La Paz University Hospital between September 5, 2017 and December 1, 2021, from patients who had had the FilmArray® panel M/E performed on cerebrospinal fluid samples. RESULTS: Bacterial meningitis was suspected in 63.9% of the patients; 38.15% had a positive result on the FilmArray® panel M/E, of which 68.97% were isolated in culture. Of the biochemical parameters studied in cerebrospinal fluid, white blood cell count, lactate, and protein were increased in PCR-positive patients, but glucose was decreased. DISCUSSION: Only lactate showed a significant contribution to the model, with a cut-off point of 4.65 mmol/L with a sensitivity of 81.5% and a specificity of 96.4%.

Staphylococcus aureus bacteremia in patients with SARS-CoV-2 infection.

Objectives: The aim was to compare the incidence of Staphylococcus aureus bacteremia in COVID-19 and non-COVID-19 adult patients during the pandemic period versus the previous two years. Also, we described the characteristics of both cohorts of patients in pandemic period to find differences. Material and methods: Retrospective study in our tertiary-care centre reviewing S. aureus bacteremia episodes in COVID-19 and non-COVID-19 patients through clinical records and the Microbiology Department database. Results: In 2018 and 2019, the incidence of S. aureus bacteremia episodes was 1.95 and 1.63 per 1000 admissions respectively. In the pandemic period, global incidence was 1.96 episodes per 1000 non-COVID-19 admissions and 10.59 episodes per 1000 COVID-19 admissions. A total of 241 bacteremia was registered during this pandemic period in 74 COVID-19 patients and in 167 non-COVID-19 patients. Methicillin resistance was detected in 32.4% and 13.8% of isolates from COVID-19 and non-COVID-19 patients respectively. In COVID-19 patients, mortality rates were significantly higher. Conclusions: We showed a significantly high rates of S. aureus bacteremia incidence in COVID-19 patients and higher methicillin resistance and 15-day mortality rates than in non-COVID-19 patients.

Objetivos: Comparar la incidencia de bacteriemias por Staphylococcus aureus en pacientes adultos COVID-19 y no-COVID-19 durante la pandemia frente a los 2 años previos. Además, describimos las características de ambas cohortes en periodo pandémico para encontrar diferencias. Material y métodos: Estudio retrospectivo en nuestro centro de tercer nivel a través de historias clínicas y la base de datos del Servicio de Microbiología. Resultados: En 2018 y 2019, la incidencia de bacteriemias fue de 1.95 y 1,63 casos por cada 1.000 ingresos respectivamente. En pandemia, la incidencia global fue de 1,96 casos por cada 1.000 ingresos no-COVID-19 y de 10,59 casos por cada 1.000 ingresos COVID-19. Durante la pandemia se registraron 241 bacteriemias en 74 pacientes COVID-19 y en 167 pacientes no-COVID-19. La resistencia a meticilina se detectó en el 32,4 y 13,8% de los aislados de pacientes COVID-19 y no-COVID-19 respectivamente. En pacientes COVID-19 la mortalidad fue significativamente mayor. Conclusiones: Mostramos una incidencia significativamente alta de bacteriemias por S. aureus en pacientes COVID-19, así como mayores tasas de resistencia a meticilina y mortalidad a los 15 días que en pacientes no-COVID-19.

Staphylococcus aureus bacteremia in patients with SARS-CoV-2 infection.

OBJECTIVES: The aim was to compare the incidence of Staphylococcus aureus bacteremia in COVID-19 and non-COVID-19 adult patients during the pandemic period versus the previous two years. Also, we described the characteristics of both cohorts of patients in pandemic period to find differences. MATERIAL AND METHODS: Retrospective study in our tertiary-care centre reviewing S. aureus bacteremia episodes in COVID-19 and non-COVID-19 patients through clinical records and the Microbiology Department database. RESULTS: In 2018 and 2019, the incidence of S. aureus bacteremia episodes was 1.95 and 1.63 per 1000 admissions respectively. In the pandemic period, global incidence was 1.96 episodes per 1000 non-COVID-19 admissions and 10.59 episodes per 1000 COVID-19 admissions. A total of 241 bacteremia was registered during this pandemic period in 74 COVID-19 patients and in 167 non-COVID-19 patients. Methicillin resistance was detected in 32.4% and 13.8% of isolates from COVID-19 and non-COVID-19 patients respectively. In COVID-19 patients, mortality rates were significantly higher. CONCLUSIONS: We showed a significantly high rates of S. aureus bacteremia incidence in COVID-19 patients and higher methicillin resistance and 15-day mortality rates than in non-COVID-19 patients.

Evaluation of MSP96, MBT Biotarget™ 96 and AnchorChip™ 600/96 MALDI-TOF MS target plates for direct identification of positive blood cultures.

The objective of the study was to compare the diagnostic performances of three Bruker MALDI-TOF MS target plates. A combination of two or three targets results in an increase of the identification percentage, especially in problem isolates as gram-positive cocci and yeast.

Rapid antigen test for adenovirus in children: Age and onset of symptoms are important.

INTRODUCTION: Respiratory infection is the most common human adenovirus (HAdV) disease accounting for 7-8% of viral respiratory diseases in children less than 5 years. Differentiation of bacterial infections and viral infections is a common clinical problem. MATERIAL AND METHODS: One hundred oropharyngeal swabs obtained from October 2019 to November 2020 from patients attending the paediatric emergency room with suspicion of upper respiratory tract infection and negative results in influenza and RSV tests were included. Oropharyngeal swabs specimens were rapidly processed with STANDARD™ F Adeno Respi Ag FIA and the results were confirmed by RealStar® Adenovirus PCR Kit 1.0 (Altona diagnostics). RESULTS: STANDARD™ F Adeno Respi Ag FIA had sensitivity and specificity values of 71.93% and 100% respectively. The performance of the test was higher in samples from children younger than 24 months and taken less than 72h since the beginning of symptoms. In this subgroup the test had 88.8% sensitivity and 100% specificity. CONCLUSION: STANDARD™ F Adeno Respi Ag FIA may improve the management of respiratory diseases in children younger than 24 months and less than 72h since the beginning of symptoms in paediatric emergency rooms.

Intestinal loads of extended-spectrum beta-lactamase and Carbapenemase genes in critically ill pediatric patients.

Introduction: Intestinal colonization by Multi-Drug Resistant Organisms (MDROs) can pose a threat on the health of critically ill patients. The extent of colonization by these organisms is related to previous antibiotic treatments and their ability to cause infections among adult patients. The aim of this study is to determine the relationship between the intestinal Relative Loads (RLs) of selected antibiotic resistance genes, antibiotic consumption and extra-intestinal spread among critically ill pediatric patients. Methods: RLs of bla CTX-M-1-Family, bla OXA-1, bla OXA-48 and bla VIM were determined in 382 rectal swabs obtained from 90 pediatric critically ill patients using qPCRs. The RLs were compared to the patients' demographics, antibiotic consumption, and detection of MDROs from extra-intestinal sites. 16SrDNA metagenomic sequencing was performed for 40 samples and clonality analyses were done for representative isolates. Results and discussion: 76 (74.45%) patients from which 340 (89.01%) rectal swabs were collected had at least one swab that was positive for one of the tested genes. Routine cultures did not identify carbapenemases in 32 (45.1%) and 78 (58.2%) swabs that were positive by PCR for bla OXA-48 and blaVIM, respectively. RLs of above 6.5% were associated with extra-intestinal spread of blaOXA-48-harboring MDROs. Consumption of carbapenems, non-carbapenem ß-lactams, and glycopeptides were statistically associated with testing negative for bla CTX-M-1-Family and bla OXA-1 while the consumption of trimethoprim/sulfamethoxazole and aminoglycosides was associated with testing negative for blaOXA-48 (P<0.05). In conclusion, targeted qPCRs can be used to determine the extent of intestinal dominance by antibiotic resistant opportunistic pathogens and their potential to cause extra-intestinal infections among a critically ill pediatric population.

Multicentre Surveillance of Candida Species from Blood Cultures during the SARS-CoV-2 Pandemic in Southern Europe (CANCoVEU Project).

Introduction: Surveillance of Candida species isolates from blood cultures (BCs) in Europe is considered fragmented, unable to allow the definition of targets of antifungal stewardship recommendations especially during the SARS-CoV-2 pandemic. Methods: We performed a multicentric retrospective study including all consecutive BC Candida isolates from six Southern European tertiary hospitals (1st January 2020 to 31st December 2021). Etiology, antifungal susceptibility patterns, and clinical setting were analyzed and compared. Results: C. albicans was the dominant species (45.1%), while C. auris was undetected. Candida species positive BC events increased significantly in COVID-19 ICUs in 2021 but decreased in other ICUs. Resistance to azole increased significantly and remained very high in C. albicans (fluconazole from 0.7% to 4.5%, p = 0.03) and C. parapsilosis complex (fluconazole up to 24.5% and voriconazole up to 8.9%), respectively. Resistance to caspofungin was remarkable in C. tropicalis (10%) and C. krusei (20%), while resistance to at least one echinocandin increased in 2021, especially in C. parapsilosis complex (from 0.8% to 5.1%, p = 0.05). Although no significant differences were observed over the study period, fluconazole and echinocandin resistance increased in COVID-19 ICUs by up to 14% and 5.8%, respectively, but remained undetected in non-intensive COVID-19 wards. Conclusions: Antifungal stewardship activities aimed at monitoring resistance to echinocandin in C. tropicalis and C. krusei, and against the spread of fluconazole resistant C. parapsilosis complex isolates are highly desirable. In COVID-19 patients, antifungal resistance was mostly present when the illness had a critical course.

Voriconazole serum levels measured by high-performance liquid chromatography: a monocentric study in treated patients.

In this study we present the results of a therapeutic drug monitoring retrospective analysis involving 14 patients with several underlying diseases who were receiving voriconazole for the treatment of fungal infections. A simple high performance liquid chromatography assay with ultraviolet detection was used in the drug monitoring. We report here that serum concentrations were highly variable and unpredictable in most patients. We also found that lack of response was more frequent in patients with levels persistently lower than 1 mg/l. The number of samples with voriconazole concentrations below 1 mg/l was significantly higher in patients who exhibited therapeutic failures (88% versus 27%; P < 0.001). In addition, the period of time in which voriconazole concentrations were maintained below 1 mg/l was slightly higher in patients in the failure group. We suggest that serum concentration should be individually quantified for patients receiving voriconazole therapy. Further prospective studies are needed to clarify the potential benefit of the individualization of treatment.