Microbiome profile and calprotectin levels as markers of risk of recurrent Clostridioides difficile infection

Introduction

Clostridioides difficile infection (CDI) is the main cause of nosocomial diarrhoea in developed countries. Recurrent CDI (R-CDI), which affects 20%-30% of patients and significantly increases hospital stay and associated costs, is a key challenge. The main objective of this study was to explore the role of the microbiome and calprotectin levels as predictive biomarkers of R-CDI.

Methods

We prospectively (2019-2021) included patients with a primary episode of CDI. Clinical data and faecal samples were collected. The microbiome was analysed by sequencing the hypervariable V4 region of the 16S rRNA gene on an Illumina Miseq platform.

Results

We enrolled 200 patients with primary CDI, of whom 54 developed R-CDI and 146 did not. We analysed 200 primary samples and found that Fusobacterium increased in abundance, while Collinsella, Senegalimassilia, Prevotella and Ruminococcus decreased in patients with recurrent versus non-recurrent disease. Elevated calprotectin levels correlated significantly with R-CDI (p=0.01). We built a risk index for R-CDI, including as prognostic factors age, sex, immunosuppression, toxin B amplification cycle, creatinine levels and faecal calprotectin levels (overall accuracy of 79%).

Discussion

Calprotectin levels and abundance of microbial genera such as Fusobacterium and Prevotella in primary episodes could be useful as early markers of R-CDI. We propose a readily available model for prediction of R-CDI that can be applied at the initial CDI episode. The use of this tool could help to better tailor treatments according to the risk of R-CDI.

Clinical presentation, microbiology, and prognostic factors of prosthetic valve endocarditis. Lessons learned from a large prospective registry

BACKGROUND

Prosthetic valve endocarditis (PVE) is a serious infection associated with high mortality that often requires surgical treatment.

METHODS

Study on clinical characteristics and prognosis of a large contemporary prospective cohort of prosthetic valve endocarditis (PVE) that included patients diagnosed between January 2008 and December 2020. Univariate and multivariate analysis of factors associated with in-hospital mortality was performed.

RESULTS

The study included 1354 cases of PVE. The median age was 71 years with an interquartile range of 62-77 years and 66.9% of the cases were male. Patients diagnosed during the first year after valve implantation (early onset) were characterized by a higher proportion of cases due to coagulase-negative staphylococci and Candida and more perivalvular complications than patients detected after the first year (late onset). In-hospital mortality of PVE in this series was 32.6%; specifically, it was 35.4% in the period 2008-2013 and 29.9% in 2014-2020 (p = 0.031). Variables associated with in-hospital mortality were: Age-adjusted Charlson comorbidity index (OR: 1.15, 95% CI: 1.08-1.23), intracardiac abscess (OR:1.78, 95% CI:1.30-2.44), acute heart failure related to PVE (OR: 3. 11, 95% CI: 2.31-4.19), acute renal failure (OR: 3.11, 95% CI:1.14-2.09), septic shock (OR: 5.56, 95% CI:3.55-8.71), persistent bacteremia (OR: 1.85, 95% CI: 1.21-2.83) and surgery indicated but not performed (OR: 2.08, 95% CI: 1.49-2.89). In-hospital mortality in patients with surgical indication according to guidelines was 31.3% in operated patients and 51.3% in non-operated patients (p<0.001). In the latter group, there were more cases of advanced age, comorbidity, hospital acquired PVE, PVE due to Staphylococcus aureus, septic shock, and stroke.

CONCLUSIONS

Not performing cardiac surgery in patients with PVE and surgical indication, according to guidelines, has a significant negative effect on in-hospital mortality. Strategies to better discriminate patients who can benefit most from surgery would be desirable.

Clinical impact of time to results from the microbiology laboratory in bloodstream infections caused by carbapenemase-producing Enterobacterales (TIME-CPE STUDY)

OBJECTIVES

To evaluate the impact of time to results (TTR) on the outcome of patients with carbapenemase-producing Enterobacterales bloodstream infections (CPE-BSI).

METHODS

Times-series study conducted from January 2014 to December 2021, selecting patients with first CPE-BSI episodes. Periods of intervention were defined according to implementation of diagnostic bundle tests in the microbiology laboratory: pre-intervention (January 2014-December 2017) and post-intervention (January 2018-December 2021). TTR was defined as time elapsed from positivity time of the blood culture bottles to physicians' notification of CPE-BSI episodes, and was evaluated in patients who received inappropriate empirical and switched to appropriate targeted treatment (switch group). Analysis of a composite unfavourable outcome (mortality at Day 30 and/or persistent and/or recurrent bacteraemia) was performed for the total episodes and in the switch group.

RESULTS

One hundred and nine episodes were analysed: 66 pre-intervention and 43 post-intervention. Compared with pre-intervention, patients in the post-intervention period were younger (68 versus 63 years, P = 0.04), had INCREMENT score > 7 (31.8% versus 53.5%, P = 0.02) and unfavourable outcome (37.9% versus 20.9%, P = 0.04). Proportion of TTR > 30 h was more frequent pre-intervention than post-intervention (61.7% versus 35.5%, P = 0.02). In multivariate analysis of the 109 episodes, source other than urinary or biliary (OR 2.76, 95% CI 1.11-6.86) was associated with unfavourable outcome, while targeted appropriate treatment trended to being protective (OR 0.17, 95% CI 0.03-1.00). Considering the switch group (n = 78), source other than urinary or biliary (OR 14.9, 95% CI 3.25-69.05) and TTR > 30 h (OR 4.72, 95% CI 1.29-17.22) were associated with unfavourable outcome.

CONCLUSIONS

Decreased TTR in the post-intervention period was associated with the outcome in patients with CPE-BSI episodes.

Identification of Nocardia and non-tuberculous Mycobacterium species by MALDI-TOF MS using the VITEK MS coupled to IVD and RUO databases

Identification of Nocardia and Mycobacterium species by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is still a challenging task that requires both suitable protein extraction procedures and extensive databases. This study aimed to evaluate the VITEK MS Plus system coupled with updated RUO (v4.17) and IVD (v3.2) databases for the identification of Nocardia spp. and Mycobacterium spp. clinical isolates. Sample preparation was carried out using the VITEK MS Mycobacterium/Nocardia kit for protein extraction. From 90 Nocardia spp. isolates analysed, 86 (95.6%) were correctly identified at species or complex level using IVD and 78 (86.7%) using RUO. Only two strains were misidentified as other species pertaining to the same complex. Among the 106 non-tuberculous Mycobacterium clinical isolates tested from a liquid culture medium, VITEK MS identified correctly at species or complex level 96 (90.6%) isolates in the IVD mode and 89 (84.0%) isolates in the RUO mode. No misidentifications were detected. Although the IVD mode was unable to differentiate members of the M. fortuitum complex, the RUO mode correctly discriminated M. peregrinum and M. septicum. The robustness and accuracy showed by this system allow its implementation for routine identification of these microorganisms in clinical laboratories.

Pneumocystis jirovecii Pneumonia Diagnostic Approach: Real-Life Experience in a Tertiary Centre

Pneumocystis jirovecii pneumonia (PJP) in immunocompromised patients entails high mortality and requires adequate laboratory diagnosis. We compared the performance of a real time-PCR assay against the immunofluorescence assay (IFA) in the routine of a large microbiology laboratory. Different respiratory samples from HIV and non-HIV-infected patients were included. The retrospective analysis used data from September 2015 to April 2018, which included all samples for which a P. jirovecii test was requested. A total of 299 respiratory samples were tested (bronchoalveolar lavage fluid (n = 181), tracheal aspirate (n = 53) and sputum (n = 65)). Forty-eight (16.1%) patients fulfilled the criteria for PJP. Five positive samples (10%) had only colonization. The PCR test was found to have a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 96%, 98%, 90% and 99%, compared to 27%, 100%, 100% and 87%, for the IFA, respectively. PJ-PCR sensitivity and specificity were >80% and >90% for all tested respiratory samples. Median cycle threshold values in definite PJP cases were 30 versus 37 in colonized cases (p < 0.05). Thus, the PCR assay is a robust and reliable test for the diagnosis PJP in all respiratory sample types. Ct values of ≥36 could help to exclude PJP diagnosis.

Real-world Use of Bezlotoxumab and Fecal Microbiota Transplantation for the Treatment of Clostridioides difficile Infection

Background

We aimed to describe the frequency of use and effectiveness of bezlotoxumab (BZX) and fecal microbiota transplantation (FMT) in patients with Clostridioides difficile infection (CDI) in real-world practice.

Methods

This was a retrospective study conducted in a university hospital in which adult patients treated with BZX or FMT from January 2018 to April 2021 were included. The primary objective was to evaluate the effectiveness of BZX and FMT in preventing early (within 8 weeks) and late (within 1 year) CDI recurrences (rCDI). A multivariate analysis of risk factors for early recurrence was performed.

Results

Of 1377 consecutive CDI episodes, 117 (8.5%) received BZX or FMT, with full information available for 100 of the episodes: 51 received BZX, and 49 received FMT. BZX was used mostly in immunosuppressed patients (66.7%) and in first episodes or first recurrences in 70.6% of the cases. FMT was prescribed only in CDI recurrences. Despite the different conditions of the patients, there were no significant differences between BZX and FMT in preventing early rCDI (19.6% vs 24.5%; P = .55) or late rCDI (9.8% vs 18.4%; P = .31). In the multivariate analysis, risk factors for recurrence were presence of ≥2 previous rCDI episodes (odds ratio [OR], 2.90; 95% CI, 1.03-8.63) and use of non-CDI antibiotics (OR, 3.45; 95% CI, 1.24-9.57).

Conclusions

BZX and FMT were infrequently used in real-world practice. Both treatments had similar effectiveness in preventing CDI recurrence despite their application to different populations.

Characterization of the gut microbiome of patients with Clostridioides difficile infection, patients with non-C. difficile diarrhea, and C. difficile-colonized patients

Introduction

Clostridioides difficile infection (CDI) is the main cause of nosocomial diarrhea in developed countries. A key challenge in CDI is the lack of objective methods to ensure more accurate diagnosis, especially when differentiating between true infection and colonization/diarrhea of other causes. The main objective of this study was to explore the role of the microbiome as a predictive biomarker of CDI.

Methods

Between 2018 and 2021, we prospectively included patients with CDI, recurrent CDI (R-CDI), non-CDI diarrhea (NO-CDI), colonization by C. difficile, and healthy individuals. Clinical data and fecal samples were collected. The microbiome was analyzed by sequencing the hypervariable V4 region of the 16S rRNA gene on an Illumina Miseq platform. The mothur bioinformatic pipeline was followed for pre-processing of raw data, and mothur and R were used for data analysis.

Results

During the study period, 753 samples from 657 patients were analyzed. Of these, 247 were from patients with CDI, 43 were from patients colonized with C. difficile, 63 were from healthy individuals, 324 were from NOCDI, and 76 were from R-CDI. We found significant differences across the groups in alpha and beta diversity and in taxonomic abundance. We identified various genera as the most significant biomarkers for CDI (Bacteroides, Proteus, Paraprevotella, Robinsoniella), R-CDI (Veillonella, Fusobacterium, Lactobacillus, Clostridium sensu stricto I), and colonization by C. difficile (Parabacteroides, Faecalicoccus, Flavonifractor, Clostridium XVIII).

Discussion

We observed differences in microbiome patterns between healthy individuals, colonized patients, CDI, R-CDI, and NOCDI diarrhea. We identified possible microbiome biomarkers that could prove useful in the diagnosis of true CDI infections. Further studies are warranted.

Clostridioides difficile infection epidemiology and clinical characteristics in COVID-19 pandemic

Information on Clostridioides difficile infection (CDI) in patients with COVID-19 is scarce and points to an overall decrease of episodes during the pandemic. This situation results paradoxical, as COVID-19 patients had long periods of hospital stay and high use of antibiotics. We conducted a retrospective study from January 1st 2019 to December 31st 2020 comparing the incidence of hospital-acquired episodes of CDI (HA-CDI) among patients with and without COVID-19 admitted to our institution. During the study period, there were 47,048 patient admissions in 2019, 35,662 admissions of patients without COVID-19 in 2020 and 6,763 of COVID-19 patients. There were 68 episodes of HA-CDI in COVID-19 patients (14.75/10,000 days), 159 in 2020-non-COVID-19 patients (5.54/10,000 days) and 238 in 2019 (6.80/10,000 days). Comparison of HA-CDI in COVID-19 and non-COVID-19 patients indicates it occurs more frequently, in terms of CDI disease severity, COVID-19 does not seem to have a negative impact.

Abiotrophia spp. and Granulicatella spp. Infective Endocarditis: A Contemporary Perspective

BACKGROUND

Abiotrophia spp. and Granulicatella spp. are Gram-positive cocci, formerly known as nutritionally variant or deficient Streptococcus. Their role as causative agents of infective endocarditis (IE) is numerically uncertain, as well as diagnostic and clinical management of this infection. The aim of our study is to describe the clinical, microbiological, therapeutic, and prognosis of patients with IE caused by these microorganisms in a large microbiology department.

METHODS

Retrospective analysis of all the patients with Abiotrophia spp. and Granulicatella spp. IE registered in our centre in the period 2004-2021.

RESULTS

Of the 822 IE in the study period, 10 (1.2%) were caused by Abiotrophia spp. (7) or Granulicatella spp. (3). The species involved were A.defectiva (7), G.adiacens (2) and G.elegans (1). Eight patients were male, their mean age was 46 years and four were younger than 21 years. The most frequent comorbidities were congenital heart disease (4; 40%) and the presence of intracardiac prosthetic material (5; 50%). IE occurred on 5 native valves and 5 prosthetic valve or material. Blood cultures were positive in 8/10 patients, within a mean incubation period of 18.07 hours. In the other two patients, a positive 16SPCR from valve or prosthetic material provided the diagnosis. Surgery for IE was performed in seven patients (70%) and in all cases positive 16S rRNA PCR and sequencing from valve or prosthetic material was demonstrated. Valves and/or prosthetic removed material cultures were positive in four patients. Nine patients received ceftriaxone (4 in monotherapy and 5 in combination with other antibiotics). The mean length of treatment was 6 weeks and IE-associated mortality was 20% at one year follow-up.

CONCLUSIONS

Abiotrophia spp. or Granulicatella spp. IE were infrequent but not exceptional in our environment and particularly affected patients with congenital heart disease or prosthetic material. Blood cultures and molecular methods allowed the diagnosis. Most of them required surgery and the associated mortality, in spite of a mean age of 46 years, was high.

[Argentine registry of office blood pressure monitoring. RAMPAC study]

INTRODUCTION

Hypertension (HTN) is the leading cause of mortality and disability in the world. In Argentina, almost 44% of hypertensives do not know about their condition and this may be due to the low rate of blood pressure (BP) measurements during the office visit. Our hypothesis is that the measurement and electronic recording of BP (BPMR) is not a routine practice in Argentina.

OBJECTIVE

To describe the rate of office BP measurement in Argentina.

METHODS

This is a retrospective, multicentre, point prevalence study. We analysed all office visits on 9/19/2019 at 9 medical institutions in 6 provinces of Argentina.

RESULTS

Two thousand and eighty-two office visits were analysed. The patients' mean age was 52.1 years (18-103), 1790 (59.7%) were female, and 702 (36.1%) were hypertensives. BP was measured in 420 visits (14.1%; 95% CI 12.8-15.4). In a multivariate logistic regression model, history of HTN (OR 1.91, P<.001) and previous cardiovascular event (OR 1.76, P<.001) were associated with more odds of BPMR. The presence of cancer was associated with fewer odds of BPMR (OR .51, P<.01). Cardiology measured BP up to 49.5% (144/291 visits), followed by internal medicine 30% (152/507 visits).

CONCLUSION

BPMR during office visits is deficient in Argentina and represents a missed healthcare opportunity. Different strategies are needed to detect hypertensive patients and reduce cardiovascular events.

Identifying Anaerobic Bacteria Using MALDI-TOF Mass Spectrometry: A Four-Year Experience

Because of the special culture requirements of anaerobic bacteria, their low growth-rate and the difficulties to isolate them, MALDI-TOF MS has become a reliable identification tool for these microorganisms due to the little amount of bacteria required and the accuracy of MALDI-TOF MS identifications. In this study, the performance of MALDI-TOF MS for the identification of anaerobic isolates during a 4-year period is described. Biomass from colonies grown on Brucella agar was directly smeared onto the MALDI-TOF target plate and submitted to on-plate protein extraction with 1μl of 100% formic acid. Sequencing analysis of the 16S rRNA gene was used as a reference method for the identification of isolates unreliably or not identified by MALDI-TOF MS. Overall, 95.7% of the isolates were identified to the species level using the updated V6 database vs 93.8% with previous databases lacking some anaerobic species; 68.5% of the total were reliably identified with high-confidence score values (≥2.0) and 95.0% with low-confidence values (score value ≥1.7). Besides, no differences between Gram-positive and Gram-negative isolates were detected beyond a slight decrease of correct species assignment for gram positive cocci (94.1% vs 95.7% globally). MALDI-TOF MS has demonstrated its usefulness for the identification of anaerobes, with high correlation with phenotypic and conventional methods. Over the study period, only 2.1% of the isolates could not be reliably identified and required molecular methods for a final identification. Therefore, MALDI-TOF MS provided reliable identification of anaerobic isolates, allowing clinicians to streamline the most appropriate antibiotic therapy and manage patients accordingly.

Sample pooling is efficient in PCR testing of SARS-CoV-2: a study in 7400 healthcare professionals

SARS-CoV-2 pandemic shows the importance of having efficient virus diagnosis, especially in groups of particular relevance such as health care professionals, without involving a large economic expense. This is a prevalence study carried out in 7400 health care professionals in a 1350-bed hospital in Madrid, Spain. Pools of 10 samples were performed, using the Xpert® Xpress SARS-CoV-2 test for the diagnosis from clinical samples of nasopharyngeal exudate. A previous study was performed to evaluate the effect of the dilution in terms of sensitivity. The estimated sensitivity was over 95%. A total of 740 pools were performed, with a final result of 218 health care professionals being positive. Using the pooling system, the reagent cost reduction to the institution was 75.3%. It can be concluded that the described sample pooling system is a useful and efficient tool in the diagnosis of SARS-CoV-2 in certain groups, assuming a cost reduction without reducing the sensitivity.

Case Report: Severe ARDS in a Pediatric Hematopoietic Stem-Cell Transplantation Recipient Caused by Disseminated Toxoplasmosis

Toxoplasma gondii infection is a severe complication of hematopoietic stem-cell transplantation (HSCT) recipients that can remain unnoticed without a high clinical suspicion. We present the case of a 6-year-old patient with acute lymphoblastic leukemia and HSCT recipient who was admitted to the Pediatric Intensive Care Unit (PICU) on post-transplantation day +39 with fever, hypotension, severe respiratory distress and appearance of a lumbar subcutaneous node. She developed severe Acute Respiratory Distress Syndrome (ARDS) and underwent endotracheal intubation and early mechanical ventilation. Subsequently, she required prone ventilation, inhaled nitric oxide therapy and high-frequency oscillatory ventilation (HFOV). An etiologic study was performed, being blood, urine, bronchoalveolar lavage and biopsy of the subcutaneous node positive for Toxoplasma gondii by Polymerase Chain Reaction (PCR). Diagnosis of disseminated toxoplasmosis was established and treatment with pyrimethamine, sulfadiazine and folinic acid started. The patient showed clinical improvement, allowing weaning of mechanical ventilation and transfer to the hospitalization ward after 40 days in the PICU. It is important to consider toxoplasmosis infection in immunocompromised patients with sepsis and, in cases of severe respiratory distress, early mechanical ventilation should be started using the open lung approach. In Toxoplasma IgG positive patients, close monitoring and appropriate anti-infectious prophylaxis is needed after HSCT.

The Mars Environmental Dynamics Analyzer, MEDA. A Suite of Environmental Sensors for the Mars 2020 Mission

NASA's Mars 2020 (M2020) rover mission includes a suite of sensors to monitor current environmental conditions near the surface of Mars and to constrain bulk aerosol properties from changes in atmospheric radiation at the surface. The Mars Environmental Dynamics Analyzer (MEDA) consists of a set of meteorological sensors including wind sensor, a barometer, a relative humidity sensor, a set of 5 thermocouples to measure atmospheric temperature at ∼1.5 m and ∼0.5 m above the surface, a set of thermopiles to characterize the thermal IR brightness temperatures of the surface and the lower atmosphere. MEDA adds a radiation and dust sensor to monitor the optical atmospheric properties that can be used to infer bulk aerosol physical properties such as particle size distribution, non-sphericity, and concentration. The MEDA package and its scientific purpose are described in this document as well as how it responded to the calibration tests and how it helps prepare for the human exploration of Mars. A comparison is also presented to previous environmental monitoring payloads landed on Mars on the Viking, Pathfinder, Phoenix, MSL, and InSight spacecraft.

Characterization of the virulence of Pseudomonas aeruginosa strains causing ventilator-associated pneumonia

Background

The objective of this study was to evaluate the virulence of P. aeruginosa ventilator-associated pneumonia (VAP) strains (cases) in terms of biofilm production and other phenotypic and genotypic virulence factors compared to P. aeruginosa strains isolated from other infections (controls).

Methods

Biofilm production was tested to assess biomass production and metabolic activity using crystal violet binding assay and XTT assay, respectively. Pigment production (pyocyanin and pyoverdine) was evaluated using cetrimide agar. Virulence genes were detected by conventional multiplex PCR and virulence was tested in an in vivo model in Galleria mellonella larvae.

Results

We did not find statistically significant differences between VAP and no-VAP strains (p > 0.05) regarding biofilm production. VAP strains had no production of pyocyanin after 24 h of incubation (p = 0.023). The distribution of virulence genes between both groups were similar (p > 0.05). VAP strains were less virulent than non-VAP strains in an in vivo model of G. mellonella (p < 0.001).

Conclusion

The virulence of VAP-Pseudomonas aeruginosa does not depend on biofilm formation, production of pyoverdine or the presence of some virulence genes compared to P. aeruginosa isolated from non-invasive locations. However, VAP strains showed attenuated virulence compared to non-VAP strains in an in vivo model of G. mellonella.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12879-020-05534-1.

Revisiting nocardiosis at a tertiary care institution: Any change in recent years?

OBJECTIVE

To analyse relevant changes in incidence, clinical and microbiological characteristics of nocardiosis over the last 24 years at the current institution.

MATERIALS AND METHODS

The clinical records of patients with nocardiosis (2006-2018) were reviewed and then compared with a previous cohort (1995-2006). Nocardia isolates were identified by 5'-end-16S-rRNA-gene-PCR targeting the first 500 bp of the gene and sequencing. Susceptibility tests were determined by broth microdilution (CLSI guidelines).

RESULTS

Forty-two patients (64.3% male) with nocardiosis were evaluated in the recent cohort: 51.2% had COPD, 43.9% were on corticosteroid therapy and 31.7% had cancer. The incidence of nocardiosis varied from 6.3 to 7.1/100,000 admissions (p = 0.62). There was a decrease in HIV patients (27% vs. 4.9%, p = 0.01) and solid organ transplantation (SOT) recipients (18.9% vs. 2 .4%, p = 0.01). Cases with pulmonary involvement had increased (70.3% vs. 90.5%, p = 0.04). Nocardia species were similar but the most common were N. cyriacigeorgica (32.4% vs. 40.5%, p = 0.49) and N. farcinica (24.3% vs. 14.3%, p = 0.39). Antibiotic resistance remained stable: cotrimoxazole (10.8% vs. 5.7%, p = 0.68), imipenem (5.4% vs. 5.6%, p = 1.0); amikacin and linezolid were 100% active. No differences were found in breakthrough nocardiosis (21.6% vs. 9.8%, p = 0.21) or related mortality (21.6% vs. 21.4%, p = 1.0). The multivariate analysis confirmed that nocardiosis caused by N. farcinica is a risk factor for poor outcome (p = 0.045).

CONCLUSIONS

Nocardiosis incidence has remained stable. It mainly affected elderly patients with chronic respiratory conditions and those on corticosteroid treatment. Infections in HIV and SOT patients have practically disappeared. Pulmonary involvement remains the most common area to be affected. Nocardiosis caused by N. farcinica is apparently a risk factor for poor clinical outcome.

Clinical impact of a Clostridioides (Clostridium) difficile bedside infectious disease stewardship intervention

Objectives

To evaluate the clinical impact of a bedside visit to patients with a positive Clostridioides difficile test on the antimicrobial stewardship of C. difficile infection (CDI) and non-C. difficile infections.

Methods

All patients ≥18 years old with positive CDI laboratory tests hospitalized between January 2017 and August 2017 received an immediate bedside intervention that consisted mainly of checking protective measures and providing recommendations on infection control and the management of CDI and other infections.

Results

A total of 214 patients were evaluated. The infectious disease (ID) physician was the first to establish protective measures in 25.2% of the cases. In 22/29 (75.9%) cases, physicians in charge accepted ID consultant recommendations to stop CDI treatment in asymptomatic patients. Unnecessary non-CDI antibiotics were discontinued in 19.1% of the cases. ID recommendations were not accepted by physicians in charge in only 12.6% of the cases.

Conclusions

A bedside rapid intervention for patients with a CDI-positive faecal sample was effective in avoiding overdiagnosis and unnecessary antibiotic treatment, optimizing anti-CDI drugs, increasing compliance with infection control measures and providing educational advice.

In-Depth Study of a Nosocomial Outbreak Caused by Extensively Drug-Resistant Pseudomonas aeruginosa Using Whole Genome Sequencing Coupled With a Polymerase Chain Reaction Targeting Strain-Specific Single Nucleotide Polymorphisms

In 2013-2014, an outbreak involving 14 patients infected by an extensively drug-resistant strain of Pseudomonas aeruginosa was detected in a hospital in Madrid, Spain. Our objective was to evaluate an alternative strategy for investigating the outbreak in depth by means of molecular and genomic approaches. Pulsed-field gel electrophoresis (PFGE) was applied as a first-line approach, followed by a more refined whole genome sequencing analysis. Single nucleotide polymorphisms identified by whole genome sequencing were used to design a specific polymerase chain reaction (PCR) for screening unsuspected cases infected by the outbreak strain. Whole genome sequencing alerted us to the existence of greater genetic diversity than was initially assumed, splitting the PFGE-associated outbreak isolates into 4 groups, 2 of which represented coincidental transmission unrelated to the outbreak. A multiplex allele-specific PCR targeting outbreak-specific single nucleotide polymorphisms was applied to 290 isolates, which allowed us to identify 25 additional cases related to the outbreak during 2011-2017. Whole genome sequencing coupled with an outbreak-strain-specific PCR enabled us to markedly redefine the initial picture of the outbreak by 1) ruling out initially suspected cases, 2) defining likely independent coincidental transmission events, 3) predating the starting point of the outbreak, 4) capturing new unsuspected cases, and 5) revealing that the outbreak was still active.

Interregional spread in Spain of linezolid-resistant Enterococcus spp. isolates carrying the optrA and poxtA genes

The emergence of linezolid-resistant Enterococcus spp. (LRE) due to transferable resistance determinants is a matter of concern. To understand the contribution of the plasmid-encoded optrA and poxtA genes to the emergence of LRE, clinical isolates from different Spanish hospitals submitted to the Spanish Reference Laboratory from 2015-2018 were analysed. Linezolid resistance mechanisms were screened in all isolates by PCR and sequencing. Genetic relatedness of Enterococcus spp. carrying optrA and poxtA was studied by PFGE and MLST. Antimicrobial susceptibility was tested by broth microdilution using EUCAST standards. A total of 97 LRE isolates were studied, in 94 (96.9%) of which at least one resistance determinant was detected; 84/97 isolates (86.6%) presented a single resistance mechanism as follows: 45/84 (53.6%) carried the optrA gene, 38/84 (45.2%) carried the G2576T mutation and 1/84 (1.2%) carried the poxtA gene. In addition, 5/97 isolates (5.2%) carried both optrA and the G2576T mutation and 5/97 (5.2%) carried both optrA and poxtA. The optrA gene was more frequent in Enterococcus faecalis (83.6%) than Enterococcus faecium (11.1%) and was mainly associated with community-acquired urinary tract infections. Carriage of the poxtA gene was more frequent in E. faecium (13.9%) than E. faecalis (1.6%). Among the optrA-positive E. faecalis isolates, two main clusters were detected by PFGE. These two clusters belonged to ST585 and ST480 and were distributed throughout 11 and 6 Spanish provinces, respectively. This is the first description of LRE carrying the poxtA gene in Spain, including the co-existence of optrA and poxtA in five isolates.

Three different patterns of positive Clostridium difficile laboratory tests. A comparison of clinical behavior

Clostridium difficile (CD) diagnosis is very varied and under discussion. Different research groups disagree on the clinical significance of patients with negative direct toxin and positive polymerase chain reaction (PCR) or even more with direct toxin and glutamate dehydrogenase (GDH) both negatives, but CD detected by toxigenic culture (TC). The objective was to analyze the characteristics of patients with 3 different diagnostic criteria. We compared these 3 groups of patients: group 1: (GDH+/direct toxin+/PCR+), group 2: (GDH+/direct toxin-/PCR+) and group 3: (GDH-/direct toxin-/PCR not done/TC+). The proportion of patients with CD infection (CDI) (not colonization) for groups 1 to 3 was, respectively, 90.3%, 95.4%, and 59.1%. No differences between severity (40.8%, 38.5%, 27.3%), recurrence (20.3%, 24.1%, 7.6%), or related mortality (12.5%, 5.2%, 0%) were found within the 3 groups of patients. Laboratory clinical results should not be used as the only tool to differentiate CDI versus colonization or severity. We recommend that PCR or a second-look TC be performed on all patients.

Faecal microbiota transplantation for recurrent Clostridioides difficile infection: experience with lyophilized oral capsules

BACKGROUND

Faecal microbiota transplantation (FMT) is a highly effective approach for refractory and recurrent Clostridioides difficile infection (CDI). Despite its excellent efficacy, FMT is not yet a routine procedure in most centres. There is very little experience with FMT based on lyophilized capsules, and data from European institutions are lacking. This article describes our experience with FMT to treat recurrent CDI using lyophilized oral capsules.

METHODS

A prospectively recorded single-centre case series of patients with recurrent CDI who underwent FMT between January 2018 and May 2019 were analysed. The primary outcome was defined as resolution of CDI without recurrences over a two-month period. Overall resolution was defined as resolution of diarrhoea without recurrence of CDI within two months after a further cycle of FMT. The FMT process involved oral ingestion of four or five lyophilized capsules in a single dose. All stool donors were rigorously screened.

FINDINGS

FMT was performed in 32 patients. Primary cure was achieved in 81.3% of patients, and the overall cure rate was 87.5%. FMT via lyophilized capsules was well tolerated. No FMT procedure-related adverse events and no further complications were observed for lyophilized-capsule FMT.

CONCLUSIONS

This initial clinical experience suggests that FMT based on oral lyophilized preparations is a safe, well-tolerated, and highly effective treatment for recurrent CDI. Administration of oral lyophilized capsules seems feasible in hospital routine and will enable FMT to be more widely used.

Prediction of poor outcome in Clostridioides difficile infection: A multicentre external validation of the toxin B amplification cycle

Classification of patients according to their risk of poor outcomes in Clostridioides difficile infection (CDI) would enable implementation of costly new treatment options in a subset of patients at higher risk of poor outcome. In a previous study, we found that low toxin B amplification cycle thresholds (C_t) were independently associated with poor outcome CDI. Our objective was to perform a multicentre external validation of a PCR-toxin B C_t as a marker of poor outcome CDI. We carried out a multicentre study (14 hospitals) in which the characteristics and outcome of patients with CDI were evaluated. A subanalysis of the results of the amplification curve of real-time PCR gene toxin B (XpertTM C. difficile) was performed. A total of 223 patients were included. The median age was 73.0 years, 50.2% were female, and the median Charlson index was 3.0. The comparison of poor outcome and non-poor outcome CDI episodes revealed, respectively, the following results: median age (years), 77.0 vs 72.0 (p = 0.009); patients from nursing homes, 24.4% vs 10.8% (p = 0.039); median leukocytes (cells/μl), 10,740.0 vs 8795.0 (p = 0.026); and median PCR-toxin B C_t, 23.3 vs 25.4 (p = 0.004). Multivariate analysis showed that a PCR-toxin B C_t cut-off <23.5 was significantly and independently associated with poor outcome CDI (p = 0.002; OR, 3.371; 95%CI, 1.565-7.264). This variable correctly classified 68.5% of patients. The use of this microbiological marker could facilitate early selection of patients who are at higher risk of poor outcome and are more likely to benefit from newer and more costly therapeutic options.

New chromosomal lineages within Microvirga and Bradyrhizobium genera nodulate Lupinus angustifolius growing on different Tunisian soils

Thirty-one rhizobial isolates nodulating native Lupinus angustifolius (blue lupine) plants growing in Northern Tunisian soils were isolated and analysed using different chromosomal and symbiotic gene markers. Phylogenetic analyses based on recA partial sequences grouped them into at least five groups: four of them within the genus Bradyrhizobium (26 isolates) and one into the genus Microvirga (5 isolates). Representative strains were analysed by multilocus sequence analysis of three housekeeping genes rrs-recA-glnII and rrs-gyrB-dnaK for Bradyrhizobium and Microvirga isolates, respectively. Based on this analysis, eight isolates clustered with the previously described strains Bradyrhizobium lupini USDA3051 and Bradyrhizobium canariense BTA-1. However, five of the isolates clustered separately and may constitute a new species within the Bradyrhizobium genus. The remaining five isolates were closely related to the strain Microvirga sp. LmiM8 and may constitute a new Microvirga species. The analysis of the nodC gene showed that all Bradyrhizobium strains nodulating blue lupine belong to the symbiovar genistearum, whereas the Microvirga isolates are associated with the symbiovar mediterranense. The results of this study support that the L. angustifolius root nodule symbionts isolated in Northern Tunisia belong mostly to the B. canariense/B. lupini lineages. However, new clades of Bradyrhizobium and Microvirga have been identified as L. angustifolius endosymbionts.

Role of age and comorbidities in mortality of patients with infective endocarditis

PURPOSE

The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality.

METHODS

Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk.

RESULTS

A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32-3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39-1.88),and non-performed surgery (HR:1.64;95% CI:11.16-1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality.

CONCLUSION

There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group.

Antimicrobial management of Tropheryma whipplei endocarditis: the Spanish Collaboration on Endocarditis (GAMES) experience

OBJECTIVES

Tropheryma whipplei has been detected in 3.5% of the blood culture-negative cases of endocarditis in Spain. Experience in the management of T. whipplei endocarditis is limited. Here we report the long-term outcome of the treatment of previously reported patients who were diagnosed with infective endocarditis (IE) caused by T. whipplei from the Spanish Collaboration on Endocarditis-Grupo de Apoyo al Manejo de la Endocarditis Infecciosa en España (GAMES) and discuss potential options for antimicrobial therapy for IE caused by T. whipplei.

PATIENTS AND METHODS

Seventeen patients with T. whipplei endocarditis were recruited between 2008 and 2014 in 25 Spanish hospitals. Patients were classified according to the therapeutic regimen: ceftriaxone and trimethoprim/sulfamethoxazole, doxycycline + hydroxychloroquine and other treatment options.

RESULTS

Follow-up data were obtained from 14 patients. The median follow-up was 46.5 months. All patients completed the antibiotic treatment prescribed, with a median duration of 13 months. Six patients were treated with ceftriaxone and trimethoprim/sulfamethoxazole (median duration 13 months), four with doxycycline + hydroxychloroquine (median duration 13.8 months) and four with other treatment options (median duration 22.3 months). The follow-up after the end of the treatments was between 5 and 84 months (median 24 months).

CONCLUSIONS

All treatment lines were effective and well tolerated. Therapeutic failures were not detected during the treatment. None of the patients died or experienced a relapse during the follow-up. Only six patients received antibiotic treatment in accordance with guidelines. These data suggest that shorter antimicrobial treatments could be effective.

Epidemiological and clinical characteristics of Streptococcus tigurinus endocarditis

Background

Streptococcus tigurinus was recently described as a new streptococcal species within the viridans group streptococci (VGS). The objectives of the present work were to analyse the clinical and microbiological characteristics of S. tigurinus isolated from patients with bacteraemias, to determine the prevalence of S. tigurinus among VGS endocarditis in Spain, and to compare the clinical characteristics and outcomes of endocarditis caused by S. tigurinus and other VGS.

Methods

Retrospective nationwide study, performed between 2008 and 2016 in 9 Spanish hospitals from 7 different provinces comprising 237 cases of infective endocarditis. Streptococcal isolates were identified by sequencing fragments of their 16S rRNA, sodA and groEL genes. Clinical data of patients with streptococcal endocarditis were prospectively collected according to a pre-established protocol.

Results

Patients with endocarditis represented 7/9 (77.8%) and 26/86 (30.2%) of the bacteraemias caused by S. tigurinus and other VGS, respectively (p < 0.001), in two of the hospital participants. Among patients with streptococcal endocarditis, 12 different Streptococcus species were recognized being S. oralis, S. tigurinus and S. mitis the three more common. No relevant statistical differences were observed in the clinical characteristics and outcomes of endocarditis caused by the different VGS species.

Conclusions

In this multicenter study performed in Spain, S. tigurinus showed a higher predilection for the endocardial endothelium as compared to other VGS. However, clinical characteristics and outcomes of endocarditis caused by S. tigurinus did not significantly differ from endocarditis caused by other oral streptococci.

Fecal microbiota transplantation for recurrent Clostridium difficile infection: Experience, protocol, and results

OBJECTIVE

Fecal microbiota transplantation (FMT) is a highly effective therapy for recurrent Clostridium difficile infection (R-CDI). Despite its excellent efficacy, it is still not a routine procedure in most European centers. FMT has not been widely used in Spain to date. We describe our experience with FMT, including a novel approach based on oral fecal capsules.

METHODS

We analyzed a prospectively recorded case series of patients with R-CDI treated with FMT at a single center (June 2014-July 2017). Primary outcome was defined as resolution of CDI without recurrence in a two-month period. FMT was administered via colonoscopy, nasojejunal tube, or oral capsules. All stool donors were rigorously screened.

RESULTS

FMT was performed in 13 patients with R-CDI. Median age was 75.0 years and 76.9% were females. Six FMT were performed via nasojejunal tube, 5 via oral capsules, and 2 by colonoscopy. There were no procedure-related adverse events, except for bacteremia in one patient. During follow-up, R- CDI was observed in one patient at one month after FMT. The primary resolution rate was 83.3% and the overall resolution rate was 91.7%. FMT by capsules achieved a 100% resolution rate, colonoscopy 100%, and nasojejunal tube 80.0%.

CONCLUSIONS

In our cohort, FMT proved to be safe and effective, even in high risk patients. Oral administration in capsules also proved to be safe, well-tolerated, and highly effective for R-CDI. In our experience, the FMT capsule formulation seems feasible in the routine of a hospital. This administration method will allow FMT to be more widely used.

Identification of Porphyromonas isolates from clinical origin using MALDI-TOF Mass Spectrometry

Despite the wide implementation of MALDI-TOF MS for the rapid and reliable identification of most microorganisms, some taxonomic groups such as the Porphyromonas genus remain largely untested. In this study we evaluated the performance of MALDI-TOF MS on this genus using a collection of 39 isolates sent for routine identification to our institution over a 16-year period. All of them were identified by DNA-sequencing analysis of the 16S rRNA gene plus the hsp60 gene when the previous one did not yield species-level assignment. MALDI-TOF MS provided correct identification at least at the genus level of 21/39 isolates (53.9%). Twelve isolates were correctly identified at the species level with a score value ≥ 2.0 and 9 more with score values < 2.0 and ≥ 1.7. The species most represented in the database (P. gingivalis and P. somerae) lay within this category. However, the species poorly represented in this database (P. asaccharolytica and P. uenonis) were mostly identified with lower scores (1.35-1.67) or remained unidentified by MALDI-TOF MS. The addition of two P. asaccharolytica reference spectra to our in-house library allowed 72.9% of genus-level identifications with 17/37 isolates (45.9%) identified with score values ≥ 2.0. Our results showed a high level of correlation between MALDI-TOF MS and DNA-based identification for Porphyromonas spp. strains at the species level, even with score values < 2.0. The reliability provided by MALDI-TOF MS increased when the database was fed with spectra from the species poorly represented in the commercial database.

Identification of Nocardia species from clinical isolates using MALDI-TOF mass spectrometry

The identification of Nocardia isolates still represents a challenge for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) despite its acceptance for most bacterial and fungal isolates. In this study we evaluate the identification of Nocardia isolates using direct spotting and an updated database. Overall, 82 Nocardia isolates belonging to 13 species were identified by DNA sequence analysis of the 16S rRNA and secA1 genes. Nine of these well-characterized isolates from 6 Nocardia species were used to create an in-house library. The remaining 73 isolates were directly spotted on the target plate and on-plate protein extraction was performed. The protein spectra obtained were analyzed by MALDI-TOF MS using the BDAL database (Bruker Daltonics) updated with 6,903 MSPs or the combination of this commercial database and our in-house library. As a result, the use of the commercial database alone and in combination with the in-house library yielded 94.5% and 95.9% of correct species-level identifications, respectively, No isolate was misidentified at the genus level with either database. Besides, the use of the in-house library allowed the species-level identification of a N. otitidiscaviarum isolate that could only be identified at the genus-level with a score value <1.6 using the commercial database. In conclusion, the implementation of the direct spotting method and the in-house database provided a high rate of correct species assignment of Nocardia isolates despite the low number of isolates added. Further addition of well-characterized Nocardia isolates may ensure the rapid, accurate and inexpensive identification of most isolates encountered in the routine of the microbiology laboratory.

Bloodstream infection in patients with head and neck cancer: a major challenge in the cetuximab era

PURPOSE

To assess the impact of bloodstream infection (BSI) in patients with head and neck cancer (HNC) in the cetuximab era.

METHODS

We prospectively analysed the epidemiology, microbiology and outcomes of 51 BSI episodes occurring in 48 patients with HNC (2006-2017). We performed a retrospective matched-cohort study (1:2) to determine the risk factors for BSI. Finally, we compared patients who died with those who survived to identify risk factors for mortality.

RESULTS

The most frequent HNC localization was the oropharynx (43%), and pneumonia was the most frequent source (25%). Gram-positive BSI occurred in 55% cases, mainly due to Streptococcus pneumoniae (21%), and among Gram-negatives, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae were the most frequent. Hypoalbuminemia (OR 8.4; 95% CI, 3.5-19.9), previous chemotherapy (OR, 3.2; 95% CI, 1.3-7.4) and cetuximab therapy (OR, 2.8; 95% CI, 1.6-6.7) were significant risk factors for BSI. Patients with BSI had a higher overall case-fatality rate than patients without BSI (OR, 4.4; 95% CI, 1.7-11.8). Hypoalbuminemia was an independent risk factor for the early (7 day) and overall (30 day) case-fatalities, with ORs of 0.8 (95% CI, 0.6-0.9) and 0.8 (95% CI, 0.7-0.97), respectively. The presence of comorbidities (OR, 7; 95% CI, 1.4-34) was also an independent risk factor for overall case-fatality.

CONCLUSIONS

BSI causes high mortality in patients with HNC and is most often secondary to pneumonia. It occurs mainly among patients with hypoalbuminemia who receive treatment with cetuximab or chemotherapy. The development of BSI in patients with HNC impairs their outcome, especially in the presence of hypoalbuminemia and comorbidities.

Rifaximin-resistant Clostridium difficile strains isolated from symptomatic patients

BACKGROUND

Rifaximin has been proposed as an alternative treatment for specific cases of Clostridium difficile infection (CDI) and intestinal decontamination. Rifaximin-resistant C. difficile has occasionally been reported. Antibiotic susceptibility testing relies on anaerobic agar dilution (reference method), which is cumbersome and not routinely used. There is no commercial test for detection of resistance to rifaximin.

OBJECTIVES

To assess resistance to rifaximin by C. difficile and to evaluate the correlation between the results of the rifampicin E-test and susceptibility to rifaximin.

METHODS

We compared the in vitro susceptibility of clinical CDI isolates to rifaximin over a 6-month period using the agar dilution method with susceptibility to rifampicin using the E-test. All isolates were characterized using PCR-ribotyping. Clinical data were recorded prospectively.

RESULTS

We recovered 276 consecutive C. difficile isolates and found that 32.2% of episodes were caused by rifaximin-resistant strains. The MICs for rifaximin ranged from <0.0009-256 mg/L, with a geometric mean (GM) of 0.256 mg/L, an MIC_50/90 of 0.015/>256 mg/L. Rifaximin and rifampicin MICs were comparable, and all strains classed as resistant by agar dilution were correctly classified as resistant by E-test. The most common ribotypes were 001 (37.2%), 078/126 (14.3%), and 014 (12.0%). Ribotype 001 exhibited the highest MICs for rifaximin.

CONCLUSIONS

Resistance to rifaximin was common; resistance rates were higher in ribotype 001 strains. Susceptibility to rifaximin determined by agar dilution correlated with susceptibility to rifampicin determined using the E-test, including rifaximin-resistant strains. Our results suggest that the rifampicin E-test is a valid method for the prediction of rifaximin-resistant C. difficile.

Prostate Tumor Overexpressed-1 (PTOV1) promotes docetaxel-resistance and survival of castration resistant prostate cancer cells

Metastatic prostate cancer is presently incurable. The oncogenic protein PTOV1, first described in prostate cancer, was reported as overexpressed and significantly correlated with poor survival in numerous tumors. Here, we investigated the role of PTOV1 in prostate cancer survival to docetaxel and self-renewal ability. Transduction of PTOV1 in docetaxel-sensitive Du145 and PC3 cells significantly increased cell survival after docetaxel exposure and induced docetaxel-resistance genes expression (ABCB1, CCNG2 and TUBB2B). In addition, PTOV1 induced prostatospheres formation and self-renewal genes expression (ALDH1A1, LIN28A, MYC and NANOG). In contrast, Du145 and PC3 cells knockdown for PTOV1 significantly accumulated in the G2/M phase, presented a concomitant increased subG1 peak, and cell death by apoptosis. These effects were enhanced in docetaxel-resistant cells. Analyses of tumor datasets show that PTOV1 expression significantly correlated with prostate tumor grade, drug resistance (CCNG2) and self-renewal (ALDH1A1, MYC) markers. These genes are concurrently overexpressed in most metastatic lesions. Metastases also show PTOV1 genomic amplification in significant co-occurrence with docetaxel-resistance and self-renewal genes. Our findings identify PTOV1 as a promoter of docetaxel-resistance and self-renewal characteristics for castration resistant prostate cancer. The concomitant increased expression of PTOV1, ALDH1A1 and CCNG2 in primary tumors, may predict metastasis and bad prognosis.

Accurate Differentiation of Streptococcus pneumoniae from other Species within the Streptococcus mitis Group by Peak Analysis Using MALDI-TOF MS

Despite the benefits of MALDI-TOF MS technology (Matrix-Assisted Laser Desorption-Ionization Time-Of-Flight Mass Spectrometry) reported worldwide and the continuous improving of the available databases, discrimination between Streptococcus pneumoniae and closely related species within the Streptococcus mitis group (SMG) using this methodology has been suboptimal. However, the accurate identification at the species level of this group of microorganisms is important for the appropriate management of infected patients. In this study, 216 SMG isolates -101 S. pneumoniae and 115 corresponding to 7 non-pneumococcal species within this group- were analyzed. All the isolates had been previously identified by conventional methods (optochin and bile solubility tests) and non-pneumococcal isolates were confirmed by sequence analysis (sodA and plys genes) when required. The isolates were also identified with the MALDI Biotyper 3.1 (Bruker Daltonics, Bremen, Germany) using an updated library containing 6,903 Main Spectra Profiles (MSPs). All the analyzed S. pneumoniae were correctly identified with MALDI-TOF MS at species level using the most updated database and all the non-pneumococcal SMG isolates were also identified at the group level. Several peaks (4,964.32, 6,888.90, and 9,516.46 m/z) have been found to be specific of S. pneumoniae, whilst a different set of peaks have proved to be present only in S. mitis (6,839.07 m/z) and S. oralis (5,297.61, 5822.53, and 6,839.07 m/z). Peak analysis allowed correct species assignment of 101/101 S. pneumoniae isolates (100%) and 102/105 S. mitis/oralis isolates (97.1%). Thus, the implementation of MALDI-TOF MS plus peak analysis for the identification of this group of microorganisms may provide precise species-level information that will allow the early implementation of directed antibiotic therapy.

C. difficile PCR-ribotype 023 might go undetected when using ChromId C. difficile agar

We compared the performance of the new chromogenic medium ChromID C. difficile with that of CLO agar. ChromID C. difficile agar is a sensitive medium that can accelerate the presumptive identification of C. difficile, however ribotype 023 might go undetected when using this chromogenic medium.

Evaluation of the Xpert Carba-R (Cepheid) Assay Using Contrived Bronchial Specimens from Patients with Suspicion of Ventilator-Associated Pneumonia for the Detection of Prevalent Carbapenemases

There is a critical need for rapid diagnostic methods for multidrug-resistant (MDR) pathogens in patients with a suspicion of ventilator-associated pneumonia (VAP). The Xpert Carba-R detects 5 targets for carbapenemase-producing organisms (bla_KPC, bla_NDM, bla_VIM, bla_OXA-48, and bla_IMP-1). Our objective was to evaluate the performance of this assay directly on bronchial aspirates and to correlate the cycle number for a positive result (Ct) with the bacterial count. Bronchial aspirates from patients with a suspicion of VAP were spiked with a dilution of 1 of 4 MDR organisms carrying the resistance genes detected by the test prepared to a final concentration of 10²−10⁵ cfu/mL. We used a ROC curve and provided areas under the curve (AUC) with their 95% confidence intervals (CI). A point of maximum sensitivity (Se) and specificity (Sp) was derived and validity indices were calculated. One hundred contrived tests were performed. Se and Sp were 100% for all bacterial counts. A positive sample with a Ct ≤24.7 corresponded to a count ≥10⁵ cfu/mL; if the Ct was within the range >24.7-≤26.9, this corresponded to a count ≥10⁴ cfu/mL. When the Ct was >26.9, this corresponded to a count <10⁴ cfu/mL. The Xpert Carba-R detects carbapenemase-producing organisms directly in contrived bronchial aspirates. Still, an important issue to consider is that the number of gene copies may vary according to many factors in vivo. If confirmed in further studies, the strong correlation observed between Ct values and the results of semiquantitative cultures suggests this test could serve to differentiate between infection and colonization in routine clinical practice.

Evaluation of MALDI-TOF MS (Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry) for routine identification of anaerobic bacteria

Information regarding the use of MALDI-TOF MS as an alternative to conventional laboratory methods for the rapid and reliable identification of bacterial isolates is still limited. In this study, MALDI-TOF MS was evaluated on 295 anaerobic isolates previously identified by 16S rRNA gene sequencing and with biochemical tests (Rapid ID 32A system, BioMérieux). In total, 85.8% of the isolates were identified by MALDI-TOF MS at the species level vs 49.8% using the Rapid ID 32A system (p < 0.0001). None of the isolates was discordantly identified at the genus level using MALDI-TOF MS and only 9 of them could not be identified using the method. Thus, our results show that MALDI-TOF MS is a robust and reliable tool for the identification of anaerobic isolates in the microbiology laboratory. Its implementation will reduce the turnaround time for a final identification and the number of isolates that require 16S rRNA sequencing.