Bacteremia due to Leuconostoc species: A 13-year single-center case series.

INTRODUCTION: Leuconostoc spp. are facultatively anaerobic Gram-positive cocci involved in cases of hospital-acquired bacteremia, mainly in immunocompromised hosts. The available data is scarce due to its uncommon presentation. METHODS: We describe all the episodes of Leuconostoc spp. bacteremia in a third level hospital in a 13-year period (2008-2021). RESULTS: Four cases of clinically relevant bacteremia were detected. All cases were categorized as catheter-related. The following risk factors were found: previous glycopeptide therapy (75%), use of parenteral nutrition (100%) and cancer (75%). All isolates showed susceptibility to beta-lactams. Catheter removal was performed and wide spectrum antimicrobials were administered, with clinical response in all cases except one. DISCUSSION: Apart from cancer and glycopeptide exposure, disruption of skin barrier and gastrointestinal conditions were identified as risk factors, as it was concordantly underlined in other case series. Susceptibility to beta-lactams is usually maintained. Catheter removal and administration of an active antibacterial therapy seem to be the best approach for Leuconostoc spp. catheter-related bacteremia.

First confirmation of importation and transmission in Spain of the newly identified SARS-CoV-2 B.1.1.7 variant.

INTRODUCTION: A newly identified SARS-CoV-2 variant, VOC202012/01 originating lineage B.1.1.7, recently emerged in the United Kingdom. The rapid spread in the UK of this new variant has caused other countries to be vigilant. MATERIAL AND METHODS: We based our initial screening of B.1.1.7 on the dropout of the S gene signal in the TaqPath assay, caused by the 69/70 deletion. Subsequently, we confirmed the B.1.1.7 candidates by whole genome sequencing. RESULTS: We describe the first three imported cases of this variant from London to Madrid, subsequent post-arrival household transmission to three relatives, and the two first cases without epidemiological links to UK. One case required hospitalization. In all cases, drop-out of gene S was correctly associated to the B.1.1.7 variant, as all the corresponding sequences carried the 17 lineage-marker mutations. CONCLUSION: The first identifications of the SARS-CoV-2 B.1.1.7 variant in Spain indicate the role of independent introductions from the UK coexisting with post-arrival transmission in the community, since the early steps of this new variant in our country.

Clinical impact of time-to-positivity of blood cultures on mortality in patients with Pseudomonas aeruginosa bacteremia.

OBJECTIVES: To investigate the impact of the time-to-positivity of blood cultures (TTP) on 30-day mortality in patients with Pseudomonas aeruginosa bacteremia. METHODS: All nonduplicated episodes of P. aeruginosa monomicrobial bacteremia in adult patients from January 2013 to February 2020 were analysed. Epidemiological and clinical data were collected. TTP of blood cultures for P. aeruginosa isolates was automatically recorded. Multivariate analysis identified factors predicting 30-day overall mortality. RESULTS: A total of 328 patients were identified. The median TTP for P. aeruginosa isolates was 15 h (interquartile range [IQR] 12-18 h). All multidrug-resistant and extensively drug-resistant (MDR/XDR) episodes were positive within the first 36 h. The 30-day mortality rate was 32.3%. The best cut-off value of the TTP for predicting mortality was 16 h (area under the receiver operating characteristic curve 0.62, 95% confidence interval [CI] 0.56-0.67, P = 0.001). The 30-day mortality rate was significantly higher in the TTP ≤16 h group (41.0% vs. 19.5%, P < 0.001). In a multivariate analysis, severe neutropenia (adjusted odds ratio [aOR] 2.67, 95% CI 1.4-5.09, P = 0.002), septic shock (aOR 3.21, 95% CI 1.57-5.89, P < 0.001), respiratory source (aOR 4.37, 95% CI 2.24-8.52, P < 0.001), nosocomial acquisition (aOR 1.99, 95% CI 1.06-3.71, P = 0.030), TTP ≤16 h (aOR 2.27, 95% CI 2.12-4.25, P = 0.010), and MDR/XDR phenotype (aOR 2.54, 95% CI 1.38-4.67, P = 0.002) were independently associated with 30-day mortality. CONCLUSIONS: A short TTP (≤16 h) was independently associated with increased 30-day mortality. After local validation, this routinely available microbiological parameter might be useful for guiding empirical antipseudomonal therapies and supporting the close monitoring of patients with P. aeruginosa bacteremia.

Genomic Analysis of Ceftazidime/Avibactam-Resistant GES-Producing Sequence Type 235 Pseudomonas aeruginosa Isolates.

The emergence of ceftazidime/avibactam (CZA) resistance among Guiana extended-spectrum ß-lactamase (GES)-producing Pseudomonas aeruginosa isolates has rarely been described. Herein, we analyze the phenotypic and genomic characterization of CZA resistance in different GES-producing P. aeruginosa isolates that emerged in our institution. A subset of nine CZA-resistant P. aeruginosa isolates was analyzed and compared with thirteen CZA-susceptible isolates by whole-genome sequencing (WGS). All CZA-resistant isolates belonged to the ST235 clone and O11 serotype. A variety of GES enzymes were detected: GES-20 (55.6%, 5/9), GES-5 (22.2%, 2/9), GES-1 (11.1%, 1/9), and GES-7 (11.1%, 1/9). WGS revealed the presence of two mutations within the blaGES-20 gene comprising two single-nucleotide substitutions, which caused aspartic acid/serine and leucine/premature stop codon amino acid changes at positions 165 (D165S) and 237 (L237X), respectively. No major differences in the mutational resistome (AmpC, OprD porin, and MexAB-OprM efflux pump-encoding genes) were found among CZA-resistant and CZA-susceptible isolates. None of the mutations that have been previously demonstrated to cause CZA resistance were observed. Different mutations within the blaGES-20 gene were documented in CZA-resistant GES-producing P. aeruginosa isolates belonging to the ST235 clone in our institution. Although further analysis should be performed, according to our results, other resistance mechanisms might be involved in CZA resistance.

Clinical and bacterial characteristics of Pseudomonas aeruginosa affecting the outcome of patients with bacteraemic pneumonia.

Few studies have assessed the clinical and bacterial characteristics of Pseudomonas aeruginosa (PA) bacteraemic pneumonia (BP) episodes. This study analysed all non-duplicate PA-BP episodes from a tertiary hospital in 2013-2017. Epidemiology, clinical data, antimicrobial therapy and outcomes were recorded. Whole-genome sequencing was performed on PA blood isolates. The impact on early and late overall mortality of host, antimicrobial treatment and pathogen factors was assessed by multivariate logistic regression analysis. Of 55 PA-BP episodes, 32 (58.2%) were caused by extensively drug-resistant (XDR) PA. ST175 (32.7%) and ST235 (25.5%) were the most frequent high-risk clones. ß-Lactamases/carbapenemases were detected in 29 isolates, including blaVIM-2 (27.2%) and blaGES type (25.5%) [blaGES-5 (20.0%), blaGES-1 (3.6%) and blaGES-20 (1.8%)]. The most prevalent O-antigen serotypes were O4 (34.5%) and O11 (30.9%). Overall, an extensive virulome was identified in all isolates. Early mortality (56.4%) was independently associated with severe neutropenia (aOR = 4.64, 95% CI 1.11-19.33; P = 0.035) and inappropriate empirical antimicrobial therapy (aOR = 5.71, 95% CI 1.41-22.98; P = 0.014). Additionally, late mortality (67.3%) was influenced by septic shock (aOR = 8.85, 95% CI 2.00-39.16; P = 0.004) and XDR phenotype (aOR = 5.46, 95% CI 1.25-23.85; P = 0.024). Moreover, specific genetic backgrounds [ST235, blaGES, gyrA (T83I), parC (S87L), exoU and O11 serotype] showed significant differences in patient outcomes. Our results confirm the high mortality associated with PA-BP. Besides relevant clinical characteristics and inappropriate empirical therapy, bacteria-specific genetics factors, such as XDR phenotype, adversely affect the outcome of PA-BP.

First confirmation of importation and transmission in Spain of the newly identified SARS-CoV-2 B.1.1.7 variant.

INTRODUCTION: A newly identified SARS-CoV-2 variant, VOC202012/01 originating lineage B.1.1.7, recently emerged in the United Kingdom. The rapid spread in the UK of this new variant has caused other countries to be vigilant. MATERIAL AND METHODS: We based our initial screening of B.1.1.7 on the dropout of the S gene signal in the TaqPath assay, caused by the 69/70 deletion. Subsequently, we confirmed the B.1.1.7 candidates by whole genome sequencing. RESULTS: We describe the first three imported cases of this variant from London to Madrid, subsequent post-arrival household transmission to three relatives, and the two first cases without epidemiological links to UK. One case required hospitalization. In all cases, drop-out of gene S was correctly associated to the B.1.1.7 variant, as all the corresponding sequences carried the 17 lineage-marker mutations. CONCLUSION: The first identifications of the SARS-CoV-2 B.1.1.7 variant in Spain indicate the role of independent introductions from the UK coexisting with post-arrival transmission in the community, since the early steps of this new variant in our country.

Genomic Epidemiology of SARS-CoV-2 in Madrid, Spain, during the First Wave of the Pandemic: Fast Spread and Early Dominance by D614G Variants.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first detected in Madrid, Spain, on 25 February 2020. It increased in frequency very fast and by the end of May more than 70,000 cases had been confirmed by reverse transcription-polymerase chain reaction (RT-PCR). To study the lineages and the diversity of the viral population during this first epidemic wave in Madrid we sequenced 224 SARS-CoV-2 viral genomes collected from three hospitals from February to May 2020. All the known major lineages were found in this set of samples, though B.1 and B.1.5 were the most frequent ones, accounting for more than 60% of the sequences. In parallel with the B lineages and sublineages, the D614G mutation in the Spike protein sequence was detected soon after the detection of the first coronavirus disease 19 (COVID-19) case in Madrid and in two weeks became dominant, being found in 80% of the samples and remaining at this level during all the study periods. The lineage composition of the viral population found in Madrid was more similar to the European population than to the publicly available Spanish data, underlining the role of Madrid as a national and international transport hub. In agreement with this, phylodynamic analysis suggested multiple independent entries before the national lockdown and air transportation restrictions.

Lack of clinical significance for molecular detection of respiratory viruses in bronchoalveolar lavage samples.

The clinical significance of molecular detection of respiratory viruses in bronchoalveolar lavage (BAL) samples is poorly defined. We performed an observational retrospective study including all patients who underwent a BAL procedure in our institution, regardless of the reason for bronchoscopy, from January 2015 to December 2018. Respiratory viruses were detected by real-time polymerase chain reaction with a commercial multiplex panel, and a cell culture was performed to detect cytomegalovirus and herpes simplex virus. Positive results were correlated with clinical symptoms and patients' characteristics. Of 540 BAL samples analyzed, 113 (20.9%) were positive for any respiratory virus. Viral detection was significantly associated with respiratory symptoms (83.2% vs. 68.9%, p = .004) and radiological infiltrates (67.3% vs. 52.2%, p = .006). The most frequent viruses detected were rhinovirus (42/113, 37.2%), influenza virus (20/113, 17.7%), and parainfluenza virus (PIV) (16/113, 14.2%). Respiratory pathogens codetections were found in 51/113 (45.1%) BAL samples, including more than one virus (16/51, 31.4%), fungi (8/51, 15.7%), and bacteria (9/51, 17.6%). Viral detection was significantly higher in immunocompromised patients (26.5% vs. 16.9%; p = .022). PIV and human metapneumovirus were mostly observed in lung (50.0%, 8/16) and hemopoietic transplant recipients (25%, 2/8), respectively, with clinical repercussions. Our data underline that molecular diagnosis allows identification of viral agents as the etiology of respiratory infections; however, the high frequency of codetections hinders identification of the agent responsible for the current respiratory symptomatology. Immunocompromised patients are the target population in whom to investigate the presence of respiratory viruses in their BAL samples.

Pathogenic characteristics of Pseudomonas aeruginosa bacteraemia isolates in a high-endemicity setting for ST175 and ST235 high-risk clones.

Multidrug-resistant (MDR) Pseudomonas aeruginosa represents a major clinical concern. The interplay between antimicrobial resistance and virulence of P. aeruginosa was investigated in in vitro and in vivo studies. Thirty-eight well-characterized (21 MDR and 17 non-MDR) P. aeruginosa strains from patients with bacteraemia were analysed. Resistance phenotype, carbapenemase production, clonal relatedness, type III secretion system genotype, O-antigen serotype, cytotoxicity (ability to lyse cells) on A549 cells, and virulence (lethality in nematodes) in a Caenorhabditis elegans model were investigated. MDR strains showed lower cytotoxicity (35.4 ± 21.30% vs. 45.0 ± 18.78 %; P = 0.044) and virulence (66.7% vs. 100%; P = 0.011) than non-MDR strains. However, the pathogenicity of MDR high-risk clones varied broadly, with ST235 and ST175 clones being the most and least cytotoxic (51.8 ± 10.59% vs. 11.0 ± 1.25%; P < 0.0001) and virulent ([100% vs. 73.1; P = 0.075] and [0% vs. 93.9%; P < 0.0001], respectively). The pathogenicity of the ST235 clone was similar to that of non-MDR strains, and its ability to lyse cells and high virulence were related with the exoU-positive genotype. Furthermore, the O11 serotype was more frequent among the ST235 clone and exoU-positive genotype strains and was also essential for the pathogenicity of P. aeruginosa. Our data suggest that the pathogenicity of MDR high-risk clones is the result not only of the resistance phenotype but also of the virulence genotype. These findings have implications for the clinical management of patients and infection control programmes.

Predictors of Mortality in Bloodstream Infections Caused by Pseudomonas aeruginosa and Impact of Antimicrobial Resistance and Bacterial Virulence.

Whether multidrug resistance (MDR) is associated with mortality in patients with Pseudomonas aeruginosa bloodstream infections (BSI) remains controversial. Here, we explored the prognostic factors of P. aeruginosa BSI with emphasis on antimicrobial resistance and virulence. All P. aeruginosa BSI episodes in a 5-year period were retrospectively analyzed. The impact in early (5-day) and late (30-day) crude mortality of host, antibiotic treatment, and pathogen factors was assessed by multivariate logistic regression analysis. Of 243 episodes, 93 (38.3%) were caused by MDR-PA. Crude 5-day (20%) and 30-day (33%) mortality was more frequent in patients with MDR-PA (34.4% versus 11.3%, P < 0.001 and 52.7% versus 21.3%, P < 0.001, respectively). Early mortality was associated with neutropenia (adjusted odds ratio [aOR], 9.21; 95% confidence interval [CI], 3.40 to 24.9; P < 0.001), increased Pitt score (aOR, 2.42; 95% CI, 1.34 to 4.36; P = 0.003), respiratory source (aOR, 3.23; 95% CI,2.01 to 5.16; P < 0.001), inadequate empirical therapy (aOR, 4.57; 95% CI, 1.59 to 13.1; P = 0.005), shorter time to positivity of blood culture (aOR, 0.88; 95% CI, 0.80 to 0.97; P = 0.010), an exoU-positive genotype (aOR, 3.58; 95% CI, 1.31 to 9.79; P = 0.013), and the O11 serotype (aOR, 3.64; 95% CI, 1.20 to 11.1; P = 0.022). These risk factors were similarly identified for late mortality, along with an MDR phenotype (aOR, 2.18; 95% CI, 1.04 to 4.58; P = 0.040). Moreover, the O11 serotype (15.2%, 37/243) was common among MDR (78.4%, 29/37) and exoU-positive (89.2%, 33/37) strains. Besides relevant clinical variables and inadequate empirical therapy, pathogen-related factors such as an MDR phenotype, an exoU-positive genotype, and the O11 serotype adversely affect the outcome of P. aeruginosa BSI.

A short course of antibiotic treatment is safe after catheter withdrawal in catheter-related bloodstream infections due to coagulase-negative staphylococci.

CoNS is the main cause of catheter-related bloodstream infections (CRBSI). Current guidelines recommend catheter withdrawal followed by antibiotics for at least 5 days. We aimed to assess the efficacy and safety of a shorter course of antibiotherapy in patients with CoNS CRBSI. All proven cases of CoNS CRBSI at our institution (Jan 12/Dec 17) were retrospectively analysed. Comparison of clinical characteristics and outcomes between patients receiving a short (SC ≤ 3 days) versus long antibiotic course (LC > 3 days) was performed. Cox regression models predicting the risk for complications (including propensity score [PS] for treatment assignment as covariate) were designed to adjust baseline differences among both treatment groups. A total of 79 cases were included. Most patients (75.9%) showed clinical response at day 7 after catheter removal. Complications occurred in 3.8% (three cases of septic thrombophlebitis) with no cases of endocarditis. Microbiological relapse (MR) occurred in 13 patients (16.5%). SC and LC were administered to 25 (31.6%) and 54 (68.4%) patients, respectively, with no significant differences in MR-free survival between SC and LC groups (87.8 vs 86.3%; P = 0.6). In PS-adjusted Cox regression analyses, a tunnelled catheter as the source of CRBSI was the only independent risk factor for MR (hazard ratio, 5.71; 95% confidence interval, 1.6-21) whereas the duration of therapy had no apparent impact. Shortening antibiotic therapy to ≤ 3 days is not associated with a poorer outcome or a greater risk of MR in patients with CoNS CRBI with catheter withdrawal.

Bacteraemia due to extensively drug-resistant Pseudomonas aeruginosa sequence type 235 high-risk clone: Facing the perfect storm.

Predictors of mortality and the impact of multidrug resistance and virulence on patients with Pseudomonas aeruginosa (PA) bacteraemia were evaluated. Patients with PA bacteraemia in a 12-month period were retrospectively analysed. Carbapenemase production, molecular typing and identification of virulence factor ExoU were carried out. The activity of ceftolozane-tazobactam and ceftazidime-avibactam was also investigated. The primary endpoint was 30-day crude mortality. Of 64 patients with bacteraemia, 24 (37.5%) were caused by extensively drug-resistant PA (XDR-PA): 10 (41.7%) cases involved the VIM-2 carbapenemase-producing ST175 clone, 11 (45.8%) the GES-5 carbapenemase-producing ST235 clone, and 3 (12.5%) were non-carbapenemase producers. The exoU genotype was detected in all ST235 strains and in 6 (15%) of the non-XDR isolates. Ceftazidime-avibactam (58.3%) showed greater activity than ceftolozane-tazobactam (12.5%) against XDR-PA isolates, particularly in GES-5 producers (100%). The 30-day crude mortality rate in patients with XDR-PA bacteraemia was higher than in cases caused by susceptible strains (62.5% vs. 30%; P=0.02). Multivariate analysis showed that independent risk factors associated with 30-day crude mortality were Pitt score ≥2 (OR, 42.31; 95% CI, 4.88-366.7; P=0.001) and respiratory source of bacteraemia (OR, 49.13; 95% CI 3.89-620.5; P=0.003). Stratified analysis adjusting for respiratory source revealed a non-significant trend towards higher mortality in patients with bacteraemia caused by the ST235 clone and exoU-producing isolates. These data support the notion that the XDR phenotype associated with the GES-5 carbapenemase-producing ST235 clone and the exoU-positive genotype adversely affects the outcome of patients with PA bacteraemia, particularly those with respiratory tract infections and a severe clinical presentation.

Non-cooperative target recognition by means of singular value decomposition applied to radar high resolution range profiles.

Radar high resolution range profiles are widely used among the target recognition community for the detection and identification of flying targets. In this paper, singular value decomposition is applied to extract the relevant information and to model each aircraft as a subspace. The identification algorithm is based on angle between subspaces and takes place in a transformed domain. In order to have a wide database of radar signatures and evaluate the performance, simulated range profiles are used as the recognition database while the test samples comprise data of actual range profiles collected in a measurement campaign. Thanks to the modeling of aircraft as subspaces only the valuable information of each target is used in the recognition process. Thus, one of the main advantages of using singular value decomposition, is that it helps to overcome the notable dissimilarities found in the shape and signal-to-noise ratio between actual and simulated profiles due to their difference in nature. Despite these differences, the recognition rates obtained with the algorithm are quite promising.

Computational burden resulting from image recognition of high resolution radar sensors.

This paper presents a methodology for high resolution radar image generation and automatic target recognition emphasizing the computational cost involved in the process. In order to obtain focused inverse synthetic aperture radar (ISAR) images certain signal processing algorithms must be applied to the information sensed by the radar. From actual data collected by radar the stages and algorithms needed to obtain ISAR images are revised, including high resolution range profile generation, motion compensation and ISAR formation. Target recognition is achieved by comparing the generated set of actual ISAR images with a database of ISAR images generated by electromagnetic software. High resolution radar image generation and target recognition processes are burdensome and time consuming, so to determine the most suitable implementation platform the analysis of the computational complexity is of great interest. To this end and since target identification must be completed in real time, computational burden of both processes the generation and comparison with a database is explained separately. Conclusions are drawn about implementation platforms and calculation efficiency in order to reduce time consumption in a possible future implementation.