Comparing the in vitro efficacy of chlorhexidine and povidone-iodine in the prevention of post-surgical endophthalmitis

BACKGROUND

Intravitreal injections are a common ophthalmologic procedure. While infections following these injections are rare, they can lead to endophthalmitis, with potentially serious consequences. Various methods have been proposed to prevent endophthalmitis, including the use of antisepsis and antibiotics in patient preparation.

PURPOSE

To evaluate the antiseptic efficacy of aqueous chlorhexidine (CHX) and povidone-iodine (PI) when used alone and in combination with lidocaine gel (LG) in vitro.

METHODS

Two independent experimental trials were conducted. The first trial determined the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of CHX and PI against six bacterial strains. The second trial evaluated the bactericidal efficacy of the antiseptic agents (CHX 0.1% and PI 5%) and their combination with LG against the same bacterial strains.

RESULTS

CHX was more effective than PI in reducing the number of colonies forming units (cfus) of the tested bacteria. The order in which the antiseptic and LG were administered affected their effectiveness, with CHX administered before LG resulting in greater reduction of bacterial growth.

CONCLUSIONS

CHX 0.1% is more effective than PI 5% as an antiseptic agent. Application of CHX and PI prior to the use of lidocaine gel results in a more effective reduction of microorganisms.

Recommendations of the Spanish Antibiogram Committee (COESANT) for in vitro susceptibility testing of antimicrobial agents by disk diffusion

Disk diffusion is a well standardized method that provides reliable categorical results to guide antimicrobial therapy in numerous types of infections. Based on the guidelines of the European Committee on Antimicrobial Susceptibility Testing (EUCAST), which are widely implemented in Spain, the Spanish Antibiogram Committee (COESANT) has drawn up recommendations for antimicrobial selection by the disk diffusion technique, including selective reporting and its use for the detection of resistance mechanisms. Factors affecting disk diffusion results, along with advantages and shortcomings of the method, are also discussed.

The Interventions and Challenges of Antimicrobial Stewardship in the Emergency Department

Over the last decades, we have witnessed a constant increase in infections caused by multi-drug-resistant strains in emergency departments. Despite the demonstrated effectiveness of antimicrobial stewardship programs in antibiotic consumption and minimizing multi-drug-resistant bacterium development, the characteristics of emergency departments pose a challenge to their implementation. The inclusion of rapid diagnostic tests, tracking microbiological results upon discharge, conducting audits with feedback, and implementing multimodal educational interventions have proven to be effective tools for optimizing antibiotic use in these units. Nevertheless, future multicenter studies are essential to determine the best way to proceed and measure outcomes in this scenario.

Total Reference Air Kerma (TRAK) is Associated with Dosimetric Parameters in Template-Based High Dose-Rate (HDR) Interstitial Brachytherapy in Advanced Gynecologic Cancers

PURPOSE/OBJECTIVE(S)

To study TRAK and its association with dosimetric parameters in template-based high dose-rate interstitial brachytherapy in advanced gynecologic cancers.

MATERIALS/METHODS

Brachytherapy treatment plans of 53 patients treated between 2012 and 2022 at our institution with template-based Iridium-192 HDR brachytherapy, post-external beam RT, for locally advanced cancers of the cervix and vagina were retrospectively reviewed. Brachytherapy dose ranged from 25 to 30-Gy delivered in 4 to 6 fractions. The median number of flexi-guide catheters implanted was 18 (range 10-30). Clinical Target Volume (CTV) values were mean (±SD): 72.2 (±40.4) cm3 (high-risk, HR) and 182.2 (±73.7) cm3 (intermediate-risk, IR) respectively. TRAK per fraction (cGy at 1m), dose-volume information for the implant, target, and organ-at-risk (OAR) were recorded. Indices for dose coverage (CI), homogeneity (DHI), non-uniformity (DNR), overdose volume (ODI) were computed. Regression and correlation tests were used to study the TRAK relationship with various dosimetric parameters. The false discovery rate at a 5% level was corrected using the Benjamini-Hochberg procedure.

RESULTS

The average TRAK per fraction was 0.365 (±0.12) cGy. Mean and range values of plan quality indices were - CI 0.92 (0.7- 1.0), DHI 0.57 (0.41 - 0.77), DNR 0.43 (0.23 - 0.59) and ODI 0.22 (0.11 - 0.38), respectively Correlation results for TRAK with various dosimetric indices are presented in Table 1. TRAK showed a weak correlation with the number of flexi-guide catheters implanted (r = 0.35, p = 0.013). TRAK correlated strongly with target volumes (CTV_HR and CTV_IR and CTV_HR V100%) and with isodose volumes at both high (V300, V200, V150), and low dose levels (V90, V85, V50) (p<0.00001). TRAK correlated moderately with OAR 2-cm3 doses (p<0.00001). A weak correlation was observed between TRAK and plan quality indices.

CONCLUSION

TRAK correlates positively with target volume and volumes enclosed by isodoses at various dose levels in interstitial HDR brachytherapy of advanced Gynecologic Cancers. Interestingly, our study observed a comparatively stronger positive correlation between TRAK and Sigmoid 2-cm3 dose, equated to TRAK correlation with bladder, rectum, and small bowel 2-cm3 doses. This finding could interest future studies utilizing TRAK as a surrogate for treatment outcome and toxicity.

Significant increase of CTX-M-15-ST131 and emergence of CTX-M-27-ST131 Escherichia coli high-risk clones causing healthcare-associated bacteraemia of urinary origin in Spain (ITUBRAS-2 project)

OBJECTIVES

To assess the microbiological characteristics of Escherichia coli causing healthcare-associated bacteraemia of urinary origin (HCA-BUO) in Spain (ITUBRAS-2 project), with particular focus on ESBL producers and isolates belonging to ST131 high-risk clone (HiRC). Clinical characteristics and outcomes associated with ST131 infection were investigated.

METHODS

A total of 222 E. coli blood isolates were prospectively collected from patients with HCA-BUO from 12 tertiary-care hospitals in Spain (2017-19). Antimicrobial susceptibility and ESBL/carbapenemase production were determined. ST131 subtyping was performed. A subset of 115 isolates were selected for WGS to determine population structure, resistome and virulome. Clinical charts were reviewed.

RESULTS

ESBL-producing E. coli prevalence was 30.6% (68/222). ST131 represented 29.7% (66/222) of E. coli isolates and accounted for the majority of ESBL producers (46/68, 67.6%). The C2/H30-Rx subclone accounted for most ST131 isolates (44/66) and was associated with CTX-M-15 (37/44) and OXA-1 enzymes (27/44). Cluster C1-M27 was identified in 4/10 isolates belonging to subclade C1/H30-R1 and associated with CTX-M-27. Additionally, ST131 isolates showed a high content of other acquired resistance genes, and clade C/ST131 isolates carried characteristic QRDR mutations. They were categorized as uropathogenic E. coli and had higher aggregate virulence scores. ST131 infection was associated with more complex patients, prior use of cephalosporins and inadequate empirical treatment but was not associated with worse clinical outcomes.

CONCLUSIONS

ST131 HiRC is the main driver of ESBL-producing E. coli causing HCA-BUO in Spain, mainly associated with the expansion of subclade CTX-M-15-C2/H30-Rx and the emergence of CTX-M-27-C1/H30-R1 (Cluster C1-M27).

Acute Bacterial Meningitis in Healthy Adult Patients: A Prospective Cohort Study

Spontaneous bacterial meningitis (BM) is more common among patients with underlying conditions, but its characteristics in previously healthy patients are not well described. We analyzed the time trends of BM in terms of characteristics, and outcomes in patients without comorbidities.

PATIENTS AND METHODS

Single-center, prospective observational cohort study of 328 adults with BM hospitalized in a tertiary university hospital in Barcelona (Spain). We compared the features of infections diagnosed in 1982-2000 and 2001-2019. The main outcome measure was in-hospital mortality.

RESULTS

The median age of the patients increased from 37 to 45 years. Meningococcal meningitis significantly diminished (56% versus 31%, p < 0.000) whereas listerial meningitis increased (1.2% versus 8%, p = 0.004). Systemic complications were more common in the second period, although mortality did not vary significantly between periods (10.4% versus 9.2%). However, after adjusting for relevant variables, infection in the second period was associated with lower risk death.

CONCLUSIONS

Adult patients without underlying comorbidities that developed BM in recent years were older and more likely to have pneumococcal or listerial infections and systemic complications. In-hospital death was less likely in the second period, after adjusting for risk factors of mortality.

Outcomes of octogenarians and nonagenarians with Pseudomonas aeruginosa bacteremia: a multicenter retrospective study

BACKGROUND

P. aeruginosa bacteremia is a common and severe infection carrying high mortality in older adults. We aimed to evaluate outcomes of P. aeruginosa bacteremia among old adults (≥ 80 years).

METHODS

We included the 464/2394 (19%) older adults from a retrospective multinational (9 countries, 25 centers) cohort study of individuals hospitalized with P. aeruginosa bacteremia. Bivariate and multivariable logistic regression models were used to evaluate risk factors for 30-day mortality among older adults.

RESULTS

Among 464 adults aged ≥ 80 years, the mean age was 84.61 (SD 3.98) years, and 274 (59%) were men. Compared to younger patients, ≥ 80 years adults had lower Charlson score; were less likely to have nosocomial acquisition; and more likely to have urinary source. Thirty-day mortality was 30%, versus 27% among patients 65-79 years (n = 894) and 25% among patients < 65 years (n = 1036). Multivariate analysis for predictors of mortality among patients ≥ 80 years, demonstrated higher SOFA score (odds ratio [OR] 1.36, 95% confidence interval [CI] 1.23-1.51, p < 0.001), corticosteroid therapy (OR 3.15, 95% CI: 1.24-8.01, p = 0.016) and hospital acquired P. aeruginosa bacteremia (OR 2.30, 95% CI: 1.33-3.98, p = 0.003) as predictors. Appropriate empirical therapy within 24 h, type of definitive anti-pseudomonal drug, and type of regimen (monotherapy or combination) were not associated with 30-day mortality.

CONCLUSIONS

In older adults with P. aeruginosa bacteremia, background conditions, place of acquisition, and disease severity are associated with mortality, rather than the antimicrobial regimen. In this regard, preventive efforts and early diagnosis before organ failure develops might be beneficial for improving outcomes.

SAFETY AND EFFICACY OF THYMIC PEPTIDES IN THE TREATMENT OF HOSPITALIZED COVID-19 PATIENTS IN HONDURAS

Coronavirus disease 2019 (Covid-19) active cases continue to demand the development of safe and effective treatments. This is the first clinical trial to evaluate the safety and efficacy of oral thymic peptides. ; We conducted a nonrandomized phase 2 trial with a historic control group to evaluate the safety and efficacy of a daily 250-mg oral dose of thymic peptides in the treatment of hospitalized Covid-19 patients. Comparisons based on standard care from registry data were performed after propensity score matching. The primary outcomes were survival, time to recovery, and number of participants with treatment-related adverse events or side effects by day 20. ; A total of 44 patients were analyzed in this study: 22 in the thymic peptide group and 22 in the standard care group. There were no deaths in the intervention group compared to 24% mortality in standard care by day 20 (log-rank P=0.02). Kaplan-Meier analysis showed a significantly shorter time to recovery by day 20 in the thymic peptide group than in the standard care group (median, 6 days vs. 12 days; hazard ratio for recovery, 2.75 [95% confidence interval, 1.34 to 5.62]; log-rank P=0.002). No side effects or adverse events were reported. ; In patients hospitalized with Covid-19, the use of thymic peptides resulted in no side effects, adverse events, or deaths by day 20. Compared with the registry data, a significantly shorter time to recovery and mortality reduction were measured.

Clinical usefulness of quantifying microbial load from diabetic foot ulcers: A multicenter cohort study

AIMS

To evaluate if microbial load from diabetic foot ulcers (DFUs) can help in predicting outcomes.

METHODS

A multicenter prospective cohort study was performed in an outpatient setting (September 1, 2017-January 31, 2019) in diabetic patients with DFU.Quantitative cultures from DFU tissue biopsies at a baseline visit were obtained; high and low microbial loads were defined as ≥6logCFU/mL and <6logCFU/mL, respectively. Diagnosis of DFU infection was made and managed according to established guidelines. The outcome was evaluated at 6 month-visit as failure (persistence/new infection/amputation) or cure.

RESULTS

Out of 65 patients, 52 (80%) had long-standing DFUs (≥4 weeks), with high microbial load in 19 (29%).DFU infection (n = 24, 37%) was not associated with high microbial load in all patients but those with shorter DFU duration.Treatment failure occurred in 20/57 (35%) patients; high DFU microbial load was associated with worse outcome (n = 9/20, 45% failure rate, adjusted OR4.69; 95% CI, 1.22-18.09; p = 0.03),mainly due to the subgroup of patients with high microbial load and long-stand DFUs.

CONCLUSIONS

Since patients with high microbial load had a worse outcome, quantitative cultures from DFUs can identify patients who would benefit from antibiotic therapy.

CARB-ES-19 Multicenter Study of Carbapenemase-Producing Klebsiella pneumoniae and Escherichia coli From All Spanish Provinces Reveals Interregional Spread of High-Risk Clones Such as ST307/OXA-48 and ST512/KPC-3

Objectives

CARB-ES-19 is a comprehensive, multicenter, nationwide study integrating whole-genome sequencing (WGS) in the surveillance of carbapenemase-producing K. pneumoniae (CP-Kpn) and E. coli (CP-Eco) to determine their incidence, geographical distribution, phylogeny, and resistance mechanisms in Spain.

Methods

In total, 71 hospitals, representing all 50 Spanish provinces, collected the first 10 isolates per hospital (February to May 2019); CPE isolates were first identified according to EUCAST (meropenem MIC > 0.12 mg/L with immunochromatography, colorimetric tests, carbapenem inactivation, or carbapenem hydrolysis with MALDI-TOF). Prevalence and incidence were calculated according to population denominators. Antibiotic susceptibility testing was performed using the microdilution method (EUCAST). All 403 isolates collected were sequenced for high-resolution single-nucleotide polymorphism (SNP) typing, core genome multilocus sequence typing (cgMLST), and resistome analysis.

Results

In total, 377 (93.5%) CP-Kpn and 26 (6.5%) CP-Eco isolates were collected from 62 (87.3%) hospitals in 46 (92%) provinces. CP-Kpn was more prevalent in the blood (5.8%, 50/853) than in the urine (1.4%, 201/14,464). The cumulative incidence for both CP-Kpn and CP-Eco was 0.05 per 100 admitted patients. The main carbapenemase genes identified in CP-Kpn were bla_OXA–48 (263/377), bla_KPC–3 (62/377), bla_VIM–1 (28/377), and bla_NDM–1 (12/377). All isolates were susceptible to at least two antibiotics. Interregional dissemination of eight high-risk CP-Kpn clones was detected, mainly ST307/OXA-48 (16.4%), ST11/OXA-48 (16.4%), and ST512-ST258/KPC (13.8%). ST512/KPC and ST15/OXA-48 were the most frequent bacteremia-causative clones. The average number of acquired resistance genes was higher in CP-Kpn (7.9) than in CP-Eco (5.5).

Conclusion

This study serves as a first step toward WGS integration in the surveillance of carbapenemase-producing Enterobacterales in Spain. We detected important epidemiological changes, including increased CP-Kpn and CP-Eco prevalence and incidence compared to previous studies, wide interregional dissemination, and increased dissemination of high-risk clones, such as ST307/OXA-48 and ST512/KPC-3.

Duration of Treatment for Pseudomonas aeruginosa Bacteremia: a Retrospective Study

INTRODUCTION

There is no consensus regarding optimal duration of antibiotic therapy for Pseudomonas aeruginosa bacteremia. We aimed to evaluate the impact of short antibiotic course.

METHODS

We present a retrospective multicenter study including patients with P. aeruginosa bacteremia during 2009-2015. We evaluated outcomes of patients treated with short (6-10 days) versus long (11-15 days) antibiotic courses. The primary outcome was a composite of 30-day mortality or bacteremia recurrence and/or persistence. Univariate and inverse probability treatment-weighted (IPTW) adjusted multivariate analysis for the primary outcome was performed. To avoid immortal time bias, the landmark method was used.

RESULTS

We included 657 patients; 273 received a short antibiotic course and 384 a long course. There was no significant difference in baseline characteristics of patients. The composite primary outcome occurred in 61/384 patients in the long-treatment group (16%) versus 32/273 in the short-treatment group (12%) (p = 0.131). Mortality accounted for 41/384 (11%) versus 25/273 (9%) of cases, respectively. Length of hospital stay was significantly shorter in the short group [median 13 days, interquartile range (IQR) 9-21 days, versus median 15 days, IQR 11-26 days, p = 0.002]. Ten patients in the long group discontinued antibiotic therapy owing to adverse events, compared with none in the short group. On univariate and multivariate analyses, duration of therapy was not associated with the primary outcome.

CONCLUSIONS

In this retrospective study, 6-10 days of antibiotic course for P. aeruginosa bacteremia were as effective as longer courses in terms of survival and recurrence. Shorter therapy was associated with reduced length of stay and less drug discontinuation.

Extremely long-range, high-temperature Josephson coupling across a half-metallic ferromagnet

The Josephson effect results from the coupling of two superconductors across a spacer such as an insulator, a normal metal or a ferromagnet to yield a phase coherent quantum state. However, in junctions with ferromagnetic spacers, very long-range Josephson effects have remained elusive. Here we demonstrate extremely long-range (micrometric) high-temperature (tens of kelvins) Josephson coupling across the half-metallic manganite La_0.7Sr_0.3MnO₃ combined with the superconducting cuprate YBa₂Cu₃O₇. These planar junctions, in addition to large critical currents, display the hallmarks of Josephson physics, such as critical current oscillations driven by magnetic flux quantization and quantum phase locking effects under microwave excitation (Shapiro steps). The latter display an anomalous doubling of the Josephson frequency predicted by several theories. In addition to its fundamental interest, the marriage between high-temperature, dissipationless quantum coherent transport and full spin polarization brings opportunities for the practical realization of superconducting spintronics, and opens new perspectives for quantum computing.

Combination versus monotherapy as definitive treatment for Pseudomonas aeruginosa bacteraemia: a multicentre retrospective observational cohort study

BACKGROUND

Pseudomonas aeruginosa bacteraemia is a common and serious infection. No consensus exists regarding whether definitive combination therapy is superior to monotherapy. We aimed to evaluate the impact of combination therapy on mortality.

METHODS

This was a multicentre retrospective study (nine countries, 25 centres), including 1277 patients with P. aeruginosa bacteraemia during 2009-15. We evaluated the association between β-lactam plus aminoglycoside or quinolone combination therapy versus β-lactam monotherapy and mortality. The primary outcome was 30 day all-cause mortality. Univariate and multivariate Cox regression analyses were conducted, introducing combination as a time-dependent variable. Propensity score was conducted to adjust for confounding for choosing combination therapy over monotherapy.

RESULTS

Of 1119 patients included, 843 received definitive monotherapy and 276 received combination therapy (59% aminoglycoside and 41% quinolone). Mortality at 30 days was 16.9% (189/1119) and was similar between combination (45/276; 16.3%) and monotherapy (144/843; 17.1%) groups (P = 0.765). In multivariate Cox regression, combination therapy was not associated with reduced mortality (HR 0.98, 95% CI 0.64-1.53). No advantage in terms of clinical failure, microbiological failure or recurrent/persistent bacteraemia was demonstrated using combination therapy. Likewise, adverse events and resistance development were similar for the two regimens.

CONCLUSIONS

In this retrospective cohort, no mortality advantage was demonstrated using combination therapy over monotherapy for P. aeruginosa bacteraemia. Combination therapy did not improve clinical or microbiological failure rates, nor affect adverse events or resistance development. Our finding of no benefit with combination therapy needs confirmation in well-designed randomized controlled trials.

Large intrinsic anomalous Hall effect in SrIrO3 induced by magnetic proximity effect

The anomalous Hall effect (AHE) is an intriguing transport phenomenon occurring typically in ferromagnets as a consequence of broken time reversal symmetry and spin-orbit interaction. It can be caused by two microscopically distinct mechanisms, namely, by skew or side-jump scattering due to chiral features of the disorder scattering, or by an intrinsic contribution directly linked to the topological properties of the Bloch states. Here we show that the AHE can be artificially engineered in materials in which it is originally absent by combining the effects of symmetry breaking, spin orbit interaction and proximity-induced magnetism. In particular, we find a strikingly large AHE that emerges at the interface between a ferromagnetic manganite (La_0.7Sr_0.3MnO₃) and a semimetallic iridate (SrIrO₃). It is intrinsic and originates in the proximity-induced magnetism present in the narrow bands of strong spin-orbit coupling material SrIrO₃, which yields values of anomalous Hall conductivity and Hall angle as high as those observed in bulk transition-metal ferromagnets. These results demonstrate the interplay between correlated electron physics and topological phenomena at interfaces between 3d ferromagnets and strong spin-orbit coupling 5d oxides and trace an exciting path towards future topological spintronics at oxide interfaces.

Intraoperative Bacterial Contamination and Activity of Different Antimicrobial Prophylaxis Regimens in Primary Knee and Hip Replacement

Surgical antimicrobial prophylaxis (SAP) is important for the prevention of prosthetic joint infections (PJIs) and must be effective against the microorganisms most likely to contaminate the surgical site. Our aim was to compare different SAP regimens (cefazolin, cefuroxime, or vancomycin, alone or combined with gentamicin) in patients undergoing total knee (TKA) and hip (THA) arthroplasty. In this preclinical exploratory analysis, we analyzed the results of intraoperative sample cultures, the ratio of plasma antibiotic levels to the minimum inhibitory concentrations (MICs) for bacteria isolated at the surgical wound and ATCC strains, and serum bactericidal titers (SBT) against the same microorganisms. A total of 132 surgical procedures (68 TKA, 64 THA) in 128 patients were included. Cultures were positive in 57 (43.2%) procedures (mostly for coagulase-negative staphylococci and Cutibacterium spp.); the rate was lower in the group of patients receiving combination SAP (adjusted OR 0.475, CI95% 0.229-0.987). The SAP regimens evaluated achieved plasma levels above the MICs in almost all of intraoperative isolates (93/94, 98.9%) and showed bactericidal activity against all of them (SBT range 1:8-1:1024), although SBTs were higher in patients receiving cefazolin and gentamicin-containing regimens. The potential clinical relevance of these findings in the prevention of PJIs remains to be determined.

Do Prosthetic Joint Infections Worsen the Functional Ambulatory Outcome of Patients with Joint Replacements? A Retrospective Matched Cohort Study

OBJECTIVES

To assess the effect on the functional ambulatory outcome of postoperative joint infection (PJI) cured at the first treatment attempt versus not developing PJI in patients with hip and knee prostheses.

METHODS

In a single-hospital retrospectively matched cohort study, each patient with PJI between 2007 and 2016 was matched on age, sex, type of prosthesis and year of implantation with two other patients with uninfected arthroplasties. The definition of a PJI cure included infection eradication, no further surgical procedures, no PJI-related mortality and no suppressive antibiotics. Functional ambulatory status evaluated one year after the last surgery was classified into four simple categories: able to walk without assistance, able to walk with one crutch, able to walk with two crutches, and unable to walk. Patients with total hip arthroplasties (THA), total knee arthroplasties (TKA) and partial hip arthroplasty (PHA) were analysed separately.

RESULTS

A total of 109 PJI patients (38 TKA, 41 THA, 30 PHA) and 218 non-PJI patients were included. In a model adjusted for clinically relevant variables, PJI was associated with a higher risk of needing an assistive device for ambulation (vs. walking without aid) among THA (adjusted odds ratio (OR) 3.10, 95% confidence interval (95% CI) 1.26-7.57; p = 0.014) and TKA patients (OR 5.40, 95% CI 2.12-13.67; p < 0.001), and with requiring two crutches to walk or being unable to walk (vs. walking unaided or with one crutch) among PHA patients (OR 3.05, 95% CI 1.01-9.20; p = 0.047).

CONCLUSIONS

Ambulatory outcome in patients with hip and knee prostheses with postoperative PJI is worse than in patients who do not have PJI.

Clostridioides difficile carriage in animals and the associated changes in the host fecal microbiota

The relationship between the gut microbiota and Clostridioides difficile, and its role in the severity of C. difficile infection in humans is an area of active research. Intestinal carriage of toxigenic and non-toxigenic C. difficile strains, with and without clinical signs, is reported in animals, however few studies have looked at the risk factors associated with C. difficile carriage and the role of the host gut microbiota. Here, we isolated and characterized C. difficile strains from different animal species (predominantly canines (dogs), felines (cats), and equines (horses)) that were brought in for tertiary care at North Carolina State University Veterinary Hospital. C. difficile strains were characterized by toxin gene profiling, fluorescent PCR ribotyping, and antimicrobial susceptibility testing. 16S rRNA gene sequencing was done on animal feces to investigate the relationship between the presence of C. difficile and the gut microbiota in different hosts. Here, we show that C. difficile was recovered from 20.9% of samples (42/201), which included 33 canines, 2 felines, and 7 equines. Over 69% (29/42) of the isolates were toxigenic and belonged to 14 different ribotypes including ones known to cause CDI in humans. The presence of C. difficile results in a shift in the fecal microbial community structure in both canines and equines. Commensal Clostridium hiranonis was negatively associated with C. difficile in canines. Further experimentation showed a clear antagonistic relationship between the two strains in vitro, suggesting that commensal Clostridia might play a role in colonization resistance against C. difficile in different hosts.

Sex differences in patients with ischemia and no obstructive coronary disease subjected to intracoronary acetylcholine test in a multicenter registry

Background

Ischemia with no obstructive coronary disease (INOCA) is increasingly diagnosed because of wide performance of coronary angiography. Prevalence of INOCA is higher in women than in men, however the exact pathophysiological mechanisms which may explain this phenomenon are still not very well understood.

Objective

To evaluate differences in clinical and procedural characteristics between men and women with INOCA subjected to intracoronary acetylcholine test (Ach).

Methods

A total of 210 women and 148 men with INOCA diagnosed with coronary angiography, were prospectively enrolled in a multicenter, observational registry. Ach test was performed according to clinical indications in all included patients. After 1-year patients were re-evaluated for major cardiovascular events, angina symptoms and prescribed medical treatment.

Results

Mean age of 60.6±13.6 years old was similar in both populations, but differences were observed in the prevalence of risk factors: active smoking was more frequent among men (43% vs. 17%, p&lt;0.001), who had also a higher number of associated risk factors (≥3 risk factors were present in 31.2% of men vs. 20.2% of women, p&lt;0.01) and more frequent history of percutaneous coronary revascularization (14.2% vs. 6.7%, p=0.03). Women were more prone to have dyspnea than men (35.5% vs. 20.8%, p=0.01). Men had more coronary atherosclerosis in angiography (57.9% vs. 43.7%, p=0.01) and more slow flow in the left anterior descending artery (21.6% vs. 9.0%, p=0.001). Ach was positive in 36.5% of patients, similar in both sexes, with no differences in the type of induced coronary spasm. Among those with a positive Ach test, at one-year, 36% of women vs. 43.6% of men were on optimal medical treatment for vasospasm although the difference was not statistically significant. Importantly, 41.5% of women and 38.1% of men experienced severe symptoms of angina during follow-up.

Conclusions

Although men with INOCA have a higher risk profile than women and more coronary atherosclerosis, one third of patients present endothelial dysfunction, similar in both groups, indicating that probably other pathophysiological mechanisms are responsible for it in females. Treatment in these patients remains suboptimal and associated with highly impaired quality of life.

Funding Acknowledgement

Type of funding source: None

Clinical profile and predictors of positivity of acetylcholine test in patients with angina and no obstructive coronary artery disease. Results of a multi-center mediterranean registry

Background

Coronary endothelial dysfunction and vasospasm are potential causes of ischemia in no obstructive coronary disease (INOCA) and are now known to be associated with an increased risk of major cardiovascular events (MACE) and impaired quality of life. The recent guidelines recommend the use of intracoronary acetylcholine to unravel the underlying pathophysiology of INOCA, by identifying those with endothelial dysfunction, and to guide future treatment in these patients.

Objective

To evaluate the clinical profile and prevalence of endothelial dysfunction in patients with INOCA, and to identify the predictors of positivity of the acetylcholine test.

Methods

A total of 358 patients with INOCA were prospectively enrolled in a multicenter observational study. Coronary angiography and acetylcholine test were performed according to clinical indications in all included patients. Patients were followed-up for 1-year for MACE and clinical reevaluation of symptoms.

Results

Patients' mean age was 60.6±13.5 y.o. and 58.7% were females, with no previous history of coronary heart disease in 76% of cases. Regarding clinical presentation, 56.9% had angina at rest, 59.9% exertional angina, and 29.5% dyspnea. In 39% the EKG was abnormal, and in 10.9% there was a troponin rise.

Coronary endothelial dysfunction –defined as a vasoconstriction over 30%– was observed in 129 (36%) patients, and severe vasoconstriction (&gt;70%) in 75 (21%). Of positive cases, 47 (36%) focal vasoconstriction, and 90 (70%) diffuse. On follow-up, patients with a positive Ach test were treated differently, with a lower prescription of betablockers (12% vs. 24%, p=0.01) and a higher use of vasodilators (47% vs. 28.5%, p=0.001). Guidelines-recommended optimal treatment was prescribed to 39.2% of patients with a positive acetylcholine test. Patients with positive acetylcholine test were more prone to having worsening angina (25.6% vs. 12.8%, p&lt;0.01) and minimal exertion angina (40% vs. 26.7%, p=0.03) on follow-up. Multivariable regression analysis showed that acetylcholine test positivity was predicted by the presence of diabetes (OR 1.7, p=0.04), exertional angina (OR 1.2, p=0.04), coronary atherosclerosis (OR 1.8, p=0.02) and coronary milking (OR 2.6, p=0.04).

Conclusions

Endothelial dysfunction detected by acetylcholine test was present in one third of patients with INOCA and was associated with more severe and worsening symptoms. Although Ach test positivity influenced the pharmacological treatment at discharge, a large room for optimization still remained.

Funding Acknowledgement

Type of funding source: None

AB0472 INFECTIOUS PROFILE IN PATIENTS WITH ANCA-ASSOCIATED VASCULITIS: RETROSPECTIVE ANALYSIS IN A REFERRAL CENTRE

Background:

The antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) are rare multisystem autoimmune diseases of unknown cause, characterised by inflammatory cell infiltration causing necrosis of blood vessels. The treatment of AAV requires prolonged immunosuppressive therapy. Infections remain a major cause of morbidity and mortality.

Objectives:

The aim of our study was to investigate the prevalence and characteristics of infection, and analyse the factors associated with infection in patients with AAV from Northern of Spain.

Methods:

Retrospective, descriptive study of patients with AAV followed in a specific Systemic Autoimmune Diseases and Thrombosis Unit from January 2000 to December 2019. Demographic, laboratory, microbiology, treatment and clinical data were collected from the medical records. AAV was diagnosed according to the definitions of the Chapel Hill nomenclature and designated as granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA), microscopic polyangiitis (MPA) or pauci-immune necrotizing and/or crescentic glomerulonephritis without systemic vasculitis (renal-limited vasculitis, RLV). Disease activity of AAV was evaluated by Birmingham Vasculitis Activity score (BVAS). The infection episode was considered on the basis of clinical, laboratory, microbiology, radiology information, and response to therapy. Different episodes of infection in one patient were independently reflected. Data were analysed using SPSS 25.0

Results:

Thirty-six patients of which 20 (55.6%) were males. Median follow-up was 42 months. The mean age at the diagnosis was 61.14 ± 17.49 years and mean BVAS was 18.81 ± 5.96. 15 patients were diagnosed of GPA, 13 of MPA, 5 of EGPA and 3 of RLV. 72.2% MPO, 11.1% PR3. Lung involvement occurred in 75% of patients, upper airways was detected in 41.7%, skin involvement in 16.7%, Nervous system affectation occurred in 33.3%. 30 patients (83.3%) had renal affectation with a mean of 1.93± 1.66 gr/dl of Proteinuria and 2.9±2.17mg/dl of creatinine. We detected hypocomplementemia in 27.8% of patients (C3 in 19.4% and C4 in 16.7%). Regarding induction treatments, all patients received corticoids at high doses, 21 (58.3%) Cyclophosphamide, 3 (20%) Rituximab and 2 (13.3%) patients, Azathioprine. When we analyse infections, we detected 15 patients (41.66%) who presented any infection after the diagnosis of AAV, with a total of 71 episodes of infection. The most frequent were bacterial infections (29 episodes), specifically gram negative pathogens. The most frequent location was the respiratory (56.3%) followed by urinary (22.5%) and Skin (8.5%). Also opportunistic infections were described: 3 patients with Aspergillus fumigatus and one patient with Cryptococcus neoformans. 41 of these episodes needed hospitalisation with a median stay of 11 days. 6 episodes warranted intensive care unit (ICU) admission. Infection related mortality was 2.82%. We made latent tuberculosis screening and Pneumocystis prophylaxis in all our patients. No cases of Tuberculosis or Pneumocystis were recorded. Factors associated with increased risk of hospitalisation with statistical signification in univariated study were MPA, Hypocomplementemia and increased BVAS. But in the logistical regression study, only the value of the BVAS maintained statistical significance. The only factor associated with elevated risk of ICU admission was IgG deficit in the multivariate analysis. Neither immunosuppressive therapy nor age was associated with increased risk of infection in our study.

Conclusion:

More than 50% of the episodes of infection needed hospitalisation in patients with AAV. Risk factors for hospitalisation and ICU admission were BVAS and IgG deficit respectively. Bacterial infections were the most frequent but fungal infections were the most severe.

Disclosure of Interests:

None declared

Ceftazidime, Carbapenems, or Piperacillin-tazobactam as Single Definitive Therapy for Pseudomonas aeruginosa Bloodstream Infection: A Multisite Retrospective Study

BACKGROUND

The optimal antibiotic regimen for Pseudomonas aeruginosa bacteremia is controversial. Although β-lactam monotherapy is common, data to guide the choice between antibiotics are scarce. We aimed to compare ceftazidime, carbapenems, and piperacillin-tazobactam as definitive monotherapy.

METHODS

A multinational retrospective study (9 countries, 25 centers) including 767 hospitalized patients with P. aeruginosa bacteremia treated with β-lactam monotherapy during 2009-2015. The primary outcome was 30-day all-cause mortality. Univariate and multivariate, including propensity-adjusted, analyses were conducted introducing monotherapy type as an independent variable.

RESULTS

Thirty-day mortality was 37/213 (17.4%), 42/210 (20%), and 55/344 (16%) in the ceftazidime, carbapenem, and piperacillin-tazobactam groups, respectively. Type of monotherapy was not significantly associated with mortality in either univariate, multivariate, or propensity-adjusted analyses (odds ratio [OR], 1.14; 95% confidence interval [CI], 0.52-2.46, for ceftazidime; OR, 1.3; 95% CI, 0.67-2.51, for piperacillin-tazobactam, with carbapenems as reference in propensity adjusted multivariate analysis; 542 patients). No significant difference between antibiotics was demonstrated for clinical failure, microbiological failure, or adverse events. Isolation of P. aeruginosa with new resistance to antipseudomonal drugs was significantly more frequent with carbapenems (36/206 [17.5%]) versus ceftazidime (25/201 [12.4%]) and piperacillin-tazobactam (28/332 [8.4%] (P = .007).

CONCLUSIONS

No significant difference in mortality, clinical, and microbiological outcomes or adverse events was demonstrated between ceftazidime, carbapenems, and piperacillin-tazobactam as definitive treatment of P. aeruginosa bacteremia. Higher rates of resistant P. aeruginosa after patients were treated with carbapenems, along with the general preference for carbapenem-sparing regimens, suggests using ceftazidime or piperacillin-tazobactam for treating susceptible infection.

Pathogenesis of Staphylococcus epidermidis in prosthetic joint infections: Can identification of virulence genes differentiate between infecting and commensal strains?

BACKGROUND

Staphylococcus epidermidis is a commensal of human skin flora and a frequent causative microorganism in prosthetic joint infections (PJIs). To date, no single marker has been identified to distinguish infecting strains from commensal S. epidermidis populations.

AIM

We aimed to find possible genetic markers to distinguish between the two populations.

METHODS

We analyzed 50 S. epidermidis strains from patients with PJIs, 50 from skin of healthy individuals (commensal strains) and 17 from the surgical field of patients undergoing primary arthroplasty. In these three groups we studied the antimicrobial susceptibility profile, sequence type, biofilm formation, and virulence factors. Strains from the surgical field have not been compared previously with strains from the other two groups.

FINDINGS

S. epidermidis strains from PJI patients were significantly more antibiotic resistant than commensal strains and surgical field strains. A wide variety of sequences types was found in commensal and surgical field strains. The predominant sequence type was ST2 and it was only present in PJI strains (44%). Differences in biofilm production did not differ between populations. Virulence genes sdrF and bhp, the complete ica operon, and the insertion sequence IS256 were significantly predominant in PJI strains. In contrast, embp and hld genes and the mobile element ACME were more prevalent in commensal strains. Surgical field strains could be a valid control group to discriminate between infecting and commensal strains.

CONCLUSION

A combination of characteristic features can differentiate between infecting and commensal S. epidermidis strains in PJI, while a single marker cannot.

Risk factors for mortality among patients with Pseudomonas aeruginosa bacteraemia: a retrospective multicentre study

This study aimed to evaluate risk factors for 30-day mortality among hospitalised patients with Pseudomonas aeruginosa bacteraemia, a highly fatal condition. A retrospective study was conducted between 1 January 2009 and 31 October 2015 in 25 centres (9 countries) including 2396 patients. Univariable and multivariable analyses of risk factors were conducted for the entire cohort and for patients surviving ≥48 h. A propensity score for predictors of appropriate empirical therapy was introduced into the analysis. Of the 2396 patients, 636 (26.5%) died within 30 days. Significant predictors (odds ratio and 95% confidence interval) of mortality in the multivariable analysis included patient-related factors: age (1.02, 1.01-1.03); female sex (1.34, 1.03-1.77); bedridden functional capacity (1.99, 1.24-3.21); recent hospitalisation (1.43, 1.07-1.92); concomitant corticosteroids (1.33, 1.02-1.73); and Charlson comorbidity index (1.05, 1.01-1.93). Infection-related factors were multidrug-resistant Pseudomonas (1.52, 1.15-2.1), non-urinary source (2.44, 1.54-3.85) and Sequential Organ Failure Assessment (SOFA) score (1.27, 1.18-1.36). Inappropriate empirical therapy was not associated with increased mortality (0.81, 0.49-1.33). Among 2135 patients surviving ≥48 h, hospital-acquired infection (1.59, 1.21-2.09), baseline endotracheal tube (1.63, 1.13-2.36) and ICU admission (1.53, 1.02-2.28) were additional risk factors. Risk factors for mortality among patients with P. aeruginosa were mostly irreversible. Early appropriate empirical therapy was not associated with reduced mortality. Further research should be conducted to explore subgroups that may not benefit from broad-spectrum antipseudomonal empirical therapy. Efforts should focus on prevention of infection, mainly hospital-acquired infection and multidrug-resistant pseudomonal infection.

Trends of maxillofacial trauma: An update from the prospective register of a multicenter study in emergency services of Chile

Background

Determine the behavior of the maxillofacial trauma of adults treated in 3 tertiary care centers in the central zone of Chile.

Material and Methods

Descriptive, cross-sectional, multicenter study, based on the prospective records of maxillofacial trauma cases attended between May 2016 and April 2017 by dental and maxillofacial clinical teams of Adult Emergency Units of hospitals Dr. Sótero del Río (metropolitan region), Carlos Van Buren and Dr. Gustavo Fricke (region V). Age, sex, date of occurrence, type of trauma according to ICD-10, etiology, legal medical prognosis and associated injuries were recorded, stratifying by sex and age. Chi square and unpaired Wilcoxon tests were used to compare by groups.

Results

2.485 cases and 3.285 injuries were investigated. The male: female ratio was 1.7: 1 with age under 30 predominant, followed by older adults. Variability was observed in the yearly, weekly and daily presentation. The highest frequencies were in January and September, weekends and at night. The main etiologies were violence (42.3%), falls (13.1%) and road traffic crashes (12.9%) with differences by age and sex (p<0.05). 31,9% of the injuries occurred in hard tissue, being fractures in nasal bones predominant (S02.2).

Conclusions

The profile of the maxillofacial trauma in Chile seems to be mixed by age, affecting young people and the elderly. The male sex predominates; the main cause, which varies by age group, is violence. Their surveillance is possible from hospital emergency records.

Key words:Maxillofacial trauma, emergency department, multicenter study.

Association between Pseudomonas aeruginosa O-antigen serotypes, resistance profiles and high-risk clones: results from a Spanish nationwide survey

Objectives

To evaluate the correlation of O-antigen serotypes with resistance profiles and high-risk clones in a Spanish nationwide survey.

Methods

Up to 30 consecutive healthcare-associated Pseudomonas aeruginosa isolates were collected during October 2017 from each of 51 hospitals (covering all Spanish regions) with a total of 1445 isolates studied. MICs of 13 antipseudomonal agents and MDR/XDR profiles had been previously determined, as well as whole-genome sequences of 185 representative XDR isolates. O-antigen serotypes (O1–O16) were determined by agglutination using serotype-specific antisera (BioRad). The Pseudomonas aeruginosa serotyper (PAst) program was used for in silico serotyping.

Results

The most frequent serotypes were O6 (17.8%), O1 (15.4%) and O11 (13.3%). In contrast, the most frequent serotype among XDR isolates (17.3%) was O4 (34.1%), distantly followed by O11 (15.9%). Within serotypes, XDR phenotypes were more frequent for O12 (60.0%) and O4 (57.3%). The most frequent clone among the XDR isolates was ST175 (40.9%), followed by CC235 (10.7%), ST308 (5.2%) and CC111 (3.6%). Up to 81.6% of XDR ST175 isolates typed O4, whereas 18.4% were non-typeable. O4 genotype was detected in all sequenced (n=55) ST175 isolates. On the other hand, CC235 and ST308 were associated with O11, whereas CC111 was linked to serotype O12.

Conclusions

O4 serotype is linked to the MDR/XDR profile of widespread ST175 (typically only susceptible to colistin, amikacin and the novel combinations ceftolozane/tazobactam and ceftazidime/avibactam) and therefore, after local validation, its detection in the microbiology laboratory might be useful for guiding semi-empirical antipseudomonal therapies and infection control measures in Spanish hospitals.

Colistin plus meropenem combination is synergistic in vitro against extensively drug-resistant Pseudomonas aeruginosa, including high-risk clones

BACKGROUND

Extensively drug-resistant (XDR) Pseudomonas aeruginosa (P. aeruginosa) and particularly P. aeruginosa high-risk clones, are of growing concern because treatment options are limited. For years, colistin monotherapy has been the only available treatment, but is well known that is not an optimal treatment. A combination of colistin with another antibiotic could be a possible therapeutic option.

OBJECTIVES

This study aimed to investigate effective antibiotic combinations against 20 XDR P. aeruginosa isolates obtained in a Spanish multicentre study (2015).

METHODS

Forty-five checkerboards with six antipseudomonal antibiotics (amikacin, aztreonam, ceftazidime, meropenem, colistin, and ceftolozane/tazobactam) were performed to determine whether combinations were synergic or additive by fractional inhibitory concentration indices. On average, 15 different regimens were evaluated in duplicate against the three most prevalent high-risk clones (ST175, ST235, ST111) by time-kill analyses over 24h. The combination showing synergism in the three high-risk clones was validated in all studied XDR isolates.

RESULTS

In time-kill curves, the untreated control failed, as did each study regimen when administered alone. Two combinations were synergistic in the three high-risk clones that were initially studied: amikacin plus ceftazidime and colistin plus meropenem, with the second being the most effective combination. The efficacy of colistin plus meropenem was then tested in all 20 isolates. A synergistic bacterial density reduction for the duration of the study occurred in 80% of the entire XDR collection.

CONCLUSIONS

These data suggest that colistin plus meropenem may be a useful combination for the treatment of infections due to XDR P. aeruginosa, including high-risk clones, which warrants evaluation in a clinical trial.

RNASEH1 gene variants are associated with autoimmune type 1 diabetes in Colombia

BACKGROUND

In a previous work, we found linkage and association of type 1 diabetes (T1D) to a 12 known gene region at chromosome 2p25 in Colombian families. Here, we present further work on this candidate region.

MATERIALS AND METHODS

Seventeen SNPs located on the 12 candidate genes, in 100 familial trios set, were tested by ARMS-tetraprimer-PCR or PCR-RFLP. Five extra SNPs in the vicinity of rs10186193 were typed. A replica phase included 97 novel familial trios, in whom diabetes-related auto-antibodies (AABs) were tested in sera of the patients. In addition to transmission disequilibrium tests, haplotype analyses were carried out using the unphased software.

RESULTS

SNP rs10186193 (at RNASEH1 gene) showed association with T1D (P = 0.005). The additional five SNPs revealed that rs7607888 (P = 2.03 × 10^-7), rs55981318 (P = 0.018), and rs1136545 (P = 1.93 × 10^-9) were also associated with T1D. Haplotype analysis showed association for rs55981318-rs10186193 (P = 0.0005), rs7563960-rs7607888 (P = 0.0007), rs7607888-rs1136545 (P = 9.21 × 10^-10), and rs1136545-rs11538545 (P = 6.67 × 10^-8). In contrast, the new set of 97 familial trios tested for SNPs rs55981318, rs10186193, and rs7607888 did not support the previous finding; however, by combining the sample (197 trios), evidence of association of T1D with rs55981318 and rs7607888 was conclusive. In addition, a two-loci haplotype analysis of the combined sample showed significant association of RNASEH1 with T1D (P = 3.1 × 10^-5).

CONCLUSION

In conclusion, our analyses suggest that RNASEH1 gene variants associate with susceptibility/protection to T1D in Colombia.

"It Ruined My Life": The effects of the War on Drugs on people who inject drugs (PWID) in rural Puerto Rico

BACKGROUND

The War on Drugs has raised the incarceration rates of racial minorities for non-violent drug-related crimes, profoundly stigmatized drug users, and redirected resources from drug prevention and treatment to militarizing federal and local law enforcement. Yet, while some states consider shifting their punitive approach to drug use, to one based on drug treatment and rehabilitation, nothing suggests that these policy shifts are being replicated in Puerto Rico.

METHODS

This paper utilizes data from 360 PWID residing in four rural towns in the mountainous area of central Puerto Rico. We initially recruited 315 PWID using respondent-driven sampling (RDS) and collected data about risk practices and conducted HIV and HCV testing. During a second phase, we conducted 34 micro-ethnographic assays, in which we randomly recruited 34 participants from the first phase and included their ego networks in this phase. Our ethnographic inquiry produced significant data regarding the effects of the war on drugs on the local drug trade, drug availability, and injectors' social networks.

RESULTS

Findings suggest that repressive policing has been ineffective in preventing drug distribution and use among those in our study. This type of law enforcement approach has resulted in the disproportionate incarceration of poor drug users in rural Puerto Rico, and mainly for nonviolent drug-related crimes. In addition, incarceration exposes PWID to a form of a cruel and unusual punishment: having to quit heroin "cold turkey" while the prison environment also represents a HIV/HCV risk. In turn, the war on drugs not only diverts resources from treatment but also shapes treatment ideologies, punishing non-compliant patients.

CONCLUSION

Shifting the emphasis from repression to treatment and rehabilitation is likely to have a positive impact on the health and overall quality of life of PWID and their communities.

Genomics and Susceptibility Profiles of Extensively Drug-Resistant Pseudomonas aeruginosa Isolates from Spain

This study assessed the molecular epidemiology, resistance mechanisms, and susceptibility profiles of a collection of 150 extensively drug-resistant (XDR) Pseudomonas aeruginosa clinical isolates obtained from a 2015 Spanish multicenter study, with a particular focus on resistome analysis in relation to ceftolozane-tazobactam susceptibility. Broth microdilution MICs revealed that nearly all (>95%) of the isolates were nonsusceptible to piperacillin-tazobactam, ceftazidime, cefepime, aztreonam, imipenem, meropenem, and ciprofloxacin. Most of them were also resistant to tobramycin (77%), whereas nonsusceptibility rates were lower for ceftolozane-tazobactam (31%), amikacin (7%), and colistin (2%). Pulsed-field gel electrophoresis-multilocus sequence typing (PFGE-MLST) analysis revealed that nearly all of the isolates belonged to previously described high-risk clones. Sequence type 175 (ST175) was detected in all 9 participating hospitals and accounted for 68% (n = 101) of the XDR isolates, distantly followed by ST244 (n = 16), ST253 (n = 12), ST235 (n = 8), and ST111 (n = 2), which were detected only in 1 to 2 hospitals. Through phenotypic and molecular methods, the presence of horizontally acquired carbapenemases was detected in 21% of the isolates, mostly VIM (17%) and GES enzymes (4%). At least two representative isolates from each clone and hospital (n = 44) were fully sequenced on an Illumina MiSeq. Classical mutational mechanisms, such as those leading to the overexpression of the β-lactamase AmpC or efflux pumps, OprD inactivation, and/or quinolone resistance-determining regions (QRDR) mutations, were confirmed in most isolates and correlated well with the resistance phenotypes in the absence of horizontally acquired determinants. Ceftolozane-tazobactam resistance was not detected in carbapenemase-negative isolates, in agreement with sequencing data showing the absence of ampC mutations. The unique set of mutations responsible for the XDR phenotype of ST175 clone documented 7 years earlier were found to be conserved, denoting the long-term persistence of this specific XDR lineage in Spanish hospitals. Finally, other potentially relevant mutations were evidenced, including those in penicillin-binding protein 3 (PBP3), which is involved in β-lactam (including ceftolozane-tazobactam) resistance, and FusA1, which is linked to aminoglycoside resistance.