ß-lactamase expression induces collateral sensitivity in Escherichia coli.

Major antibiotic groups are losing effectiveness due to the uncontrollable spread of antimicrobial resistance (AMR) genes. Among these, ß-lactam resistance genes -encoding ß-lactamases- stand as the most common resistance mechanism in Enterobacterales due to their frequent association with mobile genetic elements. In this context, novel approaches that counter mobile AMR are urgently needed. Collateral sensitivity (CS) occurs when the acquisition of resistance to one antibiotic increases susceptibility to another antibiotic and can be exploited to eliminate AMR selectively. However, most CS networks described so far emerge as a consequence of chromosomal mutations and cannot be leveraged to tackle mobile AMR. Here, we dissect the CS response elicited by the acquisition of a prevalent antibiotic resistance plasmid to reveal that the expression of the ß-lactamase gene blaOXA-48 induces CS to colistin and azithromycin. We next show that other clinically relevant mobile ß-lactamases produce similar CS responses in multiple, phylogenetically unrelated E. coli strains. Finally, by combining experiments with surveillance data comprising thousands of antibiotic susceptibility tests, we show that ß-lactamase-induced CS is pervasive within Enterobacterales. These results highlight that the physiological side-effects of ß-lactamases can be leveraged therapeutically, paving the way for the rational design of specific therapies to block mobile AMR or at least counteract their effects.

The role of bacterial metabolism in human gut colonization.

Can we anticipate the emergence of the next pandemic antibiotic-resistant bacterial clone? Addressing such an ambitious question relies on our ability to comprehensively understand the ecological and epidemiological factors fostering the evolution of high-risk clones. Among these factors, the ability to persistently colonize and thrive in the human gut is crucial for most high-risk clones. Nonetheless, the causes and mechanisms facilitating successful gut colonization remain obscure. Here, we review recent evidence that suggests that bacterial metabolism plays a pivotal role in determining the ability of high-risk clones to colonize the human gut. Subsequently, we outline novel approaches that enable the exploration of microbial metabolism at an unprecedented scale and level of detail. A thorough understanding of the constraints and opportunities of bacterial metabolism in gut colonization will foster our ability to predict the emergence of high-risk clones and take appropriate containment strategies.

Case Report: Ambergris coprolite and septicemia in a male sperm whale stranded in La Palma (Canary Islands).

On the 21st of May 2023, a dead adult male sperm whale (Physeter macrocephalus) of 13 m in length and estimated weight of around 18,000 kg was reportedly stranded at Playa Los Nogales, La Palma, Canary Islands, Spain. A necropsy was performed 48hpm. A 50 cm diameter and 9.5 kg coprolite was found obstructing the caudal colon-rectal lumen. Necro-hemorrhagic lesions were found in heart muscles and three different bacteria of intestinal origin were isolated and identified (Edwarsiella tarda, Hathewaya limosa and Clostridium perfringens). It is reported a lethal septicemia of intestinal origin associated with ambergris coprolite as cause of death in this sperm whale.

Enterobacterales carrying chromosomal AmpC ß-lactamases in Europe (EuESCPM): Epidemiology and antimicrobial resistance burden from a cohort of 27 hospitals, 2020-2022.

INTRODUCTION: The ESCPM group (Enterobacter species including Klebsiella aerogenes - formerly Enterobacter aerogenes, Serratia species, Citrobacter freundii complex, Providencia species and Morganella morganii) has not yet been incorporated into systematic surveillance programs. METHODS: We conducted a multicentre retrospective observational study analysing all ESCPM strains isolated from blood cultures in 27 European hospitals over a 3-year period (2020-2022). Diagnostic approach, epidemiology, and antimicrobial susceptibility were investigated. RESULTS: Our study comprised 6,774 ESCPM isolates. MALDI-TOF coupled to mass spectrometry was the predominant technique for bacterial identification. Susceptibility to new ß-lactam/ß-lactamase inhibitor combinations and confirmation of AmpC overproduction were routinely tested in 33.3% and 29.6% of the centres, respectively. The most prevalent species were E. cloacae complex (44.8%) and S. marcescens (22.7%). Overall, third-generation cephalosporins (3GC), combined third- and fourth-generation cephalosporins (3GC + 4GC) and carbapenems resistance phenotypes were observed in 15.7%, 4.6%, and 9.5% of the isolates, respectively. AmpC overproduction was the most prevalent resistance mechanism detected (15.8%). Among carbapenemase-producers, carbapenemase type was provided in 44.4% of the isolates, VIM- (22.9%) and OXA-48-enzyme (16%) being the most frequently detected. E. cloacae complex, K. aerogenes and Providencia species exhibited the most notable cumulative antimicrobial resistance profiles, with the former displaying 3GC, combined 3GC + 4GC and carbapenems resistance phenotypes in 15.2%, 7.4%, and 12.8% of the isolates, respectively. K. aerogenes showed the highest rate of both 3GC resistant phenotype (29.8%) and AmpC overproduction (32.1%), while Providencia species those of both carbapenems resistance phenotype (42.7%) and carbapenemase production (29.4%). ESCPM isolates exhibiting both 3GC and combined 3GC + 4GC resistance phenotypes displayed high susceptibility to ceftazidime/avibactam (98.2% and 95.7%, respectively) and colistin (90.3% and 90.7%, respectively). Colistin emerged as the most active drug against ESCPM species (except those intrinsically resistant) displaying both carbapenems resistance phenotype (85.8%) and carbapenemase production (97.8%). CONCLUSIONS: This study presented a current analysis of ESCPM species epidemiology in Europe, providing insights to inform current antibiotic treatments and guide strategies for antimicrobial stewardship and diagnostics.

Feasibility and outcomes after dose reduction of immunochemotherapy in young adults with Burkitt lymphoma and leukemia: results of the BURKIMAB14 trial.

High dose-intensive or infusional intermediate-dose immunochemotherapy is highly effective treatment for Burkitt lymphoma irrespective of human immunodeficiency virus (HIV) infection. However, toxicities of these regimens are relevant, especially in older adults and elderly patients. The prospective multicenter BURKIMAB14 trial included four to six blocks of immunochemotherapy according to stage (localized: 1 and 2 non-bulky; advanced: 2 bulky, 3, 4) and age, with dose reduction in patients >55 years old. Dose-intensity of chemotherapy was reduced in patients ≤55 years old after achieving complete metabolic response (CMR). Their outcomes were compared with those of similar patients included in the former BURKIMAB08 trial, in which there was no dose reduction. CMR was attained in 86 of 107 (80%) patients (17/19 in localized stages and 69/88 in advanced stages). Patients from the BURKIMAB14 trial ≤55 years old showed similar overall survival (OS), fewer infections and cytopenias than patients from the BURKIMAB08 trial. Patients >55 years old had a significantly higher treatment- related mortality despite dose reduction of chemotherapy. With a median follow-up of 3.61 years the 4-year OS probability was 73% (range, 63-81%). Age (≤55 vs. >55 years) and stage (localized vs. advanced) had prognostic significance. No significant differences in OS were observed in HIV-positive versus HIV-negative patients. The results of BURKIMAB14 are similar to those of other dose-intensive immunochemotherapy trials. Age >55 years and advanced stage, but not HIV infection, were associated with poor survival. Dose reduction of chemotherapy in young adults in CMR is safe and does not impact outcomes (clinicaltrials gov. Identifier: NCT05049473).

Real-World Outcomes of Belantamab Mafodotin for Relapsed/Refractory Multiple Myeloma (RRMM): Preliminary Results of a Spanish Expanded Access Program (EAP).

INTRODUCTION: Belantamab mafodotin (BM) is a new anti-BCMA antibody-drug conjugate, recently approved for triple-class relapsed and refractory multiple myeloma (RRMM). We assessed real-world outcomes with BM in patients under the Spanish Expanded Access Program (EAP). METHODS: We conducted an observational, retrospective, multicenter study including RRMM patients who received ≥ 1 dose of BM (Nov 2019 to Jun 2021). The primary endpoint was overall response rate (ORR). Secondary endpoints were progression-free survival (PFS), overall survival (OS), and incidence of treatment-emergent adverse events (TEAEs). RESULTS: Thirty-three patients were included with a median of 70 years of age (range, 46-79 years). Median time from diagnosis was 71 months (range, 10-858 months). Median prior lines was 5 (range, 3-8 lines); 90% of patients were triple-/quad-/penta-refractory; 48% showed high-risk cytogenetics. Median BM doses was 3 (range 1-16 doses), with a median follow-up of 11 months (6-15 months). ORR was 42.2% (≥ VGPR, 18.2%). Median PFS was 3 months (95% CI 0.92-5.08) in the overall population, and 11 months (HR 0.26; 95% CI 0.10-0.68) for patients who achieved ≥ PR. PFS was not significantly different according to age, cytogenetic risk, and prior therapy lines. OS was 424 days (95% CI 107-740). Non-hematological TEAEs (57.6% of patients; 30.3% ≥ G3) included keratopathy (51.5%; 21.2% ≥ G3) and patient-reported vision-related symptoms (45.5%). Keratopathy was resolved in 70.6% of patients. G3 hematological TEAEs was 18.2%, thrombocytopenia (21.2%). Dose reductions due to TEAEs: 30.3%; delays: 36.4%. Treatment discontinuation causes: progression (54.5%), toxicity (non-ocular; 6%/ocular; 6% /ocular + non-ocular toxicity; 3%), death (6%), and patient's decision (3%). CONCLUSIONS: BM showed relevant anti-myeloma activity in RRMM with a manageable safety profile. These results corroborate those observed in the BM pivotal trial.

Evaluating the drop test method in measuring colistin susceptibility of Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa.

Introduction. Colistin is an antibiotic used to treat Gram-negative bacterial infections, particularly those caused by multidrug-resistant bacteria.Hypothesis/Gap Statement. The broth microdilution (BMD) reference method is the recommended protocol for detecting colistin susceptibility; however, it is laborious and expensive and cannot be performed in all laboratories.Aim. To evaluate the colistin susceptibility in Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa using an alternative method, which has been referred to as the drop test.Methodology. A 16 µg ml-1 colistin solution was deposited on a Mueller-Hinton agar plate previously swabbed with the strain and incubated overnight, and the presence or absence of an inhibition zone was observed.Results. The categorical agreement (CA) of the drop test with respect to BMD was 100 % when 190 Enterobacterales (19 E. coli and 171 K. pneumoniae) were used, and no major errors (MEs) or very major errors (VMEs) were detected. The CA of the drop test with respect to the BMD was 99.2 % for 119 P. aeruginosa isolates, while no ME was detected and only 1 VME (6.7%) was observed.Conclusion. The drop test is an alternative method for antimicrobial susceptibility testing of colistin against K. pneumoniae and E. coli. It is an adequate method for detecting resistant strains of P. aeruginosa, but susceptible isolates should be confirmed using BMD. The drop test is a simpler alternative to the BMD that does not require additional equipment and allows for the testing of numerous isolates in a short period of time.

Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae in Fresh Produce.

Fresh vegetables are an essential part of a healthy diet, but microbial contamination of fruits and vegetables is a serious concern to human health, not only for the presence of foodborne pathogens but because they can be a vehicle for the transmission of antibiotic-resistant bacteria. This work aimed to investigate the importance of fresh produce in the transmission of extended-spectrum ß-lactamases (ESBL)-producing Enterobacteriaceae. A total of 174 samples of vegetables (117) and farm environment (57) were analysed to determine enterobacterial contamination and presence of ESBL-producing Enterobacteriaceae. Enterobacterial counts above the detection limit were found in 82.9% vegetable samples and 36.8% environmental samples. The average count was 4.2 log cfu/g or mL, with a maximum value of 6.2 log cfu/g in a parsley sample. Leafy vegetables showed statistically significant higher mean counts than other vegetables. A total of 15 ESBL-producing isolates were obtained from vegetables (14) and water (1) samples and were identified as Serratia fonticola (11) and Rahnella aquatilis (4). Five isolates of S. fonticola were considered multi-drug resistant. Even though their implication in human infections is rare, they can become an environmental reservoir of antibiotic-resistance genes that can be further disseminated along the food chain.

Outcomes and prognostic factors of adults with refractory or relapsed T-cell acute lymphoblastic leukemia included in measurable residual disease-oriented trials.

Despite high complete remission (CR) rates with frontline therapy, relapses are frequent in adults with T-cell acute lymphoblastic leukemia (T-ALL) with limited salvage options. We analyzed the outcomes and prognostic factors for CR to salvage therapy and overall survival (OS) of patients with R/R T-ALL included in two prospective measurable residual disease-oriented trials. Seventy-five patients (70 relapsed, 5 refractory) were identified. Relapses occurred in bone marrow, isolated or combined in 50 patients, and in the central nervous system (CNS; isolated or combined) in 20. Second CR was attained in 30/75 patients (40%). Treatment with FLAG-Ida and isolated CNS relapse were independently associated with a higher CR rate after first salvage therapy. The median OS was 6.2 (95% confidence interval [CI], 3.9-8.6) months, with a 4-year OS probability of 18% (95% CI, 9%-27%). No differences in survival were observed according to the treatment with hematopoietic stem cell transplantation in patients in CR after first salvage therapy. Multivariable analysis showed a ≥12-month interval between first CR and relapse, CR after first salvage therapy and isolated CNS relapse as favorable prognostic factors for OS with hazard ratios (HR) (95% CI) of 1.931 (1.109-3.362), 2.958 (1.640-5.334), and 2.976 (1.157-7.655), respectively. This study confirms the poor outcomes of adults with R/R T-ALL among whom FLAG-Ida was the best of the rescue therapies evaluated. Late relapse, CR after first rescue therapy and isolated CNS relapse showed prognostic impact on survival. More effective rescue therapies are needed in adults with R/R T-ALL.

Frequency, Clinical Characteristics and Outcome of Adults With Acute Lymphoblastic Leukemia and COVID 19 Infection in the First vs. Second Pandemic Wave in Spain.

BACKGROUND AND OBJECTIVE: SARS-CoV-2 infection has bimodal distribution in Europe with a first wave in March to June 2020 and a second in September 2020 to February 2021. We compared the frequency, clinical characteristics and outcomes of adults with acute lymphoblastic leukemia (ALL) and infection in the first vs. second pandemic waves in Spain. PATIENTS AND METHODS: In this prospective study the characteristics of ALL and COVID-19 infection, comorbidities, treatment and outcome in the two periods were compared. The study ended when vaccination against SARS-CoV-2 was implemented in Spain. RESULTS: Twenty eight patients were collected in the first wave and 24 in the second. The median age was 46.5 years (range 20-83). Patients from the first wave had a trend to more severe ALL (higher frequency of patients under induction or submitted to transplantation or under immunosuppressive therapy). No significant differences were observed in need for oxygen support, intensive care unit (ICU) requirement, days in ICU and time to COVID-19 infection recovery. Seventeen patients (33%) died, with death attributed to COVID infection in 15 (29%), without significant differences in the 100 day overall survival (OS) probabilities in the two waves (68% ± 17% vs. 56% ± 30%). The only prognostic factor for OS identified by was the presence of comorbidities at COVID-19 infection (HR: 5.358 [95% CI: 1.875- 15.313]). CONCLUSION: The frequency and mortality of COVID-19 infection were high in adults with ALL, without changes over time, providing evidence in favor of vaccination priority for these patients.

Coat color variation at the beginning of horse domestication.

The transformation of wild animals into domestic ones available for human nutrition was a key prerequisite for modern human societies. However, no other domestic species has had such a substantial impact on the warfare, transportation, and communication capabilities of human societies as the horse. Here, we show that the analysis of ancient DNA targeting nuclear genes responsible for coat coloration allows us to shed light on the timing and place of horse domestication. We conclude that it is unlikely that horse domestication substantially predates the occurrence of coat color variation, which was found to begin around the third millennium before the common era.