Effects of Losartan on Patients Hospitalized for Acute COVID-19: A Randomized Controlled Trial.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) down-regulates angiotensin-converting enzyme 2, potentially increasing angiotensin II. We hypothesized that losartan compared to usual care decreases mortality and is safe in patients hospitalized with coronavirus disease 2019 (COVID-19). We aimed to evaluate the effect of losartan versus usual care on 28-day mortality in patients hospitalized for acute COVID-19. METHODS: Eligibility criteria included adults admitted for acute COVID-19. Exclusion criteria were hypotension, hyperkalemia, acute kidney injury, and use of angiotensin receptor blockers (ARBs) or angiotensin-converting enzyme inhibitors within 7 days. Participants were randomized to losartan 25-100 mg/day orally for the hospital duration or 3 months or the control arm (usual care) in 29 hospitals in Canada and France. The primary outcome was 28-day mortality. Secondary outcomes were hospital mortality, organ support, and serious adverse events (SAEs). RESULTS: The trial was stopped early because of a serious safety concern with losartan. In 341 patients, any SAE and hypotension were significantly higher in the losartan versus usual care groups (any SAE: 39.8% vs 27.2%, respectively, P = .01; hypotension: 30.4% vs 15.3%, respectively, P < .001) in both ward and intensive care patients. The 28-day mortality did not differ between losartan (6.5%) versus usual care (5.9%) (odds ratio, 1.11 [95% confidence interval, .47-2.64]; P = .81), nor did organ dysfunction or secondary outcomes. CONCLUSIONS: Caution is needed in deciding which patients to start or continue using ARBs in patients hospitalized with pneumonia to mitigate risk of hypotension, acute kidney injury, and other side effects. ARBs should not be added to care of patients hospitalized for acute COVID-19. CLINICAL TRIALS REGISTRATION: NCT04606563.

Two cases of Francisella tularensis subspecies holartica prosthetic valve endocarditis, and review of the literature.

Francisella tularensis endocarditis is rare and difficult to diagnose, and only a few cases have been described. We report two new cases of endocarditis due to F. tularensis subsp. holarctica, with a favorable evolution after appropriate antibiotic therapy and valve replacement surgery, and review the 5 other cases reported in the literature. This rare infection may be suspected based on the local epidemiology and the patient's exposure factors. A regimen of ciprofloxacin and gentamicin, combined with surgical valve replacement if necessary, appears to be effective in treating F. tularensis endocarditis.

Changes in Inflammatory Markers in Patients Treated for Buruli Ulcer and Their Ability to Predict Paradoxical Reactions.

Mycobacterium ulcerans causes Buruli ulcer, the third most frequent mycobacterial disease after tuberculosis and leprosy. Transient clinical deteriorations, known as paradoxical reactions (PRs), occur in some patients during or after antibiotic treatment. We investigated the clinical and biological features of PRs in a prospective cohort of 41 patients with Buruli ulcer from Benin. Neutrophil counts decreased from baseline to day 90, and interleukin 6 (IL-6), granulocyte colony-stimulating factor, and vascular endothelial growth factor were the cytokines displaying a significant monthly decrease relative to baseline. PRs occurred in 10 (24%) patients. The baseline biological and clinical characteristics of the patients presenting with PRs did not differ significantly from those of the other patients. However, the patients with PRs had significantly higher IL-6 and tumor necrosis factor alpha (TNF-α) concentrations on days 30, 60, and 90 after the start of antibiotic treatment. The absence of a decrease in IL-6 and TNF-α levels during treatment should alert clinicians to the possibility of PR onset.

Impact of Enterococcus faecalis Endocarditis Treatment on Risk of Relapse.

BACKGROUND: Enterococcus faecalis infective endocarditis (EFIE) is characterized by a higher frequency of relapses than other infective endocarditis. The role of the treatment on its occurrence remains poorly understood. The aim of this study was to investigate whether the antibiotic regimen could impact the risk of relapse in EFIE. MATERIALS: This was a multicenter retrospective study of patients diagnosed with definite EFIE between 2015 and 2019 in 14 French hospitals. The primary endpoint was the occurrence of relapses within the year following endocarditis diagnosis. As death was a competing risk for relapse, Fine and Gray models were used for studying risk factors and impact of treatment. RESULTS: Of the 279 patients included, 83 (29.7%) received the amoxicillin-gentamicin (A-G) combination, 114 (40.9%) amoxicillin-ceftriaxone (A-C), 63 (22.6%) A-G and A-C (A-G/A-C) sequentially, 9 (3.2%) amoxicillin (A), and 10 received other treatments. One-year-relapse rate was 9.3% (26 patients). Relapse occurred after a median delay of 107 days from EFIE diagnosis; 6 occurred after 6 months, and 6 were diagnosed by blood cultures in asymptomatic patients. In multivariate analysis, surgery during treatment was a protective factor against one-year relapse and death.The cumulative incidence of relapse 1 year after endocarditis was 46.2% for patients treated with amoxicillin, 13.4% with A-G, 14.7% with A-C, and 4.3% with A-G/A-C (P≥.05 in multivariate analysis). CONCLUSIONS: Relapses after treatment of EFIE are frequent, frequently asymptomatic, and may occur more than 6 months after the initial episode.

Dalbavancin plasma concentrations in 133 patients: a PK/PD observational study.

OBJECTIVES: Limited pharmacokinetics data support dalbavancin long-term use in off-label indications and the optimal dosing regimen is debated. We aimed to describe dalbavancin concentrations in an observational retrospective multicentre study. METHODS: Patients from 13 French hospitals, treated with 1500 mg doses of dalbavancin and for whom therapeutic drug monitoring was performed from June 2018 to March 2021 were included. Dalbavancin plasma concentrations were described at peak and 1, 2, 3, 4, 6 and 8 weeks after the last 1500 mg dose. Concentrations in patients weighing more or less than 75 kg and with a GFR greater or less than 60 mL/min were compared. Microbiological data were collected and dalbavancin MIC was measured when possible. RESULTS: One hundred and thirty-three patients were included (69% treated for bone and joint infections, 16% for endocarditis). Thirty-five patients received a single dose of dalbavancin and 98 received several administrations. Two, 3 and 4 weeks after the last dose, median plasma concentrations were respectively 25.00, 14.80 and 9.24 mg/L for the first doses and 34.55, 22.60 and 19.20 mg/L for the second or subsequent doses. Weight and renal function had an impact on pharmacokinetics. Infection was documented in 105 patients (Staphylococcus spp. in 68% of cases). Staphylococcus aureus was isolated in 32.5% of cases (median MIC: 0.047 mg/L) and Staphylococcus epidermidis in 27% of cases (median MIC of 0.047 mg/L). CONCLUSIONS: Plasma concentrations of dalbavancin were consistent with those described in clinical trials and those sought during the industrial development of the molecule.

Infective endocarditis in pregnant women without intravenous drug use: a multicentre retrospective case series.

OBJECTIVES: To describe the clinical features and outcomes of infective endocarditis (IE) in pregnant women who do not inject drugs. METHODS: A multinational retrospective study was performed at 14 hospitals. All definite IE episodes between January 2000 and April 2021 were included. The main outcomes were maternal mortality and pregnancy-related complications. RESULTS: Twenty-five episodes of IE were included. Median age at IE diagnosis was 33.2 years (IQR 28.3-36.6) and median gestational age was 30 weeks (IQR 16-32). Thirteen (52%) patients had no previously known heart disease. Sixteen (64%) were native IE, 7 (28%) prosthetic and 2 (8%) cardiac implantable electronic device IE. The most common aetiologies were streptococci (n = 10, 40%), staphylococci (n = 5, 20%), HACEK group (n = 3, 12%) and Enterococcus faecalis (n = 3, 12%). Twenty (80%) patients presented at least one IE complication; the most common were heart failure (n = 13, 52%) and symptomatic embolism other than stroke (n = 4, 16%). Twenty-one (84%) patients had surgery indication and surgery was performed when indicated in 19 (90%). There was one maternal death and 16 (64%) patients presented pregnancy-related complications (11 patients ≥1 complication): 3 pregnancy losses, 9 urgent Caesarean sections, 2 emergency Caesarean sections, 1 fetal death, and 11 preterm births. Two patients presented a relapse during a median follow-up of 3.1 years (IQR 0.6-7.4). CONCLUSIONS: Strict medical surveillance of pregnant women with IE is required and must involve a multidisciplinary team including obstetricians and neonatologists. Furthermore, the potential risk of IE during pregnancy should never be underestimated in women with previously known underlying heart disease.

Association between COVID-19 infection and work exposure assessed by the Mat-O-Covid job exposure matrix in the CONSTANCES cohort.

OBJECTIVES: The COVID-19 pandemic has brought to light a new occupational health threat. We aimed to evaluate the association between COVID-19 infection and work exposure to SARS-CoV-2 assessed by a job-exposure matrix (JEM), in a large population cohort. We also estimated the population-attributable fraction among exposed subjects. METHODS: We used the SAPRIS-SERO sample of the CONSTANCES cohort, limited to subjects actively working, and with a job code available and a questionnaire on extra work activities. The following outcomes were assessed: COVID-19 diagnosis was made by a physician; a seropositivity to the ELISA-S test ('serology strict') and ELISA-S test intermediate with positive ELISA-NP or a positive neutralising antibodies SN ('serology large'). Job exposure was assessed using Mat-O-Covid, an expert-based JEM with an Index used as a continuous variable and a threshold at 13/1000. RESULTS: The sample included 18 999 subjects with 389 different jobs, 47.7% were men with a mean age of 46.2 years (±9.2 years). The Mat-O-Covid index taken as a continuous variable or with a threshold greater than 13/1000 was associated with all the outcomes in bivariable and multivariable logistic models. ORs were between 1.30 and 1.58, and proportion of COVID-19 attributable to work among exposed participants was between 20% and 40%. DISCUSSION: Using the Mat-O-Covid JEM applied to a large population, we found a significant association between work exposure to SARS-CoV-2 and COVID-19 infection, though the estimation of attributable fraction among exposed people remained low to moderate. Further studies during other exposed periods and with other methods are necessary.

Pharmacokinetics and Safety of XAV-19, a Swine Glyco-humanized Polyclonal Anti-SARS-CoV-2 Antibody, for COVID-19-Related Moderate Pneumonia: a Randomized, Double-Blind, Placebo-Controlled, Phase IIa Study.

We assessed the pharmacokinetics and safety of XAV-19, a swine glyco-humanized polyclonal antibody against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in coronavirus disease 2019 (COVID-19)-related moderate pneumonia. The objective was to evaluate the optimal dose and safety of XAV-19 during this first administration to patients with COVID-19-related moderate pneumonia. In this phase IIa trial, adults with COVID-19-related moderate pneumonia with a duration of ≤10 days were randomized to receive an infusion of XAV-19 at 0.5 mg/kg of body weight at day 1 and day 5 (group 1), 2 mg/kg at day 1 and day 5 (group 2), or 2 mg/kg at day 1 (group 3) or placebo. Eighteen patients (n = 7 for group 1, n = 1 for group 2, n = 5 for group 3, and n = 5 for placebo) were enrolled. Baseline characteristics were similar across groups; median XAV-19 serum concentrations (ranges) at the time of the maximum serum concentration of the drug (Cmax) and at day 8 were 9.1 (5.2 to 18.1) and 6.4 (2.8 to 11.9) µg/ml, 71.5 and 47.2 µg/ml, and 50.4 (29.1 to 55.0) and 20.3 (12.0 to 22.7) µg/ml for groups 1, 2, and 3, respectively (P = 0.012). The median terminal half-life (range) was estimated at 11.4 (5.5 to 13.9) days for 2 mg/kg of XAV-19 at day 1. Serum XAV-19 concentrations were above the target concentration of 10 µg/ml (2-fold the in vitro 100% inhibitory concentration [IC100]) from the end of perfusion to more than 8 days for XAV-19 at 2 mg/kg at day 1. No hypersensitivity or infusion-related reactions were reported during treatment, and there were no discontinuations for adverse events and no serious adverse events related to the study drug. A single intravenous dose of 2 mg/kg of XAV-19 demonstrated high serum concentrations, predictive of potent durable neutralizing activity with good tolerability. (This study has been registered at ClinicalTrials.gov under identifier NCT04453384.).

How and why do French medical students choose the specialty of infectious and tropical diseases? A national cross-sectional study.

BACKGROUND: Infectious and tropical diseases (ID) physicians are needed now more than ever to tackle existing and emerging global threats. However, in many countries, ID is not recognized as a qualifying specialty. The creation of ID residency in 2017 in France offers the opportunity to know how and why the specialty is chosen by medical students. METHODS: We first analyzed the choice of specialty of all French medical students in 2017 and 2018 according to their rank at the national exam that ends medical studies. A web questionnaire was then sent in January 2019 to all ID residents in France (n = 100) to assess the factors influencing their choice of specialty and their career plan. RESULTS: We analyzed the choice of 17,087 medical students. ID was the first-chosen specialty with a median national rank of 526/8539, followed by plastic surgery and ophthalmology. The questionnaire was completed by 90% of the French ID residents (n = 100). The most encouraging factors to choose ID were the multi-system approach of the specialty, the importance of diagnostic medicine and having done an internship in ID during medical school. The potential deterrents were the work-life balance, the workload and the salary. CONCLUSIONS: The recent recognition of ID as a qualifying specialty in France can be considered a success insofar as the specialty is the most popular among all medical and surgical specialties. Individuals who choose ID are attracted by the intellectual stimulation of the specialty but express concerns about the working conditions and salaries.

A Retrospective Study on Amoxicillin Susceptibility in Severe Haemophilus influenzae Pneumonia.

INTRODUCTION: Treatment of Haemophilus influenzae (Hi) pneumonia is on concern because resistance to amoxicillin is largely diffused. This study describes the evolution of resistance to amoxicillin and amoxicillin/clavulanic acid (AMC) in Hi isolates and characteristics of patients with Hi severe pneumonia. METHODS: A monocentric retrospective observational study including patients from 2008 to 2017 with severe pneumonia hospitalized in ICU. Evolution of amoxicillin and AMC susceptibility was showed. Characteristics of patients with Hi pneumonia were compared to characteristics of patients with Streptococcus pneumoniae (Sp) pneumonia, as reference. Risk factors for amoxicillin resistance in Hi were investigated. RESULTS: Overall, 113 patients with Hi and 132 with Sp pneumonia were included. The percentages of AMC resistance among Hi strains decreased over the years (from 10% in 2008-2009 to 0% in 2016-2017) while resistance to amoxicillin remained stable at 20%. Also, percentages of Sp resistant strains for amoxicillin decreased over years (from 25% to 3%). Patients with Hi pneumonia experienced higher prevalence of bronchitis (18% vs. 8%, p=0.02, chronic obstructive pulmonary disease (43% vs. 30% p=0.03), HAP (18% vs. 7%, p=0.01, ventilator-associated pneumonia (27% vs. 17%, p=0.04, and longer duration of mechanical ventilation (8 days vs. 6 days, p=0.04) than patients with Sp pneumonia. Patients with Sp pneumonia had more frequently local complications than patients with Hi pneumonia (17% vs. 7%, p=0.03). De-escalation of antibiotics was more frequent in patients with Sp than in patients with Hi (67% vs. 53%, p=0.03). No risk factors were associated with amoxicillin resistance among patients with Hi pneumonia. CONCLUSIONS: Amoxicillin resistance was stable over time, but no risk factors were detected. AMC resistance was extremely low, suggesting that AMC could be used for empiric treatment of Hi pneumonia, as well as other molecules, namely, cephalosporins. Patients with Hi pneumonia had more pulmonary comorbidities and severe diseases than patients with Sp pneumonia.

[Clinical and epidemiological characteristics of COVID-19]. / Caractéristiques cliniques et épidémiologiques de la Covid-19.

Severe acute respiratory syndrome coronavirus 2, the coronavirus with respiratory tropism responsible for COVID-19, was isolated for the first time in China at the end of 2019. Several months after its discovery and despite its pandemic spread, there are still many grey areas concerning the pathophysiology and treatment of COVID-19. However, we have strong data on its epidemiological characteristics and the clinical expression of this disease is now well described.

Negative Impact of Carbapenem Methylation on the Reactivity of ß-Lactams for Cysteine Acylation as Revealed by Quantum Calculations and Kinetic Analyses.

The Enterococcus faecium l,d-transpeptidase (Ldtfm) mediates resistance to most ß-lactam antibiotics in this bacterium by replacing classical peptidoglycan polymerases. The catalytic Cys of Ldtfm is rapidly acylated by ß-lactams belonging to the carbapenem class but not by penams or cephems. We previously reported quantum calculations and kinetic analyses for Ldtfm and showed that the inactivation profile is not determined by differences in drug binding (KD [equilibrium dissociation constant] values in the 50 to 80 mM range). In this study, we analyzed the reaction of a Cys sulfhydryl with various ß-lactams in the absence of the enzyme environment in order to compare the intrinsic reactivity of drugs belonging to the penam, cephem, and carbapenem classes. For this purpose, we synthesized cyclic Cys-Asn (cCys-Asn) to generate a soluble molecule with a sulfhydryl closely mimicking a cysteine in a polypeptide chain, thereby avoiding free reactive amino and carboxyl groups. Computational studies identified a thermodynamically favored pathway involving a concerted rupture of the ß-lactam amide bond and formation of an amine anion. Energy barriers indicated that the drug reactivity was the highest for nonmethylated carbapenems, intermediate for methylated carbapenems and cephems, and the lowest for penams. Electron-withdrawing groups were key reactivity determinants by enabling delocalization of the negative charge of the amine anion. Acylation rates of cCys-Asn determined by spectrophotometry revealed the same order in the reactivity of ß-lactams. We concluded that the rate of Ldtfm acylation is largely determined by the ß-lactam reactivity with one exception, as the enzyme catalytic pocket fully compensated for the detrimental effect of carbapenem methylation.

Epidemiology of infective endocarditis in French intensive care units over the 1997-2014 period-from CUB-Réa Network.

BACKGROUND: Few studies focus only on severe forms of infective endocarditis, for which organ failure requires admission to an intensive care unit (ICU). This study aimed to describe demographical, comorbidities, organ failure, and pathogen-related characteristics in a population of critically ill patients admitted to ICU for infective endocarditis and to identify risk factors of in-ICU mortality. METHODS: Retrospective observational multicenter (N = 34) study of the CUB-Rea register, based on ICD-10 coding rules, between 1997 and 2014 in France including ICU patients managed for infective endocarditis. In-ICU mortality associated factors were assessed by multivariate logistic regression including an interrupted time analysis of three periods (1997-2003, 2004-2009, and 2010-2014). RESULTS: Four thousand four hundred five patients admitted in ICU for infective endocarditis were included. We observed an increase in endocarditis prevalence, as well as an increase in organ failure severity over the three periods. In addition, valve surgery was more frequently performed (27%, 31%, and 42%, P < 0.0001) while in-ICU mortality significantly decreased (28%, 29%, and 23%, P < 0.001). Since 2010, a significant increase in the trends' slope of incidence for Streptococcus sp. and Staphylococcus sp. was observed with no change concerning intracellular bacteria, Enterococcus sp. or Candida sp. slope trends. In multivariate analysis, age, SAPS2, organ failure, stroke, and Staphylococcus sp. were associated with ICU mortality. Conversely, surgery, intracardiac devices, male gender, and Streptococcus sp.-related infective endocarditis were associated with a better outcome. CONCLUSIONS: Our study reveals a shifting landscape of infective endocarditis epidemiology in French ICUs, characterized by reduced in-ICU mortality despite higher severity, more surgery, and substantial changes in microbial epidemiology.

Reversible Microvascular Hyporeactivity to Acetylcholine During Diabetic Ketoacidosis.

OBJECTIVES: Metabolic acidosis is commonly observed in critically ill patients. Experimental studies suggested that acidosis by itself could impair vascular function, but this has been poorly investigated in human. DESIGN: Prospective observational study. SETTING: Medical ICU in a tertiary teaching hospital. PATIENTS: To assess the relationship between metabolic acidosis severity and microvascular reactivity, we included adult diabetic patients admitted in ICU for ketoacidosis. Microvascular response to acetylcholine iontophoresis was measured at admission (baseline) and after correction of metabolic acidosis (24 hr). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Thirty-nine patients with diabetic ketoacidosis were included (68% male), with a median age of 43 (31-57) years. At admission, microvascular reactivity negatively correlated with acidosis severity (R = -0.53; p < 0.001). Microvascular response was strongly depressed at pH less than 7.20 (area under the curve, 1,779 [740-3,079] vs 12,944 [4,874-21,596] at pH > 7.20; p < 0.0001). In addition, acidosis severity was significantly correlated with capillary refill time (R = 0.50; p = 0.02). At H24, after rehydration and insulin infusion, clinical and biological disorders were fully corrected. After acidosis correction, microvascular reactivity increased more in patients with severe baseline acidosis (pH < 7.20) than in those with mild baseline acidosis (area under the curve, +453% [213%-1,470%] vs +121% [79%-312%]; p < 0.01). CONCLUSIONS: We identified an alteration of microvascular reactivity during metabolic acidosis in critically ill patients with diabetic ketoacidosis. Microvascular hyporeactivity recovered after acidosis correction.

Functional outcomes in adults with tuberculous meningitis admitted to the ICU: a multicenter cohort study.

BACKGROUND: Tuberculous meningitis (TBM) is a devastating infection in tuberculosis endemic areas with limited access to intensive care. Functional outcomes of severe adult TBM patients admitted to the ICU in nonendemic areas are not known. METHODS: We conducted a retrospective multicenter cohort study (2004-2016) of consecutive TBM patients admitted to 12 ICUs in the Paris area, France. Clinical, biological, and brain magnetic resonance imaging (MRI) findings at admission associated with a poor functional outcome (i.e., a score of 3-6 on the modified Rankin scale (mRS) at 90 days) were identified by logistic regression. Factors associated with 1-year mortality were investigated by Cox proportional hazards modeling. RESULTS: We studied 90 patients, of whom 61 (68%) had a score on the Glasgow Coma Scale ≤ 10 at presentation and 63 (70%) required invasive mechanical ventilation. Brain MRI revealed infarction and hydrocephalus in 38/75 (51%) and 25/75 (33%) cases, respectively. A poor functional outcome was observed in 55 (61%) patients and was independently associated with older age (adjusted odds ratio (aOR) 1.03, 95% CI 1.0-1.07), cerebrospinal fluid protein level ≥ 2 g/L (aOR 5.31, 95% CI 1.67-16.85), and hydrocephalus on brain MRI (aOR 17.2, 95% CI 2.57-115.14). By contrast, adjunctive steroids were protective (aOR 0.13, 95% CI 0.03-0.56). The multivariable adjusted hazard ratio of adjunctive steroids for 1-year mortality (47%, 95% CI 37%-59%) was 0.23 (95% CI 0.11-0.44). Among survivors at 1 year, functional independence (mRS of 0-2) was observed in 27/37 (73%, 95% CI 59%-87%) cases. CONCLUSIONS: A poor functional outcome in adult TBM patients admitted to the ICU in a nonendemic area is observed in 60% of cases and is independently associated with elevated cerebrospinal fluid protein level and hydrocephalus. Our data also suggest a protective effect of adjunctive steroids, with reduced disability and mortality, irrespective of immune status and severity of disease at presentation. One-year follow-up revealed functional independence in most survivors.

Inhibition of ß-lactamases of mycobacteria by avibactam and clavulanate.

Objectives: Mycobacterium tuberculosis and Mycobacterium abscessus produce broad-spectrum class A ß-lactamases, BlaC and Bla Mab , which are inhibited by clavulanate and avibactam, respectively. BlaC differs from Bla Mab at Ambler position 132 in the conserved motif SDN (SDG versus SDN, respectively). Here, we investigated whether this polymorphism could account for the inhibition specificity of ß-lactamases from slowly and rapidly growing mycobacteria. Methods: Enzyme kinetics were determined to assess the impact of the substitutions G 132 N in BlaC and N 132 G in Bla Mab on ß-lactamase inhibition by clavulanate and avibactam. The stability of acylenzymes was evaluated by MS. The impact of the substitutions on the antibacterial activity of drug combinations was determined based on production of the ß-lactamases in Escherichia coli . Results: The substitution G 132 N increased 140-fold the efficacy of BlaC inhibition by avibactam and abolished clavulanate inhibition due to acylenzyme hydrolysis. Bla Mab efficiently hydrolysed clavulanate, but the substitution N 132 G led to a 5600-fold reduction in the hydrolysis rate constant k cat due to stabilization of Bla Mab -clavulanate covalent adducts. The N 132 G substitution also led to a 610-fold reduction in the efficacy of Bla Mab carbamylation by avibactam. Testing resistance to the amoxicillin/clavulanate and amoxicillin/avibactam combinations revealed that modifications in the catalytic properties of the ß-lactamases resulted in opposite shifts from susceptibility to resistance and vice versa. Conclusions: G 132 N and N 132 G had opposite effects on the inhibition of BlaC and Bla Mab , indicating that these substitutions might lead to acquisition of resistance to either of the ß-lactamase inhibitors, but not to both of them.