Monitoring of Pseudomonas aeruginosa mutational resistome dynamics using an enrichment panel for direct sequencing of clinical samples.

BACKGROUND: Pseudomonas aeruginosa is a major cause of hospital-acquired and chronic infections, characterised by an extraordinary capacity to develop antimicrobial resistance through the selection of chromosomal mutations, leading to treatment failure. Here, we designed and tested a hybridisation-based capture system for the enrichment of genes of interest before sequencing to monitor resistant populations genomics directly from clinical samples. METHODS: A panel for enrichment before sequencing of close to 200 genes related to P. aeruginosa antimicrobial resistance, multilocus sequence typing, mutability or virulence was designed, synthesised (KAPA HyperCap, Roche) and initially validated in vitro using a multidrug-resistant ST175 isolate and representative isolates from major P. aeruginosa clades. In vivo testing included ventilator associated pneumonia by MDR P. aeruginosa in ICU (3-10 sequential samples from 3 patients) and chronic respiratory infection by hypermutable P. aeruginosa in cystic fibrosis (8 sequential samples from a single patient covering a 4-year period). Results from direct sequencing with the enrichment panel were compared with those of whole genome sequencing (WGS) and phenotypic profiling of 10 isolated colonies per sample. FINDINGS: In vitro assays confirmed the selectivity of the enrichment panel and the correct identification of the vast mutational resistome of ST175, including specific mutations even when introduced in a 1:100 proportion. In vivo performance was at least equivalent to sequencing 10 colonies per sample, including the accurate identification of the sequence types and the basal and acquired mutational resistome. To note, specific resistance mutations, such as those in ampC leading to resistance to novel ß-lactams, could be traced even at frequencies of 1%. Moreover, the coselection of mutator populations and antibiotic resistance mutations, predicted in theoretical and in vitro studies, was evidenced in vivo. INTERPRETATION: This proof-of-concept study demonstrates that resistance genomics of P. aeruginosa can be analysed directly from clinical samples, determining not only a considerable reduction in turnaround time and cost from a diagnostics perspective, but also an unprecedented potency for accurate monitoring of in vivo population dynamics in bacterial infections. FUNDING: Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación and Unión Europea-NextGenerationEU.

A systematic review of dalbavancin efficacy as a sequential therapy for infective endocarditis.

INTRODUCTION: Dalbavancin is an antibiotic characterized by an extended half-life and efficacy against methicillin-resistant Staphylococci. Currently, there are only narrative reviews summarizing the evidence about the use of dalbavancin for infective endocarditis (IE), many of which are focused primarily on its use as consolidation therapy. For this reason, we conducted a systematic review to describe the clinical efficacy and the safety of dalbavancin in IE treatment. METHODS: We searched for available evidence using the MEDLINE (PubMed), Embase, Scopus, Cochrane Library and Web of Science libraries, with no restrictions regarding the publication year. The risk of bias was performed using the Cochrane ROBINS-I tool for the comparative studies and the Newcastle-Ottawa Scale for descriptive studies. RESULTS: Nine studies were included. All of them were observational. Native valve endocarditis was the most common kind of IE found in the studies' populations (128/263, 48.7%), followed by prosthetic valve endocarditis, and cardiovascular implantable electronic device-related endocarditis. Coagulase-negative Staphylococci were the most common pathogens isolated (83/269, 30.1%), followed by S. aureus, Enterococci spp and Streptococci spp. Five out of nine studies documented a clinical failure rate of less than 10%. Dalbavancin showed a favourable safety profile. Dalbavancin appears to be a promising option for the consolidation therapy of IE. However, further studies comparing dalbavancin with standard of care are needed. PROSPERO REGISTRATION NUMBER: CRD42023430032.

Synergistic efficacy of ceftazidime/avibactam and aztreonam against carbapenemase-producing Pseudomonas aeruginosa: insights from the hollow-fiber infection model.

BACKGROUND: Combination therapy is an attractive therapeutic option for extensively drug-resistant (XDR) Pseudomonas aeruginosa infections. Existing data support the combination of aztreonam and ceftazidime/avibactam (CZA) against class serine-ß-lactamase (SBL)- and metallo-ß-lactamase (MBL) - producing Enterobacterales. However, data about that combination against SBL- and MBL-producing P. aeruginosa are scarce. The objective of the study was to assess the in vitro activity of CZA and aztreonam alone and in combination against SBL- and MBL-producing XDR P. aeruginosa isolates. METHODS: The combination was analyzed by means of the hollow-fiber infection model in three selected carbapenemase-producing P. aeruginosa isolates that were representative of the three most common XDRP. aeruginosa high-risk clones (ST175, ST111, ST235) responsible for global nosocomial infection outbreaks. RESULTS: The three isolates were nonsusceptible to CZA and nonsusceptible to aztreonam. In the dynamic hollow-fiber infection model, the combination of CZA plus aztreonam exerts a bactericidal effect on the isolates, regardless of their resistance mechanism and demonstrates synergistic interactions against three isolates, achieving a bacterial reduction of 5.07 log10 CFU/ml, 5.2 log10 CFU/ml and 4 log10 CFU/ml, respectively. CONCLUSION: The combination of CZA and aztreonam significantly enhanced the in vitro efficacy against XDR P. aeruginosa isolates compared to each monotherapy. This improvement suggests that the combination could serve as a feasible treatment alternative for infections caused by carbapenemase-producing XDR P. aeruginosa, especially in scenarios where no other treatment options are available.

Ceftazidime-Avibactam in the Treatment of Patients with Bacteremia or Nosocomial Pneumonia: A Systematic Review and Meta-analysis.

INTRODUCTION: Ceftazidime-avibactam (CAZ-AVI) is a combination of the third-generation cephalosporin ceftazidime and the novel, non-ß-lactam ß-lactamase inhibitor avibactam that is approved for the treatment of pediatric (≥ 3 months) and adult patients with complicated infections including hospital-acquired and ventilator-associated pneumonia (HAP/VAP), and bacteremia. This systematic literature review and meta-analysis (PROSPERO registration: CRD42022362856) aimed to provide a quantitative and qualitative synthesis to evaluate the effectiveness of CAZ-AVI in treating adult patients with bacteremia or nosocomial pneumonia caused by carbapenem-resistant Enterobacterales (non metallo-ß-lactamase-producing strains) and multi-drug resistant (MDR) Pseudomonas aeruginosa infections. METHODS: The databases included in the search, until November 7, 2022, were Embase and PubMed. A total of 24 studies (retrospective: 22, prospective: 2) with separate outcomes for patients with bacteremia or pneumonia were included. RESULTS: The outcomes assessed were all-cause mortality, clinical cure, and microbiological cure. Qualitative (24 studies) and quantitative (8/24 studies) syntheses were performed. The quality of the studies was assessed using the MINORS checklist and the overall risk of bias was moderate to high. CONCLUSIONS: In studies included in the meta-analysis, lower all-cause mortality for patients with bacteremia (OR = 0.30, 95% CI 0.19-0.46) and improved rates of clinical cure for patients with bacteremia (OR = 4.90, 95% CI 2.60-9.23) and nosocomial pneumonia (OR = 3.20, 95% CI 1.55-6.60) was observed in the CAZ-AVI group compared with the comparator group. Data provided here may be considered while using CAZ-AVI for the treatment of patients with difficult-to-treat infections. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42022362856.

Impact of an antimicrobial stewardship program indicator on the appropriateness of the empiric antibiotic treatment of urinary source Escherichia coli bacteraemia.

A prospective multicentre study was carried out between 2017 and 2021 to assess (1) the appropriateness of the empirical treatment to the local guidelines of urinary source Escherichia coli bacteraemia, (2) the appropriateness of empirical treatment to antibiotic sensitivity results and (3) the degree of error in the local guidelines regarding the antibiotic sensitivity reported in acute care hospitals enrolled in the vigilància de les infeccions relacionades amb l'atenció sanitària de Catalunya program. During the study period, 79.0% of the empirical treatments analysed complied with the guidelines and 88.1% were appropriate in view of the in vitro activity of the isolated strain. The rate of appropriateness rose from 73.8% in 2017 to 81.0% in 2021 (P < 0.001). The degree of error in the recommendations regarding the in vitro activity of the isolated strains was 5.9% and remained stable during the study period. Antibiotic families correctly prescribed according to the guidelines were third-generation cephalosporins (54.9%), carbapenems (16.8%) and combinations of penicillins and beta-lactamase inhibitors (16.4%). Of the 8009 E. coli strains, 19.0% were extended-spectrum beta-lactamases producers, 36.8% were resistant to quinolones and 0.5% were resistant to carbapenems. The broad implementation of an antimicrobial stewardship program with quality indicators of antibiotic use improved compliance to local guidelines in the empiric treatment of urinary tract E. coli bacteraemia. The degree of error in local guidelines was low but higher in more complex hospitals and in healthcare-associated infections. Guidelines need to be constantly updated with the use of epidemiological data, rapid diagnostic tests and the analysis of patient risk factors specific to each geographical area.

Pseudomonas stutzeri bloodstream infection is a prevailing community-onset disease with important mortality rates: results from a retrospective observational study in Australia.

BACKGROUND: The recognition of Pseudomonas stutzeri as a cause of infections in humans has been increasing. However, only case reports and small series of P. stutzeri bloodstream infections have been published. Epidemiological data on these infections are extremely scarce. Our objective was to describe the incidence, epidemiology, antimicrobial resistance rates, and outcomes of P. stutzeri bloodstream infections in a large population-based cohort in Australia. METHODS: Retrospective, laboratory-based surveillance study conducted in Queensland, Australia (population ≈ 5 million) during 2000-2019. Clinical information was obtained from public hospital admissions and vital statistics databases. RESULTS: In total, 228 episodes of P. stutzeri bloodstream infections were identified. Increased incidence was observed in the later years, especially in older men, and was higher during the rainy months of the year and in the warmest and more humid regions of the state. The majority of bloodstream infections were community-onset with 120 (52.6%) community-associated and 59 (25.9%) ambulatory healthcare-associated episodes. Only 49 cases (21.5%) were nosocomial. The most common foci of infection were skin and soft tissue, lower respiratory tract, and intra-abdominal. No isolate showed antimicrobial resistance. Thirty-one patients (13.6%) died. The mortality rate in patients with a respiratory infectious source was higher (21%). CONCLUSIONS: P. stutzeri bloodstream infection was predominantly a community-onset condition including ambulatory healthcare related cases, with increasing incidence, especially in older males. No antimicrobial resistance was observed. Mortality was high in patients with respiratory infectious source. This new observational data have implications when considering the epidemiology of these infections and for patient management.

Safety and efficacy of favipiravir in COVID-19 patients with pneumonia. A randomized, double-blind, placebo-controlled study (FAVID).

PURPOSE: To design a randomized clinical trial to assess the efficacy and safety of favipiravir in patients with COVID-19 disease with pneumonia. METHODS: A randomized, double blind, placebo-controlled clinical trial of favipiravir in patients with COVID-19 pneumonia was conducted in three Spanish sites. Randomization 1:1 to favipiravir or placebo (in both groups added to the Standard of Care) was performed to treat the patients with COVID-19 pneumonia. The primary endpoint was "time to clinical improvement," measured as an improvement for ≥ two categories on a 7-point WHO ordinal scale in an up to 28 days' time frame. RESULTS: Forty-four patients were randomized (23 in the favipiravir group and 21 in the placebo group). The median time to clinical improvement was not different between the favipiravir and the placebo arms (10 days for both groups) and none of the secondary endpoints showed significant differences between arms. The proportion of adverse events (both serious and non-serious) was statistically different between the favipiravir group (68.29%) and the placebo group (31.7%) (p = 0.019), but there was insufficient statistical evidence to correlate the degree of severity of the events with the treatment group. CONCLUSIONS: Favipiravir administered for ten days to patients with COVID-19 and pneumonia did not improve outcomes compared with placebo. Although this is an underpowered negative study, efficacy results align with other randomized trials. However, in the present study, the non-serious adverse events were more frequent in the favipiravir group.

Viral and Host Factors Are Associated With Mortality in Hospitalized Patients With COVID-19.

BACKGROUND: Persistent mortality in adults hospitalized due to acute COVID-19 justifies pursuit of disease mechanisms and potential therapies. The aim was to evaluate which virus and host response factors were associated with mortality risk among participants in Therapeutics for Inpatients with COVID-19 (TICO/ACTIV-3) trials. METHODS: A secondary analysis of 2625 adults hospitalized for acute SARS-CoV-2 infection randomized to 1 of 5 antiviral products or matched placebo in 114 centers on 4 continents. Uniform, site-level collection of participant baseline clinical variables was performed. Research laboratories assayed baseline upper respiratory swabs for SARS-CoV-2 viral RNA and plasma for anti-SARS-CoV-2 antibodies, SARS-CoV-2 nucleocapsid antigen (viral Ag), and interleukin-6 (IL-6). Associations between factors and time to mortality by 90 days were assessed using univariate and multivariable Cox proportional hazards models. RESULTS: Viral Ag ≥4500 ng/L (vs <200 ng/L; adjusted hazard ratio [aHR], 2.07; 1.29-3.34), viral RNA (<35 000 copies/mL [aHR, 2.42; 1.09-5.34], ≥35 000 copies/mL [aHR, 2.84; 1.29-6.28], vs below detection), respiratory support (<4 L O2 [aHR, 1.84; 1.06-3.22]; ≥4 L O2 [aHR, 4.41; 2.63-7.39], or noninvasive ventilation/high-flow nasal cannula [aHR, 11.30; 6.46-19.75] vs no oxygen), renal impairment (aHR, 1.77; 1.29-2.42), and IL-6 >5.8 ng/L (aHR, 2.54 [1.74-3.70] vs ≤5.8 ng/L) were significantly associated with mortality risk in final adjusted analyses. Viral Ag, viral RNA, and IL-6 were not measured in real-time. CONCLUSIONS: Baseline virus-specific, clinical, and biological variables are strongly associated with mortality risk within 90 days, revealing potential pathogen and host-response therapeutic targets for acute COVID-19 disease.

Efficacy and safety of rezafungin and caspofungin in candidaemia and invasive candidiasis: pooled data from two prospective randomised controlled trials.

BACKGROUND: Rezafungin, a new US Food and Drug Administration-approved, long-acting echinocandin to treat candidaemia and invasive candidiasis, was efficacious with a similar safety profile to caspofungin in clinical trials. We conducted pooled analyses of the phase 2 STRIVE and phase 3 ReSTORE rezafungin trials. METHODS: ReSTORE was a multicentre, double-blind, double-dummy, randomised phase 3 trial conducted at 66 tertiary care centres in 15 countries. STRIVE was a multicentre, double-blind, double-dummy, randomised phase 2 trial conducted at 44 centres in 10 countries. Adults (≥18 years) with candidaemia or invasive candidiasis were treated with once-a-week intravenous rezafungin (400 mg and 200 mg) or once-a-day intravenous caspofungin (70 mg and 50 mg). Efficacy was evaluated in a pooled modified intent-to-treat (mITT) population. Primary efficacy endpoint was day 30 all-cause mortality (tested for non-inferiority with a pre-specified margin of 20%). Secondary efficacy endpoint was mycological response. Safety was also evaluated. The STRIVE and ReSTORE trials are registered with ClinicalTrials.gov, NCT02734862 and NCT03667690, and both studies are complete. FINDINGS: ReSTORE was conducted from Oct 12, 2018, to Oct 11, 2021, and STRIVE from July 26, 2016, to April 18, 2019. The mITT population, pooling the data from the two trials, comprised 139 patients for rezafungin and 155 patients for caspofungin. Day 30 all-cause mortality rates were comparable between groups (19% [26 of 139] for the rezafungin group and 19% [30 of 155] for the caspofungin group) and the upper bound of the 95% CI for the weighted treatment difference was below 10% (-1·5% [95% CI -10·7 to 7·7]). Mycological eradication occurred by day 5 in 102 (73%) of 139 rezafungin patients and 100 (65%) of 155 caspofungin patients (weighted treatment difference 10·0% [95% CI -0·3 to 20·4]). Safety profiles were similar across groups. INTERPRETATION: Rezafungin was non-inferior to caspofungin for all-cause mortality, with a potential early treatment benefit, possibly reflecting rezafungin's front-loaded dosing regimen. These findings are of clinical importance in fighting active and aggressive infections and reducing the morbidity and mortality caused by candidaemia and invasive candidiasis. FUNDING: Melinta Therapeutics and Cidara Therapeutics.

Executive summary: Guidelines for the diagnosis and treatment of septic arthritis in adults and children, developed by the GEIO (SEIMC), SEIP and SECOT.

Infection of a native joint, commonly referred to as septic arthritis, is a medical emergency because of the risk of joint destruction and subsequent sequelae. Its diagnosis requires a high level of suspicion. These guidelines for the diagnosis and treatment of septic arthritis in children and adults are intended for use by any physician caring for patients with suspected or confirmed septic arthritis. They have been developed by a multidisciplinary panel with representatives from the Bone and Joint Infections Study Group (GEIO) belonging to the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), the Spanish Society of Paediatric Infections (SEIP) and the Spanish Society of Orthopaedic Surgery and Traumatology (SECOT), and two rheumatologists. The recommendations are based on evidence derived from a systematic literature review and, failing that, on the opinion of the experts who prepared these guidelines. A detailed description of the background, methods, summary of evidence, the rationale supporting each recommendation, and gaps in knowledge can be found online in the complete document.

Real-world experience of therapeutic drug monitoring and PK/PD achievement of ceftaroline administered by different infusion regimens in patients with confirmed infections caused by Gram-positive bacteria.

BACKGROUND: Ceftaroline is a novel cephalosporin active against MDR Gram-positive (GP) bacteria. For ß-lactam antibiotics, such as ceftaroline, prolonged infusions and therapeutic drug monitoring (TDM) are used for dosage optimization based on their pharmacokinetics/pharmacodynamics (PK/PD). OBJECTIVES: To describe our experience with TDM and PK/PD target attainment of ceftaroline administered by intermittent and prolonged infusion in a cohort of patients with MDR-GP bacterial infections. METHODS: Patients treated with ceftaroline administered by continuous (24 h), extended (3 h/6 h) and intermittent infusion (1 h) and undergoing TDM of plasma concentrations were included. A 100%fT>4×MIC was the pre-specified PK/PD target and 100%fT>10×MIC was considered overexposure. Dose recommendations were made based on TDM results and each patient's clinical condition. RESULTS: Twelve patients [83.3% male, median age of 73 (38-83) years] were included. Nine patients (75%) achieved 100%fT>4×MIC, all under prolonged infusions. In one patient, the 100%fT was >10×MIC but no toxicity was observed. Based on TDM results, initial doses were recommended to be maintained in eight patients, decreased in three and increased in one. CONCLUSIONS: The administration of ceftaroline by prolonged infusion together with TDM may be a useful strategy for achieving the desired PK/PD target in these patients. However, more studies evaluating the relationship between PK/PD attainment and clinical outcomes are needed.

Clinical, Microbiological and Treatment Characteristics of Severe Postoperative Respiratory Infections: An Observational Cohort Study.

Respiratory infections are frequent and life-threatening complications of surgery. This study aimed to evaluate the clinical, microbiological and treatment characteristics of severe postoperative pneumonia (POP) and tracheobronchitis (POT) in a large series of patients. This single-center, prospective observational cohort study included patients with POP or POT requiring intensive care unit admission in the past 10 years. We recorded demographic, clinical, microbiological and therapeutic data. A total of 207 patients were included, and 152 (73%) were men. The mean (SD) age was 70 (13) years and the mean (SD) ARISCAT score was 46 (19). Ventilator-associated pneumonia was reported in 21 patients (10%), hospital-acquired pneumonia was reported in 132 (64%) and tracheobronchitis was reported in 54 (26%). The mean (SD) number of days from surgery to POP/POT diagnosis was 6 (4). The mean (SD) SOFA score was 5 (3). Respiratory microbiological sampling was performed in 201 patients (97%). A total of 177 organisms were cultured in 130 (63%) patients, with a high proportion of Gram-negative and multi-drug resistant (MDR) bacteria (20%). The most common empirical antibiotic therapy was a triple-drug regimen covering MDR Gram-negative bacteria and MRSA. In conclusion, surgical patients are a high-risk population with a high proportion of early onset severe POP/POT and nosocomial bacteria isolation.

Staphylococcus aureus surgical site infection rates in 5 European countries.

OBJECTIVE: To determine the overall and procedure-specific incidence of surgical site infections (SSI) caused by Staphylococcus aureus (S. aureus) as well as risk factors for such across all surgical disciplines in Europe. METHODS: This is a retrospective cohort of patients with surgical procedures performed at 14 European centres in 2016, with a nested case-control analysis. S. aureus SSI were identified by a semi-automated crossmatching bacteriological and electronic health record data. Within each surgical procedure, cases and controls were matched using optimal propensity score matching. RESULTS: A total of 764 of 178 902 patients had S. aureus SSI (0.4%), with 86.0% of these caused by methicillin susceptible and 14% by resistant pathogens. Mean S. aureus SSI incidence was similar for all surgical specialties, while varying by procedure. CONCLUSIONS: This large procedure-independent study of S. aureus SSI proves a low overall infection rate of 0.4% in this cohort. It provides proof of principle for a semi-automated approach to utilize big data in epidemiological studies of healthcare-associated infections. Trials registration The study was registered at clinicaltrials.gov under NCT03353532 (11/2017).

Reducing the duration of antibiotic therapy in surgical patients through a specific nationwide antimicrobial stewardship program. A prospective, interventional cohort study.

BACKGROUND: Guidelines recommend 5-7 days of antibiotic treatment in patients with surgical infection and adequate source control. This nationwide stewardship intervention aimed to reduce the duration of treatments in surgical patients to <7 days. METHODS: Prospective cohort study evaluating surgical patients receiving antibiotics ≥7 days in 32 hospitals. Indication for treatment, quality of source control, type of recommendations issued, and adherence to the recommendations were analysed. Temporal trends in the percentages of patients with treatment >7 days were evaluated using a linear regression model and Pearson's correlation coefficients. RESULTS: A total of 32 499 patients were included. Of these, 13.7% had treatments ≥7 days. In all, 3912 stewardship interventions were performed, primarily in general surgery (90.7%) and urology (8.1%). The main types of infection were intra-abdominal (73.4%), skin/soft tissues (9.8%) and urinary (9.2%). The septic focus was considered controlled in 59.9% of cases. Out of 5458 antibiotic prescriptions, the most frequently analysed drugs were piperacillin/tazobactam (21.7%), metronidazole (11.2%), amoxicillin/clavulanate (10.3%), meropenem (10.7%), ceftriaxone (9.3%) and ciprofloxacin (6.7%). The main recommendations issued were: treatment discontinuation (35.0%), maintenance (40.0%) or de-escalation (15.5%), and the overall adherence rate was 91.5%. With adequate source control, the most frequent recommendation was to terminate treatment (51.2%). Throughout the study period, a significant decrease in the percentage of prolonged treatments was observed (Pc=-0.69;P < 0.001). CONCLUSIONS: This stewardship programme reduced the duration of treatments in surgical departments. Preference was given to general surgery services, intra-abdominal infection, and beta-lactam antibiotics, including carbapenems. Adherence to the issued recommendations was high.

Treatment of COVID-19 during the Acute Phase in Hospitalized Patients Decreases Post-Acute Sequelae of COVID-19.

BACKGROUND: The post-acute sequelae of SARS-CoV-2 (PASC) infection have caused a significant impact on our health system, but there is limited evidence of approved drugs focused on its prevention. Our objective was to identify risk factors that can determine the presence of PASC, with special attention to the treatment received in the acute phase, and to describe the profile of persistent symptoms in a multidisciplinary Post-Coronavirus Disease-19 (COVID-19) Unit. METHODS: This one-year prospective observational study included patients following an acute COVID-19 infection, irrespective of whether they required hospital admission. A standardized symptom questionnaire and blood sampling were performed at the first follow-up visit, and demographic and clinical electronic data were collected. We compared subjects with PASC with those who had fully recovered. Multivariate logistic regression was performed to identify factors associated with PASC in hospitalized patients, and Kaplan-Meier curves were used to assess duration of symptoms according to disease severity and treatments received in the acute phase. RESULTS: 1966 patients were evaluated; 1081 had mild disease, 542 moderate and 343 severe; around one third of the subjects had PASC, and were more frequently female, with obesity, asthma, and eosinophilia during acute COVID-19 disease. Patients who received treatment with dexamethasone and remdesivir during the course of the acute illness showed a lower median duration of symptoms, compared with those who received none of these treatments. CONCLUSION: Treatment with dexamethasone and/or remdesivir may be useful to reduce the impact of PASC secondary to SARS-CoV-2 infection. In addition, we identified female gender, obesity, asthma, and disease severity as risk factors for having PASC.

Suboptimal Concentrations of Ceftazidime/Avibactam (CAZ-AVI) May Select for CAZ-AVI Resistance in Extensively Drug-Resistant Pseudomonas aeruginosa: In Vivo and In Vitro Evidence.

This study correlates in vivo findings in a patient with an extensively drug-resistant (XDR) P. aeruginosa infection who developed resistance to ceftazidime-avibactam (CAZ-AVI) with in vitro results of a 7-day hollow-fiber infection model (HFIM) testing the same bacterial strain. The patient was critically ill with ventilator-associated pneumonia caused by XDR P. aeruginosa ST175 with CAZ-AVI MIC of 6 mg/L and was treated with CAZ-AVI in continuous infusion at doses adjusted for renal function. Plasma concentrations of CAZ-AVI were analyzed on days 3, 7, and 10. In the HIFM, the efficacy of different steady-state concentrations (Css) of CAZ-AVI (12, 18, 30 and 48 mg/L) was evaluated. In both models, a correlation was observed between the decreasing plasma levels of CAZ-AVI and the emergence of resistance. In the HIFM, a Css of 30 and 48 mg/L (corresponding to 5× and 8× MIC) had a bactericidal effect without selecting resistant mutants, whereas a Css of 12 and 18 mg/L (corresponding to 2× and 3× MIC) failed to prevent the emergence of resistance. CAZ/AVI resistance development was caused by the selection of a single ampC mutation in both patient and HFIM. Until further data are available, strategies to achieve plasma CAZ-AVI levels at least 4× MIC could be of interest, particularly in severe and high-inoculum infections caused by XDR P. aeruginosa with high CAZ-AVI MICs.

A profile of delafloxacin in the treatment of adults with community-acquired bacterial pneumonia.

INTRODUCTION: Community-acquired bacterial pneumonia (CABP) is the most common infectious cause of hospital admission in adults, and poses a significant clinical and economic burden. At the same time, antimicrobial resistance is increasing worldwide with only a few new antibiotics developed in recent years. Delafloxacin is an anionic fluoroquinolone available in intravenous and oral formulations and with a broad spectrum of activity targeting Gram-positives, including methicillin-resistant Staphylococcus aureus (MRSA), gram-negative organisms, and atypical and anaerobic organisms. It also has a better adverse event profile compared to other fluoroquinolones. AREAS COVERED: This article reviews the current epidemiology of CABP, etiologic agents and current resistance rates, current treatment guidelines, characteristics of delafloxacin (chemistry, microbiology, PK/PD), clinical efficacy and safety in pneumonia and other indications, and regulatory affairs. EXPERT OPINION: Delafloxacin's susceptibility profile against respiratory pathogens, bioequivalent intravenous and oral formulations and favorable safety profile, support its use for the treatment of CABP. It could be useful as empirical treatment in countries with high rates of penicillin-resistant S. pneumoniae and in patients with suspected or documented pneumonia due to MRSA. In post-influenza staphylococcal bacterial pneumonia, MRSA could be also considered an important pathogen.