How should we treat acinetobacter pneumonia?

Safety and pharmacokinetics of SPR206 in subjects with varying degrees of renal impairment

SPR206 is a novel polymyxin derivative with potent in vitro activity against susceptible and multidrug-resistant strains of Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Enterobacter species. SPR206 is eliminated renally. The safety, tolerability, and pharmacokinetics (PK) of SPR206 were evaluated in healthy subjects with normal renal function (Cohort 1) and subjects with varying degrees of renal impairment (RI) (Cohorts 2-4) or end-stage renal disease (ESRD) on hemodialysis (HD) (Cohort 5). Subjects in Cohorts 1-4 received a 100-mg intravenous (IV) dose of SPR206. Subjects in Cohort 5 received a 100-mg IV dose within 2 h after HD on day 1 and 1 h before HD on day 5. Safety and PK analyses included 37 subjects. Mostly mild but no serious treatment-related adverse events were reported. Systemic exposure to SPR206 increased as renal function decreased, with mean area under the concentration-time curve from time 0 to the last quantifiable concentration (AUC0-last) values 39% to 239% greater in subjects with RI vs healthy subjects. Mean plasma clearance (CL) of SPR206 decreased with decreasing renal function (29% to 76% lower vs healthy subjects). In subjects with ESRD, AUC0-last decreased by 51%, and CL increased by 92% for dialyzed vs nondialyzed conditions. SPR206 was excreted in urine within 12 h in healthy subjects and subjects with mild RI (Cohort 2) but was prolonged in those with moderate and severe RI (Cohorts 3 and 4, respectively). In summary, SPR206 was generally safe and well tolerated, and the PK of SPR206 was well characterized in subjects with RI.

Pharmacokinetics of SPR206 in Plasma, Pulmonary Epithelial Lining Fluid, and Alveolar Macrophages following Intravenous Administration to Healthy Adult Subjects

SPR206 is a next-generation polymyxin being developed for the treatment of multidrug-resistant (MDR) Gram-negative infections. This Phase 1 bronchoalveolar lavage (BAL) study was conducted to evaluate SPR206's safety and pharmacokinetics in plasma, pulmonary epithelial lining fluid (ELF), and alveolar macrophages (AM) in healthy volunteers. Subjects received a 100 mg intravenous (IV) dose of SPR206 infused over 1 h every 8 h for 3 consecutive doses. Each subject underwent 1 bronchoscopy with BAL at 2, 3, 4, 6, or 8 h after the start of the third IV infusion. SPR206 concentrations in plasma, BAL, and cell pellet were measured with a validated LC-MS/MS assay. Thirty-four subjects completed the study and 30 completed bronchoscopies. Mean SPR206 peak concentrations (Cmax) in plasma, ELF, and AM were 4395.0, 735.5, and 860.6 ng/mL, respectively. Mean area under the concentration-time curve (AUC0-8) for SPR206 in plasma, ELF, and AM was 20120.7, 4859.8, and 6026.4 ng*h/mL, respectively. The mean ELF to unbound plasma concentration ratio was 0.264, and mean AM to unbound plasma concentration ratio was 0.328. Mean SPR206 concentrations in ELF achieved lung exposures above the MIC for target Gram-negative pathogens for the entire 8-h dosing interval. Overall, SPR206 was well tolerated; 22 subjects (64.7%) reported at least 1 treatment-emergent adverse event (TEAE). Of the 40 reported TEAEs, 34 (85.0%) were reported as mild in severity. The most frequent TEAEs were oral paresthesia (10 subjects [29.4%]) and nausea (2 subjects [5.9%]). This study demonstrates pulmonary penetration of SPR206 and supports further development of SPR206 for the treatment of patients with serious infections caused by MDR Gram-negative pathogens.

Short versus long course of colistin treatment for carbapenem-resistant A. baumannii in critically ill patients: A propensity score matching study

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) is one of the most commonly found nosocomial infections in critically ill patients. However, the appropriate treatment period for a specific group of critically ill patients with CRAB infection is currently being debated. Therefore, our study aimed to evaluate the optimal courses of therapy for critically ill patients with CRAB infection by comparing the outcomes of colistin therapy of short duration (< 14 days) versus long duration (≥ 14 days).

METHODS

A retrospective cohort study was conducted at Nakornping Hospital on critically ill patients with CRAB infection who received either a short or long course of colistin treatment between 2015 and 2022. The primary outcome was the 30-day mortality rate while secondary outcomes were clinical response, microbiological response, and nephrotoxicity. Propensity score matching with a 1: 1 ratio was performed to reduce potential biases. Furthermore, a logistic regression model was used to estimate the odds ratio (OR).

RESULTS

A total of 374 patients met the inclusion criteria. Two hundred and forty-eight patients were recruited after utilizing propensity scores to match patients at a 1: 1 ratio. The results from the propensity score matching analysis demonstrated that the long-course therapy group had a lower 30-day mortality rate compared to the short-course therapy group (adjusted OR (aOR) = 0.46, 95% CI: 0.26-0.83, p = 0.009). The clinical response and microbiological response rates were higher in patients who received the long course of colistin therapy compared to those receiving the short course (aOR = 3.24, 95% CI: 1.78-5.92, p = 0.001; aOR = 3.01, 95% CI: 1.63-5.57, p = 0.001). There was no significant different in the occurrence of nephrotoxicity (aOR = 1.28, 95% CI: 0.74-2.22, p = 0.368) between the two treatment groups.

CONCLUSION

A long course of colistin therapy resulted in a lower 30-day mortality rate in critically ill patients, and better clinical and microbiological outcomes, but similar nephrotoxicity as compared to a short course of colistin therapy. Therefore, a specific subset of critically ill patients who had CRAB infection needed to be considered for a long course of therapy.

Optimization of Pyrazole Compounds as Antibiotic Adjuvants Active against Colistin- and Carbapenem-Resistant Acinetobacter baumannii

The diffusion of antibiotic-resistant, Gram-negative, opportunistic pathogens, an increasingly important global public health issue, causes a significant socioeconomic burden. Acinetobacter baumannii isolates, despite causing a lower number of infections than Enterobacterales, often show multidrug-resistant phenotypes. Carbapenem resistance is also rather common, prompting the WHO to include carbapenem-resistant A. baumannii as a "critical priority" for the discovery and development of new antibacterial agents. In a previous work, we identified several series of compounds showing either direct-acting or synergistic activity against relevant Gram-negative species, including A. baumannii. Among these, two pyrazole compounds, despite being devoid of any direct-acting activity, showed remarkable synergistic activity in the presence of a subinhibitory concentration of colistin on K. pneumoniae and A. baumannii and served as a starting point for the synthesis of new analogues. In this work, a new series of 47 pyrazole compounds was synthesized. Some compounds showed significant direct-acting antibacterial activity on Gram-positive organisms. Furthermore, an evaluation of their activity as potential antibiotic adjuvants allowed for the identification of two highly active compounds on MDR Acinetobacter baumannii, including colistin-resistant isolates. This work confirms the interest in pyrazole amides as a starting point for the optimization of synergistic antibacterial compounds active on antibiotic-resistant, Gram-negative pathogens.

Treatment of Acinetobacter baumannii severe infections

Acinetobacter baumannii is a Gram-negative, multidrug-resistant (MDR) pathogen that causes nosocomial infections, especially in intensive care units (ICUs) and immunocompromised patients. A. baumannii has developed a broad spectrum of antimicrobial resistance, associated with a higher mortality rate among infected patients compared with other non-baumannii species. In terms of clinical impact, resistant strains are associated with increases in both in-hospital length of stay and mortality. A. baumannii can cause a variety of infections, especially ventilator-associated pneumonia, bacteremia, and skin wound infections, among others. The most common risk factors for the acquisition of MDR A. baumannii are previous antibiotic use, mechanical ventilation, length of ICU and hospital stay, severity of illness, and use of medical devices. Current efforts are focused on addressing all the antimicrobial resistance mechanisms described in A. baumannii, with the objective of identifying the most promising therapeutic scheme.

An Evidence-Based Multidisciplinary Approach Focused on Creating Algorithms for Targeted Therapy of Infection-Related Ventilator-Associated Complications (IVACs) Caused by Pseudomonas aeruginosa and Acinetobacter baumannii in Critically Ill Adult Patients

(1) Background: To develop evidence-based algorithms for targeted antibiotic therapy of infection-related ventilator-associated complications (IVACs) caused by non-fermenting Gram-negative pathogens. (2) Methods: A multidisciplinary team of four experts had several rounds of assessments for developing algorithms devoted to targeted antimicrobial therapy of IVACs caused by two non-fermenting Gram-negative pathogens. A literature search was performed on PubMed-MEDLINE (until September 2021) to provide evidence for supporting therapeutic choices. Quality and strength of evidence was established according to a hierarchical scale of the study design. Six different algorithms with associated recommendations in terms of therapeutic choice and dosing optimization were suggested according to the susceptibility pattern of two non-fermenting Gram-negative pathogens: multi-susceptible Pseudomonas aeruginosa (PA), multidrug-resistant (MDR) metallo-beta-lactamase (MBL)-negative-PA, MBL-positive-PA, carbapenem-susceptible Acinetobacter baumannii (AB), and carbapenem-resistant AB. (3) Results: Piperacillin–tazobactam or fourth-generation cephalosporins represent the first therapeutic choice in IVACs caused by multi-susceptible PA. A carbapenem-sparing approach favouring the administration of novel beta-lactam/beta-lactamase inhibitors should be pursued in the management of MDR-MBL-negative PA infections. Cefiderocol should be used as first-line therapy for the management of IVACs caused by MBL-producing-PA or carbapenem-resistant AB. Fosfomycin-based combination therapy, as well as inhaled colistin, could be considered as a reasonable alternative for the management of IVACs due to MDR-PA and carbapenem-resistant AB. (4) Conclusions: The implementation of algorithms focused on prompt revision of antibiotic regimens guided by results of conventional and rapid diagnostic methodologies, appropriate place in therapy of novel beta-lactams, implementation of strategies for sparing the broadest-spectrum antibiotics, and pharmacokinetic/pharmacodynamic optimization of antibiotic dosing regimens is strongly suggested.

Single- and Multiple-Ascending Dose Study of the Safety, Tolerability, and Pharmacokinetics of the Polymyxin Derivative, SPR206

Carbapenem-resistant Acinetobacter baumannii and Enterobacterales are identified as urgent threats, and multidrug-resistant (MDR) Pseudomonas aeruginosa and extended-spectrum beta-lactamase (ESBL)-producing pathogens are identified as serious threats by the Centers for Disease Control and Prevention (CDC). SPR206 is a novel polymyxin derivative with potent in vitro and in vivo activity against A. baumannii, P. aeruginosa, and multiple clinically important species of Enterobacterales, including multidrug- and extensively drug-resistant strains. This was a first-in-human (FIH) double-blind, placebo-controlled, single-, and multiple-ascending-dose study of the safety, tolerability, and pharmacokinetics (PK) of SPR206 in 94 healthy subjects. Following intravenous (i.v.) administration (1-h infusion) at single doses of 10 mg to 400 mg and multiple doses of 25 mg to 150 mg every 8 h (q8h) for 7 days and 100 mg q8h for 14 days, SPR206 was generally safe and generally well tolerated. While the incidence of adverse events increased with dose, most were of mild severity. Systemic exposure (maximum concentration of drug in serum [C_max] and area under the concentration-time curve [AUC]) to SPR206 was approximately dose proportional, time to peak concentrations ranged from 1.1 to 1.3 h, and half-life ranged from 2.4 to 4.1 h. No appreciable accumulation occurred with repeated dosing of SPR206, and trough concentrations suggest that steady state was achieved by day 2. Urinary excretion of unchanged SPR206 was dose dependent across single- (SAD) and multiple-ascending-dose (MAD) cohorts, and the percentage of dose excreted as SPR206 was up to >50%. Importantly, no evidence of nephrotoxicity was observed over 14 days of 100 mg q8h dosing of SPR206; a dosing regimen anticipated to exceed requirements for clinical efficacy. (This study has been registered at ClinicalTrials.gov under identifier NCT03792308.)

Clinical Pharmacokinetics and Pharmacodynamics of Lefamulin

Lefamulin (Xenleta) has been approved by the US FDA for the treatment of community-acquired bacterial pneumonia (CABP). It may be taken intravenously or orally and has activity against a broad range of pulmonary pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydophila pneumonia, as well as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. Lefamulin has an adverse effect profile that is similar to other antimicrobial agents commonly used to treat CABP. Despite these promising features, the use of lefamulin remains limited in clinical practice. However, given the rise of antibiotic-resistant organisms, this may soon change. This review examines what is known about the pharmacokinetics and pharmacodynamics of lefamulin and looks ahead to its potential applications in clinical practice, including the treatment of sexually transmitted infections such as multidrug-resistant Mycoplasma genitalium, as well as its role as a synergistic agent used in combination with other antimicrobials in the treatment of drug-resistant organisms.

Analysis of Nosocomial Infection and Risk Factors in Patients with ECMO Treatment

Objective

To investigate the drug resistance of nosocomial infection-related pathogens in patients who underwent extracorporeal membrane oxygenation (ECMO), analyzing the nosocomial infection-related risk factors.

Methods

The medical records of 56 patients who received ECMO support treatment in the First Affiliated Hospital with Nanjing Medical University from January 2013 to December 2019 were selected. The nosocomial infection, pathogen distribution and drug resistance, and the influencing factors of nosocomial infection were analyzed. The predictive value of independent risk factors for nosocomial infection after ECMO was analyzed using the receiver operating characteristic (ROC) curve.

Results

A total of 56 patients receiving ECMO treatment were included. The nosocomial infection rate was 28.57%, and the prevalence infection rate was 44.64%. Lower respiratory tract infection was the main infection site. Among these infectious patients, 53 strains of pathogens were detected. The results showed that the gram-negative bacteria were mainly Acinetobacter baumannii and Klebsiella pneumonia. Moreover, the drug resistance rate of Acinetobacter baumannii to most of the antibiotics was more than 65%, among which the drug resistance rate to carbapenems was 80%. The results of risk factors of nosocomial infection after ECMO were analyzed by univariate analysis, showing that ECMO treatment time, hospitalization time, antibacterial drug use time, ventilator use time, catheter intubation time and central venous intubation time were statistically significant (all p < 0.001). Multivariate analysis identified that ECMO treatment time was an independent risk factor. As showed by ROC curve, ECMO treatment time had a high predictive value for postoperative nosocomial infection. ECMO treatment times of more than 4.5 days were associated with an increased risk of nosocomial infection.

Conclusion

The nosocomial infection rate after ECMO was relatively high, and the main pathogens are Gram-negative bacteria. The selection of antibiotics should be based on the results of pathogen drug sensitivity.

Bacteriostatic Potential of Melatonin: Therapeutic Standing and Mechanistic Insights

Diseases caused by pathogenic bacteria in animals (e.g., bacterial pneumonia, meningitis and sepsis) and plants (e.g., bacterial wilt, angular spot and canker) lead to high prevalence and mortality, and decomposition of plant leaves, respectively. Melatonin, an endogenous molecule, is highly pleiotropic, and accumulating evidence supports the notion that melatonin's actions in bacterial infection deserve particular attention. Here, we summarize the antibacterial effects of melatonin in vitro, in animals as well as plants, and discuss the potential mechanisms. Melatonin exerts antibacterial activities not only on classic gram-negative and -positive bacteria, but also on members of other bacterial groups, such as Mycobacterium tuberculosis. Protective actions against bacterial infections can occur at different levels. Direct actions of melatonin may occur only at very high concentrations, which is at the borderline of practical applicability. However, various indirect functions comprise activation of hosts' defense mechanisms or, in sepsis, attenuation of bacterially induced inflammation. In plants, its antibacterial functions involve the mitogen-activated protein kinase (MAPK) pathway; in animals, protection by melatonin against bacterially induced damage is associated with inhibition or activation of various signaling pathways, including key regulators such as NF-κB, STAT-1, Nrf2, NLRP3 inflammasome, MAPK and TLR-2/4. Moreover, melatonin can reduce formation of reactive oxygen and nitrogen species (ROS, RNS), promote detoxification and protect mitochondrial damage. Altogether, we propose that melatonin could be an effective approach against various pathogenic bacterial infections.

Emergent Pneumonia in Children

In recent decades there have been multiple pathogens, viruses and bacteria, which have emerged as causal agents of pneumonia affecting adults, albeit less frequently, to children. For the purposes of this article we have classified emerging pathogens as follows: True emerging, to pathogens identified for the very first time affecting human population (SARS-CoV-1, SARS-CoV-2, MERS-CoV, avian influenza, and hantavirus); Re-emerging, to known pathogens which circulation was controlled once, but they have reappeared (measles, tuberculosis, antimicrobial resistant bacteria such as CA-MRSA, Mycoplasma pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and new serotypes of post-vaccine pneumococcal); and finally, those that we have called old known with new presentations, including common pathogens that, in particular condition, have changed their form of presentation (rhinovirus, and non-SARS coronavirus). We will review for each of them their epidemiology, forms of presentation, therapy, and prognosis in children compared to the adult with the aim of being able to recognize them to establish appropriate therapy, prognostics, and effective control measures.

Safety, Pharmacokinetics, and Drug-Drug Interaction Potential of Intravenous Durlobactam, a β-Lactamase Inhibitor, in Healthy Subjects

Durlobactam (DUR; also known as ETX2514) is a novel β-lactamase inhibitor with broad activity against Ambler class A, C, and D β-lactamases. Addition of DUR to sulbactam (SUL) in vitro restores SUL activity against clinical isolates of Acinetobacter baumannii. The safety and pharmacokinetics (PK) of DUR alone and with SUL and/or imipenem-cilastatin (IMI-CIL) were evaluated in healthy subjects. This was a randomized, placebo-controlled study. In part A, subjects, including a cohort of elderly subjects (which received DUR at 1 g), received single ascending doses of DUR ranging from 0.

Durlobactam (DUR; also known as ETX2514) is a novel β-lactamase inhibitor with broad activity against Ambler class A, C, and D β-lactamases. Addition of DUR to sulbactam (SUL) in vitro restores SUL activity against clinical isolates of Acinetobacter baumannii. The safety and pharmacokinetics (PK) of DUR alone and with SUL and/or imipenem-cilastatin (IMI-CIL) were evaluated in healthy subjects. This was a randomized, placebo-controlled study. In part A, subjects, including a cohort of elderly subjects (which received DUR at 1 g), received single ascending doses of DUR ranging from 0.25 to 8 g. In part B, multiple ascending doses of DUR ranging from 0.25 to 2 g were administered every 6 h (q6h) for 29 doses. In parts C and D, the drug-drug interaction (DDI) potential, including the safety, of DUR (1 g) with SUL (1 g) and/or IMI-CIL (0.5/0.5 g) was investigated after single and multiple doses. Plasma and urine concentrations of DUR, SUL, and IMI-CIL were determined. Among 124 subjects, DUR was generally safe and well tolerated when it was administered either alone or in combination with SUL and/or IMI-CIL. After single and multiple doses, DUR demonstrated linear dose-proportional exposure across the studied dose ranges. Renal excretion was a predominant clearance mechanism. No drug-drug interaction potential between DUR and SUL and/or IMI-CIL was identified. SUL-DUR at 1 g (of each component) administered q6h with a 3-h intravenous (i.v.) infusion is under development for the treatment of serious infections due to A. baumannii. (This study has been registered at ClinicalTrials.gov under identifier NCT02971423.)