In vitro activity of beta-lactam antibiotics to community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA)

Safety of ceftobiprole in patients with impaired renal, hepatic or immune function: a multinational retrospective hospital chart review (RETRACE study)

Ceftobiprole, an advanced-generation cephalosporin with broad bactericidal activity, is approved for community-acquired and hospital-acquired pneumonia (excluding ventilator-associated pneumonia). We aimed to evaluate, in a real-world setting, the safety profile of ceftobiprole in patients with risk conditions (severe renal impairment, hepatic impairment, and immunocompromised status), groups excluded from clinical trials. In this retrospective study (NCT04170309), 396 consecutive charts of patients treated with ceftobiprole during 2016-2022 in 15 centers in France, Italy, and Spain were analyzed: 62 had severe renal impairment, 51 had hepatic impairment, 120 were immunocompromised, and 203 had no predefined risk condition (controls). Ceftobiprole was used for off-label indications in 110/396 (27.8%) patients; 46/396 (11.6%) patients received a higher-than-recommended dose. Treatment-emergent adverse events (TEAEs) considered as ceftobiprole-related occurred in 44 patients, more frequently in the risk groups compared to controls (severe renal impairment: 8/62 [12.9%]; hepatic impairment: 7/51 [13.7%]; immunocompromised: 19/120 [15.8%]; controls: 15/203, [7.4%]); in 7/44 patients, these events were serious. Compared to controls, liver-related AEs occurred more frequently in the impaired hepatic function (17/51 [33.3%] vs 22/203 [10.8%], odds ratio [OR:]: 4.11; 95% confidence interval [CI]: 1.98-8.55) and immunocompromised (30/120 [25.0%] vs 22/203 [10.8%], OR: 2.74; 95%CI: 1.50-5.02) groups. Hyponatremia was also more frequent in immunocompromised patients than controls (14/120 [11.7%] vs 9/203 [4.4%], OR: 2.85; 95%CI: 1.19-6.80). Underlying disease, concomitant medications and the poor health status of the patients likely affected these imbalances. Overall, no new safety concerns related to ceftobiprole use in real-world patients with severe renal impairment, hepatic impairment or immunocompromised status were identified.

Cefepime/Enmetazobactam: a microbiological, pharmacokinetic, pharmacodynamic, and clinical evaluation

INTRODUCTION

Cefepime/enmetazobactam is a novel β-lactam/β-lactamase inhibitor (BL-BLI) combination with broad Gram-positive and -negative activity. Cefepime is relatively resistant to hydrolysis by AmpC, and enmetazobactam inhibits all Ambler Class A extended spectrum β-lactamases (ESBLs). Hence, the combination is resistant to hydrolysis by many ESBLs. Important spectrum gaps are MRSA, enterococci, Acinetobacter spp. and anaerobes. There is no completely reliable activity against carbapenem-resistant organisms.

AREAS COVERED

We describe the chemistry, pharmacodynamics, pharmacokinetics, toxicities, drug-drug interactions, clinical efficacy, and current regulatory position of cefepime/enmetazobactam, following a review of available published literature relating to cefepime/enmetazobactam.

EXPERT OPINION

The main potential role for cefepime/enmetazobactam is as a carbapenem-sparing agent for the treatment of infections caused by ESBL-producing Enterobacterales to prevent the use of carbapenems and to avoid the toxicities of non-β-lactam alternatives.There may be potential uses for cefepime/enmetazobactam for the treatment of reproductive tract infections, abdominal infections and neonatal sepsis, given the spectrum of activity and pharmacokinetic properties. However, additional non-clinical and clinical studies are required before use in these settings.

Potential Antibiotics for the Treatment of Neonatal Sepsis Caused by Multidrug-Resistant Bacteria

Neonatal sepsis causes up to an estimated 680,000 deaths annually worldwide, predominantly in low- and middle-income countries (LMICs). A significant and growing proportion of bacteria causing neonatal sepsis are resistant to multiple antibiotics, including the World Health Organization-recommended empiric neonatal sepsis regimen of ampicillin/gentamicin. The Global Antibiotic Research and Development Partnership is aiming to develop alternative empiric antibiotic regimens that fulfil several criteria: (1) affordable in LMIC settings; (2) activity against neonatal bacterial pathogens, including extended-spectrum β-lactamase producers, gentamicin-resistant Gram-negative bacteria, and methicillin-resistant Staphylococcus aureus (MRSA); (3) a licence for neonatal use or extensive experience of use in neonates; and (4) minimal toxicities. In this review, we identify five antibiotics that fulfil these criteria: amikacin, tobramycin, fosfomycin, flomoxef, and cefepime. We describe the available characteristics of each in terms of mechanism of action, resistance mechanisms, clinical pharmacokinetics, pharmacodynamics, and toxicity profile. We also identify some knowledge gaps: (1) the neonatal pharmacokinetics of cefepime is reliant on relatively small and limited datasets, and the pharmacokinetics of flomoxef are also reliant on data from a limited demographic range and (2) for all reviewed agents, the pharmacodynamic index and target has not been definitively established for both bactericidal effect and emergence of resistance, with many assumed to have an identical index/target to similar class molecules. These five agents have the potential to be used in novel combination empiric regimens for neonatal sepsis. However, the data gaps need addressing by pharmacokinetic trials and pharmacodynamic characterisation.

Evaluation of the pharmacokinetics of imipenem following regional limb perfusion using the saphenous and the cephalic veins in standing horses

This prospective experimental study goal was to determine the pharmacokinetics of imipenem after intravenous regional limb perfusion (IV-RLP) in standing horses. Nine horses participated in the study; that was approved by the University Animal Care and Use Committee. One thoracic limb or one pelvic limb of each horse was randomly selected. After the veins were catheterized, an Esmarch bandage tourniquet was applied and the catheter was injected with a solution containing 500mg of imipenem. Synovial fluid samples were collected from the fetlock joint and blood samples were collected from the jugular vein. All samples were analyzed for imipenem concentration using liquid chromatography mass spectrometry. Cmax of imipenem in the fetlock joint using the cephalic and the saphenous vein was 87 and 60μg⁄mL, respectively. The results indicate that by performing IV-RLP using the cephalic/saphenous, one can achieve imipenem concentrations in the fetlock joint that are well above the MIC of most susceptible pathogens including resistant bacteria such as Methicillin Resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Thus, with selective; judicious use, RLP with imipenem can markedly increase treatment efficacy of severe distal limb infections in horses.

Rationale for eliminating Staphylococcus breakpoints for β-lactam agents other than penicillin, oxacillin or cefoxitin, and ceftaroline

Due to the ongoing concern about the reliability of Staphylococcus breakpoints (interpretive criteria) for other β-lactam agents, the Clinical and Laboratory Standards Institute recently approved the elimination of all breakpoints for antistaphylococcal β-lactams except for penicillin, oxacillin or cefoxitin, and ceftaroline. Routine testing of penicillin and oxacillin or cefoxitin should be used to infer susceptibility for all β-lactams with approved clinical indications for staphylococcal infections. It is critical for laboratories to reject requests for susceptibility testing of other β-lactams against staphylococci and to indicate that susceptibility to these agents can be predicted from the penicillin and oxacillin or cefoxitin results. This article reviews β-lactam resistance mechanisms in staphylococci, current antimicrobial susceptibility testing and reporting recommendations for β-lactams and staphylococci, and microbiologic data and clinical data supporting the elimination of staphylococcal breakpoints for other β-lactam agents.

A phase 3 randomized double-blind comparison of ceftobiprole medocaril versus ceftazidime plus linezolid for the treatment of hospital-acquired pneumonia

BACKGROUND

Ceftobiprole, the active moiety of ceftobiprole medocaril, is a novel broad-spectrum cephalosporin, with bactericidal activity against a wide range of gram-positive bacteria, including Staphylococcus aureus (including methicillin-resistant strains) and penicillin- and ceftriaxone-resistant pneumococci, and gram-negative bacteria, including Enterobacteriaceae and Pseudomonas aeruginosa.

METHODS

This was a double-blind, randomized, multicenter study of 781 patients with hospital-acquired pneumonia (HAP), including 210 with ventilator-associated pneumonia (VAP). Treatment was intravenous ceftobiprole 500 mg every 8 hours, or ceftazidime 2 g every 8 hours plus linezolid 600 mg every 12 hours; primary outcome was clinical cure at the test-of-cure visit.

RESULTS

Overall cure rates for ceftobiprole vs ceftazidime/linezolid were 49.9% vs 52.8% (intent-to-treat [ITT], 95% confidence interval [CI] for the difference, -10.0 to 4.1) and 69.3% vs 71.3% (clinically evaluable [CE], 95% CI, -10.0 to 6.1). Cure rates in HAP (excluding VAP) patients were 59.6% vs 58.8% (ITT, 95% CI, -7.3 to 8.8), and 77.8% vs 76.2% (CE, 95% CI, -6.9 to 10.0). Cure rates in VAP patients were 23.1% vs 36.8% (ITT, 95% CI, -26.0 to -1.5) and 37.7% vs 55.9% (CE, 95% CI, -36.4 to 0). Microbiological eradication rates in HAP (excluding VAP) patients were, respectively, 62.9% vs 67.5% (microbiologically evaluable [ME], 95% CI, -16.7 to 7.6), and in VAP patients 30.4% vs 50.0% (ME, 95% CI, -38.8 to -0.4). Treatment-related adverse events were comparable for ceftobiprole (24.9%) and ceftazidime/linezolid (25.4%).

CONCLUSIONS

Ceftobiprole is a safe and effective bactericidal antibiotic for the empiric treatment of HAP (excluding VAP). Further investigations are needed before recommending the use of ceftobiprole in VAP patients. Clinical Trials Registration. NCT00210964, NCT00229008.

Necrotizing pneumonia due to femoral osteomyelitis caused by community-acquired methicillin-resistant Staphylococcus aureus

A chest X-ray of a young healthy African-American man with acute respiratory failure revealed bilateral multiple nodular shadows in the lungs, while community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was detected in blood and sputum cultures. Magnetic resonance imaging showed osteomyelitis of the left thigh, and computed tomography revealed bilateral cavitary lesions in the chest, indicating necrotizing pneumonia with pulmonary embolism caused by osteomyelitis as a result of infection with CA-MRSA. CA-MRSA should be suspected as a causative agent of severe community-acquired pneumonia, even in Japan, among patients who belong to communities at high risk of CA-MRSA infection.