Newer beta-lactam antibiotics: doripenem, ceftobiprole, ceftaroline, and cefepime

Development of cefepime-induced encephalopathy in a patient with depression and rectal cancer: A case report

BACKGROUND

Cefepime, a fourth-generation cephalosporin, has neurotoxic side effects such as encephalopathy. Baseline conditions, including blood-brain barrier (BBB) impairment and renal dysfunction, are known to associate with elevated central nervous concentration of cefepime. Although BBB dysfunction occurs with depression or cancer, currently, neither is regarded as a risk factor for cefepime-induced encephalopathy.

CASE PRESENTATION

A 79-year-old woman with a history of depression and rectal cancer was hospitalized for a bacterial liver abscess. Brain metastasis and other causes for delirium were excluded, and no renal dysfunction was observed. However, 11 days after cefepime and metronidazole administration, the patient suddenly developed confusion, disorientation, and myoclonus, with no apparent changes on brain magnetic resonance imaging. Electroencephalography revealed a consistent tri-phasic wave pattern. Clinical symptoms were well consistent with cefepime-induced encephalopathy; hence, cefepime and metronidazole were discontinued, followed by rapid physical and mental recovery, with no aftereffects.

CONCLUSIONS

In terms of BBB dysfunction, depression and cancer might be possible occult risk factors for cefepime-induced encephalopathy. Doctors need to pay attention to encephalopathy risk when administering cefepime in patients with depression or cancer because the psychiatric symptoms of encephalopathy, depression, and delirium from other causes are often confusing, leading to misdiagnosis and a poor prognosis.

Carbapenem Resistance Associated with Coliuria among Outpatient and Hospitalized Urology Patients

The World Health Organization in 2017 listed carbapenem resistant Enterobacteriaceae (CRE) with critical priority for research. A research to assess carbapenem resistant Escherichia coli (CREc) in coliuria among the outpatients and inpatients of a tertiary health institution was carried out using conventional methods, polymerase chain reaction, Sanger sequencing, and bioinformatics. There were 39 positive coliuria cases from the urine samples collected from a total of 126 patients with various genitourinary diseases. The E. coli enumeration (log₁₀ CFU/mL) revealed that 82.1% (n = 32) of the samples showed significant coliuria, 12.8% (n = 5) showed non-significant coliuria while 5.1% (n = 2) showed indeterminate coliuria even when repeated. Significantly higher numbers (p > 0.05) of the sampled inpatients yielded positive coliuria (57.9%) than the outpatients. Though there were significantly more (P > 0.05) urology female patients (n = 77) than male (n = 49), coliuria was more prevalent in sampled male patients (34.9%) than female (28.6%). Highest prevalence of coliuria was observed among the age range (18–30) years. Selected CREc that was sequenced and the sequences submitted to GenBank of National Center for Biotechnological Information (NCBI) were Escherichia coli AYO-WINI111 and Escherichia coli AYO-WINI112 with accession number MT735391 and MT735392, respectively. High resistance was observed against ertapenem (53%), imipenem (62%), meropenem (48%), and doripenem (47%), while 7%–22% of the isolates showed phenotypic intermediate carbapenem resistance. Critically dangerous CREc are harboured by large number urology patients in the study area, depicting the need for more attention in the management of the condition, as CREc are close to achieving totally antibiotic resistance.

OUP accepted manuscript

Objectives

To describe the therapeutic drug monitoring (TDM) of cefepime in non-critically ill adults and compare four different ways of dosing: conventional table-based; empirically adjusted following TDM; individualized based on a population pharmacokinetic (PopPK) model without TDM; and TDM-adjusted with a Bayesian approach integrating TDM and PopPK.

Methods

We conducted a retrospective study in a tertiary centre to examine the current practice of TDM and to evaluate the potential for improvement by PopPK-based software individualization. The prediction of trough concentrations and the total daily doses (TDD) prescribed according to each approach were compared by calculating the mean logarithmic bias and the root mean squared error, complemented by linear regression and variance analysis.

Results

Among 168 trough concentrations in 119 patients (median: 12 mg/L), 38.6% of measurements exceeded 15 mg/L, the reported threshold for neurotoxicity. Nine patients developed neurotoxicity. The prediction performance of PopPK alone for trough concentrations was moderate, but clearly improved after integration of TDM. Accordingly, TDD were significantly lower for a priori PopPK-based dosage (mean: 2907 mg/24 h) compared with actual table-based dosage (4625 mg/24 h, P < 0.001). They were also lower for a posteriori dosage based on PopPK and TDM (3377 mg/24 h) compared with actual dosage after empirical TDM (4233 mg/24 h, P < 0.001), as model-based adjustment privileged more frequent administrations.

Conclusions

Our observations support routine TDM of cefepime to prevent overdosing and subsequent toxicity in the non-critically ill. Software-based individualization seems promising to optimize the benefits of TDM, but has little potential to replace it.

Ceftaroline versus vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) in an experimental MRSA meningitis model

OBJECTIVES

The aim of this study was to compare the antibacterial activity of ceftaroline versus vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) meningitis in an experimental rabbit meningitis model.

METHODS

The antibacterial activity of ceftaroline was compared with vancomycin in the treatment of meningitis induced by MRSA strain ATCC 43300 in an experimental rabbit meningitis model. Quantitative cerebrospinal fluid (CSF) cultures were performed at the beginning of antibiotic treatment and 24h and 73h after the first antibiotic dose. Furthermore, in vitro time-kill data were investigated at 0, 2, 4, 6, 8, 12 and 24h in sterile human serum.

RESULTS

The difference between the control group versus both treatment groups was significant when comparing the decrease in colony counts in CSF both at 24h and 73h after the first antibiotic dose (P<0.05). At the end of the experiment, there was a significant difference in survival between both the ceftaroline-treated group and the vancomycin-treated group versus the control group, but not between the two treatment groups.

CONCLUSION

These results suggest that the antibacterial activity of both ceftaroline and vancomycin are similar in the treatment of MRSA meningitis in an experimental rabbit meningitis model.

Promising antibacterial agents against multidrug resistant Staphylococcus aureus

Rapid emergence of multidrug resistant Staphylococcus aureus infections has created a critical health menace universally. Resistance to all the available chemotherapeutics has been on rise which led to WHO to stratify Staphylococcus aureus as high tier priorty II pathogen. Hence, discovery and development of new antibacterial agents with new mode of action is crucial to address the multidrug resistant Staphylococcus aureus infections. The egressing understanding of new antibacterials on their biological target provides opportunities for new therapeutic agents. This review underlines on various aspects of drug design, structure activity relationships (SARs) and mechanism of action of various new antibacterial agents and also covers the recent reports on new antibacterial agents with potent activity against multidrug resistant Staphylococcus aureus. This review provides attention on in vitro and in vivo pharmacological activities of new antibacterial agents in the point of view of drug discovery and development.

Synthesis and evaluation of new quinazolin-4(3H)-one derivatives as potent antibacterial agents against multidrug resistant Staphylococcus aureus and Mycobacterium tuberculosis

Staphylococcus aureus and Mycobacterium tuberculosis are major causative agents responsible for serious nosocomial and community-acquired infections impacting healthcare systems globally. Over several decades, these pathogens have developed resistance to multiple antibiotics significantly affecting morbidity and mortality. Thus, these recalcitrant pathogens are amongst the most formidable microbial pathogens for which international healthcare agencies have mandated active identification and development of new antibacterial agents for chemotherapeutic intervention. In our present work, a series of new quinazolin-4(3H)-one derivatives were designed, synthesized and evaluated for their antibacterial activity against ESKAP pathogens and pathogenic mycobacteria. The experiments revealed that 4'c, 4'e, 4'f and 4'h displayed selective and potent inhibitory activity against Staphylococcus aureus with MIC values ranging from 0.03-0.25 μg/mL. Furthermore, compounds 4'c and 4'e were found to be benign to Vero cells (CC₅₀ = >5 μg/mL) and displayed promising selectivity index (SI) > 167 and > 83.4 respectively. Additionally, 4'c and 4'e demonstrated equipotent MIC against multiple drug-resistant strains of S. aureus including VRSA, concentration dependent bactericidal activity against S. aureus and synergized with FDA approved drugs. Moreover, compound 4'c exhibited more potent activity in reducing the biofilm and exhibited a PAE of ∼2 h at 10X MIC which is comparable to levofloxacin and vancomycin. In vivo efficacy of 4'c in murine neutropenic thigh infection model revealed that 4'c caused a similar reduction in cfu as vancomycin. Gratifyingly, compounds 4d, 4e, 9a, 9b, 14a, 4'e and 4'f also exhibited anti-mycobacterial activity with MIC values in the range of 2-16 μg/mL. In addition, the compounds were found to be less toxic to Vero cells (CC₅₀ = 12.5->100 μg/mL), thus displaying a favourable selectivity index. The interesting results obtained here suggest the potential utilization of these new quinazolin-4(3H)-one derivatives as promising antibacterial agents for treating MDR-Staphylococcal and mycobacterial infections.

4(3H)-Quinazolinone derivatives: Promising antibacterial drug leads

Emergence of drug resistance has created unmet medical need for the development of new classes of antibiotics. Discovery of new antibacterial agents with new mode of action remains a high priority universally. 4(3H)-quinazolinone, a fused nitrogen heterocyclic compound has emerged as a biologically privileged structure, possessing a wide range of biological properties viz. anticancer, antibacterial, antitubercular, antifungal, anti-HIV, anticonvulsant, anti-inflammatory and analgesic activities. Promising antibacterial properties of quinazolinones have enthused the medicinal chemists to explore and develop this fused heterocyclic system for new antibacterial agents. Utilization of quinazolinone core for the design and synthesis of new antibacterial agents has recently gained momentum. This review aims to provide an overview of the structures and antibacterial activity of various 4(3H)-quinazolinone derivatives covering various aspects of in vitro and in vivo pharmacological activities and structure activity relationships (SARs).

Cefepime-induced Neurotoxicity: Five Cases Reported in a Single Institution

Cefepime is a fourth-generation cephalosporin widely used to treat gram-positive and gram-negative infections. Its half-life is approximately two hours in patients with normal renal function and may increase to 13.5 hours in patients with acutely or chronically impaired renal function. Although dosage adjustment is recommended for patients with renal insufficiency to prevent drug accumulation, toxicity has been reported in patients even with normal renal function. One underreported complication of cefepime toxicity is cefepime-induced encephalopathy (CIE). While the pathophysiology is unclear, treatment involves early discontinuation of this antibiotic to decrease morbidity and mortality. We report five cases of cefepime-induced encephalopathy occurring within one year at a single institution.

Synthesis of 1,2,3-triazole linked 4(3H)-Quinazolinones as potent antibacterial agents against multidrug-resistant Staphylococcus aureus

Methicillin and vancomycin resistant Staphylococcus aureus infections are an emerging global health concern leading to increasing morbidity and mortality. Continuous increase in drug resistance has underlined the need for discovery and development of new antibacterial agents acting via novel mechanisms to overcome this pressing issue. In this context, a number of 1,2,3-triazole linked 4(3H)-quinazolinone derivatives were designed and synthesized as potent antibacterial agents. When evaluated against ESKAP pathogen panel, compounds 7a, 7b, 7c, 7e, 7f, 7g, 7h, 7i, 9a, 9c, 9d and 9e exhibited significantly selective inhibitory activities towards Staphylococcus aureus (MIC = 0.5-4 μg/mL). To understand and confirm the specificity of these compounds, the compounds 7a and 9a were tested against E. coli and A. baumannii in combination with sub-lethal concentrations of Polymyxin B nonapeptide (PMBN) and were found to be inactive. This clearly indicated that these compounds possess specific and potent activity towards S. aureus and are inactive against gram-negative pathogens. Encouragingly, the compounds were also found to be non toxic to Vero cells and displayed favourable selectivity index (SI = 40 to 80). Furthermore, 7a and 9a were found to possess potent inhibitory activity when tested against multidrug resistant S. aureus including strains resistant to vancomycin (MIC values 0.5-32 μg/mL), indicating that the compounds are able to escape current drug-resistance mechanisms. With the potent anti-bacterial activity exhibited the new series of 1,2,3-triazole linked 4(3H)-quinazolinones have emerged as promising candidates for treating multidrug resistant Staphylococcus aureus infections.

Pharmacokinetic/pharmacodynamic parameters for treatment optimization of infection due to antibiotic resistant bacteria: a summary for practical purposes in children and adults

In the last years, there has been a tremendous increase in the incidence of bacterial infections due to resistant strains, especially multi-drug resistant Gram-negative bacilli. In Europe, a north to south and a west to east gradient was noticed, with more than one third of the K. pneumonia isolates being resistant to carbapenems in few countries. New antibiotics are lacking and, as a consequence, pharmacokinetic/pharmacodynamic parameters, normalized to pathogen minimal inhibitory concentration, are used with increased frequency to treat infections due to difficult-to-treat pathogens. These parameters are available at least for the adult population, but sparse in many different publications. This review wants to provide a comprehensive and 'easy to read' text for everyday practice, briefly summarizing the presently available knowledge on pharmacokinetic/pharmacodynamic parameters (normalized for minimal inhibitory concentration values) of different class drugs, that can be applied for an effective antibacterial treatment infections due to antibiotic-resistant pathogens.

Characterizing Cefepime Neurotoxicity: A Systematic Review

Neurotoxicity due to cefepime has not been well characterized. We performed a systematic review of the literature and included 5 additional cases from our center. Of the 198 cases found, the mean age was 67 years and 87% of patients had renal dysfunction. The most common clinical features were diminished level of consciousness (80%), disorientation/agitation (47%), and myoclonus (40%). It is worth noting that nonconvulsive status epilepticus was relatively common with 31% of cases, whereas only 11% had convulsive seizures. Single-center estimate of incidence was 1 in 480 courses of cefepime. Cefepime neurotoxicity should be considered in older patients with renal dysfunction and new onset encephalopathy, especially if concurrent myoclonus is present. More work is needed to prospectively assess incidence and outcomes related to cefepime neurotoxicity.

Empiric Antibiotic Therapy of Nosocomial Bacterial Infections

Broad-spectrum antibiotics are commonly used by physicians to treat various infections. The source of infection and causative organisms are not always apparent during the initial evaluation of the patient, and antibiotics are often given empirically to patients with suspected sepsis. Fear of attempting cephalosporins and carbapenems in penicillin-allergic septic patients may result in significant decrease in the spectrum of antimicrobial coverage. Empiric antibiotic therapy should sufficiently cover all the suspected pathogens, guided by the bacteriologic susceptibilities of the medical center. It is important to understand the major pharmacokinetic properties of antibacterial agents for proper use and to minimize the development of resistance. In several septic patients, negative cultures do not exclude active infection and positive cultures may not represent the actual infection. This article will review the important differences in the spectrum of commonly used antibiotics for nosocomial bacterial infections with a particular emphasis on culture-negative sepsis and colonization.

Iatrogenic neurology

Iatrogenic disease is one of the most frequent causes of hospital admissions and constitutes a growing public health problem. The most common type of iatrogenic neurologic disease is pharmacologic, and the central and peripheral nervous systems are particularly vulnerable. Despite this, iatrogenic disease is generally overlooked as a differential diagnosis among neurologic patients. The clinical picture of pharmacologically mediated iatrogenic neurologic disease can range from mild to fatal. Common and uncommon forms of drug toxicity are comprehensively addressed in this chapter. While the majority of neurologic adverse effects are listed and referenced in the tables, the most relevant issues are further discussed in the text.

Carbapenem-resistant Enterobacteriaceae: a menace to our most vulnerable patients

The emergence of carbapenem-resistant Enterobacteriaceae (CRE) highlights the importance of effective antibiotics to maintain the safety of our health care system. Clinicians will encounter CRE as a cause of difficult-to-treat and often fatal infections in hospitalized patients. We review the mechanisms of carbapenem resistance, the dissemination and clinical impact of these resistant organisms, and challenges to their detection, treatment, and control.

Neurotoxic effects associated with antibiotic use: management considerations

The clinical manifestations of antibiotic-induced neurotoxic effects, the underlying mechanisms and management strategies have been reviewed. PubMed and OVID searches (January 1960-June 2010) were conducted using search terms such as antibiotics, side effects, neurotoxicity and encephalopathy which yielded approximately 300 articles. All relevant case reports, case series, letters and retrospective reviews describing neurotoxic effects and those discussing mechanisms of neurotoxicity were included. Antibiotic-induced neurotoxic side effects can have a myriad of neurologic presentations. Patients with prior central nervous system (CNS) disease, renal insufficiency and advanced age may be particularly vulnerable. Treatment consists of discontinuation of the offending agent, use of antiepileptic drugs in the case of seizures or status epilepticus and haemodialysis in certain cases. The risk of CNS toxicity may be reduced via dosage adjustments in high risk populations. Awareness of the potential neurotoxic clinical manifestations of various antibiotics and high degree of vigilance in critically ill patients is essential in identifying a potentially serious, though reversible complications of antibiotic therapy particularly with the advent of newer antimicrobial agents.

Comparative ceftaroline activity tested against pathogens associated with community-acquired pneumonia: results from an international surveillance study

OBJECTIVES

To document the spectrum of activity of ceftaroline, the active form of the prodrug, ceftaroline fosamil, a new cephalosporin with anti-methicillin-resistant staphylococcal activity, against a surveillance collection of clinical isolates obtained from the USA and Europe during 2008-09.

METHODS

A selected group of species associated with community-acquired pneumonia (CAP; 6496 of 17 326 monitored strains) were tested for susceptibility in a central laboratory using CLSI broth microdilution methods. Organisms were sampled from 55 medical centres, 27 in the USA and 28 (12 countries) in Europe. Ceftaroline and comparator agents were tested and interpretations of MIC endpoints made by applying current CLSI (2010) and EUCAST (2010) breakpoint criteria.

RESULTS

Against 1340 Streptococcus pneumoniae, ceftaroline inhibited all isolates at ≤0.5 mg/L (MIC(50/90), ≤0.008/0.12 mg/L) and was 8-fold more active than ceftriaxone (MIC(90), 1 mg/L; only 79.2% coverage at EUCAST breakpoint). Haemophilus influenzae (n = 584; MIC(50/90), ≤0.008/0.015 mg/L), Moraxella catarrhalis (n = 377; MIC(50/90), 0.03-0.06/0.12 mg/L) and Staphylococcus aureus (n = 590; MIC(50/90), 0.5/1 mg/L) were very susceptible to ceftaroline, regardless of β-lactamase production or multidrug resistance (MDR) patterns. The potency of ceftaroline against three species of Enterobacteriaceae (Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae) was similar to that of ceftriaxone, ceftazidime and piperacillin/tazobactam. Only modest differences in rates of ceftaroline susceptibility (breakpoint ≤2 mg/L) were noted with extended-spectrum β-lactamase-negative Enterobacteriaceae strains between the USA and Europe (97.9% versus 97.0% for E. coli). Ceftaroline, like ceftriaxone, was not active against ceftazidime-resistant E. coli (10.2%-26.2% susceptible at ≤2 mg/L) or K. pneumoniae (5.3%-11.2%).

CONCLUSIONS

The ceftaroline surveillance for 2008-09 (USA and Europe) documented low MIC(50/90) values for S. aureus isolates at 0.5/1 and 0.25/1 mg/L, respectively. More importantly, ceftaroline MIC(90) results for S. pneumoniae (0.12 mg/L), H. influenzae (0.015 mg/L) and M. catarrhalis (0.12 mg/L) were very low, all MICs being ≤0.5 mg/L. Ceftaroline exhibited promising high potency and wide coverage against Gram-positive and -negative pathogens known to cause CAP, especially isolates of MDR pneumococci and methicillin-resistant S. aureus.

Microtiter plate-based assay for inhibitors of penicillin-binding protein 2a from methicillin-resistant Staphylococcus aureus

Penicillin-binding protein 2a (PBP2a), the molecular determinant for high-level β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA), is intrinsically resistant to most β-lactam antibiotics. The development and characterization of new inhibitors targeting PBP2a would benefit from an effective and convenient assay for inhibitor binding. This study was directed toward the development of a fluorescently detected β-lactam binding assay for PBP2a from MRSA. Biotinylated ampicillin and biotinylated cephalexin were tested as tagging reagents for fluorescence detection by using a streptavidin-horseradish peroxidase conjugate. Both bound surprisingly well to PBP2a, with binding constants of 1.6 ± 0.4 μM and 13.6 ± 0.8 μM, respectively. Two forms of the assay were developed, a one-step direct competition form of the assay and a two-step indirect competition form of the assay, and both forms of the assay gave comparable results. This assay was then used to characterize PBP2a binding to ceftobiprole, which gave results consistent with previous studies of ceftobiprole-PBP2a binding. This assay was also demonstrated for screening for PBP2a inhibitors by screening a set of 13 randomly selected β-lactams for PBP2a inhibition at 750 μM. Meropenem was observed to give substantial inhibition in this screen, and a follow-up titration experiment determined its apparent K(i) to be 480 ± 70 μM. The availability of convenient and sensitive microtiter-plate based assays for the screening and characterization of PBP2a inhibitors is expected to facilitate the discovery and development of new PBP2a inhibitors for use in combating the serious public health problem posed by MRSA.

Ceftaroline: A New Cephalosporin with Activity against Methicillin-Resistant Staphylococcus aureus (MRSA)

Microbial resistance has reached alarming levels, threatening to outpace the ability to counter with more potent antimicrobial agents. In particular, methicillin-resistant Staphylococcus aureus (MRSA) has become a leading cause of skin and soft-tissue infections and PVL-positive strains have been associated with necrotizing pneumonia. Increasing reports of growing resistance to glycopeptides have been noted, further limiting the efficacy of standard antibiotics, such as vancomycin. Ceftaroline is a novel fifth-generation cephalosporin, which exhibits broad-spectrum activity against Gram-positive bacteria, including MRSA and extensively-resistant strains, such as vancomycin-intermediate S. aureus (VISA), heteroresistant VISA (hVISA), and vancomycin-resistant S. aureus (VRSA). In addition to being an exciting new agent in the anti-MRSA armamentarium, ceftaroline provides efficacy against many respiratory pathogens including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Ceftaroline (600 mg intravenously every 12 hours) has been shown effective in phase III studies in the treatment of complicated skin and soft tissue infections and community-acquired pneumonia. To date, this unique antibiotic exhibits a low propensity for inducing resistance and has a good safety profile, although further post-marketing data and clinical experience are needed. In summary, ceftaroline provides an additional option for the management of complex multidrug resistant infections, including MRSA.