Ceftaroline: a novel cephalosporin with activity against methicillin-resistant Staphylococcus aureus

The Home Environment Is a Reservoir for Methicillin-Resistant Coagulase-Negative Staphylococci and Mammaliicocci

Coagulase-negative staphylococci (CoNS) and mammaliicocci are opportunistic human and animal pathogens, often resistant to multiple antimicrobials, including methicillin. Methicillin-resistant CoNS (MRCoNS) have traditionally been linked to hospitals and healthcare facilities, where they are significant contributors to nosocomial infections. However, screenings of non-hospital environments have linked MRCoNS and methicillin-resistant mammaliicocci (MRM) to other ecological niches. The aim of this study was to explore the home environment as a reservoir for MRCoNS and MRM. A total of 33 households, including households with a dog with a methicillin-resistant staphylococcal infection, households with healthy dogs or cats and households without pets, were screened for MRCoNS and MRM by sampling one human, one pet (if present) and the environment. Samples were analyzed by a selective culture-based method, and bacterial species were identified by MALDI-TOF MS and tested for antibiotic susceptibility by the agar disk diffusion method. Following whole-genome sequencing, a large diversity of SCCmec elements and sequence types was revealed, which did not indicate any clonal dissemination of specific strains. Virulome and mobilome analyses indicated a high degree of species specificity. Altogether, this study documents that the home environment is a reservoir for a variety of MRCoNS and MRM regardless of the type of household.

Ceftaroline for Central Nervous System Infections: Case Report of a Young Infant, and Scoping Review

BACKGROUND

Managing health care acquired and device-associated intracranial infections in young children can be challenging given adverse antibiotic side effects and difficulties in achieving adequate central nervous system (CNS) antibiotic concentrations. Ceftaroline is a cephalosporin with a favorable safety profile and activity against methicillin-resistant Staphylococci and several Gram-negative organisms. Published data on the use of ceftaroline for CNS infections in children and adults are limited.

METHODS

We describe a 2-month-old infant with ventriculo-subgaleal shunt-associated methicillin-resistant Staphylococcus epidermidis ventriculitis, which was successfully treated with ceftaroline, in addition to vancomycin and rifampin. We conducted a scoping review of English-language literature retrieved from PubMed, EMBASE and Web of Science that assessed the use of ceftaroline for CNS infections.

RESULTS

We identified 22 articles for inclusion in our review, which described 92 unique patients, of whom 2 were <21 years old. Ceftaroline was commonly used in conjunction with other antibiotics to treat infections caused by Staphylococcus aureus, coagulase-negative Staphylococci and Streptococcus pneumoniae. Most case reports described clinical success with ceftaroline, though small case series and cohort studies yielded mixed efficacy assessments. Adverse effects attributed to ceftaroline were rare and included reversible myelosuppression, eosinophilia, hepatotoxicity and nephrotoxicity. Pharmacokinetic/pharmacodynamic studies suggested similar CNS penetration through inflamed meninges as other beta lactam antibiotics.

CONCLUSIONS

We identified a growing body of published evidence supporting the use of ceftaroline in combination with other agents for the treatment of CNS infections. In absence of clinical trials, additional real-world data are needed to define the efficacy and safety of ceftaroline for children and adults with CNS infections.

Cephalosporin resistance, tolerance, and approaches to improve their activities

Cephalosporins comprise a β-lactam antibiotic class whose first members were discovered in 1945 from the fungus Cephalosporium acremonium. Their clinical use for Gram-negative bacterial infections is widespread due to their ability to traverse outer membranes through porins to gain access to the periplasm and disrupt peptidoglycan synthesis. More recent members of the cephalosporin class are administered as last resort treatments for complicated urinary tract infections, MRSA, and other multi-drug resistant pathogens, such as Neisseria gonorrhoeae. Unfortunately, there has been a global increase in cephalosporin-resistant strains, heteroresistance to this drug class has been a topic of increasing concern, and tolerance and persistence are recognized as potential causes of cephalosporin treatment failure. In this review, we summarize the cephalosporin antibiotic class from discovery to their mechanisms of action, and discuss the causes of cephalosporin treatment failure, which include resistance, tolerance, and phenomena when those qualities are exhibited by only small subpopulations of bacterial cultures (heteroresistance and persistence). Further, we discuss how recent efforts with cephalosporin conjugates and combination treatments aim to reinvigorate this antibiotic class.

Antibiotic Resistance to Molecules Commonly Prescribed for the Treatment of Antibiotic-Resistant Gram-Positive Pathogens: What Is Relevant for the Clinician?

Antibiotic resistance in Gram-positive pathogens is a relevant concern, particularly in the hospital setting. Several antibiotics are now available to treat these drug-resistant pathogens, such as daptomycin, dalbavancin, linezolid, tedizolid, ceftaroline, ceftobiprole, and fosfomycin. However, antibiotic resistance can also affect these newer molecules. Overall, this is not a frequent phenomenon, but it is a growing concern in some settings and can compromise the effectiveness of these molecules, leaving few therapeutic options. We reviewed the available evidence about the epidemiology of antibiotic resistance to these antibiotics and the main molecular mechanisms of resistance, particularly methicillin-resistant Sthaphylococcus aureus, methicillin-resistant coagulase-negative staphylococci, vancomycin-resistant Enterococcus faecium, and penicillin-resistant Streptococcus pneumoniae. We discussed the interpretation of susceptibility tests when minimum inhibitory concentrations are not available. We focused on the risk of the emergence of resistance during treatment, particularly for daptomycin and fosfomycin, and we discussed the strategies that can be implemented to reduce this phenomenon, which can lead to clinical failure despite appropriate antibiotic treatment. The judicious use of antibiotics, epidemiological surveillance, and infection control measures is essential to preserving the efficacy of these drugs.

A Review on Five and Six-Membered Heterocyclic Compounds Targeting the Penicillin-Binding Protein 2 (PBP2A) of Methicillin-Resistant Staphylococcus aureus (MRSA)

Staphylococcus aureus is a common human pathogen. Methicillin-resistant Staphylococcus aureus (MRSA) infections pose significant and challenging therapeutic difficulties. MRSA often acquires the non-native gene PBP2a, which results in reduced susceptibility to β-lactam antibiotics, thus conferring resistance. PBP2a has a lower affinity for methicillin, allowing bacteria to maintain peptidoglycan biosynthesis, a core component of the bacterial cell wall. Consequently, even in the presence of methicillin or other antibiotics, bacteria can develop resistance. Due to genes responsible for resistance, S. aureus becomes MRSA. The fundamental premise of this resistance mechanism is well-understood. Given the therapeutic concerns posed by resistant microorganisms, there is a legitimate demand for novel antibiotics. This review primarily focuses on PBP2a scaffolds and the various screening approaches used to identify PBP2a inhibitors. The following classes of compounds and their biological activities are discussed: Penicillin, Cephalosporins, Pyrazole-Benzimidazole-based derivatives, Oxadiazole-containing derivatives, non-β-lactam allosteric inhibitors, 4-(3H)-Quinazolinones, Pyrrolylated chalcone, Bis-2-Oxoazetidinyl macrocycles (β-lactam antibiotics with 1,3-Bridges), Macrocycle-embedded β-lactams as novel inhibitors, Pyridine-Coupled Pyrimidinones, novel Naphthalimide corbelled aminothiazoximes, non-covalent inhibitors, Investigational-β-lactam antibiotics, Carbapenem, novel Benzoxazole derivatives, Pyrazolylpyridine analogues, and other miscellaneous classes of scaffolds for PBP2a. Additionally, we discuss the penicillin-binding protein, a crucial target in the MRSA cell wall. Various aspects of PBP2a, bacterial cell walls, peptidoglycans, different crystal structures of PBP2a, synthetic routes for PBP2a inhibitors, and future perspectives on MRSA inhibitors are also explored.

National surveillance of antimicrobial susceptibilities to ceftaroline, dalbavancin, telavancin, tedizolid, eravacycline, omadacycline, and other comparator antibiotics, and genetic characteristics of bacteremic Staphylococcus aureus isolates in adults: Results from the Surveillance of Multicenter Antimicrobial Resistance in Taiwan (SMART) program in 2020

Methicillin-resistant Staphylococcus aureus (MRSA) causes invasive infections and is associated with community-acquired infections (CAIs) and hospital-associated infections (HAIs). In 2020, 315 S. aureus isolates, including 145 methicillin-susceptible S. aureus (MSSA) and 170 MRSA, mainly associated with bacteremia and mostly CAIs, were collected from 16 hospitals in different regions of Taiwan. Minimum inhibitory concentrations (MICs) were determined using the Sensititre™ complete automated AST system. Staphylococcal cassette chromosome mec (SCCmec) types were analysed using multiplex polymerase chain reaction. The median age of patients infected with MRSA was significantly higher than that of patients infected with MSSA (72.5 years vs. 67.0 years, P=0.027). MIC₅₀/MIC₉₀ values of eravacycline and omadacycline were 0.06/0.12, and 0.25/0.5, respectively. Of the MRSA isolates, 4.1% presented susceptible dose-dependence to ceftaroline, most of which (85.7%) were HAI- and Panton-Valentine leukocidin (PVL)-negative. Among the MRSA isolates, 7.1% were not susceptible to telavancin and tedizolid (mainly type IV, PVL-negative, and CAI), 0.6% were not susceptible to daptomycin (type III, PVL-negative, and HAI), and 1.8% were not susceptible to quinupristin/dalfopristin (three isolates were type III, IV, and V_T, respectively, and all were PVL-negative), but all were susceptible to dalbavancin. In conclusion, patients with bacteremia caused by MRSA were older than those with bacteremia caused by MSSA, SCCmec type IV was more predominant in CAI than in HAI, and MRSA isolates not susceptible to novel anti-MRSA antimicrobials belonged to types II, III, or IV. Further studies that include comprehensive demographics and more detailed descriptions of other antimicrobial-resistant genes are urgently needed.

Urgent need for novel antibiotics in Republic of Korea to combat multidrug-resistant bacteria

Multidrug resistance in bacteria is an important issue and is increasing in frequency worldwide because of the limitations of therapeutic agents. From 2010 to 2019, 14 new systemic antibiotics received regulatory approval in the United States. However, few new antibiotics have been introduced in Republic of Korea to combat multidrug-resistant pathogens. Here, we introduce six novel antibiotics for Gram-positive bacteria and five for Gram-negative bacteria approved by the United States Food and Drug Administration and the European Medicines Agency from 2009 to October 2021, and recommend that they be approved for use in Republic of Korea at the earliest possible date.

Ceftaroline Dosage Optimized for Pediatric Patients With Renal Impairment Using Physiologically Based Pharmacokinetic Modeling

Ceftaroline fosamil is a fifth-generation cephalosporin approved as a treatment for adults and children with community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections. However, its pharmacokinetics have not been fully evaluated in children with renal impairment. This study aimed to propose proper ceftaroline dosages optimized for the renally impaired pediatric population using physiologically based pharmacokinetic (PBPK) modeling. A PBPK model of ceftaroline was established and verified to simulate its disposition in the healthy population and renally impaired adults and to predict the exposure in renally impaired pediatric patients. Consistency was confirmed between simulated and observed data after intravenous administration of various ceftaroline regimens; fold errors were within the 2-fold error range. Among 6-year-old children, healthy subjects had 1.5-fold, 2-fold, and 2.6-fold lower areas under the plasma concentration-time curve (AUCs) than the moderate, severe, and end-stage renally impaired patient groups, respectively; among 1-year-old children, healthy subjects had 1.5-fold, 2.1-fold, and 2.5-fold lower AUCs than the respective renally impaired patient groups; among 1-month-old children, healthy subjects had 1.5-fold, 1.8-fold, and 2.2-fold lower AUCs than the respective renally impaired patient groups. The proposed dosage should be adjusted to 8, 6, and 5 mg/kg every 8 hours for patients aged ≥2 years to <18 years (≤33 kg) with moderate, severe, and end-stage renal impairment, respectively; 5, 4, and 3 mg/kg every 8 hours for patients aged 2 months to <2 years with moderate, severe, and end-stage renal impairment, respectively; 4, 3.5, and 2.5 mg/kg every 8 hours for patients 0 to <2 months of age with moderate, severe, and end-stage renal impairment, respectively. Furthermore, pharmacodynamic investigations demonstrated that adequate antimicrobial effects were attained at the proposed doses in 3 age groups. Hence, our PBPK model can be an effective tool to support ceftaroline dosage proposals for renally impaired pediatric patients.

Bilateral Endogenous Methicillin-Resistant Staphylococcus aureus Endophthalmitis in a Young Athlete: A Story of Full Recovery

Endogenous endophthalmitis (EE) is an ophthalmological emergency. We report the long-term outcome of bilateral methicillin-resistant Staphylococcus aureus EE in a 23-year-old healthy immunocompetent athlete who presented with EE secondary to pelvic abscess and remained with excellent vision.

Stability Evaluation of Extemporaneously Compounded Vancomycin Ophthalmic Drops: Effect of Solvents and Storage Conditions

Vancomycin is the drug of choice for methicillin-resistant Staphylococcus aureus keratitis and other ocular infections. Vancomycin ophthalmic drops are not commercially available and require compounding. The present study was designed to investigate the stability of vancomycin ophthalmic drops in normal saline, phosphate-buffered saline (PBS), and balanced salt solution (BSS) while stored at room temperature or under refrigeration. Vancomycin ophthalmic drops (50 mg/mL) were aseptically prepared from commercially available intravenous powder using PBS, BSS, and saline. Solutions were stored at room temperature and in a refrigerator for 28 days. The vancomycin stability was tested by a microbiology assay and high-performance liquid chromatography HPLC analysis immediately after formulation and at days 7, 14, and 28 after storage at room temperature or under refrigeration. The pH, turbidity was also tested. Vancomycin formulations in PBS, BSS and normal saline had initial pH of 5; 5.5; 3 respectively. The formulation in PBS developed turbidity and a slight decrease in pH upon storage. Microbiological assay did not show any change in zone of inhibition with any of the formulation upon storage either at room temperature or under refrigeration. HPLC analysis did not detect any decrease in vancomycin concentration or the accumulation of degraded products in any of the formulations upon storage either at room temperature or under refrigeration. Vancomycin ophthalmic drops prepared using PBS, BSS, and normal saline were stable up to the tested time point of 28 days, irrespective of their storage temperature.

Bloodstream infections in critically ill patients with COVID-19

BACKGROUND

Little is known about the incidence and risk of intensive care unit (ICU)-acquired bloodstream infections (BSI) in critically ill patients with coronavirus disease 2019 (COVID-19).

MATERIALS AND METHODS

This retrospective, single-centre study was conducted in Northern Italy. The primary study objectives were as follows: (a) to assess the incidence rate of ICU-acquired BSI and (b) to assess the cumulative risk of developing ICU-acquired BSI.

RESULTS

Overall, 78 critically ill patients with COVID-19 were included in the study. Forty-five episodes of ICU-acquired BSI were registered in 31 patients, with an incidence rate of 47 episodes (95% confidence interval [CI] 35-63) per 1000 patient-days at risk. The estimated cumulative risk of developing at least one BSI episode was of almost 25% after 15 days at risk and possibly surpassing 50% after 30 days at risk. In multivariable analysis, anti-inflammatory treatment was independently associated with the development of BSI (cause-specific hazard ratio [csHR] 1.07 with 95% CI 0.38-3.04 for tocilizumab, csHR 3.95 with 95% CI 1.20-13.03 for methylprednisolone and csHR 10.69 with 95% CI 2.71-42.17 for methylprednisolone plus tocilizumab, with no anti-inflammatory treatment as the reference group; overall P for the dummy variable = 0.003).

CONCLUSIONS

The incidence rate of BSI was high, and the cumulative risk of developing BSI increased with ICU stay. Further study will clarify if the increased risk of BSI we detected in COVID-19 patients treated with anti-inflammatory drugs is outweighed by the benefits of reducing any possible pro-inflammatory dysregulation induced by SARS-CoV-2.

Focusing the Lens on the CAMERA Concepts: Early Combination β-Lactam and Vancomycin Therapy in Methicillin-Resistant Staphylococcus aureus Bacteremia

Methicillin-resistant Staphylococcus aureus (MRSA) has grown to become a major burden on health care systems. The cumulation of limited therapeutic options and worsened patient outcomes with persistent MRSA bacteremia has driven research in optimizing its initial management. The guidelines published by the Infectious Diseases Society of America currently recommend combination therapy for refractory MRSA bacteremia, but the utility of combining antibiotics from the start of therapy is under investigation. The alternative strategy of early use of β-lactam antibiotics in combination with vancomycin upon initial MRSA bacteremia detection has shown promise. While this concept has gained international attention, providers should give this strategy serious consideration prior to implementation. The objective of this review is to examine retrospective and prospective evidence for early combination with vancomycin and β-lactam antibiotics, as well as explore potential consequences of combination therapy.

Emerging drugs for treating methicillin-resistant Staphylococcus aureus

Introduction: In clinical practice, methicillin-resistant Staphylococcus aureus (MRSA) represents a major threat and has been associated with high rates of inadequate antibiotic treatment and significant increases in morbidity, mortality, and overall healthcare costs. The association between the prescription of an inappropriate or delayed antibiotic and impaired clinical outcomes has been widely described. Areas covered: To address the threat of MRSA, many new therapeutic options with a peculiar activity against MRSA have been recently developed and approved. New agents are characterized by specific issues in terms of spectrum of activity, pharmacokinetics, risk of drug-drug interactions, and toxicity, with potential advantages that should be considered in everyday clinical practice. Expert opinion: The most attractive characteristic of new drugs is represented by the broad spectrum of activity against multidrug-resistant pathogens; moreover, new compounds in most cases are characterized by favorable toxicity profiles compared with old drugs currently used in clinical practice. Some of the new antimicrobials will be also available as oral formulations, with the potential for oral switch, even in infections due to resistant pathogens. In particular conditions/populations (e.g. liver failure, renal disease, pregnancy, diabetic, children, and elderly), novel antibiotics with reduced toxicity could be an important option, including after hospital discharge.

Prosthetic joint infections: clinical management, diagnosis, and treatment

PURPOSE OF REVIEW

Prosthetic joint infections (PJIs) represent one of the most disastrous complications in prosthetic surgery, requiring long hospitalization, prolonged antimicrobial treatment and repeated surgical interventions. No gold standard test to formulate diagnosis exist. A combination of high index of suspicion, physical examination, microbiological and biohumoral investigations is required. Therapeutical approach should be based on a multidisciplinary team. In our center, a two-stage approach is preferred. As regards the choice of the empirical antibiotic backbone, individual risk factors for multiple-drug resistant (MDR) pathogens should be considered. Several studies enhance the possibility to shorten the length of antibiotic couses.

RECENT FINDINGS

Some interesting improvements have been made in the setting of PJIs management. As regards diagnosis, novel biomarkers and nuclear imaging are acquiring more importance. Molecular biology techniques also offer the possibility to formulate rapid microbiological identification. The pattern of PJIs is evolving towards higher rates of MDR causes. During the last decade, a number of new antibiotic molecules with activity against MDRs have been approved. Some of them are also available either in oral formulation or as long-acting compounds, offering the opportunity for early patient's discharge, with expected healthcare costs saving.

SUMMARY

Management of PJIs still represents a major threat for clinicians. Improvements in surgical techniques and antibiotic pipeline promise to revolutionize the approach in next years. Despite data from our experience confirm the efficacy of shorter antibiotic courses and the value of new molecules, randomized clinical trials are lacking. More data are needed in order to modify the routine clinical practice.

Effect of Ceftaroline, Vancomycin, Gentamicin, Macrolides, and Ciprofloxacin against Methicillin-Resistant Staphylococcus aureus Isolates: An In Vitro Study

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infection remains a challenging threat because of limited treatment options. Ceftaroline was identified as having potent anti-MRSA activity. Aim: To evaluate the susceptibility of MRSA to gentamicin, macrolides, ciprofloxacin, vancomycin, and ceftaroline and to perform molecular characterization of different resistance genes as aminoglycoside modifying enzyme genes, ermA and ermC, and vanA and vanB genes. Patients and Methods: One hundred non-duplicate MRSA strains were isolated from different samples of hospitalized patients in Cairo University teaching hospitals from November 2015 to August 2016. Determination of antibiotic susceptibility was done using disk diffusion test and minimum inhibitory concentration followed by detection of resistance genes by multiplex polymerase chain reaction (PCR). Results: Of 100 MRSA isolates, 63 (63%) were resistant to gentamicin, erythromycin, clindamycin, and ciprofloxacin, however, all were sensitive to ceftaroline. Fifteen isolates (15%) were vancomycin intermediate resistant and were sensitive to ceftaroline as well. Conclusion: Ceftaroline was potent against MRSA, which was found to be non-susceptible to vancomycin, ciprofloxacin, erythromycin, clindamycin, and gentamicin and it may represent a successful treatment for MRSA infections.

Off-label use of ceftaroline fosamil: A systematic review

Ceftaroline fosamil is a fifth-generation cephalosporin with anti-methicillin-resistant Staphylococcus aureus (MRSA) activity. It has been approved by the EMA and FDA for the treatment of adults and children with community-acquired bacterial pneumonia (CABP) and acute bacterial skin and skin structure infections (ABSSSI). However, ceftaroline fosamil has a broad spectrum of activity, and a good safety and tolerability profile, so is frequently used off-label. The aim of this systematic review was to summarize the safety and efficacy of off-label use of ceftaroline. The review was conducted according to PRISMA guidelines. MEDLINE, EMBASE and CENTRAL databases (2010-2018) were searched using as the main term ceftaroline fosamil and its synonyms in combination with names of infectious diseases of interest. A total of 21 studies with 1901 patients were included: the most common off-label indications for ceftaroline use were bacteremia (n=595), endocarditis (n=171), osteoarticular infections (n=368), hospital-acquired pneumonia (n=115) and meningitis (n=23). The most common reasons for off-label use were persistent or recurrent infection after standard treatment or non-susceptibility to vancomycin and daptomycin. Clinical success was evaluated in 933 patients, and 724 (77%) of these reached this positive outcome. Incidence of adverse events (AEs) was reported in 11 studies. In 83 (9%) cases there were AEs related to the use of ceftaroline; the most common reported AEs were nausea, vomiting, diarrhea, rash and neutropenia. The review results show that ceftaroline may be used in clinical settings other than those currently approved; however, the use of ceftaroline in these contexts deserves further investigation.

In Vitro Activity Of Ceftaroline And Comparators Against Staphylococcus aureus Isolates: Results From 6 Years Of The ATLAS Program (2012 To 2017)

Background

Ceftaroline is effective against methicillin-resistant Staphylococcus aureus (MRSA), but the resistance patterns still need to be defined. This study aimed to investigate the susceptibility of S. aureus to ceftaroline and comparator antimicrobial agents in patients hospitalized due to infection and to observe the patterns among different regions and over the years.

Methods

The Antimicrobial Testing Leadership And Surveillance (ATLAS) program includes medical centers located in five geographical regions (Europe, Asia-Pacific, South America, Africa-West Asia, and the United States). The isolates were collected from different specimens from patients hospitalized between 2012 and 2017 due to documented complicated skin and soft tissue infection, complicated intra-abdominal infection, complicated urinary tract infection, lower respiratory tract infection, and bloodstream infection.

Results

During the study period, 61,045 isolates were tested, including 35,837 MRSA isolates (58.7%) and 25,208 methicillin-sensitive S. aureus (MSSA) isolates (41.3%). For MRSA, the minimal inhibitory concentration (MIC)₅₀, MIC₉₀, and MIC range of ceftaroline were 0.5, 2, and 0.015–64 μg/mL. The proportion of susceptible MRSA strains was 89.3%. The proportion of resistant MRSA strains was 0.7%. The susceptibility of all S. aureus, MRSA, and MSSA strains to ceftaroline remained relatively constant from 2012 to 2017. The susceptibility to ceftaroline of S. aureus, MRSA, and MSSA strains from the United States, Europe, South America, and Africa/West Asia was high, while the susceptibility of the strains from Asia-Pacific was lower, especially for MRSA.

Conclusion

This study reveals the patterns of ceftaroline susceptibility of MRSA and MSSA around the world and over 6 years.

Important new therapies for methicillin-resistant Staphylococcus aureus

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) infections represent a leading cause of infection-related morbidity and mortality worldwide. There has been a welcome increase in the number of agents available for the treatment of MRSA infection over the last decade and several clinical trials are currently investigating the role of new experimental strategies.Areas covered: The purpose of this manuscript is to review the efficacy and safety of recently approved anti-MRSA molecules as well as some newer agents currently under investigation with a specific focus on the potential role of these drugs in everyday clinical practice.Expert opinion: Many new drugs with an activity against MRSA have been recently approved or are in an advanced stage of development. All these compounds represent promising options to enhance our antibiotic armamentarium. However, data regarding the use of these new compounds in real-life terms are limited and their best placement in therapy and in terms of optimization of medical resources and balance of cost-effectiveness requires further investigation.

Antimicrobial resistance in methicillin-resistant Staphylococcus aureus to newer antimicrobial agents

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) result in significant morbidity and mortality for patients in both community and health care settings. This is primarily due to the difficulty in treating MRSA, which is often resistant to multiple classes of antibiotics. Understanding the mechanisms of antimicrobial resistance (AMR) in MRSA provides insight into the optimal use of antimicrobial agents in clinical practice and also underpins critical aspects of antimicrobial stewardship programs. In this review we delineate the mechanisms, prevalence, and clinical importance of resistance to antibiotics licensed in the past 20 years that target MRSA, as well as new drugs in the pipeline which are likely to be licensed soon. Current gaps in scientific knowledge about MRSA resistance mechanisms are discussed, and topics in the epidemiology of AMR in S. aureus that require further investigation are highlighted.

Possible role of rivoglitazone thiazolidine class of drug as dual-target therapeutic agent for bacterial infections: An in silico study

Infections due to resistant bacteria are the life-threatening and leading cause of mortality worldwide. The current therapy for bacterial infections includes treatment with various drugs and antibiotics. The misuse and over usage of these antibiotics leads to bacterial resistance. There are several mechanisms by which bacteria exhibit resistance to some antibiotics. These include drug inactivation or modification, elimination of antibiotics through efflux pumps, drug target alteration, and modification of metabolic pathway. However, it is difficult to treat infections caused by resistant bacteria by conventional existing therapy. In the present study binding affinities of some glitazones against ParE and MurE bacterial enzymes are investigated by in silico methods. As evident by extra-precision docking and binding free energy calculation (MM-GBSA) results, rivoglitazone exhibited higher binding affinity against both ParE and MurE enzymes compared to all other selected compounds. Further molecular dynamic (MD) simulations were performed to validate the stability of rivoglitazone/4MOT and rivoglitazone/4C13 complexes and to get insight into the binding mode of inhibitor. Thus, we hypothesize that structural modifications of the rivoglitazone scaffold can be useful for the development of an effective antibacterial agent.

New Antibiotics for Pneumonia

Delayed antimicrobial prescriptions and inappropriate treatment can lead to poor outcomes in pneumonia. In nosocomial infections, especially in countries reporting high rates of antimicrobial resistance, the presence of multidrug-resistant gram-negative and gam-positive bacteria can limit options for adequate antimicrobial treatment. New antibiotics, belonging to known classes of antimicrobials or characterized by novel mechanisms of actions, have recently been approved or are under development. Advantages of the new compounds include enhanced spectrum of activity against resistant bacteria, high lung penetration, good tolerability, and possibility for intravenous to oral sequential therapy. This article reviews characteristics of newly approved and investigational compounds.

Antibiotic Resistance and the MRSA Problem

Staphylococcus aureus is capable of becoming resistant to all classes of antibiotics clinically available and resistance can develop through de novo mutations in chromosomal genes or through acquisition of horizontally transferred resistance determinants. This review covers the most important antibiotics available for treatment of S. aureus infections and a special emphasis is dedicated to the current knowledge of the wide variety of resistance mechanisms that S. aureus employ to withstand antibiotics. Since resistance development has been inevitable for all currently available antibiotics, new therapies are continuously under development. Besides development of new small molecules affecting cell viability, alternative approaches including anti-virulence and bacteriophage therapeutics are being investigated and may become important tools to combat staphylococcal infections in the future.

Cerebrospinal fluid pharmacokinetics of ceftaroline in neurosurgical patients with an external ventricular drain

BACKGROUND

Owing to its antibacterial properties, ceftaroline could be attractive for prevention or treatment of bacterial post-neurosurgical meningitis/ventriculitis. However, few data are available concerning its meningeal concentrations.

OBJECTIVES

To investigate ceftaroline CSF pharmacokinetics in ICU patients with an external ventricular drain (EVD).

METHODS

Patients received a single 600 mg dose of ceftaroline as a 1 h intravenous infusion. Blood and CSF samples were collected before and 0.5, 1, 3, 6, 12 and 24 h after the end of the infusion. Concentrations were assayed in plasma and CSF by LC-MS/MS. A two-step compartmental pharmacokinetic analysis was conducted. Ceftaroline plasma data were first analysed, and thereafter plasma parameters estimated and corrected for protein binding of 20% were fixed to fit unbound CSF concentrations. In the final model, parameters for both plasma and CSF data were simultaneously estimated.

RESULTS

Nine patients with an EVD were included. The Cmax was 18.29 ± 3.33 mg/L in plasma (total concentrations) and at 0.22 ± 0.17 mg/L in CSF (unbound concentration). The model-estimated CSF input/CSF output clearance ratio was 9.4%, attesting to extensive efflux transport at the blood-CSF barrier.

CONCLUSIONS

Ceftaroline CSF concentrations are too low to ensure prophylactic protection against most pathogens with MICs between 1 and 2 mg/L, owing to its limited central distribution.

tert-Butylphenylthiazoles with an oxadiazole linker: a novel orally bioavailable class of antibiotics exhibiting antibiofilm activity

The structure–activity and structure–kinetic relationships of a new tert-butylphenylthiazole series with oxadiazole linkers were conducted with the objective of obtaining a new orally available antibacterial compounds. Twenty-two new compounds were prepared, purified and identified. Their activity against methicillin-resistant Staphylococcus aureus were examined. Compound 20 with 3-hydroxyazetidine as a nitrogenous side chain showed promising activity against twenty-four clinical isolates, including vancomycin-resistant staphylococcal and enterococcal species with MIC values ranging from 4–8 μg mL⁻¹. Additional advantages of this compound include an ability to eradicate staphylococcal biofilm mass in a dose-dependent manner as well as high metabolic stability after an oral dose of 25 mg kg⁻¹ with a biological half-life that exceeds 5 hours and a plasma concentration (C_max) that exceeds the MIC values.

The structure–activity and structure–kinetic relationships of a new tert-butylphenylthiazole series with oxadiazole linkers were conducted with the objective of obtaining a new orally available antibacterial compounds.

Streptomyces as a Prominent Resource of Future Anti-MRSA Drugs

Methicillin-resistant Staphylococcus aureus (MRSA) pose a significant health threat as they tend to cause severe infections in vulnerable populations and are difficult to treat due to a limited range of effective antibiotics and also their ability to form biofilm. These organisms were once limited to hospital acquired infections but are now widely present in the community and even in animals. Furthermore, these organisms are constantly evolving to develop resistance to more antibiotics. This results in a need for new clinically useful antibiotics and one potential source are the Streptomyces which have already been the source of several anti-MRSA drugs including vancomycin. There remain large numbers of Streptomyces potentially undiscovered in underexplored regions such as mangrove, deserts, marine, and freshwater environments as well as endophytes. Organisms from these regions also face significant challenges to survival which often result in the production of novel bioactive compounds, several of which have already shown promise in drug development. We review the various mechanisms of antibiotic resistance in MRSA and all the known compounds isolated from Streptomyces with anti-MRSA activity with a focus on those from underexplored regions. The isolation of the full array of compounds Streptomyces are potentially capable of producing in the laboratory has proven a challenge, we also review techniques that have been used to overcome this obstacle including genetic cluster analysis. Additionally, we review the in vivo work done thus far with promising compounds of Streptomyces origin as well as the animal models that could be used for this work.

Peritoneal dialysis-related peritonitis: challenges and solutions

Peritoneal dialysis is an effective treatment modality for patients with end-stage renal disease. The relative use of peritoneal dialysis versus hemodialysis varies widely by country. Data from a 2004 survey reports the percentage of patients with end-stage renal disease treated with peritoneal dialysis to be 5%-10% in economically developed regions like the US and Western Europe to as much as 75% in Mexico. This disparity is probably related to the availability and access to hemodialysis, or in some cases patient preference for peritoneal over hemodialysis. Peritoneal dialysis-related peritonitis remains the major complication and primary challenge to the long-term success of peritoneal dialysis. Fifty years ago, with the advent of the Tenckhoff catheter, patients averaged six episodes of peritonitis per year on peritoneal dialysis. In 2016, the International Society for Peritoneal Dialysis proposed a benchmark of 0.5 episodes of peritonitis per year or one episode every 2 years. Despite the marked reduction in peritonitis over time, peritonitis for the individual patient is problematic. The mortality for an episode of peritonitis is 5% and is a cofactor for mortality in another 16% of affected patients. Prevention of peritonitis and prompt and appropriate management of peritonitis is essential for the long-term success of peritoneal dialysis in all patients. In this review, challenges and solutions are addressed regarding the pathogenesis, clinical features, diagnosis, treatment, and prevention of peritoneal dialysis-related peritonitis from the viewpoint of an infectious disease physician.

DISC: Describing Infections of the Spine treated with Ceftaroline

OBJECTIVES

Infections of the spine lead to considerable morbidity and a high cost to the global healthcare system. Currently, evidence for using ceftaroline, an advanced-generation cephalosporin active against methicillin-resistant Staphylococcus aureus (MRSA), in spine infections is limited.

METHODS

Describing Infections of the Spine treated with Ceftaroline (DISC) is a multicentre, retrospective, cohort study that evaluated ceftaroline for treating spine infections. Patients were included if they were aged ≥18 years, diagnosed with a spine infection and treated with ceftaroline for ≥28 days. A control group was identified with the same inclusion criteria as the study population except they were treated with a comparator antibiotic for ≥28 days.

RESULTS

Thirty-seven patients were included each in the ceftaroline and control groups. MRSA was the most commonly identified pathogen. With no differences between groups in age, sex, race or co-morbidities (with the exception of chronic kidney disease), treatment with ceftaroline led to similar clinical success compared with the control group. Multivariate regression analysis did not show a significant difference between the two groups in terms of clinical success after controlling for other covariates (adjusted odds ratio=1.49; P=0.711). More patients who received ceftaroline were discharged to an extended-care or rehabilitation facility than home compared with controls (81% vs. 54%, respectively; P=0.024). Side effects and toxicities were rare, including one case of eosinophilic pneumonia in the ceftaroline group.

CONCLUSIONS

Ceftaroline appears to be a safe and effective therapy for infections of the spine, including from MRSA.

Ceftaroline fosamil laden allograft: A new modality in reducing infection?

PURPOSE

Allograft infection remains the greatest challenge in orthopaedic reconstructive surgery especially methicillin-resistant Staphylococcus aureus (MRSA). This risk can be minimized with the use of antibiotic laden allograft (ALA) via iontophoresis. Ceftaroline fosamil (CF) is an advanced-generation cephalosporin, an alternative treatment for MRSA infections. Its antibacterial activity and safety profile are better than vancomycin. CF iontophoresed bone has not been used before. This study was conducted to establish the feasibility of creating a CF ALA and establish the prime conditions for its expenditure.

METHOD

We created an iontophoresis cell; 3% CF was inserted within medullary segment of goat bone and sealed from external saline solution. The cell operated at the following voltages 30, 60 and 90 V and at the following durations 5, 10, 15, 20, 25 and 30 min. Information regarding optimal conditions for its application was then obtained. After which, correlation between voltages and time with CF concentration in the bone was analysed. A bioavailability test was also conducted to observe the optimal rate of CF elution from the graft.

RESULT

The optimal condition for the impregnation process is 3% CF at 90 V for 10 min. Bone graft impregnated with CF at optimal conditions can elute above minimum inhibitory concentration of the CF against MRSA for 21 days.

CONCLUSION

CF iontophoresis was found feasible for allograft impregnation. The technique is simple, inexpensive and reproducible clinically. Iontophoresis offers a novel solution to reduce the rate of perioperative infection in reconstructive surgery involving use of bone graft.

Mechanisms of antimicrobial resistance among hospital-associated pathogens

INTRODUCTION

The introduction of antibiotics revolutionized medicine in the 20th-century permitting the treatment of once incurable infections. Widespread use of antibiotics, however, has led to the development of resistant organisms, particularly in the healthcare setting. Today, the clinician is often faced with pathogens carrying a cadre of resistance determinants that severely limit therapeutic options. The genetic plasticity of microbes allows them to adapt to stressors via genetic mutations, acquisition or sharing of genetic material and modulation of genetic expression leading to resistance to virtually any antimicrobial used in clinical practice. Areas covered: This is a comprehensive review that outlines major mechanisms of resistance in the most common hospital-associated pathogens including bacteria and fungi. Expert commentary: Understanding the genetic and biochemical mechanisms of such antimicrobial adaptation is crucial to tackling the rapid spread of resistance, can expose unconventional therapeutic targets to combat multidrug resistant pathogens and lead to more accurate prediction of antimicrobial susceptibility using rapid molecular diagnostics. Clinicians making treatment decisions based on the molecular basis of resistance may design therapeutic strategies that include de-escalation of broad spectrum antimicrobial usage, more focused therapies or combination therapies. These strategies are likely to improve patient outcomes and decrease the risk of resistance in hospital settings.

Antibiotic resistance in Staphylococcus aureus. Current status and future prospects

The major targets for antibiotics in staphylococci are (i) the cell envelope, (ii) the ribosome and (iii) nucleic acids. Several novel targets emerged from recent targeted drug discovery programmes including the ClpP protease and FtsZ from the cell division machinery. Resistance can either develop by horizontal transfer of resistance determinants encoded by mobile genetic elements viz plasmids, transposons and the staphylococcal cassette chromosome or by mutations in chromosomal genes. Horizontally acquired resistance can occur by one of the following mechanisms: (i) enzymatic drug modification and inactivation, (ii) enzymatic modification of the drug binding site, (iii) drug efflux, (iv) bypass mechanisms involving acquisition of a novel drug-resistant target, (v) displacement of the drug to protect the target. Acquisition of resistance by mutation can result from (i) alteration of the drug target that prevents the inhibitor from binding, (ii) derepression of chromosomally encoded multidrug resistance efflux pumps and (iii) multiple stepwise mutations that alter the structure and composition of the cell wall and/or membrane to reduce drug access to its target. This review focuses on development of resistance to currently used antibiotics and examines future prospects for new antibiotics and informed use of drug combinations.

Virulence Factor Targeting of the Bacterial Pathogen Staphylococcus aureus for Vaccine and Therapeutics

BACKGROUND

Staphylococcus aureus is a major bacterial pathogen capable of causing a range of infections in humans from gastrointestinal disease, skin and soft tissue infections, to severe outcomes such as sepsis. Staphylococcal infections in humans can be frequent and recurring, with treatments becoming less effective due to the growing persistence of antibiotic resistant S. aureus strains. Due to the prevalence of antibiotic resistance, and the current limitations on antibiotic development, an active and highly promising avenue of research has been to develop strategies to specifically inhibit the activity of virulence factors produced S. aureus as an alternative means to treat disease.

OBJECTIVE

In this review we specifically highlight several major virulence factors produced by S. aureus for which recent advances in antivirulence approaches may hold promise as an alternative means to treating diseases caused by this pathogen. Strategies to inhibit virulence factors can range from small molecule inhibitors, to antibodies, to mutant and toxoid forms of the virulence proteins.

CONCLUSION

The major prevalence of antibiotic resistant strains of S. aureus combined with the lack of new antibiotic discoveries highlight the need for vigorous research into alternative strategies to combat diseases caused by this highly successful pathogen. Current efforts to develop specific antivirulence strategies, vaccine approaches, and alternative therapies for treating severe disease caused by S. aureus have the potential to stem the tide against the limitations that we face in the post-antibiotic era.

Efficacy of Ceftaroline against Methicillin-Susceptible Staphylococcus aureus Exhibiting the Cefazolin High-Inoculum Effect in a Rat Model of Endocarditis

Certain Staphylococcus aureus strains exhibit an inoculum effect (InE) with cefazolin (CFZ) that has been associated with therapeutic failures in high-inoculum infections. We assessed the in vitro activities of ceftaroline (CPT), CFZ, and nafcillin (NAF) against 17 type A β-lactamase (βla)-producing, methicillin-susceptible S. aureus (MSSA) strains, including the previously reported TX0117, which exhibits the CFZ InE, and its βla-cured derivative, TX0117c. Additionally, we determined the pharmacokinetics of CPT in rats after single intramuscular doses of 20 and 40 mg/kg of body weight and evaluated the activities of CPT (40 mg/kg every 8 h [q8h]), CFZ, and NAF against TX0117 and TX0117c in a rat model of infective endocarditis. No InE was observed for CPT or NAF, whereas a marked InE was detected for CFZ (MIC, 8 to ≥128 μg/ml). CPT and NAF treatment against TX0117 resulted in mean bacterial counts of 2.3 and 2.1 log10 CFU/g in vegetations, respectively, compared to a mean of 5.9 log10 CFU/g in the CFZ-treated group (CPT and NAF versus CFZ, P = 0.001; CPT versus NAF, P = 0.9830). Both CFZ and CPT were efficacious against the βla-cured derivative, TX0117c, compared to time zero (t0) (P = <0.0001 and 0.0015, respectively). Our data reiterate the in vivo consequences of the CFZ InE and show that CPT is not affected by this phenomenon. CPT might be considered for high-inoculum infections caused by MSSA exhibiting the CFZ InE.

New strategies for targeting and treatment of multi-drug resistant Staphylococcus aureus

Staphylococcus aureus is a major cause of bacterial infection in humans, and has been notoriously able to acquire resistance to a variety of antibiotics. An example is methicillin-resistant S. aureus (MRSA), which despite having been initially associated with clinical settings, now is one of the key causative agents of community-acquired infections. Antibiotic resistance in S. aureus involves mechanisms ranging from drug efflux to increased expression or mutation of target proteins, and this has required innovative approaches to develop novel treatment methodologies. This review provides an overview of the major mechanisms of antibiotic resistance developed by S. aureus, and describes the emerging alternatives being sought to circumvent infection and proliferation, including new generations of classic antibiotics, synergistic approaches, antibodies, and targeting of virulence factors.

Ceftaroline fosamil monotherapy for methicillin-resistant Staphylococcus aureus bacteremia: a comparative clinical outcomes study

OBJECTIVES

Vancomycin is the treatment of choice for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia; however, its use has been subject to scrutiny due to failure in severe infections. Ceftaroline fosamil (CPT-F) is approved for MRSA acute bacterial skin and skin structure infections, but not for bloodstream infections. The clinical outcomes of treatment with CPT-F in patients with MRSA bacteremia were evaluated.

METHODS

Patients diagnosed with MRSA bacteremia at Henry Ford Hospital in Detroit, Michigan, USA, involving isolates with a vancomycin minimum inhibitory concentration ≥1.0mg/l and susceptible in vitro to CPT-F, were systematically reviewed retrospectively. Ceftaroline fosamil-treated patients were matched with at least two vancomycin- and/or one daptomycin-treated control patient based on age-patients age 65 years or greater or less than 65 years of age. Outcomes evaluated included the duration of hospitalization, duration of therapy, adverse events, relapse, hospital readmission, and death.

RESULTS

Thirty consecutive cases of MRSA bacteremia treated with CPT-F during the period May 2011 to June 2013 were identified; these patients were matched to 56 MRSA bacteremia patients treated with vancomycin and 46 MRSA bacteremia patients treated with daptomycin. The primary source of MRSA bacteremia in the cohort treated with CPT-F was endocarditis (n=7, 23%), skin/wound (n=9, 30%), and bone/joint (n=8, 27%). The MRSA bacteremia in those treated with CPT-F was community-acquired in 43% of cases, healthcare-associated in 43%, and hospital-acquired in 13%. The mean length of hospital stay for these patients was 22 days. The overall 30-day mortality rate was 13% (n=4) in CPT-F patients versus 24% (n=11) in daptomycin patients and 11% (n=6) in vancomycin patients (p=0.188).

CONCLUSIONS

CPT-F demonstrated comparable clinical outcomes in MRSA bacteremia patients compared with the other agents, especially as salvage therapy.

Pharmacodynamics of Ceftaroline plus Ampicillin against Enterococcus faecalis in an In Vitro Pharmacokinetic/Pharmacodynamic Model of Simulated Endocardial Vegetations

The combination of ampicillin plus ceftaroline has been suggested to be more reliably synergistic against Enterococcus faecalis than ampicillin plus ceftriaxone using time-kill methods. The purpose of this study was to determine if this trend persists in a two-compartment model of simulated endocardial vegetations (SEV) using clinically relevant pharmacokinetic exposures of these antimicrobials. Three clinically derived E. faecalis strains were included in the study. The MICs of study antimicrobials were determined by broth microdilution. Simulations of ampicillin (2 g every 4 h [q4h]; maximum concentration of drug in serum [Cmax], 72.4 mg/liter; half-life [t1/2], 1.9 h), ceftaroline-fosamil (600 mg q8h; Cmax, 21.3 mg/liter; t1/2, 2.66 h), ceftriaxone (Cmax, 257 mg/liter; t1/2, 8 h), and ampicillin plus ceftaroline and ampicillin plus ceftriaxone were evaluated against 3 strains of E. faecalis isolated from patients with endocarditis in an in vitro PK/PD SEV model over 72 h, with a starting inoculum of ∼9 log10 CFU/g. All strains were susceptible to ampicillin (MIC, ≤2 mg/liter). Ceftaroline MICs varied from 2 to 16 mg/liter. All strains had ceftriaxone MICs of 256 mg/liter. W04 and W151 exhibited high-level aminoglycoside resistance but W07 did not. Ampicillin plus ceftaroline resulted in significantly greater reductions in CFU per gram by 72 h than ampicillin for all strains (P ≤ 0.025) than ampicillin plus ceftriaxone for W04 (P = 0.019) but not W07 or W151 (P ≥ 0.15). A 4-fold increase in ampicillin MIC was observed for W07 at 72 h, but this was prevented by the addition of ceftaroline or ceftriaxone. The combination of ampicillin plus ceftaroline appears to be at least as efficacious as ampicillin plus ceftriaxone and may lead to improved activity against some strains of E. faecalis, but these differences may be small and the clinical significance should not be overestimated.

The most appropriate therapeutic strategy for acute lower respiratory tract infections: a Delphi-based approach

Lower respiratory tract infections (LRTIs) cause high morbidity and mortality worldwide. Empiric therapy often base the choice of antibiotic treatment on antibacterial spectrum of the agent rather than on its pharmacological properties or the pathogen resistance profile. Inappropriate prescribing leads to therapeutic failure and antibiotic resistance, with increasing direct and indirect health costs. A consensus on appropriate prescribing in LRTI therapy was appraised by this Delphi exercise, based on a panel of 70 pulmonologists, coordinated by a Scientific Committee of nine experts in respiratory medical care. Full or very high consensus was reached on several issues, including the role of oral cephalosporins in first-line treatments of LRTIs and the appropriateness of cefditoren, with balanced spectrum and high intrinsic activity, in LRTI treatment. Evidence-based medicine approach and a comprehensive process of disease management, from diagnosis to therapy and follow-up, should guide antibiotic prescribing.

Treatment of Staphylococcus aureus Infections

Staphylococcus aureus, although generally identified as a commensal, is also a common cause of human bacterial infections, including of the skin and other soft tissues, bones, bloodstream, and respiratory tract. The history of S. aureus treatment is marked by the development of resistance to each new class of antistaphylococcal antimicrobial drugs, including the penicillins, sulfonamides, tetracyclines, glycopeptides, and others, complicating therapy. S. aureus isolates identified in the 1960s were sometimes resistant to methicillin, a ß-lactam antimicrobial active initially against a majority S. aureus strains. These MRSA isolates, resistant to nearly all ß-lactam antimicrobials, were first largely confined to the health care environment and the patients who attended it. However, in the mid-1990s, new strains, known as community-associated (CA-) MRSA strains, emerged. CA-MRSA organisms, compared with health care-associated (HA-) MRSA strain types, are more often susceptible to multiple classes of non ß-lactam antimicrobials. While infections caused by methicillin-susceptible S. aureus (MSSA) strains are usually treated with drugs in the ß-lactam class, such as cephalosporins, oxacillin or nafcillin, MRSA infections are treated with drugs in other antimicrobial classes. The glycopeptide drug vancomycin, and in some countries teicoplanin, is the most common drug used to treat severe MRSA infections. There are now other classes of antimicrobials available to treat staphylococcal infections, including several that have been approved after 2009. The antimicrobial management of invasive and noninvasive S. aureus infections in the ambulatory and in-patient settings is the topic of this review. Also discussed are common adverse effects of antistaphylococcal antimicrobial agents, advantages of one agent over another for specific clinical syndromes, and the use of adjunctive therapies such as surgery and intravenous immunoglobulin. We have detailed considerations in the therapy of noninvasive and invasive S. aureus infections. This is followed by sections on specific clinical infectious syndromes including skin and soft tissue infections, bacteremia, endocarditis and intravascular infections, pneumonia, osteomyelitis and vertebral discitis, epidural abscess, septic arthritis, pyomyositis, mastitis, necrotizing fasciitis, orbital infections, endophthalmitis, parotitis, staphylococcal toxinoses, urogenital infections, and central nervous system infections.

New therapeutic options for respiratory tract infections

PURPOSE OF REVIEW

The progressive increase of respiratory tract infections caused by multidrug-resistant organisms (MDROs) has been associated with delays in the prescription of an adequate antibiotic treatment and increased mortality, representing a major concern in both community and hospital settings. When infections because of methicillin-resistant Staphylococcus aureus (MRSA) are suspected, vancomycin still represents the first choice, although its efficacy has been recently questioned in favor of new drugs, reported to provide better clinical outcomes. Moreover, few therapeutic options are currently available for the treatment of severe infections caused by Multidrug-resistant (MDR) Gram-negative pathogens, which are frequently resistant to all the available β-lactams, including carbapenems. We have reviewed the therapeutic options for the treatment of respiratory tract infections that have recently become available with promising implications for clinical practice, including ceftaroline, ceftrobiprole, tedizolid, telavancin, delafloxacin, eravacycline, and new β-lactams/β-lactamase inhibitors.

RECENT FINDINGS

A number of new antimicrobials with activity against MDROs have been recently approved for the treatment of respiratory tract infections, and other agents are under investigation. Recent developments, with a specific focus on the possible advantages of new drugs for the management of respiratory tract infections caused by MDROs in everyday clinical practice are discussed.

SUMMARY

Newly approved and investigational drugs for the treatment of respiratory tract infections are expected to offer many advantages for the management of patients with suspected or confirmed infections caused by MDROs. Most promising features among new compounds include the broad spectrum of activity against both MRSA and MDR Gram-negative bacteria, a limited risk of antimicrobial resistance, the availability of oral formulations, and a promising safety profile.

New therapeutic options for skin and soft tissue infections

PURPOSE OF REVIEW

The occurrence of methicillin-resistance in Staphylococcus aureus, that represents the most frequent cause of complicated skin and soft tissue infections (cSSTIs) worldwide, is a major concern and has been associated with increased length of stay, health care costs, and overall mortality. Although vancomycin is still considered the standard therapy in this setting, limitations of its use in clinical practice are represented by a progressive increase in methicillin-resistant S. aureus (MRSA) minimum inhibitory concentrations, drug-related toxicity, and the lack of an oral formulation. New therapeutic options for MRSA cSSTIs have recently become available, with promising implications for the management of cSSTIs in clinical practice.

RECENT FINDINGS

A number of new antimicrobials with activity against MRSA have been recently approved for the treatment of cSSTIs, and other agents are under investigation. We have reviewed the recent developments, with a specific focus on the possible advantages of new drugs for the management of cSSTIs into the everyday clinical practice.

SUMMARY

The new approved drugs for the treatment of cSSTIs are expected to offer many advantages for the management of patients with suspected or confirmed MRSA cSSTIs. The most promising features of the new compounds include the availability of oral formulations, once-weekly intravenous regimens, and broad spectra of activity.

Evolution of Ceftaroline-Resistant Mrsa in a Child with Cystic Fibrosis Following Repeated Antibiotic Exposure

Ceftaroline is the first β-lactam antibiotic with activity against methicillin-resistant Staphylococcus aureus (MRSA). We describe a ceftaroline-resistant MRSA strain, isolated from a girl with cystic fibrosis after 22 ceftaroline treatment courses. MRSA genome sequencing documented a Tyr446Asn alteration in penicillin binding protein 2 that appeared responsible for resistance. Noncompartmental ceftaroline pharmacokinetic evaluation in our patient documented increased clearance and volume of distribution compared with adults.

One ring to rule them all: Current trends in combating bacterial resistance to the β-lactams

From humble beginnings of a contaminated petri dish, β-lactam antibiotics have distinguished themselves among some of the most powerful drugs in human history. The devastating effects of antibiotic resistance have nevertheless led to an "arms race" with disquieting prospects. The emergence of multidrug resistant bacteria threatens an ever-dwindling antibiotic arsenal, calling for new discovery, rediscovery, and innovation in β-lactam research. Here the current state of β-lactam antibiotics from a structural perspective was reviewed.

Effects of Subinhibitory Concentrations of Ceftaroline on Methicillin-Resistant Staphylococcus aureus (MRSA) Biofilms

Ceftaroline (CPT) is a novel cephalosporin with in vitro activity against Staphylococcus aureus. Ceftaroline exhibits a level of binding affinity for PBPs in S. aureus including PBP2a of methicillin-resistant S. aureus (MRSA). The aims of this study were to investigate the morphological, physiological and molecular responses of MRSA clinical strains and MRSA biofilms to sub-MICs (1/4 and 1/16 MIC) of ceftaroline by using transmission, scanning and confocal microscopy. We have also used quantitative Real-Time PCR to study the effect of sub-MICs of ceftaroline on the expression of the staphylococcal icaA, agrA, sarA and sasF genes in MRSA biofilms. In one set of experiments, ceftaroline was able to inhibit biofilm formation in all strains tested at MIC, however, a strain dependent behavior in presence of sub-MICs of ceftaroline was shown. In a second set of experiments, destruction of preformed biofilms by addition of ceftaroline was evaluated. Ceftaroline was able to inhibit biofilm formation at MIC in all strains tested but not at the sub-MICs. Destruction of preformed biofilms was strain dependent because the biofilm formed by a matrix-producing strain was resistant to a challenge with ceftaroline at MIC, whereas in other strains the biofilm was sensitive. At sub-MICs, the impact of ceftaroline on expression of virulence genes was strain-dependent at 1/4 MIC and no correlation between ceftaroline-enhanced biofilm formation and gene regulation was established at 1/16 MIC. Our findings suggest that sub-MICs of ceftaroline enhance bacterial attachment and biofilm formation by some, but not all, MRSA strains and, therefore, stress the importance of maintaining effective bactericidal concentrations of ceftaroline to fight biofilm-MRSA related infections.

Treatment of Methicillin-Resistant Staphylococcus aureus Bacteremia

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of health care-associated infections. Vancomycin remains an acceptable treatment option. There has been a welcome increase in the number of agents available for the treatment of MRSA infection. These drugs have certain differentiating attributes and may offer some advantages over vancomycin, but they also have significant limitations. These agents provide some alternative when no other options are available.

Current therapeutics and prophylactic approaches to treat pneumonia

Bacterial pneumonia caused by Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Mycoplasma pneumoniae, and Klebsiella pneumoniae represents a frequent cause of mortality worldwide. The increased incidence of pneumococcal diseases in both developed and developing countries is alarmingly high, affecting infants and aged adult populations. The growing rate of antibiotic resistance and biofilm formation on medical device surfaces poses a greater challenge for treating respiratory infections. Over recent years, a better understanding of bacterial growth, metabolism, and virulence has offered several potential targets for developing therapeutics against bacterial pneumonia. This chapter will discuss the current and developing trends in treating bacterial pneumonia.

Evaluation of Ceftaroline Alone and in Combination against Biofilm-Producing Methicillin-Resistant Staphylococcus aureus with Reduced Susceptibility to Daptomycin and Vancomycin in an In Vitro Pharmacokinetic/Pharmacodynamic Model

Annually, medical device infections are associated with >250,000 catheter-associated bloodstream infections (CLABSI), with up to 25% mortality. Staphylococcus aureus, a primary pathogen in these infections, is capable of biofilm production, allowing organism persistence in harsh environments, offering antimicrobial protection. With increases in S. aureus isolates with reduced susceptibility to current agents, ceftaroline (CPT) offers a therapeutic alternative. Therefore, we evaluated whether CPT would have a role against biofilm-producing methicillin-resistant S. aureus (MRSA), including those with decreased susceptibilities to alternative agents. In this study, we investigated CPT activity alone or combined with daptomycin (DAP) or rifampin (RIF) against 3 clinical biofilm-producing MRSA strains in an in vitro biofilm pharmacokinetic/pharmacodynamic (PK/PD) model. Simulated antimicrobial regimens were as follows: 600 mg of CPT every 8 h (q8h) (free maximum concentration of drug [fCmax], 17.04 mg/liter; elimination half-life [t1/2], 2.66 h), 12 mg/kg of body weight/day of DAP (fCmax, 14.7 mg/liter; t1/2, 8 h), and 450 mg of RIF q12h (fCmax, 3.5 mg/liter; t1/2, 3.4 h), CPT plus DAP, and CPT plus RIF. Samples were obtained and plated to determine colony counts. Differences in log10 CFU/cm(2) were evaluated by analysis of variance with Tukey's post hoc test. The strains were CPT and vancomycin susceptible and DAP nonsusceptible (DNS). CPT displayed activity throughout the experiment. DAP demonstrated initial activity with regrowth at 24 h in all strains. RIF was comparable to the drug-free control, and little benefit was observed when combined with CPT. CPT plus DAP displayed potent activity, with an average log10 CFU/cm(2) reduction of 3.33 ± 1.01 from baseline. CPT demonstrated activity against biofilm-producing DNS MRSA. CPT plus DAP displayed therapeutic enhancement over monotherapy, providing a potential option for difficult-to-treat medical device infections.

New antibiotics against gram-positives: present and future indications

Gram-positive cocci are the most frequent aetiology of community and nosocomially bacterial acquired infections. The prevalence of multidrug-resistant gram-positive bacteria is increasing and is associated with high morbidity and mortality. New antibiotics will be available in the European market during the next months. This revision is focused on lipoglycopeptides, new cephalosporins active against methicillin-resistant Staphylococcus aureus (MRSA) and the new oxazolidinone, tedizolid. The purpose of this review is to describe their in vitro activity, pharmacokinetic and pharmacodynamic characteristics, and experience from clinical trials.