Novel pharmacotherapy for the treatment of hospital-acquired and ventilator-associated pneumonia caused by resistant gram-negative bacteria

In vivo pharmacokinetic/pharmacodynamic evaluation of cefepime/taniborbactam combination against cefepime-non-susceptible Enterobacterales and Pseudomonas aeruginosa in a murine pneumonia model

BACKGROUND

Cefepime/taniborbactam is a cephalosporin/bicyclic boronate β-lactamase inhibitor combination in clinical development for nosocomial pneumonia due to MDR Gram-negative bacteria. A murine pneumonia model was used to characterize cefepime/taniborbactam in vivo pharmacodynamics against Enterobacterales and Pseudomonas aeruginosa strains.

METHODS

Clinical cefepime-non-susceptible Enterobacterales and P. aeruginosa strains expressing serine carbapenemases and/or other cefepime-hydrolysing β-lactamases with cefepime/taniborbactam combination MICs of 0.12-16 mg/L were used. Cefepime and taniborbactam human-simulated regimens equivalent to clinical doses (i.e. 2/0.5 g q8h) were established in the pneumonia model. The in vivo activity of the cefepime human-simulated regimen given alone or concomitantly with escalating taniborbactam exposures against eight Enterobacterales and four P. aeruginosa strains was assessed. Taniborbactam pharmacokinetics were evaluated to determine systemic exposures of regimens used; taniborbactam fAUC0-24/MIC values required for efficacy were estimated using the Hill equation. In addition, the in vivo activity of the cefepime/taniborbactam combination human-simulated regimen was assessed against 18 strains.

RESULTS

Among Enterobacterales, median taniborbactam fAUC0-24/MIC values associated with stasis and 1 log kill were 0.96 and 4.03, respectively, while for P. aeruginosa, requirements were 1.35 and 3.02 for stasis and 1 log kill, respectively. The cefepime/taniborbactam human-simulated regimen produced >2 log kill in 14/18 strains and >1 log kill in 18/18 strains.

CONCLUSIONS

Cefepime/taniborbactam produced marked in vivo bactericidal activity against cefepime-non-susceptible Enterobacterales and P. aeruginosa isolates with cefepime/taniborbactam MICs up to and including 16 mg/L in the pneumonia model. Assessments of the probability of clinical attainment of the identified targets should be undertaken to support the selected cefepime/taniborbactam dose for treatment of nosocomial pneumonia.

Bronchopulmonary disposition of IV cefepime/taniborbactam (2-0.5 g) administered over 2 h in healthy adult subjects

INTRODUCTION

Taniborbactam (formerly VNRX-5133) is an investigational β-lactamase inhibitor in clinical development in combination with cefepime for the treatment of MDR Gram-negative pathogens.

OBJECTIVES

To assess the safety profile and pulmonary disposition of 2-0.5 g cefepime/taniborbactam administered as a 2 h IV infusion every 8 h following three doses in healthy adult subjects.

METHODS

In this Phase 1 trial, open-label study, plasma samples were collected over the last dosing interval, and subjects (n = 20) were randomized to undergo bronchoalveolar lavage (BAL) at four timepoints after the last dose. Drug concentrations in plasma (total and free as determined by protein binding), BAL fluid and alveolar macrophages (AM) were determined by LC-MS/MS, and the urea correction method was used to calculate epithelial lining fluid (ELF) drug concentrations. Pharmacokinetic parameters were estimated by non-compartmental analysis.

RESULTS

Mean (±SD) taniborbactam Cmax and AUC0-8 in plasma were 24.1 ± 4.1 mg/L and 81.9 ± 13.9 mg·h/L, respectively. Corresponding values for cefepime were 118.4 ± 29.7 mg/L and 346.7 ± 71.3 mg·h/L. Protein binding was 0% for taniborbactam and 22.4% for cefepime. Mean taniborbactam concentrations (mg/L) at 2, 4, 6 and 8 h were 3.9, 1.9, 1.0 and 0.3 in ELF and 12.4, 11.5, 14.3 and 14.9 in AM, with corresponding AUC0-8 ELF of 13.8 and AUC0-8 AM of 106.0 mg·h/L. Cefepime AUC0-8 ELF was 77.9 mg·h/L. No serious adverse events were observed.

CONCLUSION

The observed bronchopulmonary exposures of taniborbactam and cefepime can be employed to design optimal dosing regimens for clinical trials in patients with pneumonia.

Pharmacokinetic/Pharmacodynamic Analysis of Continuous-Infusion Fosfomycin in Combination with Extended-Infusion Cefiderocol or Continuous-Infusion Ceftazidime-Avibactam in a Case Series of Difficult-to-Treat Resistant Pseudomonas aeruginosa Bloodstream Infections and/or Hospital-Acquired Pneumonia

Objectives: To perform a pharmacokinetic/pharmacodynamic (PK/PD) analysis of continuous-infusion (CI) fosfomycin combined with extended-infusion (EI) cefiderocol or CI ceftazidime-avibactam in a case series of severe difficult-to-treat Pseudomonas aeruginosa (DTR-PA) infections. Methods: A single-center retrospective study of patients who were treated with CI fosfomycin plus EI cefiderocol or CI ceftazidime-avibactam for severe DTR-PA infections and who underwent therapeutic drug monitoring (TDM), from 1 September 2021 to 30 June 2022 was performed. Concentrations were measured at steady-state (Css) for CI fosfomycin and ceftazidime-avibactam and at trough (Cmin) for EI cefiderocol. Joint PK/PD targets of combination therapy were analyzed (thresholds: area-under-the curve to minimum inhibitory concentration (AUC/MIC) ratio > 40.8 for fosfomycin; ceftazidime Css/MIC ratio ≥ 4 coupled with avibactam Css > 4 mg/L for ceftazidime-avibactam; Cmin/MIC ratio ≥ 4 for cefiderocol). Joint PK/PD targets of the combination therapy were analyzed and defined as optimal when both were achieved, quasi-optimal if only one of the two was achieved, and suboptimal if none of the two was achieved). The relationship between joint PK/PD target attainment and microbiological response was assessed. Results: Six patients (three pneumonia, two BSI + pneumonia, and one BSI) were included. The joint PK/PD targets were optimal in four cases and quasi-optimal in the other two. Microbiological eradication (ME) occurred in 4/4 of patients with optimal joint PK/PD targets and in one of the two patients with quasi-optimal joint PK/PD targets. Conclusions: Attaining optimal joint PK/PD targets with a combo-therapy of CI fosfomycin plus EI cefiderocol or CI ceftazidime-avibactam could represent an effective strategy for granting favorable microbiological outcomes in patients with DTR-PA pneumonia and/or BSI.

A Systematic Review of Antibiotic Resistance Trends and Treatment Options for Hospital-Acquired Multidrug-Resistant Infections

Antimicrobial resistance is a major public health challenge described by the World Health Organization as one of the top 10 public health challenges worldwide. Drug-resistant microbes contribute significantly to morbidity and mortality in the hospital, especially in the critical care unit. The primary etiology of increasing antibiotic resistance is inappropriate and excessive use of antibiotics. The alarming rise of drug-resistant microbes worldwide threatens to erode our ability to treat infections with our current armamentarium of antibiotics. Unfortunately, the pace of development of new antibiotics by the pharmaceutical industry has not kept up with rising resistance to expand our options to treat microbial infections. The costs of antibiotic resistance include death and disability, extended hospital stays due to prolonged sickness, need for expensive therapies, rising healthcare expenditure, reduced productivity from time out of the workforce, and rising penury. This review sums up the common mechanisms, trends, and treatment options for hospital-acquired multidrug-resistant microbes.

Metagenomic Research of Infectious Diseases in Archaeological Contexts: Evidence from the Hospital Real de Todos-os-Santos (Portugal)

Syphilis is one of the most exciting diseases explored in paleopathology and, therefore, tracing back its origin and development has provided a prolific debate. The combination of paleopathological data with historical sources, iconography, and archaeological contexts were the primary sources used to reconstruct its historical path. However, there are some limitations to paleopathological diagnosis due to the nature of bone reaction to stimuli. In addition, historical sources are subjected to a bias of social and cultural nature and the knowledge of those who wrote them. Hence, ancient DNA analysis offers the possibility of acquiring proof of cause by identifying pathogens in an organism. We undertook a metagenomic study of a skeleton exhumed from the Royal Hospital of All Saints (Portugal), renowned for treating syphilis from the 16th century onwards. The skeleton had previously been diagnosed with syphilis according to paleopathological analysis. However, the metagenomics analysis showed no presence of the pathogen associated with syphilis (i.e., Treponema pallidum) but revealed pathogenic microorganisms related to respiratory diseases (pneumonia), nonspecific bone infections (osteomyelitis), and oral bacterial pathologies as well as Hansen’s disease (also known as leprosy). The results are exciting and demand a reappraisal of the observed bone changes, recontextualizing their characterization as syphilis related. They prove that past reconstruction of health and disease diagnoses based on assessing human osteological remains of known context (such as a syphilitic hospital) may bias interpretations and, therefore, caution is recommended, not forgetting that the absence of evidence is not evidence of absence (in this case of syphilis) in life.

Multi-drug resistant gram-negative bacterial pneumonia: etiology, risk factors, and drug resistance patterns

Bacterial pneumonia is one of the most serious public health issues owing to its medical and economic costs, which result in increased morbidity and mortality in people of all ages around the world. Furthermore, antimicrobial resistance has risen over time, and the advent of multi-drug resistance in GNB complicates therapy and has a detrimental impact on patient outcomes. The current review aimed to summarize bacterial pneumonia with an emphasis on gram-negative etiology, pathogenesis, risk factors, resistance mechanisms, treatment updates, and vaccine concerns to tackle the problem before it causes a serious consequence. In conclusion, the global prevalence of GNB in CAP was reported 49.7% to 83.1%, whereas in VAP patients ranged between 76.13% to 95.3%. The most commonly reported MDR-GNB causes of pneumonia were A. baumannii, K. pneumoniae, and P. aeruginosa, with A. baumannii isolated particularly in VAP patients and the elderly. In most studies, ampicillin, tetracyclines, amoxicillin-clavulanic acid, cephalosporins, and carbapenems were shown to be highly resistant. Prior MDR-GNB infection, older age, previous use of broad-spectrum antibiotics, high frequency of local antibiotic resistance, prolonged hospital stays, ICU admission, mechanical ventilation, and immunosuppression are associated with the MDR-GNB colonization. S. maltophilia was reported as a severe cause of HAP/VAP in patients with mechanically ventilated and having hematologic malignancy due to its ability of biofilm formation, site adhesion in respiratory devices, and its intrinsic and acquired drug resistance mechanisms. Effective combination therapies targeting PDR strains and drug-resistant genes, antibiofilm agents, gene-based vaccinations, and pathogen-specific lymphocytes should be developed in the future.

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

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

Clinical use of intravenous polymyxin B for the treatment of patients with multidrug-resistant Gram-negative bacterial infections: An evaluation of the current evidence

OBJECTIVES

The epidemic dimensions of the emergence of multidrug-resistant (MDR) Gram-negative bacterial infections have led to the revival of old antibiotics, including the polymyxins.

METHODS

We performed a review and meta-analysis to evaluate the current literature data regarding the effectiveness and safety of intravenous polymyxin B in patients with MDR Gram-negative bacterial infections and the overall mortality and nephrotoxicity in patients treated with intravenous polymyxin B either as monotherapy or combination therapy.

RESULTS

A total of 5 prospective and 28 retrospective studies, 1 cross-sectional study, 2 retrospective case series and 7 case reports provided data regarding the effectiveness and/or toxicity of intravenous polymyxin B. All-cause mortality of 2910 patients (from 27 studies) who received intravenous polymyxin B was 41.2% (95% CI 35.5-47.0%). All-cause nephrotoxicity of 2994 patients (from 28 studies) treated with intravenous polymyxin B was 40.7% (95% CI 35.0-46.6%). Renal failure among 2111 patients (from 14 studies) was 11.2% (95% CI 8.7-13.9%).

CONCLUSION

Mortality of patients treated with intravenous polymyxin B is similar to the literature-reported mortality of patients treated with intravenous colistin, while nephrotoxicity associated with polymyxin B use is possibly milder compared with colistin use based on literature data. Head-to-head prospective studies would help to clarify the benefit of polymyxin B over colistin. However, a critical evaluation of the existing worldwide literature data supports the need for availability of the intravenous formulation of polymyxin B as a potentially useful option for the treatment of patients with MDR and extensively drug-resistant (XDR) Gram-negative bacterial infections.

[Off label uses of tigecycline]

INTRODUCTION

Tigecycline is a relatively new antibiotic that have very limited valid indications. When no other alternative is available, this drug is widely used off label with promising results. The objective of this study is to summarize the different off label uses of tigecycline so that we can decide when and how to prescribe it in the absence of guidelines.

MATERIAL AND METHODS

This study a revue of the literature collecting all the articles concerning the off label uses of tigecycline.

RESULTS

Tigecycline was widely prescribed, off label, to treat infections with controversial results. Randomised clinical trials were conducted to evaluate its use to treat pneumonia. The results for this indication have a respectable level of evidence. For the other indications, the data collected was insufficient to support tigecycline prescription. In fact, different protocols were used which makes it hard to evaluate the efficacy and to conclude to the best treatment regimen. A tendency to prescribe high doses of the molecule was noted in different studies. When prescribed off label, tigecycline prescriptions were associated with a higher mortality and incidence of side effects.

CONCLUSION

The tigecycline remains a valid option for the treatment of infections dues to multi-resistant bacteria especially when other alternatives are scarce or in cases of renal failure.

Hospital-acquired Pneumonia and Ventilator-associated Pneumonia in Children: A Prospective Natural History and Case-Control Study

BACKGROUND

Clinical trials for antibiotics designed to treat hospital-acquired and ventilator-associated bacterial pneumonias (HABP/VABP) are hampered by making these diagnoses in a way that is acceptable to the United States Food and Drug Administration and consistent with standards of care. We examined laboratory and clinical features that might improve pediatric HABP/VABP trial efficiency by identifying risk factors predisposing children to HABP/VABP and describing the epidemiology of pediatric HABP/VABP.

METHODS

We prospectively reviewed the electronic medical records of patients <18 years of age admitted to intensive and intermediate care units (ICUs) if they received qualifying respiratory support or were started on antibiotics for a lower respiratory tract infection or undifferentiated sepsis. Subjects were followed until HABP/VABP was diagnosed or they were discharged from the ICU. Clinical, laboratory and imaging data were abstracted using structured chart review. We calculated HABP/VABP incidence and used a stepwise backward selection multivariable model to identify risk factors associated with development of HABP/VABP.

RESULTS

A total of 862 neonates, infants and children were evaluated for development of HABP/VABP; 10% (82/800) of those receiving respiratory support and 12% (103/862) overall developed HABP/VABP. Increasing age, shorter height/length, longer ICU length of stay, aspiration risk, blood product transfusion in the prior 7 days and frequent suctioning were associated with increased odds of HABP/VABP. The use of noninvasive ventilation and gastric acid suppression were both associated with decreased odds of HABP/VABP.

CONCLUSIONS

Food and Drug Administration-defined HABP/VABP occurred in 10%-12% of pediatric patients admitted to ICUs. Risk factors vary by age group.

Multidrug Resistance (MDR) and Collateral Sensitivity in Bacteria, with Special Attention to Genetic and Evolutionary Aspects and to the Perspectives of Antimicrobial Peptides-A Review

Antibiotic poly-resistance (multidrug-, extreme-, and pan-drug resistance) is controlled by adaptive evolution. Darwinian and Lamarckian interpretations of resistance evolution are discussed. Arguments for, and against, pessimistic forecasts on a fatal “post-antibiotic era” are evaluated. In commensal niches, the appearance of a new antibiotic resistance often reduces fitness, but compensatory mutations may counteract this tendency. The appearance of new antibiotic resistance is frequently accompanied by a collateral sensitivity to other resistances. Organisms with an expanding open pan-genome, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae, can withstand an increased number of resistances by exploiting their evolutionary plasticity and disseminating clonally or poly-clonally. Multidrug-resistant pathogen clones can become predominant under antibiotic stress conditions but, under the influence of negative frequency-dependent selection, are prevented from rising to dominance in a population in a commensal niche. Antimicrobial peptides have a great potential to combat multidrug resistance, since antibiotic-resistant bacteria have shown a high frequency of collateral sensitivity to antimicrobial peptides. In addition, the mobility patterns of antibiotic resistance, and antimicrobial peptide resistance, genes are completely different. The integron trade in commensal niches is fortunately limited by the species-specificity of resistance genes. Hence, we theorize that the suggested post-antibiotic era has not yet come, and indeed might never come.

In vitro activity of fosfomycin against mucoid and non-mucoid Pseudomonas aeruginosa strains

OBJECTIVES

Pseudomonas aeruginosa is the most frequent infectious agent in cystic fibrosis patients. P. aeruginosa resistance to first line antibiotics limits therapeutic options, but the therapeutic potential of older generation antibiotics, such as fosfomycin is under investigation. Fosfomycin does not belong to any other antibiotic class and acts by inhibiting the biosynthesis of the bacterial cell wall during the initial phases. A major problem for the use of fosfomycin against P. aeruginosa is the absence of a clinical breakpoint, the last one of 32 μg/mL was proposed in 2013 by the CA-SFM (Comité de l'Antibiogramme de la Société Française de Microbiologie).

METHODS

Sixty-one strains of P. aeruginosa (thirty mucoid and thirty-one non mucoid) were collected from respiratory samples of cystic fibrosis patients. All isolates were identified by MALDI-TOF (Bruker, Bremen, Germany). Fosfomycin MICs against P. aeruginosa were measured using an automated system and confirmed by the gold standard method.

RESULTS

There was no significant difference between mucoid and non-mucoid strains. MIC distribution and susceptibility rates were obtained by agar dilution method and from this data we measured MIC50 and MIC90 which were equal to 32 μg/mL and 64 μg/mL, respectively. From automated method results we measured a very major error (VME), major error (ME) and categorical agreement (CA) which were equal to 0%, 11% and 89%, respectively. Comparing automated and agar dilution methods, a Cohen's kappa equal to 73% (0.726) was measured.

CONCLUSIONS

Our data suggest that fosfomycin has good effect against mucoid and non-mucoid strains of P. aeruginosa and automated systems can be implemented in clinical microbiology laboratories to assess fosfomycin with rapid and reproducible results.

New Drugs for Multidrug-Resistant Gram-Negative Organisms: Time for Stewardship

A gradual rise in drug-resistant trends among Gram-negative organisms, especially carbapenem-resistant (CR) Enterobacteriaceae (CRE), CR-Pseudomonas aeruginosa, and extensively-drug-resistant (XDR) Acinetobacter baumannii, poses an enormous threat to healthcare systems worldwide. In the last decade, many pharmaceutical companies have devoted enormous resources to the development of new potent antibiotics against XDR Gram-negative pathogens, particularly CRE. Some of these novel antibiotics against CRE strains are β-lactam/β-lactamase-inhibitor combination agents, while others belong to the non-β-lactam class. Most of these antibiotics display good in vitro activity against the producers of Ambler class A, C, and D β-lactamase, although avibactam and vaborbactam are not active in vitro against metallo-β-lactamase (MβL) enzymes. Nevertheless, in vitro efficacy against the producers of some or all class B enzymes (New Delhi MβL, Verona integron-encoded MβL, etc) has been shown with cefepime-zidebactam, aztreonam-avibactam, VNRX-5133, cefiderocol, plazomicin, and eravacycline. As of Feburary 2019, drugs approved for treatment of some CRE-related infections by the US Food and Drug Administration included ceftazidime-avibactam, meropenem-vaborbactam, plazomicin, and eravacycline. Although active against extended-spectrum and AmpC β-lactamase-producing Enterobacteriaceae, delafloxacin does not show in vitro activity against CRE. Murepavadin is shown to be specifically active against CR- and colistin-resistant P. aeruginosa strains. Despite successful development of novel antibiotics, strict implementation of an antibiotic stewardship policy in combination with the use of well-established phenotypic tests and novel multiplex PCR methods for detection of the most commonly encountered β-lactamases/carbapenemases in hospitals is important for prescribing effective antibiotics against CRE and decreasing the resistance burden due to CRE.

Toll-like receptor 4: A promising therapeutic target for pneumonia caused by Gram-negative bacteria

Gram‐negative bacteria (GNB) emerge as important pathogens causing pulmonary infection, which can develop into sepsis due to bacterial resistance to antibiotics. GNB pneumonia poses a huge social and economic burden all over the world. During GNB infection in the lung, Toll‐like receptor 4 (TLR4) can form a complex with MD2 and CD14 after recognizing lipopolysaccharide of GNB, initiate the MyD88‐ and TRIF‐dependent signalling pathways and stimulate host non‐specific immune response. In this review, we summarize recent progress in our understanding of the role of TLR4 in GNB pneumonia. The latest experimental results, especially in TLR4 knockout animals, suggest a promising potential of targeting TLR4 signalling pathway for the treatment of GNB pneumonia. Furthermore, we highlight the benefits of Traditional Chinese Medicine as novel candidates for the therapy of GNB pneumonia due to the modulation of TLR4 signalling pathway. Finally, we discuss the promise and challenge in the development of TLR4‐based drugs for GNB pneumonia.

Reservoirs of resistance: polymyxin resistance in veterinary-associated companion animal isolates of Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa is an opportunistic pathogen and a major cause of infections. Widespread resistance in human infections are increasing the use of last resort antimicrobials such as polymyxins. However, these have been used for decades in veterinary medicine. Companion animals are an understudied source of antimicrobial resistant P. aeruginosa isolates. This study evaluated the susceptibility of P. aeruginosa veterinary isolates to polymyxins to determine whether the veterinary niche represents a potential reservoir of resistance genes for pathogenic bacteria in both animals and humans.

METHODS AND RESULTS

Clinical P. aeruginosa isolates (n=24) from UK companion animals were compared for antimicrobial susceptibility to a panel of human-associated isolates (n=37). Minimum inhibitory concentration (MIC) values for polymyxin B and colistin in the companion animals was significantly higher than in human isolates (P=0.033 and P=0.013, respectively). Genotyping revealed that the veterinary isolates were spread throughout the P. aeruginosa population, with shared array types from human infections such as keratitis and respiratory infections, suggesting the potential for zoonotic transmission. Whole genome sequencing revealed mutations in genes associated with polymyxin resistance and other antimicrobial resistance-related genes.

CONCLUSION

The high levels of resistance to polymyxin shown here, along with genetic similarities between some human and animal isolates, together suggest a need for sustained surveillance of this veterinary niche as a potential reservoir for resistant, clinically relevant bacteria in both animals and humans.

Optimizing Antibiotic Administration for Pneumonia

Pneumonia, including community-acquired bacterial pneumonia, hospital-acquired bacterial pneumonia, and ventilator-acquired bacterial pneumonia, carries unacceptably high morbidity and mortality. Despite advances in antimicrobial therapy, emergence of multidrug resistance and high rates of treatment failure have made optimization of antibiotic efficacy a priority. This review focuses on pharmacokinetic and pharmacodynamic approaches to antibacterial optimization within the lung environment and in the setting of critical illness. Strategies for including these approaches in drug development programs as well as clinical practice are described and reviewed.

Drug Prevention and Control of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is one of the most prevalent and serious complications of mechanical ventilation, which is considered a common nosocomial infection in critically ill patients. There are some great options for the prevention of VAP: (i) minimize ventilator exposure; (ii) intensive oral care; (iii) aspiration of subglottic secretions; (iv) maintain optimal positioning and encourage mobility; and (v) prophylactic probiotics. Furthermore, clinical management of VAP depends on appropriate antimicrobial therapy, which needs to be selected based on individual patient factors, such as previous antibacterial therapy, history of hospitalization or mechanical ventilation, and bacterial pathogens and antibiotic resistance patterns. In fact, antibiotic resistance has exponentially increased over the last decade, and the isolation of a multidrug-resistant (MDR) pathogen has been identified as an independent predictor of inadequate initial antibiotic therapy and which is significantly associated with increased mortality. Multiple attempts were used in the treatment of VAP, such as novel antibacterial agents, inhaled antibiotics and monoclonal antibodies. In this review, we summarize the current therapeutic options for the prevention and treatment of VAP, aiming to better management of VAP in clinical practice.

A Breath of Fresh Air in the Fog of Antimicrobial Resistance: Inhaled Polymyxins for Gram-Negative Pneumonia

Despite advancements in therapy, pneumonia remains the leading cause of death due to infectious diseases. Novel treatment strategies are desperately needed to optimize the antimicrobial therapy of patients suffering from this disease. One such strategy that has recently garnered significant attention is the use of inhaled antibiotics to rapidly achieve therapeutic concentrations directly at the site of infection. In particular, there is significant interest in the role of inhaled polymyxins for the treatment of nosocomial pneumonia, including ventilator-associated pneumonia, due to their retained activity against multi-drug resistant Gram-negative pathogens, including Acinetobacter baumannii and Pseudomonas aeruginosa. This review will provide a comprehensive overview of the pharmacokinetic/pharmacodynamic profile, clinical outcomes, safety, and potential role of inhaled polymyxins in clinical practice.

Phage Lysins for Fighting Bacterial Respiratory Infections: A New Generation of Antimicrobials

Lower respiratory tract infections and tuberculosis are responsible for the death of about 4.5 million people each year and are the main causes of mortality in children under 5 years of age. Streptococcus pneumoniae is the most common bacterial pathogen associated with severe pneumonia, although other Gram-positive and Gram-negative bacteria are involved in respiratory infections as well. The ability of these pathogens to persist and produce infection under the appropriate conditions is also associated with their capacity to form biofilms in the respiratory mucous membranes. Adding to the difficulty of treating biofilm-forming bacteria with antibiotics, many of these strains are becoming multidrug resistant, and thus the alternative therapeutics available for combating this kind of infections are rapidly depleting. Given these concerns, it is urgent to consider other unconventional strategies and, in this regard, phage lysins represent an attractive resource to circumvent some of the current issues in infection treatment. When added exogenously, lysins break specific bonds of the peptidoglycan and have potent bactericidal effects against susceptible bacteria. These enzymes possess interesting features, including that they do not trigger an adverse immune response and raise of resistance is very unlikely. Although Gram-negative bacteria had been considered refractory to these compounds, strategies to overcome this drawback have been developed recently. In this review we describe the most relevant in vitro and in vivo results obtained to date with lysins against bacterial respiratory pathogens.