Aerosolized antibiotics to treat ventilator-associated pneumonia

Potential for bacteriophage therapy for Staphylococcus aureus pneumonia with influenza A coinfection

The ability of influenza A virus to evolve, coupled with increasing antimicrobial resistance, could trigger an influenza pandemic with great morbidity and mortality. Much of the 1918 influenza pandemic mortality was likely due to bacterial coinfection, including Staphylococcus aureus pneumonia. S. aureus resists many antibiotics. The lack of new antibiotics suggests alternative antimicrobials, such as bacteriophages, are needed. Potential delivery routes for bacteriophage therapy (BT) include inhalation and intravenous injection. BT has recently been used successfully in compassionate access pulmonary infection cases. Phage lysins, enzymes that hydrolyze bacterial cell walls and which are bactericidal, are efficacious in animal pneumonia models. Clinical trials will be needed to determine whether BT can ameliorate disease in influenza and S. aureus coinfection.

Comparison of two therapeutic approaches for the management of ventilator-associated pneumonia due to multidrug-resistant Acinetobacter: a randomized clinical trial study

Management of ventilator-associated pneumonia (VAP) is a puzzling issue for infectious disease specialist. The present clinical trial study was aimed to comparing the effects of injectable colistin plus nebulized colistin and injectable colistin plus nebulized tobramycin on management of patients with VAP due to multidrug-resistant Acinetobacter. VAP patients were randomly divided into two groups (n = 30/each): Group 1 - patients that received intravenous (IV) meropenem, injectable colistin plus nebulized colistin, as a routine treatment, and Group 2 - patients that received IV meropenem, injectable colistin plus nebulized tobramycin. A total of 14 days of therapeutic intervention are required for every case. Follow-up for subjects was performed at five time-points: days 1, 3, 5, 7, and 14 after intervention. Also, a mean of creatinine levels of patients was determined in five times. In the present study, the clinical pulmonary infection score (CPIS) was determined on the basis of points assigned for various clinically manifestations of VAP. Based on our statistical analysis, there was no significant difference between CPIS and creatinine level in both Groups 1 and 2 (p > .05). CPIS and other clinical investigation appeared effectiveness of the treatment with injected colistin plus nebulized tobramycin; on the other hand, the results of present clinical trial showed that aforementioned therapeutic approach can be used as an alternative treatment for the management of infection in VAP patients.

Aerosol Therapy for Pneumonia in the Intensive Care Unit

Antibiotic aerosolization in patients with ventilator-associated pneumonia (VAP) allows very high concentrations of antimicrobial agents in the respiratory secretions, far more than those achievable using the intravenous route. However, data in critically ill patients with pneumonia are limited. Administration of aerosolized antibiotics might increase the likelihood of clinical resolution, but no significant improvements in important outcomes have been consistently documented. Thus, aerosolized antibiotics should be restricted to the treatment of extensively resistant gram-negative pneumonia. In these cases, the use of a vibrating-mesh nebulizer seems to be more efficient, but specific settings and conditions are required to improve lung delivery.

Characteristics of an ideal nebulized antibiotic for the treatment of pneumonia in the intubated patient

Gram-negative pneumonia in patients who are intubated and mechanically ventilated is associated with increased morbidity and mortality as well as higher healthcare costs compared with those who do not have the disease. Intravenous antibiotics are currently the standard of care for pneumonia; however, increasing rates of multidrug resistance and limited penetration of some classes of antimicrobials into the lungs reduce the effectiveness of this treatment option, and current clinical cure rates are variable, while recurrence rates remain high. Inhaled antibiotics may have the potential to improve outcomes in this patient population, but their use is currently restricted by a lack of specifically formulated solutions for inhalation and a limited number of devices designed for the nebulization of antibiotics. In this article, we review the challenges clinicians face in the treatment of pneumonia and discuss the characteristics that would constitute an ideal inhaled drug/device combination. We also review inhaled antibiotic options currently in development for the treatment of pneumonia in patients who are intubated and mechanically ventilated.

Respiratory infections in patients undergoing mechanical ventilation

Lower respiratory tract infections in mechanically ventilated patients are a frequent cause of antibiotic treatment in intensive-care units. These infections present as severe sepsis or septic shock with respiratory dysfunction in intubated patients. Purulent respiratory secretions are needed for diagnosis, but distinguishing between pneumonia and tracheobronchitis is not easy. Both presentations are associated with longlasting mechanical ventilation and extended intensive-care unit stay, providing a rationale for antibiotic treatment initiation. Differentiation of colonisers from true pathogens is difficult, and microbiological data show Staphylococcus aureus and Pseudomonas aeruginosa to be of great concern because of clinical outcomes and therapeutic challenges. Key management issues include identification of the pathogen, choice of initial empirical antibiotic, and decisions with regard to the resolution pattern.

Antibiotic stewardship in the intensive care unit

The rapid emergence and dissemination of antimicrobial-resistant microorganisms in ICUs worldwide constitute a problem of crisis dimensions. The root causes of this problem are multifactorial, but the core issues are clear. The emergence of antibiotic resistance is highly correlated with selective pressure resulting from inappropriate use of these drugs. Appropriate antibiotic stewardship in ICUs includes not only rapid identification and optimal treatment of bacterial infections in these critically ill patients, based on pharmacokinetic-pharmacodynamic characteristics, but also improving our ability to avoid administering unnecessary broad-spectrum antibiotics, shortening the duration of their administration, and reducing the numbers of patients receiving undue antibiotic therapy. Either we will be able to implement such a policy or we and our patients will face an uncontrollable surge of very difficult-to-treat pathogens.

Characterization of a human powered nebulizer compressor for resource poor settings

Background

Respiratory disease accounts for three of the ten leading causes of death worldwide. Many of these diseases can be treated and diagnosed using a nebulizer. Nebulizers can also be used to safely and efficiently deliver vaccines. Unfortunately, commercially available nebulizers are not designed for use in regions of the world where lung disease is most prevalent: they are electricity-dependent, cost-prohibitive, and not built to be reliable in harsh operating conditions or under frequent use.

To overcome these limitations, the Human Powered Nebulizer compressor (HPN) was developed. The HPN does not require electricity; instead airflow is generated manually through a hand-crank or bicycle-style pedal system. A health care worker or other trained individual operates the device while the patient receives treatment.

This study demonstrates functional specifications of the HPN in comparison with a standard commercially available electric jet nebulizer compressor, the DeVilbiss Pulmo-Aide 5650D (Pulmo-Aide).

Methods

Pressure and flow characteristics were measured with a rotameter and pressure transducer, respectively. Volume nebulized by each compressor was determined by mass, and particle size distribution was determined via laser diffraction. The Hudson RCI Micro Mist nebulizer mouthpiece was used with both compressors.

Results

The pressure and flow generated by the HPN and Pulmo-Aide were: 15.17 psi and 10.5 L/min; and 14.65 psi and 11.2 L/min, respectively. The volume of liquid delivered by each was equivalent, 1.097 ± 0.107 mL (mean ± s.e.m., n = 13) for the HPN and 1.092 ± 0.116 mL for the Pulmo-Aide. The average particle size was also equivalent, 5.38 ± 0.040 micrometers (mean ± s.e.m., n = 7) and 5.40 ± 0.025 micrometers, respectively.

Conclusions

Based on these characteristics, the HPN’s performance is equivalent to a popular commercially available electric nebulizer compressor. The findings presented in this paper, combined with the results of two published clinical studies, suggest that the HPN could serve as an important diagnostic and therapeutic tool in the fight against global respiratory health challenges including: tuberculosis, chronic obstructive pulmonary disease, asthma, and lower respiratory infections.

Effect of aerosolized colistin as adjunctive treatment on the outcomes of microbiologically documented ventilator-associated pneumonia caused by colistin-only susceptible gram-negative bacteria

BACKGROUND

The increasing frequency of ventilator-associated pneumonia (VAP) caused by colistin-only susceptible (COS) gram-negative bacteria (GNB) is of great concern. Adjunctive aerosolized (AS) colistin can reportedly increase alveolar levels of the drug without increasing systemic toxicity. Good clinical results have been obtained in patients with cystic fibrosis, but conflicting data have been reported in patients with VAP.

METHODS

We conducted a retrospective, 1:1 matched case-control study to evaluate the efficacy and safety of AS plus IV colistin vs IV colistin alone in 208 patients in the ICU with VAP caused by COS Acinetobacter baumannii, Pseudomonas aeruginosa, or Klebsiella pneumoniae.

RESULTS

Compared with the IV colistin cohort, the AS-IV colistin cohort had a higher clinical cure rate (69.2% vs 54.8%, P = .03) and required fewer days of mechanical ventilation after VAP onset (8 days vs 12 days, P = .001). In the 166 patients with posttreatment cultures, eradication of the causative organism was also more common in the AS-IV colistin group (63.4% vs 50%, P = .08). No between-cohort differences were observed in all-cause ICU mortality, length of ICU stay after VAP onset, or rates of acute kidney injury (AKI) during colistin therapy. Independent predictors of clinical cure were trauma-related ICU admission (P = .01) and combined AS-IV colistin therapy (P = .009). Higher mean Simplified Acute Physiology Score II (P = .002) and Sequential Organ Failure Assessment (P = .05) scores, septic shock (P < .001), and AKI onset during colistin treatment (P = .04) were independently associated with clinical failure.

CONCLUSIONS

Our results suggest that AS colistin might be a beneficial adjunct to IV colistin in the management of VAP caused by COS GNB.

Inhaled antibiotics for lower airway infections

Inhaled antibiotics have been used to treat chronic airway infections since the 1940s. The earliest experience with inhaled antibiotics involved aerosolizing antibiotics designed for parenteral administration. These formulations caused significant bronchial irritation due to added preservatives and nonphysiologic chemical composition. A major therapeutic advance took place in 1997, when tobramycin designed for inhalation was approved by the U.S. Food and Drug Administration (FDA) for use in patients with cystic fibrosis (CF) with chronic Pseudomonas aeruginosa infection. Attracted by the clinical benefits observed in CF and the availability of dry powder antibiotic formulations, there has been a growing interest in the use of inhaled antibiotics in other lower respiratory tract infections, such as non-CF bronchiectasis, ventilator-associated pneumonia, chronic obstructive pulmonary disease, mycobacterial disease, and in the post-lung transplant setting over the past decade. Antibiotics currently marketed for inhalation include nebulized and dry powder forms of tobramycin and colistin and nebulized aztreonam. Although both the U.S. Food and Drug Administration and European Medicines Agency have approved their use in CF, they have not been approved in other disease areas due to lack of supportive clinical trial evidence. Injectable formulations of gentamicin, tobramycin, amikacin, ceftazidime, and amphotericin are currently nebulized "off-label" to manage non-CF bronchiectasis, drug-resistant nontuberculous mycobacterial infections, ventilator-associated pneumonia, and post-transplant airway infections. Future inhaled antibiotic trials must focus on disease areas outside of CF with sample sizes large enough to evaluate clinically important endpoints such as exacerbations. Extrapolating from CF, the impact of eradicating organisms such as P. aeruginosa in non-CF bronchiectasis should also be evaluated.

Delivering antibiotics to the lungs of patients with ventilator-associated pneumonia: an update

Ventilator-associated pneumonia is a serious hospital-acquired infection, with 20-70% crude mortality and 10-40% estimated attributable mortality. Insufficient antibiotic concentrations at the infection site when these drugs are given intravenously may lead to poor outcomes, particularly when difficult-to-treat pathogens are responsible; for example, Pseudomonas aeruginosa, extended spectrum beta lactamase-producing Gram-negative bacilli, Acinetobacter spp. and/or methicillin-resistant Staphylococcus aureus. Direct drug delivery to the infection site via aerosolization combined with intravenous administration achieves concentrations exceeding MICs of the pathogens, even those with impaired susceptibility. Experimental and recent clinical results demonstrated our markedly improved ability to deliver aerosolized antibiotics to the lung with new-generation devices, for example, vibrating-mesh nebulizers. Convincing clinical data from a large randomized trial are still lacking to support the routine administration of aerosolized antibiotics to treat ventilator-associated pneumonia, even though some small-randomized trials' observations are encouraging.

Management and prevention of ventilator-associated pneumonia caused by multidrug-resistant pathogens

Ventilator-associated pneumonia (VAP) due to multidrug-resistant (MDR) pathogens is a leading healthcare-associated infection in mechanically ventilated patients. The incidence of VAP due to MDR pathogens has increased significantly in the last decade. Risk factors for VAP due to MDR organisms include advanced age, immunosuppression, broad-spectrum antibiotic exposure, increased severity of illness, previous hospitalization or residence in a chronic care facility and prolonged duration of invasive mechanical ventilation. Methicillin-resistant Staphylococcus aureus and several different species of Gram-negative bacteria can cause MDR VAP. Especially difficult Gram-negative bacteria include Pseudomonas aeruginosa, Acinetobacter baumannii, carbapenemase-producing Enterobacteraciae and extended-spectrum β-lactamase producing bacteria. Proper management includes selecting appropriate antibiotics, optimizing dosing and using timely de-escalation based on antiimicrobial sensitivity data. Evidence-based strategies to prevent VAP that incorporate multidisciplinary staff education and collaboration are essential to reduce the burden of this disease and associated healthcare costs.

Rational use of aminoglycosides--review and recommendations by the Swedish Reference Group for Antibiotics (SRGA)

The Swedish Reference Group for Antibiotics (SRGA) has carried out a risk-benefit analysis of aminoglycoside treatment based on clinical efficacy, antibacterial spectrum, and synergistic effect with beta-lactam antibiotics, endotoxin release, toxicity, and side effects. In addition, SRGA has considered optimal dosage schedules and advice on serum concentration monitoring, with respect to variability in volume of drug distribution and renal clearance. SRGA recommends that aminoglycoside therapy should be considered in the following situations: (1) progressive severe sepsis and septic shock, in combination with broad-spectrum beta-lactam antibiotics, (2) sepsis without shock, in combination with broad-spectrum beta-lactam antibiotics if the infection is suspected to be caused by multi-resistant Gram-negative pathogens, (3) pyelonephritis, in combination with a beta-lactam or quinolone until culture and susceptibility results are obtained, or as monotherapy if a serious allergy to beta-lactam or quinolone antibiotics exists, (4) serious infections caused by multi-resistant Gram-negative bacteria when other alternatives are lacking, and (5) endocarditis caused by difficult-to-treat pathogens when monotherapy with beta-lactam antibiotics is not sufficient. Amikacin is generally more active against extended-spectrum beta-lactamase (ESBL)-producing and quinolone-resistant Escherichia coli than other aminoglycosides, making it a better option in cases of suspected infection caused by multidrug-resistant Enterobacteriaceae. Based on their resistance data, local drug committees should decide on the choice of first-line aminoglycoside. Unfortunately, aminoglycoside use is rarely followed up with audiometry, and in Sweden we currently have no systematic surveillance of adverse events after aminoglycoside treatment. We recommend routine assessment of adverse effects, including hearing loss and impairment of renal function, if possible at the start and after treatment with aminoglycosides, and that these data should be included in hospital patient safety surveillance and national quality registries.

Use of nebulized antimicrobial agents in burned and mechanically ventilated patients with persistent Acinetobacter baumannii, Pseudomonas aeruginosa, or Enterobacteriacea

BACKGROUND

Nebulized antibiotics are used to locally treat colonizations of multi-resistant organisms. Prior systemic nephrotoxic antibiotic use with serum creatinine rises warranted an alternative therapy in 69 ventilator-dependent patients with persisting sputum cultures and need for ventilatory support.

MATERIALS AND METHODS

Following IRB approval, retrospective patient data were reviewed. Analysis included comparison of these 69 patients (71 treatments) to 142 Gram-negative infected burn patients matched for age and burn size.

RESULTS

Mean pooled age and burn wound percent for the 71 triplicates (n=211 patients) were 55.6±18.3 years and 27.4±22.3% burns. Fifty-seven of 69 (83%) patients had inhalation injuries and 54 of 69 (78%) patients survived. Nebulizations averaged 6.8±3.3 days (range 3-12 days). Serum creatinine rose in 2 patients receiving colistimethate nebulizations, known to cause nephrotoxicity following nebulization. Triplicate comparisons via ANOVA noted prolonged ventilatory support (F=13.39; p≪0.05) and length of stay (F=6.11; p≪0.5). Variance was attributed to the sicker nebulized patients. Twenty-four inhalation injury-only triplicates further confirmed that nebulized patient subgroup was more ill.

CONCLUSION

Short duration antibiotic nebulization may allow higher intra-tracheal antibiotic concentrations and may facilitate weaning from the ventilator by reducing bacterial bioburden.

Ventilator-associated pneumonia: a comprehensive review

Ventilator-associated pneumonia (VAP) is the most frequent and severe infection acquired in the intensive care unit, leading to prolonged mechanical ventilation and excess mortality. This article reviews the different aspects of VAP, such as risk factors, causative agents, and approaches to diagnosis, treatment, and prevention. Several aspects of VAP are still considered controversial.

Inhaled antibiotic therapy for ventilator-associated tracheobronchitis and ventilator-associated pneumonia: an update

Ventilator-associated pneumonia (VAP) remains a leading cause of morbidity and mortality in mechanically-ventilated patients in the Intensive Care Unit (ICU). Ventilator-associated tracheobronchitis (VAT) was previously believed to be an intermediate stage between colonization of the lower respiratory tract and VAP. More recent data, however, suggest that VAT may be a separate entity that increases morbidity and mortality, independently of the occurrence of VAP. Some, but not all, patients with VAT progress to develop VAP. Although inhaled antibiotics alone could be effective for the treatment of VAP, the current consensus of opinion favors their role as adjuncts to systemic antimicrobial therapy for VAP. Inhaled antibiotics are increasingly employed for salvage therapy in patients with VAP due to multi-drug resistant Gram-negative bacteria. In contrast to VAP, VAT could be effectively treated with inhaled antibiotic therapy alone or in combination with systemic antimicrobials.

Prevention and management of ventilator-associated pneumonia: A survey on current practices by intensivists practicing in the Indian subcontinent

Implementation of evidence-based guidelines to prevent and manage ventilator-associated pneumonia (VAP) in the clinical setting may not be adequate. We aimed to assess the implementation of selected VAP prevention strategies, and to learn how VAP is managed by the intensivists practicing in the Indian Subcontinent. Three hundred 10-point questionnaires were distributed during an International Critical Care Conferenceheld at New Delhi in 2009. A total of 126 (42%) questionnaires distributed among delegates from India, Nepal and Sri Lanka were analyzed. Majority (96.8%) reported using VAP bundles with a high proportion including head elevation (98.4%), chlorhexidine mouthcare (83.3%), stress ulcer prophylaxis (96.8%), heat and moisture exchangers (HME, 92.9%), early weaning (94.4%), and hand washing (97.6%) as part of their VAP bundle. Use of subglottic secretion drainage (SSD, 45.2%) and closed suction systems (CSS, 74.6%) was also reported by many intensivists, whereas use of selective gut decontamination was reported by only 22.2%. Commonest method for sampling was endotracheal suction by 68.3%. Gram negative organisms were reported to be the most commonly isolated. Majority (39.7%) reported using proton pump inhibitors for stress ulcer prophylaxis and 84.1% believed that VAP contributed to increased mortality. De-escalating therapy was considered in patients responding to treatment by 57.9% and 65.9% considered adding empirical methicillin resistant Staphylococcus aureus (MRSA)coverage, while 63.5% considered adding nebulized antibiotics in certain high-risk patients. There was good concordance regarding VAP prophylaxis among the intensivists with a majority adhering to evidence-based guidelines. We could identify certain issues like the choice of agent for stress ulcer prophylaxis, use of HME filters, SSD and CSS, where there still exists some practice variability and opportunities for improvement.

[Antibiotic treatment of nosocomial pneumonia]

Nosocomial pneumonia is one of the most common infectious diseases acquired in hospital and is often caused by resistant pathogens. For treatment of nosocomial pneumonia an appropriate initial antibiotic therapy is essential and exact knowledge of the specific pathogen spectrum is essential for the correct choice of the empirically calculated antibiotics. In line with a critical reevaluation of the primary treatment, pathogen-specific de-escalation therapy, a diagnosis of possible pulmonary complications (e. g. pleural empyema) and the identification and appropriate rehabilitation measures of non-pulmonary infections are necessary. To attain the best possible outcome the respective therapy concept needs to be adjusted to the individual risk characteristics. Appropriate initial antibiotic therapy, duration of mechanical ventilation and comorbidities are the key factors for patient outcome. This approach helps to avoid the development of resistant pathogens and saves economic resources.

Year in review 2009: Critical Care--infection

In 2009 Critical Care provided important and clinically relevant research data for management and prevention of infections in critically ill patients. The present review summarises the results of these observational studies and clinical trials and discusses them in the context of the current relevant scientific and clinical background. In particular, we discuss recent epidemiologic data on nosocomial infections in intensive care units, present new approaches to prevention of ventilator-associated pneumonia, describe recent advances in biomarker-guided antibiotic stewardship and attempt to briefly summarise specific challenges related to the management of infections caused by multidrug-resistant microorganisms and influenza A (H1N1).

Method to introduce mannitol powder to intubated patients to improve sputum clearance

BACKGROUND

Poor sputum clearance is a common problem encountered in intubated patients, which may cause airway obstruction, hypoxaemia, and increased risk of lower respiratory tract infection. This may result in longer intensive care unit (ICU) stay or even death. Dry powder mannitol has been shown to improve sputum clearance, and thus we developed a system to deliver it to intubated patients.

METHODS

This delivery system consists of a standard adult manual ventilation bag, a one-way duck-billed valve, and a dry powder inhaler (Osmohaler™) contained within a delivery chamber to allow positive pressure ventilation, which in turn, is connected in series to an endotracheal or tracheostomy tube. The aerosol is delivered by compressing the ventilation bag in a reproducible manner to generate positive pressure airflow to disperse the powder into the tracheal tube. We tested the powder output and characteristics of the powder in vitro from two endotracheal tubes (7.0 and 8.5 mm in diameter, 300 mm in length), and two tracheostomy tubes (7.0 mm in diameter and 95 mm in length; 90 mm in diameter and 115 mm in length).

RESULTS AND CONCLUSIONS

Approximately 50 to 60% of the loaded dose of dry powder mannitol is delivered to the distal end of the tracheal tubes for both 4 × 40-mg and 4 × 80-mg capsules. The fine particle fraction (particles smaller than 5 μm) ranges from 20 to 31% of the loaded dose. Powder was emptied from each 40- and 80-mg capsule within 5 ± 1 puffs and 6 ± 1 puffs, respectively. This delivery system has been shown to consistently deliver a very high dose of powder with a favourable fine particle fraction to the distal end of a number of tracheal tubes. This has the potential for a number of clinical therapeutic applications in critically ill patients.

Aerosolized antibiotics in critically ill ventilated patients

PURPOSE OF REVIEW

This review will summarize recent clinical data examining the efficacy of aerosolized antimicrobial therapy in treating respiratory tract infections in mechanically ventilated patients in the ICU.

RECENT FINDINGS

Aerosolized antibiotics provide high levels of drug in the lung and reduce the systemic toxicity associated with intravenous antibiotics. First introduced in the 1970s as a form of prophylaxis for ventilator-associated pneumonia (VAP), now, more than 30 years later, there is a resurgence of interest in using this mode of delivery as primary or adjunctive treatment for ventilator-associated tracheobronchitis (VAT) or VAP. Increasingly resistant organisms are colonizing and infecting critically ill patients, and direct delivery of antibiotic to the lung is being re-evaluated as a means to treat these highly resistant organisms that may not respond to systemic therapy. There are new data emerging that suggest these agents may effectively treat these pathogens when used in targeted, time limited protocols.

SUMMARY

Aerosolized antibiotic therapy may provide an efficacious means of treating respiratory tract infection when targeted at mechanically ventilated patients with proximal airway infection, VAT (with or without VAP) and with highly resistant organisms.

Multidrug-resistant Gram-negative infections: what are the treatment options?

The emergence of multidrug-resistant (MDR) Gram-negative bacilli creates a challenge in the treatment of nosocomial infections. While the pharmaceutical pipeline is waning, two revived old antibacterials (colistin and fosfomycin), a newer one (tigecycline) and an 'improved' member of an existing class (doripenem) are the only therapeutic options left. The class of polymyxins, known since 1947 and represented mostly by polymyxin B and polymyxin E (colistin), has recently gained a principal role in the treatment of the most problematic MDR Gram-negative pathogens (such as Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae and Stenotrophomonas maltophilia). Future prospective studies are needed to answer important clinical questions, such as the possible benefit of combination with other antimicrobials versus monotherapy, the efficacy of colistin in neutropenic hosts and the role of inhaled colistin. As new pharmacokinetic data emerge, clarification of the pharmacokinetic/pharmacodynamic (PK/PD) profile of colistin as well as appropriate dosing seems urgent, while development of resistance must be carefully monitored. Fosfomycin tromethamine, a synthetic salt of fosfomycin discovered in 1969, has regained attention because of its in vitro activity against extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae and MDR P. aeruginosa. Although in use for decades in oral and parenteral formulations for a variety of infections without significant toxicity, its clinical utility in MDR infections remains to be explored in future studies. Tigecycline, the first representative of the new class of glycylcyclines, holds promise in infections from MDR K. pneumoniae (K. pneumoniae carbapenemase [KPC]- and ESBL-producing strains) and Enterobacteriaceae with various mechanisms of resistance. The in vitro activity of tigecycline against A. baumannii makes it a tempting option, as it is currently the most active compound against MDR strains along with colistin. However, the usual minimum inhibitory concentration values of this pathogen are approximately 2 mg/L and compromise clinical outcomes based on PK/PD issues. Its advantageous penetration into various tissues is useful in infections of the skin and soft tissues as well as intra-abdominal infections (official indications), whereas low serum concentrations compromise its use in bloodstream infections. Therefore, prospective studies with dose escalation are urgently needed, as well as clarification of its role in nosocomial pneumonia, after poor results in the study of ventilator-associated pneumonia. Finally, doripenem, the recently licensed member of the carbapenems (without significant spectrum alterations from the ascendant members) seems to possess a lower potential for resistance selection and a more favourable pharmacokinetic profile when given as an extended infusion. The latter strategy could prove helpful in overcoming low level resistance of A. baumannii and P. aeruginosa strains.