Cost of nosocomial pneumonia: the example of vancomycin versus linezolid—shorter stay or fewer complications?

Efficacy of Telavancin in Comparison to Linezolid in a Porcine Model of Severe Methicillin-Resistant Staphylococcus aureus Pneumonia

Current guidelines recommend vancomycin and linezolid as first-line agents against methicillin-resistant Staphylococcus aureus (MRSA) nosocomial pneumonia. Telavancin is a potential new therapeutic alternative, specifically in monomicrobial MRSA pneumonia. This study compared the efficacies of telavancin versus linezolid in a porcine model of severe MRSA pneumonia. In 18 mechanically ventilated pigs (32.11 ± 1.18 kg), 75 ml of 10⁶ CFU/ml of MRSA was administered into each pulmonary lobe. After the onset of pneumonia, pigs were randomized into three groups: a control group, a group receiving 22.5 mg/kg of body weight every 24 h (q24h) of telavancin, and a group receiving 10 mg/kg q12h of linezolid intravenously. Tracheal aspirate and bronchoalveolar lavage (BAL) fluids were cultured every 24 h. After 48 h of treatment, tissue samples were collected from the ventral and dorsal sections of each lobe. Microbiological and histopathological analyses were performed. Lung tissue concentrations differed among the groups (P = 0.019), with the lowest MRSA lung burden in the telavancin group (P < 0.05 versus the control). MRSA was detected in 46.7%, 40.0%, and 21.7% of the lung tissue samples from the control, linezolid, and telavancin groups, respectively (P < 0.001). MRSA concentrations differed among the groups in tracheal aspirate fluid (P = 0.011) but not in BAL fluid. Furthermore, there was no increased risk of kidney injury during telavancin use. Thus, telavancin has higher bactericidal efficacy than linezolid during the first 48 h of treatment in a porcine model of severe MRSA pneumonia. However, studies are needed to confirm the benefits of telavancin in treating MRSA nosocomial pneumonia.

Bacteriophages Improve Outcomes in Experimental Staphylococcus aureus Ventilator-associated Pneumonia

Rationale: Infections caused by multidrug-resistant bacteria are a major clinical challenge. Phage therapy is a promising alternative antibacterial strategy.Objectives: To evaluate the efficacy of intravenous phage therapy for the treatment of ventilator-associated pneumonia due to methicillin-resistant Staphylococcus aureus in rats.Methods: In a randomized, blinded, controlled experimental study, we compared intravenous teicoplanin (3 mg/kg, n = 12), a cocktail of four phages (2-3 × 10⁹ plaque-forming units/ml of 2003, 2002, 3A, and K; n = 12), and a combination of both (n = 11) given 2, 12, and 24 hours after induction of pneumonia, and then once daily for 4 days. The primary outcome was survival at Day 4. Secondary outcomes were bacterial and phage densities in lungs and spleen, histopathological scoring of infection within the lungs, and inflammatory biomarkers in blood.Measurements and Main Results: Treatment with either phages or teicoplanin increased survival from 0% to 58% and 50%, respectively (P < 0.005). The combination of phages and antibiotics did not further improve outcomes (45% survival). Animal survival correlated with reduced bacterial burdens in the lung (1.2 × 10⁶ cfu/g of tissue for survivors vs. 1.2 × 10⁹ cfu/g for nonsurviving animals; P < 0.0001), as well as improved histopathological outcomes. Phage multiplication within the lung occurred during treatment. IL-1β increased in all treatment groups over the course of therapy.Conclusions: Phage therapy was as effective as teicoplanin in improving survival and decreasing bacterial load within the lungs of rats infected with methicillin-resistant S. aureus. Combining antibiotics with phage therapy did not further improve outcomes.

Clinical Pharmacokinetics and Pharmacodynamics of Oxazolidinones

Oxazolidinones are a class of synthetic antimicrobial agents with potent activity against a wide range of multidrug-resistant Gram-positive pathogens including methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. Oxazolidinones exhibit their antibacterial effects by inhibiting protein synthesis acting on the ribosomal 50S subunit of the bacteria and thus preventing formation of a functional 70S initiation complex. Currently, two oxazolidinones have been approved by the US Food and Drug Administration: linezolid and more recently tedizolid. Other oxazolidinones are currently under investigation in clinical trials. These antimicrobial agents exhibit a favourable pharmacokinetic profile with an excellent bioavailability and a good tissue and organ penetration. In-vitro susceptibility studies have shown that oxazolidinones are bacteriostatic against enterococci and staphylococci, and bactericidal for the majority of strains of streptococci. In the context of emergence of resistance to glycopeptides, oxazolidinones have become an effective alternative to vancomycin treatment frequently associated with nephrotoxicity. However, oxazolidinones, and linezolid in particular, are associated with significant adverse events, myelosuppression representing the main unfavourable side effect. More recently, tedizolid has been shown to effectively treat acute bacterial skin and skin structure infections. This newer oxazolidinone offers the advantages of once-daily dosing and a better safety profile in healthy volunteer studies (fewer gastrointestinal and haematological side effects). The potential use of tedizolid for other infections that could require longer therapy warrants further studies for positioning this new oxazolidinone in the available antimicrobial armamentarium. Moreover, other oxazolidinones are currently under active investigation.

Valuing antibiotics: The role of the hospital clinician

The global public health threat of antibiotic-resistant infections as well as the lack of new treatments in clinical development is a critical issue. Reasons for this include diminished commercial incentives for pharmaceutical companies to develop new antibiotics, which part-reflects a shift in antibiotic marketing paradigm from broad deployment to targeted therapy in relatively small patient populations. Such changes are encouraged by antimicrobial stewardship (AMS). Other factors include a lack of recognition in the traditional assessment of new antibiotics by regulators, health technology assessors and payers of the broad range of benefits of new agents, particularly their value to health care, economies and society. Recognising the seriousness of the situation, there have been recent changes and proposals by regulators for modification of the assessment process to accommodate a broader range of acceptable data supporting new drug applications. There is also increasing recognition by some payers of the societal benefit of new antibiotics and the need for financial incentives for those developing high-priority antibiotics. However, progress is slow, with recent publications focusing on industry and strategic perspectives rather than clinical implications. In this opinion piece, we therefore focus on clinicians and the practical steps they can take to drive and contribute to increasing awareness and understanding of the value of antibiotics. This includes identifying and gathering appropriate alternative data sources, educating on AMS and prescribing habits, and contributing to international antibiotic susceptibility surveillance models.