Novel Engineered Peptides of a Phage Lysin as Effective Antimicrobials against Multidrug-Resistant Acinetobacter baumannii

Pinto

Appl Microbiol Biotechnol

et al. 2016

Citrobacter spp., although frequently ignored, is emerging as an important nosocomial bacterium able to cause various superficial and systemic life-threatening infections. Considered to be hard-to-treat bacterium due to its pattern of high antibiotic resistance, it is important to develop effective measures for early and efficient therapy. In this study, the first myovirus (vB_CfrM_CfP1) lytic for Citrobacter freundii was microbiologically and genomically characterized. Its morphology, activity spectrum, burst size, and biophysical stability spectrum were determined. CfP1 specifically infects C. freundii, has broad host range (>85 %; 21 strains tested), a burst size of 45 PFU/cell, and is very stable under different temperatures (−20 to 50°C) and pH (3 to 11) values. CfP1 demonstrated to be highly virulent against multidrug-resistant clinical isolates up to 12 antibiotics, including penicillins, cephalosporins, carbapenems, and fluroquinoles. Genomically, CfP1 has a dsDNA molecule with 180,219 bp with average GC content of 43.1 % and codes for 273 CDSs. The genome architecture is organized into function-specific gene clusters typical for tailed phages, sharing 46 to 94 % nucleotide identity to other Citrobacter phages. The lysin gene encoding a predicted D-Ala-D-Ala carboxypeptidase was also cloned and expressed in Escherichia coli and its activity evaluated in terms of pH, ionic strength, and temperature. The lysine optimum activity was reached at 20 mM HEPES, pH 7 at 37°C, and was able to significantly reduce all C. freundii (>2 logs) as well as Citrobacter koseri (>4 logs) strains tested. Interestingly, the antimicrobial activity of this enzyme was performed without the need of pretreatment with outer membrane-destabilizing agents. These results indicate that CfP1 lysin is a good candidate to control problematic Citrobacter infections, for which current antibiotics are no longer effective.

Section: Discussionmentioning

confidence: 99%

Characterization and genome sequencing of a Citrobacter freundii phage CfP1 harboring a lysin active against multidrug-resistant isolates

Pinto

Appl Microbiol Biotechnol

et al. 2016

“…Bacteriophage lysins are classified as peptidoglycan hydrolases, being able to cleave a variety of bonds in the bacterial peptidoglycan. Preliminary in vitro and in vivo studies suggest high efficiency of such peptides to kill A. baumannii , supporting further clinical development [41]. …”

Section: Mdr Bacteriamentioning

confidence: 99%

The intensive care medicine research agenda on multidrug-resistant bacteria, antibiotics, and stewardship

et al. 2017

Purpose: To concisely describe the current standards of care, major recent advances, common beliefs that have been contradicted by recent trials, areas of uncertainty, and clinical studies that need to be performed over the next decade and their expected outcomes with regard to the management of multidrug-resistant (MDR) bacteria, antibiotic use, and antimicrobial stewardship in the intensive care unit (ICU) setting. Methods: Narrative review based on a systematic analysis of the medical literature, national and international guidelines, and expert opinion. Results: The prevalence of infection of critically ill patients by MDR bacteria is rapidly evolving. Clinical studies aimed at improving understanding of the changing patterns of these infections in ICUs are urgently needed. Ideal antibiotic utilization is another area of uncertainty requiring additional investigations aimed at better understanding of dose optimization, duration of therapy, use of combination treatment, aerosolized antibiotics, and the integration of rapid diagnostics as a guide for treatment. Moreover, there is an imperative need to develop non-antibiotic approaches for the prevention and treatment of MDR infections in the ICU. Finally, clinical research aimed at demonstrating the beneficial impact of antimicrobial stewardship in the ICU setting is essential. Conclusions: These and other fundamental questions need to be addressed over the next decade in order to better understand how to prevent, diagnose, and treat MDR bacterial infections. Clinical studies described in this research agenda provide a template and set priorities for investigations that should be performed in this field.

“…Several rodent studies have suggested that strain-specific phages can improve outcomes from intranasally inoculated lung infection, intraperitoneal sepsis, or wound infections (288,(292)(293)(294). Lysin peptides from phages have also been studied as effective treatments for A. baumannii infections in mice (295,296).…”

Section: Bacteriophagesmentioning

confidence: 99%

Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges

et al. 2017

SUMMARY Acinetobacter is a complex genus, and historically, there has been confusion about the existence of multiple species. The species commonly cause nosocomial infections, predominantly aspiration pneumonia and catheter-associated bacteremia, but can also cause soft tissue and urinary tract infections. Community-acquired infections by Acinetobacter spp. are increasingly reported. Transmission of Acinetobacter and subsequent disease is facilitated by the organism's environmental tenacity, resistance to desiccation, and evasion of host immunity. The virulence properties demonstrated by Acinetobacter spp. primarily stem from evasion of rapid clearance by the innate immune system, effectively enabling high bacterial density that triggers lipopolysaccharide (LPS)–Toll-like receptor 4 (TLR4)-mediated sepsis. Capsular polysaccharide is a critical virulence factor that enables immune evasion, while LPS triggers septic shock. However, the primary driver of clinical outcome is antibiotic resistance. Administration of initially effective therapy is key to improving survival, reducing 30-day mortality threefold. Regrettably, due to the high frequency of this organism having an extreme drug resistance (XDR) phenotype, early initiation of effective therapy is a major clinical challenge. Given its high rate of antibiotic resistance and abysmal outcomes (up to 70% mortality rate from infections caused by XDR strains in some case series), new preventative and therapeutic options for Acinetobacter spp. are desperately needed.