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Staphylococcus aureus, an opportunistic pathogen, causes diverse community and nosocomial-acquired human infections, including folliculitis, impetigo, sepsis, septic arthritis, endocarditis, osteomyelitis, implant-associated biofilm infections and contagious mastitis in cattle. In recent days, both methicillin-sensitive and methicillin-resistant S. aureus infections have increased. Highly effective anti-staphylococcal agents are urgently required. Lysostaphin is a 27 kDa zinc metallo antimicrobial lytic enzyme that is produced by Staphylococcus simulans biovar staphylolyticus and was first discovered in the 1960s. Lysostaphin is highly active against S. aureus strains irrespective of their drug-resistant patterns with a minimum inhibitory concentration of ranges between 0·001 and 0·064 μg ml-1 . Lysostaphin has activity against both dividing and non-dividing S. aureus cells; and can seep through the extracellular matrix to kill the biofilm embedded S. aureus. In spite of having excellent anti-staphylococcal activity, its clinical application is hindered because of its immunogenicity and reduced bio-availability. Extensive research with lysostaphin lead to the development of several engineered lysostaphin derivatives with reduced immunogenicity and increased serum half-life. Therapeutic efficacy of both native and engineered lysostaphin derivatives was studied by several research groups. This review provides an overview of the therapeutic applications of native and engineered lysostaphin derivatives developed to eradicate S. aureus infections.

Aims: To develop an efficient purification strategy for the bacteriophage lysin CHAPK. To evaluate its antibacterial spectrum, enzymatic properties, optimal reaction conditions and lytic activity against live Staphlyococcus aureus. Methods and Results: Recombinant CHAPK was purified to homogeneity by cation exchange chromatography, with yields of up to 10 mg from 1 l of Escherichia coli culture. The lytic spectrum of CHAPK includes all staphylococcal species and also members of the genera Micrcococcus, Streptococcus, Nesterenkonia, Arthrobacter, Leuconostoc and Carnobacterium. The enzyme was active from pH 6 to 11 with an optimum activity at pH 9, from 5 to 40°C, with an optimum activity at 15°C. When cell lysis by CHAPK and lysostaphin was compared over a concentration range of 2·5–10 μg ml−1 using live Staph. aureus for 5 min at 37°C, CHAPK gave rise to greater turbidity reduction indicating that it works more rapidly than lysostaphin. Conclusions: This study describes in detail the purification and characteristics of the novel phage-derived enzyme CHAPK demonstrating that it has excellent biochemical properties as an anti-staphylococcal agent. Significance and Impact of the Study: Currently, there is a need for new antimicrobial agents due to the increasing worldwide prevalence of antibiotic resistance. Our findings demonstrate the potential for development of CHAPK as an alternative therapeutic against pathogenic staphylococci including MRSA.

Aims The biofilm produced by Staphylococcus aureus isolates involved in clinical or subclinical bovine mastitis and the activity of nisin and lysostaphin against the preformed biofilm produced by these strains were investigated. Methods and results Eighteen strains were tested and all produced biofilm. Eight strains with distinct biofilm composition were selected for the antimicrobial activity assays. The minimal inhibitory concentration of each bacteriocin was determined against the planktonic cells and ranged from 15·6 to 500 μg ml(-1) for nisin, and from 3·9 to 50 μg ml(-1) , for lysostaphin. Lysostaphin treatment (0·4 μg ml(-1) ) for 4 h caused a strong Staph. aureus 4181 biofilm detachment and death of the majority of the sessile cells, while nisin treatment (100 μg ml(-1) ) for the same time caused only a great reduction in cell viability. Additionally, combination of both bacteriocins for 4 h resulted in significant death of the sessile cells but no biofilm detachment. Conclusions The treatment with lysostaphin alone or in combination with nisin was effective in killing most biofilm sessile cells. Significance and impact of the study The action of lysostaphin, either alone or in combination with nisin, against established staphylococcal biofilm may represent an alternative to bovine mastitis control. However, the duration of the treatment should be considered for its application so that the best effectiveness can be achieved.

Aims The development of technology for preparing chitosan-protein scaffolds loaded with lysostaphin, which potentially could be used as dressing for wound treatment and soft tissue infections caused by Staphylococcus aureus. Methods and results The unique technology of chitosan solubilization using gaseous CO(2) instead of organic or inorganic acids was used for the incorporation of lysostaphin, the enzyme that exhibits bactericidal activity against staphylococci, within the structure of chitosan-protein sponges. The developed chitosan-protein scaffolds loaded with lysostaphin revealed high antistaphylococcal activity, which has been confirmed with a large (n = 143) collection of clinical (skin and wound infections) and animal (bovine mastitis) isolates of these bacteria, including MRSA. No change of bactericidal activity of the lyophilized materials has been observed during half-year storage at 4°C. Conclusions The developed materials are potential candidates for preparing biologically active, antistaphylococcal wound dressing materials. Significance and impact of the study Staphylococci belong to the most popular and most burdensome aetiological factors of wound and soft tissues infections. The developed chitosan-protein scaffolds loaded with lysostaphin could be a possible solution to problems associated with treatment of these infections.

To develop an efficient purification strategy for the bacteriophage lysin CHAP(K) . To evaluate its antibacterial spectrum(,) enzymatic properties, optimal reaction conditions and lytic activity against live Staphlyococcus aureus.Recombinant CHAP(K) was purified to homogeneity by cation exchange chromatography, with yields of up to 10 mg from 1 l of Escherichia coli culture. The lytic spectrum of CHAP(K) includes all staphylococcal species and also members of the genera Micrcococcus, Streptococcus, Nesterenkonia, Arthrobacter, Leuconostoc and Carnobacterium. The enzyme was active from pH 6 to 11 with an optimum activity at pH 9, from 5 to 40°C, with an optimum activity at 15°C. When cell lysis by CHAP(K) and lysostaphin was compared over a concentration range of 2·5-10 μg ml⁻¹ using live Staph. aureus for 5 min at 37°C, CHAP(K) gave rise to greater turbidity reduction indicating that it works more rapidly than lysostaphin.This study describes in detail the purification and characteristics of the novel phage-derived enzyme CHAP(K) demonstrating that it has excellent biochemical properties as an anti-staphylococcal agent.Currently, there is a need for new antimicrobial agents due to the increasing worldwide prevalence of antibiotic resistance. Our findings demonstrate the potential for development of CHAP(K) as an alternative therapeutic against pathogenic staphylococci including MRSA.

Aims: To characterize the antibacterial synergy of the antimicrobial peptide, ranalexin, used in combination with the anti-staphylococcal endopeptidase, lysostaphin, against methicillin-resistant Staphylococcus aureus (MRSA), and to assess the combination’s potential as a topical disinfectant or decolonizing agent for MRSA. MRSA causes potentially lethal infections, and pre-operative patients colonized with MRSA are often treated with chlorhexidine digluconate and mupirocin cream to eradicate carriage. However, chlorhexidine is unsuitable for some patients, and mupirocin resistance is increasingly encountered, indicating new agents are required. Methods and Results: Using an ex vivo assay, ranalexin and lysostaphin tested in combination reduced viable MRSA on human skin to a greater extent than either compound individually. The combination killed bacteria within 5 min and remained effective and synergistic even in high salt and low pH conditions. Conclusions: The combination is active against MRSA on human skin and under conditions that may be encountered in sweat. Significance and Impact of the Study: Although the exact mechanism of activity remains unresolved, considering its specific spectrum of activity, fast killing kinetics and low likelihood of resistance arising, the combination of ranalexin with lysostaphin warrants consideration as a new agent to eradicate nasal and skin carriage of Staph. aureus, including MRSA.