In Vitro and In Vivo Evaluations of the Activities of Lauric Acid Monoester Formulations against Staphylococcus aureus

182

144

Methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pyogenes (group A streptococcus [GrAS]) cause serious and sometimes fatal human diseases. They are among the many Gram-positive pathogens for which resistance to leading antibiotics has emerged. As a result, alternative therapies need to be developed to combat these pathogens. We have identified a novel bacteriophage lysin (PlySs2), derived from a Streptococcus suis phage, with broad lytic activity against MRSA, vancomycin-intermediate S. aureus (VISA), Streptococcus suis, Listeria, Staphylococcus simulans, Staphylococcus epidermidis, Streptococcus equi, Streptococcus agalactiae (group B streptococcus [GBS]), S. pyogenes, Streptococcus sanguinis, group G streptococci (GGS), group E streptococci (GES), and Streptococcus pneumoniae. PlySs2 has an N-terminal cysteine-histidine aminopeptidase (CHAP) catalytic domain and a C-terminal SH3b binding domain. It is stable at 50°C for 30 min, 37°C for >24 h, 4°C for 15 days, and ؊80°C for >7 months; it maintained full activity after 10 freeze-thaw cycles. PlySs2 at 128 g/ml in vitro reduced MRSA and S. pyogenes growth by 5 logs and 3 logs within 1 h, respectively, and exhibited a MIC of 16 g/ml for MRSA. A single, 2-mg dose of PlySs2 protected 92% (22/24) of the mice in a bacteremia model of mixed MRSA and S. pyogenes infection. Serially increasing exposure of MRSA and S. pyogenes to PlySs2 or mupirocin resulted in no observed resistance to PlySs2 and resistance to mupirocin. To date, no other lysin has shown such notable broad lytic activity, stability, and efficacy against multiple, leading, human bacterial pathogens; as such, PlySs2 has all the characteristics to be an effective therapeutic.

Section: Methodsmentioning

confidence: 99%

Novel Bacteriophage Lysin with Broad Lytic Activity Protects against Mixed Infection by Streptococcus pyogenes and Methicillin-Resistant Staphylococcus aureus

Gilmer

Schmitz

Euler

et al. 2013

182

144

“…This experiment was repeated for eight consecutive rounds with a doubling of the ClyS concentration incubated with MHB on each successive day, until 4ϫ the ClyS MIC was used on day 8. The experiments were repeated in the same manner for mupirocin at concentrations 1/32ϫ to 4ϫ MIC as described by Rouse et al (27). Experiments for determination of resistance development were repeated using strain 8325-4.…”

Section: Methodsmentioning

confidence: 99%

A Novel Chimeric Lysin Shows Superiority to Mupirocin for Skin Decolonization of Methicillin-Resistant and -Sensitive Staphylococcus aureus Strains

Pastagia

Euler

Chahales

et al. 2011

176

146

Staphylococcus aureus is a major human pathogen responsible for a number of serious and sometimes fatal infections. One of its reservoirs on the human body is the skin, which is known to be a source of invasive infection. The potential for an engineered staphylococcus-specific phage lysin (ClyS) to be used for topical decolonization is presented. We formulated ClyS into an ointment and applied it to a mouse model of skin colonization/infection with S. aureus. Unlike the standard topical antibacterial agent mupirocin, ClyS eradicated a significantly greater number of methicillin-susceptible S. aureus (MSSA) and -resistant S. aureus (MRSA) bacteria: a 3-log reduction with ClyS as opposed to a 2-log reduction with mupirocin in our model. The use of ClyS also demonstrated a decreased potential for the development of resistance by MRSA and MSSA organisms compared to that from the use of mupirocin in vitro. Because antibodies may affect enzyme function, we tested antibodies developed after repeated ClyS exposure for their effect on ClyS killing ability. Our results showed no inhibition of ClyS activity at various antibody titers. These data demonstrate the potential of developing ClyS as a novel class of topical antimicrobial agents specific to staphylococcus.

“…3A) (53). However, two mice displayed uncharacteristically high burdens; upon testing, these isolates were found to exhibit an 4-fold increase in mupirocin resistance (MIC of 0.5 g ml Ϫ1 ) compared to the inoculating strain as well as isolates from the other animals within the treatment group (MIC of 0.125 g ml Ϫ1 ), suggesting that mupirocin alone selected for low-level resistant derivatives.…”

Section: Agents That Potentiate the Antimicrobial Activity Of Mupirocinmentioning

confidence: 99%

“…Despite displaying a high-level mupirocinresistant phenotype, the strain exhibited a moderate reduction in burden (0.54-log-unit reduction) following mupirocin (alone) treatment, a 0.9-log-unit reduction in 1% neomycin-treated animals and a 1.2-log-unit reduction following combination treat- ment. The observed improved activity of the combination toward each strain, combined with the notoriously low resolution of the nasal models available (45,53,54), prompted us to evaluate the combination's ability to reduce S. aureus wound site colonization.…”

Section: Agents That Potentiate the Antimicrobial Activity Of Mupirocinmentioning

confidence: 99%

Neomycin Sulfate Improves the Antimicrobial Activity of Mupirocin-Based Antibacterial Ointments

Blanchard

Brooks

Beckley

et al. 2016

In the midst of the current antimicrobial pipeline void, alternative approaches are needed to reduce the incidence of infection and decrease reliance on last-resort antibiotics for the therapeutic intervention of bacterial pathogens. In that regard, mupirocin ointment-based decolonization and wound maintenance practices have proven effective in reducing Staphylococcus aureus transmission and mitigating invasive disease. However, the emergence of mupirocin-resistant strains has compromised the agent's efficacy, necessitating new strategies for the prevention of staphylococcal infections. Herein, we set out to improve the performance of mupirocin-based ointments. A screen of a Food and Drug Administration (FDA)-approved drug library revealed that the antibiotic neomycin sulfate potentiates the antimicrobial activity of mupirocin, whereas other library antibiotics did not. Preliminary mechanism of action studies indicate that neomycin's potentiating activity may be mediated by inhibition of the organism's RNase P function, an enzyme that is believed to participate in the tRNA processing pathway immediately upstream of the primary target of mupirocin. The improved antimicrobial activity of neomycin and mupirocin was maintained in ointment formulations and reduced S. aureus bacterial burden in murine models of nasal colonization and wound site infections. Combination therapy improved upon the effects of either agent alone and was effective in the treatment of contemporary methicillin-susceptible, methicillin-resistant, and high-level mupirocin-resistant S. aureus strains. From these perspectives, combination mupirocin-and-neomycin ointments appear to be superior to that of mupirocin alone and warrant further development.