Decolonization of Human Anterior Nares of Staphylococcus aureus with Use of a Glycerol Monolaurate Nonaqueous Gel

ABSTRACT Staphylococcus aureus is a highly significant infection problem in health care centers, particularly after surgery. It has been shown that nearly 80% of S. aureus infections following surgery are the same as those in the anterior nares of patients, suggesting that the anterior nares is the source of the infection strain. This has led to the use of mupirocin ointment being applied nasally to reduce infections; mupirocin resistance is being observed. This study was undertaken to determine whether gel composed of 5% glycerol monolaurate solubilized in a glycol-based, nonaqueous gel (5% GML gel) could be used as an alternative. In our study, 40 healthy human volunteers swabbed their anterior nares for 3 days with the 5% GML gel. Prior to swabbing and 8 to 12 h after swabbing, S. aureus and coagulase-negative staphylococcal CFU per milliliter were determined by plating the swabs on mannitol salt agar. Fourteen of the volunteers had S. aureus in their nares prior to 5% GML gel treatment, most persons with the organisms present in both nares; five had pure cultures of S. aureus. All participants without pure culture of S. aureus were cocolonized with S. aureus and coagulase-negative staphylococci. Five of the S. aureus strains produced the superantigens commonly associated with toxic shock syndrome, though none of the participants became ill. For both S. aureus and coagulase-negative staphylococci, the 5% GML gel treatment resulted in a 3-log-unit reduction in microorganisms. For S. aureus, the reduction persisted for 2 or 3 days. IMPORTANCE In this microflora study, we show that a 5% glycerol monolaurate nonaqueous gel is safe for use in the anterior nares. The gel was effective in reducing Staphylococcus aureus nasally, a highly significant hospital-associated pathogen. The gel may be a useful alternative or additive to mupirocin ointment for nasal use prior to surgery, noting that 80% of hospital-associated S. aureus infections are due to the same organism found in the nose. This gel also kills all enveloped viruses tested and should be considered for studies to reduce infection and transmission of coronaviruses and influenza viruses.

Glycerol Monolaurate (GML) and a Nonaqueous Five-Percent GML Gel Kill Bacillus and Clostridium Spores

ABSTRACT Glycerol monolaurate is a broadly antimicrobial fatty acid monoester, killing bacteria, fungi, and enveloped viruses. The compound kills stationary-phase cultures of Bacillus anthracis, suggesting that the molecule may kill spores. In this study, we examined the ability of glycerol monolaurate alone or solubilized in a nonaqueous gel to kill vegetative cells and spores of aerobic B. anthracis, B. subtilis, and B. cereus and anaerobic Clostridium perfringens and Clostridium (Clostridioides) difficile. Glycerol monolaurate alone was bactericidal for all five organisms tested. Glycerol monolaurate alone was effective in killing spores. When solubilized in a nonaqueous gel, the glycerol monolaurate gel was bactericidal for all spores tested. The data suggest that glycerol monolaurate nonaqueous gel could be effective in decontaminating environmental and body surfaces, such as skin. IMPORTANCE Bacillus and Clostridium spores are known to be highly resistant to killing, persisting on environmental and human body surfaces for long periods of time. In favorable environments, these spores may germinate and cause human diseases. It is thus important to identify agents that can be used on both environmental and human skin and mucosal surfaces and that are effective in killing spores. We previously showed that the fatty acid monoester glycerol monolaurate (GML) kills stationary-phase cultures of Bacillus anthracis. Since such cultures are likely to contain spores, it is possible that GML and a human-use-approved GML nonaqueous gel would kill Bacillus and Clostridium spores. The significance of our studies is that we have identified GML, and, to a greater extent, GML solubilized in a nonaqueous gel, as effective in killing spores from both bacterial genera.

Freeze-fracture Transmission Electron Microscopy (FF/TEM) studies of systems containing self-associated structures

Freeze-fracture transmission electron microscopy (FF/TEM) is a well-established and highly-valued technique, often employed in the study of biological systems which are extremely sensitive to structural alteration (e.g., membranes and tissues). The technique relies on rapid specimen cooling to immobilize detailed microstructure, usually in a hydrated environment, prior to fracture and subsequent surface replication. As Zasadzinski and Bailey point out, though, the principle governing this technique is general and can be applied with equal success to the study of “microstructured” or “complex” fluids, i.e., fluids consisting of self-organized supramolecular structures. In this vein, FF/TEM constitutes a powerful means of characterizing the structural attributes of dispersions, emulsions, gels, and liquid crystalline assemblies at relatively high spatial resolution. Such morphological information can prove valuable in the development of the structure-viscosity relationships needed in processing. Here, we demonstrate the utility of FF/TEM in elucidating the role of self-associated structures in three different systems: a chemical reaction environment, a high-internal-phase emulsion, and a nonaqueous gel.