Synergistic evaluation of Moringa oleifera extract and ß-lactam antibiotic to restore the susceptibility of methicillin-resistant Staphylococcus aureus.

INTRODUCTION: The antibiotic resistance has become a major threat to global health. The combinatorial use of two or more compounds to develop a new formulation may overcome the emerging cases of drug resistance. Moringa oleifera has been utilized as a strong nutritional, immunomodulator and therapeutic agent for decades. In this study, different parts of Moringa oleifera were screened for bioactive compounds that can act as a resistance modifying agent for multi-drug resistant organisms (MDROs). METHODOLOGY: Initially, the combined effect of stem bark extracts and ampicillin was calculated by checkerboard assay. Active compounds of effective extract were assessed by High Performance Liquid Chromatography (HPLC). Minimal Inhibitory Concentration (MIC) and Fractional Inhibitory Concentration Index (FICI) were calculated to evaluate the synergistic behavior of stem bark extract with ampicillin. To study the blocking of resistance pathways of Methicillin-Resistant Staphylococcus aureus (MRSA) western blot was performed. RESULTS: The results revealed that stem bark has significant anti-MRSA activity. The methanolic extract of stem bark in combination with ampicillin showed the highest synergistic effect (FICI value ≤ 0.237) against MRSA. Killing kinetics and membrane potential of ampicillin alone and in combination revealed an increase in the inhibitory potential of ampicillin against MRSA. Decolourization in iodometric assay confirmed the inhibition of ß-lactamase, western blot results confirmed the blocking of penicillin-binding protein (PBP2a) expression with the restoration of MRSA sensitivity against ß-lactams. CONCLUSION: It can be concluded that methanolic extract of Moringa oleifera stem bark has bioactive compounds and can be used as an adjuvant with antibiotics to modify the resistance of MDROs.

In Silico Characterization of the Interaction between the PBP2a "Decoy" Protein of Resistant Staphylococcus aureus and the Monomeric Units of Eudragit E-100 and Poly(Maleic Acid-alt-Octadecene) Polymers.

Antimicrobial treatment alternatives for methicillin-resistant Staphylococcus aureus (MRSA) are increasingly limited. MRSA strains are resistant to methicillin due to the formation of ß-lactamase enzymes, as well as the acquisition of the mecA gene, which encodes the penicillin-binding protein (PBP2a) that reduces the affinity for ß-lactam drugs. Previous studies have shown that the use of ampicillin-loaded nanoparticles can improve antimicrobial activity on resistant S. aureus strains. However, the biological mechanism of this effect has not yet been properly elucidated. Therefore, this short communication focused on characterizing the in silico interactions of the PBP2a membrane receptor protein from S. aureus against the monomeric units of two polymeric materials previously used in the development of different nanoparticles loaded with ampicillin. Such polymers correspond to Eudragit E-100 chloride (EuCl) and the sodium salt of poly(maleic acid-alt-octadecene) (PAM-18Na). For this, molecular coupling studies were carried out in the active site of the PBP2a protein with the monomeric units of both polymers in neutral and ionized form, as well as with ampicillin antibiotic (model ß-lactam drug). The results showed that ampicillin, as well as the monomeric units of EuCl and PAM18Na, described a slight binding free energy to the PBPa2 protein. In addition, it was found that the amino acids of the active site of the PBPa2 protein have interactions of different types and intensities, suggesting, in turn, different forms of protein-substrate coupling.

Estafilococos oxacilino resistentes en queso blanco fabricado en el estado Anzoátegui, Venezuela / Oxacyllin resistant Staphylococcus in white cheese manufactured at the Anzoategui State, Venezuela

El objetivo de esta investigación fue detectar especies estafilocócicas oxacilino resistentes en quesos blanco duro y blando, fabricados artesanalmente en diversos municipios de la zona norte del estado Anzoátegui. Las cepas de Staphylococcus fueron aisladas e identificadas empleando métodos convencionales y se confirmaron las especies coagulasa negativas mediante galerías API 32 Staph (BioMérieux); la susceptibilidad a oxacilina y otros antibióticos por el método de difusión en disco y la presencia del gen mecA, por prueba de látex MRSA Slidex (BioMérieux) que pone de manifiesto la proteína PBP2a. De 130 quesos evaluados, se aislaron 171 cepas estafilocócicas, 26 (15,2%) resistentes a oxacilina (61,5% con presencia del gen), distribuidas como sigue: 14 cepas de S. epidermidis (8,2%), 6 de S. capitis (3,4%), 2 de S. aureus (1,2%), 2 de S. hominis (1,2%), 1 de S. warneri (0,6%) y 1 de S. saprophyticus (0,6%). La presencia del gen que codifica para la proteína PBP2a se detectó tanto en cepas con homorresistencia (76,9%) como con heterorresistencia (23,1%). S. haemolitycus fue 100% sensible a oxacilina. La presencia de cepas estafilocócicas oxacilino resistentes en el queso blanco, puede representar un riesgo para salud pública ya que podría servir como fuente de diseminación de éstas y acrecentar el problema de la resistencia.

The purpose of this study was to detect oxacyllin resistant Staphylococcus species in hard and soft white cheese manufactured by artisans at various municipalities of the northern area of Anzoátegui State. The Staphylococcus strains were isolated and identified using conventional methods and coagulase negative species were confirmed through API 32 Staph (BioMérieux) galleries; susceptibility to oxacyllin and other antibiotics was determined by the disk diffusion method and presence of the mecA gene with the MRSA Slidex (BioMérieux) latex test that identifies PBP2a protein. From 130 cheeses evaluated, we isolated 171 Staphylococcus strains, 26 of which (15,2%) were oxacyllin-resistant (61,5% with presence of the gene), distributed as follows: 14, S. epidermidis strains (8,2%); 6, S. capitis (3,4%); 2, S. aureus (1,2%); 2, S. hominis (1,2%); 1, S. warneri (0.6%); and 1, S. saprophyticus (0.6%). Presence of the protein PBP2a codifying gene was detected in both homoresistant (76.9%) and heteroresistant (23.1%) strains. S. haemolitycus was 100% oxacyllin sensitive. Presence of oxacyllin resistant strains in white cheese can represent a public health risk since it could serve as a dissemination source, increasing the resistance problem.