Minimum inhibitory concentrations of herbal essential oils and monolaurin for gram-positive and gram-negative bacteria

Abstract

New, safe antimicrobial agents are needed to prevent and overcome severe bacterial, viral, and fungal infections. Based on our previous experience and that of others, we postulated that herbal essential oils, such as those of origanum, and monolaurin offer such possibilities. We examined in vitro the cidal and/or static effects of oil of origanum, several other essential oils, and monolaurin on Staphylococcus aureus, Bacillus anthracis Sterne, Escherichia coli, Klebsiella pneumoniae, Helicobacter pylori, and Mycobacterium terrae. Origanum proved cidal to all tested organisms with the exception of B. anthracis Sterne in which it was static. Monolaurin was cidal to S. aureus and M. terrae but not to E. coli and K. pneumoniae. Unlike the other two gram-negative organisms, H. pylori were extremely sensitive to monolaurin. Similar to origanum, monolaurin was static to B. anthracis Sterne. Because of their longstanding safety record, origanum and/or monolaurin, alone or combined with antibiotics, might prove useful in the prevention and treatment of severe bacterial infections, especially those that are difficult to treat and/or are antibiotic resistant.

Comparison of antibacterial effect of seven 1-monoglycerides on food-borne pathogens or spoilage bacteria

“…The inhibitory concentrations of MAG-C12:0 of B. cereus or B. anthracis are within the range of 25-70 mg·l -1 (Lee et al 2002;Preuss et al 2005). Our results also correspond to these values.…”

“…aureus CCM 3953, the inhibition of which was caused by this MAG at a concentration of 250 mg·l -1 . This minimum inhibitory concentration is higher than the one detected in other strains of staphylococci (Lee et al 2002;Růžička et al 2003;Preuss et al 2005).…”

“…Růžička et al (2003) did not detect an inhibitory effect of MAG-C12:0 on E. coli or Klebsiella pneumoniae. No inhibitory effect of the same MAG against Salmonella, Escherichia and Klebsiella was observed (McLay et al 2002;Marounek et al 2003;Preuss et al 2005;Skrivanova et al 2006). It was possible to enhance the antimicrobial effect of 1-monoglycerides on enterobacteria by other factors, e.g.…”

Atividade antimicrobiana do óleo essencial de rizomas de açafrão (Curcuma longa L.) e gengibre (Zingiber officinale Roscoe) frente a salmonelas entéricas isoladas de frango resfriado

“…Sendo a Salmonella uma bactéria Gram-negativa, apresenta maior resistência do que outras espécies Gram-positivas (Preuss, 2005), podendo ser justificada pela dupla camada fosfolipídica, que protege a célula bacteriana de determinadas classes de compostos presentes nos óleos essenciais (Oussalah, 2007).…”

“…Estudos demonstram que o óleo essencial de Curcuma longa L. apresenta poder antimicrobiano em potencial contra diferentes patógenos alimentares incluindo diferentes sorovares de Salmonella (Franco et al, 2007;Péret-Almeida et al, 2008;Rattanachaikunsopon & Phumkhachorn, 2010).…”