Action of antibiotic oxacillin on in vitro growth of methicillin-resistant Staphylococcus aureus (MRSA) previously treated with homeopathic medicines.

BACKGROUND: Resistance to antibiotics is a major public health concern worldwide. New treatment options are needed and homeopathy is one such option. We sought to assess the effect of the homeopathic medicine Belladonna (Bell) and a nosode (biotherapy) prepared from a multi-drug resistant bacterial species, methicillin-resistant Staphylococcus aureus (MRSA), on the same bacterium. METHODS: Bell and MRSA nosode were prepared in 6cH and 30cH potencies in 30% alcohol and sterile water, according to the Brazilian Homeopathic Pharmacopeia and tested on MRSA National Collection of Type Cultures (NCTC) 10442. We assessed in vitro bacterial growth, deoxyribonuclease (DNAase) and hemolysin activity, and in vitro bacterial growth in combination with oxacillin (minimum inhibitory concentration - MIC). All values were compared to control: 30% alcohol and water. RESULTS: In vitro growth of MRSA was statistically significantly inhibited in the presence of Bell and nosode 6cH and 30cH compared to controls (p < 0.0001); and with combination of Bell or nosode 6cH and 30cH and oxacillin (p < 0.001). Bell 30cH and nosode 6cH and 30cH significantly decreased bacterial DNAse production (p < 0.001) and reduced red blood cell lysis. CONCLUSIONS: Cultures of MRSA treated with Belladonna or MRSA nosode exhibited reduced growth in vitro, reduced enzymatic activity and became more vulnerable to the action of the antibiotic oxacillin. Further studies are needed on the biomolecular basis of these effects.

Novel strategy for biofilm inhibition by using small molecules targeting molecular chaperone DnaK.

Biofilms are complex communities of microorganisms that attach to surfaces and are embedded in a self-produced extracellular matrix. Since these cells acquire increased tolerance against antimicrobial agents and host immune systems, biofilm-associated infectious diseases tend to become chronic. We show here that the molecular chaperone DnaK is important for biofilm formation and that chemical inhibition of DnaK cellular functions is effective in preventing biofilm development. Genetic, microbial, and microscopic analyses revealed that deletion of the dnaK gene markedly reduced the production of the extracellular functional amyloid curli, which contributes to the robustness of Escherichia coli biofilms. We tested the ability of DnaK inhibitors myricetin (Myr), telmisartan, pancuronium bromide, and zafirlukast to prevent biofilm formation of E. coli. Only Myr, a flavonol widely distributed in plants, inhibited biofilm formation in a concentration-dependent manner (50% inhibitory concentration [IC50] = 46.2 µM); however, it did not affect growth. Transmission electron microscopy demonstrated that Myr inhibited the production of curli. Phenotypic analyses of thermosensitivity, cell division, intracellular level of RNA polymerase sigma factor RpoH, and vulnerability to vancomycin revealed that Myr altered the phenotype of E. coli wild-type cells to make them resemble those of the isogenic dnaK deletion mutant, indicating that Myr inhibits cellular functions of DnaK. These findings provide insights into the significance of DnaK in curli-dependent biofilm formation and indicate that DnaK is an ideal target for antibiofilm drugs.

Agents for the decolonization of methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) bacteria are a common cause of hospital- and community-acquired infections. Persons may have asymptomatic colonization with MRSA in the nares, axillae, perineum, or groin. Since MRSA colonization often precedes infection, and infection is associated with significant morbidity and mortality, there is great interest in preventing the transmission of MRSA and decolonizing persons who harbor these bacteria. We provide an evidence-based review of MRSA decolonization agents. Our search strategy included the databases of the Cochrane Central Register of Controlled Trials, MEDLINE (1962-May 2008), and EMBASE (1980-May 2008). To identify unpublished trials, abstract books from appropriate major scientific meetings were hand searched, manufacturers were contacted, and pharmacology references were researched for available commercial products, formulations, adverse events, and dosing. The most extensive research in MRSA decolonization has been conducted with mupirocin, which is applied to the anterior nares 2-3 times/day for 5 days. Increased use is correlated to resistance development; therefore, routine decolonization is not prudent unless MRSA colonization is confirmed in the nares or other site. Retapamulin is under investigation for use in nares decolonization. If total body decolonization is necessary, bathing or showering with an antiseptic agent such as chlorhexidine gluconate is recommended in combination with mupirocin applied to the nares to improve the likelihood of eradication. Oral antibiotics have been evaluated for use in decolonization of the skin and nares but should be considered only in conjunction with topical agents and when all other decolonization attempts and environmental controls have been exhausted. Homeopathic and investigational agents may also be effective. Although mupirocin is the standard of care for decolonization of MRSA, several agents demonstrate efficacy and many merit further investigation.