title: Antimicrobial activity of Manuka honey against antibiotic-resistant strains of the cell wall-free bacteria Ureaplasma parvum and Ureaplasma urealyticum.
abstract: The susceptibility of the cell wall-free bacterial pathogens Ureaplasma spp. to Manuka honey was examined. The minimum inhibitory concentration (MIC) of Manuka honey for four Ureaplasma urealyticum and four Ureaplasma parvum isolates was determined. Sensitivity to honey was also compared to clinical isolates with resistance to tetracycline, macrolide and fluoroquinolone antibiotics. Finally step-wise resistance training was utilized in an attempt to induce increased tolerance to honey. The MIC was dependent on the initial bacterial load with 7·5 and 18·0% w/v honey required to inhibit U. urealyticum at 1 and 106colour changing units (CCU), respectively, and 4·8 and 15·3% w/v required to inhibit U. parvum at 1 and 106CCU respectively. MIC values were consistently lower for U. parvum compared with U. urealyticum. Antimicrobial activity was seen against tetracycline-resistant, erythromycin-resistant and ciprofloxacin-resistant isolates at 105CCU. No resistance to honey was observed with 50 consecutive challenges at increasing concentrations of honey. This is the first report of the antimicrobial activity of Manuka honey against a cell wall-free bacterial pathogen. The antimicrobial activity was retained against antibiotic-resistant strains and it was not possible to generate resistant mutants.
  
  
  CONCLUSIONS
  Manuka honey is known to have a broad spectrum of antimicrobial activity, with the bacterial cell wall being suggested as a predominant site of action. This study has demonstrated that Manuka honey has activity against Ureaplasma spp., a genus of cell wall-free bacteria which are intrinsically resistant to many available antibiotics making treatment inherently difficult. This is the first report of the antimicrobial activity of Manuka honey against a bacterial pathogen, in the absence of a cell well and opens scope for the use of components of Manuka honey as a therapeutic among Ureaplasma infections.
authors.affiliation: Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK.
authors.forename: K L
authors.initials: KL
authors.lastname: Hillitt
authors.affiliation: Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK.
authors.forename: R E
authors.initials: RE
authors.lastname: Jenkins
authors.affiliation: School of Medicine, Cardiff University, University Hospital of Wales, Cardiff, UK.
authors.forename: O B
authors.initials: OB
authors.lastname: Spiller
authors.affiliation: Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK.
authors.forename: M L
authors.initials: ML
authors.lastname: Beeton
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002473:Cell Wall / Q000187:drug effects; D002939:Ciprofloxacin / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D006722:Honey / Q000032:analysis*; D008826:Microbial Sensitivity Tests; D013752:Tetracycline / Q000494:pharmacology; D014509:Ureaplasma / Q000187:drug effects* / Q000502:physiology; D016990:Ureaplasma urealyticum / Q000187:drug effects* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin; D004917:Erythromycin; D013752:Tetracycline
keywords: antimicrobials; infection; microbial physiology; microbial structure; resistance