[Show abstract][Hide abstract]ABSTRACT: The anti-infectious activity of synbiotics against methicillin-resistant Staphylococcus aureus (MRSA) infection was evaluated using a novel lethal mouse model. Groups of 12 mice treated with multiple antibiotics were infected orally with a clinical isolate of MRSA at an inoculum of 10(8) CFU on day 7 after starting the antibiotics. A dose of 400 mg/kg 5-fluorouracil (5-FU) was injected intraperitoneally on day 7 after the infection. A dose of 10(8) CFU Bifidobacterium breve strain Yakult and 10 mg of galactooligosaccharides (GOS) were given orally to mice daily with the antibiotic treatment until day 28. The intestinal population levels of MRSA in the mice on multiple antibiotics were maintained stably at 10(8) CFU/g of intestinal contents after oral MRSA infection and the subsequent 5-FU treatment killed all the mice in the group within 14 days. B. breve administration saved most of the mice, but the synbiotic treatment saved all of the mice from lethal MRSA infection. The synbiotic treatment was effective for the treatment of intestinal infection caused by four MRSA strains with different toxin productions. There was a large difference among the six Bifidobacteria strains that were naturally resistant to the antibacterial drugs used. B. breve in combination with GOS is demonstrated to have valuable preventive and curative effects against even fatal MRSA infections.
[Show abstract][Hide abstract]ABSTRACT: To evaluate a new quantitative reverse transcription-PCR (qRT-PCR) assay for the rapid detection of methicillin-resistant Staphylococcus aureus (MRSA).
Primers for Staphylococcus-specific regions of 16S rRNA gene, spa gene and mecA gene were newly designed. RNAs extracted from broth-cultured strains were tested by qRT-PCR targeting each primer, and the bacterial counts obtained correlated well with those counted by the plating method with detection limits of 10(0), 10(1) and 10(2) CFU. The qRT-PCR assay targeting the 16S rRNA was 6430-fold or more sensitive than qPCR assay. All Staph. aureus strains tested were detected and none of the other Staphylococcus species and genus strains tested cross-reacted with the assay targeting the spa gene. All MRSAs tested were detected by the assay targeting the mecA gene. Clinical samples, faecal material and bronchial washout solutions were tested by our assay, and MRSAs were detected with a high sensitivity within 6 h.
Our qRT-PCR assay targeting three new primers to the target genes is a rapid and sensitive tool for the detection of MRSA directly from clinical samples.
Because of its sensitivity and rapidity, our qRT-PCR assay is considered to be a valuable tool for clinical management.
Article · Aug 2009 · Journal of Applied Microbiology