OBJECTIVE To investigate the prevalence of multidrug resistance(MDR) mechanisms of Staphylococcus haemolyticus against oxacillin,gentamycin and erythromycin.METHODS Agar dilution method was performed to detect the minimal inhibition concentration(MIC) of 3 antimicrobial agents against 63 strains of S.haemolyticus,and the resistance genes of mecA,aac(6′)+aph(2″),ermA,ermB,ermC and msrA/msrB were investigated by PCR in all clinical isolates.RESULTS mecA Gene was detected in 62 isolates of meticillin-resistant S.haemolyticus(MRSH),and aac(6′)+aph(2″) gene was found in 50 isolates resistant to gentamicin,and the most prevalence erythromycin resistance gene in S.haemolyticus was msrA/msrB(58.7%),followed by ermC(31.7%).Among the 43 MDR strains,the more commonly encountered three genes were mecA,aac(6′)+aph(2″) and msrA/msrB(58.1%)or ermC(20.9%),and 8 isolates(18.6%) were found harboring four genes of mecA,aac(6′)+aph(2″),ermC and msrA/msrB.CONCLUSIONS The mecA,aac(6′)+aph(2″),msrA/msrB and ermC genes are main resistance mechanisms against oxacillin,gentamicin and erythromycin in mutidrug resistant S.haemolyticus.

OBJECTIVE To investigate the susceptibilities of Staphylococcus aureus and Enterococcus isolated from Shenzhen Hospital during 2005 to 2006 to 17 antimicrobial agents.METHODS The minimal inhibitory concentrations(MICs) of 17 antibacterial agents were determined by agar dilution method,WHONET5.3 software was used to analyze the data.RESULTS The prevalence of meticillin-resistant S.aureus(MRSA) was 20.7%.Vancomycin and teicoplanin remained very high activity against MRSA(100%),with the MIC50 and MIC90 of 0.5 and 1 ?g/ml,respectively.Fluoroquinolones(ciprofloxacin,levofloxacin and gatifloxacin),trimethoprim/sulfamethoxazole,erythromycin,and clindamycin showed very low activity against MRSA(0-33.3%).The most active agent against Enterococcus faecalis was vancomycin and teicoplanin(100.0%),followed by piperacillin/tazobactam,imipenem and ampicillin(97.2-100.0%).E.faecium showed high resistance to various agents,except to vancomycin and teicoplanin(susceptible rate 100.0%).Cross-resistance to fluoroquinolones was found among MRSA,MSSA,E.faecalis,and E.faecium.CONCLUSIONS MRSA and E.faecium isolated from our hospital showed high resistance to multiple antimicrobial agents except vancomycin and teicoplanin.

OBJECTIVE To investigate the antimicrobial susceptibility of 9 antimicrobial agents and multidrug(resistance)(MDR) phenotype among Acinetobacter baumannii isolated from hospitalized patients.METHODS Disk diffusion method was used to detect the inhibitory zone diameter of 9(antimicrobial) agents to 221 strains of A.baumannii.according to standard from NCCLS in South China during 2002 to 2004.RESULTS 25.3% and 26.4% of isolates from ICU patients showed resistance to(imipemem) and meropemem,respectively,and the resistance rates were greater among the(isolates) from ICU(patients) than those from non-ICU inpatients by 13.4% and 12.2 %(P

Thiamin pyrophosphate (TPP) is a thiamine (vitamin B1) derivative and an essential cofactor in oxidative metabolism of the sugars,fatty acids and amino acids in living cells.By now,numerous TPP-dependent artificial riboswitch systems have been developed to regulate target gene expression but limited in bacteria,fungi or plant cells.Herein,the activating (switch-on) and inhibiting (switch-off) TPP-depended hammerhead ribozyme switches,which are from previous reported structures of prokaryotes screening,were investigated in mammalian cells.These ribozyme switches were inserted into the 3'UTR of the enhanced green fluorescence protein (EGFP) gene to construct the efficient ribozyme-based artificial switches through overlap extension PCR cloning.The HEK293 cells were transfected with the engineered ribozyme switches at increasing concentration of TPP.The EGFP gene-regulatory ability was analyzed with fluorescent microscope and flow cytometry.These TPP-inducible gene regulation devices showed the obvious ligand dose-dependency and excellent specificity.Two switch-on and one switch-off constructs demonstrated 3.1-fold or 1.9-fold increment and 2.3-fold reduction of EGFP level respectively with 150 μ mol/L TPP.The ligand-responsive ribozyme switches,by tuning the change of TPP concentration into the visual reporter genetic expression in cells,enable an efficient development of label-free,noninvasive and high-specific biosensors in living mammalian cells.