Preliminary study on antibacterial activity of artemisinin and its derivatives / 中国中药杂志

In this study,in order to detect the antimicrobial activity of artemisinin and its derivatives artesunate and dihydroartemisinin,two methods including broth dilution and plate punching method were used to detect the antibacterial activity against gram-negative bacteria(Escherichia coli)and gram-positive bacteria(Staphylococcus aureus)of artemisinin,dihydroartemisinin and artesunate at various concentrations within 5 mmol·L~(-1)and at four time points(8,16,24,32 h).Two antibacterial positive drugs,streptomycin against E.coli and penicillin against S.aureus,were used as positive controls.Plate punching method showed that,unlike the results of 5 mmol·L~(-1)dihydroartemisinin or artesunate,no inhibition zone was detected at the same concentration of artemisinin after 24 h-treatment against E.coli.Broth dilution method showed that,the antibacterial activity of dihydroartemisinin against E.coli.was stronger than those of both artesunate and artemisinin;IC_(50)at24 h-treatment was 155.9μmol·L~(-1)for dihydroartemisinin,370.0μmol·L~(-1)for artesunate and none for artemisinin.Interestingly,dihydroartemisinin and artesunate showed the strongest antibacterial activity between 16-24 h,while artemisinin showed relatively stronger antibacterial activity between 8-16 h.Dihydroartermisinin showed no antibacterial activity against S.aureus.Above all,the antibacterial activity of artemisinins against E.coli is dihydroartemisinin>artesunate>artemisinin.Artemisinin and its derivatives have showed different antibacterial kinetics,and no antibacterial activity against S.aureus.has been detected with dihydroartemisinin.

Patronage and perceived efficacy of herbal antityphoid preparations, and anti-salmonella activity of a herbal preparation used in Ghana.

Objectives: To assess the patronage, and the perceived efficacy of herbal preparations in the treatment of typhoid fever, and to ascertain the anti-salmonella activity of a herbal preparation used as an antityphoid in Ghana. Materials and Methods: Purposively and conveniently from 700, 65 individuals who had had typhoid fever (clinically confirmed) were sampled. Well-structured questionnaires on the subject were administered to sampled individuals. Experimentally, the Minimum Inhibitory Concentration (MIC) of a herbal antityphoid preparation on Salmonella typhi was determined using the broth dilution method. Results: 46/65 (70.8%) used herbal preparations (19 used pre-packaged products; 27 used extemporaneous preparations) while 19/65 (29.2%) used orthodox drugs to treat their infection. Some of the herbs commonly used were Nauclea latifolia, Morinda lucida, Paullinia pinnata, Vernonia amygdalina, Cassia alata, Phyllantus fraternus, Azadirachta indica, Mangifera indica, and Carica papaya. Majority, 42/45 (91.3%), recovered after the use of the herbal anti-typhoid products (laboratory confirmation), 7/42 (15.2%) had relapse within three months, 9/45 (19.6%) experienced mild side effects. Experimentally, both the prepared herbal mixture and ciprofloxacin had MICs of 4 and 2 μg/μl respectively. Conclusion: Herbal anti-typhoid preparations are highly patronized and have been found to be efficacious. Experimentally the herbal mixture prepared showed interesting anti-salmonella activity.

Evaluation of the capability of four tests for identification of the in vitro susceptibility of tigecycline against Acinetobacter and Enterobacteriaceae isolates / 中华微生物学和免疫学杂志

Objective To evaluate the capability of four tests for identification of the in vitro suscepti-bility of tigecycline against Acinetobacter and Enterobacteriaceae isolates.Methods Disk diffusion test was per-formed to detect the sensitivity of 158 Acinetobacter and 339 Enterobacteriaceae isolates to tigecycline.The mini-mum inhibitory concentrations ( MICs) of tigecycline for non-sensitive isolates were detected by using broth dilu-tion method ( BDM) , MIC Test Strip ( MTS) and agar dilution method.The differences with antimicrobial sus-ceptibility among the four different methods were evaluated.Results Tigecycline showed good antibacterial ac-tivity against both non-sensitive Acinetobacter and Enterobacteriaceae isolates with most of the MIC50 values in the sensitivity range of (0.5-2) mg/L and all of the MIC90 values of 4 mg/L.The MIC50 and MIC90 values measured by BDM were respectively 1 mg/L and 4 mg/L.The sensitivity rates presented by the results of BDM were re-spectively 87.1%and 70.2%based on the standards made by Food and Drug Administration (FDA) and Euro-pean Committee on Antimicrobial Susceptibility Testing ( EUCAST) .Agar dilution method indicated that most of the MICs of tigecycline to Acinetobacter and Enterobacteriaceae isolates were two dilutions higher than those de-tected by BDM with essential agreement (EA) rate of 56.5%.Both the very major error (VME) and the major error (ME) values were 0 and the categorical agreement (CA) rate was 46.8%according to the FDA standard.The VME and CA values were 0.8% and 24.2% based on EUCAST standard.Compared with agar dilution method, MTS showed better results in determining the susceptibility of Acinetobacter and Enterobacteriaceae iso-lates to tigecycline with MIC50 and MIC90 values of 1.5 mg/L and 4 mg/L, which was similar to the capability of BDM.Referring to the FDA and EUCAST standards, the sensitivity rates were 83.1% and 21.0%, the CA rates was 81.5%and 29.8%, and the EA rate was 71.8%.Most of the results tested by MTS were one dilution higher than those by BDM.FDA standard showed better correlation than EUCAST standard.Disk diffusion method showed the ME, mE, VME and CA values were respectively 19.4%, 71.8%, 0 and 8.9%according to FDA standard.Conclusion Disk diffusion method, MTS and agar dilution method all showed differences with BDM in susceptibility testing.The capability of MTS was similar to that of BDM.The results evaluated by FDA standard were better than those by EUCAST standard.The in vitro susceptibility of bacteria to tigecycline could be tested by disk diffusion method using FDA standard for evaluation, and confirmed with MTS if isolates were resistance or intermediate strains.The BDM could be performed for further confirmation if necessary.

Evaluation of VITEK-2 System for Antibiotic Susceptibility Test of Streptococcus pneumoniae / 대한임상병리학회지

BACKGROUND: The rapid emergence of multi-drug resistant pneumococcal strains has heightened the importance of reliable and convenient susceptibility testing methods. The newly-developed VITEK-2 (bioMerieux, Inc., Hazelwood, MO, USA) System includes the capability of performing rapid susceptibility testing of Streptococcus pneumoniae using specially configured cards. The objective of this study is to evaluate the performance of the VITEK-2 System for susceptibility testing of S. pneumoniae. METHODS: One hundred clinical strains of S. pneumoniae (18 penicillin susceptible strains, 32 intermediate strains, and 50 resistant strains) were tested, which had been isolated in Samsung Medical Center. Minimum inhibitory concentrations (MICs) for penicillin, cefotaxime, erythromycin, ofloxacin, chloramphenicol, tetracyclin, and vancomycin were determined by broth dilution method and VITEK-2 System using AST-P506 cards. The results obtained by VITEK-2 System were compared to those obtained by broth dilution method. RESULTS: Overall agreement of MICs determined by two methods was 93.0% within the range of one dilution. The best agreement was achieved with vancomycin (100%), and in descending order, 99% with ofloxacin, 97% with erythromycin, 94% with chloramphenicol, 89% with cefotaxime, 88% with tetracycline, and 85% with penicillin. There were 1.9% of very major error, 2.0% of major error, and 8.6% of minor error. The mean time for generation of susceptibility results was 9.6 hours. CONCLUSIONS: VITEK-2 System provided rapid and reliable determinations of susceptibility category for most antibiotics and would be helpful as a substitution of existing MIC methods.