ABSTRACT
Objective To study the discrepancy influence of the sulbactam content on susceptibility testing results of cefoperazone/sulbactam combination disks.Methods Agar dilution method was used to determine MICs of cefoperazone,cefoperazone/sulbactam(2:1 and 1:1),and disk diffusion was used to detect the zone diameters of cefoperazone,cefoperazone/sulbactam(75/30 and 75/75μg/disk)disks against 534 clinical gram-negative isolates.The discrepancy within the results of MICs,zore diameters,the method of agar dilution and disk diffusion was analyzed.Results By standard agar dilution method,MIC_(50) of cefoperazone,cefoperazone/sulbactam(2:1 and 1:1)were 32,16,16μg/ml,and MIC_(90) of those were ≥256.128,64 μg/ml respectively.No statistic discrepancy was found for MICs between the ratios of 2:1 and 1:1 combination by Wilcoxon ranks test(Z=-0.248,P=0.804).Susceptibility rate,resistance rate,and intermediate rate with 75/30μg disk were 55.3%,24.5%and 20.2%respectively,which were similar to those determined by agar dilution method.Susceptibility rate,resistance rate,and intermediate rate(I%)with 75/75μg disk were 72.5%,12.4% and 15.1% respectively,compared with the susceptibility rate from 75/30μg disk was 17.2% higher.Statistic discrepancy were tested by paired t-test (t=21.613,P＜0.01)with two groups of whole strains' zone diameters from 75/30μg and 75/75μg disks,and resulting in the difference of susceptibility or resistance rates for ESBL-producing strains,Acinetobacter bauamnnii and Enterobacteriaceae without ESBL tested isolates.On the contrary,for Pseudomonas aeruginosa,Stenotrophomonas maltophilia and ESBL negative isolates,the zone diameters discrepancy was not statistically significant between the results from 75/30μg and 75/75μg disks.Conclusions There is no statistic discrepancy between the susceptibility results from cefoperazone/sulbactam(2:1 or 1:1 ratios)in dilution method and in diffusion method with 75/30μg disk.When the 75/75μg disk is used to be tested for ESBL-producing strains,Acinetobacter bauamnnii and other Enterobacteriaceae,the results should be shown with sulbactam content.
ABSTRACT
Objective To analyze the antibiotic resistance of clinical isolated bacteria in elderly inpatients in Beijing Hospital from 2006 to 2008.Methods A total of 5710 strains isolated from elderly inpatients received antibiotic sensitivity test (AST) by using K-B method, and the data were analyzed with WHONET 5.4 software.Results During the 3 years, in constituent ratio of bacteria, P.aeruginosa, E.coli and Stenotrophomonas maltophilia were at the top of gram-negative bacteria.And S.aureus, coagulase-negative Staphylococcus (CONS), S.pneumoniae and Enterococcus spp.were at the top of gram-positive bacteria.The results of AST in vitro showed that 19 of 121 strains of S.pneumoniae were penicillin-insensitive S.pneumoniae (PNSP).In 690 strains of S.aureus, the methicillin-resistant S.aureus (MRSA) ratio was 80.2%, and vancomycin-insensitive strains were not found.And 114 strains of Enterococeus faecalis and 95 strains of Enterococcus faecalis were isolated, while the antibiotic resistance of the latter was stronger than the former, and 19 strains were vancomycin-resistant strains.The detection ratios of E.colt producing ESBLs were 41.7%, 55.0% and 56.8%, and the detection ratios of Klebiella pneumonia producing ESBLs were 16.0%, 22.4% and 27.3 %.The antibiotic resistance of ESBL-producing bacteria was much stronger than non-ESBLs producing bacteria.Multi-antibiotic resistant strains of Pseudomonas aeruginosa and Acinetobacter spp.were found.Conclusions It is necessary to detect the drug-resistant strains periodically for understanding the changes in bacterial resistance and providing a theoretical basis for the medication by the clinical experience.
ABSTRACT
OBJECTIVE To determine the mutant prevention concentration(MPC) of 3 cephalosporins against clinical isolates of Staphylococcus aureus and Streptococcus pneumoniae.METHODS Agar dilution was used to determine the minimum inhibitory concentration(MICs) and MPCs of cefaclor,cefprozil and cefuroxime against S.aureus and the MICs to Str.pneumoniae.The MPCs against Str.pneumoniae were determined by mixing-bacterium.RESULTS The MPCs and the ratio of MPC90/MIC90 of cefaclor,cefprozil and cefuroxime against S.aureus were 32,16;16,16;2,8;and the MPCs and the ratio of MPC90/MIC90 against Str.pneumoniae were 8,16;4,32;2,8,respectively.CONCLUSIONS The ability of cefuroxime for restricting the selection of resistant mutant of Str.aureus and S.pneumoniae is stronger than cefaclor and cefprozil.
ABSTRACT
OBJECTIVE The in vitro activity of home-made rifamycin was investigated.METHODS Minimal inhibitory concentrations(MICs) were determined by agar dilution method using multipoint inoculator.RESULTS The results indicated that MIC50 and MIC90 of rifamycin against MRSA and MSSA were similar to vancomycin. The values were 1 and 2 mg／L, respectively. Rifamycin against MRSE was 4 times stronger than vancomycin.The value of MIC50 was 0.5 mg／L.The MIC50 of rifamycin against S.pneumoniae,Branhamella catarrhalis,and Listeria monocytogenes were 8,128 and 4 times lower than vancomycin, respectively.CONCLUSIONS There are good antibacterial activity of home-made rifamycin against meticillin resistant Staphyloccocus and the most species of clinical isolates,so can be used the infective diseases by MRSA and MRSE.
ABSTRACT
Objectives To evaluate mini/VITAL and BacT/Alert, two fully automated blood culture systems. Methods Standard mini/VITAL AER and ANA bottles (bioM′erieux, Marcy 1′Etoile, France) and BacT/Alert FAN aerobic and FAN anerobic bottles (organon Netherlands) were used. The bottles were analysed over a period of 7 days. A total of 600 samples of blood, 108 samples of body fluid, and 100 strains of imitation were detected by mini/VITAL and BacT/Alert parallelly. The bottles of flagged positive were smeared and Gram stained before being examined under a microscope. Subcultures were performed in parallel on fresh blood agar and chocolate agar incubated in microaerophilic Conditions with 5% CO 2. All the bottles flagged negative were examined in the same conditions as the positive bottles. Results mini/VITAL: The positive rate for aerobic and anaerobic blood cultures was 10% and 5% respectively, for aerobic body fluid culture was 26 9%. No contaminants were detected. 0.5% false positive and 0.8% false negative were detected. 90% of positive sample were detected in 48 h. The shortest time of report of positive bottles was 1.5 h for blood culture. BacT/Alert: The rate of positive of aerobic and anaerobic blood culture was 9.8% and 5% respectively. The positive rate of body fluid culturs was 26.9%. There were used 3 bottles contaminated. The false positive and false negative rate were 0.5% and 0 98% respective. 95.5% of positive bottles were detected in 48 h. The shortest time of flagged positive was 2.5 h. Conclusion mini/VITAL and BacT/Alert were accurate automated blood culture systems for the detection of bacteremia. There was no significant difference on the speed of detection between BacT/Alert FAN bottles and mini/VITAL standard bottles.