ABSTRACT
Objective To study the biological characteristics of, antibiotic resistance in and ger-micidal efficacy at different temperatures against Vibrio parahaemolyticus ( V. parahaemolyticus) strains isola-ted from different sources in order to provide reference for clinical treatment and prevention. Methods Stool samples from patients with diarrhea and small seafood product specimens from markets were collected and an-alyzed with biochemical identification method, serotyping analysis, drug susceptibility test and germicidal ef-ficacy test at different temperatures. Results There were 107 V. parahaemolyticus strains isolated from 1166 stool samples of patients with foodborne diarrhea with a positive rate of 9. 18％ and 42 from 72 seafood product samples with a positive rate of 58. 30％. V. parahaemolyticus strains isolated from the foodborne diar-rhea cases were divided into eight serogroups and among them, O3 and O4 were the predominant serogroups, accounting for 49. 53％ and 34. 58％, respectively. Most of the O antigens in small seafood products be-longed to serogroups of O4, O1 and O3, and four strains of O3 : K6 were isolated. Results of the drug sus-ceptibility test showed that both of the clinical isolates and marine product isolates were highly resistant to ampicillin and the drug resistance rates were 94. 39％ and 88. 10％, respectively. Antibiotic-sensitive strains to monocyclicβ-lactams, aminoglycosides, quinolones, carbapenems, tetracyclines and sulfonamides accounted for over 90. 00％ or even nearly 100. 00％. There were 17 (15. 89％) clinical strains and three (7. 14％) marine product isolates resistant to three or more kinds of antibiotics. At 80℃, the bactericidal rate for marine product isolates was 85. 71％ in 60 s and reached 100. 00％ in 90 s. At 90℃ and 100℃, these isolates could be completely killed in 40 s and 30 s. It took 120 s, 90 s and 50 s to kill clinical isolates at 80℃, 90℃ and 100℃, respectively. Conclusions This study systematically analyzed and compared the drug-resistant phenotypes of and the bactericidal efficacy at different temperatures on V. parahaemolyticus strains isolated from clinical samples and marine products. It would provide reference for preventing and con-trolling the spread of V. parahaemolyticus and hospital infection and for studying treatment strategies.
ABSTRACT
OBJECTIVE To study the germicidal efficacy and germicidal mechanism of compound ortho-phthalaldehyde(OPA) against Bacillus subtilis var.niger spores.METHODS Suspension quantitative germicidal test was used to observe the germicidal efficacy of compound OPA against B.subtilis var.niger spores.The germicidal mechanism of compound OPA was studied in transudation of protein and DNA and ultra-microstructure.RESULTS The results showed that at(20?1)℃,the logarithm mean reduction was greater than 5.00,after B.subtilis var.niger spores had been exposed to compound OPA for 30min.Some protein leaked from B.subtilis var.niger spores treated with compound OPA for some time,but there wasn′t DNA.The ultrastructure showed that the shape was amorphic,the electronic density of the coat was unequal,the core leaned to one side or appeared the transmission area.CONCLUSIONS Compound OPA can effectively kill B.subtilis var.niger spores.Its mechanisms are that in accordance with benzolkonium bromide(Bromogeramine) the compound OPA can change the osmotic pressure of cell and increase cell permeability,then it can easily penetrate to their target sites within the cell.
ABSTRACT
OBJECTIVE To evaluate the germicidal efficacy of phthalaldehyde disinfectant.METHODS Suspension quantitative bactericidal test was used to observe its bactericidal efficacy and stability.RESULTS The temperature was 20-21℃.The results showed that the average killing rates of Escherichia coli,Staphylococcus aureus and Candida albicans exposed to the solution containing 5 664mg/L phthalaldehyde for 1 min were 99.99%,and the(average) killing rates of spores of Bacillus subtilis var.niger exposed to the solution containing 5 664mg/L(phthalaldehyde) for 60 min and 90 min was 99.94% and 100%,respectively.When its stock solution was stored at 56℃ under airtight condition for 2 weeks,the content of phthalaldehyde decreased by 3.27%.CONCLUSIONS The phthalaldehyde disinfectant is a good and stable bactericide.