ABSTRACT
The toxin-producing bacterium Vibrio cholerae can cause severe diarrhea and has caused seven global pandemics. Traditional viable cell counts and phage plaques are commonly used to evaluate the efficacy of virulent phage clearance of V. cholerae, but these operations are time-consuming and labor-intensive, and difficult to provide real-time changes. It is desirable to develop a simple and real-time method to monitor V. cholerae during phage lysis. In this study, a luminescence-generating plasmid pBBR-pmdh-luxCDABE was transformed into three O1 serogroup drug-resistant strains of V. cholerae. The results showed that the luminescence value as a monitoring index correlates well with the traditional viable cell count method. Monitoring the number of live cells of V. cholerae by measuring the luminescence allowed real-time analysis of the number of bacteria remaining during phage lysis. This method enables repeated, interference-free, continuous multiple-time-point detection of the same sample without the time delay of re-culture or plaque formation, facilitating real-time monitoring and analysis of the interaction between the phage and the host bacteria.
Subject(s)
Bacteriophages/genetics , Luminescence , Plasmids , Vibrio choleraeABSTRACT
Objective To understand the epidemiological and molecular characteristics of typhoid and paratyphoid in China from 2009 to 2013,and provide evidence for the prevention and control of typhoid and paratyphoid,the development and improvement of surveillance strategies.Methods Epidemiological analysis was conducted on the incidence data of typhoid and paratyphoid,and related public health emergencies in China during 2009-2013.Pathogen isolation and culture,serologic test were conducted for the typhoid and paratyphoid cases from 13 national surveillance sites.The isolates were subjected to antimicrobial susceptibility testing.Pulsed-field gel electrophoresis (PFGE) was performed for the molecular typing of these isolates.Results The average incidence of typhoid and paratyphoid in China during this period was 1.03/100 000.The reported case number and incidence decreased with year.The provinces reporting high case numbers were Yunnan,Guizhou,Guangxi,Hunan,Zhejiang,Guangdong and Xinjiang.The incidence of age group 0-4 years was highest.The proportion of farmers and children outside child care settings showed an increasing tendency over time.The annual incidence peak was during July-August.Twenty five outbreaks occurred during 2009-2013.The results of pathogen isolation and culture showed that the positive rate was 3.00％ (940/31 322),among the positive isolates,the proportion of Salmonella paratyphi A accounted for higher proportion (68.19％,641/940) compared with Salmonella typhi (31.60％,297/940).The drug resistances of Salmonella typhi and Salmonella paratyphi varied,but their resistances to nalidixic acid were highest (50.22％ and 85.33％) respectively.A certain amount of Salmonella typhi isolates showed the resistance to the 3rd generation cephalosporins.PFGE analysis showed divergent patterns of Salmonella typhi compared with limited patterns of Salmonella paratyphi A.Conclusion The epidemic level of typhoid and paratyphoid in China was relatively low,but the outbreak occurred occasionally.It is necessary to enhance the laboratory-based surveillance,particularly the capability of etiological diagnosis,outbreak investigation,response and antibiotic resistance monitoring,and conduct risk factor investigation in provinces with high incidences in recent years.
ABSTRACT
Objective To understand the epidemiological and molecular characteristics of typhoid and paratyphoid in China from 2009 to 2013,and provide evidence for the prevention and control of typhoid and paratyphoid,the development and improvement of surveillance strategies.Methods Epidemiological analysis was conducted on the incidence data of typhoid and paratyphoid,and related public health emergencies in China during 2009-2013.Pathogen isolation and culture,serologic test were conducted for the typhoid and paratyphoid cases from 13 national surveillance sites.The isolates were subjected to antimicrobial susceptibility testing.Pulsed-field gel electrophoresis (PFGE) was performed for the molecular typing of these isolates.Results The average incidence of typhoid and paratyphoid in China during this period was 1.03/100 000.The reported case number and incidence decreased with year.The provinces reporting high case numbers were Yunnan,Guizhou,Guangxi,Hunan,Zhejiang,Guangdong and Xinjiang.The incidence of age group 0-4 years was highest.The proportion of farmers and children outside child care settings showed an increasing tendency over time.The annual incidence peak was during July-August.Twenty five outbreaks occurred during 2009-2013.The results of pathogen isolation and culture showed that the positive rate was 3.00％ (940/31 322),among the positive isolates,the proportion of Salmonella paratyphi A accounted for higher proportion (68.19％,641/940) compared with Salmonella typhi (31.60％,297/940).The drug resistances of Salmonella typhi and Salmonella paratyphi varied,but their resistances to nalidixic acid were highest (50.22％ and 85.33％) respectively.A certain amount of Salmonella typhi isolates showed the resistance to the 3rd generation cephalosporins.PFGE analysis showed divergent patterns of Salmonella typhi compared with limited patterns of Salmonella paratyphi A.Conclusion The epidemic level of typhoid and paratyphoid in China was relatively low,but the outbreak occurred occasionally.It is necessary to enhance the laboratory-based surveillance,particularly the capability of etiological diagnosis,outbreak investigation,response and antibiotic resistance monitoring,and conduct risk factor investigation in provinces with high incidences in recent years.