[Analysis of epidemiological characteristics of bacillary dysentery with multiple-onset in Henan Province from 2005 to 2020].

Objective: To understand the epidemiological characteristics of bacillary dysentery with multiple-onset in Henan province from 2005 to 2020. Methods: The reported cases of bacillary dysentery (including confirmed cases and clinically diagnosed cases) in Henan Province from January 2005 to December 2020 were collected through China's National Disease Supervision Information Management System. The main information included gender, age, home address, date of onset and date of diagnosis. The interval between two episodes of the same case was more than 15 days, which was judged as two episodes. The incidence characteristics of bacillary dysentery patients with two or more cases in Henan Province from 2005 to 2020 were analyzed, and the regional distribution map of cases was drawn using ArcGIS software. Results: From 2005 to 2020, a total of 250 430 cases of bacillary dysentery were reported in Henan Province, with a cumulative incidence rate of 228.66/100 000. There were 2 342 cases with two or more attacks. The incidence of recurrent cases of bacillary dysentery increased year by year (χ2trend=2 932.28, P<0.001). There was no significant difference in the incidence of two or more cases of different sexes (χ2=0.39, P=0.540). There was significant difference in the incidence among different age groups (χ2=438.40, P<0.001). The incidence of two or more cases in the 60-69 age group was relatively high (1.70%). The shortest time interval between the onset of the disease was 16 days, and the longest was 5 579 days, with M (Q1, Q3) about 428 (237, 843) days. Compared with healthy people, those with a history of bacterial diseases had a higher risk of developing bacillary dysentery (RR: 4.12, 95%CI: 3.95‒4.29). Conclusion: The proportion of patients with multiple-onset shows an increasing trend, and there is an age difference.

[Analysis on prevalence and epidemic risk of animal plague in different ecological plague foci in Inner Mongolia Autonomous Region].

The risk of plague epidemics and relapse of various types of plague foci persists in Inner Mongolia Autonomous Region. For Marmota sibirica plague foci, the animal plague has not been found but antibody has been detected positive. Nowadays, Marmota sibirica has been increasing in population and distribution in China. In bordering countries Mongolia and Russia, the animal plague has been continuously prevalent. For Spermophilus dauricus plague foci, the animal plague has been taken place now and then. Compared to the above foci, the animal plague is most prevalent in Meriones unguiculatus plague foci and frequently spread to humans. Due to higher strain virulence and historical disaster in Marmota sibirica plague foci and Spermophilus dauricus plague foci, plague prevention and control should be strengthened on these foci. In addition to routine surveillance, epidemic dynamics need to be further monitored in these two foci, in order to prevent their relapse and spread to humans.

[Characteristics and diversity of infectious diarrheal caused by various pathogens].

Objective: To understand the characteristics and differences of diarrhea-related symptoms caused by different pathogens, and the clinical features of various pathogens causing diarrhea. Methods: Etiology surveillance program was conducted among 20 provinces of China from 2010 to 2016. The acute diarrhea outpatients were collected from clinics or hospitals. A questionnaire was used to survey demographics and clinical features. VFeces samples were taken for laboratory detection of 22 common diarrhea pathogens, to detect and analyze the clinical symptom pattern characteristics of the patient's. Results: A total of 38 950 outpatients were enrolled from 20 provinces of China. The positive rates of Rotavirus and Norovirus were the highest among the five diarrhea-causing viruses (Rotavirus: 18.29%, Norovirus: 13.06%). In the isolation and culture of 17 diarrhea-causing bacterial, Escherichia coli showed the highest positive rates (6.25%). The clinical features of bacterial diarrhea and viral diarrhea were mainly reflected in the results of fecal traits and routine examination, but pathogenic Vibrio infection was similar to viral diarrhea. Conclusion: Infectious diarrhea presents different characteristics due to various symptoms which can provide a basis for clinical diagnosis.

[Interpretation for diagnosis of Yersiniosis].

Yersiniosis is one of the "other infectious diarrhea" of the notifiable infectious diseases and also an important food-borne disease. However, it lacked the basis or standard for diagnosis. The Chinese Preventive Medicine Association coordinated experienced researchers from National Institute for Communicable Disease Control and Prevention, China CDC and other institutes to produce the group standard entitled "Diagnosis of Yersiniosis" (T/CPMA 005-2019). Based on the principle of "legality, scientificity, advancement, and feasibility" , the standard gives a clear definition for Yerisiniosis, stipulates diagnosis basis, principles and main differential diagnosis and provides two informative appendixes for epidemiological and clinical characteristics and a normative appendix for laboratory detection. The standard provides accurate basis and methods of Yersiniosis diagnosis for hospitals and CDCs at all levels in China. It will solve the problems that Yersiniosis cannot be clearly diagnosed for clinical cases and in the outbreaks.

[Etiological study of diarrhea in children under 5 years old in Dongcheng district of Beijing].

Objective: To analyze the etiological characteristics of infectious diarrhea among people under 5 years old in Dongcheng District, Beijing. Methods: The age, time of infection, clinical symptoms and laboratory test results of the cases who didn't used antibiotics within 3 days in the second maternal and child health care hospital were collected from 2012 to 2015, through the information management system of infectious disease monitoring technology platform. To compare the detection rate of virus and bacteria in children with different sex, time and age,and the difference of clinical characteristics between virus detection group and bacteria detection group by chi square test. Results: 1 977 cases of infectious diarrhea were collected, the median of the month age (P(25), P(75)) was 14.19 (8.31, 23.15) months. The virus detection rate was 34.3% (679 cases); the bacterial detection rate was 14.6% (288 cases). The difference of virus detection rate in children with different months was statistically significant (χ(2)=72.38, P<0.001), the virus detection rate of 24-60 months (40.9% (188/460)) was the hightest, and the detection rate of 0-5 months (15.3% (48/314)) was the lowest. The difference of bacteria detection rate was also statistically significant (χ(2)=32.67, P<0.001), and the detection rate of 12-17 months (19.0% (81/426)) was the highest, the detection rate of 0-5 months (6.7% (21/314)) was the lowest. The proportion of vomit and water sample in the virus detection group was 22.2% (136 cases) and 73.3% (449 cases), respectively, which were higher than those in bacteria detection group (8.1% (18 cases) and 57.2% (127 cases)), the difference was statistically significant (χ(2) values were 125.92 and 19.60; P values were both<0.001); the proportion of mucus stool and fever was 0.8% (5 cases) and 14.0% (86 cases), respectively, which were lower than those in bacterial detection group (4.1% (9 cases) and 18.5% (41 cases)), and the difference was statistically significant (χ(2) values were 8.50 and 23.01; P values were 0.004 and <0.001). Conclusion: The virus detection rate of infantile infective diarrhea is higher than that of bacteria in Dongcheng district of Beijing, and the clinical characteristics are significantly different.

[The effect of AmpD on the expression of AmpC ß-lactamase and the regulation mechanisms of ß-N-acetylglucosaminidase in Yersinia enterocolitica].

Objective: In this study, we analyze the regulation mechanisms of the expression of ampD in AmpC ß-lactamase and the regulation mechanism of ß-N-acetylglucosaminidase (NagZ) in Yersinia enterocolitica. Methods: We construct the mutation strains of Yersinia enterocolitica AmpD (AmpD1-3) gene (ampD1-3), Low-Molecular-Mass Penicillin-Binding Proteins (LMM PBPs) gene (pbp4, pbp5a, pbp5b, pbp7), NagZ gene (nagZ), and ampR gene by deleting and complementing genes, and induce them by cefoxitin. We determined the activity of AmpC ß-lactamase activity (U) of mutant strains (basal level and induce level) by using cephalothiophene hydrolysis method, the promoter activity of AmpC ß-lactamase ((relative light unit (RLU)) was detected by the luxCDABEreporter system, and the activity of ß-N-acetylglucosaminidase (nmol/L) was determined by by using 4-nitrophenyl N-acetyl-ß-D-glucosaminide as the chromogenic substrate. Results: AmpD1 (Basal level: (3.29±1.58) U; Induced level: (4.08±1.75) U) was the most potent one. The YEΔ5b, YEΔ4Δ5b, YEΔ5aΔ5b and YEΔ5bΔ7 of ampC promoter activity increase significantly, whichYEΔ4Δ5b is the highest one (Basal level: (106 903.16±61 910.61) RLU; Induced level: (205 427.45±45 352.17) RLU). The YEΔ4Δ5bΔ7 of ampC promoter activity is the highest among triple mutant strain (Basal level: (304 108.04±99 274.53) RLU; Induced level: (531 440.21±68 891.02) RLU). Quadruple deletion strain YEΔ4Δ5aΔ5bΔ7 have the highest ampC promoter activity (Basal level: (1 013 810.99±260 955.96) RLU; Induced level: (1 230 214.59±205 526.79) RLU). After the deletion of nagZ gene, there is no significant change in ß-lactamase activity of YEΔD1D2D3ΔZ, while ß-lactamase activity of YEΔ4Δ5aΔ5bΔ7ΔZ shows a significant decrease (Basal level: (0.30±0.20) U; Induced level: (0.29±0.21) U), which basically drops to the wild strain level. Conclusion: This is the first report of ampC multi-step upregulation mechanism driven by three AmpD homologues in Yersinia enterocolitica. The AmpC regulation mode with the function of single PBP4, PBP5a or PBP7 is relatively low, which work in coordination with PBP5b. Yersinia enterocolitica have both NagZ-depend and NagZ-independent mechanisms for ß-lactamase expression.

[Etiology of bacterial diarrhea in large cities, mid-sized/small cities and rural areas of China].

Objective: To understand the etiological characteristics of bacterial diarrhea in different areas, including large cities, mid-sized/small cities and rural area, in China. Methods: A cross-sectional surveillance was conducted in 17 provinces of China from 2010 to 2014. The acute diarrhea outpatients were selected from clinics or hospitals in large cities, mid-sized/small cities, including rural-urban fringe zones, and rural areas. The demographical and clinical characteristics of the patients were collected by using questionnaire, and stool samples were taken from them for laboratory detection of 17 kinds of bacteria. The differences in pathogen positive rates (PPR) and pathogen spectrum across the cases from three-type areas were compared. The different infection risk in different cases were analyzed with unconditional logistic regression model. Results: In our study, we enrolled 9 253 cases from large cities, 5 138 cases from rural areas and 13 683 cases from midsized/small cites. The pathogen with largest differences in infection rate across the three-type areas was Shigella (S.) flexneri (rural area: 5.81%, mid-sized/small city: 2.78%, large city: 0.46%), followed by Aeromonas (A.) hydrophila (rural area: 2.14%, mid-sized/small city: 0.96%, large city: 0.48%). Compared with cases in large cities, the cases in mid-sized/small cities and rural areas had higher infection risks for S. flexneri (mid-sized/small city: OR=6.481, 95%CI: 4.666-9.002, rural area: OR=11.304, 95%CI: 8.018-15.938) and A. hydrophila (mid-sized/small city: OR=1.992, 95%CI:1.401-2.832, rural area: OR=4.083, 95%CI: 2.833-5.884). The constituent ratio of diarrheagenic Escherichia coli and Salmonella increased with the urbanization development, while the ratios of Shigella and A. hydrophila had an opposite trend. S. sonnei (60.00%) was the predominant serogroup of Shigella in urban infections, while S. flexneri (77.37%) was the predominant serogroup in rural infections. Conclusion: The differences in pathogen spectrum of bacterial diarrhea were obvious across large cities, mid-sized/small cities and rural areas in China, especially the differences in the infection rates of S. flexneri and A. hydrophila.

[Epidemiological characteristics of diarrheagenic Escherichia coli among diarrhea outpatients in China, 2012-2015].

Objective: To understand the epidemiological characteristics of diarrheagenic Escherichia (E.) coli (DEC) among diarrhea outpatients in China. Methods: Diarrhea surveillance program was conducted in outpatient and emergency departments from 170 hospitals that under the sentinel programs in 27 provinces, from 2012-2015. Clinical and epidemiological data regarding diarrhea patients were collected, with fecal specimens sampled and tested for DEC in 92 network-connected laboratories. Results: Among all the 46 721 diarrhea cases, 7.7% of them appeared DEC positive in those with geographic heterogeneity. In 2 982 cases (6.4%) with available data on PCR subtypes of DEC, enteroaggregative E. coli (EAEC, 1 205 cases, 40.4%) appeared the most commonly seen pathogens, followed by enteropathogenic E. coli (EPEC, 815 cases, 27.3%), and enterotoxigenic E.coli (ETEC, 653 cases, 21.9%). The highest positive rate of DEC was observed in outpatients of 25-34 years old (10.1%), living in the warm temperate zones (11.1%), and with mucous-like stool (9.4%). The positive rate of DEC showed a strong seasonal pattern, with peaks in summer, for all the subtypes. Conclusions: DEC seemed easy to be detected among diarrhea outpatients in China, with EAEC, EPEC and ETEC the most commonly identified subtypes. Epidemiological characteristics regarding the heterogeneities of DEC appeared different, in regions, age groups and seasons. Long-term surveillance programs should be strengthened to better understand the epidemiology of DEC, in China.

Autopsy report of four cases who died from Streptococcus suis infection, with a review of the literature.

There was an outbreak of human Streptococcus suis (S. suis) infection in southwest China in 2005. The total number of documented patients was 204 and 38 of them died. Four cases were autopsied and are reported in this paper. The autopsies showed that multiple organs were involved, with a prominent injury of the lung, kidney, and intestine. The essential pathologic changes were multiple microthrombi (hyaline thrombi) formation in the capillaries of various organs and tissues, accompanied by congestion and hemorrhage. The pathogen of the disease was S. suis, serotype 2, which was confirmed by means of germ culture of the heart, blood, and tissue samples at the Chinese Center for Disease Control and Prevention (China CDC). The autopsy diagnosis of all four cases was septicemia with disseminated intravascular coagulation (DIC). The cause of death was toxic shock with multi-organ dysfunction. Combined with the epidemic features, clinical manifestations, etiological, and autopsy findings, it accorded with streptococcal toxic shock syndrome (STSS).