BACKGROUND:Previous studies discovered that pRST98, original y isolated from Salmonel a enterica serovar typhimurium (S.typhimurium) could promote bacterial biofilm formation. In addition, bacterial harboring pRST98 can promote the secretion and expression of interleukin-10 after infection in cells and animals.
OBJECTIVE:In vitro studies have discovered the effects of interleukin-10 at varying concentrations and conjugative plasmid pRST98 on the biofilm formation of S.typhimurium.
METHODS:S.typhimurium wild-type strainχ3306, virulence plasmid-deletion S.typhimurium strainχ3337 and pRST98-transconjugant S.typhimuriumχ3337/pRST98 were established in vitro and cultured for biofilm formation. 1, 10, 100 μg/L interleukin-10 were added during the biofilm formation. 0 μg/L interleukin-10 was set as a control. Crystal violet staining method, semi-quantitative method, confocal laser scanning microscopy and scanning electron microscopy were used to determine the effects of interleukin-10 on the biofilm formation and compare the effects of S.typhimurium with or without pRST98.
RESULTS AND CONCLUSION:Intra-group comparison showed that, compared with the control group, S.typhimurium gathered together and formed thicker biofilm in concentration of 1 and 10 μg/L of interleukin-10. The promotion effects of S.typhimurium on biofilm formation were greatly improved in 10 μg/L. Interleukin-10 in 100 μg/L inhibited S.typhimurium biofilm formation. Inter-group comparison showed that, A570 inχ3337/pRST98 was greatly higher than that inχ3306 andχ3337 under the same concentration of interleukin-10. The results indicate that both 1 and 10 μg/L of interleukin-10 promote biofilm formation, especial y bacteria harboring pRST98.

Objective : To analyze the epidemiological characteristics of food-borne diseases in Jinshan District, Shanghai from 2014 to 2020, so as to provide the evidence for formulating the public health strategy for food-borne diseases control. Methods : The medical records of patients with food-borne diseases were collected from 16 monitoring hospitals in Jinshan District from 2014 to 2020, and the basic information, clinical symptoms, history of suspicious dietary exposure and disease diagnosis were extracted. The crowd distribution, temporal distribution, spatial distribution, history of suspected dietary exposure and etiological characteristics of patients with food-borne diseases were descriptively analyzed. Results : A total of 1 060 cases with food-borne diseases were reported in Jinshan District from 2014 to 2020, including 1 057 cases with infectious diseases ( 99.72% ) and 3 poisoning cases ( 0.28% ). The male/female ratio of the cases was 0.94∶1, and 47.55% ( 504 cases ) were at ages of 15 to 44 years. Working ( 402 cases, 37.92% ) and farming ( 218 cases, 20.57% ) were predominant occupations, and the detection of food-borne diseases was concentrated between May and October, with two peaks seen in August and May. The suspicious food exposure was predominantly meat and meat products (215 cases, 20.28%), and the suspicious food exposure place was predominantly at home ( 363 cases, 34.25% ). In addition, the positive rate of food-borne infection was 23.03% in 712 samples, including 123 samples with Vibrio parahaemolyticus infections ( 17.83% positive rate ), and 26 samples with Salmonella infections ( 3.65% positive rate ). Conclusion Food-borne diseases were highly prevalent in summer in Jinshan District from 2014 to 2020, and infectious cases were predominant. Young people, workers and farmers are at high risk of food-borne diseases, and Vibrio parahaemolyticus and Salmonella were predominant pathogens.

ObjectiveTo understand the current drug resistance status and bacterial multilocus sequence typing （MLST） of human and avian Campylobacter jejuni in Jinshan District， Shanghai. MethodsFecal samples were collected from diarrhea patients in the annuity mountainous area from 2021 to 2022， and poultry and related samples were collected from 2 poultry farms in the Jinshan area for detection of C. jejuni. Minimal inhibitory concentration （MIC） drug sensitivity test was performed on the detected C. jejuni， and some strains were selected for whole genome sequencing and MLST analysis. ResultsA total of 823 samples of diarrhea disease were collected， and 32 strains of C. jejuni were detected， with a detection rate of 3.89%. Out of 600 poultry related samples， 62 strains of C. jejuni were detected， with a detection rate of 10.33%. Human multidrug resistance reached 93.75% （30/32）， while avian multidrug resistance reached 100.00%（62/62）. The top four drug resistance rates of human and avian C. jejuni were azithromycin （100.00% from humans and 100.00% from birds）， naphthoic acid （93.75% from humans and 87.10% from birds）， ciprofloxacin （90.63% from humans and 98.39% from birds）， and tetracycline （84.38% from humans and 98.39% from birds）. The relatively low resistance strains of human derived C. were erythromycin， chloramphenicol， and thalithromycin. The relatively low resistance strains of avian C. jejuni were erythromycin， clindamycin， and flufenicol. MLST analysis showed that the selected 16 strains of bacteria were divided into 9 ST types， among which the evolutionary relationship of avian C. jejuni was relatively concentrated， while human C. jejuni was relatively dispersed. It was found that one strain of avian C. jejuni was closely related to two strains of human C. jejuni. ConclusionsC. jejuni infection is severe in patients with diarrhea in this region， with a detection rate second only to salmonella and Vibrio parahaemolyticus. C. jejuni infection in poultry is relatively common， and both are highly resistant. Therefore， monitoring and control should be strengthened. MLST analysis shows new ST types in both avian and human sources of C. jejuni， indicating the emergence of new mutations that require continuous monitoring to avoid the epidemics caused by new strains. The isolated strains with close genetic relationships between avian and human sources reveal the evidence of the spread of C. jejuni from poultry to humans. Therefore it is necessary to strengthen the monitoring of C. jejuni in relevant samples from breeding farms.

ObjectiveTo determine the drug sensitivity and molecular typing characteristics of Klebsiella pneumoniae isolated from meat and diarrhea samples in a local area. MethodsSeventy-one strains of K.pneumoniae were isolated from 118 meat food （chicken and pork） randomly sampled in the markets in Jinshan District， Shanghai， 2020‒2021， and 1 499 diarrhea samples from outpatient diarrhoea patients in hospitals in the same district. Then drug susceptibility testing was conducted by micro-broth dilution method， and sequence identity was determined by pulsed field gel electrophoresis（PFGE）. ResultsThe overall detection rate of K.pneumoniae in meat was 11.86% （14/118）， with detection rate 20.93% （9/43） in chicken and 6.67% （5/75） in pork. The difference in detection between meats was statistically significant （χ²=5.317，P<0.05）. The detection rate of K.pneumoniae in diarrhea samples was 3.80% （57/1 499）. Furthermore， the isolated strains showed the highest resistance to ampicillin at 76.06%. The multi-drug resistant strains included 5 of human origin （8.77%） and 2 of foodborne origin （14.28%）. Additionally， 1 foodborne imipenem-resistant strain was detected. A total of 71 strains of K.pneumoniae were found to have 70 banding types， with similarity ranging from 39.4% to 100%， suggesting genetic diversity. ConclusionK.pneumoniae isolated from foodborne and diarrhea samples showed multi-drug resistance in Jinshan District， . with scattered PFGE banding patterns. It is recommended to strengthen the monitoring of this pathogen in the population and animal food， and be alert to the emerging multi-drug resistant strains and risk of food chain transmission.