Objective: To investigate the serotype and drug resistance of 815 Salmonella isolates from Hunan Province, so as to provide insights into management of Salmonella infections. Methods: Salmonella isolates were collected from stool samples of foodborne diarrheal patients and food samples in Hunan Province from 2020 to 2021, and serotyped. Antimicrobial susceptibility test was performed using the broth microdilution method. Results: A total of 10 groups and 39 serotypes were characterized in 815 Salmonella isolates. Among the 646 Salmonella isolates of human sources, 388 isolates were identified as serogroup B (60.06%), with S. typhimurium and its variants aspredominant serotypes (364 isolates, 56.35%), and among 169 foodborne isolates, 61 isolates were characterized as serogroup B (36.09%) with S. london as the predominant serotype (26 isolates, 15.38%). There were 597 antimicrobial resistant Salmonella isolates of human sources, with a drug resistance rate of 92.41%, and the percentage of ampicillin resistance was 81.58%. There were 140 foodborne antimicrobial resistant isolates, with a drug resistance rate of 82.84%, and the proportion of tetracycline resistance was 72.78%. However, Salmonella isolates from both humans and foods were sensitive to imipenem. In addition, there were 577 multidrug resistant Salmonella isolates, including 490 multidrug resistant isolates of human sources and 87 foodborne multidrug resistant isolates. Conclusions S. typhimurium and its variants and S. london were predominant serotypes of Salmonella isolates from 815 foodborne diarrheal patients and food samples in Hunan Province from 2020 to 2021, and a high rate of multidrug resistance was detected.

Acute respiratory tract infection is the most common infectious disease in children, which seriously threatens children′s health.Rapid and accurate etiological diagnosis is of great significance for the clinical treatment and control of these diseases.Pathogen nucleic acid test was applied and became the main method of respiratory tract infection diagnosis for its high sensitivity and specificity.To regulate the application of pathogen nucleic acid amplification test in respiratory tract infection in children, improve the diagnosis level, expert consensus on nucleic acid amplification test of respiratory pathogens in children was prepared to guide the application and promote pathogens diagnosis ability.

Objective:To understand the characters of norovirus infection in children with acute diarrhea in Beijing from 2014 to 2019.Methods:Fecal specimens were collected from children with acute diarrhea visiting the hospital affiliated to the Capital Institute of Pediatrics from April 2014 to December 2019 for norovirus screening by reverse transcription-polymerase chain reaction (RT-PCR). Then RdRp gene and VP1 gene of norovirus (NoV) were amplified and sequenced from positive specimens and then genotyped by Norovirus Genotyping Tool 2.0.Results:Fecal specimens were collected from 2 577 cases with acute diarrhea and tested for NoV RNA in this study, of which 484 cases (18.78%, 484/2 577) were positive for NoV. NoV infection can occur all year round, with obvious seasonal distribution, the epidemic peak is in autumn and winter. There was no gender difference in the detection of NoV ( χ2=1.77, P=0.183). 399 specimens genotyped by VP1 gene with 98.25% (392/399) being GII and GII.4 Sydney as the mainly genotype (52.13%, 208/399), followed by GII.3 (19.8%, 79/399) and GII.2 (18.5%, 74/399). Then 267 specimens also were genotyped by RdRp region, which revealed that the main genotype was GII.P31 (57.3 %, 153/267), followed by GII.P12 (15.36%, 41/267) and GII.P16 (14.98 %, 40/267). Dual-typing revealed that various combination strains, GII.4 Sydney[P31] (53.18%, 142/267) as the major combination, followed by GII.3[P12] and GII.2[P16] (15.36%, 41/267 and 10.49%, 28/267). While GII.3[P12] showed a downward trend, GII.4 Sydney[P16] increased gradually. Conclusions:Norovirus is an important pathogen of acute diarrhea in children in Beijing, from 2014 to 2019, with various prevalent genotypes.

Objective:To investigate the molecular epidemiology of norovirus associated with pediatric acute gastroenteritis in Beijing under the Working Mechanism for Joint Prevention and Control of the Epidemic in 2020.Methods:This was a retrospective, repeated cross-sectional study. Fecal or vomit samples (1 213 cases) were collected from children visited the Capital Institute of Pediatrics Affiliated Children′s Hospital for acute gastroenteritis from January 1 to December 31, 2020. First, real-time reverse PCR (RT-PCR) was used to screen the samples for norovirus, and then RdRp gene and capsid gene VP1 of norovirus-positive samples were amplified by conventional RT-PCR for genotyping based on the nucleotide sequence. The χ 2 test was used to compare the positive rates and genotypes of norovirus among different specimen types, genders of children, and different age groups. Results:Among the 1 213 samples were collected, 215 samples were positive for norovirus, with a positivity rate of 17.7% for the whole year. The peak of norovirus infection observed mainly in the cold seasons, as the positive rates were 28.6% (18/63), 26.2% (16/61), 22.8% (77/338) and 17.1% (89/520) in January, October, November and December, respectively. The positive rate of norovirus in fecal sample was significantly higher than that in vomit sample (χ 2 = 9.692, P<0.01). There was no significant difference between genders (χ 2=0.041, P>0.05), but significant difference was found between age groups with the highest rate in the 6-48 months group (χ2=103.112, P<0.01). Three genogroups (GⅠ, GⅡ and GⅨ) of the circulating virus were detected by G-gene typing, and GⅡgenogroup was predominant, accounting for 98.5% (196/199). Among the GⅡ positive samples, genotype GⅡ.4 Sydney (55.1%, 108/196) was the most common, followed by GⅡ.2 (29.6%, 58/196), while the GⅡ.3 norovirus (10.2%, 20/196) which was common in previous years was not as much as before. Based on the P-type, GⅡ.P16 was predominant (61.5%, 96/156), followed by GII.P31 (19.9%, 31/156). The dual genotyping revealed that GⅡ.4 Sydney [P16] (36.4%, 56/154) and GⅡ.2 [P16] (24.7%, 38/154) were predominant. Conclusion:The prevalence of norovirus in children in 2020 in Beijing is not much different from those of the previous years, but the genotypes composition has changed significantly, and there are multiple genotypes circulating simultaneously.

Objective:To investigate the spectrum of pathogenic agents in pediatric patients with acute respiratory infections (ARI) during the outbreak of coronavirus infectious diseases 2019 (COVID-19).Methods:Three groups of children were enrolled into the prospective study during January 20 to February 20, 2020 from Capital Institute of Pediatrics, including children in the exposed group with ARI and epidemiological history associated with COVID-19 from whom both pharyngeal and nasopharyngeal swabs were collected, children in the ARI group without COVID-19 associated epidemiological history and children in the screening group for hospital admission, with neither COVID-19 associated epidemiological history nor ARI. Only nasopharyngeal swabs were collected in the ARI group and screening group. Each group is expected to include at least 30 cases. All specimens were tested for 2019-nCoV nucleic acid by two diagnostic kits from different manufacturers. All nasopharyngeal swabs were tested for multiple respiratory pathogens, whilst the results from the ARI group were compared with that in the correspondence periods of 2019 and 2018 used by t or χ 2 test. Results:A total of 244 children were enrolled into three groups, including 139 males and 105 females, the age was (5±4) years. The test of 2019-nCoV nucleic acid were negative in all children, and high positive rates of pathogens were detected in exposed (69.4%, 25/36) and ARI (55.3%, 73/132) groups, with the highest positive rate for mycoplasma pneumoniae (MP) (19.4%, 7/36 and 17.4%, 23/132, respectively), followed by human metapneumovirus (hMPV) (16.7%, 6/36 and 9.8%, 13/132, respectively). The positive rate (11.8%, 9/76) of pathogens in the screening group was low. In the same period of 2019, the positive rate of pathogens was 83.7% (77/92), with the highest rates for respiratory syncytial virus (RSV) A (29.3%, 27/92), followed by influenza virus (Flu) A (H1N1) (19.6%, 18/92) and adenovirus (ADV) (14.1%, 13/92), which showed significant difference with the positive rates of the three viruses in 2020 (RSV A: χ 2=27.346, P<0.01; FluA (H1N1): χ 2=28.083, P<0.01; ADV: χ 2=7.848, P=0.005) . In 2018, the positive rate of pathogens was 61.0% (50/82), with the highest rate for human bocavirus (HBoV) (13.4%, 11/82) and followed by ADV (11.0%, 9/82), and significant difference was shown in the positive rate of HBoV with that in 2020 (χ 2=6.776, P=0.009). Conclusions:The infection rate of 2019-nCoV is low among children in Beijing with no family clustering or no close contact, even with epidemiological history. The spectrum of pathogens of ARI in children during the research period is quite different from that in the previous years when the viral infections were dominant. MP is the highest positively detected one among the main pathogens during the outbreak of COVID-19 in Beijing where there is no main outbreak area.

Objective: To analyze and compare the epidemiological features of prevalent influenza A viruses in children in Beijing during 13 consecutive surveillance seasons from 2004 to 2017. Methods: This was a repeated cross section study. Throat swabs were collected weekly from children with influenza-like illnesses (ILI) who presented to the outpatient/emergency department of Children's Hospital, Capital Institute of Pediatrics during the period from September, 2004 to August, 2017. All of the specimens were inoculated into Madin Darby canine kidney (MDCK) cells to isolate influenza viruses followed by identifying different types of influenza viruses with reference antisera by hemagglutination-inhibition assay. Descriptive statistics, t test and chi-square test were used to analyze the characteristics of prevalent influenza and characteristics of children infected with different types of influenza viruses. Results: Out of 10 984 specimens from ILI tested for influenza viruses, 1 052 (9.6%) were positive for influenza A viruses, and the positive rate was higher than that of influenza B viruses (6.7%, 741/10 984). Out of 1 052 cases positive for influenza A viruses, 70 cases of seasonal H1N1, 302 cases of 2 009 pandemic H1N1 and 680 cases of H3N2 were identified. The mean age of children with influenza A was (4.2±2.9) years, in whom 55.5% (584/1 052) were male. The mean age of children infected with seasonal H1N1, 2009 pandemic H1N1 and H3N2 was (4.6±2.1) , (4.3±3.1) and (4.2±2.9) years, respectively. There was no significant difference in the mean age among children infected with different subtypes of influenza A viruses (seasonal H1N1 vs. H3N2: t=1.139, P=0.255; 2009 pandemic H1N1 vs. H3N2: t=0.631, P=0.528; seasonal H1N1 vs. 2009 pandemic H1N1: t=0.720, P=0.472), while the mean age of children with influenza B was higher than that of the patients with influenza A ((5.2±2.7) vs. (4.2±2.9) years, t=7.120, P=0.000). The infection rate of influenza A in children with each age group was significantly different from that of influenza B. The infection rate of 2009 pandemic H1N1 and H3N2 increased with age, except for the patients of 0-6 months. Meanwhile, the infection rate of H3N2 in children aged 6 months to 12 years was higher than that of seasonal H1N1 and 2009 pandemic H1N1 (all P<0.05). The influenza A epidemic peaked earlier than that of influenza B when the positive rate of influenza A was higher than that of influenza B, and vice versa. After 2009, circulating strain was substituted by 2009 pandemic H1N1 virus with higher positive rate, while previous seasonal H1N1 had not been detected. The 2009 pandemic H1N1 circulated at high level in two consecutive seasons, which was followed by low level in next season. H3N2 epidemic peaked mostly in winter and spring each year, however, the epidemic wave of H3N2 with high virulence occurred so early in the summer in the year of 2009 H1N1 pandemic. Conclusions The characteristics of prevalent influenza A viruses in children were different among 13 surveillance seasons from 2004 to 2017 in Beijing. The 2009 pandemic H1N1 and H3N2 became the predominant strains of influenza A virus.

Objective: To investigate the relationship between human bocavirus 2 (HBoV2) infection and acute diarrhea in children younger than 5 years of age in a case-control study. Methods: This was a prospective case-control study. During May 2016 to December 2016, fecal specimens were collected from children ≤5 years of age with acute diarrhea who visited the Affiliated Children's Hospital of Capital Institute of Pediatrics (case group), or from children ≤5 years of age without diarrhea from Longtan Community Medical Service Center, Beijing (control group). The case group (n=240) and the control group (n=240) were divided into 8 age subgroups: ≤1 month old, >1-3 months old, >3-6 months old, >6-12 months old,>1-2 years old,>2-3 years old,>3-4 years old and >4-5 years old, and there were 30 cases in each age subgroup. The specimens were tested for 7 types of diarrhea-associated viruses, especially for HBoV2 by real-time PCR method. The HBoV2 viral load was predicted according to the cycle threshold (Ct). Finally, t-test was used to compare the differences between groups. Results: In the case group (n=240), the positive rate of norovirus was 16.7% (40 cases); rotavirus, 10.8% (26 cases); HBoV2, 7.5% (18 cases); adenovirus, 7.1% (17 cases); astrovirus, 6.3% (15 cases); parachovirus, 3.8% (9 cases); and Aich virus, 0.4% (1 case). The positive rates of HBoV2 in case group (7.5%, 18 cases) and control group (5.0%, 12 cases) showed no significant difference (χ²=1.280, P=0.258), as well as in different age groups (all P>0.05) . However, the mean viral load of the HBoV2 in the case group (1×10⁹copies/L with cycle threshold (Ct) 25.8) was higher than that of control group (1×10⁵copies/L with Ct 33.8), showing a significant difference (t=0.597, P=0.000). Conclusions Norovirus and rotavirus are still the important viral pathogens in children with acute diarrhea. A higher load of HBoV2 may indicate a higher risk of acute diarrhea in children ≤5 years of age in Beijing.

Objective Compare the HPV infection characters between women in different geographic area of Ankang (south of Shaanxi) and Yanan (north of Shaanxi),to provide evidence based reference for cervical cancer control.Methods PCR amplification in vitro combined reverse dot-blot hybridization assay were used to analyze HPV genotypes of 7 912 cases from Ankang City Center Hospital,and 3 543 cases from Yanan Affiliated Hospital of Yanan Medical University from June 2012 to July 2016,and compared HPV infection rate,age and hypotype distribution of the cases.Results The HPV infection rate of Ankang area was 21.75％ (1 721/7 912),and Yanan area was 41.41％ (1 402/1 721).The percentage of HPV positive women with high-risk hypotype was 81.46％ (1 402 1 721) in Ankang and 86.16％ (1 264/1 467) in Yanan,with low-risk hypotype was 11.04％ (190/1 721) in Ankang and 7.23％ (106/1 467) in Yanan,with high and low risk hypotype was 7.50％ (129 147) in Ankang and 6.61％ (97/1 467) in Yanan.The women more than 60 year old were higher HPV prevalence age group.The HPV infection rate of this age group was 30.41％ (104/342) in Ankang,and 50.00 ％ (60/120) in Yanan.Yanan's HPV infection rate was obviously higher than Ankang.The popular HPV hypotypes in Yanan were same with that in Ankang.The most popular high-risk hypotypes were HPV16,58 and 52,the most popular low-risk hypotypes were 6,11 and 81.Conclusion The HPV infection rate were rather high in all age group.The most popular HPV hypotypes were same between Ankang and Yanan area.But Yanan's HPV infection rate was obviously higher than Ankang (P＜ 0.01).The causes need further explore.

Objective: To evaluate the clinical value of a rapid respiratory syncytial virus (RSV) antigen detection in point-of-care testing (POCT). Method: A total of 209 specimens, including 78 throat swabs (TS) and 131 nasopharyngeal aspirates (NPAs), were collected from inpatients who visited the Children′s Hospital Affiliated to the Capital Institute of Pediatrics and were diagnosed as acute respiratory infection from 5 January to 7 February, 2015. These specimens were tested for RSV by a rapid antigen detection kit which was compared with reverse transcription polymerase chain reaction (RT-PCR) and direct immunofluorescence assay (DFA) for RSV detection. Result: Compared with DFA for NPAs, the sensitivity and specificity of rapid antigen detection were 83.9% and 97.3%, respectively, with Kappa value of 0.86; Compared with RT-PCR, the sensitivity (NPAs, 74.2%; TS, 77.8%) and specificity (NPAs, 100.0%; TS, 92.0%) of rapid antigen detection were high, too, with Kappa value of 0.74 in NPAs and 0.62 in TS. However, the RSV positive rate of rapid antigen detection in TS (21.7%) from pediatric patients with acute lower respiratory tract infection was lower than that in NPAs (78.3%), as well as that of RT-PCR (7.3% in TS verse 78% in NPAs). The RSV rapid antigen detection kit can be finished in about 10 minutes. Conclusion With characteristics of high specificity, high sensitivity, being rapid, efficient and easy to operate in comparison with DFA and RT-PCR, RSV rapid antigen detection in this study is suitable for POCT. For pediatric patients with acute respiratory tract infection, NPA was better than TS for RSV detection.

Objective: To investigate the clinical characteristics of respiratory syncytial virus(RSV)bronchiolitis and molecular biological characteristics of RSV in children in Beijing. Method: In a systematic retrospective study, 2 296 nasopharyngeal aspirates (NPA) were collected from children diagnosed with bronchiolitis from July 2006 to June 2016 for respiratory virus screening using direct immunofluorescence assay (DFA). For specimens positive for RSV, subgroup A or B was confirmed by real time RT-PCR and genotype of RSV was determined by amplifying the full G glycoprotein gene and sequencing. Clinical data were evaluated by the modified Tal score to compare the severity between RSV subtypes, as well as genotypes. Statistical analyses were performed using t test, Mann-Whitney U test and χ² test. Result: In 2 296 bronchiolitis cases, 961(41.9%) were RSV positive, including 719(74.8%) RSV A and 236 (24.6%) RSV B. The dominant RSV subtype changed from year to year: A-A-B-B-A-A-B-AB-A-AB and more bronchiolitis cases were identified in RSV A dominant years. Six genotypes of RSV A (NA1, NA2, NA3, NA4, GA5 and ON1) and 5 genotypes of RSV B (BA3, BA7, BA9, BA10 and CB1) were prevalent in Beijing. The dominant genotypes of RSV A were NA1 (55.9%) with high rates (50.0%-100%) before 2014 and ON1 (39.1%), mainly detected after 2014, while BA9 (90.6%) was the absolute dominant RSV B genotype. No significant difference in the severity of bronchiolitis was shown between cases of RSV A and B. Children positive for NA1 were more likely to stay longer in hospital (Median time: 8 days) compared to the group positive for ON1(Median time: 6 days ) (U=1.035, P=0.005) and had higher proportion of moderate to severe degree symptoms (Moderate: 41.0%, Severe: 10.0%) compared with ON1 group (Moderate: 22.9%, Severe: 4.3%) (U=9.785, P=0.008). In the group positive for ON1, more children had fever (ON1: 38.6%, NA1: 15.0%) (χ²=11.064, P=0.001) and more were younger than 3 months(ON1: 54.3%, NA1: 33.0%) (χ²=77.408, P<0.001). Conclusion The dominant RSV subgroup changed from year to year with a shifting pattern. The correlation between RSV genotypes and the severity of disease was documented in the study.