Refractory Mycoplasma pneumoniae pneumonia (RMPP) is a severe state of M. pneumoniae infection that has attracted increasing universal attention in recent years. The pathogenesis of RMPP remains unknown, but the excessive host immune responses as well as macrolide resistance of M. pneumoniae might play important roles in the development of RMPP. To improve the prognosis of RMPP, it is mandatory to recognize RMPP in the early stages, and the detection of macrolide-resistant MP, clinical unresponsiveness to macrolides and elevated proinflammatory cytokines might be clues. Timely and effective anti-mycoplasmal therapy and immunomodulating therapy are the main strategies for RMPP.

Haemophilus influenzae (H. influenzae) is a significant pathogen responsible for causing respiratory tract infections and invasive diseases, leading to a considerable disease burden. The Haemophilus influenzae type b (Hib) conjugate vaccine has notably decreased the incidence of severe infections caused by Hib strains, and other non-typable H. influenzae (NTHi) serotypes have emerged as epidemic strains worldwide. As a result, the global epidemic trends and antibiotic resistance characteristics of H. influenzae have been altered. Researches on the virulence factors of H. influenzae, particularly the mechanisms underlying biofilm formation, and the development of anti-biofilm strategies hold significant clinical value. This article provides a summary of the epidemic trends, typing methods, virulence factors, biofilm formation mechanisms, and prevention strategies of H. influenzae. The increasing prevalence of NTHi strains and antibiotic resistance among H. influenzae, especially the high β-lactamase positivity and the emergence of BLNAR strains have increased clinical difficulties. Understanding its virulence factors, especially the formation mechanism of biofilm, and formulating effective anti-biofilm strategies may help to reduce the clinical impact. Therefore, future research efforts should focus on developing new approaches to prevent and control H. influenzae infections.

Objective: This study aimed to explore the epidemiological trend and clinical characteristics of respiratory syncytial virus (RSV) infection among inpatient children with lower respiratory tract infection (LRTI) before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: A retrospective study of inpatients with LRTI was conducted at the Department of Pulmonology, The Children’s Hospital, Zhejiang University School of Medicine (Hangzhou, China) from January 2019 to December 2021. All respiratory specimens were tested for common respiratory pathogens. The clinical data in children with RSV-induced LRTI in the past three years were collected and analyzed. Results: A total of 11,290 patients were enrolled, and RSV positive cases were 402 (7.6%), 288 (9.6%), 415 (13.8%) in 2019, 2020, 2021, respectively, with a significant statistical difference of the RSV positive rate among the three groups (p < 0.001). Most patients were under 2-year old, especially under 1-year old, and the median age of patients was 4 months, 5 months, 6 months in 2019, 2020, 2021, respectively, with a tendency to increase in age. In terms of the seasonal distribution, most patients of LRTI with RSV infection were admitted in winter, while in 2021 compared with in 2019, the cases significantly reduced in winter and increased in autumn. From 2019 to 2021, there was an increase in autumn trend year by year. Conclusion: RSV infection was still an important cause of hospitalization in children with LRTI after the outbreak of COVID-19, and its proportion increased gradually. LRTI caused by RSV is still more common in infants under 1-year old, but there is a trend of increasing in older children. What deserves the attention of pediatricians and Center for Disease Control is that the incidence of RSV infection continues to rise in autumn, and the difference in seasonal distribution is narrowed.

Objective: This study aimed to investigate the biofilm-forming ability, molecular typing, and antimicrobial resistance of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strains isolated from the respiratory tract of children and their correlation with clinical characteristics. Methods: All CA-MRSA strains were isolated from hospitalized children, and their presentation, molecular typing, antimicrobial susceptibility, and biofilm formation were investigated. The clinical characteristics were compared between the strong and weak biofilm producer groups. Results: Fifty-three CA-MRSA strains were isolated from the respiratory samples of 53 children, with nearly half of them being young infants (0– 12 months). Approximately, 88.7% (47/53) of the isolates were resistant to four or more antibiotics, mainly β-lactam antibiotics, lincosamides, and macrolides. Twelve sequence types (STs) and 20 subtypes of staphylococcal protein A (spa) typing were identified, with ST59-t437 (39.6%, 21/53) as the predominant subtype. All strains showed the ability to form biofilms. When compared to children with weak biofilm-forming CA-MRSA strains, those with strong biofilm-forming strains had higher proportions of lower respiratory tract infections (LRTI) (88.5% vs 59.3%), obvious cough symptoms (84.6% vs 51.9%), and severe chest imaging manifestations (76.9% vs 37.0%). Furthermore, a strong biofilm-forming ability significantly increased the risk of prolonged cough in children with LRTI (44.4% vs 14.3%), and a positive correlation between the duration of cough and the extent of biofilm formation was observed. Medical history investigation revealed that the strong biofilm-forming group had a much higher percentage of macrolides intake than the weak biofilm-forming group in the last month before admission (61.5% vs 14.8%). Conclusion: ST59-t437 was the most prevalent clone in CA-MRSA respiratory isolates among the hospitalized children. All CA-MRSA strains formed biofilms. The stronger the biofilm-forming ability, the more serious and prolonged were the respiratory symptoms.

The present study aimed to determine the effect of recombinant DNA vaccine-based human epidermal growth factor receptor-2 (HER2) and Interleukin 12 (IL-12) on the development of colonic carcinoma in mice and the potential immune mechanisms involved. Recombinant plasmids pVAX1-HER2, pVAX1-IL-12 and pVAX1-HER2-IL-12 were constructed, and injected into female mice intramuscularly (i.m.) followed by an electric pulse. The humoral and cellular immune responses after immunization were examined by enzyme linked immunosorbent assay (ELISA) and enzyme-linked immunospot assay (ELISPOT), respectively. To evaluate the anti-tumor efficacy of the plasmids, a mouse model with a HER2-expressing tumor was designed. Mice vaccinated with the HER2-IL-12 plasmid generated the strongest inhibition efficacy on the growth of HER2-expressing tumors and prolonged mouse survival. These observations emphasized the potential of IL-12 as an adjuvant for DNA vaccines and of vaccines based on HER2 and IL-12 as a promising treatment for colonic carcinoma.

Background: Bronchiolitis is a common cause of hospitalization in infants under 2 years of age. The epidemiological effects of changes in hygiene and social behaviors during COVID-19 restrictions on the disease is still debated. This study aimed to analyze the changes in the viral etiology of bronchiolitis in Hangzhou during the COVID-19 restriction period (2022) compared to the period following the easing of restrictions(2023). Methods: This study collected data on patients under 2 years of age who were admitted for bronchiolitis to the Department of Pulmonology at the Children’s Hospital, Zhejiang University School of Medicine (Hangzhou) from January, 1, 2022, to December 31, 2023. It also investigated seasonal variations in the incidence of bronchiolitis and pathogen distribution across different years. Results: This study included a total of 697 children with bronchiolitis, with a median age of 7.5 (4.2– 12.0) months. Of these, 68.9% were boys and 31.1% were girls. Compared to 2022, the number of bronchiolitis cases in 2023 (388 versus 309) and their proportion of lower respiratory tract infections (39.1% versus 28.2%) have significantly increased (p < 0.001). Whether in 2022 or 2023, respiratory syncytial virus (RSV) was the primary pathogen causing bronchiolitis among children under 12 months of age, while human rhinovirus (HRV) was the main pathogen in children aged 12– 24 months. There was a shift in the timing of the peak of several viruses including RSV, human metapneumovirus (HMPV) and parainfluenza virus (PIV) infections in 2023. However, the epidemic trend of HRV presented no significant changes between 2022 and 2023. Conclusion: The findings suggest that bronchiolitis hospitalizations increased markedly after COVID-19 restriction easing, particularly among children aged 12– 18 months. There was a shift in the timing of the peak of several viruses including RSV, HMPV and PIV infections in 2023, emphasizing the need for hospitals to anticipate potential irregularities in time in the future.