Analysis of phylogenetic diversity and in vitro adherence characteristics of respiratory syncytial virus and Streptococcus pneumoniae clinical isolates obtained during pediatric respiratory co-infections

Interactions between respiratory syncytial virus and Streptococcus pneumoniae in the pathogenesis of childhood respiratory infections: a systematic review

Lower respiratory tract infections, commonly caused by respiratory syncytial virus (RSV) or Streptococcus pneumoniae (pneumococcus), pose a substantial global health burden, especially in children younger than 5 years of age. A deeper understanding of the relationship between RSV and pneumococcus would aid the development of health-care approaches to disease prevention and management. We completed a systematic review to identify and assess evidence pertaining to the relationship between RSV and pneumococcus in the pathogenesis of childhood respiratory infections. We found mechanistic evidence for direct pathogen-pathogen interactions and for indirect interactions involving host modulation. We found a strong seasonal epidemiological association between these two pathogens, which was recently confirmed by a parallel decrease and a subsequent resurgence of both RSV and pneumococcus-associated disease during the COVID-19 pandemic. Importantly, we found that pneumococcal vaccination was associated with reduced RSV hospitalisations in infants, further supporting the relevance of their interaction in modulating severe disease. Overall evidence supports a broad biological and clinical interaction between pneumococcus and RSV in the pathogenesis of childhood respiratory infections. We hypothesise that the implementation of next-generation pneumococcal and RSV vaccines and monoclonal antibodies targeting RSV will act synergistically to reduce global morbidity and mortality related to childhood respiratory infections.

Dynamic Interaction Between Mucosal Immunity and Microbiota Drives Nose and Pharynx Homeostasis of Common Carp (Cyprinus carpio) After SVCV Infection

The crosstalk between the immune system and microbiota drives an amazingly complex mutualistic symbiosis. In mammals, the upper respiratory tract acts as a gateway for pathogen invasion, and the dynamic interaction between microbiota and mucosal immunity on its surface can effectively prevent disease development. However, the relationship between virus-mediated mucosal immune responses and microbes in lower vertebrates remains uncharacterized. In this study, we successfully constructed an infection model by intraperitoneally injecting common carp (Cyprinus carpio) with spring viremia of carp virus (SVCV). In addition to the detection of the SVCV in the nose and pharynx of common carp, we also identified obvious histopathological changes following viral infection. Moreover, numerous immune-related genes were significantly upregulated in the nose and pharynx at the peak of SVCV infection, after which the expression levels decreased to levels similar to those of the control group. Transcriptome sequencing results revealed that pathways associated with bacterial infection in the Toll-like receptor pathway and the Nod-like receptor pathway were activated in addition to the virus-related Rig-I-like receptor pathway after SVCV infection, suggesting that viral infection may be followed by opportunistic bacterial infection in these mucosal tissues. Using 16S rRNA gene sequencing, we further identified an upward trend in pathogenic bacteria on the mucosal surface of the nose and pharynx 4 days after SVCV infection, after which these tissues eventually reached new homeostasis. Taken together, our results suggest that the dynamic interaction between mucosal immunity and microbiota promotes the host to a new ecological state.

Pneumococcal septic shock after neonatal respiratory syncytial virus bronchiolitis: A case report and literature review

BACKGROUND

Bronchiolitis is a common cause of hospitalisation of infants less than a year old, with most infants recovering without complications. Respiratory syncytial virus (RSV) is a leading cause of bronchiolitis. Antimicrobial stewardship programmes do not recommend antibiotics for viral infections in neonates unless documented evidence of secondary bacterial infection is present.

CASE REPORT

We present the case of a 7-day-old infant admitted to hospital with chest retractions and fever. The baby was hospitalised, empirical antibiotic therapy was administered, and non-invasive ventilation was started. When the viral aetiology was identified and clinical conditions improved, antibiotics were discontinued. However, after 48 hours, the newborn's condition worsened because of pneumococcal septic shock. Intravenous fluids, catecholamine support, and wide-spectrum antibiotics were administered. Non-invasive ventilation was re-started and continued until the full recovery.

CONCLUSIONS

There is increasing evidence that RSV and S. pneumoniae co-infect and interact with each other, thus increasing respiratory diseases' severity. We provide a brief overview of the main international guidelines for managing bronchiolitis. Guidelines suggest avoidance of antibiotics use when the diagnosis of viral bronchiolitis is confirmed. We discuss the uncertainties regarding antibiotic use, especially in younger infants, who are more exposed to risks of bacterial superinfection.