#Bacterial #Colonization and Life-Threatening #RSV #Infection in #children

 

Highlights

• Respiratory tract bacterial colonization was highly prevalent among RSV-infected children.

• Moraxella catarrhalis colonization was significantly associated with mild RSV disease.

• Haemophilus influenzae carriage showed a trend toward increased severity.

• Household crowding independently correlated with severe RSV outcomes.

• Airway microbiota may modulate RSV clinical outcomes.

Abstract

Background

Respiratory syncytial virus is a major cause of acute respiratory infection in children. While most cases are mild, some progress to life-threatening disease. The role of bacterial colonization in shaping respiratory syncytial virus outcomes remains incompletely understood.

Objective

To evaluate the association between respiratory tract bacterial colonization and respiratory syncytial virus disease severity in children.

Study design

Prospective cohort study conducted during 2019 and 2023. Children ≤24 months hospitalized with confirmed positive respiratory syncytial virus infection were enrolled. Clinical and epidemiological data were collected. respiratory syncytial virus subtypes, viral load, and detection of Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis were determined by qPCR.

Results

401 patients were hospitalized with acute respiratory infection, of which 172 (42.9%) had confirmed respiratory syncytial virus infection. Among them, 15 (8.7%) developed life-threatening disease. Bacterial colonization was highly prevalent (92.4%): H. influenzae (68%), S. pneumoniae (64.5%), and M. catarrhalis (52.9%). M. catarrhalis colonization was associated with mild disease (p=0.003), while H. influenzae showed a trend toward increased severity (p=0.054). Viral subtype and viral load were not linked to severity. Household crowding was independently associated with more severe disease (p=0.031).

Conclusions

Our results support the growing evidence that airway microbiota modulates respiratory syncytial virus outcomes and highlights M. catarrhalis as potential microbial determinant of disease progression.

Source: 

Link: https://www.sciencedirect.com/science/article/abs/pii/S1386653225001337?dgcid=rss_sd_all

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Genomic profiling of #cefotaxime-resistant #Haemophilus influenzae from #Norway and #Sweden reveals extensive expansion of virulent #MDR international clones

Abstract

Cefotaxime-resistant Haemophilus influenzae (CRHI) are a global concern, but little is known about their molecular epidemiology. The goal of this study was to perform genomic profiling of 191 CRHI from Norway (n = 183) or Sweden (n = 8) (2006–2018) and assess clonal spread using core genome multilocus sequence typing (cgMLST)-based Life Identification Number (LIN) codes based on whole genome sequencing (Ion Torrent). Cefotaxime resistance was confirmed with broth microdilution minimal inhibitory concentration (MIC), interpreted with the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints. 35.7% of isolates with cefotaxime gradient MIC of 0.25 mg/L were falsely resistant. All but two isolates (blood) were non-invasive, and all but two (serotype f) were non-typeable. Characterization included calling of resistance determinants, ftsI typing (penicillin-binding protein 3, PBP3), and classification of PBP3-mediated beta-lactam resistance (rPBP3), with assignment to rPBP3 stage and group. All isolates had rPBP3-defining substitutions, and 78.5% were stage 3 (L389F positive). Beta-lactam MICs correlated well with rPBP3 genotypes. Significant proportions of stage 3 isolates were cross-resistant to ceftriaxone (86.0%) and meropenem (meningitis breakpoints, 26.0%). The CRHI prevalence in Norway doubled during the study period and approached 1%. A shift from stage 2 to stage 3 rPBP3 in 2011–2012 led to emergence of CRHI with higher beta-lactam MICs and co-resistance to multiple non-beta-lactams, including extensively drug-resistant (XDR) strains. The shift was driven by transformation with two distinct variants of the transpeptidase region and multiclonal expansion. 66.0% of the isolates belonged to 27 clusters. Ten clusters or singletons belonged to international CRHI clones represented in the PubMLST database. The study provides new insight into CRHI evolution, resistance profiles, and clonal dynamics in a period when this phenotype went from exceptional to unusual in Europe. International CRHI clones are described for the first time, including eight high-risk clones associated with invasive disease, calling for enhanced genomic surveillance. LIN coding, supplemented with ftsI typing and rPBP3 staging, is well-suited for definition of CRHI clones. LIN9, defined by ≤ 10 allelic differences, offered the highest resolution level fully supported by maximum likelihood core genome phylogeny and is proposed as a global standard for genomic surveillance of H. influenzae.

Source: Frontiers in Microbiology, https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1601390/full

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