Evolving insights into the epidemiology of Moraxella species bloodstream infection from two decades of surveillance in Queensland, Australia

The epidemiology of Moraxella species bloodstream infection (BSI) is poorly defined due to their rarity. We sought to determine the incidence, risk factors, and outcomes of Moraxella species BSI in a large Australian population. All Moraxella species BSIs in patients admitted to Queensland (population estimate 5 million) public health facilities between 2000 and 2019 and submitted to Queensland pathology laboratory-based surveillance were included. Clinical and hospitalisation data were matched with laboratory-based surveillance data. Incidence rate ratios (IRR) with 95% confidence intervals (CI) were calculated. In total, 375 incident Moraxella species BSI occurred during 86 million person-years of surveillance, with an annualised age and sex standardised incidence of 4.3 per million residents. Isolates were most commonly identified as M. catarrhalis (n = 128; 34%) and community-associated (n = 225; 60%). Incidence was highest in infants, with increasing age associated with lower incidence rate. Males were at higher risk (incidence 2.9 vs. 2.0 per million, IRR1.4; 95% CI, 1.2-1.8), this was most pronounced at age extremes. Two-thirds of adults and 43% of children with Moraxella BSI had at least one comorbid illness. When compared to infections in adults, children were more likely to have community-associated disease, and a head and neck source focus of infection. The all-cause 30-day case-fatality rate was 4% (15/375) and this was significantly higher among adults (14/191; 7% vs 1/183; 1%; p < 0.001). Our findings demonstrate the low burden of Moraxella species BSI in a state-wide cohort, for which young children have the highest risk.

Increased Moraxella and Streptococcus species abundance after severe bronchiolitis is associated with recurrent wheezing

BACKGROUND

The role of the airway microbiome in the development of recurrent wheezing and asthma remains uncertain, particularly in the high-risk group of infants hospitalized for bronchiolitis.

OBJECTIVE

We sought to examine the relation of the nasal microbiota at bronchiolitis-related hospitalization and 3 later points to the risk of recurrent wheezing by age 3 years.

METHODS

In 17 US centers researchers collected clinical data and nasal swabs from infants hospitalized for bronchiolitis. Trained parents collected nasal swabs 3 weeks after hospitalization and, when healthy, during the summer and 1 year after hospitalization. We applied 16S rRNA gene sequencing to all nasal swabs. We used joint modeling to examine the relation of longitudinal nasal microbiota abundances to the risk of recurrent wheezing.

RESULTS

Among 842 infants hospitalized for bronchiolitis, there was 88% follow-up at 3 years, and 31% had recurrent wheezing. The median age at enrollment was 3.2 months (interquartile range, 1.7-5.8 months). In joint modeling analyses adjusting for 16 covariates, including viral cause, a 10% increase in relative abundance of Moraxella or Streptococcus species 3 weeks after day 1 of hospitalization was associated with an increased risk of recurrent wheezing (hazard ratio [HR] of 1.38 and 95% high-density interval [HDI] of 1.11-1.85 and HR of 1.76 and 95% HDI of 1.13-3.19, respectively). Increased Streptococcus species abundance the summer after hospitalization was also associated with a greater risk of recurrent wheezing (HR, 1.76; 95% HDI, 1.15-3.27).

CONCLUSIONS

Enrichment of Moraxella or Streptococcus species after bronchiolitis hospitalization was associated with recurrent wheezing by age 3 years, possibly providing new avenues to ameliorate the long-term respiratory outcomes of infants with severe bronchiolitis.

Distinct nasal airway bacterial microbiotas differentially relate to exacerbation in pediatric patients with asthma

BACKGROUND

In infants, distinct nasopharyngeal bacterial microbiotas differentially associate with the incidence and severity of acute respiratory tract infection and childhood asthma development.

OBJECTIVE

We hypothesized that distinct nasal airway microbiota structures also exist in children with asthma and relate to clinical outcomes.

METHODS

Nasal secretion samples (n = 3122) collected after randomization during the fall season from children with asthma (6-17 years, n = 413) enrolled in a trial of omalizumab (anti-IgE) underwent 16S rRNA profiling. Statistical analyses with exacerbation as the primary outcome and rhinovirus infection and respiratory illnesses as secondary outcomes were performed. Using A549 epithelial cells, we assessed nasal isolates of Moraxella, Staphylococcus, and Corynebacterium species for their capacity to induce epithelial damage and inflammatory responses.

RESULTS

Six nasal airway microbiota assemblages, each dominated by Moraxella, Staphylococcus, Corynebacterium, Streptococcus, Alloiococcus, or Haemophilus species, were observed. Moraxella and Staphylococcus species-dominated microbiotas were most frequently detected and exhibited temporal stability. Nasal microbiotas dominated by Moraxella species were associated with increased exacerbation risk and eosinophil activation. Staphylococcus or Corynebacterium species-dominated microbiotas were associated with reduced respiratory illness and exacerbation events, whereas Streptococcus species-dominated assemblages increased the risk of rhinovirus infection. Nasal microbiota composition remained relatively stable despite viral infection or exacerbation; only a few taxa belonging to the dominant genera exhibited relative abundance fluctuations during these events. In vitro, Moraxella catarrhalis induced significantly greater epithelial damage and inflammatory cytokine expression (IL-33 and IL-8) compared with other dominant nasal bacterial isolates tested.

CONCLUSION

Distinct nasal airway microbiotas of children with asthma relate to the likelihood of exacerbation, rhinovirus infection, and respiratory illnesses during the fall season.

Moraxella species: infectious microbes identified by use of time-of-flight mass spectrometry

PURPOSE

To report the clinical manifestations, identification, antimicrobial susceptibilities, and treatment outcomes of ocular infections caused by Moraxella species.

STUDY DESIGN

Retrospective study.

PATIENTS AND METHODS

The medical records of all patients treated at the Departments of Ophthalmology of the Ogaki Municipal Hospital and the Gifu University Graduate School of Medicine for ocular infections caused by Moraxella species between January 2011 and June 2017 were examined. The stored Moraxella species isolated from ocular samples were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), molecular identification, and the biochemical properties.

RESULTS

Sixteen eyes of 16 patients were treated for Moraxella ocular infections. The patients' median age was 72 years. A predisposing systemic or ocular condition was identified in 15 of the patients. Nine of the patients developed keratitis; four, conjunctivitis; and three, blebitis. M lacunata (6 eyes), M catarrhalis (6), M nonliquefaciens (3), and M osloensis (1) were identified by MALDI-TOF MS. All isolates were sensitive to levofloxacin, tobramycin, ceftazidime, ceftriaxone, and cefazolin. Twelve patients with keratitis or blebitis were treated with various topical antimicrobial combinations, and systemic antibiotics were used in 10 of the 12 patients. The mean time for the complete closure of the epithelial defects with keratitis was 24 days. The visual outcomes after treatment were favorable except in 1 keratitis patient who underwent enucleation.

CONCLUSIONS

The use of duo-therapy with a combination of fluoroquinolone and cefmenoxime should be considered in cases nonresponsive to monotherapy, such as keratitis and bleb-associated infections. MALDI-TOF MS is useful for the identification of Moraxella to the species level.