The evidence for non-typeable Haemophilus influenzae as a causative agent of childhood pneumonia

An infant mouse model of influenza-driven nontypeable Haemophilus influenzae colonization and acute otitis media suitable for preclinical testing of novel therapies

Nontypeable Haemophilus influenzae (NTHi) is a major otitis media (OM) pathogen, with colonization a prerequisite for disease development. Most acute OM is in children <5 years old, with recurrent and chronic OM impacting hearing and learning. Therapies to prevent NTHi colonization and/or disease are needed, especially for young children. Respiratory viruses are implicated in driving the development of bacterial OM in children. We have developed an infant mouse model of influenza-driven NTHi OM, as a preclinical tool for the evaluation of safety and efficacy of clinical therapies to prevent NTHi colonization and the development of OM. In this model, 100% of infant BALB/cARC mice were colonized with NTHi, and all developed NTHi OM. Influenza A virus (IAV) facilitated the establishment of dense (1 × 105 CFU/mL) and long-lasting (6 days) NTHi colonization. IAV was essential for the development of NTHi OM, with 100% of mice in the IAV/NTHi group developing NTHi OM compared with 8% of mice in the NTHi only group. Histological analysis and cytokine measurements revealed that the inflammation observed in the middle ear of the infant mice with OM reflected inflammation observed in children with OM. We have developed the first infant mouse model of NTHi colonization and OM. This ascension model uses influenza-driven establishment of OM and reflects the clinical pathology of bacterial OM developing after a respiratory virus infection. This model provides a valuable tool for testing therapies to prevent or treat NTHi colonization and disease in young children.

Efficient symptomatic treatment and viral load reduction for children with influenza virus infection by nasal-spraying Bacillus spore probiotics

Influenza virus is a main cause of acute respiratory tract infections (ARTIs) in children. This is the first double-blind, randomized, and controlled clinical trial examining the efficacy of nasal-spraying probiotic LiveSpo Navax, which contains 5 billion of Bacillus subtilis and B. clausii spores in 5 mL, in supporting treatment of influenza viral infection in pediatric patients. We found that the nasal-spraying Bacillus spores significantly shortened the recovery period and overall treatment by 2 days and increased treatment effectiveness by 58% in resolving all ARTIs' symptoms. At day 2, the concentrations of influenza virus and co-infected bacteria were reduced by 417 and 1152 folds. Additionally, the levels of pro-inflammatory cytokines IL-8, TNF-α, and IL-6 in nasopharyngeal samples were reduced by 1.1, 3.7, and 53.9 folds, respectively. Compared to the standard control group, treatment regimen with LiveSpo Navax demonstrated significantly greater effectiveness, resulting in 26-fold reduction in viral load, 65-fold reduction in bacterial concentration, and 1.1-9.5-fold decrease in cytokine levels. Overall, nasal-spraying Bacillus spores can support the symptomatic treatment of influenza virus-induced ARTIs quickly, efficiently and could be used as a cost-effective supportive treatment for respiratory viral infection in general.Clinical trial registration no: NCT05378022 on 17/05/2022.

High Prevalence of Group III-Like Mutations Among BLPACR and First Report of Haemophilus influenzae ST95 Isolated from Blood in China

Purpose

We aimed to evaluate antibiotic resistance and molecular epidemiological characteristics of non-invasive Haemophilus influenzae (H. influenzae) from pneumonia patients and analyze the whole genome of one invasive H. influenzae isolated from blood in pediatric patients.

Methods

Antibiotic susceptibility was tested using the turbidimetric method. β-lactamase-producing and serotyping genes were evaluated via multiplex polymerase chain reaction (PCR), and ftsI was amplified using high-fidelity PCR. Lastly, whole genome sequencing (WGS) was conducted using Illumina HiSeq and PacBio sequencing technology.

Results

We observed that the ampicillin (AMP) and amoxicillin/clavulanate (AMC) resistance rates of non-invasive H. influenzae were as high as 99.06% (after adjustment) and 49.53%, respectively. The β-lactamase gene of 106 AMP-resistant strains was bla_TEM-1 . Group III-like mutation accounted for 71.15% of β-lactamase-positive, AMC-resistant (BLPACR) strain mutants. The novel Asn-526→His mutation was present in one β-lactamase-negative AMP-susceptible (BLNAS) strain. Non-invasive H. influenzae strains all belonged to non-typeable H. influenzae (NTHi). In contrast, the invasive H. influenzae 108 isolated from blood in China belonged to H. influenzae type b (Hib). It belonged to sequence typing ST95 and exhibited sensitivity to all 11 antibiotics. Three prophages were identified, and the capb loci of the H. influenzae strain 108 revealed regions I-III exist in duplicate; however, complete deletion of IS1016 was only present in one of the copies.

Conclusion

Non-invasive H. influenzae NTHi with β-lactamase-positive was highly prevalent. Notably, group III-like mutations had increased prevalence among BLPACR strains. H. influenzae belonging to Hib and ST95 was first reported to cause sepsis in China.

Adherence of Nontypeable Haemophilus influenzae to Cells and Substrates of the Airway Is Differentially Regulated by Individual ModA Phasevarions

Adherence of nontypeable Haemophilus influenzae (NTHi) to the host airway is an essential initial step for asymptomatic colonization of the nasopharynx, as well as development of disease. NTHi relies on strict regulation of multiple adhesins for adherence to host substrates encountered in the airway. NTHi encode a phase-variable cytoplasmic DNA methyltransferase, ModA, that regulates expression of multiple genes; a phasevarion (phase-variable regulon). Multiple modA alleles are present in NTHi, in which different alleles methylate a different DNA target, and each controls a different set of genes. However, the role of ModA phasevarions in regulating adherence of NTHi to the host airway is not well understood. This study therefore sought to investigate the role of four of the most prevalent ModA phasevarions in the regulation of adherence of NTHi to multiple substrates of the airway. Four clinical isolates of NTHi with unique modA alleles were tested in this study. The adherence of NTHi to mucus, middle ear epithelial cells, and vitronectin was regulated in a substrate-specific manner that was dependent on the ModA allele encoded. The adhesins Protein E and P4 were found to contribute to the ModA-regulated adherence of NTHi to distinct substrates. A better understanding of substrate-specific regulation of NTHi adherence by ModA phasevarions will allow identification of NTHi populations present at the site of disease within the airway and facilitate more directed development of vaccines and therapeutics. IMPORTANCE Nontypeable Haemophilus influenzae (NTHi) is a predominant pathogen of the human airway that causes respiratory infections such as otitis media (OM) and exacerbations in the lungs of patients suffering from chronic obstructive pulmonary disease (COPD). Due to the lack of a licensed vaccine against NTHi and the emergence of antibiotic-resistant strains, it is extremely challenging to target NTHi for treatment. NTHi adhesins are considered potential candidates for vaccines or other therapeutic approaches. The ModA phasevarions of NTHi play a role in the rapid adaptation of the pathogen to different environmental stress conditions. This study addressed the role of ModA phasevarions in the regulation of adherence of NTHi to specific host substrates found within the respiratory tract. The findings of this study improve our understanding of regulation of adherence of NTHi to the airway, which may further be used to enhance the potential of adhesins as vaccine antigens and therapeutic targets against NTHi.

Pathogens associated with hospitalization due to acute lower respiratory tract infections in children in rural Ghana: a case-control study

Respiratory infections are one of the most common causes of death among children under the age of five years. Data on prevalence and relevance of specific organisms in African children are still lacking. This case-control-study investigated prevalence and relevance of specific organisms in Ghanaian children admitted to hospital with symptoms of lower respiratory tract infection (LRTI). Pharyngeal swabs were taken and tested by PCR for 19 respiratory isolates. Adjusted odds ratios (aORs) were calculated to estimate associations between isolates and admission with LRTI. Population attributable fractions (PAFs) were calculated to assess the proportion of LRTI cases due to a particular pathogen. The study included 327 cases and 562 controls. We found associations between detection and admission for LRTI for influenza (aOR 98.6; 95% confidence interval (CI) 20.0-1789.6), respiratory syncytial virus (aOR 40.2; 95% CI 7.2-758.6), H. influenzae (aOR 4.1; 95% CI 2.2-7.9) and S. pneumoniae (aOR 2.4; 95% CI 1.7-3.4). PAFs ≥ 10% were observed for S. pneumoniae (30%; 95% CI 26-42), H. influenzae (10%; 95% CI 2-19) and influenza (10%; 95% CI 2-18). This study highlights the need for heightened surveillance and development of effective vaccines for respiratory pathogens other than SARS-CoV-2 in the future.

Haemophilus influenzae carriage and antibiotic resistance profile in Belgian infants over a three-year period (2016-2018)

Background

Non-typeable Haemophilus influenzae has become increasingly important as a causative agent of invasive diseases following vaccination against H. influenzae type b. The emergence of antibiotic resistance underscores the necessity to investigate typeable non-b carriage and non-typeable H. influenzae (NTHi) in children.

Methods

Nasopharyngeal swab samples were taken over a three-year period (2016-2018) from 336 children (6-30 months of age) attending daycare centers (DCCs) in Belgium, and from 218 children with acute otitis media (AOM). Biotype, serotype, and antibiotic resistance of H. influenzae strains were determined phenotypically. Mutations in the ftsI gene were explored in 129 strains that were resistant or had reduced susceptibility to beta-lactam antibiotics. Results were compared with data obtained during overlapping time periods from 94 children experiencing invasive disease.

Results

Overall, NTHi was most frequently present in both carriage (DCC, AOM) and invasive group. This was followed by serotype "f" (2.2%) and "e" (1.4%) in carriage, and "b" (16.0%), "f" (11.7%), and "a" (4.3%) in invasive strains. Biotype II was most prevalent in all studied groups, followed by biotype III in carriage and I in invasive strains. Strains from both groups showed highest resistance to ampicillin (26.7% in carriage vs. 18.1% in invasive group). A higher frequency of ftsI mutations were found in the AOM group than the DCC group (21.6 vs. 14.9% - p = 0.056). Even more so, the proportion of biotype III strains that carried a ftsI mutation was higher in AOM compared to DCC (50.0 vs. 26.3% - p < 0.01) and invasive group.

Conclusion

In both groups, NTHi was most frequently circulating, while specific encapsulated serotypes for carriage and invasive group were found. Biotypes I, II and III were more frequently present in the carriage and invasive group. The carriage group had a higher resistance-frequency to the analyzed antibiotics than the invasive group. Interestingly, a higher degree of ftsI mutations was found in children with AOM compared to DCC and invasive group. This data helps understanding the H. influenzae carriage in Belgian children, as such information is scarce.

Evidence of maternal transfer of antigen-specific antibodies in serum and breast milk to infants at high-risk of S. pneumoniae and H. influenzae disease

Introduction

Children in low-mid income countries, and First Nations children in high-income countries, experience disproportionately high rates of Streptococcus pneumoniae and Haemophilus influenzae infections and diseases including pneumonia and otitis media. We previously observed that infants from Papua New Guinea had no evidence of waning maternal immunity for H. influenzae-specific antibodies. In this study, we assessed S. pneumoniae and H. influenzae antibody titres in Australian First Nation mothers and infants to determine antigen-specific antibody ontogenies and whether H. influenzae antibody titres in infants were due to low maternal antibody titres or lack of placental transfer.

Methods

Breast milk, infant nasopharyngeal swabs and ear assessment data were collected 1-, 2-, 7-months post-birth as well as maternal, cord and 7-month-old infant sera, from 85 Australian Aboriginal and Torres Strait Islander mother-infant pairs. Serum IgG and breast milk IgG and IgA antibody titres to S. pneumoniae antigens (PspA1, PspA2, CbpA, Ply) and H. influenzae antigens (PD, ChimV4, OMP26, rsPilA) were measured.

Results

IgG titres in maternal and cord sera were similar for all antigens, except Ply (higher in cord; p=0.004). Sera IgG titres at 7-months of age were lower than cord sera IgG titres for all S. pneumoniae antigens (p<0.001). Infant sera IgG titres were higher than cord sera for H. influenzae PD (p=0.029), similar for OMP26 (p=0.817) and rsPilA (p=0.290), and lower for ChimV4 (p=0.004). Breast milk titres were similar for all antigens at 1, 2 and 7-months except OMP26 IgA (lower at 7-months than 1-month; p=0.035), PspA2 IgG (p=0.012) and Ply IgG that increased by 7-months (p=0.032). One third of infants carried nontypeable Haemophilus influenzae (NTHi), 45% carried S. pneumoniae and 52% had otitis media (OM) observed at least once over the 7-months. 73% of infants who carried either S. pneumoniae or NTHi, also had otitis media observed.

Conclusions

Similarities between maternal and cord IgG titres, and absence of waning, support a lack of maternal H. influenzae IgG antibodies available for cross-placental transfer. Increased maternal anti-PD IgG could offer some protection from early carriage with NTHi, and maternal immunisation strategies should be considered for passive-active immunisation of infants to protect against S. pneumoniae and H. influenzae diseases.

Trial registration

ClinicalTrials.gov NCT00714064 and NCT00310349.

The association between bacteria colonizing the upper respiratory tract and lower respiratory tract infection in young children: a systematic review and meta-analysis

BACKGROUND

Bacteria colonizing the upper respiratory tract (URT) of young children play a key role in the pathogenesis of lower respiratory tract infection (LRTI).

OBJECTIVES

To systematically review the literature on the association between bacteria colonizing the URT and LRTI among young children.

DATA SOURCES

MEDLINE, Academic Search Premier, Africa-Wide Information and CINAHL, Scopus and Web of Science.

STUDY ELIGIBILITY CRITERIA

Studies published between 1923 and 2020, investigating URT bacteria from LRTI cases and controls.

PARTICIPANTS

Children under 5 years with and without acute LRTI.

METHODS

Three reviewers independently screened titles, abstracts and full texts. Meta-analysis was done using Mantel-Haenszel fixed- or random-effects models.

RESULTS

Most eligible studies (41/50) tested nasopharyngeal specimens when investigating URT bacteria. Most studies were of cross-sectional design (44/50). Twenty-four studies were performed in children in lower- or lower-middle-income countries (LMICs). There was higher prevalence of Haemophilus influenzae (pooled OR 1.60; 95% CI 1.23-2.07) and Klebsiella spp. (pooled OR 2.04; 95% CI 1.17-3.55) from URT specimens of cases versus controls. We observed a positive association between the detection of Streptococcus pneumoniae from URT specimens and LRTI after excluding studies where there was more antibiotic treatment prior to sampling in cases vs. controls (pooled OR 1.41; 95% CI 1.04-1.90). High density colonization with S. pneumoniae (>6.9 log10 copies/mL) was associated with an increased risk for LRTI. The associations between both Streptococcus and Haemophilus URT detection and LRTI were supported, at genus level, by 16S rRNA sequencing. Evidence for the role of Moraxella catarrhalis and Staphylococcus aureus was inconclusive.

CONCLUSIONS

Detection of H. influenzae or Klebsiella spp. in the URT was associated with LRTI, while evidence for association with S. pneumoniae was less conclusive. Longitudinal studies assessing URT microbial communities, together with environmental and host factors are needed to better understand pathogenesis of childhood LRTI.

Differences in Pneumococcal and Haemophilus influenzae Natural Antibody Development in Papua New Guinean Children in the First Year of Life

Background

Development of vaccines to prevent disease and death from Streptococcus pneumoniae, and nontypeable Haemophilus influenzae (NTHi), the main pathogens that cause otitis media, pneumonia, meningitis and sepsis, are a global priority. Children living in low and lower-middle income settings are at the highest risk of contracting and dying from these diseases. Improved vaccines with broader coverage are required. Data on the natural development of antibodies to putative vaccine antigens, especially in high-risk settings, can inform the rational selection of the best antigens for vaccine development.

Methods

Serum IgG titres to four pneumococcal proteins (PspA1, PspA2, CbpA, and Ply) and five NTHi antigens (P4, P6, OMP26, rsPilA and ChimV4) were measured in sera collected from 101 Papua New Guinean children at 1, 4, 9, 10, 23 and 24 months of age using multiplexed bead-based immunoassays. Carriage density of S. pneumoniae and H. influenzae were assessed by quantitative PCR on genomic DNA extracted from nasopharyngeal swabs using species-specific primers and probes. All data were log-transformed for analysis using Student’s unpaired t-tests with geometric mean titre (GMT) or density (GMD) calculated with 95% confidence intervals (CI).

Results

Serum -pneumococcal protein-specific IgG titres followed a “U” shaped pattern, with a decrease in presumably maternally-derived IgG titres between 1 and 4 months of age and returning to similar levels as those measured at 1 month of age by 24 months of age. In contrast, NTHi protein-specific IgG titres steadily increased with age. There was no correlation between antibody titres and carriage density for either pathogen.

Conclusion

This longitudinal study indicates that the waning of maternally- derived antibodies that is usually observed in infants, after infants does not occur for NTHi antigens in Papua New Guinean infants. Whether NTHi antigen IgG can be transferred maternally remains to be determined. Vaccines that are designed to specifically increase the presence of protective NTHi antibodies in the first few months of life may be most effective in reducing NTHi disease.

Clinical Trial Registration

https://clinicaltrials.gov/, identifier NCT01619462.

The Role of Non-Typeable Haemophilus influenzae Biofilms in Chronic Obstructive Pulmonary Disease

Non-typeable Haemophilus influenzae (NTHi) is an ubiquitous commensal-turned-pathogen that colonises the respiratory mucosa in airways diseases including Chronic Obstructive Pulmonary Disease (COPD). COPD is a progressive inflammatory syndrome of the lungs, encompassing chronic bronchitis that is characterised by mucus hypersecretion and impaired mucociliary clearance and creates a static, protective, humid, and nutrient-rich environment, with dysregulated mucosal immunity; a favourable environment for NTHi colonisation. Several recent large COPD cohort studies have reported NTHi as a significant and recurrent aetiological pathogen in acute exacerbations of COPD. NTHi proliferation has been associated with increased hospitalisation, disease severity, morbidity and significant lung microbiome shifts. However, some cohorts with patients at different severities of COPD do not report that NTHi is a significant aetiological pathogen in their COPD patients, indicating other obligate pathogens including Moraxella catarrhalis, Streptococcus pneumoniae and Pseudomonas aeruginosa as the cause. NTHi is an ubiquitous organism across healthy non-smokers, healthy smokers and COPD patients from childhood to adulthood, but it currently remains unclear why NTHi becomes pathogenic in only some cohorts of COPD patients, and what behaviours, interactions and adaptations are driving this susceptibility. There is emerging evidence that biofilm-phase NTHi may play a significant role in COPD. NTHi displays many hallmarks of the biofilm lifestyle and expresses key biofilm formation-promoting genes. These include the autoinducer-mediated quorum sensing system, epithelial- and mucus-binding adhesins and expression of a protective, self-produced polymeric substance matrix. These NTHi biofilms exhibit extreme tolerance to antimicrobial treatments and the immune system as well as expressing synergistic interspecific interactions with other lung pathogens including S. pneumoniae and M. catarrhalis. Whilst the majority of our understanding surrounding NTHi as a biofilm arises from otitis media or in-vitro bacterial monoculture models, the role of NTHi biofilms in the COPD lung is now being studied. This review explores the evidence for the existence of NTHi biofilms and their impact in the COPD lung. Understanding the nature of chronic and recurrent NTHi infections in acute exacerbations of COPD could have important implications for clinical treatment and identification of novel bactericidal targets.

PCV10 elicits Protein D IgG responses in Papua New Guinean children but has no impact on NTHi carriage in the first two years of life

BACKGROUND

Nasopharyngeal colonisation with nontypeable Haemophilus influenzae (NTHi) is associated with development of infections including pneumonia and otitis media. The 10-valent pneumococcal conjugate vaccine (PCV10) uses NTHi Protein D (PD) as a carrier. Papua New Guinean children have exceptionally early and dense NTHi carriage, and high rates of NTHi-associated disease. Vaccination with PCV10 could potentially reduce NTHi carriage and disease in this population by inducing a NTHi PD immune response.

METHODS

Serum and nasopharyngeal swabs were collected from 101 Papua New Guinean children at 1, 4, 9, 10, 23 and 24 months of age. Children received PCV10 (n = 55) or PCV13 (not containing NTHi PD) (n = 46) at 1, 2 and 3 months of age. NTHi carriage density was measured in swabs by qPCR. Serum PD-IgG levels were measured by bead-based immunoassay.

RESULTS

Papua New Guinean children did naturally develop PD-IgG antibodies whose levels were increased at 4 months of age with PCV10 vaccination at 1-2-3 months. Despite this, most children were colonised with NTHi by 4 months of age (~95%) regardless of being vaccinated with PCV10 or PCV13, and PCV10 had no impact on NTHi carriage density.

CONCLUSION

Early vaccination of infants with PCV10 elicited a robust PD antibody response but this had no impact on NTHi carriage.

TRIAL REGISTRATION

ClinicalTrials.gov CTN NCT01619462.

Characteristics and Antibiotic Resistance of Haemophilus influenzae in Children with Lower Respiratory Tract Infection in Chengdu, China

Background: Haemophilus influenzae is an opportunistic pathogen of the human respiratory tract. Haemophilus influenzae can cause not only respiratory tract infection in children but also otitis media, epiglottitis and sinusitis. With the widespread use of antibiotics, the positive rate of β-lactamase in H. influenzae is increasing, and the rate of antimicrobial resistance is also increasing, which increases the difficulty of clinical treatment. Objectives: To study the infection characteristics of patients and the antibiotic resistance of H. influenzae in lower respiratory tract samples of children in Chengdu, so as to provide a reference for its clinical diagnosis and the rational use of antibiotics. Methods: Sputum samples of 15891 children aged 0-14 years with lower respiratory tract infection were collected. Haemophilus influenzae was cultured and identified, its drug susceptibility tested, and the results determined according to the guidelines of CLSI 2020. Results: A total of 15891 clinical isolate strains in sputum were detected for drug sensitivity from December 2018 to January 2020, of which 5488 were H. influenzae, accounting for 34.54% (5488/15891). The sex of children infected with H. influenzae was not skewed (P > 0.05). The detection rate of H. influenzae was the highest in children aged 7 - 11 months, and the lowest was in the age group ≤ 28 d. The detection rate was the highest in spring and the lowest in autumn. The positive rate of β-lactamase was 92.0%, the resistance rate to ampicillin was 92.0%, the sensitivity to amoxicillin/clavulanate was 70.2%, and the sensitivity to cefotaxime, ofloxacin, tetracycline, chloramphenicol, and rifampicin was more than 90.0%. Conclusions: Children aged 7 months to 14 years were generally susceptible to H. influenzae in spring, and the positive rate of β-lactamase was high. Doctors should refer to the infection characteristics and drug resistance of H. influenzae and choose antibiotics correctly to better control the infection.

Viral-bacterial (co-)occurrence in the upper airways and the risk of childhood pneumonia in resource-limited settings

OBJECTIVE

To examine the association between bacterial-viral co-occurrence in the nasopharynx and the risk of community acquired pneumonia (CAP) in young children living in resource-limited settings.

METHODS

A case-control study was conducted between January and December 2017 in Moshi, Tanzania. Children 2-59 months with CAP and healthy controls were enrolled. RSV and Influenza A/B were detected with a standardized polymerase chain reaction (PCR) method, and a simplified real-time quantitative PCR method, without sample pre-processing, was developed to detect bacterial pathogens in nasopharyngeal samples.

RESULTS

A total of 109 CAP patients and 324 healthy controls were enrolled. Co-detection of H. influenzae and S. pneumoniae in nasopharyngeal swabs was linked with higher odds of CAP (aOR=3.2, 95% CI=1.1-9.5). The majority of the H. influenzae isolated in cases and controls (95.8%) were non-typeable. Of the viruses examined, respiratory syncytial virus (RSV) was most common (n = 31, 7.2%) in cases and controls. Children with RSV had 8.4 times higher odds to develop pneumonia than healthy children (aOR=8.4, 95%CI= 3.2 - 22.1).

CONCLUSIONS

Co-occurence of H. influenzae and S. pneumoniae in the nasopharynx was strongly associated with CAP. The high prevalence of non-typeable H. influenzae might be a sign of replacement as a consequence of Haemophilus influenzae type b vaccination.

Extensively drug-resistant Haemophilus influenzae - emergence, epidemiology, risk factors, and regimen

Background

Concern about Haemophilus influenzae infection has been increasing over recent decades. Given the emergence of H. influenzae with severe drug resistance, we assessed the prevalence of as well as risk factors and potential therapies for extensively drug-resistant (XDR) H. influenzae infection in Taiwan.

Results

In total, 2091 H. influenzae isolates with disk diffusion-based antibiotic susceptibility testing from 2007 to 2018 were enrolled. H. influenzae strains resistant to ampicillin, chloramphenicol, levofloxacin, and trimethoprim-sulfamethoxazole tended to be isolated from patient wards (≧41%), whereas those resistant to amoxicillin-clavulanate, cefotaxime, and cefuroxime were more likely to be isolated from intensive care units (approximately 50%). XDR H. influenzae was first identified in 2007, and its incidence did not significantly change thereafter. Overall prevalence of single, multiple, and extensively drug-resistant H. influenzae over 2007–2018 was 21.5% (n = 450), 26.6% (n = 557), and 2.5% (n = 52), respectively. A stepwise logistic regression analysis revealed that blood culture (odds ratio: 4.069, 95% confidence intervals: 1.339–12.365, P = 0.013) was an independent risk factor for XDR H. influenzae infection. No nosocomial transmission of XDR H. influenzae observed. Antibiotic susceptibility testing results demonstrated that cefotaxime was effective against 78.8% (n = 41) of the XDR strains.

Conclusions

The presence of XDR H. influenzae strains was identified in Taiwan, and cefotaxime was efficacious against most of these strains.

Nasal Delivery of a Commensal Pasteurellaceae Species Inhibits Nontypeable Haemophilus influenzae Colonization and Delays Onset of Otitis Media in Mice

Nasopharyngeal colonization with nontypeable Haemophilus influenzae (NTHi) is a prerequisite for developing NTHi-associated infections, including otitis media. Therapies that block NTHi colonization may prevent disease development. We previously demonstrated that Haemophilus haemolyticus, a closely related human commensal, can inhibit NTHi colonization and infection of human respiratory epithelium in vitro. We have now assessed whether Muribacter muris (a rodent commensal from the same family) can prevent NTHi colonization and disease in vivo using a murine NTHi otitis media model.

Nasopharyngeal colonization with nontypeable Haemophilus influenzae (NTHi) is a prerequisite for developing NTHi-associated infections, including otitis media. Therapies that block NTHi colonization may prevent disease development. We previously demonstrated that Haemophilus haemolyticus, a closely related human commensal, can inhibit NTHi colonization and infection of human respiratory epithelium in vitro. We have now assessed whether Muribacter muris (a rodent commensal from the same family) can prevent NTHi colonization and disease in vivo using a murine NTHi otitis media model. Otitis media was modeled in BALB/c mice using coinfection with 1 × 10^4.5 PFU of influenza A virus MEM H3N2, followed by intranasal challenge with 5 × 10⁷ CFU of NTHi R2866 Spec^r. Mice were pretreated or not with an intranasal inoculation of 5 × 10⁷ CFU M. muris 24 h before coinfection. NTHi and M. muris viable counts and inflammatory mediators (gamma interferon [IFN-γ], interleukin-1β [IL-1β], IL-6, keratinocyte chemoattractant [KC], and IL-10) were measured in nasal washes and middle ear tissue homogenate. M. muris pretreatment decreased the median colonization density of NTHi from 6 × 10⁵ CFU/ml to 9 × 10³ CFU/ml (P = 0.0004). Only 1/12 M. muris-pretreated mice developed otitis media on day 5 compared to 8/15 mice with no pretreatment (8% versus 53%, P = 0.0192). Inflammation, clinical score, and weight loss were also lower in M. muris-pretreated mice. We have demonstrated that a single dose of a closely related commensal can delay onset of NTHi otitis media in vivo. Human challenge studies investigating prevention of NTHi colonization are warranted to reduce the global burden of otitis media and other NTHi diseases.

Bacterial pneumonia and its associated factors in children from a developing country: A prospective cohort study

Introduction

Pneumonia in children is a common disease yet determining its aetiology remains elusive.

Objectives

To determine the a) aetiology, b) factors associated with bacterial pneumonia and c) association between co-infections (bacteria + virus) and severity of disease, in children admitted with severe pneumonia.

Methods

A prospective cohort study involving children aged 1-month to 5-years admitted with very severe pneumonia, as per the WHO definition, over 2 years. Induced sputum and blood obtained within 24 hrs of admission were examined via PCR, immunofluorescence and culture to detect 17 bacteria/viruses. A designated radiologist read the chest radiographs.

Results

Three hundred patients with a mean (SD) age of 14 (±15) months old were recruited. Significant pathogens were detected in 62% of patients (n = 186). Viruses alone were detected in 23.7% (n = 71) with rhinovirus (31%), human metapneumovirus (HMP) [22.5%] and respiratory syncytial virus (RSV) [16.9%] being the commonest. Bacteria alone was detected in 25% (n = 75) with Haemophilus influenzae (29.3%), Staphylococcus aureus (24%) and Streptococcus pneumoniae (22.7%) being the commonest. Co-infections were seen in 13.3% (n = 40) of patients. Male gender (AdjOR 1.84 [95% CI 1.10, 3.05]) and presence of crepitations (AdjOR 2.27 [95% CI 1.12, 4.60]) were associated with bacterial infection. C-reactive protein (CRP) [p = 0.007]) was significantly higher in patients with co-infections but duration of hospitalization (p = 0.77) and requirement for supplemental respiratory support (p = 0.26) were not associated with co-infection.

Conclusions

Bacteria remain an important cause of very severe pneumonia in developing countries with one in four children admitted isolating bacteria alone. Male gender and presence of crepitations were significantly associated with bacterial aetiology. Co-infection was associated with a higher CRP but no other parameters of severe clinical illness.

Severe Presentation of Nontypeable Haemophilus influenzae (NTHi) Infection in a Previously Healthy Toddler

Background

Cellulitis is the inflammation of the skin and subcutaneous tissue. It is usually caused by Gram-positive organisms such as Staphylococcus and Streptococcus pyogenes infection. Nontypeable Haemophilus influenzae (NTHi) is an uncommon cause of cellulitis. Hence, we report on this case.

Case Presentation

A previously healthy 19-month-old girl presented with a fever and two-day history of progressive right leg swelling and redness. Her physical examination revealed significant induration and swelling of her right lower leg but no obvious signs of abscess formation. Given the clinical picture, she was admitted as a case of cellulitis. Parenteral clindamycin was started empirically, as the blood culture preliminary report showed Gram-negative rods. Ceftriaxone was added to broaden the coverage. Final blood culture grew NTHi. Despite the use of proper antibiotics (amoxicillin clavulanic acid), the clinical course was complicated with abscess formation that required surgical intervention.

Conclusions

We are reporting a previously healthy child who developed NTHi cellulitis of the lower leg. To the best of our knowledge, there have been no formal reports pertaining to leg cellulitis following infection by NTHi, yet published in UAE, and reports of HIB cellulitis of the extremities still appear to be rare; hence, we report on this case.

Molecular Signatures of Non-typeable Haemophilus influenzae Lung Adaptation in Pediatric Chronic Lung Disease

Non-typeable Haemophilus influenzae (NTHi), an opportunistic pathogen of the upper airways of healthy children, can infect the lower airways, driving chronic lung disease. However, the molecular basis underpinning NTHi transition from a commensal to a pathogen is not clearly understood. Here, we performed comparative genomic and transcriptomic analyses of 12 paired, isogenic NTHi strains, isolated from the nasopharynx (NP) and bronchoalveolar lavage (BAL) of 11 children with chronic lung disease, to identify convergent molecular signatures associated with lung adaptation. Comparative genomic analyses of the 12 NP-BAL pairs demonstrated that five were genetically identical, with the remaining seven differing by only 1 to 3 mutations. Within-patient transcriptomic analyses identified between 2 and 58 differentially expressed genes in 8 of the 12 NP-BAL pairs, including pairs with no observable genomic changes. Whilst no convergence was observed at the gene level, functional enrichment analysis revealed significant under-representation of differentially expressed genes belonging to Coenzyme metabolism, Function unknown, Translation, ribosomal structure, and biogenesis Cluster of Orthologous Groups categories. In contrast, Carbohydrate transport and metabolism, Cell motility and secretion, Intracellular trafficking and secretion, and Energy production categories were over-represented. This observed trend amongst genetically unrelated NTHi strains provides evidence of convergent transcriptional adaptation of NTHi to pediatric airways that deserves further exploration. Understanding the pathoadaptative mechanisms that NTHi employs to infect and persist in the lower pediatric airways is essential for devising targeted diagnostics and treatments aimed at minimizing disease severity, and ultimately, preventing NTHi lung infections and subsequent chronic lung disease in children.

The Interplay Between Immune Response and Bacterial Infection in COPD: Focus Upon Non-typeable Haemophilus influenzae

Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by non-typeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a "vicious circle." Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.

Insights into the population structure and pan-genome of Haemophilus influenzae

The human-restricted bacterium Haemophilus influenzae is responsible for respiratory infections in both children and adults. While colonization begins in the upper airways, it can spread throughout the respiratory tract potentially leading to invasive infections. Although the spread of H. influenzae serotype b (Hib) has been prevented by vaccination, the emergence of infections by other serotypes as well as by non-typeable isolates (NTHi) have been observed, prompting the need for novel prevention strategies. Here, we aimed to study the population structure of H. influenzae and to get some insights into its pan-genome. We studied 305H. influenzae strains, enrolling 217 publicly available genomes, as well as 88 newly sequenced H. influenzae invasive strains isolated in Portugal, spanning a 24-year period. NTHi isolates presented a core-SNP-based genetic diversity about 10-fold higher than the one observed for Hib. The analysis of key factors involved in pathogenesis, such as lipooligosaccharides, hemagglutinating pili and High Molecular Weight-adhesins, suggests that NTHi shape its virulence repertoire, either by acquisition and loss of genes or by SNP-based diversification, likely towards host immune evasion and persistence. Discreet NTHi subpopulations structures are proposed based on core-genome supported with 17 candidate genetic markers identified in the accessory genome. Additionally, this study provides two bioinformatics tools for in silico rapid identification of H. influenzae serotypes and NTHi clades previously proposed, obviating laboratory-based demanding procedures. The present study constitutes an important genomic framework that could lay way for future studies on the genetic determinants underlying invasiveness and disease and population structure of H. influenzae.

Pneumococcal vaccine impacts on the population genomics of non-typeable Haemophilus influenzae

The implementation of pneumococcal conjugate vaccines (PCVs) has led to a decline in vaccine-type disease. However, there is evidence that the epidemiology of non-typeable Haemophilus influenzae (NTHi) carriage and disease can be altered as a consequence of PCV introduction. We explored the epidemiological shifts in NTHi carriage using whole genome sequencing over a 5-year period that included PCV13 replacement of PCV7 in the UK’s National Immunization Programme in 2010. Between 2008/09 and 2012/13 (October to March), nasopharyngeal swabs were taken from children <5 years of age. Significantly increased carriage post-PCV13 was observed and lineage-specific associations with Streptococcus pneumoniae were seen before but not after PCV13 introduction. NTHi were characterized into 11 discrete, temporally stable lineages, congruent with current knowledge regarding the clonality of NTHi. The increased carriage could not be linked to the expansion of a particular clone and different co-carriage dynamics were seen before PCV13 implementation when NTHi co-carried with vaccine serotype pneumococci. In summary, PCV13 introduction has been shown to have an indirect effect on NTHi epidemiology and there exists both negative and positive, distinct associations between pneumococci and NTHi. This should be considered when evaluating the impacts of pneumococcal vaccine design and policy.