Invasive disease caused by Haemophilus influenzae in Sweden 1997-2009; evidence of increasing incidence and clinical burden of non-type b strains

Increase in invasive Haemophilus influenzae serotype A infections during the COVID-19 pandemic in New South Wales, Australia

Haemophilus influenzae, a causative agent of severe invasive infections such as meningitis, sepsis and pneumonia, is classified into encapsulated or typeable (represented by serotypes A to F) and non-typeable varieties (NTHi) by the presence or absence of the polysaccharide capsule. Invasive disease caused by H. influenzae type B (HIB) can be prevented through vaccination which remains the main disease control intervention in many countries. This study examined the genomic diversity of circulating H. influenzae strains associated with invasive disease in New South Wales, Australia, before and during the COVID-19 pandemic. Ninety-six isolates representing 95 cases of invasive H. influenzae infections (iHi) diagnosed between January 2017 and September 2022 were typed and characterised using whole genome sequencing. These cases were caused by serotypes A (n=24), B (n=35), E (n=3), F (n=2) and NTHi (n=32). There was an apparent decline in the number of iHi infections during the COVID-19 pandemic, with a corresponding increase in the proportion of iHi cases caused by serotype A (HIA), which returned to pre-pandemic levels in 2022. Fifteen isolates associated with HIB or non-typeable iHi were resistant to β-lactams due to a PBP3 mutation or carriage of blaTEM-1. Further, capsular gene duplication was observed in HIB isolates but was not found in HIA. These findings provide important baseline genomic data for ongoing iHi surveillance and control.

High Prevalence of Non-typeable Haemophilus influenzae and Haemophilus haemolyticus Among Vaccinated Children with Community-Acquired Pneumonia in Vietnam

Among 467 children under five hospitalized with community-acquired pneumonia, the prevalence of Haemophilus influenzae or Haemophilus haemolyticus was 60.8%, all cases were non-typable H. influenzae (NTHi) or H. haemolyticus. NTHi/H. haemolyticus PCR detection was associated with about twice the risk for severe disease. The results highlight the need for increased awareness and research efforts to investigate the role of NTHi/H. haemolyticus in severe CAP among children.

Synthesis of Pseudooligosaccharides Related to the Capsular Phosphoglycan of Haemophilus influenzae Type a

Synthesis of spacer-armed pseudodi-, pseudotetra-, and pseudohexasaccharides related to the capsular phosphoglycan of Haemophilus influenzae type a, the second most virulent serotype of H. influenzae (after type b), was performed for the first time via iterative chain elongation using H-phosphonate chemistry for the formation of inter-unit phosphodiester bridges. These compounds were prepared for the design of neoglycoconjugates, as exemplified by the transformation of the obtained pseudohexasaccharide derivative into a biotinylated glycoconjugate suitable for use in immunological studies, particularly in diagnostic screening systems as a coating antigen for streptavidin-coated plates and chip slides.

Non-typeable Haemophilus influenza ventriculitis, a case report and literature review

Introduction

and importance: Haemophilus influenza severe presentations have decreased dramatically after the Hib vaccination was introduced. However, due to the emergence of Multi-drug resistance organisms, severe presentations like meningitis and ventriculitis may occur.

Case presentation

Here, we have described a rarely reported case of non-typeable Haemophilus influenza ventriculitis in a previously healthy patient. MRI of the head with contrast was suggestive of tiny foci of diffusion restriction in occipital horns of bilateral ventricles with minimal intraventricular pus formation. The diagnosis was confirmed based on blood culture results and MRI findings as the patient refused to have a lumbar puncture procedure for CSF analysis. The patient was treated with intravenous antibiotics and showed a good response.

Clinical discussion

In the post-HiB immunization era, we have seen a decline in invasive diseases caused by Type B Haemophilus influenza. However, non-typeable Haemophilus influenzae is now on the rise. Central nervous system infection due to non-typable Haemophilus influenza is infrequent as this organism is predominantly a respiratory mucosal pathogen resulting in acute and chronic respiratory tract infections. Multi-drug resistance of non-typeable Haemophilus influenzae is also becoming a cause of concern.

Conclusion

Ventriculitis secondary to non-typeable beta-lactamase non-producing, ampicillin-resistant (BLNAR) Haemophilus influenza is rare, and more such cases need to be reported within the adult population to avoid under-recognition.

Molecular epidemiology and antibiotic resistance profiles of invasive Haemophilus influenzae from Norway 2017–2021

Invasive Haemophilus influenzae (Hi) disease has decreased in countries that included Hi type b (Hib) vaccination in their childhood immunization programs in the 1990s. Non-typeable (NT) and non-b strains are now the leading causes of invasive Hi disease in Europe, with most cases reported in young children and the elderly. Concerningly, no vaccines toward such strains are available and beta-lactam resistance is increasing. We describe the epidemiology of invasive Hi disease reported to the Norwegian Surveillance System for Communicable Diseases (MSIS) (2017–2021, n = 407). Whole-genome sequencing (WGS) was performed on 245 isolates. We investigated the molecular epidemiology (core genome phylogeny) and the presence of antibiotic resistance markers (including chromosomal mutations associated with beta-lactam or quinolone resistance). For isolates characterized with both WGS and phenotypic antibiotic susceptibility testing (AST) (n = 113) we assessed correlation between resistance markers and susceptibility categorization by calculation of sensitivity, specificity, and predictive values. Incidence rates of invasive Hi disease in Norway ranged from 0.7 to 2.3 per 100,000 inhabitants/year (mean 1.5 per 100,000) and declined during the COVID-19 pandemic. The bacterial population consisted of two major phylogenetic groups with subclustering by serotype and multi-locus sequence type (ST). NTHi accounted for 71.8% (176). The distribution of STs was in line with previous European reports. We identified 13 clusters, including four encapsulated and three previously described international NTHi clones with blaTEM–1 (ST103) or altered PBP3 (rPBP3) (ST14/IIA and ST367/IIA). Resistance markers were detected in 25.3% (62/245) of the isolates, with blaTEM–1 (31, 50.0%) and rPBP3 (28, 45.2%) being the most frequent. All isolates categorized as resistant to aminopenicillins, tetracycline or chloramphenicol possessed relevant resistance markers, and the absence of relevant substitutions in PBP3 and GyrA/ParC predicted susceptibility to cefotaxime, ceftriaxone, meropenem and quinolones. Among the 132 WGS-only isolates, one isolate had PBP3 substitutions associated with resistance to third-generation cephalosporins, and one isolate had GyrA/ParC alterations associated with quinolone resistance. The detection of international virulent and resistant NTHi clones underlines the need for a global molecular surveillance system. WGS is a useful supplement to AST and should be performed on all invasive isolates.

Bacterial meningitis: Aetiology, risk factors, disease trends and severe sequelae during 50 years in Sweden

BACKGROUND

Bacterial meningitis (BM) is a rare but severe infection. Few population-based studies have characterised BM episodes and sequelae over long periods.

METHODS

This was a population-based observational cohort study with national coverage, using data on aetiological pathogens, sex, premorbid conditions, steroid pretreatment, severe sequelae and birth, death and diagnosis dates collected from 10,339 patients with BM reported to the National Board of Health and Welfare in Sweden between 1964 and 2014.

RESULTS

During the 50-year study period, the incidence of BM decreased in young children, but not in the elderly. The most common cause of BM was pneumococci (34%), followed by Haemophilus influenzae (26%), and meningococci (18%), mainly community acquired. Premorbid conditions were found in 20%. After the H. influenzae type b vaccine was introduced in 1993, the BM incidence decreased by 36%. Following pneumococcal conjugated vaccine introduction in 2009, the incidence and 30-day mortality from pneumococcal meningitis decreased by 64% and 100%, respectively, in previously healthy children, and the 30-day mortality decreased by 64% among comorbid adults. The BM incidence in immunosuppressed patients increased by 3% annually post vaccine introduction. The 30-day mortality was 3% in children and 14% in adults, and the rate of severe sequelae was 44%. On average, patients lost 11 years of healthy life due to BM.

CONCLUSION

The introduction of conjugated vaccines into the childhood vaccination program has reduced the incidence of BM in young children, but not in adults. Post vaccine introduction, patients present with more premorbid conditions and other bacterial causes of BM, emphasising the need for a correct diagnosis when treating these infections.

Impact of a Single-Tube PCR Assay for the Detection of Haemophilus influenzae Serotypes a, c, d, e and f on the Epidemiological Surveillance in Greece

Background: The decrease in the rate of meningitis due to Haemophilus influenzae type b after vaccine introduction and a possible change in epidemiology of H. influenzae disease highlights the need for continuous serotype surveillance. Methods: A single-tube multiplex PCR assay for serotyping of H. influenzae was developed and deployed. Results: During 2003−2020, 108 meningitis cases due to H. influenzae were notified; 86 (80%) were confirmed and serotyped by molecular methods. The overall specificity and sensitivity of the assay were estimated (100% PPV and NPV respectively). The overall mean annual reported incidence for H. influenzae was 0.02, while for Hib and non-b meningitis equaled 0.02 and 0.03 per 100 000, respectively. Analysis by age group revealed that H. influenzae peaks in toddlers and children 0−4 years and in adults >45 years old. Among the serotyped cases, 39.8% were identified as Hib, 46.3% as NTHi, and 0.9% and 2.8% as serotypes a (Hia) and f (Hif)) respectively. Conclusions: Low incidence due to Hib was observed while non-typeable H. influenzae (NTHi) and serotypes Hia and Hif seem to emerge. The application of the current assay discloses the ongoing change of invasive H. influenzae disease trends during the Hib post-vaccine era.

Lipidation of Haemophilus influenzae Antigens P6 and OMP26 Improves Immunogenicity and Protection against Nasopharyngeal Colonization and Ear Infection

Nontypeable Haemophilus influenzae (NTHi) causes respiratory infections that lead to high morbidity and mortality worldwide, encouraging development of effective vaccines. To achieve a protective impact on nasopharyngeal (NP) colonization by NTHi, enhanced immunogenicity beyond that achievable with recombinant-protein antigens is likely to be necessary. Adding a lipid moiety to a recombinant protein would enhance immunogenicity through Toll-like receptor 2 signaling of antigen-presenting cells and Th17 cell response in the nasal-associated lymphoid tissue (NALT). We investigated effects of lipidation (L) of recombinant proteins P6 and OMP26 compared to nonlipidated (NL) P6 and OMP26 and as fusion constructs (L-OMP26ϕNL-P6 and L-P6ϕNL-OMP26) in a mouse model. After intraperitoneal or intranasal vaccination, antibody responses were compared and protection from NP colonization and middle ear infection were assessed. L-P6 and L-OMP26 induced approximately 10- to 100-fold-higher IgG antibody levels than NL-P6 and NL-OMP26. Fusion constructs significantly increased IgG antibody to both target proteins, even though only one of the proteins was lipidated. NP colonization and middle ear bullae NTHi density was 1 to 4 logs lower following vaccination with L-P6 and L-OMP26 than with NL-P6 and NL-OMP26. Fusion constructs also resulted in a 1- to 3-log-lower NTHi density following vaccination. NALT cells from mice vaccinated with lipidated protein constructs had higher levels of interleukin-17 (IL-17), IL-22, and CD4⁺ T-cell memory. Passive transfer of sera from L-OMP26ϕNL-P6-vaccinated mice to recipient infant mice reduced NP colonization and ear bulla NTHi density. We conclude that L-P6, L-OMP26, and fusion constructs generate enhanced antibody responses and protection from NP colonization and middle ear infection by NTHi in mice.

Comparative pangenome analysis of capsulated Haemophilus influenzae serotype f highlights their high genomic stability

Haemophilus influenzae is an opportunistic pathogen adapted to the human respiratory tract. Non-typeable H. influenzae are highly heterogeneous, but few studies have analysed the genomic variability of capsulated strains. This study aims to examine the genetic diversity of 37 serotype f isolates from the Netherlands, Portugal, and Spain, and to compare all capsulated genomes available on public databases. Serotype f isolates belonged to CC124 and shared few single nucleotide polymorphisms (SNPs) (n = 10,999), but a high core genome (> 80%). Three main clades were identified by the presence of 75, 60 and 41 exclusive genes for each clade, respectively. Multi-locus sequence type analysis of all capsulated genomes revealed a reduced number of clonal complexes associated with each serotype. Pangenome analysis showed a large pool of genes (n = 6360), many of which were accessory genome (n = 5323). Phylogenetic analysis revealed that serotypes a, b, and f had greater diversity. The total number of SNPs in serotype f was significantly lower than in serotypes a, b, and e (p < 0.0001), indicating low variability within the serotype f clonal complexes. Capsulated H. influenzae are genetically homogeneous, with few lineages in each serotype. Serotype f has high genetic stability regardless of time and country of isolation.

Increased Incidence of Invasive Haemophilus influenzae Disease Driven by Non-Type B Isolates in Ontario, Canada, 2014 to 2018

Haemophilus influenzae can cause serious invasive disease. We report the epidemiology and antimicrobial susceptibility of invasive H. influenzae in Ontario, Canada, from 2014 to 2018 from laboratory-based data. Blood was the most common specimen source (89.5%). Consistent with widespread vaccination against serotype b (Hib), the incidence of Hib in Ontario remained low (0.04 cases per 100,000 population). H. influenzae disease primarily afflicted those <1 and ≥65 years of age. From 2014 to 2018, cases of invasive H. influenzae increased 5.6%, from 1.67 to 2.06 cases per 100,000 population, the majority of which were attributed to a 7.6% increase in the incidence of H. influenzae in those ≥65 years old. H. influenzae disease was primarily caused by nontypeable H. influenzae (NTHi) (74.2%) and, to a much lesser extent, serotype a (Hia) (8.9%) and serotype f (Hif) (10.2%). Serotype-dependent trends in antimicrobial susceptibility were observed. Hia and Hif isolates were predominantly susceptible to all antibiotics tested, while 27.2% of NTHi isolates were nonsusceptible to ampicillin. Resistance to ceftriaxone and meropenem, first-line antibiotics for invasive disease treatment, was nonexistent. The incidence of invasive H. influenzae in Ontario is increasing. The incidence and antimicrobial susceptibility of all serotypes and nontypeable H. influenzae should be monitored. IMPORTANCE H. influenzae can cause serious invasive, life-threatening disease and is considered 1 of 12 priority pathogens by the World Health Organization. Widespread vaccination against H. influenzae serotype b (Hib) has resulted in very low incidence of Hib in Ontario and other regions that have vaccination programs. However, the epidemiology of non-Hib serotypes and nontypeable H. influenzae (NTHi) remains poorly understood. Here, we describe the epidemiology of all invasive H. influenzae isolates (N = 1,338) received by our laboratory over the 5-year period and report on the antimicrobial susceptibility patterns by serotype. Overall, we observed an increase in the incidence of invasive disease over the study period, primarily driven by NTHi. Serotype-dependent trends in antimicrobial susceptibility were also observed. This work contributes to the global understanding of H. influenzae epidemiology and antimicrobial resistance and is additionally important for further vaccine planning initiatives.

Nontypeable Haemophilus influenzae P5 Binds Human C4b-Binding Protein, Promoting Serum Resistance

Exposure of P5 at the surface of NTHi positively correlates with C4BP binding.

C4BP bound to the bacterial surface retains its complement inhibitory capacity.

C4BP binding to P5 is important for NTHi serum resistance.

Nontypeable Haemophilus influenzae (NTHi) is a Gram-negative human pathogen that causes infections mainly in the upper and lower respiratory tract. The bacterium is associated with bronchitis and exacerbations in patients suffering from chronic obstructive pulmonary disease and frequently causes acute otitis media in preschool children. We have previously demonstrated that the binding of C4b binding protein (C4BP) is important for NTHi complement evasion. In this study, we identified outer membrane protein 5 (P5) of NTHi as a novel ligand of C4BP. Importantly, we observed significantly lower C4BP binding and decreased serum resistance in P5-deficient NTHi mutants. Surface expression of recombinant P5 on Escherichia coli conferred C4BP binding and consequently increased serum resistance. Moreover, P5 expression was positively correlated with C4BP binding in a series of clinical isolates. We revealed higher levels of P5 surface expression and consequently more C4BP binding in isolates from the lower respiratory tract of chronic obstructive pulmonary disease patients and tonsil specimens compared with isolates from the upper respiratory tract and the bloodstream (invasive strains). Our results highlight P5 as an important protein for protecting NTHi against complement-mediated killing.

Effect of Haemophilus influenzae Type b and 13-Valent Pneumococcal Conjugate Vaccines on Childhood Pneumonia Hospitalizations and Deaths in Botswana

BACKGROUND

Globally, pneumonia is the leading cause of death among children. Few data exist regarding the effect of Haemophilus influenzae type b (Hib) vaccine and 13-valent pneumococcal conjugate vaccine (PCV-13) on the burden of childhood pneumonia in African settings.

METHODS

We collected data on children aged 1 to 59 months at 3 hospitals in Botswana. Hib vaccine and PCV-13 were introduced in Botswana in November 2010 and July 2012, respectively. We compared pneumonia hospitalizations and deaths prevaccine (January 2009 to October 2010) with postvaccine (January 2013 to December 2017) using seasonally adjusted, interrupted time-series analyses.

RESULTS

We identified 6943 pneumonia hospitalizations and 201 pneumonia deaths. In the prevaccine period, pneumonia hospitalizations and deaths increased by 24% (rate, 1.24; 95% CI, .94-1.64) and 59% (rate, 1.59; 95% CI, .87-2.90) per year, respectively. Vaccine introduction was associated with a 48% (95% CI, 29-62%) decrease in the number of pneumonia hospitalizations and a 50% (95% CI, 1-75%) decrease in the number of pneumonia deaths between the end of the prevaccine period (October 2010) and the beginning of the postvaccine period (January 2013). During the postvaccine period, pneumonia hospitalizations and deaths declined by 6% (rate, .94; 95% CI, .89-.99) and 22% (rate, .78; 95% CI, .67-.92) per year, respectively.

CONCLUSIONS

Pneumonia hospitalizations and deaths among children declined sharply following introduction of Hib vaccine and PCV-13 in Botswana. This effect was sustained for more than 5 years after vaccine introduction, supporting the long-term effectiveness of these vaccines in preventing childhood pneumonia in Botswana.

An Observational Prospective Cohort Study of Incidence and Outcome of Streptococcus pneumoniae and Hemophilus influenzae Infections in Adult Solid Organ Transplant Recipients

BACKGROUND

Streptococcus pneumoniae (S. pneumoniae) and Hemophilus influenzae (H. influenzae) are among the main vaccine-preventable bacterial infections in immunocompromised individuals including solid organ transplant (SOT) recipients. There is a lack of information about incidence and outcomes of these infections in SOT recipients.

METHODS

We determined the incidence of S. pneumoniae and H. influenzae, the related hospitalization, and 30- and 180-days mortality in a large cohort of 1182 adult SOT recipients. We calculated 95% confidence intervals (CI) of incidence rate (IR) using Byar's approximation to the Poisson distribution.

RESULTS

The overall IR of S. pneumoniae and H. influenzae were 1086 (95% CI, 796-1448) and 1293 (95% CI, 974-1687) per 100,000 person-years of follow-up (PYFU), respectively. The IR of invasive infections were 76 (95% CI, 21-202) and 25 (95% CI, 2.3-118) per 100,000 PYFU, respectively. Hospital admission was required in >50%, 30-days mortality was 0, and 180-days mortality was 8.8% and 4.5% after S. pneumoniae and H. influenzae infections, respectively.

CONCLUSIONS

The IR of invasive S. pneumoniae and H. influenzae infections in SOT recipients were much higher than reports from the general population in Denmark. Furthermore, a large proportion of infected SOT recipients were hospitalized. These findings highlight the need for further studies to assess uptake and immunogenicity of vaccines against S. pneumoniae and H. influenzae in SOT recipients.

A rare case of invasive non-typeable Haemophilus influenzae spondylodiscitis and periprosthetic joint infection

A non-typeable Haemophilus influenzae (NTHi) was responsible for an invasive infection including bacteremia, spondylodiscitis with epidural abscess, and periprosthetic hip infection in a 79-year-old woman, triggered by a superinfected ethmo-orbital mucocele. Surgical drainage and antibiotic therapy allowed recovery. PET-scan full cartography of NTHi infection dissemination enabled the discovery of spondylodiscitis. This rare cause of spondylodiscitis and periprosthetic joint infection suggests a complete work-up is unavoidable.

Invasive Haemophilus influenzae Infections after 3 Decades of Hib Protein Conjugate Vaccine Use

Haemophilus influenzae serotype b (Hib) was previously the most common cause of bacterial meningitis and an important etiologic agent of pneumonia in children aged <5 years. Its major virulence factor is the polyribosyl ribitol phosphate (PRP) polysaccharide capsule. In the 1980s, PRP-protein conjugate Hib vaccines were developed and are now included in almost all national immunization programs, achieving a sustained decline in invasive Hib infections. However, invasive Hib disease has not yet been eliminated in countries with low vaccine coverage, and sporadic outbreaks of Hib infection still occur occasionally in countries with high vaccine coverage. Over the past 2 decades, other capsulated serotypes have been recognized increasingly as causing invasive infections. H. influenzae serotype a (Hia) is now a major cause of invasive infection in Indigenous communities of North America, prompting a possible requirement for an Hia conjugate vaccine. H. influenzae serotypes e and f are now more common than serotype b in Europe. Significant year-to-year increases in nontypeable H. influenzae invasive infections have occurred in many regions of the world. Invasive H. influenzae infections are now seen predominantly in patients at the extremes of life and those with underlying comorbidities. This review provides a comprehensive and critical overview of the current global epidemiology of invasive H. influenzae infections in different geographic regions of the world. It discusses those now at risk of invasive Hib disease, describes the emergence of other severe invasive H. influenzae infections, and emphasizes the importance of long-term, comprehensive, clinical and microbiologic surveillance to monitor a vaccine's impact.

Long Term Impact of Conjugate Vaccines on Haemophilus influenzae Meningitis: Narrative Review

H. influenzae serotype b (Hib) used to be the commonest cause of bacterial meningitis in young children. The widespread use of Hib conjugate vaccine has profoundly altered the epidemiology of H. influenzae meningitis. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a National Immunization Program (NIP). Hib meningitis is now uncommon, but meningitis caused by other capsulated serotypes of H. influenzae and non-typeable strains (NTHi) should be considered. H. influenzae serotype a (Hia) has emerged as a significant cause of meningitis in Indigenous children in North America, which may necessitate a Hia conjugate vaccine. Cases of Hie, Hif, and NTHi meningitis are predominantly seen in young children and less common in older age groups. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a NIP.

Haemophilus influenzae Non-type b Infection in an Adult Patient with Systemic Lupus Erythematosus

A 40-year-old man with systemic lupus erythematosus taking consecutive oral corticosteroids developed a high-grade fever and disorder of consciousness following acute rhinitis. Haemophilus influenzae type f (Hif) was found and isolated from the blood and cerebrospinal fluid by culture, leading to a diagnosis of meningitis. The prevalence of H. influenzae type b (Hib) infections has decreased due to routine immunization. As a result, the prevalence of invasive non-Hib, including Hif infection, is increasing as a common H. influenzae infection in children and adults. Physicians should be aware of non-Hib H. influenzae infection, even though the Hib vaccine is widely used in Japan.

Bacterial composition of nasal discharge in children based on highly accurate 16S rRNA gene sequencing analysis

Nasopharyngeal colonization by bacteria is a prerequisite for progression to respiratory disease and an important source of horizontal spread within communities. We aimed to perform quantitative analysis of the bacterial cells and reveal the microbiota of the nasal discharge in children at the species level based on highly accurate 16S rRNA gene sequencing. This study enrolled 40 pediatric patients with rhinorrhea. The bacterial cells in the nasal discharge were counted by epifluorescence microscopic analysis. The microbiota was analyzed by using the 16S rRNA gene clone library sequencing method. We demonstrated that a high abundance (median 2.2 × 10⁷ cells/mL) of bacteria was contained in the nasal discharge of children. Of the 40 samples, 37 (92.5%) were dominated by OTUs corresponding to Haemophilus aegyptius/influenzae, Moraxella catarrhalis/nonliquefaciens, or Streptococcus pneumoniae. These samples showed higher cell abundance and lower alpha diversity than the remaining three samples in which the other bacteria coexisted. In addition, 12 sequences with low homology to type strains were considered as previously unknown bacterial lineages. In conclusion, the nasal discharge of most young children contains a large amount of respiratory pathogens and several unknown bacteria, which could not only cause endogenous infection but also be a source of transmission to others.

Invasive Haemophilus influenzae Infections in Germany After the Introduction of Routine Childhood Immunization, 2001-2016

Background

Haemophilus influenzae (Hi) serotype b (Hib) vaccination was introduced in Germany in 1990. This study presents a comprehensive overview on the burden of invasive Hi infections for 2001–2016, including serotype distribution and ampicillin resistance.

Methods

Nationwide data from statutory disease surveillance (2001–2016) were linked with laboratory surveillance data (2009–2016). Besides descriptive epidemiology, statistical analyses included multiple imputation to estimate secular trends.

Results

In 2001–2016, 4044 invasive Hi infections were reported. The mean incidence was 3.0 per million inhabitants, higher in males (3.2 vs 2.9 in females) and in the age groups <1 year (15.2) and ≥80 years (15.5). Nontypeable Hi (NTHi) caused 81% (n = 1545) of cases in 2009–2016. Of capsulated cases, 69% were serotype f and 17% serotype b. Of Hib cases eligible for vaccination, 10% (3/29) were fully vaccinated. For 2009–2016, significant increasing trends were observed for NTHi and Hif infections in the age groups <5 years and ≥60 years and for ampicillin resistance in NTHi.

Conclusions

This is one of the most comprehensive Hi data analyses since the introduction of Hib vaccines. NTHi and Hif cause an increasing disease burden among elderly patients and infants. Ampicillin resistance in NTHi must be considered in the treatment of invasive Hi infections.

Respiratory Carriage of Haemophilus influenzae Associated with Hib Vaccine in Jordanian Children

Objective Haemophilus influenzae type b (Hib) is the most virulent serotype that colonizes the upper respiratory tract of children. After introducing Hib conjugate vaccine, Hib has become almost entirely replaced by nontypeable H. influenzae (NTHi) strains. This study investigated the incidence of NTHi, which may cause serious sporadic body infections.

Methods A total of 300 nasal and throat swab samples were obtained from children aged 6 to 60 months, who visited outpatient pediatric clinics of Jordan University Hospital and Al-Bashir Hospital, Amman, Jordan. Colonies resembling H. influenzae were tested by conventional laboratory tests including Gram staining and antibiotic susceptibility. The 16S rRNA and bexA (capsulation gene) were amplified from the extracted DNA. Swabs (n = 100) were delivered to the laboratory in transport media. After initial culture, DNA was extracted directly and tested by conventional polymerase chain reaction (PCR) employing actin beta primers for assessing the housekeeping gene, followed by quantitative PCR (qPCR) against Hib-specific primers.

Results A total of 31/300 (10.33%) of H. influenzae isolates were recovered by culture and confirmed by PCR for 16S rRNA; 96.77% (30/31) were NTHi, and only one isolate was Hib. This isolate was confirmed by detection region II of the cap locus of Hib gene by qualitative TaqMan real-time qPCR. Antibiotic resistance among NTHi to ampicillin and erythromycin was 50.0 and 20.0%, respectively.

Conclusion The conjugated Hib vaccine almost eliminated the occurrence of Hib in the upper respiratory tract of the Jordanian children, while NTHi colonization was found in 10% of them.

Odoriferous Therapy: A Review Identifying Essential Oils against Pathogens of the Respiratory Tract

This review explores the body of scientific information available on the antimicrobial properties of essential oils against pathogens responsible for respiratory infections and critically compares this to what is recommended in the Layman's aroma-therapeutic literature. Essential oils are predominantly indicated for the treatment of respiratory infections caused by bacteria or viruses (total 79.0 %), the efficacy of which has not been confirmed through clinical trials. When used in combination, they are often blended for presumed holistic synergistic effects. Of the essential oils recommended, all show some degree of antioxidant activity, 50.0 % demonstrate anti-inflammatory effects and 83.3 % of the essential oils showed antihistaminic activity. Of the essential oils reviewed, 43.8 % are considered non-toxic while the remaining essential oils are considered slightly to moderately toxic (43.7 %) or the toxicity is unknown (12.5 %). Recommendations are made for further research into essential oil combinations.

Severe Lower Extremity Cellulitis Caused by an Unusual Pathogen: Haemophilus Influenzae Type F

We present a case of unusual cellulitis of the lower extremities caused by Haemophilus influenzae (HI). A 64-year-old female with human immunodeficiency virus (HIV) with a suppressed viral load on treatment, presented with severe, very painful cellulitis of her lower extremity. CT scan did not show any gas or collections; however, she was taken to the operating room for concern of necrotizing fasciitis but no evidence of deep tissue involvement was found. Blood culture and wound culture were positive forHI type F (HiF), a newly emergent pathogenic capsulatedHI that has emerged post-HI type B (HiB) vaccination.

Two cases of type-a Haemophilus influenzae meningitis within the same week in the same hospital are phylogenetically unrelated but recently exchanged capsule genes

Haemophilus influenzae causes common and sometimes severe adult and pediatric disease including chronic obstructive respiratory disease, otitis media and infections of the central nervous system. Serotype b strains, with a b-type capsule, have been the historical cause of invasive disease, and the introduction of a serotype b-specific vaccine has led to their decline. However, unencapsulated or non-b-type H. influenzae infections are not prevented by the vaccine and appear to be increasing in frequency. Here we report two pediatric cases of severe central nervous system H. influenzae infection presenting to the same hospital in San Diego, California during the same week in January 2016. Due to good vaccine coverage in this part of the world, H. influenzae cases are normally rare and seeing two cases in the same week was unexpected. We thus suspected a recent transmission chain, and possible local outbreak. To test this hypothesis, we isolated and sequenced whole genomes from each patient and placed them in a phylogenetic tree spanning the known diversity of H. influenzae. Surprisingly, we found that the two isolates (SD2016_1 and SD2016_2) belonged to distantly related lineages, suggesting two independent transmission events and ruling out a local outbreak. Despite being distantly related, the two isolates belong to two different lineages that have exchanged capsule loci in the recent past. Therefore, as in other bacterial pathogens, capsule switching by horizontal gene transfer may be an important evolutionary mechanism of vaccine evasion in H. influenzae.

Molecular epidemiology of invasive Haemophilus influenzae disease in Portugal: an update of the post-vaccine period, 2011-2018

Haemophilus influenzae reference laboratory from Portugal characterized the entire collection of 260 H. influenzae invasive isolates received between 2011 and 2018, with the purpose of updating the last published data (2002-2010). Capsular serotypes and antimicrobial susceptibility patterns were determined. The ftsI gene encoding the transpeptidase domain of PBP3 was sequenced for β-lactamase-negative ampicillin-resistant (BLNAR) isolates. Multilocus sequence typing (MLST) was performed to examine genetic relatedness among isolates. The majority of H. influenzae invasive isolates are nonencapsulated (NTHi-79.2%). Among encapsulated isolates (20.8%), the most characterized serotype was serotype b (13.5%), followed by serotype f (3.1%), serotype a (2.7%), and serotype e (1.5%). In contrast to NTHi that mainly affected the elderly (64.0%; ≥ 65 years old), most encapsulated isolates were characterized in preschool children (55.6%). Comparing the two periods, β-lactamase production increased from 10.4 to 13.5% (p = 0.032) and low-BLNAR (MIC ≥ 1 mg/L) isolates from 7.7 to 10.5% (p = 0.017). NTHi showed high genetic diversity (60.7%), in opposition to encapsulated isolates that were clonal within each serotype. Interestingly, ST103 and ST57 were the predominant STs among NTHi, with ST103 being associated with β-lactamase-producers and ST57 with non-β-lactamase-producers. In Portugal, susceptible and genetically diverse NTHi H. influenzae continues to be responsible for invasive disease, mainly in the elderly. Nevertheless, we are now concerned with Hib circulating in children we believe to have been vaccinated. Our data reiterates the need for continued surveillance, which will be useful in the development of public health prevention strategies.

Complement evasion by the human respiratory tract pathogens Haemophilus influenzae and Moraxella catarrhalis

All infective bacterial species need to conquer the innate immune system in order to colonize and survive in their hosts. The human respiratory pathogens Haemophilus influenzae and Moraxella catarrhalis are no exceptions and have developed sophisticated mechanisms to evade complement-mediated killing. Both bacterial species carry lipooligosaccharides preventing complement attacks and attract and utilize host complement regulators C4b binding protein and factor H to inhibit the classical and alternative pathways of complement activation, respectively. In addition, the regulator of the terminal pathway of complement activation, vitronectin, is hijacked by both bacteria. An array of different outer membrane proteins (OMP) in H. influenzae and M. catarrhalis simultaneously binds complement regulators, but also plasminogen. Several of the bacterial complement-binding proteins are important adhesins and contain highly conserved regions for interactions with the host. Thus, some of the OMP are viable targets for new therapeutics, including vaccines aimed at preventing respiratory tract diseases such as otitis media in children and exacerbations in patients suffering from chronic obstructive pulmonary disease.

Haemophilus parainfluenza bacteremia post-ERCP and cholecystectomy in a pediatric patient: A case report

Haemophilus parainfluenzae is a species that is commonly found in the human respiratory tract. It is an uncommon cause of gastrointestinal infection and bacteremia. Here, we present the case of a 17-year-old boy who developed H. parainfluenzae bacteremia and intraabdominal abscess after endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy followed by elective cholecystectomy within 3 days. The patient was successfully treated with IV ceftriaxone with improvement in symptoms and progressive resolution of his abscess. We report a pediatric case of H. parainfluenzae infection occurring post-ERCP and cholecystectomy, and describe the convergence of two major risk factors for H. parainfluenzae bacteremia in the same pediatric patient.

Clinical Characterization of Invasive Disease Caused by Haemophilus influenzae Serotype b in a High Vaccination Coverage Setting

This national study characterized invasive Haemophilus influenzae serotype b infections. Vaccinated (n = 41) and nonvaccinated (n = 10) cases were similar regarding presentation as meningitis (68.8% vs 90.0%; P = .25), predisposing factors (29.3% vs 20.0%; P = .76), admission to intensive care unit or death (22.0% vs 10.0%; P = 1.00), or sequelae (21.6% vs 10.0%; P = .81). Haemophilus influenzae serotype b occurred in vaccinated, healthy children with comparable disease course.

Haemophilus influenzae Type f Meningitis Complicated by Bilateral Subdural Empyema, Central Venous Thrombosis, and Bilateral Sensorineural Hearing Loss in an Immunocompetent 12-month-old

Haemophilus influenzae is a gram-negative coccobacillus that colonizes the nasopharyngeal surface and upper respiratory tract of healthy individuals and includes six encapsulated serotypes as well as non-encapsulated, non-typeable strains. Since the widespread use of the Haemophilus influenzae type b (Hib) conjugate vaccine implemented in 1990, the majority of invasive illness now seen in the United States is secondary to capsular serotypes other than type b and non-typeable strains with the largest burden of disease affecting the extremes of age-infants and the elderly. We report a case of acute Haemophilus influenzae type f meningitis in a 12-month-old female who was previously healthy and had been fully immunized. She demonstrated clinical improvement on ceftriaxone, but persistent fever and ear-tugging resulted in obtaining an MRI that displayed bilateral subdural empyemas requiring burr-hole craniotomy, central venous thrombosis requiring anticoagulation, and bilateral sensorineural hearing loss requiring cochlear implants. Immunological studies confirmed immunocompetency and appropriate response to her previous Hib vaccination, suggesting a significant impact of bacterial virulence. These complications, with the exception of sensorineural hearing loss, have not been reported in the literature for Haemophilus influenzae type f and should be considered in the care of these patients despite clinical appearance given the severity of complications and potential for acute decompensation. Despite the success of vaccination in reducing invasive disease, cases of H. influenzae meningitis continue to occur via less common encapsulated serotypes with unknown complications, making the management and treatment of these infections more difficult for practitioners.

Disseminated "Haemophilus quentini" infection in a patient with multiple myeloma - a case report and review of the literature

We describe a case report of a 56-year-old male with undiagnosed multiple myeloma who had severe sepsis associated with pneumonia, meningitis, polyarthritis, and osteomyelitis related to invasive "Haemophilus quentini" infection. The genus was misidentified as H. influenzae by the common bacterial identification systems including newly introduced syndromic PCR-based methods. We review the epidemiological, clinical, and laboratory aspects of this rare, cryptic species of Haemophilus.

Capsule Typing of Haemophilus influenzae by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Encapsulated Haemophilus influenzae strains belong to type-specific genetic lineages. Reliable capsule typing requires PCR, but a more efficient method would be useful. We evaluated capsule typing by using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Isolates of all capsule types (a−f and nontypeable; n = 258) and isogenic capsule transformants (types a−d) were investigated. Principal component and biomarker analyses of mass spectra showed clustering, and mass peaks correlated with capsule type-specific genetic lineages. We used 31 selected isolates to construct a capsule typing database. Validation with the remaining isolates (n = 227) showed 100% sensitivity and 92.2% specificity for encapsulated strains (a−f; n = 61). Blinded validation of a supplemented database (n = 50) using clinical isolates (n = 126) showed 100% sensitivity and 100% specificity for encapsulated strains (b, e, and f; n = 28). MALDI-TOF mass spectrometry is an accurate method for capsule typing of H. influenzae.

Bacterial Meningitis Caused by β-lactamase Non-producing Ampicillin-resistant Haemophilus influenzae Type f in an Immunocompetent Woman

We report the case of a 36-year-old previously healthy woman who presented with fever and headache. Blood and cerebrospinal cultures and a bacterial analysis revealed the presence of β-lactamase non-producing ampicillin-resistant Haemophilus influenzae type f (Hif) with sequence type 124. Accordingly, the patient was diagnosed with bacterial meningitis with bacteremia caused by Hif. She had normal humoral immunity, and antibiotic therapy rapidly improved her condition. Our case indicates that serotype replacement can occur in Japan and suggests that a certain sequence type causes invasive Haemophilus influenzae disease, regardless of host immunity.

Intensive Patient Treatment

Intensive care units (ICUs) are treating hospital’s poorest patients that need medical assistance during the most extreme period of their life. Intensive patients are treated with extensive invasive procedures, which may cause a risk of hospital infections in 10–30% of the cases. More than half of these infections can be prevented. The patients are often admitted directly from outside the hospital or from abroad with trauma after accidents, serious heart and lung conditions, sepsis and other life-threatening diseases. Infection or carrier state of microbes is often unknown on arrival and poses a risk of transmission to other patients, personnel and the environment. Patients that are transferred between different healthcare levels and institutions with unknown infection may be a particular risk for other patients. In spite of the serious state of the patients, many ICUs have few resources and are overcrowded and understaffed, with a lack of competent personnel. ICU should have a large enough area and be designed, furnished and staffed for a good, safe and effective infection control. The following chapter is focused on practical measures to reduce the incidence of infections among ICU patients.

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.

The return of Pfeiffer's bacillus: Rising incidence of ampicillin resistance in Haemophilus influenzae

Haemophilus influenzae, originally named Pfeiffer's bacillus after its discoverer Richard Pfeiffer in 1892, was a major risk for global health at the beginning of the 20th century, causing childhood pneumonia and invasive disease as well as otitis media and other upper respiratory tract infections. The implementation of the Hib vaccine, targeting the major capsule type of H. influenzae, almost eradicated the disease in countries that adapted the vaccination scheme. However, a rising number of infections are caused by non-typeable H. influenzae (NTHi), which has no capsule and against which the vaccine therefore provides no protection, as well as other serotypes equally not recognised by the vaccine. The first line of treatment is ampicillin, but there is a steady rise in ampicillin resistance. This is both through acquired as well as intrinsic mechanisms, and is cause for serious concern and the need for more surveillance. There are also increasing reports of new modifications of the intrinsic ampicillin-resistance mechanism leading to resistance against cephalosporins and carbapenems, the last line of well-tolerated drugs, and ampicillin-resistant H. influenzae was included in the recently released priority list of antibiotic-resistant bacteria by the WHO. This review provides an overview of ampicillin resistance prevalence and mechanisms in the context of our current knowledge about population dynamics of H. influenzae.

The Pulmonary Extracellular Matrix Is a Bactericidal Barrier Against Haemophilus influenzae in Chronic Obstructive Pulmonary Disease (COPD): Implications for an in vivo Innate Host Defense Function of Collagen VI

Non-typeable Haemophilus influenzae (NTHi) is a Gram-negative human commensal commonly residing in the nasopharynx of preschool children. It occasionally causes upper respiratory tract infection such as acute otitis media, but can also spread to the lower respiratory tract causing bronchitis and pneumonia. There is increasing recognition that NTHi has an important role in chronic lower respiratory tract inflammation, particularly in persistent infection in patients suffering from chronic obstructive pulmonary disease (COPD). Here, we set out to assess the innate protective effects of collagen VI, a ubiquitous extracellular matrix component, against NTHi infection in vivo. In vitro, collagen VI rapidly kills bacteria through pore formation and membrane rupture, followed by exudation of intracellular content. This effect is mediated by specific binding of the von Willebrand A (VWA) domains of collagen VI to the NTHi surface adhesins protein E (PE) and Haemophilus autotransporter protein (Hap). Similar observations were made in vivo specimens from murine airways and COPD patient biopsies. NTHi bacteria adhered to collagen fibrils in the airway mucosa and were rapidly killed by membrane destabilization. The significance in host-pathogen interplay of one of these molecules, PE, was highlighted by the observation that it confers partial protection from bacterial killing. Bacteria lacking PE were more prone to antimicrobial activity than NTHi expressing PE. Altogether the data shed new light on the carefully orchestrated molecular events of the host-pathogen interplay in COPD and emphasize the importance of the extracellular matrix as a novel branch of innate host defense.

Epidemiological analysis and rapid detection by one-step multiplex PCR assay of Haemophilus influenzae in children with respiratory tract infections in Zhejiang Province, China

Background

Haemophilus influenzae (H. influenzae) is one of the most important pathogenic bacteria causing respiratory tract infection diseases in children. There are two main types of H. influenzae, encapsulated H. influenzae and nontypeable H. influenzae (NTHi). Serotype b of H. influenzae (Hib) used to be the main epidemic type of H. influenzae, causing the invasive infection. However, the epidemiology of invasive H. influenzae disease has changed substantially, and most invasive diseases are now caused by NTHi and other serotypes of H. influenzae. The aim of this study was to determine the main epidemic strains of H. influenzae in Zhejiang Province in China, and establish a one-step multiplex PCR assay to distinguish H. influenzae from other bacteria associated with respiratory tract infections, and distinguish encapsulated H. influenzae from NTHi.

Method

In this study, bacterial culture and serum agglutination testing were used to determine the most prevalent serotype of H. influenzae, and the results have served as a gold standard for clinical diagnosis. We also designed a one-step multiplex PCR assay using several kinds of standard strains of respiratory tract infection bacteria, to examine the stability, specificity, and detection limit of the PCR assays. We then used 1514 nasopharyngeal secretion (NPS) samples collected from children with respiratory tract infections to verify the specificity and sensitivity of the PCR assay.

Results

The bacterial culture and serum agglutination test results showed that the positive rates of H. influenzae and encapsulated H. influenzae were 18.49 and 1.18%, respectively. The PCR results showed that the detection limit of the multiplex PCR assay was 1.89 × 10³ copies /μL, the ompP6 positive rate was 19.35%, and the bexA positive rate was 1.32%. The sensitivity and specificity of the multiplex PCR were 100 and 99.86%, respectively.

Conclusions

According to our study, the most prevalent H. influenzae subtype in Zhejiang Province was NTHi, account for 93.57%; the one-step multiplex PCR assay we established can be used as the differential detection of clinical H. influenzae strains, replacing routine bacterial culture and serum agglutination testing.

Nontypable Haemophilus influenzae Septicemia and Urinary Tract Infection Associated with Renal Stone Disease

Introduction:

Haemophilus influenzae commonly causes upper respiratory tract infections and has only rarely been reported etiology of urinary tract infections. Since the introduction of the Haemophilus influenzae b (Hib) vaccine, non-typable haemophilus species now cause the majority of invasive disease in Europe.

Case Report:

We report a case of an adult man with non-typable Haemophilus influenzae septicemia, urinary tract infection and bilateral renal stone disease. The patient presented with right sided flank pain and a CT scan showed bilateral renal stones and a right sided ureteral stone causing obstruction.

Results and Discussion:

Haemophilus influenzae was identified in blood and urine and despite a tendency of increasing antibiotic resistance among Haemophilus influenzae, our strain was susceptible to all antibiotics tested. Treatment consisted of 3 days of intravenous cefuroxime, insertion of a right sided JJ ureteric stent and 5 days of peroral ciprofloxacin after discharge. Physicians and microbiologists should be aware of Haemophilus influenzae as a possible urinary tract pathogen, especially when urinary tract abnormalities are present, and take the risk of antibiotic resistance into consideration at initial treatment.

Benzylpenicillin versus wide-spectrum beta-lactam antibiotics as empirical treatment of Haemophilus influenzae-associated lower respiratory tract infections in adults; a retrospective propensity score-matched study

There is consensus that definitive therapy for infections with H. influenzae should include antimicrobial agents with clinical breakpoints against the bacterium. In Scandinavia, benzylpenicillin is the recommended empirical treatment for community-acquired pneumonia (CAP) except in very severe cases. However, the effect of benzylpenicillin on H. influenzae infections has been debated. The aim of this study was to compare the outcomes of patients given benzylpenicillin with patients given wide-spectrum beta-lactams (WSBL) as empirical treatment of lower respiratory tract H. influenzae infections requiring hospital care. We identified 481 adults hospitalized with lower respiratory tract infection by H. influenzae, bacteremic and non-bacteremic. Overall, 30-day mortality was 9% (42/481). Thirty-day mortality, 30-day readmission rates, and early clinical response rates were compared in patients receiving benzylpenicillin (n = 199) and a WSBL (n = 213) as empirical monotherapy. After adjusting for potential confounders, empirical benzylpenicillin treatment was not associated with higher 30-day mortality neither in a multivariate logistic regression (aOR 2.03 for WSBL compared to benzylpenicillin, 95% CI 0.91–4.50, p = 0.082), nor in a propensity score-matched analysis (aOR 2.14, 95% CI 0.93–4.92, p = 0.075). Readmission rates did not significantly differ between the study groups, but early clinical response rates were significantly higher in the WSBL group (aOR 2.28, 95% CI 1.21–4.31, p = 0.011), albeit still high in both groups (84 vs 81%). In conclusion, despite early clinical response rates being slightly lower for benzylpenicillin compared to WSBL, we found no support for increased mortality or readmission rates in patients empirically treated with benzylpenicillin for lower respiratory tract infections by H. influenzae.

Fulminant Haemophilus Influenzae Type a Infection in a 4-year-old with Previously Undiagnosed Asplenic Heterotaxy

The post Hib-vaccine era has resulted in increased cases of invasive, non-Hib, Haemophilus influenzae infections. One of the encapsulated species, type a, displays the most similarity in virulence to type b. Our patient, a fully vaccinated 4-year-old female, with newly diagnosed asplenia in the setting of heterotaxy, had a prolonged hospital course with disseminated Haemophilus influenzae type a infection.

Epidemiology of Invasive Haemophilus influenzae Disease, Europe, 2007-2014

We describe the epidemiology of invasive Haemophilus influenzae disease during 2007-2014 in 12 European countries and assess overall H. influenzae disease trends by serotype and patient age. Mean annual notification rate was 0.6 cases/100,000 population, with an increasing annual trend of 3.3% (95% CI 2.3% to 4.3%). The notification rate was highest for patients <1 month of age (23.4 cases/100,000 population). Nontypeable H. influenzae (NTHi) caused 78% of all cases and showed increasing trends among persons <1 month and >20 years of age. Serotype f cases showed an increasing trend among persons >60 years of age. Serotype b cases showed decreasing trends among persons 1-5 months, 1-4 years, and >40 years of age. Sustained success of routine H. influenzae serotype b vaccination is evident. Surveillance systems must adopt a broad focus for invasive H. influenzae disease. Increasing reports of NTHi, particularly among neonates, highlight the potential benefit of a vaccine against NTHi.

Paediatric invasive Haemophilus influenzae in Queensland, Australia, 2002-2011: Young Indigenous children remain at highest risk

AIM

Haemophilus influenzae continues to cause invasive disease in children despite widespread Hib immunisation. The significance of non-B serotypes continues to be investigated, with evidence of increased invasive non-typeable H. influenzae (NTHi) world-wide. The aim of this study was to examine the current epidemiological and clinical features of invasive H. influenzae disease in children in Queensland, Australia.

METHODS

A retrospective review was performed of all cases of invasive H. influenzae disease in children <18 years of age in Queensland between January 2002 and December 2011. Cases were identified from pathology records and data requested from treating hospitals.

RESULTS

Laboratory data were obtained for 144 cases and clinical/demographic data for 123 cases. The majority (72%) of cases were children <5 years of age. Annual incidence rate for all children <5 years was 7.4/100 000, and for Aboriginal and Torres Strait Islander children <5 years was 10.2/100 000. Serotype was reported for 132 isolates, 69 NTHi and 63 encapsulated strains. The most common clinical diagnoses were pneumonia, meningitis and bacteraemia without clinical focus. Of the patients, 5 patients died, and 12 had significant morbidity at hospital discharge.

CONCLUSIONS

While rates of invasive H. influenzae disease have decreased dramatically following the introduction of Hib vaccination, H. influenzae remains a cause of significant morbidity and mortality, and Aboriginal and Torres Strait Islander children remain particularly vulnerable.

The DNABII family of proteins is comprised of the only nucleoid associated proteins required for nontypeable Haemophilus influenzae biofilm structure

Biofilms play a central role in the pathobiology of otitis media (OM), bronchitis, sinusitis, conjunctivitis, and pneumonia caused by nontypeable Haemophilus influenzae (NTHI). Our previous studies show that extracellular DNA (eDNA) and DNABII proteins are essential components of biofilms formed by NTHI. The DNABII protein family includes integration host factor (IHF) and the histone‐like protein HU and plays a central role in NTHI biofilm structural integrity. We demonstrated that immunological targeting of these proteins during NTHI‐induced experimental OM in a chinchilla model caused rapid clearance of biofilms from the middle ear. Given the essential role of DNABII proteins in maintaining the structure of an NTHI biofilm, we investigated whether any of the other nucleoid associated proteins (NAPs) expressed by NTHI might play a similar role, thereby serving as additional target(s) for intervention. We demonstrated that although several NAPs including H‐NS, CbpA, HfQ and Dps are present within the biofilm extracellular matrix, only the DNABII family of proteins is critical for the structural integrity of the biofilms formed by NTHI. We have also demonstrated that IHF and HU are located at distinct regions within the extracellular matrix of NTHI biofilms formed in vitro, indicative of independent functions of these two proteins.

Molecular Serotype-Specific Identification of Non-type b Haemophilus influenzae by Loop-Mediated Isothermal Amplification

Over the past four decades, the incidence of meningitis caused by Haemophilus influenzae in children has decreased due to widespread vaccination against H. influenzae type b (Hib). The incidence of invasive diseases due to H. influenzae types not included in the vaccines, however, has increased. At present, there are a limited number of diagnostics available to detect non-type b H. influenzae. To address this issue, we developed a rapid, simple, and cost-effective method for detecting serotypes of H. influenzae. We designed LAMP primer sets based on published sequences for H. influenzae capsular types a, c, d, e, and f. The assay was evaluated to determine test reactivity, specificity, and sensitivity. To support its use in patients with suspected meningitis, we evaluated the detection limit of the non-Hib serotype specific LAMP assay using bacterial genomic DNA-spiked cerebrospinal fluid (CSF) specimens. The reactivity and specificity of the LAMP assays were confirmed using six serotypes and non-typeable H. influenzae strains, plus eight strains of other Haemophilus species and non-Haemophilus genera. The detection limits of the LAMP assay for capsular types a, c, d, e, and f were 10², 10², 10², 10³, and 10 copies per reaction, while those of the PCR assay were 10⁴, 10⁴, 10³, 10³, and 10⁴ genome copies per reaction, respectively. Using DNA-spiked CSF specimens, the detection limit of the LAMP assay was equivalent to that using purified DNA as the template. However, the detection limit of the PCR was reduced from 10³ to 10⁴ genome copies per reaction for serotype d and from 10³ to 10⁵ genome copies per reaction for serotype e. To the best of our knowledge, this is the first report of a serotype-specific identification assay for H. influenzae using the LAMP method. Our results suggest the potential of LAMP methods for patients with suspected meningitis in resource-limited laboratories or public health surveillance systems.

Conservation and Recombination in the Genome Sequence of Haemophilus influenzae Type f WAPHL1

We report here the second draft genome sequence of a bloodstream isolate of Haemophilus influenzae serotype f. Three discrete 3.1- to 7.8-kb sites contained 80% of the variability in the genome, consistent with recombination in known virulence factors.

Non-Type b Haemophilus influenzae Invasive Infections in North Dakota and South Dakota, 2013-2015

Reports of children with non-type b Haemophilus influenzae infection in the United States in recent years have been limited. Here, we report the spectrum and severity of disease associated with invasive non-type b H influenzae infection in 17 patients at 2 tertiary-care children's hospitals over a 2-year period. Meningitis was the most common diagnosis. The majority of the patients had neurologic sequelae, and 1 patient died. The high proportions of hospitalization, intensive care utilization, and neurologic complications reveal that non-type b H influenzae infection was associated with significant morbidity in this pediatric population.