Epidemiology of Haemophilus influenzae bacteremia: a multi-national population-based assessment

Comparing the Microbiome of the Adenoids in Children with Secretory Otitis Media and Children without Middle Ear Effusion

BACKGROUND

The adenoids, primary sites of microbial colonization in the upper airways, can influence the development of various conditions, including otitis media with effusion (OME). Alterations in the adenoid microbiota have been implicated in the pathogenesis of such conditions.

AIM

This study aims to utilize 16S rRNA genetic sequencing to identify and compare the bacterial communities on the adenoid surfaces of children with OME and children with healthy middle ears. Additionally, we seek to assess the differences in bacterial diversity between these two groups.

MATERIALS AND METHODS

We collected adenoid surface swabs from forty children, divided into two groups: twenty samples from children with healthy middle ears and twenty samples from children with OME. The V3-V4 hypervariable region of the bacterial 16S rRNA gene was amplified and sequenced using the Illumina MiSeq platform. Alpha and beta diversity indices were calculated, and statistical analyses were performed to identify significant differences in bacterial composition.

RESULTS

Alpha diversity analysis, using Pielou's index, revealed significantly greater evenness in the bacterial communities on the adenoid surfaces of the healthy ear group compared with the OME group. Beta diversity analysis indicated greater variability in the microbial composition of the OME group. The most common bacterial genera in both groups were Haemophilus, Fusobacterium, Streptococcus, Moraxella, and Peptostreptococcus. The healthy ear group was primarily dominated by Haemophilus and Streptococcus, whereas the OME group showed higher abundance of Fusobacterium and Peptostreptococcus. Additionally, the OME group exhibited statistically significant higher levels of Alloprevotella, Peptostreptococcus, Porphyromonas, Johnsonella, Parvimonas, and Bordetella compared with the healthy ear group.

CONCLUSION

Our study identified significant differences in the bacterial composition and diversity on the adenoid surfaces of children with healthy middle ears and those with OME. The OME group exhibited greater microbial variability and higher abundances of specific bacterial genera. These findings suggest that the adenoid surface microbiota may play a role in the pathogenesis of OME. Further research with larger sample sizes and control groups is needed to validate these results and explore potential clinical applications.

Bacitracin agar vs. oleandomycin disk supplemented chocolate agar for the recovery of Haemophilus influenzae in diagnostic samples: A prospective comparison

Haemophilus influenzae is an important pathogen able to cause various forms of respiratory and invasive disease. To provide high sensitivity for detection, culture media must inhibit growth of residential flora from the respiratory tract. This study aimed to identify and compare the diagnostic and economic advantages of using bacitracin containing selective agar (SEL) or oleandomycin disk supplemented chocolate agar (CHOC). Growth and semi-quantitative abundance of H. influenzae and growth suppression of residential flora was prospectively assessed in a 28-week period. H. influenzae was identified in 164 (5 %) of all included samples: CHOC and SEL, CHOC only, and SEL only were positive in 95, 24, and 45 cases. Diagnostic superiority of SEL was primarily attributable to the results of throat swabs. However, on average, € 200 had to be spent for the detection of each additional isolate that was recovered only because of additional incubation on SEL.

National Danish surveillance of invasive clinical Haemophilus influenzae isolates and their resistance profile

INTRODUCTION

This study aimed to investigate the epidemiology, serotype distribution, phenotypical antibiogram, and molecular resistance gene characteristics of invasive Haemophilus influenzae infections in Denmark from 2014 to 2022. Additionally, the potential impact of outdoor temperature and COVID-19 restrictions on the epidemiology of H. influenzae was assessed.

MATERIALS AND METHODS

Invasive H. influenzae isolates were received from patients with positive culture results from cerebrospinal fluid, blood, or other sterile sites. Sample data were obtained from the Danish laboratory surveillance system/MiBa database, and whole-genome sequencing (WGS) was performed on the isolates. The incidence rates and distribution of H. influenzae cases were analyzed, and antibiotic susceptibility were assessed.

RESULTS

A total of 1,007 invasive H. influenzae cases were identified, with serotyping conducted for 752 (74.7%) isolates. The median incidence per year of H. influenzae was 2.0 cases per 100,000, with the highest incidence in 2014 and the lowest in 2020. The majority of H. influenzae isolates were non-typeable H. influenzae (NTHi), while the most prominent serotypes were serotype f followed by serotype b. Bacteremia cases accounted for the majority (88.6%) of occurrences, although meningitis cases showed an increasing trend during the time period. The age group 85+ exhibited the highest incidence. The implementation of COVID-19 preventive interventions in 2020 resulted in a significant reduction in H. influenzae incidence, which returned to pre-COVID levels in 2021. A negative correlation was observed between monthly H. influenzae cases and outdoor temperature. An overall level of genetic beta-lactamase resistance of 26.3% was observed divided into 10.6% beta-lactamase-positive ampicillin-resistant (gBLPAR), 13.6% beta-lactamase-negative ampicillin-resistant (gBLNAR) and 2.1% beta-lactamase-positive amoxicillin clavulanate-resistant (gBLPACR). Other non-beta-lactam resistance traits were detected in 7.6% of isolates (primarily aminoglycoside-modifying enzymes).

CONCLUSION

The overall incidence of H. influenzae in Denmark returned to stable levels after the COVID-19 epidemic, with NTHi strains dominating. The COVID-19 preventive interventions led to a major reduction in incidence. A significant negative correlation between the incidence of H. influenzae and temperature was observed. The study revealed an overall genetic beta-lactam resistance rate of 26.3%, and the concordance between genotypic and phenotypic beta-lactam resistance was high (98.2%).

Non-typeable Haemophilus influenzae airways infection: the next treatable trait in asthma?

Asthma is a complex, heterogeneous condition that affects over 350 million people globally. It is characterised by bronchial hyperreactivity and airways inflammation. A subset display marked airway neutrophilia, associated with worse lung function, higher morbidity and poor response to treatment. In these individuals, recent metagenomic studies have identified persistent bacterial infection, particularly with non-encapsulated strains of the Gram-negative bacterium Haemophilus influenzae. Here we review knowledge of non-typeable H. influenzae (NTHi) in the microbiology of asthma, the immune consequences of mucosal NTHi infection, various immune evasion mechanisms, and the clinical implications of NTHi infection for phenotyping and targeted therapies in neutrophilic asthma. Airway neutrophilia is associated with production of neutrophil chemokines and proinflammatory cytokines in the airways, including interleukin (IL)-1β, IL-6, IL-8, IL-12, IL-17A and tumour necrosis factor. NTHi adheres to and invades the lower respiratory tract epithelium, inducing the NLR family pyrin domain containing 3 (NLRP3) and absent in melanoma 2 (AIM2) inflammasomes. NTHi reduces expression of tight-junction proteins, impairing epithelial integrity, and can persist intracellularly. NTHi interacts with rhinoviruses synergistically via upregulation of intracellular cell adhesion molecule 1 and promotion of a neutrophilic environment, to which NTHi is adapted. We highlight the clinical relevance of this emerging pathogen and its relevance for the efficacy of long-term macrolide therapy in airways diseases, we identify important unanswered questions and we propose future directions for research.

A Report of Haemophilus influenzae Bacteremia With Acute Pelvic Inflammatory Disease

Sexually-transmitted organisms that frequently originate from the flora of the lower genital tract are often implicated in pelvic inflammatory disease (PID). Haemophilus influenzae, a pathogen found primarily in the upper respiratory tract, has been rarely associated with PID. Here we report a case of a young woman with PID whose blood cultures grew H. influenzae biotype II, a reminder that the endometrium can be the source of systemic H. influenzae infection when no typical primary focus is found.

Clinical and microbiological characteristics of adult invasive Haemophilus influenzae infections: results of a 14-year single-center experience from Hungary

To describe the characteristics of adult invasive H. influenzae disease, 34 patients diagnosed at a single tertiary center between 2004 and 2017 were analyzed in a retrospective case series study. The annual estimated incidence was 0.1 cases/100.000 inhabitants. Dominant source of infection was pneumonia accompanied by sepsis (62%) and caused by nontypeable strains (74%) with low ampicillin resistance (14%). Survival (94%) and complication rates were high (35%). Main empirical treatments were ceftriaxone or levofloxacine.

The challenges of treating tracheobronchitis in a laryngectomee due to nontypeable Haemophilus influenzae: a case report

Background

Laryngectomees run the risk of developing severe respiratory tract infections especially during the winter and when they do not wear a stoma cover. A case of severe tracheobronchitis in a laryngectomee is presented that illustrates the risks and difficulties encountered in managing this infection in a neck breather.

Case presentation

A 76-year-old Caucasian man, a laryngectomee, presented with bacterial tracheobronchitis and conjunctivitis due to beta-lactamase-producing nontypeable Haemophilus influenzae. He was febrile (38.9 °C; 102.0 F), and had repeated episodes of hypertension. He was treated with levofloxacin 500 mg/day, ciprofloxacin eye drops, acetaminophen, and guaifenesin. Humidification of his trachea and the airway was sustained by insertions of saline into the stoma as well as breathing humidified air. The main challenge was to maintain the patency of his airway as the mucus was very dry and viscous and tended to stick to the walls of his trachea and the stoma. His condition improved within 7 days and he had a complete recovery.

Conclusions

Maintaining the patency of the airway in laryngectomees who suffer from lower respiratory tract infection is of utmost importance as the mucus can be very dry and viscous and can stick to the walls of the trachea and the stoma.

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.

Rationale and methods of a randomized controlled trial of immunogenicity, safety and impact on carriage of pneumococcal conjugate and polysaccharide vaccines in infants in Papua New Guinea

BACKGROUND

Children in third-world settings including Papua New Guinea (PNG) experience early onset of carriage with a broad range of pneumococcal serotypes, resulting in a high incidence of severe pneumococcal disease and deaths in the first 2 years of life. Vaccination trials in high endemicity settings are needed to provide evidence and guidance on optimal strategies to protect children in these settings against pneumococcal infections.

METHODS

This report describes the rationale, objectives, methods, study population, follow-up and specimen collection for a vaccination trial conducted in an endemic and logistically challenging setting in PNG. The trial aimed to determine whether currently available pneumococcal conjugate vaccines (PCV) are suitable for use under PNG's accelerated immunization schedule, and that a schedule including pneumococcal polysaccharide vaccine (PPV) in later infancy is safe and immunogenic in this high-risk population.

RESULTS

This open randomized-controlled trial was conducted between November 2011 and March 2016, enrolling 262 children aged 1 month between November 2011 and April 2014. The participants were randomly allocated (1:1) to receive 10-valent PCV (10vPCV) or 13-valent PCV (13vPCV) in a 1-2-3-month schedule, with further randomization to receive PPV or no PPV at age 9 months, followed by a 1/5th PPV challenge at age 23 months. A total of 1229 blood samples were collected to measure humoral and cellular immune responses and 1238 nasopharyngeal swabs to assess upper respiratory tract colonization and carriage load. Serious adverse events were monitored throughout the study. Of the 262 children enrolled, 87% received 3 doses of PCV, 79% were randomized to receive PPV or no PPV at age 9 months, and 67% completed the study at 24 months of age with appropriate immunization and challenge.

CONCLUSION

Laboratory testing of the many samples collected during this trial will determine the impact of the different vaccine schedules and formulations on nasopharyngeal carriage, antibody production and function, and immune memory. The final data will inform policy on pneumococcal vaccine schedules in countries with children at high risk of pneumococcal disease by providing direct comparison of an accelerated schedule of 10vPCV and 13vPCV and the potential advantages of PPV following PCV immunization.

TRIAL REGISTRATION

ClinicalTrials.gov CTN NCT01619462, retrospectively registered on May 28, 2012.

Fetal Tissues Tested for Microbial Sterility by Culture- and PCR-Based Methods Can be Safely Used in Clinics

Cell preparations to be used in clinical practice must be free of infectious agents. Safety concerns are especially elevated upon the use of human fetal tissues, which are otherwise highly advantageous in cell therapy. We demonstrate that treating fetal samples with antibiotic, extensive washing, and homogenization prior to cryoconservation efficiently removes microbes in general. Screening a large collection by an automatic culture system showed that 89.2% fetal tissue samples were sterile, while contamination was detected in 10.8% samples. Liver and chorion were contaminated more than the brain, kidney, lung, and soft tissues. Broad-range PCR from the bacterial 16s rRNA gene was adopted as a confirmatory assay; however, the concordance between the culture-based and PCR assays was weak. Taxonomic identification was done for contaminated samples by bacteriological methods and sequencing 16s rRNA PCR products. The two approaches revealed different spectra of taxonomic groups sharing only Lactobacillus, the most frequently found genus. In addition, other representatives of vaginal microbiota were detected by culture-based identification, while PCR product sequencing has also revealed a subset of nosocomial microorganisms. Importantly, species known to cause sepsis were identified by both techniques, arguing for their indispensability and mutual complementarity. We suggest that most contaminations are taken up during collection of fetal material rather than originating from an in utero infection. In conclusion, a rigorous microbiological control by culture and PCR is a prerequisite for safe clinical use of fetal tissue suspensions.

Evaluation of urine pneumococcal antigen test performance among adults in Western Kenya

When used in an area of rural western Kenya, the BinaxNOW® urine antigen test had a sensitivity of 67% (95% Confidence Interval [CI]: 43-85%) among 21 adults ≥15 years old with acute respiratory illnesses and pneumococcal bacteremia and a specificity of 98% (95% CI: 96-99%) among 660 adults ≥15 years old without fever or cough. The specificity of the test was not significantly affected by pneumococcal colonization, regardless of patients' HIV status, age, or sex. Use of the pneumococcal urine antigen test in clinical assessments of adults in Africa with acute respiratory illness is a viable option regardless of whether a patient is colonized by pneumococci, even among HIV-infected adults, although the moderate sensitivity of the urine antigen test indicates that the test is probably best used clinically as part of a panel with other tests that can detect pneumococci.

Haemophilus haemolyticus Interaction with Host Cells Is Different to Nontypeable Haemophilus influenzae and Prevents NTHi Association with Epithelial Cells

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen that resides in the upper respiratory tract and contributes to a significant burden of respiratory related diseases in children and adults. Haemophilus haemolyticus is a respiratory tract commensal that can be misidentified as NTHi due to high levels of genetic relatedness. There are reports of invasive disease from H. haemolyticus, which further blurs the species boundary with NTHi. To investigate differences in pathogenicity between these species, we optimized an in vitro epithelial cell model to compare the interaction of 10 H. haemolyticus strains with 4 NTHi and 4 H. influenzae-like haemophili. There was inter- and intra-species variability but overall, H. haemolyticus had reduced capacity to attach to and invade nasopharyngeal and bronchoalveolar epithelial cell lines (D562 and A549) within 3 h when compared with NTHi. H. haemolyticus was cytotoxic to both cell lines at 24 h, whereas NTHi was not. Nasopharyngeal epithelium challenged with some H. haemolyticus strains released high levels of inflammatory mediators IL-6 and IL-8, whereas NTHi did not elicit an inflammatory response despite higher levels of cell association and invasion. Furthermore, peripheral blood mononuclear cells stimulated with H. haemolyticus or NTHi released similar and high levels of IL-6, IL-8, IL-10, IL-1β, and TNFα when compared with unstimulated cells but only NTHi elicited an IFNγ response. Due to the relatedness of H. haemolyticus and NTHi, we hypothesized that H. haemolyticus may compete with NTHi for colonization of the respiratory tract. We observed that in vitro pre-treatment of epithelial cells with H. haemolyticus significantly reduced NTHi attachment, suggesting interference or competition between the two species is possible and warrants further investigation. In conclusion, H. haemolyticus interacts differently with host cells compared to NTHi, with different immunostimulatory and cytotoxic properties. This study provides an in vitro model for further investigation into the pathogenesis of Haemophilus species and the foundation for exploring whether H. haemolyticus can be used to prevent NTHi disease.

Population-based epidemiology and microbiology of community-onset bloodstream infections

Bloodstream infection (BSI) is a major cause of infectious disease morbidity and mortality worldwide. While a positive blood culture is mandatory for establishment of the presence of a BSI, there are a number of determinants that must be considered for establishment of this entity. Community-onset BSIs are those that occur in outpatients or are first identified <48 h after admission to hospital, and they may be subclassified further as health care associated, when they occur in patients with significant prior health care exposure, or community associated, in other cases. The most common causes of community-onset BSI include Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae. Antimicrobial-resistant organisms, including methicillin-resistant Staphylococcus aureus and extended-spectrum β-lactamase/metallo-β-lactamase/carbapenemase-producing Enterobacteriaceae, have emerged as important etiologies of community-onset BSI.

Nasopharyngeal and Adenoid Colonization by Haemophilus influenzae and Haemophilus parainfluenzae in Children Undergoing Adenoidectomy and the Ability of Bacterial Isolates to Biofilm Production

Haemophili are pathogenic or opportunistic bacteria often colonizing the upper respiratory tract mucosa. The prevalence of Haemophilus influenzae (with serotypes distribution), and H. parainfluenzae in the nasopharynx and/or the adenoid core in children with recurrent pharyngotonsillitis undergoing adenoidectomy was assessed. Haemophili isolates were investigated for their ability to biofilm production.Nasopharyngeal swabs and the adenoid core were collected from 164 children who underwent adenoidectomy (2-5 years old). Bacteria were identified by the standard methods. Serotyping of H. influenzae was performed using polyclonal and monoclonal antisera. Biofilm formation was detected spectrophotometrically using 96-well microplates and 0.1% crystal violet.Ninety seven percent (159/164) children who underwent adenoidectomy were colonized by Haemophilus spp. The adenoid core was colonized in 99.4% (158/159) children, whereas the nasopharynx in 47.2% (75/159) children (P < 0.0001). In 32% (51/159) children only encapsulated (typeable) isolates of H. influenzae were identified, in 22.6% (36/159) children only (nonencapsulated) H. influenzae NTHi (nonencapsulated) isolates were present, whereas 7.5% (12/159) children were colonized by both types. 14.5% (23/159) children were colonized by untypeable (rough) H. influenzae. In 22% (35/159) children H. influenzae serotype d was isolated. Totally, 192 isolates of H. influenzae, 96 isolates of H. parainfluenzae and 14 isolates of other Haemophilus spp. were selected. In 20.1% (32/159) children 2 or 3 phenotypically different isolates of the same species (H. influenzae or H. parainfluenzae) or serotypes (H. influenzae) were identified in 1 child. 67.2% (129/192) isolates of H. influenzae, 56.3% (54/96) isolates of H. parainfluenzae and 85.7% (12/14) isolates of other Haemophilus spp. were positive for biofilm production. Statistically significant differences (P = 0.0029) among H. parainfluenzae biofilm producers and nonproducers in the adenoid core and the nasopharynx were detected.H. influenzae and H. parainfluenzae carriage rate was comparatively higher in the adenoid core than that in the nasopharynx in children undergoing adenoidectomy, suggesting that their involvement in chronic adenoiditis. The growth in the biofilm seems to be an important feature of haemophili colonizing the upper respiratory tract responsible for their persistence.

Clinical and molecular epidemiology of haemophilus influenzae causing invasive disease in adult patients

Objectives

The epidemiology of invasive Haemophilus influenzae (Hi) has changed since the introduction of the Hi type b (Hib) vaccine. The aim of this study was to analyze the clinical and molecular epidemiology of Hi invasive disease in adults.

Methods

Clinical data of the 82 patients with Hi invasive infections were analyzed. Antimicrobial susceptibility, serotyping, and genotyping were studied (2008–2013).

Results

Men accounted for 63.4% of patients (whose mean age was 64.3 years). The most frequent comorbidities were immunosuppressive therapy (34.1%), malignancy (31.7%), diabetes, and COPD (both 22%). The 30-day mortality rate was 20.7%. The majority of the strains (84.3%) were nontypeable (NTHi) and serotype f was the most prevalent serotype in the capsulated strains. The highest antimicrobial resistance was for cotrimoxazole (27.1%) and ampicillin (14.3%). Twenty-three isolates (32.9%) had amino acid changes in the PBP3 involved in resistance. Capsulated strains were clonal and belonged to clonal complexes 6 (serotype b), 124 (serotype f), and 18 (serotype e), whereas NTHi were genetically diverse.

Conclusions

Invasive Hi disease occurred mainly in elderly and those with underlying conditions, and it was associated with a high mortality rate. NTHi were the most common cause of invasive disease and showed high genetic diversity.

Pediatric invasive Haemophilus influenzae infections in Israel in the era of Haemophilus influenzae type b vaccine: a nationwide prospective study

BACKGROUND

The conjugated Haemophilus influenzae (Hi) type b vaccine caused a marked decrease in invasive Hi disease rates. Nonencapsulated Hi infection now constitutes most invasive Hi morbidity and mortality. This study examines invasive Hi infection incidence in Israel in the postvaccine era years, 2003-2012, and characterizes the epidemiology, clinical diagnosis and case fatality rates of invasive Hi disease in children <15 years of age.

METHODS

An ongoing, nationwide prospective surveillance program for invasive Hi infections in Israel. Epidemiologic and clinical data were collected. Diagnoses were classified as meningitis, pneumonia, bacteremia/sepsis and other clinical foci.

RESULTS

Overall, 389 cases of invasive Hi infections were identified; 242 (62%) nontypable Hi (NTHi), 103 (26%) Hi type b (Hib) and 41 (11%) encapsulated non-b Hi (enbHi). Children <1 year of age accounted for 51% of the overall disease. Invasive Hi disease incidence in children <15 years of age was stable with a mean annual incidence (per 100,000) of 2.0 ± 0.4. The highest incidence of invasive Hi infections was among infants <1 year with rates of 6.2, 4.9, 1.6 and 12.7 for NTHi, Hib, enbHi and total Hi, respectively. The clinical diagnoses of NTHi and enbHi were similar, but differed from Hib with the former presenting mostly as isolated sepsis/bacteremia and the latter primarily as meningitis. Among children with invasive Hib infection, 40% were classified as vaccine failure.

CONCLUSIONS

In the post-Hib vaccination era, invasive Hi morbidity and mortality are largely attributed to NTHi sepsis. Still, with the changing epidemiology of invasive Hi, continued surveillance of all Hi strains is justified.

Characteristics of Haemophilus influenzae invasive isolates from Portugal following routine childhood vaccination against H. influenzae serotype b (2002-2010)

We aimed to characterize Haemophilus influenzae invasive isolates recovered in Portugal over a 9-year period (2002-2010) following the inclusion of H. influenzae serotype b (Hib) conjugate vaccination in the National Immunization Program (NIP) in the year 2000 and compare the results with those obtained in a similar study from the pre-vaccination era (1989-2001) previously described by us. As part of a laboratory-based passive surveillance system, 144 invasive isolates obtained in 28 Portuguese hospitals were received at the National Reference Laboratory for Bacterial Respiratory Infections and were characterized. Capsular types and antibiotic susceptibility patterns were determined. The ftsI gene encoding PBP3 was sequenced for β-lactamase-negative ampicillin-resistant (BLNAR) isolates. Genetic relatedness among isolates was examined by multilocus sequencing typing (MLST). Most isolates (77.1%) were non-capsulated, a significant increase compared to the pre-vaccination era (19.0%, p < 0.001). Serotype b strains decreased significantly (from 81.0 to 13.2%, p < 0.001) and serotype f increased significantly (from 0.8 to 6.9%, p = 0.03). Ten percent of the isolates were β-lactamase producers, a value lower than that previously observed (26.9%, p = 0.005). Eight percent of all isolates were BLNAR. A high genetic diversity among non-capsulated isolates was found. By contrast, capsulated isolates were clonal. The implementation of Hib vaccination has resulted in a significant decline in the proportion of serotype b H. influenzae invasive disease isolates. Most episodes of invasive disease occurring in Portugal are now due to fully susceptible, highly diverse, non-capsulated strains. Given the evolving dynamics of this pathogen and the increase in non-type b capsulated isolates, continuous surveillance is needed.

Haemophilus influenzae serotype f as a rare cause of septic arthritis

Non-type B Haemophilus influenzae emerges as a new pathogen in the post H. influenzae serotype b vaccine era. We describe a case of polyarticular septic arthritis caused by H. influenzae serotype f in an adult. The patient was successfully treated with surgical debridement and antibiotic. To the best of our knowledge, this is the fourth reported case of H. influenzae serotype f septic arthritis in adults.

Bacterial respiratory pathogens in children with inherited immune and airway disorders: nasopharyngeal carriage and disease risk

Children with primary immunodeficiencies, sickle cell disease and cystic fibrosis are at risk to develop invasive bacterial infections caused by respiratory tract pathogens, in particular Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus. This review article evaluates the role of nasopharyngeal colonization by these pathogens in the high prevalence of respiratory and invasive infections in children with inherited disorders affecting the immune system or the respiratory tract. We conclude that respiratory and invasive diseases that occur in children with primary immunodeficiencies or sickle cell disease are probably a result of increased nasopharyngeal colonization rates compared with healthy children. However, when the inherited disorder is characterized by local airway abnormalities such as in cystic fibrosis, enhanced nasopharyngeal colonization does not seem to play a major role in invasive disease risk. As the evidence for the role of nasopharyngeal colonization in disease risk in these specific patient groups partly comes from experimental studies and animal models, longitudinal studies in children are needed. Detailed understanding of the effect of colonization on the development of respiratory and invasive infections in children with primary immunodeficiencies, sickle cell disease or cystic fibrosis provides a justification for the selective introduction of vaccination and prophylactic antibiotic treatment. Recommendations for the use of (preventive) therapeutic strategies in these patient groups taking into account disease-specific immunologic mechanisms underlying colonization and disease are described.

Haemophilus influenzae acute endometritis with bacteremia: case report and literature review

Haemophilus influenzae rarely causes acute endometritis and the few published cases have always been associated with intrauterine devices (IUD). A 48-year-old female presented to the emergency department with a 3-day history of lower abdominal pain and fever. On physical examination she was tachycardic, hypotensive and had fundic tenderness to palpation. Imaging showed uterine leiomyomas and no IUD. Blood cultures grew a non-typable H. influenzae. Endometrial biopsy demonstrated acute endometritis. Tissue Gram stains and cervico-vaginal cultures were negative; however, polymerase chain reaction (PCR) determined presence of H. influenzae on the formalin-fixed, paraffin-embedded tissue biopsy. Evidence of H. influenzae in the endometrium demonstrates that the uterus can be the nidus for sepsis when invasive H. influenzae is found with no distinct usual primary focus. This case underscores the importance pathologic diagnosis and molecular testing.

Invasive Haemophilus influenzae in the United States, 1999-2008: epidemiology and outcomes

OBJECTIVES

Introduction of the Haemophilus influenzae type b (Hib) conjugate vaccine has resulted in a dramatic reduction of Hib disease in the U.S. and an increase in the relative importance of infections caused by nontypeable strains. The current project describes the characteristics and clinical outcomes of pediatric and adult patients with invasive H. influenzae (HI) and, through multivariable analysis, identifies risk factors for in-hospital mortality.

METHODS

HI cases were identified during 1999-2008 through active surveillance as part of active bacterial core surveillance (ABCs). Multivariable analysis was performed with logistic regression to identify factors predictive of in-hospital death.

RESULTS

4839 cases of HI were identified from 1999-2008. Children accounted for 17.1% of cases and adults 82.9%. Underlying conditions were present in 20.7% of children and 74.8% of adults. In-hospital mortality was highest in cases ≥65 years (21.9%) and <3 months (16.2%). The risk of in-hospital death in children <1 year was higher among those who were prematurely-born (<28 weeks, OR 7.1, 95% CI 3.2-15.6; 28-36 weeks OR 2.1, 95% CI 0.9-4.8) and, among children aged 1-17 years, higher in those with healthcare-associated onset and dialysis (OR 5.66, 95% CI 1.84-17.39; OR 18.11, 95% CI 2.77-118.65). In adults, age ≥40 was associated with death in nontypeable, but not encapsulated, infections. Infections with nontypeable strains increased the risk of death in cases ≥65 years (OR 1.81, 95% CI 1.31-2.52). Healthcare-associated HI, bacteremia without identifiable focus, bacteremic pneumonia, associated cirrhosis, cerebrovascular accident, dialysis, heart failure, and non-hematologic malignancy also increased the risk of death in adults.

CONCLUSION

Prematurity in infants, advanced age and certain chronic diseases in adults were associated with an increased risk of in-hospital death. Nontypeable HI was associated with higher mortality in the elderly.

Treatment of Haemophilus bacteremia with benzylpenicillin is associated with increased (30-day) mortality

BACKGROUND

Optimal antibiotic treatment strategies of Haemophilus infections are still needed. Therefore, 30-day case fatality rate (CFR) of Haemophilus bacteremia and efficacy of various antibiotic treatment regimes were studied.

METHODS

All episodes of Haemophilus bacteremia in the former Copenhagen County during the period 2000-9 were included in the study. Clinical and biochemical findings and outcome were collected retrospectively from medical records.

RESULTS

105 consecutive episodes were identified (median age: 69 years, with only 4 children <16 years), 72% were due to non-typeable -, 16% to typeable H. influenzae, and 11% to other Haemophilus species. Pneumonia was the most common primary focus (in 48%), and 58% of the patients had Charlson comorbidity index > 1. Definitive antibiotic therapy was in 26 cases benzylpenicillin, in 12 cases aminopenicillins, in 50 cases cefuroxime and in 16 cases broadspectrum antibiotics, whereas 1 palliative case died without start of therapy. Whereas the use of broadspectrum antibiotics was related to the severity of the disease (admittance to ICU, need for assisted ventilation or hemodialysis, septic shock), no significant difference in clinical features was demonstrated for therapy with benzylpenicillin, aminopenicillin or cefuroxime, except benzylpenicillin was rarely administered to immunosuppressed patients. The CFR was 22% (23/105). The choice of empiric antibiotic therapy was not significantly associated with mortality (adequate vs. inadequate treatment: 23% (21/93) vs. 17% (2/12), respectively, P > 0.05). In contrast, definite antibiotic therapy with cefuroxime or aminopenicillins resulted in a significantly lower CFR than treatment with benzylpenicillin (12% (6/50) or 0% (0/12) vs. 39% (10/26), respectively, Log rank test P < 0.02). When adjustments were made for other identified risk factors in bivariate logistic regression analysis, treatment with cefuroxime was still were found to be associated with a significantly lower CFR than for benzylpenicillin: OR: 0.21 (0.06-0.69), P = 0.01 (hospital-acquired bacteremia), OR: 0.27 (0.08-0.91), P = 0.04 (polymicrobial episodes), OR: 0.16 (0.04-0.59), P = 0.006 (admittance at intensive care unit), OR: 0.22 (0.06-0.82), P = 0.02 (alcohol abuse), OR: 0.15 (0.04-0.60), P = 0.008 (altered mental state), OR: 0.22 (0.07-0.71), P = 0.01 (temperature < 38 °C), OR: 0.23 (0.07-0.79), P = 0.02 (septic shock), OR: 0.21 (0.06-0.69), P = 0.01 (mechanical ventilation).

CONCLUSION

Our results suggest that, after susceptibility testing, cefuroxime or aminopenicillins are preferable to benzylpenicillins as definitive therapy for Haemophilus bacteremia.

Evolving epidemiology of invasive Haemophilus infections in the post-vaccination era: results from a long-term population-based study

Historically, Haemophilus influenzae (Hi) serotype b (Hib) caused most invasive Haemophilus infections worldwide, mainly in children. In 1989 routine childhood vaccination against Hib was initiated in Iceland. We conducted a population-based study of all patients in the country with Haemophilus spp. isolated from sterile sites (n = 202), from 1983 to 2008. Epidemiology, clinical characteristics of the infections and serotypes of the isolates were compared during the pre-vaccination (1983-1989) and post-vaccination era (1990-2008). Following the vaccination, the overall incidence of Hib decreased from 6.4 to 0.3/100,000 per year (p <0.05) whereas the incidence did not change significantly for infections caused by Haemophilus sensu lato not serotype b, hereafter referred to as non-type b Hi (0.9 vs 1.2, respectively). The most frequent diagnosis prior to 1990 was meningitis caused by Hib, which was subsequently replaced by pneumonia and bacteraemia caused by non-type b Hi. Most commonly, non-type b Hi were non-typeable (NTHi; 40/59), followed by Hi serotype f (14/59) and Hi serotype a (3/59). Pregnancy was associated with a markedly increased susceptibility to invasive Haemophilus infections (RR 25.7; 95% CI 8.0-95.9, p <0.0001) compared with non-pregnant women. The case fatality rate for Hib was 2.4% but 14% for non-type b Hi, highest at the extremes of age. Hib vaccination gives young children excellent protection and decreases incidence in the elderly due to herd effect in the community. Replacement with other species or serotypes has not been noted. Pregnant women are an overlooked risk group.

Haemophilus influenzae infections in the H. influenzae type b conjugate vaccine era

The widespread use of Haemophilus influenzae type b (Hib) conjugate vaccines has nearly eradicated invasive Hib disease where the vaccines are used. This success was accompanied by a shift in capsular serotypes of invasive H. influenzae disease, with nontypeable strains replacing type b strains as the most common bloodstream isolate, but there is no convincing evidence of a true increase in the incidence of non-serotype b invasive infections. H. influenzae causes predominantly mucosal infections. The introduction of vaccines for otitis media and global shifts in antimicrobial susceptibility emphasize the importance of continued surveillance of H. influenzae colonization and disease patterns.

Haemophilus influenzae type b infection, vaccination, and H. influenzae carriage in children in Minnesota, 2008-2009

An increase in invasive Haemophilus influenzae type b (Hib) cases occurred in Minnesota in 2008 after the recommended deferral of the 12-15 months Hib vaccine boosters during a US vaccine shortage. Five invasive Hib cases (one death) occurred in children; four had incomplete Hib vaccination (three refused/delayed); one was immunodeficient. Subsequently, we evaluated Hib carriage and vaccination. From 18 clinics near Hib cases, children (aged 4 weeks-60 months) were surveyed for pharyngeal Hib carriage. Records were compared for Hib, diphtheria-tetanus-acellular pertussis (DTaP), and pneumococcal (PCV-7) vaccination. Parents completed questionnaires on carriage risk factors and vaccination beliefs. In 1631 children (February-March 2009), no Hib carriage was detected; Hib vaccination was less likely to be completed than DTaP and PCV-7. Non-type b H. influenzae, detected in 245 (15%) children, was associated with: male sex, age 24-60 months, daycare attendance >15 h/week, a household smoker, and Asian/Pacific Islander race/ethnicity. In 2009, invasive Hib disease occurred in two children caused by the same strain that circulated in 2008. Hib remains a risk for vulnerable/unvaccinated children, although Hib carriage is not widespread in young children.