Non-type b Haemophilus influenzae disease: clinical and epidemiologic characteristics in the Haemophilus influenzae type b vaccine era

Molecular characterization of multidrug-resistant non-typeable Haemophilus influenzae with high-level resistance to cefuroxime, levofloxacin, and trimethoprim-sulfamethoxazole

BACKGROUND

Non-typeable Haemophilus influenzae (NTHi) has become the major cause of invasive H. influenzae diseases in the post-H. influenzae type b vaccine era. The emergence of multidrug-resistant (MDR) NTHi is a growing public health problem. Herein, we investigated the molecular basis of MDR in NTHi. The isolated NTHi were subjected to antimicrobial susceptibility testing for 12 agents. Whole genome and plasmid sequencing were conducted and analyzed to identify significant genetic variations and plasmid-encoded genes conferred antibiotic resistance.

RESULTS

Thirteen (50%) MDR NTHi isolates were obtained; of these, 92.3% were non-susceptible to ampicillin, 30.8% to amoxicillin-clavulanate, 61.5% to cefuroxime, 61.5% to ciprofloxacin/levofloxacin, 92.3% to trimethoprim-sulfamethoxazole, 30.8% to tetracycline, and 7.7% to azithromycin. Eight ampicillin-resistant isolates were β-lactamase positive; of these, 6 carried bla_TEM-1 and 2 carried bla_ROB-1, whereas 4 were β-lactamase negative. Genetic variations in mrdA, mepA, and pbpG were correlated with amoxicillin-clavulanate non-susceptibility, whereas variations in ftsI and lpoA conferred cefuroxime resistance. Five variations in gyrA, 2 in gyrB, 3 in parC, 1 in parE, and 1 in the parC-parE intergenic region were associated with levofloxacin/ciprofloxacin non-susceptibility. Among these genes, 8 variations were linked to high-level levofloxacin resistance. Six variations in folA were associated with trimethoprim-sulfamethoxazole resistance. Plasmid-bearing tet(B) and mef(A) genes were responsible for tetracycline and azithromycin resistance in 4 and 1 MDR isolates, respectively.

CONCLUSIONS

This study clarified the molecular epidemiology of MDR in NTHi. This can benefit the monitoring of drug resistance trends in NTHi and the adequate medical management of patients with NTHi infection.

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

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

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.

Nontypeable Haemophilus influenzae Otitis Media: Mastoiditis and Meningitis Complicated with Central Venous Thrombosis in an Immunocompetent Child

Implementation of the Haemophilus influenzae type B (Hib) conjugate vaccine brought about a reduction in the number of cases and morbidity from type B but an increase in nontypeable strain infections. Nontypeable Haemophilus influenzae (NTHi) commonly colonizes children's upper respiratory tract and causes otitis media, sinusitis, and bronchitis. Invasive NTHi diseases, such as meningitis and septicemia, have rarely been reported. Herein, we discuss a previously healthy, fully immunized 3-year-old girl presented with otitis media and mastoiditis leading to meningitis caused by NTHi complicated with central venous thrombosis. She was treated with antibiotics, mastoidectomy and ventilation tube insertion, and anticoagulation therapy and recovered uneventfully. Through this case, we wish to share our unique clinical experience that NTHi should be born in mind as a potential pathogen that can cause meningitis in previously healthy children, which may be helpful in future cases.

Recurrent Meningitis Caused by β-Lactamase-Positive Amoxicillin/Clavulanate-Resistant Non-Typeable Haemophilus influenzae in a Child with an Inner Ear Malformation: A Case Report

Infections with Haemophilus influenzae type b have been decreasing due to widespread use of conjugate vaccines thereto, and there has been an increasing trend in the relative proportion of invasive infections by non-typeable H. influenzae (NTHi). NTHi commonly colonizes the upper respiratory tract and causes recurrent infections of the adjacent organs. There is a rapid development of antibiotic resistance in NTHi strains, and therefore it is important to select appropriate antibiotics for treatment. We report a case of recurrent NTHi meningitis in a 5-year-old girl with a previous history of recurrent otitis media. The patient presented with fever accompanying recurrent vomiting, and β-lactamase-positive amoxicillin/clavulanate-resistant NTHi was isolated in cerebrospinal fluid culture. Antibiotic resistance testing revealed penicillin-binding protein 3 mutation, which is an important emerging mechanism of antibiotic resistance of NTHi. Cystic cochleovestibular malformation was also identified, which may be the predisposing condition for recurrent otitis media, and invasive NTHi infection. Acute symptoms resolved with antibiotic therapy (cefotaxime, 200 mg/kg per day). After surgical revision, the patient has been in good health without recurrence. In children with recurrent respiratory tract infections, or invasive NTHi infection, it is important to consider the presence of underlying diseases and infections due to antibiotic resistant pathogens, in order to select an appropriate antibiotic agent for treatment.

Fatal, Fulminant and Invasive Non-Typeable Haemophilus influenzae Infection in a Preterm Infant: A Re-Emerging Cause of Neonatal Sepsis

Early-onset neonatal sepsis (EOS) is a major cause of neonatal death and long-term neurodevelopmental disabilities among survivors. The common pathogens causing EOS are group B streptococcus (GBS) and Escherichia coli. Haemophilus influenzae (H.influenzae) is a Gram-negative coccobacillus that can cause severe invasive disease and can be divided into either typeable or non-typeable strains. H.influenzae serotype b (Hib) is the most virulent and the major cause of bacterial meningitis in young children prior to routine immunization against Hib. Hib infection rates have dramatically reduced since then. However, a number of studies have reported an increasing incidence of non-typeable H. influenzae (NTHi) sepsis in neonates worldwide and concluded that pregnant women may have an increased risk to invasive NTHi disease with poor pregnancy outcomes. We present a case of fulminant neonatal sepsis caused by NTHi in an extremely preterm infant and discuss potential preventative measures to reduce its re-emergence.

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

Background

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

Case Presentation

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

Conclusions

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

Vaccine-preventable child deaths in New South Wales from 2005 to 2014: How much is preventable?

AIM

To identify and describe potentially vaccine-preventable child deaths in New South Wales (NSW).

METHODS

Child deaths in NSW from 2005 to 2014 potentially preventable by vaccination were identified from the NSW Child Death Register (maintained by the NSW Ombudsman) and the Notifiable Conditions Information Management System (NSW Health). Medical and post-mortem records were reviewed. Cases were classified as vaccine-preventable based on the strength of evidence for the relevant infection causing death and likelihood that death was preventable through vaccination. A two-source capture-recapture method was used to estimate the true number of deaths. Age-specific mortality rate and number of deaths by disease, area of residence and comorbidity were analysed. Deaths were classified as preventable based on vaccine availability, eligibility under the National Immunisation Program, age and presence of any contraindications.

RESULTS

Fifty-four deaths were identified as definitely or probably due to diseases for which a vaccine was available, with a total average annual mortality rate of 0.33 per 100 000 children and 2.1 per 100 000 infants. Two thirds of deaths occurred in children with no identified comorbidities. Twenty-three deaths were classified as preventable or potentially preventable by vaccination, with influenza (12 deaths) and meningococcal disease (five deaths) most common. An additional 15 deaths would be potentially preventable as of August 2016 due to immunisation recommendation changes including maternal vaccination.

CONCLUSION

Maternal vaccination along with increased uptake of childhood influenza vaccination could reduce child deaths, particularly from influenza.

Non-Type b Haemophilus influenzae Septic Arthritis in Children

Invasive disease caused by non-type b Haemophilus influenzae serotypes has been increasingly reported. Although to date it has been a rarely described cause of septic arthritis, we present 10 cases of non-type b H influenzae septic arthritis in children seen in a tertiary care center that serves a large Native American population.

Effect of 10-valent pneumococcal conjugate vaccine on nasopharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae among children in São Paulo, Brazil

In March 2010, Brazil introduced the 10-valent pneumococcal conjugate vaccine (PCV10) in the routine infant immunization program using a 4-dose schedule and catch-up for children <23months. We investigated PCV10 effect on nasopharyngeal carriage with vaccine-type Streptococcus pneumoniae (Spn) and non-typeable Haemophilus influenzae (NTHi) among children in São Paulo city. Cross-sectional surveys were conducted in 2010 (baseline) and 2013 (post-PCV10). Healthy PCV-naïve children aged 12-23months were recruited from primary health centers during immunization campaigns. Nasopharyngeal swabs were collected and tested for Hi; for Spn, all baseline and a stratified random sample of 400 post-PCV10 swabs were tested. We compared vaccine-type Spn and NTHi carriage prevalence pre-/post-PCV10, and used logistic regression to estimate PCV10 effectiveness (1-adjusted odds ratio×100%). Overall 501 children were included in the baseline and 1167 in the post-PCV10 survey (including 400 tested for Spn). Spn was detected in 40.3% of children at baseline and 48.8% post-PCV10; PCV10 serotypes were found in 19.8% and 1.8% respectively, representing a decline of 90.9% (p<0.0001). Carriage of vaccine-related serotypes increased (10.8-21.0%, p<0.0001), driven primarily by a rise in serotype 6C (1.8-11.2%, p<0.0001); carriage of serotypes 6A and 19A did not significantly change. PCV10 effectiveness (4 doses) against vaccine-type carriage was 97.3% (95% confidence interval 88.7-99.3). NTHi prevalence increased from 26.0% (130/501) to 43.6% (509/1167, p<0.0001); PCV10 vaccination seemed significantly associated with NTHi carriage, even after adjusting for other known risk factors. Carriage with PCV10 serotypes among toddlers declined dramatically following PCV10 introduction in São Paulo, Brazil. No protection of PCV10 against NTHi was observed. Our findings contribute to a growing body of evidence of PCV10 impact on vaccine-type carriage and highlight the importance of PCV10 as a tool to reduce the burden of pneumococcal disease in Brazil and globally.

Genital carriage of the genus Haemophilus in pregnancy: species distribution and antibiotic susceptibility

Recent reports have hypothesized that colonization of the maternal genital tract with non-capsulated Haemophilus influenzae could result in neonatal invasive disease. In this study, genital carriage of the genus Haemophilus was investigated in 510 pregnant women attending an Italian hospital for routine controls. Overall, vaginal carriage of the genus Haemophilus was 9.0 % (46/510). A high colonization rate with Haemophilus parainfluenzae (37/510, 7.3 %) was found; other species, such as Haemophilus pittmaniae (7/510, 1.4 %) and Haemophilus haemolyticus (2/510, 0.4 %), were detected for the first time in the genital flora by 16S rRNA gene sequencing. Notably, no H. influenzae was identified, in agreement with previous investigations indicating that this species is rarely isolated from the genito-urinary tract of pregnant women. No antibiotic resistance was detected in H. pittmaniae and H. haemolyticus, but quite a high degree of ampicillin (10/37, 27 %) and ciprofloxacin (3/37, 8.1 %) resistance was observed in H. parainfluenzae. Five ampicillin-resistant isolates were β-lactamase producers, whereas five isolates exhibited a β-lactamase-negative ampicillin-resistant (BLNAR) phenotype. Sequencing of penicillin-binding protein 3 revealed that Val511Ala, Asn526Ser, Ala530Ser and Thr574Ala changes were associated with BLNAR phenotypes. Two ciprofloxacin-resistant isolates carried substitutions in both GyrA (Ser84Phe and Asp88Tyr) and ParC (Ser84Tyr and Met198Leu); the other ciprofloxacin-resistant isolate had substitutions in ParC, only (Ser138Thr and Met198Leu). In conclusion, ∼10 % of pregnant women carried a species of Haemophilus in their genital tract. The emergence of non-β-lactamase-mediated resistance in genital H. parainfluenzae is a matter of concern because of the risk of mother-to-baby transmission.

Neonatal invasive Haemophilus influenzae disease in England and Wales: epidemiology, clinical characteristics, and outcome

BACKGROUND

Nontypeable Haemophilus influenzae (NTHi) frequently causes noninvasive upper respiratory tract infections in children but can cause invasive disease, mainly in older adults. An increased burden of invasive NTHi disease in the perinatal period has been reported by a number of studies. Here we describe the epidemiology, clinical characteristics, and outcome of neonatal invasive H. influenzae disease in England and Wales over a 5-year period.

METHODS

Public Health England conducts enhanced national surveillance of invasive H. influenzae disease in England and Wales. Detailed clinical information was obtained for all laboratory-confirmed cases in infants aged ≤31 days during 2009-2013.

RESULTS

Overall, 118 live-born neonates had laboratory-confirmed invasive H. influenzae disease: 115 (97%) were NTHi, 2 were serotype f, and 1 was serotype b. NTHi was isolated within 48 hours of birth (early-onset) in 110 of 115 (96%) cases, and 70 of 110 (64%) presented with septicemia. Only 17 mothers (15%) had suspected bacterial infection requiring antibiotics during labor. Few (8/110 [7%]) neonates had comorbidities. The incidence of early-onset NTHi increased exponentially with prematurity, from 0.9 per 100 000 (95% confidence interval [CI], .6-1.4) in term neonates to 342 per 100 000 (95% CI, 233.9-482.7) in neonates born at <28 weeks' gestation (incidence rate ratio, 365 [95% CI, 205-659]; P < .001). Case fatality for early-onset NTHi was 19% (21/110); each additional gestational week reduced the odds of dying by 21% (odds ratio, 0.79 [95% CI, .69-.90]; P < .01). A quarter of neonates who survived experienced long-term complications.

CONCLUSIONS

Early-onset neonatal NTHi disease is strongly associated with premature birth and causes significant morbidity and mortality.

Non-typeable Haemophilus influenzae, an under-recognised pathogen

Non-typeable Haemophilus influenzae (NTHi) is a major cause of mucosal infections such as otitis media, sinusitis, conjunctivitis, and exacerbations of chronic obstructive pulmonary disease. In some regions, a strong causal relation links this pathogen with infections of the lower respiratory tract. In the past 20 years, a steady but constant increase has occurred in invasive NTHi worldwide, with perinatal infants, young children, and elderly people most at risk. Individuals with underlying comorbidities are most susceptible and infection is associated with high mortality. β-lactamase production is the predominant mechanism of resistance. However, the emergence and spread of β-lactamase-negative ampicillin-resistant strains in many regions of the world is of substantial concern, potentially necessitating changes to antibiotic treatment guidelines for community-acquired infections of the upper and lower respiratory tract and potentially increasing morbidity associated with invasive NTHi infections. Standardised surveillance protocols and typing methodologies to monitor this emerging pathogen should be implemented. International scientific organisations need to raise the profile of NTHi and to document the pathobiology of this microbe.

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.

Fatal Haemophilus influenzae type a sepsis in an infant

Haemophilus influenzae type a can cause severe sepsis, as demonstrated by the case described. Epidemiology of sepsis in childhood is changing. Regardless of the pathogen involved, management of children with septic shock involves resuscitative measures and empiric antibiotics. The following case of H. influenzae type a sepsis proved fatal in spite of appropriate therapy.

Invasive Haemophilus influenzae serotype e and f disease, England and Wales

Incidence of serotype e was 3-fold lower than serotype f, but it caused more severe clinical disease.

Haemophilus influenzae serotype b and a capsule-deficient type mutant (b-) invasive disease in a partially vaccinated child in Brazil

We report a rare case of infection by two different types of Haemophilus influenzae strains in a child who received only one dose of the H. influenzae serotype b (Hib) conjugate vaccine (DTwP+Hib). The strains were recovered from blood and cerebrospinal fluid (CSF) and were phenotypically identified as Hib and non-typable H. influenzae, respectively, after serological tests. The two strains were characterized by PCR capsular typing, multilocus sequence typing and PFGE. Our results suggest that the infection was caused by the bloodstream invasion by a single Hib strain, followed by the diffusion of the bacteria across the blood-brain barrier and into the CSF. The strain recovered from the CSF, however, was identified as a capsule-deficient type mutant (b(-)) strain. Despite the high efficacy of the Hib conjugate vaccine, the increase in the numbers of strains able to escape the immune system of the vaccinated population advocates continued surveillance.

Haemophilus influenzae Sepsis and Placental Abruption in an Unvaccinated Immigrant

Background

Haemophilus influenzae infections have declined dramatically in the United States since implementation of the conjugate vaccine. However, in countries where widespread immunization is not routine, H influenzae remains a significant cause of morbidity and mortality. We report a case of a previously unvaccinated immigrant with confirmed H influenzae sepsis and placental abruption leading to spontaneous abortion.

Objectives

To alert emergency medicine practitioners that H influenzae should be recognized as a maternal, fetal, and neonatal pathogen. Clinicians should consider this diagnosis in immigrants presenting with uncertain vaccination history, as H influenzae can cause significant morbidity and mortality.

Case Presentation

A 36-year-old female was referred to our emergency department (ED) with lower abdominal pain with some vaginal spotting. The patient had an initial visit with normal laboratory investigations and normal imaging results, with complete resolution of symptoms. The patient returned to the ED with sudden onset of vaginal bleeding and abdominal pain. She presented at this time with sepsis, which progressed to septic shock, causing placental abruption and ultimately, spontaneous abortion. The patient was treated with pressors and antibiotics and was admitted to the medical intensive care unit where she received ampicillin, gentamycin, and clindamycin for suspected chorioamnionitis. The patient's blood cultures came back positive after 1 day for H influenzae. The patient did well and was discharged from the hospital 4 days later.

Conclusion

Haemophilus influenzae should be recognized as a neonatal and maternal pathogen. Clinicians should consider this diagnosis in immigrants presenting with uncertain vaccination history, especially in pregnant females, as H influenzae can cause significant morbidity and mortality.

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.

The burden of nonencapsulated Haemophilus influenzae in children and potential for prevention

PURPOSE OF REVIEW

In countries with established Haemophilus influenzae serotype b (Hib) immunization programmes, nonencapsulated H. influenzae (ncHi) is responsible for most invasive H. influenzae infections across all age groups and is associated with higher case fatality. A pneumococcal conjugate vaccine has recently been licensed, which may potentially also protect against invasive H. influenzae infections.

RECENT FINDINGS

Invasive ncHi disease is uncommon in childhood but has a much higher incidence in the first month of life. Most neonates with invasive ncHi infections are born prematurely and develop septicaemia in the first 48 h of life which can be fatal. After this period, invasive ncHi incidence falls rapidly and remains low throughout childhood. Most infants and children who develop invasive ncHi disease have significant underlying comorbidities, particularly neurological disease, malignancy and other conditions requiring immunosuppressive therapy. Although characteristically associated with respiratory tract infections, at least a quarter of invasive ncHi infections present with meningitis.

SUMMARY

A vaccine against ncHi could have an important preventive role in children with comorbidities. Future studies should focus on assessing specific risk factors for neonatal and childhood ncHi disease and long-term outcomes of children with invasive ncHi meningitis.

Health and economic impact of PHiD-CV in Canada and the UK: a Markov modelling exercise

OBJECTIVE

The spectrum of diseases caused by Streptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi) represents a large burden on healthcare systems around the world. Meningitis, bacteraemia, community-acquired pneumonia (CAP), and acute otitis media (AOM) are vaccine-preventable infectious diseases that can have severe consequences. The health economic model presented here is intended to estimate the clinical and economic impact of vaccinating birth cohorts in Canada and the UK with the 10-valent, pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) compared with the newly licensed 13-valent pneumococcal conjugate vaccine (PCV-13).

METHODS

The model described herein is a Markov cohort model built to simulate the epidemiological burden of pneumococcal- and NTHi-related diseases within birth cohorts in the UK and Canada. Base-case assumptions include estimates of vaccine efficacy and NTHi infection rates that are based on published literature.

RESULTS

The model predicts that the two vaccines will provide a broadly similar impact on all-cause invasive disease and CAP under base-case assumptions. However, PHiD-CV is expected to provide a substantially greater reduction in AOM compared with PCV-13, offering additional savings of Canadian $9.0 million and £4.9 million in discounted direct medical costs in Canada and the UK, respectively.

LIMITATIONS

The main limitations of the study are the difficulties in modelling indirect vaccine effects (herd effect and serotype replacement), the absence of PHiD-CV- and PCV-13-specific efficacy data and a lack of comprehensive NTHi surveillance data. Additional limitations relate to the fact that the transmission dynamics of pneumococcal serotypes have not been modelled, nor has antibiotic resistance been accounted for in this paper.

CONCLUSION

This cost-effectiveness analysis suggests that, in Canada and the UK, PHiD-CV's potential to protect against NTHi infections could provide a greater impact on overall disease burden than the additional serotypes contained in PCV-13.

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.

The impact of Haemophilus influenzae serotype B resurgence on the epidemiology of childhood invasive Haemophilus influenzae disease in England and Wales

This study describes the epidemiology of childhood invasive Haemophilus influenzae disease in England and Wales between 1994 and 2008. H. influenzae serotype b incidence was lowest in 1998 (0.26/100,000), rising to 1.8/100,000 in 2002 before falling to 0.27/100,000 in 2008. During this period, nontype b H. influenzae disease remained stable, but there was a small year-on-year increase (3.4%/y; 95% CI: 1.4-5.5%) in incidence.

Changes in serotype distribution of Haemophilus influenzae meningitis isolates identified through laboratory-based surveillance following routine childhood vaccination against H. influenzae type b in Brazil

Following routine childhood vaccination against Haemophilus influenzae type b (Hib) disease in Brazil in 1999, passive laboratory surveillance reported increasing numbers of non-b serotypes and nontypeable H. influenzae (NTHi) from meningitis cases. To characterize this increase, we analyzed data on 3910 H. influenzae isolated from cerebrospinal fluid or blood from meningitis cases that were sent to the national reference laboratory for serotyping from 1990 to 2008. Hib accounted for 98% of H. influenzae meningitis isolates received during 1990-1999 versus 59% during 2000-2008, while non-b serotypes increased from 1% to 19% and NTHi increased from 2% to 22% of H. influenzae isolates received during the two periods. Higher proportions of non-b serotypes and NTHi than Hib were isolated from blood rather than cerebrospinal fluid. Estimated incidence rates for H. influenzae meningitis for Sao Paulo state remained below 1 case per million population during 2000-2008, although annual incidence of NTHi meningitis (mean, 0.03 cases per 100,000 population) increased in several age groups. Changes in surveillance for H. influenzae following introduction of Hib conjugate vaccine likely contributed to increased numbers of non-b and nontypeable H. influenzae meningitis isolates received at the national reference laboratory.

Microbiology of bronchoalveolar lavage fluid in children with acute nonresponding or recurrent community-acquired pneumonia: identification of nontypeable Haemophilus influenzae as a major pathogen

Background. Precise etiologic diagnosis in pediatric community-acquired pneumonia (CAP) remains challenging.

Methods. We conducted a retrospective study of CAP etiology in 2 groups of pediatric patients who underwent flexible bronchoscopy (FOB) with bronchoalveolar lavage (BAL); children with acute nonresponsive CAP (NR-CAP; n = 127) or recurrent CAP (Rec-CAP; n = 123). Procedural measures were taken to limit contamination risk and quantitative bacterial culture of BAL fluid (significance cutoff point, ≥10⁴ colony-forming units/mL) was used. Blood culture results, serological test results, nasopharyngeal secretion findings, and pleural fluid culture results were also assessed, where available.

Results. An infectious agent was detected in 76.0% of cases. In 51.2% of infections, aerobic bacteria were isolated, of which 75.0%, 28.9%, and 13.3% were Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae, respectively. Most (97.9%) of the H. influenzae strains were nontypeable (NTHi). H. influenzae was detected in 26.0% of NR-CAP cases and 51.2% of Rec-CAP cases, whereas Mycoplasma pneumoniae was the predominant pathogen in the NR-CAP group (accounting for 34.9% of cases) but not in the Rec-CAP group (19.3%). Viruses were found in 30.4% of cases, with respiratory syncytial virus, parainfluenzaviruses, and influenzaviruses detected most frequently. Mixed infections were found in 18.9% of NR-CAP cases and 30.1% of Rec-CAP cases.

Conclusions. A variety of microorganisms were isolated with frequent mixed infection. NTHi was one of the major pathogens found, especially in association with recurrent CAP, possibly because of improved detection with the FOB with BAL procedure. This suggests that the burden of pediatric CAP could be reduced by addressing NTHi as a major causative pathogen.

Symptoms and signs differentiating croup and epiglottitis

AIM

To determine differentiating symptoms and signs of epiglottitis and laryngotracheobronchitis (croup).

METHODS

Contemporaneous interview of parents and clinical examination of children with acute upper airway obstruction presenting to the intensive care unit of a paediatric hospital.

RESULTS

Two hundred and three children were examined over a 40-month period. One hundred and two had croup, of whom 49 had the diagnosis confirmed at intubation and another six by direct laryngeal inspection without intubation. One hundred and one had epiglottitis of whom 95 were diagnosed by direct inspection of the larynx at intubation, five by a lateral X-ray of the neck and one on direct inspection without intubation. One child with epiglottitis died. Although both illnesses presented with stridor, the additional presence of drooling had a high sensitivity (0.79, 95% CI 0.70-0.86) and specificity (0.94, 95% CI 0.88-0.97) for epiglottitis while coughing had a high sensitivity (1.00, 95% CI 0.96-1.00) and high specificity (0.98, 95% CI 0.93-0.99) for croup. Coughing predicted croup but drooling predicted epiglottitis. Additional reliable signs of epiglottitis were a preference to sit, refusal to swallow and dysphagia. Thirty-seven percent of children with epiglottitis and 16% with croup were treated as having another respiratory illness at least once before definitive diagnosis.

CONCLUSIONS

Epiglottitis and croup are often confused because they share symptoms and signs including stridor. However, differentiation in early illness is possible by additional observation of coughing and absence of drooling in croup and by the additional observation of drooling with absence of coughing in epiglottitis.

Invasive disease caused by Haemophilus influenzae type a in Northern Ontario First Nations communities

Seven epidemiologically unrelated cases of invasive Haemophilus influenzae type a (Hia) disease were identified in First Nations communities of Northwestern Ontario, Canada, in 2004–2008. In all cases, Hia was isolated from blood. The clinical presentation in most of the cases was moderately severe and all patients responded to antibiotic therapy. Laboratory analysis of Hia isolates from Northwestern Ontario indicated striking similarities in their phenotypic and genotypic characteristics. The findings are discussed in the context of current epidemiology of invasive Hia disease. Our data along with some published studies by others suggest an increased susceptibility to this infection among North American indigenous populations.

Meningitis and septicemia caused by nontypeable Haemophilus influenzae in a previously healthy 2-year-old girl

Nontypeable Haemophilus influenzae (NTHi) commonly colonizes the upper respiratory tract of children and causes otitis media, sinusitis, and bronchitis. Invasive NTHi diseases such as meningitis and septicemia have rarely been reported, especially in children with underlying predisposing conditions such as head trauma and immune compromise. However, we report a previously healthy 2-year-old girl who developed meningitis and septicemia caused by NTHi biotype ΙΙΙ. She was treated with dexamethasone, meropenem, and ceftriaxone, and recovered uneventfully. We wish to emphasize that NTHi should be borne in mind as a potential pathogen that can cause meningitis and septicemia, even in previously healthy children.

Invasive Haemophilus influenzae Disease, Europe, 1996-2006

An international collaboration was established in 1996 to monitor the impact of routine Haemophilus influenzae type b (Hib) vaccination on invasive H. influenzae disease; 14 countries routinely serotype all clinical isolates. Of the 10,081 invasive H. influenzae infections reported during 1996-2006, 4,466 (44%, incidence 0.28 infections/100,000 population) were due to noncapsulated H. influenzae (ncHi); 2,836 (28%, 0.15/100,000), to Hib; and 690 (7%, 0.036/100,000), to non-b encapsulated H. influenzae. Invasive ncHi infections occurred in older persons more often than Hib (median age 58 years vs. 5 years, p<0.0001) and were associated with higher case-fatality ratios (12% vs. 4%, p<0.0001), particularly in infants (17% vs. 3%, p<0.0001). Among non-b encapsulated H. influenzae, types f (72%) and e (21%) were responsible for almost all cases; the overall case-fatality rate was 9%. Thus, the incidence of invasive non-type b H. influenzae is now higher than that of Hib and is associated with higher case fatality.

Serotype distribution and beta-lactam resistance in Haemophilus influenzae isolated from patients with respiratory infections in Korea

Haemophilus influenzae is a frequent causative bacterial pathogen of respiratory tract infections. Resistance to beta-lactam antibiotics has been a significant clinical problem in treatment for H. influenzae respiratory infections. This study describes the serotype, antibiotic resistance and distribution of TEM-1 or ROB-1 beta-lactamase in H. influenzae isolates from local private hospitals from 2002 to 2004. Among the 100 H. influenzae respiratory isolates, only 7% were identified as serotypes a, b, e, and f, with the remaining 93% being nontypeable. Resistance to ampicillin, cefaclor, and tetracycline was 57%, 46%, and 16%, respectively. All strains were susceptible to azithromycin and ciprofloxacin, whereas amoxicillin/clavulanate, cefotaxime, and imipenem exhibited reduced susceptibilities of 99%, 99%, and 91%, respectively. All 57 ampicillin-resistant strains (minimum inhibitory concentration, MIC>or=4 microg/ml) were beta-lactamase-positive and possessed the TEM-1 type beta-lactamase. One beta-lactamase-positive amoxicillin/clavulanate-resistant isolate that was resistant to ampicillin (MIC>128 microg/ml) had the TEM-1 type beta-lactamase and not susceptible to cefaclor and cefotaxime. Analysis of penicillin binding protein 3 revealed six residues (Asp-350, Met-377, Ala-502, Asn-526, Val-547, and Asn-569) that were substituted by Asn, Ile, Val, Lys, Ile, and Ser, respectively.

Maternal and neonatal sepsis caused by Haemophilus influenzae type d

A 29-year-old pregnant woman was admitted to hospital with signs of sepsis and threatened pre-term labour. The premature neonate also showed signs of sepsis. Haemophilus influenzae biotype III was cultured from a midstream urine sample taken from the mother, maternal placental swabs and neonatal blood cultures. The placental and neonatal isolates were both found to be serotype d by PCR, and were indistinguishable by PFGE.

Genotypic characteristics of Haemophilus influenzae isolates from pediatric pneumonia patients in Chengdu city, Sichuan, China

Two hundred and seventy-three Haemophilus influenzae strains isolated from pediatric pneumonia patients in China were studied. We used Multilocus Sequence Typing (MLST) to analyze genotypic characteristics. All strains were biotyped and serotyped. Relatedness and patterns of genes among isolates were determined by the analysis of MLST and eBURST. H. influenzae primarily causes acute pneumonia in children under 1 year old. Nontypeable H. influenzae was responsible for most cases of pediatric pneumonia. All 273 strains were classified into eight biotypes. They mostly belonged to the I, II, and III biotypes (17.6%, 43.6%, and 22.7%, respectively). 62 strains (22.7%) produced beta-lactamase. We found 28 novel alleles. Fifty different STs were found by MLST, of which 39 were novel. These were ST477 through ST508 and ST521 through ST527. Group 17 and predicted founders 503 were new groups in this study. No STs correlated with strains from Korea, which is adjacent to China. The H. influenzae strains from China appeared to have heterogeneous ST types patterns which may be the reason no outbreaks or epidemics of H. influenzae infections have occurred in Chengdu city, Sichuan, China.

Diagnostic clinical and laboratory findings in response to predetermining bacterial pathogen: data from the Meningitis Registry

Background

Childhood Meningitis continues to be an important cause of mortality in many countries. The search for rapid diagnosis of acute bacterial meningitis has lead to the further exploration of prognostic factors. This study was scheduled in an attempt to analyze various clinical symptoms as well as rapid laboratory results and provide an algorithm for the prediction of specific bacterial aetiology of childhood bacterial meningitis.

Methodology and Principal Findings

During the 32 year period, 2477 cases of probable bacterial meningitis (BM) were collected from the Meningitis Registry (MR). Analysis was performed on a total of 1331 confirmed bacterial meningitis cases of patients aged 1 month to 14 years. Data was analysed using EPI INFO (version 3.4.3-CDC-Atlanta) and SPSS (version 15.0 - Chicago) software. Statistically significant (p<0.05) variables were included in a conditional backward logistic regression model. A total of 838 (63.0%) attributed to Neisseria meningitidis, 252 (18.9%) to Haemophilus influenzae, 186 (14.0%) to Streptococcus pneumoniae and 55 (4.1%) due to other bacteria. For the diagnosis of Meningococcal Meningitis, the most significant group of diagnostic criteria identified included haemorrhagic rash (OR 22.36), absence of seizures (OR 2.51), headache (OR 1.83) and negative gram stain result (OR 1.55) with a Positive Predictive Value (PPV) of 96.4% (95%CI 87.7–99.6). For the diagnosis of Streptococcus pneumoniae, the most significant group of diagnostic criteria identified included absence of haemorrhagic rash (OR 13.62), positive gram stain (OR 2.10), coma (OR 3.11), seizures (OR 3.81) and peripheral WBC≥15000/µL (OR 2.19) with a PPV of 77.8% (95%CI 40.0–97.2). For the diagnosis of Haemophilus influenzae, the most significant group of diagnostic criteria included, absence of haemorrhagic rash (OR 13.61), age≥1year (OR 2.04), absence of headache (OR 3.01), CSF Glu<40 mg/dL (OR 3.62) and peripheral WBC<15000/µL (OR 1.74) with a PPV of 58.5% (95%CI 42.1–73.7).

Conclusions

The use of clinical and laboratory predictors for the assessment of the causative bacterial pathogen rather than just for predicting outcome of mortality seems to be a useful tool in the clinical management and specific treatment of BM. These findings should be further explored and studied.

Clinical characteristics of Haemophilus influenzae meningitis in Denmark in the post-vaccination era

The introduction of Haemophilus influenzae type b (Hib) vaccine into the Danish childhood vaccination programme in 1993 may have influenced the epidemiology of H. influenzae meningitis (i.e. increasing frequency of other non-vaccine types; presentation in other age groups). Based on nationwide registration, clinical information and laboratory findings were collected from all 65 confirmed cases of H. influenzae meningitis during the period 1994-2005. Twenty-nine patients (45%) were <13 years old [median 15 months (range 0-147)], and 36 patients (55%) were >24 years old [median 62 years (range 25-96)]. Hib accounted for 31% (20/65) of the cases, and significantly more children were infected with Hib compared with adults [53% (16/29) vs. 11% (4/36), respectively, p 0.0003]. Overall, 38% of cases had an otogenic focus and this was thus the most frequent primary focus of infection. Among children infected with Hib, two cases (13%) were identified as true vaccine failures. Six patients (9%) died; one premature infant infected with serotype f and five adults (age 83-96 years) with non-typeable H. influenzae. Hearing loss was reported in 16% of the surviving children and in 10% of the surviving adults. The presence of a lung focus was an independent prognostic factor for an unfavourable outcome (p 0.03). In conclusion, meningitis caused by Hib has been infrequent in Denmark after introduction of the Hib vaccine in the childhood vaccination programme, and no increase in meningitis cases due to non-b type H. influenzae has been observed. Cases with H. influenzae meningitis frequently had an otogenic focus, with low risk of an unfavourable outcome.

Invasive Haemophilus influenzae infections in Germany: impact of non-type b serotypes in the post-vaccine era

Background

Haemophilus influenzae type b (Hib) vaccination led to a significant decrease in invasive bacterial infections in children. The aim of this study was to assess a potential shift to more non-type b invasive infections in a population with high Hib vaccination coverage and to compare the burden of suffering between children with Hib, capsulated non-b and non-capsulated Hi infections.

Methods

Cases with confirmed invasive Hi infections were ascertained through two independent nationwide active surveillance systems in 1998–2005. Information on possible predisposing conditions and clinical information was available from 2001 onwards.

Results

The total number of reported non-type b Hi cases varied between 10 cases in 1998, 27 in 2000 and 14 in 2005. In each year, non-capsulated serotypes outnumbered capsulated non-type b ones. 192 cases were detected in 2001–2005, more than one half was non-type b and 88% of the non-type b cases were non-capsulated. For cases with Hib/capsulated non-type b infections the most common clinical presentation was meningitis (67% each); 89%/78% had no potential predisposing condition, 75%/72% completely recovered from disease and 6% (each) died. In contrast, meningitis was diagnosed in 34% of the non-capsulated Hi infections, septicaemia in 28% and pneumonia 21%; 62% had no potential predisposing condition, 83% completely recovered and 3% died.

Conclusion

There was no increase in non-type b Hi invasive infections during 8 years of active surveillance in Germany. Invasive disease due to non-type b Hi is not confined to children with risk factors. In patients with capsulated non-type b Hi infections the proportion of meningitis cases is similar to Hib, but double as high as in non-capsulated Hi.

Nontypeable Haemophilus influenzae as a pathogen in children

Nontypeable Haemophilus influenzae is a significant pathogen in children, causing otitis media, sinusitis, conjunctivitis, pneumonia, and occasionally invasive infections. H. influenzae type b conjugate vaccines have no effect on infections caused by nontypeable strains because nontypeable strains are nonencapsulated. Approximately, one-third of episodes of otitis media are caused by nontypeable H. influenzae and the bacterium is the most common cause of recurrent otitis media. Recent progress in elucidating molecular mechanisms of pathogenesis, understanding the role of biofilms in otitis media and an increasing understanding of immune responses have potential for development of novel strategies to improve prevention and treatment of otitis media caused by nontypeable H. influenzae. Feasibility of vaccination for prevention of otitis media due to nontypeable H. influenzae was recently demonstrated in a clinical trial with a vaccine that included the surface virulence factor, protein D.