PCR-based capsular serotype determination of Haemophilus influenzae strains recovered from Japanese paediatric patients with invasive infection

A nationwide population-based surveillance of invasive Haemophilus influenzae diseases in children after the introduction of the Haemophilus influenzae type b vaccine in Japan

BACKGROUND

Haemophilus influenzae type b (Hib) vaccine was introduced as a voluntary vaccine in December 2008 and was included in the national routine immunization program in April 2013 in Japan. Currently, no nationwide data are available to evaluate the effectiveness of Hib vaccine in Japan.

METHODS

To evaluate the effectiveness of Hib vaccine in Japan, nationwide active population-based surveillance of culture-proven invasive infections caused by H. influenzae in children was performed in 2008-2017 in 10 prefectures in Japan (covering approximately 23% of the total Japanese population). Clinical data were recorded on a standardized case report form. Capsular type and antimicrobial susceptibility of the H. influenzae isolates were examined. The incidence rate ratio (IRR) and its confidence interval (CI) were calculated to compare data from 5 years before and that from after the introduction of the national routine Hib vaccine immunization program.

RESULTS

During the 10-year study period, 566 invasive H. influenzae disease cases including 336 meningitis cases were identified. The average number of invasive H. influenzae disease cases among children <5 years of age during 2013-2017 decreased by 93% (IRR: 0.07, 95%CI 0.05-0.10, p < 0.001) compared with those occurring during 2008-2012. Hib strains have not been isolated from invasive H. influenzae disease cases since 2014; however, non-typeable H. influenzae and H. influenzae type f isolates have been noted as causes of invasive H. influenzae diseases among children <5 years in the post-Hib vaccine era.

CONCLUSIONS

After the governmental subsidization of the Hib vaccine, invasive Hib disease cases decreased dramatically in the study population, as per our surveillance. Continuous surveillance is necessary to monitor the effectiveness of Hib vaccine and for detecting any emerging invasive capsular types.

Capsular serotyping of Haemophilus influenzae by using matrix-associated laser desorption ionization-time of flight mass spectrometry

Haemophilus influenzae is a major pathogenic bacteria causing invasive disease, which is classified into six capsular serotypes (a-f) and non-typeable (NT) strains. Capsular serotyping of H. influenzae is traditionally determined by serological methods and more recently by PCR methods. However, these methods are time-consuming and expensive. In the present study, matrix-associated laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was evaluated as an alternative method for capsular serotyping of H. influenzae clinical strains. We created an in-house database of all six serotypes and NT H. influenzae strains using the main spectrum creation standard method set to the default parameters in MADI-TOF MS. We evaluated the performance of the in-house database using 79 clinical strains already identified by PCR and 58 prospectively collected clinical strains. Measurements were performed using the Bruker MALDI BioTyper system. The peak list was matched against the reference library using the integrated pattern algorithm of the software. The best-matched spectrum was considered the serotyping result. All 137 test strains were correctly identified as H. influenzae using MALDI-TOF MS. The sensitivity and specificity for identification for type b, type e, and type f capsular serotypes and NT H. influenzae using MALDI-TOF MS were 100%/94.3%, 94.7%/97.9%, 97.4%/97.9%, and 85.5%/99.2%, respectively. Our findings indicate that MALDI-TOF MS is a useful alternative method for capsular serotyping of H. influenzae strains. This method is faster and more cost-effective than traditional methods and will therefore be useful for routine applications in clinical laboratories.

Cost-effectiveness of Haemophilus influenzae type b conjugate vaccine in low- and middle-income countries: regional analysis and assessment of major determinants

OBJECTIVES

To estimate the cost-effectiveness of Haemophilus influenzae type b (Hib) conjugate vaccine in low- and middle-income countries and identify the model variables, which are most important for the result.

STUDY DESIGN

A static decision tree model was developed to predict incremental costs and health impacts. Estimates were generated for 4 country groups: countries eligible for funding by the GAVI Alliance in Africa and Asia, lower middle-income countries, and upper middle-income countries. Values, including disease incidence, case fatality rates, and treatment costs, were based on international country estimates and the scientific literature.

RESULTS

From the societal perspective, it is estimated that the probability of Hib conjugate vaccine cost saving is 34%-53% in Global Alliance for Vaccines and Immunization eligible African and Asian countries, respectively. In middle-income countries, costs per discounted disability adjusted life year averted are between US$37 and US$733. Variation in vaccine prices and risks of meningitis sequelae and mortality explain most of the difference in results. For all country groups, disease incidence cause the largest part of the uncertainty in the result.

CONCLUSIONS

Hib conjugate vaccine is cost saving or highly cost-effective in low- and middle-income settings. This conclusion is especially influenced by the recent decline in Hib conjugate vaccine prices and new data revealing the high costs of lost productivity associated with meningitis sequelae.

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.

[Susceptibility testing for Haemophilus influenzae isolated from pediatric cases during 2004-2008]

We tested for antimicrobial susceptibility of 1,317 clinical isolates of Haemophilus influenzae at a pediatric facility during 2004-2008. The percentage distribution of beta-lactamase-non-producing ampicillin (ABPC)-sensitive strain (BLNAS) was 47.8%, that of beta-lactamase-non-producing ABPC-resistant strain (BLNAR) 32.7% that of intermediately resistant strain (BLNAI) 8.9% that of beta-lactamase producing ABPC resistant strain (BLPAR) 6.8% and that of clavulanic acid/amoxicillin resistant strain (BLPACR) 3.7%. BLNAR prevalence was 30% between 2005 and 2008, increasing slowly. Though reduced susceptibility was seen in most beta-lactams, piperacillin and tazobactam/piperacillin showed good susceptibility for H. influenzae. Of 1,317 strains, 83 (6.3%) were serotype b (Hib). The frequency of Hib was high in sterilized site.

Rapid identification of nontypeable and serotype b Haemophilus influenzae from nasopharyngeal secretions by the multiplex PCR

OBJECTIVE

Heamophilus influenzae (H. influenzae) is an important pathogen responsible for both invasive and non-invasive infectious diseases. While encapsulated type b strain recognized as a major cause of severe invasive diseases, nontypeable strains are the major causes of non-invasive infectious diseases. Detection of this pathogen from nasopharyngeal secretions (NPS) is important.

METHODS

We developed a multiplex polymerase chain reaction (PCR) for rapid identification of nontypeable and serotype b H. influenzae from nasopharyngeal secretions.

RESULTS

A total 25 nasopharyngeal secretions were evaluated in this study. The multiplex PCR provided rapid and unequivocal results for determining either nontypeable or encapsulated typeable especially type b strains including a determination of beta-lactamase productions.

CONCLUSION

The multiplex PCR based serotyping provided more reliable results than slide agglutination test (SAT) and is a valuable and expeditious method for identification of H. influenzae with determining capsular serotypes.

Invasive Haemophilus influenzae infections in children in Kamikawa subprefecture, Hokkaido, Japan, 1996-2005, before the introduction of H. influenzae type b vaccination

We evaluated 52 children with invasive Haemophilus influenzae infection in Kamikawa subprefucture, Hokkaido, Japan between 1996 and 2005. The most frequent disease was meningitis, in 30 children (57.7%), followed by pneumonia in 9 (17.3%), bacteremia in 8 (15.4%), epiglottitis in 4 (7.7%), and cellulitis in 1 (1.9%). Patients ranged in age from 0 days to 8 years. Thirty (57.7%) of the patients were less than 2 years old. Only 6 cases of invasive H. influenzae infection occurred in children older than 5 years. Between 1996 and 2005 the annual incidence rates of invasive H. influenzae infection in children aged less than 5 years, and those aged from 5 to 9 years were 4.3/100,000 to 56.8/100,000 and 0/100,000 to 12.4/100,000, respectively. A marked increase of the annual incidence rate in children aged under 5 years was observed in the most recent 2 years (2004 and 2005). No patients with invasive H. influenzae infection died, but sequelae were seen at discharge in 2 patients with meningitis, predominantly epilepsy and developmental delay of varying severity. Two patients with epiglottitis were treated by endotracheal intubation or tracheostomy. Of 41 strains isolated from 1999 to 2005, 35 were classified for antimicrobial resistance by the polymerase chain reaction (PCR) method. The number of strains of beta-lactamase-negative ampicillin-susceptible, low beta-lactamase-negative ampicillin-resistant, beta-lactamase-negative ampicillin-resistant, beta-lactamase-negative amoxicillin/clavulanic acid resistant-I, and beta-lactamase-positive amoxicillin/clavulanic acid resistant-II, were 22, 3, 5, 2, and 3, respectively. The serotype in 37 (97.4%) of 38 cases demonstrated type b.

Peptides selected for binding to a virulent strain of Haemophilus influenzae by phage display are bactericidal

Nontypeable Haemophilus influenzae (NTHi) is an obligate parasite of the oropharynx of humans, in whom it commonly causes mucosal infections such as otitis media, sinusitis, and bronchitis. We used a subtractive phage display approach to affinity select for peptides binding to the cell surface of a novel invasive NTHi strain R2866 (also called Int1). Over half of the selected phage peptides tested were bactericidal toward R2866 in a dose-dependent manner. Five of the clones encoded the same peptide sequence (KQRTSIRATEGCLPS; clone hi3/17), while the remaining four clones encoded unique peptides. All of the bactericidal phage peptides but one were cationic and had similar physical-chemical properties. Clone hi3/17 possessed a similar level of activity toward a panel of clinical NTHi isolates and H. influenzae type b strains but lacked bactericidal activity toward gram-positive (Enterococcus faecalis, Staphylococcus aureus) and gram-negative (Proteus mirabilis, Pseudomonas aeruginosa, and Salmonella enterica) bacteria. These data indicate that peptides binding to bacterial surface structures isolated by phage display may prove of value in developing new antibiotics.