Analysis of Haemophilus influenzae serotype f isolated from three Japanese children with invasive H. influenzae infection

Haemophilus influenzae type f in the post-Haemophilus influenzae type b vaccination era: a systematic review

Since the introduction of Haemophilus influenzae (Hi) serotype b (Hib) vaccination, reports of increasing incidence rates of non-Hib serotypes have emerged. A systematic review was performed to investigate whether the Hi serotype f (Hif) incidence rate has increased globally and to describe its associated disease burden. In the post-Hib vaccine era, evidence shows that the incidence rate of Hif infection is increasing worldwide. In total 94 studies including 2 701 patients reported Hif infections. The estimated pooled incidence rate of Hif infection was 0.15/100 000 population per year (range: 0.05–0.40/100 000), with a median case fatality ratio of 14.3 %. Invasive infections most frequently presented as pneumonia (45 %), septicaemia (34 %) and meningitis (20 %). Of 191 Hif isolates, 87 % were ampicillin-susceptible. Multi-locus sequence typing revealed that Hif were relatively clonal, with the majority belonging to clonal complex 124. Hif causes invasive infections of significant variance in both severity and presentation. Globally, the Hif population shows little genetic variability and currently appears to possess low resistance to antimicrobials.

Haemophilus influenzaenon-type b Invasive Disease in Children ≤ 5 yearsof age: A Case Report and Review of Literature.. [DOI: 10.14293/s2199-1006.1.sor-.ppwt6cv.v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background:

Haemophilus influenzae type b (Hib) was the leading cause of invasive disease in children <5 years of age before the introduction of Hib conjugate vaccines. Invasive disease due to non-type H. influenzae has been increasingly reported.

Aims:

To describe a case of invasive non-type b Haemophilus influenzae and review the literature.

Case and Methods:

We describe a case of a 4-month-old male presented with fever and lethargy, subsequently diagnosed with bacteremia and meningitis due to Haemophilus influenzae type a (Hia). His clinical course was complicated by subdural empyema (figure 1) and seizures with complete recovery following surgical drainage and prolonged antibiotic therapy. We searched PubMed and Embase from 2010 to 2020 for case reports of non-type b Hi invasive disease in children ≤ 5 years.

Results:

Out of 138 articles screened, 17 were selected for review. 31 individual cases were summarized with 25% reported in the US. Calculated mean age was 1.5 years (range 0-5 years). Most common presentation was bacteremia (80%, 25) and meningitis (55%, 17). Most cases caused by Hia (52%, 16). About 29% (9) has underlying combordities, and additional 13% (4) were later diagnosed with immunodeficiency condition. Subdural collection and seizures occurred separately in 16% (5) Majority of patients recovered, and 3 (10%) died.

Conclusion:

Non-type b Hi invasive disease can lead to high morbidity and mortality in children. Epidemiologic surveillance and serotyping are crucial to monitor changing epidemiology of Hi invasive disease. Inclusion of non-type b strains in the Hib conjugate vaccine may be necessary to protect against H. influenzae invasive disease .

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

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

Identification of Haemophilus influenzae serotype e strains missing the fucK gene in clinical isolates from Japan

Introduction. Certain nontypeable Haemophilus influenzae cannot be assigned a sequence type (ST) by Multilocus Sequence Typing (MLST) due to the lack of the fucK gene, one of seven MLST loci in H. influenzae, which encodes a fucose-operon enzyme.Aims. To confirm whether the loss of fucK is also found in the encapsulated strains, we analysed clinical isolates of H. influenzae serotype e (Hie).Methodology. We conducted MLST, PFGE, and antimicrobial susceptibility tests of 45 Hie strains; the majority (n=43) were derived from respiratory samples of pediatric patients at Chiba Children's Hospital between 2000 and 2016. The two remaining strains were obtained from the blood of elderly patients with invasive H. influenzae diseases (IHiDs) between 2015 and 2016 at general hospitals. For the fucK-negative strains, PCR analysis for fucose operon was also performed.Results. Four STs (ST18, 122, 621 and 1758) were assigned to 13 strains, and remaining 32 (including one associated with IHiD) were fucK-negative, completely missing the fucose operon. The allelic profiles of six other loci were identical among 31 strains and to that of ST18, 122 and 621, and these strains were genetically closely related. Forty of 45 isolates were ampicillin-sensitive.Conclusions. The loss of fucK was frequently observed in clinical isolates of Hie from children. Moreover, fucK-negative Hie may be the cause of IHiD in adult patients. The majority of Hie, including fucK-negative strains, were shown to be clonally related and were ampicillin sensitive. This represents the first report examining fucK losses in encapsulated H. influenzae.

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

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

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.

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

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

Pediatric bacterial meningitis in Japan, 2013-2015 - 3-5 years after the wide use of Haemophilus influenzae type b and Streptococcus pneumoniae conjugated vaccines

BACKGROUND

Haemophilus influenzae type b (Hib) vaccine and pneumococcal conjugated vaccine (PCV) have been widely used since 2010 in Japan when both vaccines were supported by the regional governments, and they were covered as routine recommended vaccines in 2013. The incidence of bacterial meningitis due to these organisms decreased in 2011 and 2012, but meningitis due to Streptococcus agalactiae and Escherichia coli remained unchanged.

OBJECTIVES

We planned to confirm whether the incidence also decreased in subsequent years.

METHODS

We analyzed the epidemiological and clinical data for 2013-2015, and compared the information obtained in the previous nationwide survey database and our previous reports. We also investigated the risk factors for disease outcome.

RESULTS

In the 2013-2015 surveys, 407 patients from 366 hospitals from all prefectures were evaluated. S. agalactiae (33%), Streptococcus pneumoniae (25%), and E. coli (10%) were the main organisms. The total number of patients hospitalized with bacterial meningitis per 1000 admissions decreased from 1.19 in 2009-2010 to 0.37 in 2013-2015 (p < 0.001). The incidence of H. influenzae and S. pneumoniae meningitis significantly decreased from 0.66 in 2009-2010 to 0.01 in 2013-2015, and from 0.30 to 0.09, respectively (p < 0.001). Only 0-2 cases with Neisseria meningitidis were reported each year throughout 2001-2015. The fatality rates for H. influenzae, S. pneumoniae, S. agalactiae, and E. coli in 2013-2015 were 0.0, 4.1, 3.1, and 2.6%, respectively. Risk factors for death and sequelae were consciousness disturbance, convulsion, low CSF glucose, and Staphylococcus sp. as a causative organism (p < 0.01).

CONCLUSIONS

Hib vaccine and PCV have decreased the rate of bacterial meningitis. S. agalactiae has subsequently become the most common cause of bacterial meningitis in Japan.

Invasive Haemophilus influenzae Serotype f Case Reports in Mazovia Province, Poland

After successful introduction of anti-Haemophilus influenzae (Hi) serotype b vaccination program in Poland, invasive non-b or nontypeable H. influenzae infections have been reported more frequently alike in other countries all over the world. In this paper, we report 2 cases of H. influenzae serotype f (Hif) meningitis with severe clinical presentations which are rarely seen in previously healthy children.The first case is a 6-year-old girl who was admitted to pediatric ward with signs of meningitis. Laboratory tests confirmed bacteremic meningitis caused by Hif. The girl responded very well to administered treatment and recovered without any further complications. No underlying comorbidities were found. The second patient was a 4-year-old boy who, in course of Hif bacteremic meningitis, developed rapid septicemia and, despite aggressive treatment, died within a few hours of hospitalization. The child's past history was unremarkable.By presenting these cases, we would like to remind clinicians that invasive non-b Hi infections can become fatal not only in the group of the youngest children or children with coexisting comorbidities, as most commonly reported in the worldwide literature. At the same time, we want to emphasize the legitimacy of constant monitoring Hi epidemiology in order to take accurate actions if necessary.

Adult-onset Invasive Haemophilus influenzae Type f Caused by Acute Lower Leg Cellulitis

In Japan, routine Haemophilus influenzae type b (Hib) vaccination began in 2013. Thus, similar to other countries, a strain shift is expected in the near future. We experienced a case of H. influenzae type f (Hif) bacteremia in a 66-year-old man. The primary focus of the infection was the soft tissue of the left lower leg, which is an extremely rare origin in adults. Subsequently, we conducted multilocus sequence typing and identified the strain as sequence type 124, which is the most common invasive strain of Hif worldwide. This case may mark the beginning of an Hif strain shift in Japan.

Haemophilus influenzae Type f Hijacks Vitronectin Using Protein H To Resist Host Innate Immunity and Adhere to Pulmonary Epithelial Cells

The incidence of invasive Haemophilus influenzae type b (Hib) disease has significantly decreased since the introduction of an efficient vaccine against Hib. However, in contrast to Hib, infections caused by H. influenzae serotype f (Hif) are emerging. We recently did a whole genome sequencing of an invasive Hif isolate, and reported that Hif interacts with factor H by expressing protein H (PH). In this study, upon screening with various human complement regulators, we revealed that PH is also a receptor for vitronectin (Vn), an abundant plasma protein that regulates the terminal pathway of the human complement system in addition to being a component of the extracellular matrix. Bacterial Vn binding was significantly reduced when the lph gene encoding PH was deleted in an invasive Hif isolate. The dissociation constant (KD) of the interaction between recombinant PH and Vn was 2.2 μM, as revealed by Biolayer interferometry. We found that PH has different regions for simultaneous interaction with both Vn and factor H, and that it recognized the C-terminal part of Vn (aa 352-362). Importantly, PH-dependent Vn binding resulted in better survival of the wild-type Hif or PH-expressing Escherichia coli when exposed to human serum. Finally, we observed that PH mediated an increased bacterial adherence to alveolar epithelial cells in the presence of Vn. In conclusion, our study reveals that PH most likely plays an important role in Hif pathogenesis by increasing serum resistance and adhesion to the airways.