Epidemiologic study of Haemophilus influenzae causing invasive and non-invasive disease in Paraguay (1999-2017)

Trends in serotype distribution and antimicrobial susceptibility pattern of invasive Haemophilus influenzae isolates from Brazil, 2009-2021

INTRODUCTION

Invasive Haemophilus influenzae (Hi) disease poses a significant global health challenge. With the relaxation of COVID-19 pandemic measures and declining H. influenzae serotype b (Hib) vaccination coverage, there is concern about a potential increase in Hi cases worldwide.

METHODOLOGY

This study analyzed 1437 invasive Hi isolates in Brazil over 13 years, determining capsular serotypes, antimicrobial susceptibility, and genetic relatedness through multilocus sequence typing.

RESULTS

The primary source of isolation for these invasive H. influenzae isolates was blood (54.4%), followed by cerebrospinal fluid (37.1%) and lung specimens (8.5%), respectively. Consequently, bacteremia (47%) was the most common clinical presentation, followed by meningitis (39.6%) and pneumonia (13.4%). Non-encapsulated Hi (NTHi) predominated among the isolates (51.4%), along with serotype a (22%) and serotype b (21.5%) among the encapsulated isolates. The majority of the encapsulated isolates were isolated from children under 14 years of age (76.7%), while NTHi isolates were identified in patients older than 15 years, particularly those ≥ 60 years old (40%). Ampicillin resistance was observed in 17.1% of cases, displaying β-lactamase production as the principal resistance mechanism. MLST revealed a diverse NTHi population, whereas the encapsulated isolates presented a clonal structure.

CONCLUSION

This study describes the prevalence of NTHi isolates circulating in Brazil after two decades of the Hib vaccine immunization program. Continuous universal surveillance is crucial for implementing prompt public health measures to prevent and control invasive Hi disease and monitor changes in antibiotic resistance profiles.

Sentinel surveillance in bacterial pneumonia in children under 5 years old in a fourth-level pediatric hospital in Colombia 2016-2022

Objectives

Sentinel surveillance for bacterial pneumonia (SSBP) allows the monitoring of immunopreventable diseases. The results of the SSBP carried out at HOMI, Fundación Hospital pediátrico de la Misericordia, are presented.

Methods

The daily active search for cases was carried out in accordance with the protocol of the Pan American Health Organization from January 2016 to December 2022.

Results

There were 6970 suspected cases of bacterial pneumonia (BP). Among the 3048 (43.7%) patients with probable BP, cultures were obtained from 2777 (91.1%), and BP was confirmed in 190 (6.2%). The causes were Streptococcus pneumoniae in 98 (51.6%) cases, Spn19A in 47 (48%), Spn3 in 16 (16%), and Spn6C in 4 (4%). Haemophilus influenzae was found in 32 (16.8%) cases: non-typeable H. influenzae in 20 (62.5%), H. influenzae type b in five (15.6%), and H. influenzae type a in two (6.2%). Other bacteria were found in 60 (31.6%) cases. A total of 51.6% and 42.9% of patients with S. pneumoniae had decreased sensitivity to penicillin and ceftriaxone, respectively.

Conclusions

The serotypes included in the conjugate vaccines for pneumococcus and H. influenzae b decreased significantly, and serotype turnover was observed. Among the S. pneumoniae cases, Spn19A, Spn3, and Spn6C were the most frequent serotypes and associated with multiresistance. The SSBP allows us to determine the clinical behavior of the disease and to detect the serotypes emergence.

High Prevalence of Group III-Like Mutations Among BLPACR and First Report of Haemophilus influenzae ST95 Isolated from Blood in China

Purpose

We aimed to evaluate antibiotic resistance and molecular epidemiological characteristics of non-invasive Haemophilus influenzae (H. influenzae) from pneumonia patients and analyze the whole genome of one invasive H. influenzae isolated from blood in pediatric patients.

Methods

Antibiotic susceptibility was tested using the turbidimetric method. β-lactamase-producing and serotyping genes were evaluated via multiplex polymerase chain reaction (PCR), and ftsI was amplified using high-fidelity PCR. Lastly, whole genome sequencing (WGS) was conducted using Illumina HiSeq and PacBio sequencing technology.

Results

We observed that the ampicillin (AMP) and amoxicillin/clavulanate (AMC) resistance rates of non-invasive H. influenzae were as high as 99.06% (after adjustment) and 49.53%, respectively. The β-lactamase gene of 106 AMP-resistant strains was bla_TEM-1 . Group III-like mutation accounted for 71.15% of β-lactamase-positive, AMC-resistant (BLPACR) strain mutants. The novel Asn-526→His mutation was present in one β-lactamase-negative AMP-susceptible (BLNAS) strain. Non-invasive H. influenzae strains all belonged to non-typeable H. influenzae (NTHi). In contrast, the invasive H. influenzae 108 isolated from blood in China belonged to H. influenzae type b (Hib). It belonged to sequence typing ST95 and exhibited sensitivity to all 11 antibiotics. Three prophages were identified, and the capb loci of the H. influenzae strain 108 revealed regions I-III exist in duplicate; however, complete deletion of IS1016 was only present in one of the copies.

Conclusion

Non-invasive H. influenzae NTHi with β-lactamase-positive was highly prevalent. Notably, group III-like mutations had increased prevalence among BLPACR strains. H. influenzae belonging to Hib and ST95 was first reported to cause sepsis in China.

Laboratory surveillance of invasive Haemophilus influenzae disease in Argentina, 2011-2019

The incorporation of Haemophilus influenzae type b (Hib) vaccine into the Argentine National Immunization Program in 1998 resulted in a dramatic decrease in the incidence of invasive disease due to this serotype. We assessed 1405 H. influenzae (Hi) isolates causing invasive infections referred to the National Reference Laboratory between 2011 and 2019. Non-encapsulated Hi were the most common strains (44.5%), followed by types b (41.1%) and a (10.0%). Significant increase in the proportion of type b was observed, from 31.2% in 2011, to 50% in 2015, correlating with the peak incidence rate, later decreasing to 33.6% by 2019. We compared the genetic relationship between clones circulating during the period of increased Hib incidence (2011-2015) and those of the prevaccination-transition period (1997-1998). Four pulsotypes predominated in both periods, G, M, P and K, G being the most common. Multi-locus sequence typing revealed that the 4 pulsotypes belonged to ST6, or one of its simple or double locus variants. Isolates from fully vaccinated individuals did not differ from those of the rest of the population studied. After ruling out aspects associated with emergence of specific clones, we concluded that factors such as low booster coverage rates, delayed vaccination schedules and use of different vaccines may have contributed to the reemergence of Hib infections.

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.