Michael E. Pichichero

Background: Otitis media is highly prevalent during early life, yet the molecular factors that predispose children to recurrent episodes are poorly defined. Metabolomics captures dynamic biochemical changes and may help identify pathways influencing otitis susceptibility. We examined whether longitudinal infant plasma metabolomic profiles were associated with development of stringently‐defined otitis proneness in the Rochester Combined Cohort (RCC; Rochester, NY). Methods: Global plasma metabolomic profiling was performed in RCC samples collected between ~6 and 18 months of age using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Children were classified as stringently‐defined otitis prone (sOP) if they experienced ≥3 acute otitis media (AOM) episodes within a 6‐month period or ≥4 AOM episodes within a 12‐month period during the first 3 years of life; all AOM episodes were tympanocentesis‐confirmed. Generalized additive mixed models (GAMMs) assessed age‐dependent differences in plasma metabolite levels between sOP and non‐otitis‐prone (nOP) children, adjusting for potential confounders. Results: Several metabolites demonstrated age‐related declines in lipid and amino acid pathways, with consistently lower metabolite trajectories in the sOP group. Compared with nOP children, sOP children exhibited significantly lower levels of 16 metabolites related to inflammatory lipid signaling, redox metabolism, and fatty acid metabolism ( p < 4.4 × 10 ⁻⁴ ) and higher levels of glycerophosphoinositol ( p = 2.9 × 10 ⁻⁴ ). These findings were directionally consistent in a sensitivity analysis additionally adjusted for recent antibiotic use. Conclusion: Children who subsequently met sOP criteria by age 3 years exhibited distinct plasma metabolomic signatures during infancy, suggesting altered immune–metabolic programming preceding recurrent otitis media. Longitudinal metabolomics provides a promising framework to identify biochemical mechanisms underlying otitis proneness.

Nontypeable Haemophilus influenzae ( NTHi ) is a primary cause of acute otitis media (AOM) in children and lower respiratory tract infections in adults. Vaccines that can reduce nasopharyngeal carriage and prevent disease are needed. We used an adult murine model of nasopharyngeal carriage and AOM infection to evaluate immunogenicity and protection provided by subcutaneous and intramuscular vaccination with lipidated Protein D (L-PD) compared with non-lipidated PD (NL-PD) formulated with and without alum adjuvant. ELISA was used for antibody measurements and flow cytometry to characterize T-cell immunity. L-PD + Alum subcutaneous vaccination induced low levels of PD-specific IgG antibodies and significantly elevated Th17 and T effector memory cell activation in cervical lymph nodes and splenocytes compared with NL-PD + Alum. The addition of alum increased bactericidal antibody activity. Intramuscular vaccination with L-PD with and without alum induced 3- to 4-fold log ₁₀ higher PD-specific IgG antibodies than subcutaneous vaccination but did not elicit Th17 or T effector memory cell activation. Subcutaneous vaccination with L-PD + Alum protected mice within both the nasopharynx and middle ear. Middle ear bacterial density reduction correlated with IgG antibody levels after intramuscular vaccination with L-PD + Alum but not L-PD without alum, yet no protection from nasopharyngeal carriage occurred. PD + Alum vaccination increased humoral and cellular immunity and protected mice from NTHi carriage and AOM, whereas NL-PD did not. Activation of Th17 immunity by lipidation of PD and subcutaneous vaccination correlated with protection from nasopharyngeal carriage of NTHi .

Background: The estimated global incidence of acute otitis media (AOM) is >700 million episodes per year, with direct costs of billions of United States Dollars. This economic burden warrants continued investment in vaccine development against otopathogens. To aid in these decisions, an updated estimate of the incidence and costs of AOM and common sequelae is provided. Methods: A structured search using PubMed and Google Scholar that included English-language articles published from January 2000 to April 2024 was conducted using keywords and Boolean operators. Costs were adjusted to 2025 United States Dollars using the consumer price index inflation calculator provided by the US Bureau of Labor Statistics. Results: The US incidence of AOM is reported as 2- to 4-fold higher than most other high-income countries, and 3- to 6-fold higher than low- and middle-income countries (LMICs). However, studies of the point prevalence of AOM sequelae, such as chronic suppurative otitis media and acquired hearing loss, are higher in LMICs. The direct cost per AOM episode in the United States ranges from $397 to $718, for other high-income countries from $224 to $878 and for LMICs from $31 to $227. When indirect costs are incorporated, the economic burden of AOM in children under 5 years is estimated at $51–$68 billion/year. Conclusions: The worldwide incidence of AOM may be higher than prior estimates suggest. The reported frequency of AOM complications in LMICs, especially chronic suppurative otitis media and acquired deafness, is inconsistent with the reported low incidence rates. Costs per episode vary widely but represent a much larger economic burden than previously reported, supporting investment to prevent this infectious disease.

Haemophilus influenzae, a Gram-negative bacterium that is an obligate commensal of the human nasopharynx, is associated with both acute and chronic infections of the ears, adenoids, sinuses, and lungs, as well as pelvic inflammatory disease, sepsis, and meningitis. This diverse array of clinical disease phenotypes is due to H. influenzae’s natural competence providing for frequent distributed gene exchange among strains during polyclonal colonizations. We performed whole genome sequencing (WGS) on ∼1000 H. influenzae strains and combined these data with ∼600 publicly available genomes. Clinical metadata including isolation site and disease were available for all strains. Our goal was to identify variations in protein sequences inferred from the WGS that correlate with the clinical metadata. We employed the alpha-fold unsupervised machine-learning model to all protein sequences. For each unique AA sequence, a numerical vector was generated reflecting the protein’s biochemical properties. Multidimensional clustering was used to group variants into clusters by distance. For gene groups with two or more clusters, clinical metadata from the strain of origin was overlayed and subsequently tested for correlation with the clustering. This allowed identification of multiple gene groups with clusters of variants that correlated significantly with the patients’ disease. COG category analysis showed that many of the significant gene groups were associated with antibiotic targets. The TbpA gene group type was found to be significantly correlated with disease type with three of five variant clusters having a 95% prevalence among strains that were isolated from the lungs of COPD patients or other lower pulmonary tract infections.

Background: We analyzed the demographic and risk factors, middle ear fluid (MEF) pathogens, pneumococcus serotype distribution, and bacterial antibiotic nonsusceptibility among children with uncomplicated acute otitis media (uAOM) and complex acute otitis media (cAOM) over 3 timeframes: 2006–2009 (7-valent pneumococcal conjugate vaccine [PCV7] era), 2010–2014 (early 13-valent pneumococcal conjugate vaccine [PCV13] era), and 2015–2023 (late PCV13 era). Methods: A total of 1537 children were enrolled over 18 years and prospectively followed from 6 to 36 months of age. Upon diagnosis of AOM, tympanocentesis was performed for MEF collection and culture. Electronic medical records were analyzed to identify uAOM and cAOM episodes. Results: Analysis of demographic data showed that male sex, family history of AOM, and daycare attendance increased the odds of developing cAOM compared to uAOM. Streptococcus pneumoniae was less likely in cAOM, and Haemophilus influenzae more likely as compared to uAOM. AOM caused by S pneumoniae decreased significantly in the early and late PCV13 eras. This was driven by decreases in cAOM caused by PCV13 S pneumoniae strains, especially serotype 19A. Streptococcus pneumoniae penicillin nonsusceptibility was associated with cAOM and declined in the early PCV13 era. Conclusions: The risk factors for developing cAOM compared to uAOM are similar. PCV13 significantly reduced cAOM and penicillin nonsusceptibility associated with S pneumoniae, driven by reduction in cases caused by serotype 19A. Haemophilus influenzae continued to be a dominant cause of cAOM. Although non-PCV13 S pneumoniae serotypes emerged in the late PCV13 era, the lower level of cAOM caused by S pneumoniae was sustained.

Introduction: We sought to explore the variability of antibody responses to multiple vaccines during early life in individual children, assess the trajectory of each child longitudinally, determine the associations of demographic variables and antibiotic exposures with vaccine-induced immunity, and link vaccine responsiveness to infection proneness. Methods: In 357 prospectively-recruited children, age six through 36 months, antibody levels to 13 routine vaccine antigens were measured in sera at multiple time points and normalized to their respective protective thresholds to categorize children into four groups: very low, low, normal, and high vaccine responder. Demographic variables and frequency of antibiotic exposure data were collected. Participants were followed to determine change in vaccine groups over time and occurrences of infections. Results: Vaccine-induced antibody levels persisted over time as very low, low, normal, or high in individual children and changed post-primary through post-booster immunizations against multiple antigen types, including toxoids, purified proteins, polysaccharide-protein conjugates, recombinant proteins and inactivated viruses. Factors influencing persistence or change in vaccine response group were assessed. Children who did not attend day care and African American/multiracial children had higher vaccine-induced antibody levels than White children. Children with lower vaccine-induced antibody levels had more frequent antibiotic exposures. Low vaccine responsiveness was linked to more frequent antibiotic-treated bacterial infections. Conclusion: When vaccine-induced antibody levels are used to define vaccine response groups, individual children may persist or change groups over time, which is associated with demographic variables and influenced by antibiotic exposures. Lower vaccine responsiveness can be linked to more frequent antibiotic-treated bacterial infections.

We hypothesized that the introduction of 13-valent pneumococcal conjugate vaccine (PCV13) would alter patterns of nasopharyngeal colonization and their relationship to acute otitis media (AOM) in children. We prospectively followed 1537 children from age 6–36 months across three periods: 2006–2009 (PCV7 era), 2010–2014 (early-PCV13 era), and 2015–2023 (late-PCV13 era), collecting nasopharyngeal cultures at healthy and AOM visits, with paired tympanocentesis when appropriate. Colonized children had more frequent daycare attendance and less breastfeeding. Children with no AOM differed from those with uncomplicated AOM (uAOM) by less colonization with respiratory pathogens. Complex AOM (cAOM) nasopharyngeal samples exhibited a higher frequency of Haemophilus influenzae, and vaccine serotype Streptococcus pneumoniae, compared to no AOM and uAOM children. Serotype distribution of S. pneumoniae changed, with replacement of PCV13 serotypes. Streptococcus pneumoniae nasopharyngeal isolation rates remained stable despite serotype replacement. Haemophilus influenzae isolation rates remained constant and Moraxella catarrhalis increased. Nasopharyngeal culture was a poor predictor of middle ear fluid culture. Respiratory bacterial pathogen distribution in healthy children and those with uAOM were similar and both were distinct from cAOM, with significant vaccine-driven serotype replacement occurring without reducing overall pneumococcal colonization.