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New research was presented at the International Society for Otitis Media meeting in June 2019, which I attended. I would like to share a selection of new findings from the many presentations.
Transtympanic antibiotic delivery
Topical therapy has been used to treat only otitis externa and acute otitis media (AOM) with ear discharge. Giving antibiotics through the tympanic membrane could mitigate many of the concerns about antibiotic use driving antibiotic resistance of bacteria among children. Up to now, using antibiotics in the ear canal to treat AOM has not been considered because the tympanic membrane is highly impermeable to the transtympanic diffusion of any drugs. However, in recent years, a number of different drug delivery systems have been developed, and in some cases, animal studies have shown that noninvasive transtympanic delivery is possible so that drugs can reach high concentrations in the middle ear without damage. Nanovesicles and nanoliposomes that contain antibiotics and are small enough to pass through the eardrum have been developed and tested in animal models; these show promise. Ototopical administration of a drug called vinpocetine that was repurposed has been tested in mice and shown to reduce inflammation and mucus production in the middle ear during otitis media.
Biofilms
Antibiotic treatment failure can occur in AOM for several reasons. The treatment of choice, amoxicillin, for example may fail to achieve an adequate concentration because of poor absorption in the gastrointestinal tract or poor penetration into the middle ear. Or, the antibiotic chosen may not be effective because of resistance of the strain causing the infection. Another explanation, especially in recurrent AOM and chronic AOM, could be the presence of biofilms. Biofilms are multicellular bacterial communities incorporated in a polymeric, plasticlike matrix in which pathogens are protected from antibiotic activity. The biofilm provides a physical barrier to antibiotic penetration, and bacteria can persist in the middle ear and periodically cause a new AOM. If AOM persists or becomes a more chronic otitis media with effusion, the “glue ear” causes an environment in the middle ear that is low in oxygen. A low-oxygen environment is favorable to biofilms. Also one might expect that middle ear pus would have a low pH, but actual measurements show the pH is highly alkaline. Species of Haemophilus influenzae have been identified as more virulent when in an alkaline pH or the alkaline pH makes the H. influenzae persist better in the middle ear, perhaps in a biofilm. To eliminate biofilms and improve antibiotic efficacy, a vaccine against a protein expressed by H. influenzae has been developed. Antibodies against this protein have been shown to disrupt and prevent the formation of biofilms in an animal model.
Probiotics
The normal bacteria that live in the nasopharynx of children with recurrent AOM is now known to differ from that of children who experience infrequent AOM or remain AOM-free throughout childhood. The use of oral pre- and probiotics for AOM prophylaxis remains debated because the results of studies are conflicting and frequently show no effect. So the idea of using prebiotics or probiotics to create a favorable “microbiome” of the nose is under investigation. Two species of bacteria that are gathering the most attention are Corynebacterium species (a few types in particular) and a bacteria called Dolosigranulum pigrum. Delivery of the commensal species would be as a nose spray.
Vaccines
The use of pneumococcal conjugate vaccines (PCVs) has reduced the frequency of AOM caused by Streptococcus pneumoniae. PCVs are not as effective against AOM as they are against invasive pneumococcal disease, but they still help a lot. However, because there are now at least 96 different serotypes of the pneumococcus based on different capsular types, we see a pattern of replacement of disease-causing strains by new strains within a few years of introduction of a new formulation. We started with 7 serotypes (Prevnar 7) in year 2000, and it was replaced by the current formulation with 13 serotypes (Prevnar 13) in 2010. Replacements have occurred again so vaccine companies are making new formulations for the future that include more serotypes, up to 20 serotypes. But, technically and feasibility-wise there is a limit to making such vaccines. A vaccine based on killed unencapsulated bacteria has been tested for safety and immunogenicity in young children. There is no test so far for prevention of AOM. Another type of vaccine based on proteins expressed by the pneumococcus that could be vaccine targets was tested in American Navajo children, and it failed to be as efficacious as hoped.
Biomarkers.
Due to recurrent AOM or persistent otitis media with effusion, about 15% of children in the United States receive tympanostomy tubes. Among those who receive tubes, about 20% go on to receive a second set of tubes, often with adenotonsillectomy. To find a biomarker that could identify children likely to require a second set of tubes, the fluid in the middle ear was tested when a first set of tubes were inserted. If bacteria were detected by polymerase chain reaction (PCR) testing or if a profile of specific inflammatory cytokines was measured, those results could be used to predict a high likelihood for a second set of tubes.
Overdiagnosis
Diagnosis of AOM is challenging in young children, in whom it most frequently occurs. The ear canal is typically about 3 mm wide, the child struggles during the examination, and diagnostic skills are not taught in training, resulting in a high overdiagnosis rate. I presented data that suggest too many children who are not truly otitis prone have been classified as otitis prone based on incorrect clinical diagnosis. My colleagues and I found that 30% of children reach the threshold of three episodes of AOM in 6 months or four within a year when diagnosed by community pediatricians, similar to many other studies. Validated otoscopists (trained by experts with diagnosis definitively proven as at least 85% accurate using tympanocentesis) classify 15% of children as otitis prone – half as many. If tympanocentesis is used to prove middle ear fluid has bacterial pathogens (about 95% yield a bacterial otopathogen using culture and PCR), then about 10% of children are classified as otitis prone – one-third as many. This suggests that children clinically diagnosed by community-based pediatricians are overdiagnosed with AOM, perhaps three times more often than true. And that leads to overuse of antibiotics and referrals for tympanostomy tube surgery more often than should occur. So we need to improve diagnostic methods beyond otoscopy. New types of imaging for the eardrum and middle ear using novel technologies are in early clinical trials.
Immunity
The notion that young children get AOM because of Eustachian tube dysfunction in their early years of life (horizontal anatomy) may be true, but there is more to the story. After 10 years of work, the scientists in my research group have shown that children in the first 3 years of life can have an immune system that is suppressed – it is poorly responsive to pathogens and routine pediatric vaccines. Many features resemble a neonatal immune system, beginning life with a suppressed immune system or being in cytokine storm from birth. We introduced the term “prolonged neonatal-like immune profile (PNIP)” to give a general description of the immune responses we have found in otitis-prone children. They outgrow this. So the immune maturation is delayed but not permanent. It is mostly resolved by age 3 years. We found problems in both innate and adaptive immunity. It may be that the main explanation for recurrent AOM in the first years of life is PNIP. Scientists from Australia also reported immunity problems in Aboriginal children and they are very otitis prone, often progressing to chronic suppurative otitis media. Animal model studies of AOM show inadequate innate and adaptive immunity importantly contribute to the infection as well.
Dr. Pichichero is a specialist in pediatric infectious diseases and director of the Research Institute at Rochester (N.Y.) General Hospital. He has no conflicts to declare. Email him at [email protected].
New research was presented at the International Society for Otitis Media meeting in June 2019, which I attended. I would like to share a selection of new findings from the many presentations.
Transtympanic antibiotic delivery
Topical therapy has been used to treat only otitis externa and acute otitis media (AOM) with ear discharge. Giving antibiotics through the tympanic membrane could mitigate many of the concerns about antibiotic use driving antibiotic resistance of bacteria among children. Up to now, using antibiotics in the ear canal to treat AOM has not been considered because the tympanic membrane is highly impermeable to the transtympanic diffusion of any drugs. However, in recent years, a number of different drug delivery systems have been developed, and in some cases, animal studies have shown that noninvasive transtympanic delivery is possible so that drugs can reach high concentrations in the middle ear without damage. Nanovesicles and nanoliposomes that contain antibiotics and are small enough to pass through the eardrum have been developed and tested in animal models; these show promise. Ototopical administration of a drug called vinpocetine that was repurposed has been tested in mice and shown to reduce inflammation and mucus production in the middle ear during otitis media.
Biofilms
Antibiotic treatment failure can occur in AOM for several reasons. The treatment of choice, amoxicillin, for example may fail to achieve an adequate concentration because of poor absorption in the gastrointestinal tract or poor penetration into the middle ear. Or, the antibiotic chosen may not be effective because of resistance of the strain causing the infection. Another explanation, especially in recurrent AOM and chronic AOM, could be the presence of biofilms. Biofilms are multicellular bacterial communities incorporated in a polymeric, plasticlike matrix in which pathogens are protected from antibiotic activity. The biofilm provides a physical barrier to antibiotic penetration, and bacteria can persist in the middle ear and periodically cause a new AOM. If AOM persists or becomes a more chronic otitis media with effusion, the “glue ear” causes an environment in the middle ear that is low in oxygen. A low-oxygen environment is favorable to biofilms. Also one might expect that middle ear pus would have a low pH, but actual measurements show the pH is highly alkaline. Species of Haemophilus influenzae have been identified as more virulent when in an alkaline pH or the alkaline pH makes the H. influenzae persist better in the middle ear, perhaps in a biofilm. To eliminate biofilms and improve antibiotic efficacy, a vaccine against a protein expressed by H. influenzae has been developed. Antibodies against this protein have been shown to disrupt and prevent the formation of biofilms in an animal model.
Probiotics
The normal bacteria that live in the nasopharynx of children with recurrent AOM is now known to differ from that of children who experience infrequent AOM or remain AOM-free throughout childhood. The use of oral pre- and probiotics for AOM prophylaxis remains debated because the results of studies are conflicting and frequently show no effect. So the idea of using prebiotics or probiotics to create a favorable “microbiome” of the nose is under investigation. Two species of bacteria that are gathering the most attention are Corynebacterium species (a few types in particular) and a bacteria called Dolosigranulum pigrum. Delivery of the commensal species would be as a nose spray.
Vaccines
The use of pneumococcal conjugate vaccines (PCVs) has reduced the frequency of AOM caused by Streptococcus pneumoniae. PCVs are not as effective against AOM as they are against invasive pneumococcal disease, but they still help a lot. However, because there are now at least 96 different serotypes of the pneumococcus based on different capsular types, we see a pattern of replacement of disease-causing strains by new strains within a few years of introduction of a new formulation. We started with 7 serotypes (Prevnar 7) in year 2000, and it was replaced by the current formulation with 13 serotypes (Prevnar 13) in 2010. Replacements have occurred again so vaccine companies are making new formulations for the future that include more serotypes, up to 20 serotypes. But, technically and feasibility-wise there is a limit to making such vaccines. A vaccine based on killed unencapsulated bacteria has been tested for safety and immunogenicity in young children. There is no test so far for prevention of AOM. Another type of vaccine based on proteins expressed by the pneumococcus that could be vaccine targets was tested in American Navajo children, and it failed to be as efficacious as hoped.
Biomarkers.
Due to recurrent AOM or persistent otitis media with effusion, about 15% of children in the United States receive tympanostomy tubes. Among those who receive tubes, about 20% go on to receive a second set of tubes, often with adenotonsillectomy. To find a biomarker that could identify children likely to require a second set of tubes, the fluid in the middle ear was tested when a first set of tubes were inserted. If bacteria were detected by polymerase chain reaction (PCR) testing or if a profile of specific inflammatory cytokines was measured, those results could be used to predict a high likelihood for a second set of tubes.
Overdiagnosis
Diagnosis of AOM is challenging in young children, in whom it most frequently occurs. The ear canal is typically about 3 mm wide, the child struggles during the examination, and diagnostic skills are not taught in training, resulting in a high overdiagnosis rate. I presented data that suggest too many children who are not truly otitis prone have been classified as otitis prone based on incorrect clinical diagnosis. My colleagues and I found that 30% of children reach the threshold of three episodes of AOM in 6 months or four within a year when diagnosed by community pediatricians, similar to many other studies. Validated otoscopists (trained by experts with diagnosis definitively proven as at least 85% accurate using tympanocentesis) classify 15% of children as otitis prone – half as many. If tympanocentesis is used to prove middle ear fluid has bacterial pathogens (about 95% yield a bacterial otopathogen using culture and PCR), then about 10% of children are classified as otitis prone – one-third as many. This suggests that children clinically diagnosed by community-based pediatricians are overdiagnosed with AOM, perhaps three times more often than true. And that leads to overuse of antibiotics and referrals for tympanostomy tube surgery more often than should occur. So we need to improve diagnostic methods beyond otoscopy. New types of imaging for the eardrum and middle ear using novel technologies are in early clinical trials.
Immunity
The notion that young children get AOM because of Eustachian tube dysfunction in their early years of life (horizontal anatomy) may be true, but there is more to the story. After 10 years of work, the scientists in my research group have shown that children in the first 3 years of life can have an immune system that is suppressed – it is poorly responsive to pathogens and routine pediatric vaccines. Many features resemble a neonatal immune system, beginning life with a suppressed immune system or being in cytokine storm from birth. We introduced the term “prolonged neonatal-like immune profile (PNIP)” to give a general description of the immune responses we have found in otitis-prone children. They outgrow this. So the immune maturation is delayed but not permanent. It is mostly resolved by age 3 years. We found problems in both innate and adaptive immunity. It may be that the main explanation for recurrent AOM in the first years of life is PNIP. Scientists from Australia also reported immunity problems in Aboriginal children and they are very otitis prone, often progressing to chronic suppurative otitis media. Animal model studies of AOM show inadequate innate and adaptive immunity importantly contribute to the infection as well.
Dr. Pichichero is a specialist in pediatric infectious diseases and director of the Research Institute at Rochester (N.Y.) General Hospital. He has no conflicts to declare. Email him at [email protected].
New research was presented at the International Society for Otitis Media meeting in June 2019, which I attended. I would like to share a selection of new findings from the many presentations.
Transtympanic antibiotic delivery
Topical therapy has been used to treat only otitis externa and acute otitis media (AOM) with ear discharge. Giving antibiotics through the tympanic membrane could mitigate many of the concerns about antibiotic use driving antibiotic resistance of bacteria among children. Up to now, using antibiotics in the ear canal to treat AOM has not been considered because the tympanic membrane is highly impermeable to the transtympanic diffusion of any drugs. However, in recent years, a number of different drug delivery systems have been developed, and in some cases, animal studies have shown that noninvasive transtympanic delivery is possible so that drugs can reach high concentrations in the middle ear without damage. Nanovesicles and nanoliposomes that contain antibiotics and are small enough to pass through the eardrum have been developed and tested in animal models; these show promise. Ototopical administration of a drug called vinpocetine that was repurposed has been tested in mice and shown to reduce inflammation and mucus production in the middle ear during otitis media.
Biofilms
Antibiotic treatment failure can occur in AOM for several reasons. The treatment of choice, amoxicillin, for example may fail to achieve an adequate concentration because of poor absorption in the gastrointestinal tract or poor penetration into the middle ear. Or, the antibiotic chosen may not be effective because of resistance of the strain causing the infection. Another explanation, especially in recurrent AOM and chronic AOM, could be the presence of biofilms. Biofilms are multicellular bacterial communities incorporated in a polymeric, plasticlike matrix in which pathogens are protected from antibiotic activity. The biofilm provides a physical barrier to antibiotic penetration, and bacteria can persist in the middle ear and periodically cause a new AOM. If AOM persists or becomes a more chronic otitis media with effusion, the “glue ear” causes an environment in the middle ear that is low in oxygen. A low-oxygen environment is favorable to biofilms. Also one might expect that middle ear pus would have a low pH, but actual measurements show the pH is highly alkaline. Species of Haemophilus influenzae have been identified as more virulent when in an alkaline pH or the alkaline pH makes the H. influenzae persist better in the middle ear, perhaps in a biofilm. To eliminate biofilms and improve antibiotic efficacy, a vaccine against a protein expressed by H. influenzae has been developed. Antibodies against this protein have been shown to disrupt and prevent the formation of biofilms in an animal model.
Probiotics
The normal bacteria that live in the nasopharynx of children with recurrent AOM is now known to differ from that of children who experience infrequent AOM or remain AOM-free throughout childhood. The use of oral pre- and probiotics for AOM prophylaxis remains debated because the results of studies are conflicting and frequently show no effect. So the idea of using prebiotics or probiotics to create a favorable “microbiome” of the nose is under investigation. Two species of bacteria that are gathering the most attention are Corynebacterium species (a few types in particular) and a bacteria called Dolosigranulum pigrum. Delivery of the commensal species would be as a nose spray.
Vaccines
The use of pneumococcal conjugate vaccines (PCVs) has reduced the frequency of AOM caused by Streptococcus pneumoniae. PCVs are not as effective against AOM as they are against invasive pneumococcal disease, but they still help a lot. However, because there are now at least 96 different serotypes of the pneumococcus based on different capsular types, we see a pattern of replacement of disease-causing strains by new strains within a few years of introduction of a new formulation. We started with 7 serotypes (Prevnar 7) in year 2000, and it was replaced by the current formulation with 13 serotypes (Prevnar 13) in 2010. Replacements have occurred again so vaccine companies are making new formulations for the future that include more serotypes, up to 20 serotypes. But, technically and feasibility-wise there is a limit to making such vaccines. A vaccine based on killed unencapsulated bacteria has been tested for safety and immunogenicity in young children. There is no test so far for prevention of AOM. Another type of vaccine based on proteins expressed by the pneumococcus that could be vaccine targets was tested in American Navajo children, and it failed to be as efficacious as hoped.
Biomarkers.
Due to recurrent AOM or persistent otitis media with effusion, about 15% of children in the United States receive tympanostomy tubes. Among those who receive tubes, about 20% go on to receive a second set of tubes, often with adenotonsillectomy. To find a biomarker that could identify children likely to require a second set of tubes, the fluid in the middle ear was tested when a first set of tubes were inserted. If bacteria were detected by polymerase chain reaction (PCR) testing or if a profile of specific inflammatory cytokines was measured, those results could be used to predict a high likelihood for a second set of tubes.
Overdiagnosis
Diagnosis of AOM is challenging in young children, in whom it most frequently occurs. The ear canal is typically about 3 mm wide, the child struggles during the examination, and diagnostic skills are not taught in training, resulting in a high overdiagnosis rate. I presented data that suggest too many children who are not truly otitis prone have been classified as otitis prone based on incorrect clinical diagnosis. My colleagues and I found that 30% of children reach the threshold of three episodes of AOM in 6 months or four within a year when diagnosed by community pediatricians, similar to many other studies. Validated otoscopists (trained by experts with diagnosis definitively proven as at least 85% accurate using tympanocentesis) classify 15% of children as otitis prone – half as many. If tympanocentesis is used to prove middle ear fluid has bacterial pathogens (about 95% yield a bacterial otopathogen using culture and PCR), then about 10% of children are classified as otitis prone – one-third as many. This suggests that children clinically diagnosed by community-based pediatricians are overdiagnosed with AOM, perhaps three times more often than true. And that leads to overuse of antibiotics and referrals for tympanostomy tube surgery more often than should occur. So we need to improve diagnostic methods beyond otoscopy. New types of imaging for the eardrum and middle ear using novel technologies are in early clinical trials.
Immunity
The notion that young children get AOM because of Eustachian tube dysfunction in their early years of life (horizontal anatomy) may be true, but there is more to the story. After 10 years of work, the scientists in my research group have shown that children in the first 3 years of life can have an immune system that is suppressed – it is poorly responsive to pathogens and routine pediatric vaccines. Many features resemble a neonatal immune system, beginning life with a suppressed immune system or being in cytokine storm from birth. We introduced the term “prolonged neonatal-like immune profile (PNIP)” to give a general description of the immune responses we have found in otitis-prone children. They outgrow this. So the immune maturation is delayed but not permanent. It is mostly resolved by age 3 years. We found problems in both innate and adaptive immunity. It may be that the main explanation for recurrent AOM in the first years of life is PNIP. Scientists from Australia also reported immunity problems in Aboriginal children and they are very otitis prone, often progressing to chronic suppurative otitis media. Animal model studies of AOM show inadequate innate and adaptive immunity importantly contribute to the infection as well.
Dr. Pichichero is a specialist in pediatric infectious diseases and director of the Research Institute at Rochester (N.Y.) General Hospital. He has no conflicts to declare. Email him at [email protected].