Recurrent acute otitis media occurring within one month from completion of antibiotic therapy: relationship to the original pathogen

The clinical implications of bacterial pathogenesis and mucosal immunity in chronic urinary tract infection

Urinary tract infections (UTIs) exert a significant health and economic cost globally. Approximately one in four people with a previous history of UTI continue to develop recurrent or chronic infections. Research on UTI has primarily concentrated on pathogen behavior, with the focus gradually shifting to encompass the host immune response. However, these are centered on mouse models of Escherichia coli infection, which may not fully recapitulate the infective etiology and immune responses seen in humans. The emerging field of the urobiome also inadvertently confounds the discrimination of true UTI-causing pathogens from commensals. This review aims to present a novel perspective on chronic UTI by linking microbiology with immunology, which is commonly divergent in this field of research. It also describes the challenges in understanding chronic UTI pathogenesis and the human bladder immune response, largely conjectured from murine studies. Lastly, it outlines the shortcomings of current diagnostic methods in identifying individuals with chronic UTI and consequently treating them, potentially aggravating their disease due to mismanagement of prior episodes. This discourse highlights the need to consider these knowledge gaps and encourages more relevant studies of UTIs in humans.

Association of e-Cigarette Exposure with Pediatric Otitis Media Recurrence

OBJECTIVE

Otitis media (OM) is a common inflammatory disease spectrum in children and a leading cause of pediatric physician visits, antibiotic prescriptions and surgery. Tobacco exposure is associated with increased risk of OM recurrence, chronicity and surgeries. Tobacco products have changed dramatically in recent years with the advent of electronic cigarettes (e-cigarettes). While users frequently perceive vape as less harmful than traditional cigarettes, burgeoning evidence supports its contribution to respiratory pathologies. The consequences of secondhand exposure, particularly among children, are understudied. The aim of this study was to examine the association of e-cigarette emissions (EE) with OM recurrence and surgeries in the US.

METHODS

Questionnaire data regarding ear infections and tobacco exposure was gathered for all pediatric respondents of the National Health and Nutrition Examination Survey (NHANES) 2017 to 2018. Weighted analyzes and logistic regression models were used to assess associations.

RESULTS

Data was available for 2022 participants (aged 6-17); all were included for analyzes. Tobacco exposure was observed in 42%; 9% were exposed to EE. EE contributed to risk of ≥3 ear infections (OR = 1.61, 95% CI 1.01-2.58, P = .047). After adjustment for significant covariates (race and asthma), the association fell below significance (P = .081). No other significant associations were observed between ear infections, or tympanostomy tube insertion and exposure variables (EE, gestational or other household exposure).

CONCLUSIONS

Exposure to EE may confer greater risk of pediatric OM than previously identified factors such as household smoke, or gestational exposure. Further investigation of EE and its health implications in children is warranted.

LEVEL OF EVIDENCE

IV.

Characteristics of acute otitis media in primary care are associated with tympanostomy tube outcomes

Objective

To identify characteristics of acute otitis media (AOM) at primary care presentation associated with TT placement and outcomes.

Methods

A retrospective cohort study of pediatric patients (birth-12 years old) with AOM at an academic primary care pediatric practice and affiliated tertiary referral free-standing Children's hospital from August 1, 2017 to December 31, 2019 was performed. The outcomes measured were TT placement, postoperative otorrhea, need for additional tube placement, and other complications (i.e., perforation and/or granulation).

Results

The 3189 patients were included, 484 of whom were referred to otolaryngology. Multivariate logistic regression analysis revealed that a greater number of AOM episodes diagnosed at primary care was associated with tube placement (OR = 1.21; 95% CI, 1.04-1.41, p = .02). Of the 336 patients who received tubes, older age at first AOM diagnosis was associated with postoperative otorrhea (OR = 1.02; 95% CI, 1.01-1.03; p = .001) and additional tube placement (OR = 1.03; 95% CI, 1.02-1.04; p < .001). Older age was also associated with other complications (OR = 1.02; 95% CI, 1.01-1.03; p = .001) by univariate analysis. Additionally, postoperative otorrhea was more common among patients who first received an AOM diagnosis at primary care in the spring (OR = 2.69; 95% CI, 1.37-5.29; p = .004), summer (OR = 2.88; 95% CI, 1.46-5.69; p = .002), and fall (OR = 2.18; 95% CI, 1.20-3.96; p = .01) seasons.

Conclusions

Clinical data from pediatric primary care visits found older age at first AOM diagnosis and having a first AOM diagnosis outside of winter to be associated with a more complicated eventual disease course.

Level of evidence

3-cohort study.

Ceftriaxone use for acute otitis media: Associated factors in a large U.S. primary care population

BACKGROUND

Clinicians in the authors' primary care academic practice have anecdotally perceived an increased use of intramuscular (IM) ceftriaxone, particularly for otitis-conjunctivitis in recent years (pre-pandemic). Increasing rates of ceftriaxone administration for acute otitis media (AOM) may be an important marker of antimicrobial resistance.

OBJECTIVE

We aimed to characterize the population of patients who received ceftriaxone for treatment of AOM, testing our hypothesis that patients with concomitant conjunctivitis would have increased rates of ceftriaxone receipt.

DESIGN/METHODS

We reviewed cases of AOM at a large U.S. primary care practice from August 2017 to July 2019. We determined the association between each of the following variables and ceftriaxone injection using multivariate analysis: age at AOM diagnosis, provider type, insurance (public vs private), season of year, and presence of conjunctivitis.

RESULTS

There were 6028 AOM episodes in 5195 patients resulting in a total of 7688 patient encounters. Of these episodes, 642 (10.7%) had a concurrent diagnosis of conjunctivitis; 362 (6.0%) ultimately received ceftriaxone. Conjunctivitis was the strongest predictor of treatment with ceftriaxone. The proportion of episodes with conjunctivitis treated with ceftriaxone was 14.5% (93/642) versus 5.0% (269/5386) without conjunctivitis (p < 0.0001). Patients who received ceftriaxone were younger; mean age (SD) for patients receiving ceftriaxone was 14.0 (8.8) months versus 25.0 (23.4) months (p < 0.0001).

CONCLUSION(S)

There is a strong correlation between the presence of conjunctivitis and receipt of IM ceftriaxone in this large U.S. academic primary care clinic. Younger age was also associated with ceftriaxone treatment. Further study on emerging resistance patterns and implications for management of AOM in young children is warranted.

[Current views on the treatment and prevention of recurrent acute otitis media in children (review of clinical recommendations)]

Recurrent acute otitis media (RAOM) represents at least 3 or more separate episodes of acute otitis media within 6 months or four or more episodes over a 12-month period. The incidence of recurrent otitis media varies from 5 to 30% and does not tend to decrease. Until now, the questions of conservative and surgical treatment of patients remain unsolved. One of the main methods of treatment is antimicrobial therapy. Recently, the treatment of recurrent otitis media is complicated by the increasing acquired resistance of bacteria to antimicrobial drugs. There is also no consensus on the need for and scope of surgical interventions for children with RAOM. The authors in their article cite existing modern approaches to the prevention and treatment of RAOM in children.

[Risk factors and clinical features of the course of recurrent acute otitis media in children]

This article discusses the problem of recurrent acute otitis media (RAOM) in children.

OBJECTIVE

To study the risk factors and the clinical course of RAOM in children.

MATERIAL AND METHODS

148 children (81 boys and 67 girls) from 1 to 14 years old were examined with a diagnosis of recurrent otitis media. The work was carried out in the ENT departments of Pediatric Clinical Hospital No. 13 named after N.F. Filatov, Pediatric Clinical Hospital named after Z.A. Bashlyaeva. The average age of the children was 4.1±1.5 years.

All children underwent a clinical study, a laboratory study on the content of the main metabolite of vitamin D - 25(OH)D₃ (25-hydroxyvitamin D, or calcidiol) in blood serum.

RESULTS

Our clinical examination of children with RAOM allows us to identify the main risk factors for this pathology. Thus, the most significant risk factors for the development of RAOM in children included in the study were: early visits by children to preschool institutions (50.6%), allergic history (39.1%), pathology during pregnancy (28.3%), mixed (38.5%) or artificial (27.7%) feeding in the first year of life, frequent upper respiratory tract diseases (41.2%), burdened heredity in close relatives according to RAOM (33.7%), smoking in the family of one of the parents (65.5%) presence in the family of one more child (34.4%).

CONCLUSION

It was shown that the absolute number of children (96%) with RAOM is characterized by a reduced level of 25(OH) vitamin D in the blood serum, which can increase the likelihood of developing episodes of acute otitis media in children and requires therapeutic correction.

Discovery of Small-Molecule VapC1 Nuclease Inhibitors by Virtual Screening and Scaffold Hopping from an Atomic Structure Revealing Protein-Protein Interactions with a Native VapB1 Inhibitor

Nontypeable Haemophilus influenzae (NTHi) are clinically important Gram-negative bacteria that are responsible for various human mucosal diseases, including otitis media (OM). Recurrent OM caused by NTHi is common, and infections that recur less than 2 weeks following antimicrobial therapy are largely attributable to the recurrence of the same strain of bacteria. Toxin-antitoxin (TA) modules encoded by bacteria enable rapid responses to environmental stresses and are thought to facilitate growth arrest, persistence, and tolerance to antibiotics. The vapBC-1 locus of NTHi encodes a type II TA system, comprising the ribonuclease toxin VapC1 and its cognate antitoxin VapB1. The activity of VapC1 has been linked to the survival of NTHi during antibiotic treatment both in vivo and ex vivo. Therefore, inhibitors of VapC1 might serve as adjuvants to antibiotics, preventing NTHi from entering growth arrest and surviving; however, none have been reported to date. A truncated VapB1 peptide from a crystal structure of the VapBC-1 complex was used to generate pharmacophore queries to facilitate a scaffold hopping approach for the identification of small-molecule VapC1 inhibitors. The National Center for Advancing Translational Sciences small-molecule library was virtually screened using the shape-based method rapid overlay of chemical structures (ROCS), and the top-ranking hits were docked into the VapB1 binding pocket of VapC1. Two hundred virtual screening hits with the best docking scores were selected and tested in a biochemical VapC1 activity assay, which confirmed eight compounds as VapC1 inhibitors. An additional 60 compounds were selected with structural similarities to the confirmed VapC1 inhibitors, of which 20 inhibited VapC1 activity. Intracellular target engagement of five inhibitors was indicated by the destabilization of VapC1 within bacterial cells from a cellular thermal shift assay; however, no impact on bacterial growth was observed. Thus, this virtual screening and scaffold hopping approach enabled the discovery of VapC1 ribonuclease inhibitors that might serve as starting points for preclinical development.

Tympanostomy Tubes or Medical Management for Recurrent Acute Otitis Media

BACKGROUND

Official recommendations differ regarding tympanostomy-tube placement for children with recurrent acute otitis media.

METHODS

We randomly assigned children 6 to 35 months of age who had had at least three episodes of acute otitis media within 6 months, or at least four episodes within 12 months with at least one episode within the preceding 6 months, to either undergo tympanostomy-tube placement or receive medical management involving episodic antimicrobial treatment. The primary outcome was the mean number of episodes of acute otitis media per child-year (rate) during a 2-year period.

RESULTS

In our main, intention-to-treat analysis, the rate (±SE) of episodes of acute otitis media per child-year during a 2-year period was 1.48±0.08 in the tympanostomy-tube group and 1.56±0.08 in the medical-management group (P = 0.66). Because 10% of the children in the tympanostomy-tube group did not undergo tympanostomy-tube placement and 16% of the children in the medical-management group underwent tympanostomy-tube placement at parental request, we conducted a per-protocol analysis, which gave corresponding episode rates of 1.47±0.08 and 1.72±0.11, respectively. Among secondary outcomes in the main analysis, results were mixed. Favoring tympanostomy-tube placement were the time to a first episode of acute otitis media, various episode-related clinical findings, and the percentage of children meeting specified criteria for treatment failure. Favoring medical management was children's cumulative number of days with otorrhea. Outcomes that did not show substantial differences included the frequency distribution of episodes of acute otitis media, the percentage of episodes considered to be severe, and antimicrobial resistance among respiratory isolates. Trial-related adverse events were limited to those included among the secondary outcomes of the trial.

CONCLUSIONS

Among children 6 to 35 months of age with recurrent acute otitis media, the rate of episodes of acute otitis media during a 2-year period was not significantly lower with tympanostomy-tube placement than with medical management. (Funded by the National Institute on Deafness and Other Communication Disorders and others; ClinicalTrials.gov number, NCT02567825.).

Early Life Microbiota and Respiratory Tract Infections

Over the last decade, it has become clear that respiratory and intestinal tract microbiota are related to pathogenesis of respiratory tract infections (RTIs). Host and environmental factors can drive respiratory microbiota maturation in early life, which in turn is related to consecutive susceptibility to RTIs. Moreover, during RTIs, including viral bronchiolitis, the local microbiome appears to play an immunomodulatory role through complex interactions, though causality has not yet been fully demonstrated. The microbiota is subsequently associated with recovery after RTIs and can be related to persistent or long-term sequelae. In this Review, we explore the epidemiological evidence supporting these associations and link to mechanistic insights. The long-term consequences of childhood RTIs and the comprehensive role of the microbiota at various stages in RTI pathogenesis call for early life preventative and therapeutic interventions to promote respiratory health.

Advances in Optical Detection of Human-Associated Pathogenic Bacteria

Bacterial infection is a global burden that results in numerous hospital visits and deaths annually. The rise of multi-drug resistant bacteria has dramatically increased this burden. Therefore, there is a clinical need to detect and identify bacteria rapidly and accurately in their native state or a culture-free environment. Current diagnostic techniques lack speed and effectiveness in detecting bacteria that are culture-negative, as well as options for in vivo detection. The optical detection of bacteria offers the potential to overcome these obstacles by providing various platforms that can detect bacteria rapidly, with minimum sample preparation, and, in some cases, culture-free directly from patient fluids or even in vivo. These modalities include infrared, Raman, and fluorescence spectroscopy, along with optical coherence tomography, interference, polarization, and laser speckle. However, these techniques are not without their own set of limitations. This review summarizes the strengths and weaknesses of utilizing each of these optical tools for rapid bacteria detection and identification.

The effect of pneumococcal conjugate vaccines on otitis media from 2005 to 2013 in children aged ≤5 years: a retrospective cohort study in two Swedish regions

Seven-valent pneumococcal conjugate vaccine (PCV7) was introduced to Sweden in 2009 and replaced by pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) or 13-valent PCV (PCV13) from late 2009. A retrospective cohort study assessed the impact of PCVs on otitis media/acute otitis media (OM) in children aged ≤5 years (NCT02742753) living in Skåne (PCV7 then PHiD-CV) or Västra Götalandsregionen (PCV7 then PCV13) between 2005 and 2013 using linked regional and national databases. Time-series analyses described differences between pre-PCV and post-PCV eras. Adjusted age-period-cohort (APC) predictive models estimated vaccine effectiveness and OM incidence ratios between PCV cohorts. Time-to-first OM diagnosis was estimated in ≤2 year-olds by survival analysis using a Cox proportional hazards model. Descriptive interrupted time-series analyses showed OM incidence in ≤2 year-olds declined by 42% (Skåne) and 25% (Västra Götalandsregionen) after PHiD-CV/PCV13, respectively, versus pre-PCV, but baseline OM incidence and duration of PCV7 use differed between regions. In adjusted APC models, OM incidence decreased after PHiD-CV by 9.9% (95% confidence interval [CI]: 4.4; 15.1, p < .001) and PCV13 by 2.3% (95%CI: −3.2; 7.6, p = .401) compared with pre-PCV. Both PHiD-CV and PCV13 decreased the risk of first OM diagnosis: hazard ratio (95%CI) for PHiD-CV relative to pre-PCV 0.67 (0.65; 0.69); 0.87 (0.85; 0.89) for PCV13 relative to pre-PCV; p < .001 for both comparisons. Within the limitations of this study conducted in two large Swedish regions, descriptive time-series analyses showed that OM incidence rates declined following the introduction of PHiD-CV and PCV13; however, this reduction only reached statistical significance for PHiD-CV in the adjusted APC models.

Moraxella catarrhalis Promotes Stable Polymicrobial Biofilms With the Major Otopathogens

Otitis media (OM) is a prevalent pediatric infection characterized by painful inflammation of the middle ear. The Gram-negative diplococcus Moraxella catarrhalis is a commensal of the nasopharynx and one of three leading causative agents of OM. The most recent work on this multifaceted disease indicates that biofilms and polymicrobial infections play a pivotal role in recurrent and chronic OM, which are difficult to eradicate using standard antibiotic protocols. Although there have been significant advances in OM research, the actual bacterial and viral interactions leading to pathogenesis remain largely uncharacterized. However, colonization and persistence in the nasopharynx is clearly an essential first step. In this study, we assessed the role M. catarrhalis plays in the co-colonization and persistence of the other major otopathogens, Streptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi). We characterized both monomicrobial and polymicrobial biofilms using an in vitro nasopharyngeal colonization model. Biofilm assays were designed to mimic the nasopharynx and bacterial persistence was quantified over time. NTHi showed a steady and significant decline in viability over 20–48 h when this organism was in a dual species biofilm with S. pneumoniae. However, when M. catarrhalis was present in the polymicrobial biofilm NTHi survived for 48 h at 10⁷ CFU per mL. In addition, an isogenic M. catarrhalis catalase-deficient mutant was also fully capable of protecting NTHi from the bactericidal activity of S. pneumoniae in a polymicrobial biofilm. Our results show that M. catarrhalis promotes a favorable environment for stable polymicrobial biofilms by enhancing the survival of NTHi in the presence of S. pneumoniae. These data suggest that colonization with M. catarrhalis promotes stable co-colonization with other otopathogens.

Contribution of the Mucosal Microbiota to Bovine Respiratory Health

Recognizing the respiratory tract as a dynamic and complex ecosystem has enhanced our understanding of the pathophysiology of bovine respiratory disease (BRD). There is widespread evidence showing that disease-predisposing factors often disrupt the respiratory microbial ecosystem, provoking atypical colonization patterns and a progressive dysbiosis. The ecological factors that shape the respiratory microbiota, and the influence of these complex communities on bovine respiratory health, are a rich area for research exploration. Here, we review the current status of understanding of the bovine respiratory microbiota, the factors that influence its development and stability, its role in maintaining mucosal homeostasis, and ultimately its contribution to bovine health and disease. Finally, we explore the limitations of current research approaches to the microbiome and discuss potential directions for future research that can help us better understand the role of the respiratory microbiota in the health, welfare, and productivity of livestock.

Antimicrobial Effects on Swine Gastrointestinal Microbiota and Their Accompanying Antibiotic Resistome

Antimicrobials are the most commonly prescribed drugs in the swine industry. While antimicrobials are an effective treatment for serious bacterial infections, their use has been associated with major adverse effects on health. It has been shown that antimicrobials have substantial direct and indirect impacts on the swine gastrointestinal (GI) microbiota and their accompanying antimicrobial resistome. Antimicrobials have also been associated with a significant public health concern through selection of resistant opportunistic pathogens and increased emergence of antimicrobial resistance genes (ARGs). Since the mutualistic microbiota play a crucial role in host immune regulation and in providing colonization resistance against potential pathogens, the detrimental impacts of antimicrobial treatment on the microbiota structure and its metabolic activity may lead to further health complications later in life. In this review, we present an overview of antimicrobial use in the swine industry and their role in the emergence of antimicrobial resistance. Additionally, we review our current understanding of GI microbiota and their role in swine health. Finally, we investigate the effects of antimicrobial administration on the swine GI microbiota and their accompanying antibiotic resistome. The presented data is crucial for the development of robust non-antibiotic alternative strategies to restore the GI microbiota functionality and guarantee effective continued use of antimicrobials in the livestock production system.

Prevention of Recurrent Acute Otitis Media in Children Through the Use of Lactobacillus salivarius PS7, a Target-Specific Probiotic Strain

Acute otitis media (AOM) is one of the most common bacterial infections in children. Empiric antibiotherapy leads to increasing antimicrobial resistance rates among otopathogens and may impair the correct development of the microbiota in early life. In this context, probiotics seem to be an attractive approach for preventing recurrent AOM (rAOM) through the restoration of the middle ear and nasopharyngeal microbiota. The aim of this study was the selection of a probiotic strain (Lactobacillus salivarius PS7), specifically tailored for its antagonism against otopathogens. Since L. salivarius PS7 was safe and displayed a strong antimicrobial activity against otopathogens, its efficacy in preventing rAOM was assessed in a trial involving 61 children suffering from rAOM. Children consumed daily ~1 × 10⁸ CFU of L. salivarius PS7, and the number of AOM episodes were registered and compared with that observed in the previous 6 and 12 months. The microbiota of samples collected from the external auditory canal samples was quantitatively and qualitatively assessed. The number of AOM episodes during the intervention period decreased significantly (84%) when compared to that reported during the 6 months period before the probiotic intervention. In conclusion, L. salivarius PS7 is a promising strain for the prevention of rAOM in infants and children.

Effectiveness of 13-valent pneumococcal conjugate vaccination for protection against acute otitis media caused by Streptococcus pneumoniae in healthy young children: a prospective observational study

BACKGROUND

With wide use of the seven-valent pneumococcal conjugate vaccine (PCV7) for protection against acute otitis media caused by Streptococcus pneumoniae serotypes included in the vaccine, efficacy testing for the 13-valent vaccine (PCV13) was not feasible. We aimed to assess the effectiveness of PCV13 in preventing acute otitis media caused by the six serotypes in PCV13 that were not in PCV7.

METHODS

We did a longitudinal observational study in healthy children seen as outpatients in a private paediatric practice in Rochester, NY, USA. Children aged up to 30 months who had received the full primary series of PCV13 with other recommended vaccines were eligible to participate and were followed up to age 30-36 months to identify episodes of acute otitis media, during which we collected middle-ear fluid (MEF) by tympanocentesis. We assessed MEF for the serotypes common to PCV7 and PCV13 (4, 6B, 9V, 14, 18C, 19F, and 23F) and the six additional serotypes specific to PCV13 (1, 3, 5, 6A, 7F, and 19A). As controls, we included children enrolled in a longitudinal study in the study centre from Oct 1, 2007, to Sept 30, 2009, who had been vaccinated with PCV7, had MEF prospectively collected at the onset of acute otitis media, and been followed up until age 30 months. The primary outcome was the effectiveness of PCV13 to prevent acute otitis media caused by pneumococci expressing the six capsular serotypes not included in PCV7 (1, 3, 5, 6A, 7F, and 19A). This study is registered with ClinicalTrials.gov, number NCT01199016.

FINDINGS

From Sept 28, 2010, to Sept 30, 2013, we enrolled 239 children (123 [51%] boys and 116 [49%] girls; median age 6·3 months [IQR 6·1-8·6]) in the PCV13 cohort, and 162 completed the study. Of 348 children (184 [53%] boys and 164 [47%] girls; 6·5 months [6·1-9·1]) included in the PCV7 cohort, 248 completed follow-up. 223 MEF samples were obtained at onset of acute otitis media from 90 children in the PCV13 cohort. 53 (24%) of 223 samples were culture positive for S pneumoniae, compared with 89 (31%) of 284 samples in the PCV7 cohort (p=0·06). Four (8%) of 53 samples in the PCV13 cohort contained pneumococci expressing one of the additional PCV13 capsular serotypes, compared with 46 (52%) of 89 samples in the PCV7 cohort, giving a relative reduction of 86% (95% CI 61-94, p=0·0010). The greatest reduction in MEF samples was in serotype 19A (two [4%] in the PCV13 cohort vs 46 [52%] in the PCV7 cohort; relative reduction 91% [58-97, p=0·0010]).

INTERPRETATION

PCV13 prevents acute otitis media caused by S pneumoniae expressing serotypes included in the vaccine.

FUNDING

Pfizer.

The microbiota of the respiratory tract: gatekeeper to respiratory health

The respiratory tract is a complex organ system that is responsible for the exchange of oxygen and carbon dioxide. The human respiratory tract spans from the nostrils to the lung alveoli and is inhabited by niche-specific communities of bacteria. The microbiota of the respiratory tract probably acts as a gatekeeper that provides resistance to colonization by respiratory pathogens. The respiratory microbiota might also be involved in the maturation and maintenance of homeostasis of respiratory physiology and immunity. The ecological and environmental factors that direct the development of microbial communities in the respiratory tract and how these communities affect respiratory health are the focus of current research. Concurrently, the functions of the microbiome of the upper and lower respiratory tract in the physiology of the human host are being studied in detail. In this Review, we will discuss the epidemiological, biological and functional evidence that support the physiological role of the respiratory microbiota in the maintenance of human health.

Host-pathogen interactions of nontypeable Haemophilus influenzae: from commensal to pathogen

Nontypeable Haemophilus influenzae (NTHi) is a commensal microbe often isolated from the upper and lower respiratory tract. This bacterial species can cause sinusitis, acute otitis media in preschool children, exacerbations in patients suffering from chronic obstructive pulmonary disease, as well as conjunctivitis and bacteremia. Since the introduction of a vaccine against H. influenzae serotype b in the 1990s, the burden of H. influenzae-related infections has been increasingly dominated by NTHi. Understanding the ability of NTHi to cause infection is currently an expanding area of study. NTHi is able to exert differential binding to the host tissue through the use of a broad range of adhesins. NTHi survival in the host is multifaceted, that is, using virulence factors involved in complement resistance, biofilm, modified immunoglobulin responses, and, finally, formation and utilization of host proteins as a secondary strategy of increasing the adhesive ability.

The role of the local microbial ecosystem in respiratory health and disease

Respiratory tract infections are a major global health concern, accounting for high morbidity and mortality, especially in young children and elderly individuals. Traditionally, highly common bacterial respiratory tract infections, including otitis media and pneumonia, were thought to be caused by a limited number of pathogens including Streptococcus pneumoniae and Haemophilus influenzae. However, these pathogens are also frequently observed commensal residents of the upper respiratory tract (URT) and form-together with harmless commensal bacteria, viruses and fungi-intricate ecological networks, collectively known as the 'microbiome'. Analogous to the gut microbiome, the respiratory microbiome at equilibrium is thought to be beneficial to the host by priming the immune system and providing colonization resistance, while an imbalanced ecosystem might predispose to bacterial overgrowth and development of respiratory infections. We postulate that specific ecological perturbations of the bacterial communities in the URT can occur in response to various lifestyle or environmental effectors, leading to diminished colonization resistance, loss of containment of newly acquired or resident pathogens, preluding bacterial overgrowth, ultimately resulting in local or systemic bacterial infections. Here, we review the current body of literature regarding niche-specific upper respiratory microbiota profiles within human hosts and the changes occurring within these profiles that are associated with respiratory infections.

The role of the local microbial ecosystem in respiratory health and disease

Respiratory tract infections are a major global health concern, accounting for high morbidity and mortality, especially in young children and elderly individuals. Traditionally, highly common bacterial respiratory tract infections, including otitis media and pneumonia, were thought to be caused by a limited number of pathogens including Streptococcus pneumoniae and Haemophilus influenzae. However, these pathogens are also frequently observed commensal residents of the upper respiratory tract (URT) and form-together with harmless commensal bacteria, viruses and fungi-intricate ecological networks, collectively known as the 'microbiome'. Analogous to the gut microbiome, the respiratory microbiome at equilibrium is thought to be beneficial to the host by priming the immune system and providing colonization resistance, while an imbalanced ecosystem might predispose to bacterial overgrowth and development of respiratory infections. We postulate that specific ecological perturbations of the bacterial communities in the URT can occur in response to various lifestyle or environmental effectors, leading to diminished colonization resistance, loss of containment of newly acquired or resident pathogens, preluding bacterial overgrowth, ultimately resulting in local or systemic bacterial infections. Here, we review the current body of literature regarding niche-specific upper respiratory microbiota profiles within human hosts and the changes occurring within these profiles that are associated with respiratory infections.

Payment analysis of two diagnosis and management approaches of acute otitis media

We determined the cost of care for 2 diagnosis and management approaches for acute otitis media (AOM) among children 6 to 30 months old. A case-control design was used. Cases included 208 children diagnosed with AOM based on a bulging tympanic membrane (TM) and treated with amoxicillin/clavulanate. Controls (5:1 ratio) included 1020 children with AOM diagnosed not requiring bulging of the TM and treated with amoxicillin. Fewer cases (49%) than controls (69%) were diagnosed with AOM (P < .001), fewer were diagnosed with recurrent AOM or AOM treatment failure (0.34 vs 1.6/child; P < .0001), and fewer had insertion of tympanostomy tubes (6.3% vs 14.8%) due to recurrent AOM (P < .0001). The combined direct payments and indirect costs for management of AOM were $539/case versus $1,023/control. Using Rochester NY payments generalized to the US birth cohort, this case diagnosis and treatment strategy could save $1.008 billion per year.

Relationship with original pathogen in recurrence of acute otitis media after completion of amoxicillin/clavulanate: bacterial relapse or new pathogen

OBJECTIVE

We sought to determine whether recurrent acute otitis media (rAOM) occurring within 30 days of amoxicillin/clavulanate treatment was caused by bacterial relapse or new pathogens.

METHODS

Pneumococcal conjugate vaccinated children, age 6-36 months, enrolled in a prospective, longitudinal study experiencing rAOM<1 month after completing amoxicillin/clavulanate therapy were studied. AOM episodes occurred between June 2006 and November 2012. Multilocus sequence typing was used to genotype isolates.

RESULTS

Sixty-six children were in the study cohort; 63 otopathogens were recovered from middle ear fluid after tympanocentesis. Nontypeable Haemophilus influenzae (NTHi) accounted for 47% of initial AOMs versus 15% by Streptococcus pneumoniae (Spn), P<0.0001. NTHi accounted for 42% of rAOM versus 24% by Spn (P value=0.04). NTHi was the main otopathogen that caused true bacteriologic relapses (77%). β-lactamase-producing NTHi and penicillin nonsusceptible Spn were not more common in rAOM than initial AOM infections. Among 21 paired (initial and rAOM events) NTHi isolates genotyped, 13 (61.9%) were the same organism; 1 of 9 (11.1%) of paired Spn isolates was the same (P value=0.017). rAOM occurring within a week of stopping amoxicillin/clavulanate was a different pathogen in 21% of cases, 8-14 days later in 33%, 15-21 days in 41% and 22-30 days in 57% (P=0.04).

CONCLUSIONS

In amoxicillin/clavulanate-treated children, NTHi was the main otopathogen that caused true bacteriologic relapses. New pathogens causing rAOM versus persistence of the initial pathogen significantly increased week to week. Neither relapses nor new infections were caused more frequently by β-lactamase producing NTHi or penicillin nonsusceptible Spn.

Panel 7: Treatment and comparative effectiveness research

BACKGROUND AND OBJECTIVES

Otitis media (OM) is one of the most common reasons for antibiotic treatment in children. Controversies regarding antibiotic treatment for OM have accumulated in the past decade, and there seem to be more dilemmas than certainties. The objectives of this article are to provide the state-of-the art review on achievements in treatment of all different stages of OM, including acute otitis media (AOM), otitis media with effusion (OME), and chronic suppurative otitis media, and to outline the future research areas.

DATA SOURCES

PubMed, Ovid Medline, the Cochrane Database, and Clinical Evidence (BMJ Publishing).

REVIEW METHODS

All types of articles related to OM treatment published in English between January 2007 and June 2011 were identified. A total of 286 articles related to OM treatment were reviewed by the panel members; 114 relevant quality articles were identified and summarized.

RESULTS

New evidence emerged on beneficial results of antibiotic treatment, compared with observation of AOM in young children who were diagnosed based on stringent criteria. In OME, the main results were related to a nonsignificant benefit of adenoidectomy versus tympanostomy tube placement alone in the treatment of chronic OME in younger children. Other modalities of OM treatment were studied and described herein.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

Significant progress has been made in advancing the knowledge on the treatment of OM. Areas of potential future research have been identified and outlined.

Reducing the frequency of acute otitis media by individualized care

OBJECTIVE

We sought to determine if use of more stringent diagnostic criteria for acute otitis media (AOM) than currently advocated by the American Academy of Pediatrics, tympanocentesis and pathogen-specific antibiotic treatment (individualized care) would result in reducing the incidence of recurrent AOM and consequent tympanostomy tube surgery.

METHODS

A 5-year longitudinal, prospective study in Rochester, NY, was conducted from July 2006 to July 2011 involving 254 individualized care children. When this individualized care group developed symptoms of AOM, strict diagnostic criteria were applied and a tympanocentesis was performed. Pathogen resistance to empiric high-dose amoxicillin/clavulanate (80 mg/kg of amoxicillin component) caused a change in antibiotic to an optimized choice. Legacy controls (n = 208) were diagnosed with the same diagnostic criteria by the same physicians as the individualized care group and received the same empiric amoxicillin/clavulanate (80 mg/kg of amoxicillin component) but no tympanocentesis or change in antibiotic. Community control children (n = 1020) were diagnosed according to current American Academy of Pediatrics guidelines and treated with high-dose amoxicillin (80 mg/kg) without tympanocentesis as guideline recommended.

RESULTS

5.9% of children of the individualized care group compared with 14.4% of Legacy controls and 27.3% of community controls became otitis prone, defined as 3 episodes of AOM within a 6-month time span or 4 AOM episodes within a 12-month time span (P < 0.0001). 2.4% of the individualized care group compared with 6.3% of Legacy controls, and 14.8% of community controls received tympanostomy tubes (P < 0.0001).

CONCLUSIONS

Individualized care of AOM significantly reduces the frequency of AOM and tympanostomy tube surgery. Use of strict diagnostic criteria for AOM and empiric antibiotic treatment using evidence-based knowledge of circulating otopathogens and their antimicrobial susceptibility profile also produces improved outcomes.

Earache

Earache, a common emergency department presentation, may be caused by a variety of conditions, some distant from the ear. This article discusses the diagnosis and treatment of acute otitis media, otitis media with effusion, otitis externa, otitis media with ruptured tympanic membrane or tympanostomy tubes, malignant otitis externa, mastoiditis and petrositis, traumatic ruptured tympanic membrane, cerumen impactions, and foreign bodies in the ears.

A retrospective evaluation of microbiology of acute otitis media complicated by spontaneous otorrhea in children living in Milan, Italy

PURPOSE

To evaluate the microbiology of acute otitis media (AOM) with otorrhea due to spontaneous tympanic membrane perforation (STMP) in children living in Milan, Italy.

METHODS

We evaluated middle ear fluid (MEF) specimens taken from children affected by AOM associated with STMP and otorrhea between January 2001 and December 2011. The fluid was collected by means of direct swab sampling, sent for culture, and processed within 4 h.

RESULTS

A total of 705 specimens were obtained from 458 children (233 boys; mean age ± SD 28.3 ± 19.9 months), and were positive for bacteria in 487 cases (69.1 %). The most frequently cultured infectious agent in single-pathogen cultures was Haemophilus. influenzae (51.0 %), followed by Streptococcus pneumoniae (19.4 %), Streptococcus pyogenes (17.4 %), and Staphylococcus aureus (10.7 %). After adjusting for the sub-period of data collection, age, gender, and previous full heptavalent pneumococcal conjugate vaccine (PCV-7) schedule, it was found that the prevalence of H. influenzae slightly increased in 2008-2010, and the prevalence of S. pneumoniae significantly decreased over time (p = 0.02).

CONCLUSIONS

AOM with STMP is a particular form of AOM in which S. pyogenes plays a significant causative role although, as in uncomplicated cases, H. influenzae and S. pneumoniae retain their etiological importance. The frequency of the detection of S. aureus in MEF deserves further study because this pathogen can give rise to severe clinical problems. Finally, although the use of PCV-7 was relatively efficacious, the benefit of pneumococcal vaccination would be increased by vaccines including a larger number of serotypes.

Pneumococcal vaccination in children at risk of developing recurrent acute otitis media - a randomized study

AIM

Acute otitis media (AOM) is a common childhood disease, which often becomes recurrent (rAOM). A small reduction in AOM episodes has been noted in unselected child cohorts after vaccination with heptavalent conjugate pneumococcal vaccine (PCV7). The purpose of this study was to investigate how vaccination affects young children at risk of developing rAOM.

METHODS

Ninety-six children with an AOM onset before 6 months of age, implying a high risk for rAOM, were closely monitored until the age of 2 years. Forty-six were vaccinated with PCV7 and 50 were not. All episodes of AOM, emergency visits and ventilation tube insertions were registered.

RESULTS

A total of 363 AOM episodes were diagnosed. The incidence was reduced by 26% (p = 0.03), the number of emergency visits because of suspected AOM by 36% (p = 0.01) and the proportion of children who received ventilation tubes was halved in the vaccine group (p = 0.02).

CONCLUSIONS

During the first 2 years of life, PCV7 significantly reduced AOM episodes, emergency visits and ventilation tube insertions in children with rAOM. Pneumococcal vaccine may be a future route to reduce antibiotic use and health care consumption in otitis-prone children.

Otitis media: viruses, bacteria, biofilms and vaccines

Otitis media typically presents as either acute otitis media (AOM), with symptoms including fever, otalgia, otorrhoea or irritability and short duration; or as otitis media with effusion (OME), which is often asymptomatic and characterised by accumulation of fluid in the middle ear.

Diagnostic certainty of otitis media is challenging, given the young age of patients and variability of symptoms.

Otitis media predominantly occurs as coincident to viral upper respiratory tract infections and/or bacterial infections.

Common viruses that cause upper respiratory tract infection are frequently associated with AOM and new‐onset OME. These include respiratory syncytial virus, rhinovirus, adenovirus, parainfluenza and coronavirus.

Predominant bacteria that cause otitis media are Streptococcus pneumoniae, Moraxella catarrhalis, and non‐typeable Haemophilus influenzae.

Antibiotic therapy does not significantly benefit most patients with AOM, but long‐term prophylactic antibiotic therapy can reduce the risk of otitis media recurrence among children at high risk.

In Australia, 84% of AOM is treated with antibiotic therapy, which contributes to development of antibiotic resistance.

Vaccine development is a key future direction for reducing the world burden of otitis media, but requires polymicrobial formulation and ongoing monitoring and modification to ensure sustained reduction in disease burden.

Recent advances in otitis media

Otitis media (OM) is a pervasive illness in infants and children, and many children suffer multiple episodes during the first years of life. High rates of acute otitis media (AOM) are reported in developed and emerging countries. Early onset is common in both settings. Recurrent OM is associated with several factors, including early onset of disease, having a sibling with a history of AOM and absence of breast-feeding. Early onset disease has been hypothesized to result from Eustachian tube dysfunction, immunologic naivete and immaturity, and viral upper respiratory tract infection. Nasopharyngeal colonization with bacterial otopathogens increases the likelihood of AOM and the disease is most frequent in children with viral respiratory tract infection colonized with multiple otopathogens (Streptococcus pneumoniae, nontypeable Haemophilus influenzae [NTHi], Moraxella catarrhalis), potentially as a result of inflammation resulting from competition among the bacterial species within the nasopharynx. Epidemiologic observations and studies of pathogenesis suggest that successful strategies for reducing the burden of disease will be best accomplished by targeting multiple viral and/or bacterial pathogens and preventing early onset disease. Guidelines (2004) for the treatment of AOM in children establish a clear hierarchy among the various antibacterials for the treatment of this disease. Failure to achieve early bacterial eradication during antibiotic therapy for AOM increases the clinical failure rates in AOM in young children. Most recurrent AOM episodes occurring within 1 month after successful completion of antibiotic therapy are due to new otopathogens. Failure to eradicate middle ear and/or nasopharyngeal pathogens is associated with higher rates of clinical recurrent AOM, even when the patients show clinical improvement or cure at the end of therapy for the initial episode. Optimal strategy for the prevention of AOM recurrences requires sterilization of the middle ear and eradication of nasopharyngeal carriage of otopathogens during antimicrobial therapy.

Epidemiologic and microbiologic characteristics of culture-positive spontaneous otorrhea in children with acute otitis media

OBJECTIVES

We aimed to describe the epidemiologic and microbiologic characteristics of acute otitis media (AOM) with spontaneous otorrhea in children and compare it with AOM with intact tympanic membrane in children who underwent tympanocentesis.

PATIENTS AND METHODS

All infants and young children aged <3 years with culture-positive AOM of < or =7 days duration diagnosed during 1999 to 2006 and in whom epidemiologic and microbiologic data were available, were analyzed. Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pyogenes were considered true AOM pathogens. Multivariable regression analysis models adjusting for age, gender, ethnicity, seasonality, previous antibiotics, AOM history, tympanocentesis history, and pathogens isolated, were used.

RESULTS

Of 12,617 AOM patients from whom a middle ear fluid was obtained, 5247 (42%) culture-positive patients were enrolled; spontaneous otorrhea was observed in 822 (15%) patients. Patients with spontaneous otorrhea were older than patients with AOM who underwent tympanocentesis (15.8 +/- 8.2 vs. 9.7 +/- 6.7 months, respectively, P < 0.01; 36.9% vs. 69.1%, respectively, were <12 months, P < 0.01). S. pyogenes was found in a higher proportion (47/822, 5.7% vs. 44/4425, 1%, P < 0.01) and H. influenzae in a lower proportion (264/822, 32.1% vs. 1805/4425, 40.8%, P < 0.01) among patients with spontaneous otorrhea than in patients with AOM and tympanocentesis. In the multivariate model, Bedouin ethnicity (OR: 1.5, 95% CI: 1.2-1.7, P < 0.001), age (OR: 1.1, 95% CI: 1.0-1.11, P < 0.001) for each consecutive month, lack of antibiotic treatment for the 48 hours preceding diagnosis (OR: 2.1, 95% CI: 1.7-2.6, P < 0.001), > or =1 previous AOM episode (OR: 3.2, 95% CI: 2.6-4.0, P < 0.001), >1 previous tympanocentesis (OR: 1.4, 95% CI: 1.4-1.7, P = 0.001), and infection with S. pyogenes (OR: 8.2, 95% CI: 5.4-12.3, P < 0.001) were independent risk factors for AOM presenting as spontaneous otorrhea.

CONCLUSIONS

AOM presenting as spontaneous otorrhea in patients less than 3 years of age is characterized by older age, previous repeated tympanocenteses, > or =1 previous AOM episodes, lack of recent antibiotic treatment, and infection with S. pyogene.

Comparison of study designs for acute otitis media trials

BACKGROUND

A framework for evaluating the efficacy of antibiotics in development as well as those currently approved for acute otitis media (AOM) is needed.

OBJECTIVE

Review strengths and limitations of various antibiotic trial designs and their outcome measures.

METHODS

A review of 157 published trials involving 36,710 subjects for the treatment of AOM.

RESULTS

AOM trials have three designs: (1) clinical, clinical diagnosis and assessment of outcomes; (2) single tympanocentesis, microbiologic diagnosis (by middle ear fluid culture) and clinical assessment of outcomes; and (3) double tympanocentesis, microbiologic diagnosis and microbiologic outcome assessment. Identifiable strengths and limitations of each design are reviewed. Case definitions for entry of children in trials of AOM vary widely. The lack of stringent diagnostic criteria in a clinical design allows for inclusion of a significant proportion of children with a non-bacterial etiology (i.e., viral AOM or otitis media with effusion). Tympanocentesis increases diagnostic accuracy at study entry; however, the procedure is confounding because of its potentially therapeutic benefit and the procedure is not performed in a uniform manner. A second tympanocentesis allows a high sensitivity to detect microbiologic eradication, but it does not correlate with clinical outcomes in half of the cases. The timing of outcome assessment also varies widely among trials.

CONCLUSIONS

Improved clinical diagnosis criteria for AOM are needed to enhance specificity; emphasis on a bulging tympanic membrane has the best evidence base. Tympanocentesis within study designs has merits. At study entry it assures diagnostic accuracy but may alter outcomes and it is useful to document microbiologic outcomes but lacks specificity for clinical outcomes. For all designs, test of cure assessment 2-7 days after completion of therapy seems most appropriate.

Persistence of pathogens despite clinical improvement in antibiotic-treated acute otitis media is associated with clinical and bacteriologic relapse

BACKGROUND

Pathogen eradication in patients with acute otitis media (AOM) is associated with a reduced risk of clinical failures, but most children in whom middle ear fluid (MEF) culture remains positive show clinical improvement or clinical cure. We investigated the relationship between MEF culture-positivity during treatment in patients with clinical improvement/cure, and the occurrence of subsequent AOM.

METHODS

A total of 673 patients with culture-positive MEF were enrolled in double-tympanocentesis studies and followed for 3 weeks after completion of treatment.

RESULTS

On day 4-6, 189/673 (28%) patients had culture-positive MEFs. Patients with clinical improvement/cure on day 11-14 (end of treatment) despite having culture-positive MEF on day 4-6 more often had recurrent AOM episodes (53/151, 35%) than those with culture-negative MEF (114/476, 24%; P = 0.007). 41/53 (77%) culture-positive patients with clinical improvement/cure on day 11-14 underwent tympanocentesis when AOM recurred and 29/41 (71%) were culture-positive. Pulsed field gel electrophoresis identity between pathogens at recurrence and those persisting on day 4-6 was found in 19/29 (66%) compared with 31/86 (36%) of the evaluable patients with recurrence and culture-negative MEF on day 4-6 (P = 0.005).

CONCLUSIONS

(1) Failure to eradicate MEF pathogens during antibiotic treatment is associated with clinical recurrences, even in patients showing clinical improvement/cure at end of treatment; (2) these recurrences are mostly caused by pathogens initially present in MEF and persisting during treatment.

The challenge of recalcitrant acute otitis media: pathogens, resistance, and treatment strategy

Recalcitrant acute otitis media (AOM), including 2 well-defined and sometimes related entities (persistent AOM and recurrent AOM), is a common pediatric problem. Episodes of AOM in children with either persistent or recurrent AOM were shown to be associated with recovery of middle ear fluid bacterial pathogens (particularly Streptococcus pneumoniae) with higher resistance to antibiotics compared with children with AOM not recently treated with antibiotics. The relationships between nasopharyngeal carriage of Streptococcus pneumoniae and persistence of middle ear fluid pathogens despite clinical improvement or cure and subsequent recurrence are discussed in depth. The findings emphasize the importance of bacteriologic eradication in the prevention of recurrent AOM episodes.

Multiple consecutive lavage samplings reveal greater burden of disease and provide direct access to the nontypeable Haemophilus influenzae biofilm in experimental otitis media

The typically recovered quantity of nontypeable Haemophilus influenzae (NTHi) bacteria in an ex vivo middle ear (ME) aspirate from the chinchilla model of experimental otitis media is insufficient for direct analysis of gene expression by microarray or of lipopolysaccharide glycoforms by mass spectrometry. This prompted us to investigate a strategy of multiple consecutive lavage samplings to increase ex vivo bacterial recovery. As multiple consecutive lavage samples significantly increased the total number of bacterial CFU collected during nasopharyngeal colonization or ME infection, this led us to evaluate whether bacteria sequentially acquired from consecutive lavages were similar. Comparative observation of complete ex vivo sample series by microscopy initially revealed ME inflammatory fluid consisting solely of planktonic-phase NTHi. In contrast, subsequent lavage samplings of the same infected ear revealed the existence of bacteria in two additional growth states, filamentous and biofilm encased. Gene expression analysis of such ex vivo samples was in accord with different bacterial growth phases in sequential lavage specimens. The existence of morphologically distinct NTHi subpopulations with varying levels of gene expression indicates that the pooling of specimens requires caution until methods for their separation are developed. This study based on multiple consecutive lavages is consistent with prior reports that NTHi forms a biofilm in vivo, describes the means to directly acquire ex vivo biofilm samples without sacrificing the animal, and has broad applicability for a study of mucosal infections. Moreover, this approach revealed that the actual burden of bacteria in experimental otitis media is significantly greater than was previously reported. Such findings may have direct implications for antibiotic treatment and vaccine development against NTHi.

Antibodies specific for the high-molecular-weight adhesion proteins of nontypeable Haemophilus influenzae are opsonophagocytic for both homologous and heterologous strains

The HMW1/HMW2-like adhesion proteins of nontypeable Haemophilus influenzae (NTHI) are expressed by 75% of NTHI strains. Antibodies directed against these proteins are opsonophagocytic in vitro and are protective in an animal model of infection. The objective of the present study was to determine the opsonophagocytic activity of high-titer anti-HMW1/HMW2 immune sera against both homologous and heterologous NTHI strains. Chinchillas were immunized with purified HMW1/HMW2-like proteins from five prototype NTHI strains. Serum opsonophagocytic activity was monitored in an assay that uses a human promyelocytic cell line, HL-60, as the source of phagocytic cells. Preimmune sera did not demonstrate opsonophagocytic killing of any strains. In contrast, the immune sera demonstrated killing of the five homologous NTHI strains at titers ranging from 1:320 to 1:640. The immune sera also demonstrated killing of eight heterologous NTHI strains that express HMW1/HMW2-like proteins at titers ranging from 0 to 1:640. Killing of heterologous strains sometimes demonstrated a prozone phenomenon. None of the immune sera killed NTHI strains that did not express HMW1/HMW2-like proteins. Adsorption of immune sera with HMW1/HMW2-like proteins purified from either homologous or heterologous NTHI strains eliminated opsonophagocytic killing of homologous strains in most cases. These data demonstrate that antibodies produced following immunization with the HMW1/HMW2-like proteins are opsonophagocytic for both homologous and heterologous NTHI and strongly suggest that common epitopes recognized by functionally active antibodies exist on the HMW1/HMW2-like proteins of unrelated NTHI strains. The results argue for the continued investigation of the HMW1/HMW2-like proteins as potential vaccine candidates for the prevention of NTHI disease.

Efficacy, tolerability, and parent reported outcomes for cefdinir vs. high-dose amoxicillin/clavulanate oral suspension for acute otitis media in young children

OBJECTIVES

To compare efficacy, tolerability, and parental satisfaction of cefdinir and high-dose amoxicillin/clavulanate oral suspensions given to young children with non-refractory acute otitis media (AOM) based on clinical endpoints and outcomes measures.

RESEARCH DESIGN AND METHODS

This was an investigator-blinded, multicenter study in which 318 children 6 months through 6 years of age with a clinical diagnosis of AOM were randomized to receive 10 days of either cefdinir (14 mg/kg divided BID) or high-dose amoxicillin/clavulanate (90/6.4 mg/kg divided BID).

MAIN OUTCOME MEASURES

Investigators evaluated clinical response at an end-of-therapy (EOT) office visit conducted on day 12-15. Outcomes of satisfaction, tolerability, and adherence were also assessed at that visit using an Otitis Parent Questionnaire.

RESULTS

The treatment groups were similar at baseline with respect to patient demographics. At the EOT visit, for cefdinir and amoxicillin/clavulanate, respectively, intent-to-treat (ITT) clinical cure rates were 82% (129/158) and 85% (134/158) (p = 0.547; 95% confidence interval [CI] -11.7 to 5.4) and per-protocol cure rates were 82% (123/150) and 90% (129/143) (p = 0.045; 95% CI -16.4 to 0.0). This difference was driven primarily by reduced cefdinir response in patients with recurrent AOM (p = 0.010) and those younger than 24 months (p = 0.039). Comparing cefdinir with amoxicillin/clavulanate, parents more often reported significantly better ease of use (89% vs. 57%; p < 0.0001), better taste (85% vs. 39%; p < 0.0001), and better adherence (at least 95% of doses) (82% vs. 61%; p < 0.0001). Diarrhea/loose stools were more common in the amoxicillin/clavulanate group than in the cefdinir group (28% vs. 18%, respectively; p = 0.0341). One patient in the cefdinir group and eight patients in the amoxicillin/clavulanate group withdrew from the study prematurely due to at least one adverse event (p = 0.0364). Study limitations included assessment of clinical recurrence by telephone call rather than office visit, exclusion of children with refractory AOM, and no assessment of middle ear microbiology.

CONCLUSIONS

Among young children with non-refractory AOM, cefdinir was as efficacious as high-dose amoxicillin/clavulanate in the ITT group, but somewhat less effective in per-protocol analysis. From the parental perspective, cefdinir was easier to administer, had a better taste, caused less diarrhea, and resulted in higher treatment adherence than high-dose amoxicillin clavulanate.

Direct detection of bacterial biofilms on the middle-ear mucosa of children with chronic otitis media

CONTEXT

Chronic otitis media (OM) is a common pediatric infectious disease. Previous studies demonstrating that metabolically active bacteria exist in culture-negative pediatric middle-ear effusions and that experimental infection with Haemophilus influenzae in the chinchilla model of otitis media results in the formation of adherent mucosal biofilms suggest that chronic OM may result from a mucosal biofilm infection.

OBJECTIVE

To test the hypothesis that chronic OM in humans is biofilm-related.

DESIGN, SETTING, AND PATIENTS

Middle-ear mucosa (MEM) biopsy specimens were obtained from 26 children (mean age, 2.5 [range, 0.5-14] years) undergoing tympanostomy tube placement for treatment of otitis media with effusion (OME) and recurrent OM and were analyzed using microbiological culture, polymerase chain reaction (PCR)-based diagnostics, direct microscopic examination, fluorescence in situ hybridization, and immunostaining. Uninfected (control) MEM specimens were obtained from 3 children and 5 adults undergoing cochlear implantation. Patients were enrolled between February 2004 and April 2005 from a single US tertiary referral otolaryngology practice.

MAIN OUTCOME MEASURES

Confocal laser scanning microscopic (CLSM) images were obtained from MEM biopsy specimens and were evaluated for biofilm morphology using generic stains and species-specific probes for H influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis. Effusions, when present, were evaluated by PCR and culture for evidence of pathogen-specific nucleic acid sequences and bacterial growth, respectively.

RESULTS

Of the 26 children undergoing tympanostomy tube placement, 13 (50%) had OME, 20 (77%) had recurrent OM, and 7 (27%) had both diagnoses; 27 of 52 (52%) of the ears had effusions, 24 of 24 effusions were PCR-positive for at least 1 OM pathogen, and 6 (22%) of 27 effusions were culture-positive for any pathogen. Mucosal biofilms were visualized by CLSM on 46 (92%) of 50 MEM specimens from children with OME and recurrent OM using generic and pathogen-specific probes. Biofilms were not observed on 8 control MEM specimens obtained from the patients undergoing cochlear implantation.

CONCLUSION

Direct detection of biofilms on MEM biopsy specimens from children with OME and recurrent OM supports the hypothesis that these chronic middle-ear disorders are biofilm-related.

Effectiveness of Centers for Disease Control and Prevention recommendations for outcomes of acute otitis media

OBJECTIVES

To determine whether we could increase adherence to the Centers for Disease Control and Prevention (CDC) recommendations with well-accepted approaches to improving quality of care and adherence to the CDC recommendations resulted in improved outcomes for acute otitis media (AOM).

METHODS

A cluster randomization study was conducted in 12 pediatric practices (6 intervention and 6 control sites). The main outcome measures were adherence to the CDC recommendations (modified to include 2 additional antimicrobial agents) and a subsequent antibiotic prescription for AOM within 30 days after diagnosis.

RESULTS

Of 3152 patients referred to research assistants, 2584 (82%) were eligible. Of those eligible, 1368 (99%) of 1382 at the intervention sites and 1138 (99%) of 1146 at the control sites consented to participate. Rates of adherence to the CDC recommendations were not significantly higher at the intervention sites than at the control sites, for initial enrollment episodes (78.2% vs 70.6%) or second episodes (62.6% vs 59.9%). After controlling for clustering according to site and covariates, children who were not treated in adherence to the CDC recommendations for both episodes had 1.60 times the odds of a subsequent prescription within 12 days, compared with those treated in adherence at both episodes.

CONCLUSIONS

Despite using evidence-based approaches that are known to influence physician behavior, we were unable to increase adherence to the CDC recommendations for treatment of AOM. However, we did establish that prescription of antimicrobial therapy consistent with the CDC recommendations for a second episode of AOM was associated with improved outcomes, measured as the need for subsequent antibiotic prescription. Because of the selection of resistant otopathogens, adherence to the CDC recommendations is likely more important in subsequent episodes of AOM than in the initial episode.

Study of nasopharyngeal bacterial flora. Second report. Variations in nasopharyngeal bacterial flora in children aged 6 years or younger when administered antimicrobial agents. Part 1

In our first report, we investigated nasopharyngeal bacterial flora related to penicillin-resistant Streptococcus pneumoniae (PRSP) and beta-lactamase-negative ampicillin-resistant Haemophilus influenzae (BLNAR) and their relation to acute upper respiratory tract infection (AURTI). This report analyzes the results of a study of nasopharyngeal bacterial flora before the administration of antimicrobial agents in 172 AURTI patients aged 6 years or younger. In addition to Gram staining, microscopic observation, and culturing, a polymerase chain reaction (PCR) method was used to identify PRSP (gPRSP) and BLNAR (gBLNAR) drug-resistant genes. Of the patients analyzed, 90% had acute otitis media (AOM) and were aged 2 years or younger. The antimicrobial agents administered were amoxicillin (34%), clavulanic acid/amoxicillin (11%), cefditren pivoxil (CDTR-PI) (43%), and others (12%). This was particularly true for patients administered CDTR-PI, among whom there were many who had already suffered one or more episodes of AOM by the age of 1 year or younger, and many in which gPRSP were detected (P < 0.01). There was a significant relation between the degree of nasopharyngeal inflammation indicated by leukocyte infiltration images and the amount of S. pneumoniae and H. influenzae detected, which are the main pathogenic bacteria causing AOM (P < 0.01). In addition to leukocyte infiltration images, there were cases in which shedding of ciliated cells was observed and/or giant monocytic cells. Both nasopharyngeal leukocyte infiltration images and/or shed cell findings observed in infant AURTI cases are important indices for the prompt detection of gPRSP and/or gBLNAR and appropriate doses of antimicrobial agents.

Study of nasopharyngeal bacterial flora. Second report. Variations in nasopharyngeal bacterial flora in children aged 6 years or younger when administered antimicrobial agents. Part 2

This report focuses on changes in the nasopharyngeal bacterial flora before and after administration of antimicrobial agents in 172 cases of acute upper respiratory infection in patients aged 6 years or younger. The antimicrobial agents administered were amoxicillin (AMPC) (34%), clavulanic acid/amoxicillin compound (11%), cefditren pivoxil (CDTR-PI) (43%), and others (12%). Changes in nasopharyngeal bacterial flora were investigated with reexaminations conducted after 2-5 days (day 2-5 subgroup), 6-10 days (day 6-10 subgroup), and 11 days and thereafter. There was a significant reduction in the Streptococcus pneumoniae detected in the group administered AMPC (AMPC group) in the day 2-5 subgroup and the day 6-10 subgroup. There was also a significant decrease in H. influenzae in the group administered CDTR-PI (CDTR-PI group) in the day 2-5 subgroup. From this it was inferred that for the most part significant changes in infectious nasopharyngeal bacteria occurred in the day 2-5 subgroups. However, a significant improvement in the degree of inflammation, as indicated by leukocyte infiltration images for the AMPC group, was observed in the day 2-5 subgroup, and for the CDTR-PI group in the day 6-10 subgroup. On the other hand, in both the antimicrobial agent groups, S. pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis were newly detected at reexamination. Furthermore, a difference in the incidence of these bacteria was observed between the 2 antimicrobial agent groups. It was suggested that such phenomena related to the survival of resistant strains or a recurrence otitis media.

A randomized, double-blind, placebo-controlled noninferiority trial of amoxicillin for clinically diagnosed acute otitis media in children 6 months to 5 years of age

OBJECTIVES

Debate continues with respect to a "watch and wait" approach versus immediate antibiotic treatment for the initial treatment of acute otitis media. In this double-blind noninferiority trial, we compared clinical improvement rates at 14 days for children (6 months to 5 years of age) with acute otitis media who were randomly assigned to receive amoxicillin or placebo.

METHODS

We enrolled healthy children who presented to clinics or the emergency department with a new episode of acute otitis media during the fall and winter months in Ottawa (from December 1999 to the end of March 2002). The children were randomly assigned to receive amoxicillin (60 mg/kg daily) or placebo for 10 days. Telephone follow-up was performed on each of days 1, 2 and 3 and once between day 10 and day 14. The primary outcome was clinical resolution of symptoms, defined as absence of receipt of an antimicrobial (other than the amoxicillin in the treatment group) at any time during the 14-day period. Secondary outcomes were the presence of pain and fever and the activity level in the first 3 days, recurrence rates, and the presence of middle ear effusion at 1 and 3 months.

RESULTS

According to clinical scoring, 415 of the 512 children who could be evaluated had moderate disease. At 14 days 84.2% of the children receiving placebo and 92.8% of those receiving amoxicillin had clinical resolution of symptoms (absolute difference -8.6%, 95% confidence interval -14.4% to -3.0%). Children who received placebo had more pain and fever in the first 2 days. There were no statistical differences in adverse events between the 2 groups, nor were there any significant differences in recurrence rates or middle ear effusion at 1 and 3 months.

INTERPRETATION

Our results did not support the hypothesis that placebo was noninferior to amoxicillin (i.e., that the 14-day cure rates among children with clinically diagnosed acute otitis media would not be substantially worse in the placebo group than the treatment group). Nevertheless, delaying treatment was associated with resolution of clinical signs and symptoms in most of the children.

Otitis media: re-evaluation of diagnosis and treatment in the era of antimicrobial resistance, pneumococcal conjugate vaccine, and evolving morbidity

The changing susceptibility of bacterial otopathogens is only one aspect of the evolving concepts regarding pathogenesis, immunoprophylaxis, pharmacodynamics, and sequelae of acute otitis media that mandates new insights for achieving a successful outcome. 2004 guidelines by the American Academy of Pediatrics for the treatment of acute otitis media provide one perspective that proposes a rethinking of the routine use of antimicrobial therapy with the hope of preventing further increases in bacterial resistance among otopathogens. The goals of this article are to incorporate the advances in diagnosis, treatment, prevention, and management of sequelae into strategies that optimize the outcome of acute otitis media and limit further emergence of resistant otopathogens.

A randomized, multicenter, double blind, double dummy trial of single dose azithromycin versus high dose amoxicillin for treatment of uncomplicated acute otitis media

BACKGROUND

High dose amoxicillin is recommended for the initial treatment of children with acute otitis media (AOM), particularly patients at risk for having drug-resistant Streptococcus pneumoniae. Single dose azithromycin (30 mg/kg) is considered an alternative agent for the treatment of AOM.

OBJECTIVE

To compare the clinical efficacy and safety of single dose azithromycin with that of high dose amoxicillin among children with uncomplicated AOM.

METHODS

This was a double blind, double dummy, multinational, clinical trial in which children (6-30 months of age) with AOM were randomized to treatment with single dose azithromycin (30 mg/kg) or high dose amoxicillin (90 mg/kg/d, in 2 divided doses) for 10 days. Tympanocentesis was performed at baseline and clinical responses were assessed at days 12-14 (end of therapy) and at days 25-28 (end of study).

RESULTS

The study enrolled 313 patients, and 83% of the patients were < or =2 years of age. A total of 158 patients in the azithromycin group and 154 in the amoxicillin group were considered clinical modified intent-to-treat patients. A middle ear pathogen was detected for 212 patients (68%). Haemophilus influenzae was the most common pathogen (isolated for 96 patients), followed by S. pneumoniae (92 patients), Moraxella catarrhalis (23 patients) and Streptococcus pyogenes (23 patients). beta-Lactamase production was observed for 17% of H. influenzae isolates and 100% of M. catarrhalis isolates. Thirty-five (38%) S. pneumoniae isolates were penicillin-nonsusceptible and 24 (26%) isolates were macrolide-resistant. At the end of therapy, clinical success rates for azithromycin and amoxicillin were comparable for all patients (84 and 84%, respectively) and for children < or =2 years of age (82 and 82%, respectively). At the end of therapy and end of study, clinical efficacies among all microbiologic modified intent-to-treat evaluable subjects were comparable for patients treated with azithromycin (80%) and patients treated with amoxicillin (83%). The rates of treatment-related adverse events for azithromycin and amoxicillin were 20% and 29%, respectively (P = 0.064). Diarrhea was more common in the amoxicillin group than in the azithromycin group (17.5 and 8.2%, respectively) (P = 0.017). Compliance, defined as completion of > or =80% of the study medication, was higher in the azithromycin group (100%) than in the amoxicillin group (90%) (P = 0.001).

CONCLUSIONS

In this study, single dose azithromycin was as effective as high dose amoxicillin for the treatment of children with AOM, whereas rates of adverse events were lower and compliance improved with the simplified single dose regimen.