Otitis media: an update on current pharmacotherapy and future perspectives

Resolution of otitis media in a humanized mouse model

Otitis media (OM) is one of the largest public health problems of children and has devastating impacts in developing countries. The substantial medical and human costs involved have led to research to understand the disease and improve treatment. Animal models of OM have yielded critical information about the immune, inflammatory and genetic mechanisms of OM. However, it is important to link animal studies to human immune and inflammatory responses. In recent years, "humanized" mice have become a valuable tool to study the human immune system in an animal model. Here we describe the first use of humanized mice to study OM. We demonstrate that humanized mice with a sufficient degree of engraftment recapitulate a normal middle ear (ME) inflammatory response to bacterial infection, including the recruitment of human immune cells, and exhibit normal recovery. Moreover, these animals exhibit regulated expression of human-specific immune and inflammatory genes in the ME. In contrast, mice with insufficient engraftment fail to resolve OM. This model has many potential uses in OM research, including using hematopoietic stem cells from patients with differing degrees of OM susceptibility, to understand the role of human immune responses in proneness to this common childhood disease.

Lack of the hyaluronan receptor CD44 affects the course of bacterial otitis media and reduces leukocyte recruitment to the middle ear

BACKGROUND

CD44 is a multifunctional molecule that plays major roles in both leukocyte recruitment and tissue proliferation. Since mucosal hyperplasia and leukocyte infiltration of the middle ear cavity are major features of otitis media, we evaluated the role of CD44 in the pathophysiology and course of this disease in a mouse model of middle ear infection. Expression of genes related to CD44 function were evaluated using gene arrays in wild-type mice. The middle ears of mice deficient in CD44 were inoculated with non-typeable Haemophilus influenzae. Histopathology and bacterial clearance were compared to that seen in wild-type controls.

RESULTS

We observed strong up-regulation of CD44 and of genes related to its role in leukocyte extravasation into the middle ear, during the course of acute otitis media. Mice deficient in CD44 exhibited reduced early mucosal hyperplasia and leukocyte recruitment, followed by delayed resolution of infection and persistent inflammation.

CONCLUSIONS

CD44 plays an important role in OM pathogenesis by altering the mucosal growth and neutrophil enlistment. Targeted therapies based on CD44 could be useful adjuncts to the treatment of middle ear infections.

Topical otic drugs in a multi-purpose manufacturing facility: a guide on determination and application of permitted daily exposure (PDE)

Due to newly introduced EU GMP (Good Manufacturing Practice) guideline for Medicinal Products for Human and Veterinary use, product specific permitted daily exposure (PDE) for toxicological evaluation in multi-purpose facilities are required within a documented process for risk assessment. European Medicines Agency (EMA) guidance on setting PDE limits so far focused on systemic administration routes such as intravenous (IV), oral or inhalation. This article provides guidance on setting PDE values for risk management purposes in multi-purpose facilities for active pharmaceutical ingredients (APIs) applied as topical otic drugs to the outer ear canal. The therewith determined PDE otic, is used for the calculation of maximum safe carry-over (MSC) in manufacturing scenarios where a topical otic product is manufactured followed by another topical otic product.

Innate Immunity: Orchestrating Inflammation and Resolution of Otitis Media

Otitis media (OM) is a common disease in young children, accounting for more office visits and surgeries than any other pediatric condition. It is associated with an estimated cost of five billion dollars annually in the USA. Moreover, chronic and recurrent middle ear (ME) disease leads to hearing loss during critical periods of language acquisition and learning leading to delays in reaching developmental milestones and risking permanent damage to the ME and inner ear in severe cases. Therefore, research to understand the disease pathogenesis and identify new therapeutics is important. Although OM is a multifactorial disease, targeting the molecular mechanisms that drive inflammation and OM resolution is critical. In this review, we discuss the current evidence suggesting that innate immune receptors and effectors play key roles in OM by mediating both the ME inflammatory responses and recovery.

Discovery of a Biological Mechanism of Active Transport through the Tympanic Membrane to the Middle Ear

Otitis media (OM) is a common pediatric disease for which systemic antibiotics are often prescribed. While local treatment would avoid the systemic treatment side-effects, the tympanic membrane (TM) represents an impenetrable barrier unless surgically breached. We hypothesized that the TM might harbor innate biological mechanisms that could mediate trans-TM transport. We used two M13-bacteriophage display biopanning strategies to search for mediators of trans-TM transport. First, aliquots of linear phage library displaying 10^10th 12mer peptides were applied on the TM of rats with active bacterial OM. The middle ear (ME) contents were then harvested, amplified and the preparation re-applied for additional rounds. Second, the same naïve library was sequentially screened for phage exhibiting TM binding, internalization and then transit. Results revealed a novel set of peptides that transit across the TM to the ME in a time and temperature dependent manner. The peptides with highest transport capacities shared sequence similarities. Historically, the TM was viewed as an impermeable barrier. However, our studies reveal that it is possible to translocate peptide-linked small particles across the TM. This is the first comprehensive biopanning for the isolation of TM transiting peptidic ligands. The identified mechanism offers a new drug delivery platform into the ME.

Antibiotic resistance of Streptococcus pneumoniae in children with acute otitis media treatment failure

OBJECTIVES

The emergence of antibiotic-resistant bacteria is a major cause of treatment failure in children with acute otitis media (AOM). This study aimed to analyze the types of bacterial strains in fluid isolated from the middle ear of children with AOM who did not respond to oral antibiotic treatment. We also determined the antibiotic resistance of the most frequently isolated bacterial strain (Streptococcus pneumoniae) found in these children.

METHODS

This was a prospective study of 157 children with AOM aged from 6 months to 7 years admitted due to unsuccessful oral antibiotic treatment. All children underwent a myringotomy, and samples of the middle ear fluid were collected for bacteriological examination.

RESULTS

Positive bacterial cultures were obtained in 104 patients (66.2%), with Streptococcus pneumoniae (39.69%), Haemophilus influenzae (16.03%) Staphylococcus aureus (16.03%), Staphylococcus haemolyticus (6.9%) and Streptococcus pyogenes (5.34%) found most frequently. The majority (65.4%) of S. pneumoniae strains were penicillin-intermediate-resistant or penicillin-resistant, and 67.2% strains of S. pneumoniae were multidrug-resistant.

CONCLUSIONS

We identified S. pneumoniae as the most frequently isolated pathogen from the middle ear in children with AOM treatment failure and determined that the majority of strains were antibiotic-resistant. We propose that the microbiological identification of bacterial strains and their degree of antibiotic resistance should be performed prior to therapy in order to choose the most appropriate antibiotic therapy for children with AOM treatment failure.

Parental views on acute otitis media (AOM) and its therapy in children--results of an exploratory survey in German childcare facilities

Background

Acute otitis media (AOM) is one of the main reasons for medical consultation and antibiotic use during childhood. Although 80 % of AOM cases are self-limiting, antibiotic prescription is still high, either for physician- or for parent-related factors. This study aims to identify parental knowledge about, beliefs and attitudes towards, and experiences with AOM and its therapy and thus to gain insights into parents’ perspectives within the German health care system.

Methods

An exploratory survey was conducted among German-speaking parents of children aged 2 to 7 years who sent their children to a childcare facility. Childcare facilities were recruited by convenience sampling in different urban and rural sites in Germany, and all parents with children at those facilities were invited to participate. Data were evaluated using descriptive statistical analyses.

Results

One-hundred-thirty-eight parents participated. Of those, 75.4 % (n = 104) were AOM-experienced and 75.4 % (n = 104) had two or more children. Sixty-six percent generally agree that bacteria cause AOM. 20.2 % generally agree that viruses cause AOM. 30.5 % do not generally agree that viruses cause AOM. Eight percent generally agree that AOM resolves spontaneously, whereas 53.6 % do not generally agree. 92.5 % generally (45.7 %) and partly (42.8 %) agree that AOM needs antibiotic treatment. With respect to antibiotic effects, 56.6 % generally agree that antibiotics rapidly relieve earache. 60.1 % generally agree that antibiotics affect the gastrointestinal tract and 77.5 % generally agree that antibiotics possibly become ineffective after frequent use. About 40 % generally support and about 40 % generally reject a “wait-and-see” strategy for AOM treatment. Parental-reported experiences reveal that antibiotics are by far more often prescribed (70.2 %) than actively requested by parents (26.9 %).

Conclusions

Parental views on AOM, its therapy, and antibiotic effects reveal uncertainties especially with respect to causes, the natural course of the disease and antibiotic effects on AOM. These results indicate that more evidence-based information is needed if parents’ health literacy in the treatment of children with AOM is to be enhanced. The discrepancy between reported parental requests for antibiotics and reported actual prescriptions contradicts the hypothesis of high parental influence on antibiotic use in AOM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0516-3) contains supplementary material, which is available to authorized users.