Efficacy of transnasal nebulized surfactant on experimental otitis media with effusion in guinea pig

Objective

Recently experimental trials have demonstrated that nebulized natural surfactant is effective in the treatment of experimental otitis media with effusion (OME). Two methodologically incomplete studies using animal models of induced OME have reported that nebulized surfactant can improve Eustachian tube function. There have been no reports that investigated the efficacy of the nebulized surfactant for OME using analysis of tympanic membrane vibration. In this study, we evaluated the therapeutic effect of nebulized natural surfactant by investigation of tympanic membrane vibration.

Materials and methods

The guinea pigs (n = 20) were divided into three groups. Four normal guinea pigs without any treatment were used as normal controls. Sixteen pigs were given experimental OME in both ear and then divided into two groups. The OME model of guinea pig was created by transbullar injection 10 μl of lipopolysaccharide in saline. Experimental group 1 (n = 8) was nebulized phosphate buffered saline (PBS). Experimental group 2 (n = 8) was nebulized natural bovine surfactant. The transnasal nebulization was repeated for 7 days in both experimental groups. On the 8th day, both experimental groups and normal control group were measured the tympanic membrane vibration by laser Doppler vibrometer (LDV), and additionally histopathologic observation was performed by scanning electron microscope (SEM).

Results

The TM vibration velocity in nebulized PBS group showed significantly reduced mainly at low frequencies. However, nebulized natural surfactant group recovered the reduction of tympanic membrane vibration. In nebulized PBS group, SEM showed severe thickened subepithelial layer and hyperplasia of gland structure. However, in nebulized natural surfactant group, SEM showed the reduced the thickness of subepithelial layer and the loss of glandular hyperplasia.

Conclusion

From our results, the nebulized natural surfactant is postulated to be effective in the treatment of intractable OME in animal model. The measurement of tympanic membrane vibration for analysis of middle ear mechanics was significantly corresponding to the middle ear mucosal changes. LDV is a useful tool for investigate the therapeutic effect of nebulized surfactant in experimental OME. With supporting clinical studies, nebulization of natural surfactant may become noninvasive treatment of OME in future.     

Expression of HSP70 and Its Relation with Other Cytokines in Human Middle Ear Effusion

Objectives

While other cytokines are known to be associated with otitis media with effusion (OME), the involvement of heat shock protein 70 (HSP70) in middle ear effusion (MEE) is unknown. This study was undertaken to investigate the possibility of there being a HSP70 expression in human MEE and to determine its potential role as a cytokine in OME.

Methods

The levels of HSP70, tumor necrosis factor-alpha and interleukin-1beta were measured by enzyme-linked immunosorbent assay in the effusion of different groups of OME patient following collection of the MEE using our new collection system. The clinical characteristics of the OME patients and the MEE status were analyzed.

Results

HSP70 was expressed in all the types of MEE. The mucous and seromucous effusions showed higher HSP70 levels than that of the serous effusion. The HSP70 level was correlated with the levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the effusions. The positive correlations between HSP70, TNF-α and IL-1β were statistically significant (P<0.05).

Conclusion

The highly elevated level of HSP70 in the seromucous and mucous effusions implicates this protein in the chronicity of OME.     

Clinical approaches for understanding the expression levels of pattern recognition receptors in otitis media with effusion

Objectives

Bacterial infections in the normally sterile environment of the middle ear cavity usually trigger host immune response, whereby the innate immune system plays a dominant role as the host''s first line of defense. We evaluated the expression levels of Toll-like receptors (TLRs) -2, -4, -5, -9, and nucleotide-binding oligomerization domain-containing proteins (NODs) -1 and -2, all of which are related to bacterial infection in pediatric patients with otitis media with effusion (OME).

Methods

The study sample consisted of 46 pediatric patients with OME, all of whom had ventilation tubes inserted. The expression levels of TLR-2, -4, -5, -9, NOD-1 and -2 mRNA in middle ear effusion were assessed by polymerase chain reaction (PCR). Difference of pattern recognition receptors (PRRs) expression level by presence of bacteria, ventilation tube insertion rate, and effusion fluid character was assessed.

Results

All effusion fluid samples collected from patients with OME showed expression of TLR-2, -4, -5, -9, NOD-1, and -2 mRNA by PCR. However, we found no differences among expression levels of PRRs in relation to characteristics of exudates, presence of bacteria, or frequencies of ventilation tube insertion (P>0.05).

Conclusion

Our findings suggest that exudates of OME patients show PRR expressions that are related to the innate immune response regardless of the characteristics of effusion fluid, presence of bacteria in exudates, or frequency of ventilation tube insertion.     

Decreased Pattern-Recognition Receptor-Mediated Cytokine mRNA Expression in Obese Children With Otitis Media With Effusion

Objectives

To assess innate and humoral immune responses in middle ear effusion of obese pediatric patients with otitis media with effusion (OME).

Methods

We evaluated 219 children with OME, of whom 21 were obese and 198 were non-obese. We compared the expression in middle ear effusion of mRNAs encoding toll-like receptors (TLR) 2, 4, 5, and 9; nucleotide-binding oligomerization domains (NOD) 1 and 2; retinoic acid-inducible gene (RIG)-I; interleukins (IL)-6, -10, and -12; interferon (IFN)-γ; and tumor necrosis factor (TNF)-α mRNAs. We also compared the expression of immunoglobulins IgG, IgA, and IgM and the bacterial detection rate in the two groups.

Results

TLR2-mediated expression of IL-6 mRNA, TLR4-mediated expression of IL-6 and IL-10 mRNA, TLR5-mediated expression of IL-6, IL-10, and TNF-α mRNA, TLR9-mediated expression of IL-6 mRNA, and NOD2-mediated expression of IL-6, IL-12, and TNF-α mRNA were significantly lower in obese than in non-obese children (P<0.05). However, concentrations of IgG, IgA, and IgM in middle ear effusion were lower in obese than in non-obese children, but none of these differences was significant (P>0.05).

Conclusion

Mean body mass index was higher and pattern-recognition receptor-mediated cytokine mRNA expression was lower in obese than in non-obese children with OME.     

Toll-like Receptors 2 and 4 and Their Mutations in Patients with Otitis Media and Middle Ear Effusion

Objectives

Toll-like receptors (TLRs) detect microbial infections and they can directly induce innate host defense responses. TLR 2 has been shown to be primarily involved in the recognition of peptidoglycans and lipoteichoic acid of gram positive bacteria. TLR 4 recognizes lipopolysaccharides and lipoteichoic acids from both gram-negative and gram-positive bacteria. Both mutations lead a reduced capacity to elicit inflammation and they increase the risk for gram-positive and negative infections. This study was performed to investigate the expressions of TLR 2 and 4 and their mutations in patients suffering with otitis media and middle ear effusion.

Methods

Middle ear fluid samples were collected from 40 otitis media effusion (OME) patients who had ventilating tubesinserted. Bacteria in the effusion fluid were detected by standard bacterial culture. The secreted IgG, IgA and IgM were measured by Enzyme-linked immunosorbent assay. TLR 2 and 4 were assessed by performing RT-PCR. The genomic DNA from each patient was isolated from the middle ear fluid samples that were collected from 60 OME patients, and the presence of mutations was determined by performing restriction digestion and DNA sequencing analysis.

Results

Among the 40 middle ear fluid samples, bacteria were detected in 13 middle ear fluid samples. The amounts of IgM, IgA, and IgG were 151.20±60.94 ng/mL, 21.59±7.96 ng/mL and 11.55±16.98 ng/mL, respectively. TLR 2 and 4 were expressed in the middle ear fluid and the expression of TLR 2 was higher than that of TLR 4. However, there was no correlation between the expressions of TLR 2 and 4, and the concentration of immunoglobulin or the presence of bacteria (P>0.05). There ware no mutations of TLR 2 (Arg753Gln, Arg677Trp) and TLR 4 (Asp299Gly, Thr399Ile).

Conclusion

TLR 2 and 4 were expressed in all the middle ear fluid samples of OME, but the mutations of TLR 2 and 4 were not detected. TLR 2 and 4 may play a vital role in the immunological responses of patients with OME.     

Management for the Children with Otitis Media with Effusion in the Tertiary Hospital

Objectives

Recently, new evidence-based recommendations have been introduced for diagnosing and managing otitis media with effusion (OME) in children. However, there are some difficulties to follow the general guidelines in the tertiary hospitals. The purpose is to evaluate the efficiency of antibiotics or antihistamines for treatment of children with OME in the tertiary hospital with a randomized prospective clinical study.

Methods

Eighty-four children with OME who had been diagnosed in the tertiary hospital were randomized to receive 5 different medications for 2 weeks. We prescribed antibiotics (amoxicillin-clavulanate syrup) in Group I (n=16), antibiotics/steroids (prednisolone) in Group II (n=18), antibiotics/antihistamines (ebastine) in Group III (n=15), antibiotics/steroids/antihistamines in Group IV (n=17), and mucolytics (ivy leaf extract) in Group V (n=17) for control. We followed-up children every 2 weeks and evaluated the state of OME at 3 months.

Results

Thirty six (42.9%) of 84 children were resolved within average 6.9 weeks after the treatments. Thirty-six (42.9%) were treated with ventilation tube insertion and 12 patients (14.3%) were observed. There was no difference in the resolution rates of OME among the five different protocols (P>0.05). There was no difference in the resolution rates among groups who used steroids, antihistamines, steroids and antihistamines, or other medications to manage 42 children with allergies (P>0.05).

Conclusion

In the tertiary hospital, the cure rate of children with OME was not as high as well-known, and antibiotics or anti-allergic medications were not more effective than control. We may, therefore, need any other guidelines which are different from the previous evidence-based recommendations, including early operation in the tertiary hospitals.     

Concurrent assay for four bacterial species including alloiococcus otitidis in middle ear, nasopharynx and tonsils of children with otitis media with effusion: a preliminary report

Objectives

To detect the prevalences of Alloiococcus otitidis, as well as Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis in children with chronic otitis media with effusion (OME) and to simultaneously investigate the colonization of these bacteria in the nasopharynx and palatine tonsils of these patients.

Methods

The study included 34 pediatric patients with OME, and 15 controls without OME. In the study group, A. otitidis, H. influenzae, S. pneumoniae, and M. catarrhalis were investigated in the samples obtained from middle ear effusions (MEE), nasopharyngeal swabs (NPS) and tonsillar swabs (TS), using multiplex polymerase chain reaction (PCR) and conventional culture methods. Only the samples obtained from NPS and TS were studied with the same techniques in the control group.

Results

A. otitidis was isolated only in MEE and only with multiplex PCR method. A. otitidis, S. pneumoniae, M. catarrhalis, H. influenzae were identified in 35%, 8.8%, 8.8%, and 2.9%, respectively, in 34 MEE. A. otitidis was not isolated in NPS or TS of the study and the control groups.

Conclusion

The prevalence of A.otitidis is high in children with OME and A.otitidis doesn''t colonize in the nasopharynx or tonsil.     

Impact of Sulphurous Water Politzer Inhalation on Audiometric Parameters in Children with Otitis Media with Effusion

Objectives

The positive effects of spa therapy on ear, nose, and throat pathology are known but robust literature in this field, is still lacking. The aim of this study was to assess through a retrospective analysis, the effects on otitis media with effusion of Politzer endotympanic inhalation of sulphurous waters in children aged 5-9 years.

Methods

A cohort of 95 patients was treated with Politzer insufflations of sulphurous water: 58 patients did a cycle consisting of a treatment of 12 days per year for three consecutive years; 37 patients followed the same procedure for 5 years consecutively. The control population was represented by untreated, age-matched children. A standard audiometric test was used before and after each cycle of treatment.

Results

One cycle of Politzer inhalation of sulphur-rich water improved the symptoms. Three cycles definitively stabilized the improvement of hearing function.

Conclusion

Our results show that otitis media with effusion in children can be resolved by an appropriate non-pharmacological treatment of middle ear with sulphur-rich water.     

Protective effect of pulmonary surfactant on cilia of Eustachian tube in otitis media with effusion

OBJECTIVE: The aim of this study was to evaluate the effect of pulmonary surfactant (PS) on cilia of Eustachian tube (ET) in guinea pigs suffering from otitis media with effusion (OME). METHODS: A nonviable heat-killed pneumococci (HKP) solution was injected into the tympanum of guinea pig via a transtympanic approach therefore establishing models of OME (effusion in tympanum and hearing loss). After being injected with physiologic saline solution or pulmonary surfactant transtympanically, the response threshold of each guinea pig was taken by ABR. Changes of effusion and ciliary ultrastructure were observed. RESULTS: Normal group (A), the response threshold is 14.00+/-3.08 dBHL. Abundant and intact cilia were observed, ciliary morphology was normal, cilia regularly arranged in concord, no goblet cells was observed. Model-control group (B0), 5 days following the inoculation of HKP, serous effusion was present in tympanum. The response threshold is 45.00+/-5.67 dBHL. Cilia lost and arranged irregularly, hyperplasia of the goblet cells was observed. Saline group, the previously observed serous effusion of tympanum was increased or unchanged. The response threshold is 65.50+/-6.85 dBHL. Cilia were coalescing and swelling. A lot of cilia lost and arranged disorderly. A number of compound cilia of the bulging type were formed by cytoplasmic protuberances of ciliated cells. Massive mucoid secretions stuck on the surface of the ET. PS group, the previously observed serous effusion of tympanum was reduced in amount or disappeared completely. The response threshold is 23.53+/-6.32 dBHL. Ciliary morphology was generally normal. Cilia comparatively arrange in concord. A mucus deposits was adhering to the tips of cilia. CONCLUSION: The findings of the study suggest that pulmonary surfactant plays an important role in protecting of cilia of ET of guinea pigs suffering from OME.     

Decreased Expression of TLR-9 and Cytokines in the Presence of Bacteria in Patients with Otitis Media with Effusion

Objectives

Toll-like receptor (TLR)-9 recognizes unmethylated cytidine-phosphate-guanosine (CpG) motifs in bacteria. Therefore, the expression of TLR-9 may differ according to the results of bacterial culture, and thus a change in proinflammatory cytokine induction can also be expected. The authors aimed to assess the differences and relationships between the expression of TLR-9, cytokines, and nitric oxide synthase (NOS) in otitis media with effusion (OME) based on bacterial culture results.

Methods

Sixty-eight patients with OME were divided into culture-positive and culture-negative groups based on middle ear culture results. mRNA expression of TLR-9, NOS, and cytokines was measured and analyzed.

Results

Bacteria were detected in 38.2% of patients, and the distribution was as follows: coagulase negative Staphylococcus (10.3%), Staphylococcus aureus (8.8%), Streptococcus pneumonia (5.9%), and Bacillus spp. and Haemophilus influenza combined (2.9%). There were no significant differences in epidemiologic characteristics according to the culture results. Down-regulation of TLR-9 was observed in the culture-positive group (P=0.019). Cytokines including interleukin (IL)-12 (r=-0.582), tumor necrosis factor (TNF)-α (r=-0.569), interferon (IFN)-γ (r=-0.442), IL-6 (r=-0.395) and inducible NOS (r=-0.256) tended to decrease with the detection of bacteria.

Conclusion

The expression of TLR-9 significantly decreased in OME with confirmed bacterial pathogens. IL-12, TNF-α, IFN-β, IL-6 expression tended to decrease with the detection of bacteria. The presence of bacterial pathogens in OME may be related to abnormalities in the innate immune system.     

Changing Patterns of Bacterial Strains in Adults and Children With Otitis Media in Korean Tertiary Care Centers

Objectives

Otitis media (OM) is an infectious disease that affects all age brackets. Aural discharge is a typical symptom, occurring in all subtypes of OM. We have compared the identity and antibiotic sensitivity of bacteria isolated from aural discharges of adults and children with various types of OM, including acute OM (AOM), OM with effusion (OME), chronic OM (COM), and cholesteatomatous OM (CSOM).

Methods

The study involved 2,833 patients who visited five tertiary hospitals between January 2001 and December 2010 and were diagnosed with AOM, OME, COM, or CSOM. The patients were divided into a pediatric group and an adult group, and the distribution of cultured bacteria and their antibiotic sensitivity were compared in the two groups.

Results

Bacterial detection rates were higher in adults than in children with OME and COM (P=0.000 each). The majority of the bacteria cultured from patients with AOM and OME bacteria were methicillin-susceptible Staphylococcus aureus (MSSA) and Streptococcus pneumoniae. Bacteria cultured from children were more susceptible to antibiotics (P=0.002) and had higher antibiotic sensitivity (P=0.001) than were bacteria cultured from adults. The majority of bacteria culture from patients with COM and CSOM were MSSA and pathogenic Pseudomonas aeruginosa. The frequency of methicillin-resistant Staphylococcus aureus was significantly higher in adults than in children, and more strains of bacteria isolated from adults were sensitive to the antibiotics septrin, vancomycin, and teicoplanin.

Conclusion

Bacteria cultured from children were more susceptible to antibiotics and had higher antibiotic sensitivity than did bacteria cultured from adults.     

肺表面活性物质对豚鼠分泌性中耳炎的治疗作用

目的:研究肺表面活性物质(PS)对豚鼠分泌性中耳炎(OME)的治疗作用,为OME的治疗探讨新途径。方法:将50只豚鼠随机分为对照组(10只)和实验组(40只),实验组豚鼠采用灭活的肺炎链球菌(KHP)鼓室内注射,建立OME的动物模型(听力下降,中耳积液);模型建立后再将其分为造模组(20耳)、造模对照组(10耳)、治疗组(24耳,向中耳腔注射0.05mlPS)和未治组(23耳,不做任何治疗)。造模5d后,耳内镜下观察鼓膜及鼓室积液的情况,检测各组豚鼠听性脑干反应(ABR)Ⅰ、Ⅲ波潜伏期及反应阈。结果:造模组豚鼠鼓室内注射KHP悬浮液5d后,鼓室出现积液,鼓膜浑浊,光锥消失;ABR反应阈由对照组的(14.00±3.08)dB提高至(45.00±5.67)dB,其差异有统计学意义(P<0.01);治疗组鼓室内注射PS7d后,鼓室积液减少或消失,反应阈由(45.00±5.67)dB降低至(23.53±6.32)dB,分别与造模组及未治组比较,差异有统计学意义(均P<0.01);未治组鼓室积液无变化,鼓膜更加浑浊,反应阈由(45.00±5.67)dB提高至(65.50±6.85)dB。结论:PS对豚鼠OME有治疗作用。     

Skin prick test reactivity in patients with chronic eczematous external otitis

Objectives

To investigate the incidence of skin prick test (SPT) positivity in patients with eczematous external otitis.

Methods

Forty-six patients with eczematous external otitis and forty-four healthy volunteers were included in the study. All the patients were skin-tested by prick test. Reactions were assessed by the degree of redness and swelling and the size of the wheal produced.

Results

According to SPT positivity and total immunoglobulin E values, the difference between the study and the control groups was statistically significant (P<0.05). The most common skin reactions were against to mites and grasses in this study.

Conclusion

Eczematous external otitis is perhaps the most difficult to treat of all forms of external otitis because the provocative agents usually remain undiagnosed. Patients suffering from eczematous external otitis symptoms should be investigated for allergens and be informed for prevention of the causative agents. SPT might be performed in cases of prolonged or treatment-resistant external otitis.     

Role of immunoglobulin E and gastro-esophageal reflux disease in the development of otitis media with effusion

Introduction

The role of allergy in chronic otitis media with effusion (OME) is controversial. Aim of the work: To study the role of allergy and gastroesphogeal reflux diseases in the etiology of OME. Materials and methods: It is a prospective study that was done on 43 cases; 30 patients suffer from OME with mean age 6.8 years and 13 control child with mean age 8.3 years. Blood sample were taken from patients and control children for assay of total Immunoglobulin E (IgE) and serum pepsinogen 1 (PG1). Effusion fluid samples were taken from middle ear of the patients during myringotomy and ventilation tube insertion; IgE and PG1 were assayed in the effusion samples. Total IgE and PG1 were assayed by enzyme-linked immunosorbent assay.

Results

Our results showed that, there is a correlation between serum IgE and Effusion IgE in the patients group, there is a significant negative correlation between PG1 in the effusion and serum of the studied patients.

Conclusion

Allergy is a possible risk factor for the development of OME. The level of PG1in the effusion is one tenth of its level in the serum of the patients.     

Dendritic cells and lymphocyte subpopulations of the adenoid in the pathogenesis of otitis media with effusion

Objective

To assess dendritic cells and lymphocyte subpopulations of adenoid and peripheral blood in patients with adenoid hypertrophy and otitis media with effusion (OME). To explain the influence of immunological status of adenoid on the development of OME.

Methods

The examined group covered 123 surgically treated patients due to adenoid hypertrophy (39 children with coexisting OME). Preoperative clinical examination included anamnesis and otorhinolaryngological examination with nasofiberoscopy, videootoscopy and assessment of the hearing organ. The material of the study were surgically removed adenoids and peripheral blood samples prepared and then analyzed by the means of tri-colour flow cytometry. The obtained results were statistically analyzed.

Results

Significant differences between patients with adenoid hypertrophy with coexisting OME and children without OME concerning CD19+CD69+, CD3+CD69+, CD4+CD69+CD8+CD69+ and CD19+CD25+ cells were observed. No statistical differences were revealed in the blood of patients with and without OME. Several statistical differences were noted between the adenoid and peripheral blood in patients with otitis media with effusion concerning BDCA-2+/CD123+ cells, CD3+ and CD19+ lymphocytes with the markers of their activation.

Conclusions

The adenoid is involved in local immune response regardless of constitutional immunological mechanisms in patients with OME coexisting with adenoid hypertrophy. Significantly lower percentage of CD3+CD69+, CD4+CD69+, CD8+CD69+ and CD19+CD69+ cells of adenoid in patients with OME attests to reduced T-cells activation of the adenoid in relation to patients without OME.     

Is Carhart notch an accurate predictor of otitis media with effusion?

Background

In the era of pediatric otolaryngology, a number of different methods have been used for the diagnosis of otitis media with effusion (OME). Although there are divers articles within the filed of assessment of the accuracy of diagnostic methods of OME, surprisingly there are very few data published and a small number of researches explaining the accuracy of Carhart notch (CN) for diagnosis of OME cases and comparing the CN with abnormal tympanic membrane findings in binocular microtympanoscopy.

Methods

Audiometric parameters studied in 89 children (178 ears) suffering from chronic otitis media with effusion. Significant CN was defined as a minimum depression of 10 dB in comparison of the rest of thresholds, at any frequency from 500 to 4000 Hz. Intra-operative microscopic otoscopic findings and the type of middle ear fluid were documented in a specially formatted questionnaire.

Results

The incidence of CN was 44.94% (80 ears) and that of significant CN was 25.28% (45 ears). The correlation between abnormal tympanic membrane findings and significant CN was significant and the association between CN and middle ear effusion (MEE) was not statistically significant.

Conclusions

Significant CN is a sensitive diagnostic tool for detection of MEE but not specific. The diagnosis of OME in children requires a combinational diagnostic methods including tympanometry and audiometric variables especially CN.     

Clinical evaluation of pepsin for laryngopharyngeal reflux in children with otitis media with effusion

Objective

We sought to evaluate the clinical role of pepsin for laryngopharyngeal reflux (LPR) in children with otitis media with effusion (OME).

Methods

Pepsin/pepsinogen and fibrinogen were analyzed in fifty effusion and blood samples of children with OME using enzyme linked immunosorbent assay (ELISA). Ambulatory 24-h dual-probe pH monitoring was additionally performed in 31 children divided into two groups according to response of medical treatment.

Results

The effusion levels of pepsin/pepsinogen ranged from 8.5 to 1512 μg/dl and were up to 4–540 times higher than the concentrations found in plasma samples. The effusion levels of fibrinogen ranged from 0.05 to 4.1 g/dl. Some effusion samples showed fibrinogen concentrations did not exceed 10 times higher than the concentrations found in plasma samples and others showed lower concentrations. The pH of effusion samples was 7.13 to 8.72. Dual-probe pH monitoring showed that 22/31 (71%) of the studied children had significant acid reflux documented by either the esophageal probe or the pharyngeal probe and all of them had LPR. There is a significant positive correlation between the level of pepsin assayed in the effusions and the number of pharyngeal reflux episodes measured by pH monitoring.

Conclusions

Analysis of pepsin/pepsinogen in effusion samples of children with OME, using ELISA, can be considered as a reliable biochemical marker for assessment of laryngopharyngeal reflux.     

Histo-morphological changes of eustachian tube of guinea pigs with effusion after being treated by pulmonary surfactant]

OBJECTIVE: To study the effect of pulmonary surfactant on otitis media with effusion in guinea pigs to find a new way to manage otitis media with effusion. METHODS: Nonviable heat-killed pneumococci (HKP) solution was inoculated into the middle ear cavity in guinea pigs via a transeardrum approach to set up a model of otitis media with effusion in guinea pigs. Seven days after being injected with pulmonary surfactant (PS) by transeardrum approach, ABR threshold and histomorphological changes of eustachian tube mucosa of guinea pigs were examined by light microscopy and scanning microscopy. RESULTS: Five days following inoculation of HKB serous effusion were present in the middle ear cavity of guinea pigs, but disappearance of light cone. Response (mean +/- s) threshold raised from (14.0 +/- 3.1) dB to (45.0 +/- 5.7) dB. The eustachian tube mucosa was thickened and lined eosin-stained structureless matter over mucosa, while cilia of eustachian tube mucosa irregularly arranged. Seven days after being treated by PS, serous effusion of tympanum was reduced or disappeared, and response threshold decreased from (45.0 +/- 5.7) dB to (23.5 +/- 6.3) dB. There was significantly difference between them (P < 0.001). Eustachian tube mucosa was thinned, Cilia of eustachian tube mucosa regularly arranged to the nasopharynx. CONCLUSION: Pulmonary surfactant plays a important role in otitis media with effusion of guinea pigs.