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Importance: The adenoid pad has long been considered a reservoir for bacteria in the pathogenesis of otitis media with effusion (OME). However, bacteria more reminiscent of external auditory canal (EAC) commensals are often demonstrated within middle ear aspirates., Objective: To compare the microbiota of the EAC, the middle ear with OME, and the adenoid pad to further clarify the true source of middle ear bacteria., Design, Setting, and Participants: Middle ear fluid (MEF) aspirates and EAC lavages were collected from 18 children with OME undergoing ventilation tube insertion from June 1, 2014, to August 31, 2015, at Women and Children's Hospital, Adelaide, Australia. Adenoid pad and MEF samples were included from a previous study. Samples were analyzed using sequencing of the 16S ribosomal RNA gene. Previously collected microbiota data from the adenoid pad were collated for analysis., Main Outcome Measures: Mean relative abundance of top bacterial genera for the MEF, EAC, and adenoid pad samples., Results: Eighteen pediatric patients with chronic OME (6 female; 12 male; mean [SD] age, 48 [36] months) were recruited prospectively, with 34 paired MEF and EAC samples. The MEF microbiota (mean relative abundance [SD]) consisted of Alloiococcus otitidis (37.5% [40.0%]), Haemophilus (14.4% [29.1%]), Moraxella (10.0% [26.4%]), Staphylococcus (8.2% [21.9%]), and Streptococcus (3.8% [13.1%]). The mean relative abundance (SD) microbiota of the EAC demonstrated a sparsity of classic otopathogens, including Haemophilus (0.3% [0.8%]), Moraxella (0.3% [0.7%]), and Streptococcus (0.2% [0.6%]), but had a high abundance of Alloiococcus (58.0% [44.1%]), Staphylococcus (20.8% [34.0%]), and Pseudomonas (3.2% [17.1%]). In contrast, based on previously collected data, the microbiota of the adenoid pad showed a high abundance of the classic otopathogens with a sparsity of EAC genera for Alloiococcus (0.1% vs 28.9%, respectively; P < .001), Haemophilus (25.2% vs 18.2%, respectively; P = .002), Staphylococcus (0.2% vs 10.8%, respectively; P = .02), Streptococcus (12.7% vs 4.2%, respectively; P < .001), and Pseudomonas (0 vs 2.1% respectively; P < .001). The microbiota of the MEF collected during 2 consecutive years were similar (Alloiococcus, 22.7% vs 37.5%; Haemophilus, 22.5% vs 14.0%; Staphylococcus, 10.9% vs 10.7%; Moraxella, 5.0% vs 9.7%; Corynebacteria, 6.2% vs 3.1%; Streptococcus, 4.8% vs 3.7%; and Pseudomonas, 1.1% vs 3.0%; P ≥ .05)., Conclusions and Relevance: The EAC and the nasopharynx could serve as reservoirs for microbiota of the middle ear. Furthermore, the microbiota of the middle ear with effusion appear to be relatively stable over time and between populations with OME.

Importance: Understanding how pneumococcal proteins affect the pathology of the middle ear and inner ear is important for the development of new approaches to prevent otitis media and its complications., Objectives: To determine the viability and virulence of Streptococcus pneumoniae mutants deficient in pneumolysin (Ply-) and pneumococcal surface protein A (PspA-) in the chinchilla middle ear., Design: Bullae of chinchillas were inoculated bilaterally with wild-type (Wt), Ply-, PspA-, and Ply-/PspA- strains. Bacterial colony-forming units (CFUs) in middle ear effusions were counted at 48 hours. The CFUs of the PspA- group were also counted at 6 to 36 hours after inoculation. Temporal bone histopathological results were compared., Setting and Participants: Twenty-seven chinchillas in an academic research laboratory., Exposure: Chinchilla middle ears were inoculated with S pneumoniae to produce sufficient volumes of effusions and noticeable histopathological changes in the ears., Main Outcomes and Measures: The CFU counts in the middle ear effusions and histopathological changes were compared to determine the effect of pneumococcal protein mutations on chinchilla ears., Results: At 48 hours, CFUs in middle ears were increased for the Wt and Ply-/PspA- strains, but Ply- remained near inoculum level. No bacteria were detected in the PspA- group. The CFUs of PspA- decreased over time to a low level at 30 to 36 hours. In vitro, PspA- in Todd-Hewitt broth showed an increase in bacterial growth of 2 logs at 43 hours, indicating PspA- susceptibility to host defenses in vivo. The PspA- and Ply- groups had fewer pathologic findings than the Wt or Ply-/PspA- groups. Histopathological analysis showed significant differences in the number of bacteria in the scala tympani in the Wt group compared with the Ply-, PspA-, and Ply-/PspA- groups. The PspA- strain was the least virulent., Conclusions and Relevance: The PspA- mutant was much less viable and less virulent in the ear than the Wt, Ply-, and Ply-/PspA- strains. There was no significant attenuation in the viability and virulence of the Ply-/PspA- mutant compared with the Wt or single mutants. The viability and virulence of pneumococcal mutants seemed to be protein and organ specific.

Objectives: To examine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization among children undergoing bilateral myringotomy and tube insertion with or without adenoidectomy for chronic otitis media with effusion or recurrent acute otitis media, as well as to examine the occurrence of postoperative otorrhea in children who have vs do not have MRSA colonization., Design: Prospective cohort study., Setting: Hospital-based pediatric otolaryngology practice in a metropolitan area., Patients: Seventy-six children (51 boys and 25 girls), with a mean (SD) age of 3.6 (1.8) years., Interventions: Cultures for S aureus from the nasopharynx, external auditory canals, middle ears, and adenoid were obtained at the time of surgery, as well as middle ear cultures for bacteriologic culture and sensitivity. Patients were followed up for the development of otorrhea., Main Outcome Measures: Prevalence of MRSA colonization and predictors of subsequent otorrhea., Results: The prevalence of S aureus colonization at the time of bilateral myringotomy and tube insertion was 7.9% (95% CI, 3.0%-16.4%), and the prevalence of MRSA colonization was 3.9% (95% CI, 0.8%-11.1%). All MRSA-positive specimens were resistant to erythromycin, and 2 were resistant to clindamycin. The mean (SD) follow-up period was 11.6 (3.6) months. Twenty-seven patients (35.5% [95% CI, 25.1%-46.9%]) developed at least 1 episode of otorrhea. One of 3 patients with MRSA colonization had subsequent otorrhea. The only predictor of otorrhea was younger age., Conclusions: The prevalence of MRSA colonization among otitis-prone children was similar to rates reported among the general pediatric community. Methicillin-resistant S aureus colonization at the time of bilateral myringotomy and tube insertion was not predictive of subsequent otorrhea.

Objective: To characterize bacterial microbiota in middle ear, adenoid, and tonsil specimens using 16SrRNA gene-based pyrosequencing analysis., Design: Cross-sectional study of bacterial microbiota in middle ear, adenoid, and tonsil specimens from a pediatric patient with chronic serous otitis media. Middle ear, adenoid, and tonsil specimens from a pediatric patient were collected and underwent cell lysis and DNA isolation. Pyrosequencing was performed on the 454 Life Sciences GS FLX platform (Roche Diagnostics Corp, Branford, Connecticut). Pyrosequencing data were processed, quality-checked, and taxonomically classified to generate an abundance-based matrix. Ecological analyses were performed., Setting: Academic, tertiary referral center., Main Outcome Measures: Comparative microbiome analysis., Results: We detected a total of 17 unique bacterial families, with 9, 9, and 12 bacterial families from the middle ear, tonsil, and adenoid specimens, respectively. Pseudomonadaceae dominated the middle ear microbiota at 82.7% relative abundance, whereas Streptococcaceae dominated the tonsil microbiota at 69.2%. Multiple bacteria, including Pseudomonadaceae, Streptococcaceae, Fusobacteriaceae, and Pasteurellaceae, dominated the adenoid microbiota. Overlap between the middle ear and the tonsil microbiota was minimal. In contrast, the adenoid microbiota encompassed bacteria detected from middle ear and tonsil., Conclusions: Bacterial community analysis using pyrosequencing analysis revealed diverse, previously unknown bacterial communities in a set of pediatric middle ear, tonsil, and adenoid specimens. Our findings suggest that the adenoid may be a source site for both the middle ear and tonsil microbiota. An ecological framework is appropriate in comparative analysis of microbiota from nonsterile body sites.

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.

Objectives: To determine the optimal approach for nasopharyngeal culture and to establish which approach children tolerate best., Design: Cross-sectional study., Setting: A pediatric otolaryngology department of a Dutch tertiary care hospital., Patients: A cohort of 42 children with chronic suppurative otitis media., Intervention: Paired nasopharyngeal samples were collected transorally and transnasally and cultured for potential aerobic pathogens., Main Outcome Measures: The isolation rate of both samples and the amount of discomfort measured by the visual analog scale., Results: Forty-six (87%) of 53 samples obtained transnasally were culture positive vs 40 (75%) of 53 samples obtained transorally (P = .20). Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus were found more frequently with the transnasal than with the transoral approach: 34% vs 13% (P = .003), 62% vs 51% (P = .20), 30% vs 19% (P = .15), and 21% vs 11% (P = .18), respectively. Mean (SD) visual analog scale scores were 5.3 (1.0) and 3.4 (1.7) (P<.001) for the transnasal and transoral approaches, respectively., Conclusions: Although the transoral approach is better tolerated in children, the isolation rate of the transnasal approach is higher, especially for S. pneumoniae. The transnasal sampling technique should therefore be the preferred approach for detection of potential pathogens in the nasopharynx in children.

Objective: To correlate the aerobic and anaerobic microbiologic findings of concurrent chronic otitis media with effusion and chronic maxillary sinusitis., Methods: Cultures were obtained from 32 children with concurrent chronic otitis media with effusion and maxillary sinusitis who underwent tympanostomy tube placement., Results: A total of 42 isolates, 24 aerobic and 18 anaerobic, were recovered from 30 patients; 27 were isolated from both sites, 4 from the ear only, and 11 from the sinus only. The most common isolates were Haemophilus influenzae (9 isolates), Streptococcus pneumoniae (n = 7), Prevotella species (n = 8), and Peptostreptococcus species (n = 6). Microbiological concordance between the ear and sinus was found in 22 (69%) of culture-positive patients., Conclusion: The concordance in recovery of organisms in more than two thirds of the patients illustrates the common bacterial etiology between chronic otitis media with effusion and chronic sinusitis in children.

Context: Otitis media with effusion (OME) can lead to significant hearing loss in children. Although previous studies have shown that bacterial DNA is present in a significant percentage of effusions sterile by culture, whether the DNA represents viable organisms or "fossilized remains" is unknown., Objective: To determine if bacterial messenger RNA (mRNA), as detected by a reverse transcriptase-polymerase chain reaction (RT-PCR)-based assay, is present in chronic pediatric middle ear effusions that contain bacterial DNA but are sterile by standard cultural methods. Bacterial mRNAs have a half-life measured in seconds to minutes; therefore, detection of bacteria-specific mRNAs would be evidence that metabolically active organisms are present., Design: Blinded comparative study., Patients: A total of 93 effusions from pediatric outpatients seen for myringotomy and tube placement for chronic (>3 months) OME (median age of children, 17 months)., Setting: Tertiary care pediatric hospital., Main Outcome Measures: Percentage of positive test results for RT-PCR-based assays compared with culture for Haemophilus influenzae and concordance between RT-PCR and PCR-based findings for bacterial nucleic acids., Results: Eleven (11.8%) of the 93 specimens tested positive by culture, PCR, and RT-PCR for H influenzae. A total of 29 specimens (31.2%) were positive by PCR but negative by culture for H influenzae. All 29 specimens were positive by RT-PCR for H influenzae-specific mRNA., Conclusions: The RT-PCR-based assay system can detect the presence of bacterial mRNA in a significant percentage of culturally sterile middle ear effusions, establishing the presence of viable, metabolically active, intact organisms in some culture-negative OME.

Objective: To elucidate the role of cytokines, immunoglobulins, and bacterial pathogens in the middle ear effusions (MEEs) of children with otitis media (OM)., Design: Paired MEEs and serum samples collected from consecutive patients were assayed for immunoglobulins. Middle ear effusions were cultured for bacterial pathogens and assayed for interleukin-1 beta, interleukin-6, tumor necrosis factor alpha, and interferon gamma. The medical charts of the patients were retrospectively reviewed to define the history of OM., Subjects: Seventy-five patients with a history of recurrent acute OM, persistent OM with effusion, or both. Exclusion criteria included the presence of a major coexisting condition, or an unclear or atypical history of OM., Setting: A private practice at a tertiary care children's hospital., Interventions: At the time of tympanostomy tube placement, with the patient under general anesthesia, one MEE and a serum sample were collected., Results: Interleukin-1 beta was detected in 58% (44/75) MEEs; interleukin-6, 83% (60/72); tumor necrosis factor alpha, 37% (28/75) [corrected]; and interferon gamma, 61% (45/74). Concentrations of interleukin-1 beta, interleukin-6 and tumor necrosis factor alpha in MEEs were highly correlated with each other (P < .01 for each association) suggesting increased local production and the expected effects of cytokines stimulating their own production during OM. High concentrations of tumor necrosis factor alpha in MEEs were also associated with a history of multiple placements of tympanostomy tubes (r = .63)., Conclusions: These data suggest a regulatory role for cytokines in inflammation during OM, and suggest that high concentrations of tumor necrosis factor alpha in MEEs may be a marker for OM chronicity.

Objective: To determine if the polymerase chain reaction (PCR) can detect bacterial DNA in pediatric middle ear effusions that are sterile by standard cultural methods., Design: Single-center, blinded, comparative study of diagnostic assays. The PCR-based detection systems for Moraxella catarrhalis, Haemophilus influenzae, and Streptococcus pneumoniae were designed and validated using a battery of DNAs obtained from cultured bacteria. Chronic middle ear effusion specimens were collected and comparatively analyzed by culture and the PCR., Setting: Tertiary care pediatric hospital., Patients: A total of 97 middle ear effusions were collected from pediatric outpatients at Children's Hospital of Pittsburgh (Pa) during myringotomy and tube placement for chronic otitis media with effusion (duration > 3 months). All patients had failed multiple courses of antimicrobial therapy and were diagnosed by a combination of validated otoscopy and tympanograms., Main Outcome Measure: Differences in the percentage of positive test results between PCR-based assays and culture for M catarrhalis, H influenzae, and S pneumoniae., Results: Of the 97 specimens of otitis media with effusion, 28 (28.9%) tested positive by both culture and PCR for M catarrhalis, H influenzae, or S pneumoniae. An additional 47 specimens (48%) were PCR positive/culture negative for these three bacterial species. Thus, 75 (77.3%) of the 97 specimens tested PCR positive for one or more of the three test organisms. The minimum number of bacterial genomic equivalents present in the average culture-negative ear was estimated to be greater than 10(4) based on dilutional experiments., Conclusions: The PCR-based assay systems can detect the presence of bacterial DNA in a significant percentage of culturally sterile middle ear effusions. While this finding is not proof of an active bacterial infectious process, the large number of bacterial genomic equivalents present in the ears is suggestive of an active process.

Neonatal otitis media may be an isolated infection or part of a more complex sepsis syndrome. Because early studies suggested that the microbiologic characteristics of neonatal otitis media included a high risk of gram-negative coliforms and Staphylococcus aureus, tympanocentesis was recommended routinely. Subsequent studies have supported empiric medical therapy in selected patients, reserving tympanocentesis for patients in whom medical treatment fails. Because of these conflicting recommendations, records from 37 neonates with otitis media who underwent tympanocentesis from 1986 through 1991 were studied retrospectively. Cultures in one outpatient (11%) and four inpatients (13%) yielded Escherichia coli, all of which were sensitive to amoxicillin. No cultures of S aureus were identified. Sterile cultures and pneumococcus isolates were found most frequently. No septic or intracranial complications were noted. All patients were discharged on regimens of routine antibiotics for otitis media.

We reviewed the reported experience with actinomycosis otomastoiditis in the international literature, along with a recent case from our experience. All recently reported cases presented with persistent drainage and partial response to multiple courses of antibiotics. Diagnosis was uniformly made postoperatively, and the outcome was excellent following a prolonged course of antibiotic treatment.

This controlled prospective study was designed to identify predictors for postoperative otorrhea among 157 children with chronic otitis media with effusion undergoing myringotomy and tympanostomy tube placement (intubation). Ear canal disinfection with 70% alcohol or povidone-iodine did not significantly alter ear canal or middle ear effusion bacteriology, or the frequency of otorrhea during the first 7 days after surgery. However, the risk of otorrhea on the second postoperative day was significantly increased by the presence of a bacterial pathogen in the ear canal (relative risk, 2.4), or in the middle ear effusion (relative risk, 1.9), and the presence of inflamed middle ear mucosa at surgery (relative risk, 1.7) after controlling for age, preoperative antibiotics, and postoperative ototopical cortisporin treatment. The use of systemic antimicrobial treatment in children with inflamed middle ear mucosa at surgery or whose ear canal or middle ear effusion cultures are positive for bacterial pathogens might reduce the incidence of post-operative otorrhea in children undergoing intubation for chronic otitis media with effusion.

There is concern that third-generation cephalosporins may not be effective in the treatment of acute otitis media due to Streptococcus pneumoniae. Using the chinchilla animal model, we compared two third-generation cephalosporins, cefixime (Suprax) and ceftibuten (investigational), with ampicillin and saline controls in an investigator-blinded, randomized trial. Whereas the saline controls performed worse than all other groups, no significant differences were detected among the three antibiotics regarding the time required to sterilize the middle ear cleft, or the prevalence of positive cultures after 10 days of therapy. The statistical power of the comparisons of cefixime and ceftibuten with ampicillin were 98% and 67%, respectively. The results of this in vivo animal study fail to support the contention that the two third-generation cephalosporins investigated are not effective in the treatment of pneumococcal acute otitis media. Caution is advised when extrapolating these results to the general clinical setting.

Pathologic changes (sensorineural hearing loss, labyrinthitis, meningitis) can follow otitis media. Various macromolecular substances demonstrably enter the inner ear via the round window membrane, but its permeability to bacteria is less known. We inoculated Streptococcus pneumoniae type 7F bilaterally into the middle ears of two groups of chinchillas, with and without grafted round window membranes. Inner ears of inoculated animals were observed by light and electron microscopy. None with continuous grafts had labyrinthitis. Bacteria penetrated all three layers of nongrafted round window membranes and into all cochlear turns, entering Schuknecht's channels and following neuronal pathways; nerves were often degenerated, hair cells were damaged or missing, and the stria vascularis was edematous and hemorrhagic. The neural damage suggests a mechanism for the hearing loss that can follow otitis media. Absence of labyrinthitis and meningitis in grafted animals suggests a tympanogenic pathway for the bacteria.

Adherence of nontypable Haemophilus influenzae and Streptococcus pneumoniae to nasopharyngeal epithelial cells was investigated in vitro. Both strains had higher affinity to the epithelial cells of children than to those of adults. In children, the adherence was significantly greater in patients with otitis media with effusion than in normal subjects. Secretory IgA in nasopharyngeal secretions was found to have antibody activity against the bacteria. Adherence of both bacteria was significantly smaller in the group having secretory IgA antibody activity than in the group having no activity. These results suggest that bacterial adherence to the nasopharynx may play an important role in the pathogenesis of otitis media with effusion in children, and that secretory IgA in nasopharyngeal secretions may be related to the decrease of adherence.

Cultures of middle ear fluids (MEFs) are needed to determine both efficacy of antibiotics and vaccines, and microbiologic outcome of otitis media (OM). We reviewed data on 221 children, aged 2 months to 12 years; 122 had acute otitis media (AOM), 99 had asymptomatic MEF. We included only Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis, and Staphylococcus aureus as pathogens. Of children with AOM, MEF was sterile or contained nonpathogens in both ears in 51, and one or more pathogens in 71. Of these 71, 40 had the same pathogen or pathogens in both ears; 25 patients had a pathogen in one ear and sterile fluid or only nonpathogens in the other; four patients had a different pathogen in each ear; and two patients had two pathogens in one ear and only one in the other. Of those with asymptomatic MEFs, in 80 the effusion was sterile or contained only nonpathogens in both ears, and in 19 contained one or more pathogens. Of these 19, ten had the same pathogen isolated from both ears; nine had a pathogen in one ear and sterile fluid or only nonpathogens in the other. Thus, in 31 children with AOM and nine with asymptomatic MEFs, results of cultures of MEF were different.

Otitis media with effusion (OME) is a common middle ear inflammatory disease in the pediatric population. This article determines concentrations of three functionally and metabolically distinct inflammatory mediators in middle ear effusions (MEE) and corresponding plasma of children with OME. One hundred two patients (mean age, 4.9 years) with persistent OME were studied. Middle ear effusions were collected from all subjects and plasma from a subset at the time of tympanostomy tube insertion. Histamine was assayed radioisotopically, 13,14-dihydro-15-keto-prostaglandin F2 alpha (stable PGF2 alpha metabolite) by radioimmunoassay, and neutrophil chemotactic factor of anaphylaxis by modified Boyden chamber. Mean MEE levels of the mediators (39 +/- 13 ng/mL, 462 +/- 179 pg/mL, and 264% +/- 57% positive control, respectively) were markedly higher than those of corresponding plasma (0.5 +/- 0.1 ng/mL, 285 +/- 127 pg/mL, and 47% +/- 5% positive control, respectively). The mean histamine content of mucoid effusions (43.2 +/- 56.9 ng/mL) was significantly higher than that of purulent (22.5 +/- 10.5 ng/mL) and serous (17.9 +/- 16.8 ng/mL) effusions. Higher histamine levels were observed in effusions positive for Haemophilus influenzae when compared with those with other pathogenic isolates. The high concentrations of these mediators in MEE and their potential for inducing or sustaining the inflammatory process supports a role in the pathogenesis of OME.

Bacteriologic investigation of middle ear effusion (MEE), external ear canal, and the nasopharynx was carried out on 458 patients with otitis media with effusion. Staphylococcus epidermidis was the most common bacteria in MEE, even after excluding the contaminants from the external ear canal, which had the same value of minimal inhibitory concentration as the paired MEE. The bacterial agreement of S epidermidis between MEE and the nasopharynx was extremely rare in contrast with Haemophilus influenzae, Streptococcus pneumoniae, and Branhamella catarrhalis, although the organism was also frequently isolated from the nasopharynx. Staphylococcus aureus, having the same minimal inhibitory concentration as that in the nasopharynx, was more frequently found in MEE than S epidermidis. The results suggest that S epidermidis found in MEE is not a pathogen, but rather a contaminant in many instances. Staphylococcus aureus seems to be a causative agent in otitis media with effusion.

Because Haemophilus influenzae is one of the most common pathogens in otitis media with effusion, we have investigated the antibody response in the serum and middle ear effusion (MEE) in nontypable H influenzae-induced experimental acute otitis media in the chinchilla, using an enzyme-linked immunosorbent assay. During acute otitis media, a reasonable antibody titer was observed: local antibody titers in the MEEs were equal to or greater than those of the serum samples for four of five MEE samples obtained at one week after inoculation. By two weeks, titers in both serum and MEE samples were increased significantly. However, the bacteria persisted in the middle ear cavity, even in the presence of increasing antibody titers, for up to five weeks after infection. The reason for this persistence of the bacteria in the middle ear is unknown.

The efficacy of a new third-generation cephalosporin, cefixime, in the treatment of acute otitis media resulting from infection with ampicillin-resistant, beta-lactamase-producing nontypable Haemophilus influenzae, was evaluated using the chinchilla animal model. The results showed that cefixime, administered in moderately low doses (8 mg/kg of body weight, two times per day), readily penetrated the chinchilla middle ear and rapidly sterilized the effusion. The data also suggest that the effusions were resolved more quickly in the cefixime-treated group compared with a group of animals treated with ampicillin or an untreated control group. No adverse side effects were noted in the cefixime-treated animals. The results of this study warrant the testing of cefixime for acute otitis media in the clinical setting.

Because bacteria are known to persist in middle ear effusions for extended periods of time despite the presence of increasing titers of specific antibody in both sera and middle ear fluids in humans, we examined the ability of postinfection serum to opsonize Haemophilus influenzae (nontypable and type b) for phagocytosis by middle ear macrophages in chinchillas. Our data indicated that preopsonization of both strains of H influenzae enhanced phagocytosis by macrophages recruited to the middle ear following intrabullar instillation of keyhole limpet hemocyanin. Both the total number of bacteria ingested and the percentage of macrophages phagocytizing were significantly greater in the presence of postinfection serum than preinfection serum for all animals tested.