Bacteriology of chronic otitis media with effusion

Biofilm-Forming Bacteria Implicated in Complex Otitis Media in Children in the Post-Heptavalent Pneumococcal Conjugate Vaccine (PCV7) Era

Background: Chronic media with effusion (COME) and recurrent acute otitis media (RAOM) are closely related clinical entities that affect childhood. The aims of the study were to investigate the microbiological profile of otitis-prone children in the post-PCV7 era and, to examine the biofilm-forming ability in association with clinical history and outcome during a two-year post-operative follow-up. Methods: In this prospective study, pathogens from patients with COME and RAOM were isolated and studied in vitro for their biofilm-forming ability. The minimum inhibitory concentrations (MIC) of both the planktonic and the sessile forms were compared. The outcome of the therapeutic method used in each case and patient history were correlated with the pathogens and their ability to form biofilms. Results: Haemophilus influenzae was the leading pathogen (35% in COME and 40% in RAOM), and Streptococcus pneumoniae ranked second (12% in COME and 24% in RAOM). Polymicrobial infections were identified in 5% of COME and 19% of RAOM cases. Of the isolated otopathogens, 94% were positive for biofilm formation. Conclusions: This is the first Greek research studying biofilm formation in complex otitis media-prone children population in the post-PCV7 era. High rates of polymicrobial infections, along with treatment failure in biofilms, may explain the lack of antimicrobial efficacy in otitis-prone children.

Predominant Bacteria Detected from the Middle Ear Fluid of Children Experiencing Otitis Media: A Systematic Review

BACKGROUND

Otitis media (OM) is amongst the most common childhood diseases and is associated with multiple microbial pathogens within the middle ear. Global and temporal monitoring of predominant bacterial pathogens is important to inform new treatment strategies, vaccine development and to monitor the impact of vaccine implementation to improve progress toward global OM prevention.

METHODS

A systematic review of published reports of microbiology of acute otitis media (AOM) and otitis media with effusion (OME) from January, 1970 to August 2014, was performed using PubMed databases.

RESULTS

This review confirmed that Streptococcus pneumoniae and Haemophilus influenzae, remain the predominant bacterial pathogens, with S. pneumoniae the predominant bacterium in the majority reports from AOM patients. In contrast, H. influenzae was the predominant bacterium for patients experiencing chronic OME, recurrent AOM and AOM with treatment failure. This result was consistent, even where improved detection sensitivity from the use of polymerase chain reaction (PCR) rather than bacterial culture was conducted. On average, PCR analyses increased the frequency of detection of S. pneumoniae and H. influenzae 3.2 fold compared to culture, whilst Moraxella catarrhalis was 4.5 times more frequently identified by PCR. Molecular methods can also improve monitoring of regional changes in the serotypes and identification frequency of S. pneumoniae and H. influenzae over time or after vaccine implementation, such as after introduction of the 7-valent pneumococcal conjugate vaccine.

CONCLUSIONS

Globally, S. pneumoniae and H. influenzae remain the predominant otopathogens associated with OM as identified through bacterial culture; however, molecular methods continue to improve the frequency and accuracy of detection of individual serotypes. Ongoing monitoring with appropriate detection methods for OM pathogens can support development of improved vaccines to provide protection from the complex combination of otopathogens within the middle ear, ultimately aiming to reduce the risk of chronic and recurrent OM in vulnerable populations.

In VitroStreptococcus pneumoniae Biofilm Formation and In Vivo Middle Ear Mucosal Biofilm in a Rat Model of Acute Otitis Induced by S. pneumoniae

Objectives

Streptococcus pneumoniae is one of the most common pathogens of otitis media (OM) that exists in biofilm, which enhances the resistance of bacteria against antibiotic killing and diagnosis, compared to the free-floating (planktonic) form. This study evaluated biofilm formation by S. pneumoniae on an abiotic surface and in the middle ear cavity in a rat model of OM.

Methods

In vitro biofilm formation was evaluated by inoculation of a 1:100 diluted S. pneumoniae cell suspension in a 96-well microplate. Adherent cells were quantified spectrophotometrically following staining with crystal violet by measurement of optical density at 570 nm. The ultrastructure of pneumococcal biofilm was assessed by scanning electron microscopy (SEM). For in vitro biofilm study, S. pneumoniae cell suspensions containing 1×10⁷ colony forming units were injected through transtympanic membrane into the middle ear cavity of Sprague Dawley rats. The ultrastructure of middle ear mucus was observed by SEM 1 and 2 weeks post-inoculation.

Results

The in vitro study revealed robust biofilm formation by S. pneumoniae after 12-18 hours of incubation in high glucose medium, independent of exogenously supplied competence stimulating peptide and medium replacement. Adherent cells formed three-dimensional structures approximately 20-30 µm thick. The in vivo study revealed that ciliated epithelium was relatively resistant to biofilm formation and that biofilm formation occurred mainly on non-ciliated epithelium of the middle ear cavity. One week after inoculation, biofilm formation was high in 50% of the treated rats and low in 25% of the rats. After 2 weeks, biofilm formation was high and low in 25% and 37.5% of rats, respectively.

Conclusion

The results imply that glucose level is important for the S. pneumoniae biofilm formation and S. pneumoniae biofilm formation may play important role in the pathophysiology of OM.

Biofilms and chronic otitis media: an initial exploration into the role of biofilms in the pathogenesis of chronic otitis media

PURPOSE

The aim of the study was to compare the extent of biofilm infection in percentage of mucosal surface area of adenoids removed from children with otitis media with effusion (OME) vs those with recurrent acute otitis media (RAOM) and obstructive sleep apnea (OSA).

MATERIALS AND METHODS

Comparative microanatomical investigation of adenoid mucosa using scanning electron microscopy obtained from 30 children with OME, RAOM, and OSA was used in this study. Seventeen males and 13 females ranging in age from 9 months to 10 years were included in this study. Percentage of biofilm surface area involvement was the main measure.

RESULTS

Adenoids removed from patients with OME had moderately dense mature biofilms covering the mucosal surface with a mean of 27.7% of their mucosal surface covered with mature biofilms. These results were distinct from results obtained from patients diagnosed with RAOM and OSA with means of 97.6% and 0.10% of their mucosal surfaces covered with mature biofilms, respectively. These differences were statistically significant at P < .0001.

CONCLUSIONS

Adenoids removed from patients with OME were characterized by distinctly different percentage of biofilm mucosal surface area coverage, with significantly more biofilm presence than OSA patients but significantly less biofilm presence than RAOM patients. Although previous investigations have supported a dominant role of nasopharyngeal biofilms in RAOM pathogenesis, these results suggest nasopharyngeal biofilms may play a different role in the pathogenesis of OME and that this clinical entity may be more multifactorial in nature.

The ciliary beat frequency of middle ear mucosa in children with chronic secretory otitis media

The chronic secretory otitis media (CSOM) is a common disease in children. Its cardinal symptoms are recurrent middle ear effusions and conductive hearing loss. Until today, the pathophysiological mechanism of this disease remains unknown. The correlation with adenoids and tubal dysfunction during childhood seems to be obvious, but the origin of middle ear effusions still has to be clarified. It is known that the CSOM affects the mucociliary system in several ways. In order to find out more about these correlations, the ciliary beat frequency was examined in 123 samples of infantile middle ear mucosa suffering from CSOM. Samples were surveyed using a stroboscopic microscopy method. The results of this study showed a significant decrease of ciliary beat frequency (CBF) to an average of 7.4 s(-1) in children with a CSOM. The healthy group of control showed a frequency of 10.1 s(-1). The measured CBF dataset was correlated with microbiological findings. We found a typical bacterial profile in nearly all the cases that were examined but were unable to find a specific bacterium decreasing CBF. This study provides evidence for the diminution of CBF in cases of CSOM in comparison to a healthy control group. Our findings emphasize the importance of stopping the vicious circle of recurrent effusions by paracentesis or grommet insertion.

Presence of herpesviruses in middle ear fluid of children with otitis media with effusion

BACKGROUND

Otitis media with effusion (OME) is a disease that frequently occurs in children. Etiopathogenesis of the diseases has not been completely elucidated. There are limited numbers of studies on the presence of herpesviruses in otitis media cases with OME. The present study was undertaken to determine the rate of some herpesviruses in OME cases of children.

METHODS

A total of 92-middle ear fluids were collected from 51 children. The samples were analyzed using polymerase chain reaction (PCR) for detection of herpesviruses including Herpes simplex virus (HSV), cytomegalovirus (CMV), Varicella zoster virus (VZV), and Epstein-Barr virus (EBV).

RESULTS

PCR analysis of the 92 samples showed that genomes of EBV in 12 (13.04%), HSV in seven (7.60%), CMV in five (5.43%), and VZV in three (3.26%) were present. Two of these samples were positive for both HSV and EBV genomes. Therefore, 25 (27.17%) of the samples were determined to be infected with any of the herpesviruses tested.

CONCLUSIONS

In the present study, herpesviruses were determined at a high rate in middle ear fluids of children with OME. However, the present study is a preliminary study and more extensive studies, especially experimental studies, are required to elucidate the role of herpesviruses in pathogenesis of OME and whether there is a relation between rate of herpesviruses in OME cases, and the reactivation of latent infections.

Direct evidence of bacterial biofilms in otitis media

OBJECTIVES/HYPOTHESIS

Bacteriologic studies of otitis media with effusion (OME) using highly sensitive techniques of molecular biology such as the polymerase chain reaction have demonstrated that traditional culturing methods are inadequate to detect many viable bacteria present in OME. The presence of pathogens attached to the middle-ear mucosa as a bacterial biofilm, rather than as free-floating organisms in a middle-ear effusion, has previously been suggested to explain these observations. The suggestion has been speculative, however, because no visual evidence of such biofilms on middle-ear mucosa has heretofore been collected. The hypotheses motivating the current study were: 1) biofilms of nontypable Hemophilus influenzae will form on the middle-ear mucosa of chinchillas in an experimental model of OME, 2) these biofilms will exhibit changes in density or structure over time, and 3) biofilms are also present on tympanostomy tubes in children with refractory post-tympanostomy otorrhea. The objective of this study was to collect visual evidence of the formation of bacterial biofilms in these situations.

STUDY DESIGN

Laboratory study of bacteriology in an animal model and on medical devices removed from pediatric patients.

METHODS

Experimental otitis media was induced in chinchillas by transbullar injection of nontypable H. influenzae. Animals were killed in a time series and the surface of the middle-ear mucosa was examined by scanning electron microscopy (SEM) for the presence of bacterial biofilms. Adult and fetal chinchilla uninfected controls were similarly examined for comparison. In addition, tympanostomy tubes that had been placed in children's ears to treat OME and removed after onset of refractory otorrhea or other problems were examined by SEM and by confocal scanning laser microscopy for bacterial biofilms, and compared with unused control tubes.

RESULTS

Bacterial biofilms were visually detected by SEM on the middle-ear mucosa of multiple chinchillas in which H. influenzae otitis media had been induced. Qualitative evaluation indicated that the density and thickness of the biofilm might increase until at least 96 hours after injection. The appearance of the middle-ear mucosa of experimental animals contrasted with that of uninjected control animals. Robust bacterial biofilms were also visually detected on tympanostomy tubes removed from children's ears for clinical reasons, in contrast with unused control tubes.

CONCLUSIONS

Bacterial biofilms form on the middle-ear mucosa of chinchillas in experimentally induced H. influenzae otitis media and can form on tympanostomy tubes placed in children's ears. Such biofilms can be directly observed by microscopy. These results reinforce the hypothesis that the bacterial aggregates called biofilms, resistant to treatment by antibiotics and to detection by standard culture techniques, may play a major etiologic role in OME and in one of its frequent complications, post-tympanostomy otorrhea.

High incidence of Alloiococcus otitis in otitis media with effusion

BACKGROUND

The etiology of otitis media with effusion (OME) is unclear. Although the majority of effusions show inflammation, culture methods yield positive results for bacteria in only 20 to 30% of cases.

METHODS

The polymerase chain reaction was used for detection of three upper respiratory tract pathogens, Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae, and a fairly recently described bacterium, Alloiococcus otitis (A. otitidis), that is solely found in OME. The study included 67 middle ear effusions that were collected from 48 pediatric OME patients during ventilation tube placement.

RESULTS

PCR tested positive for 57 (85.1%) of the middle ear effusions. Thirty-one (46.3%) A. otitis-, 12 (17.9%) H. influenzae-, 25 (37.3%) M. catarrhalis- and 14 (20.9%) S. pneumoniae-positive effusions were obtained. All four study organisms showed similar distribution in effusions of various duration (P = 0.72) and in different effusion types (P = 0.59). Only the proportion of M. catarrhalis-positive effusions was lowered by recent antimicrobial therapy (P < 0.05). Although the study organisms had equal distributions among singly and multiply positive specimens (P = 0.90), A. otitis was detected significantly more often with one of the three other species (15 of 19, 78.9%) than the other species with each other (4 of 19, 21.1%, P < 0.001).

CONCLUSIONS

The findings suggest a bacterial etiology for OME. Association of A. otitis with the three other species implies that this organism might have the capability of augmenting bacterial colonization in the middle ear.

Double-blind randomised trial of co-amoxiclav versus placebo for persistent otitis media with effusion in general practice

BACKGROUND

The treatment of persistent otitis media with effusion (OME) remains controversial, but this condition is the commonest reason for children to require ear, nose, and throat (ENT) surgery. Trials of antibiotics are inconclusive, are often weak methodologically, and have not been done in general practice. Our aim was a trial of an antibiotic for OME in such a population.

METHODS

433 children, aged 6 months to 6 years, with OME from 57 general practices entered a 3-month watchful waiting period. Of 223 (52%) with persistent bilateral OME, 162 were randomised double-blind to receive co-amoxiclav suspension (20 mg/kg amoxicillin, 5 mg/kg clavulanate potassium) or matching placebo, orally three times a day for 14 days. All cases also received xylometazoline 0.25% decongestant nosedrops thrice daily. Of the 61 not randomised, 13 children were referred to an ENT surgeon and parents refused consent in 48 cases. The main outcome measures were persistent OME in both ears and in one or both ears, as assessed clinically and by tympanometry. Analysis was by intention-to-treat.

FINDINGS

79 children in the treatment group and 70 in the placebo group were analysed for efficacy. 3 withdrew in the co-amoxiclav group (2 lost to follow-up, 1 due to side-effects); 6 withdrew in the placebo group (5 and 1, respectively). In addition, 4 tympanograms were uninterpretable in the controls. Compliance was over 90% in both groups. Persistent OME in both ears and in one or both ears were found at significantly lower rates in the co-amoxiclav group than in the controls at the 2-week follow-up: 53 vs 84% and 77 vs 93%, respectively. Odds ratios adjusted for sex, history of adenoidectomy, and upper respiratory tract infection at follow-up were 0.25 (95% CI 0.11, 0.58, p = 0.001) and 0.30 (0.10, 0.89, p = 0.03), respectively. Parents of children in the co-amoxiclav group reported significantly more side-effects than those of control children (44 vs 22%, p = 0.03). Side-effects were mostly gastrointestinal and mild.

INTERPRETATION

Our study in a general-practice setting confirmed the positive short-term effect of antibiotic treatment for persistent middle-ear infection. Before referral to an ENT surgeon, children with persistent OME presenting to general practitioners could be considered for such treatment, depending on the individual child and possible adverse sequelae.

The incidence of bacteria in middle ear effusions

Otitis media with effusion (OME) is a common condition in paediatric ENT practice. Whilst surgical management is in many cases the mainstay of treatment for resistant OME, the use of antibiotics has been advocated by some authorities. Over one quarter of middle ear effusions analysed in this study contained potentially pathogenic bacteria. Antibiotics may be of value in the treatment of OME in these children.

Incidence of adenovirus and respiratory syncytial virus in chronic otitis media with effusion using the polymerase chain reaction

The aim of this study is to investigate the role of adenovirus and respiratory syncytial virus in the cause of chronic otitis media with effusion by use of the polymerase chain reaction for detection. The polymerase chain reaction has proved to be more sensitive and specific than viral cultures and immunoassays in the detection of viruses in other specimens. Adenovirus and respiratory syncytial virus were chosen because these viruses have been the most commonly isolated viruses in middle ear effusions in studies using other techniques. The effusions (132 total) were sterilely collected from 88 children undergoing myringotomy and ventilation tube placement for chronic otitis media with effusion. Nine (6.8%) specimens were positive for adenovirus by the polymerase chain reaction, and 13 (9.9%) were positive for respiratory syncytial virus by the polymerase chain reaction. Only one specimen was positive for adenovirus and respiratory syncytial virus by viral culture and immunofluorescence, respectively. Our results show that the polymerase chain reaction can be used to detect adenovirus and respiratory syncytial virus in chronic middle ear effusions and that PCR is more sensitive than viral culture and immunofluorescence techniques.

Factors associated with positive bacteriological cultures of chronic middle ear effusions

Pathogenic bacteria have been isolated from middle ear effusions in a number of studies. Our aim was to identify factors which predispose to patients having positive cultures. Over a 1-year period, prospective data were collected on patients admitted for myringotomy. Middle ear effusions were collected at the time of surgery using specially designed traps, and underwent microscopy and culture. Data on local weather parameters were obtained from the Meteorological Office in Edinburgh, UK and compared with the patterns of positive cultures. A higher proportion of cultures were positive in October, November and December and in February and May than in the other months of the years. We were not able to relate these variations to any of the meteorological data, with the possible exception of relative humidity, or to any other variable.

The microbiology of acute and chronic sinusitis and otitis media:a review

There exists no real controversy about the role of aerobic bacteria in acute sinusitis and in acute otitis media. The "infernal trio" Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are by far the most common pathogens in these acute infections. On the contrary, there is still much debate about the normal flora of the paranasal sinuses and the middle ear, although there are some reports of the presence of anaerobes and aerobes in the majority of the normal paranasal sinuses. In chronic sinusitis bacteriological cultures show a greater variation than those in acute sinusitis. Nonetheless, it is demonstrated in most studies that besides the "infernal trio" additional bacteria are present, including anaerobes and gram negative bacteria. In otitis media with effusion (OME) we find the same bacteria as in acute otitis media (AOM) and a pathologic flora in the nasopharynx seems to be important for both AOM and OME. In chronic otitis cultures are nearly always positive and reveal Pseudomonas species, Klebsiella pneumoniae, Staphylococcus aureus, Proteus species and anaerobes.