A pre- and postoperative bacteriological study of chronic suppurative otitis media

Bacterial strain changes during chronic otitis media surgery

OBJECTIVE

Cultures obtained from pre-operative middle-ear swabs from patients with chronic otitis media have traditionally been used to guide antibiotic selection. This study investigated changes in the bacterial strains of the middle ear during chronic otitis media surgery.

METHODS

Pre-operative bacterial cultures of otorrhoea, and peri-operative cultures of the granulation tissue in either the middle ear or mastoid cavity, were obtained. Post-operative cultures were selectively obtained when otorrhoea developed after surgery.

RESULTS

Bacterial growth was observed in 45.5 per cent of pre-operative cultures, 13.5 per cent of peri-operative cultures and 4.5 per cent of post-operative cultures. Methicillin-resistant Staphylococcus aureus was identified as the most common bacteria in all pre-operative (32.4 per cent), peri-operative (52.4 per cent) and post-operative (71.4 per cent) tests, and the percentage of Methicillin-resistant S aureus increased from the pre- to the post-operative period.

CONCLUSION

The bacterial culture results for post-operative otorrhoea showed low agreement with those for pre-operative or peri-operative culture, and strain re-identification was required.

Current concepts in the pathogenesis and treatment of chronic suppurative otitis media

Otitis media (OM) is an inflammation of the middle ear associated with infection. Despite appropriate therapy, acute OM (AOM) can progress to chronic suppurative OM (CSOM) associated with ear drum perforation and purulent discharge. The effusion prevents the middle ear ossicles from properly relaying sound vibrations from the ear drum to the oval window of the inner ear, causing conductive hearing loss. In addition, the inflammatory mediators generated during CSOM can penetrate into the inner ear through the round window. This can cause the loss of hair cells in the cochlea, leading to sensorineural hearing loss. Pseudomonas aeruginosa and Staphylococcus aureus are the most predominant pathogens that cause CSOM. Although the pathogenesis of AOM is well studied, very limited research is available in relation to CSOM. With the emergence of antibiotic resistance as well as the ototoxicity of antibiotics and the potential risks of surgery, there is an urgent need to develop effective therapeutic strategies against CSOM. This warrants understanding the role of host immunity in CSOM and how the bacteria evade these potent immune responses. Understanding the molecular mechanisms leading to CSOM will help in designing novel treatment modalities against the disease and hence preventing the hearing loss.

Nasal Colonization of Methicillin-Resistant Staphylococcus aureus in Patients with Chronic Suppurative Otitis Media

Background and Objectives

Methicillin-resistant Staphylococcus aureus (MRSA) is one of major pathogens in patients with chronic suppurative otitis media (CSOM). In addition to intrinsic MRSA infection of the mastoid air cell system, nasal colonization of MRSA, a known predictor of postoperative surgical site infection, may pose increased risk of postoperative complications. The purpose of this study is to describe microbiology of preoperative nasal swab screening and localized middle ear specimens in patients undergoing otologic surgeries.

Subjects and Methods

Forty-nine consecutive patients with CSOM who underwent middle ear surgery were included. Preoperative nasal swabs for MRSA, and preoperative and intraoperative middle ear swabs were collected and compared for pathogens.

Results

Preoperative nasal swab screening confirmed MRSA colonization in 3/49 patients (6.1%) and methicillin-resistant coagulase-negative Staphylococcus (MRCNS) in 9/49 patients (18.4%). Correlation with preoperative culture results and nasal swab screening results were compatible in 2/4 patients with positive nasal swab for MRSA and 1/9 patients with positive nasal swab for MRCNS. Postoperative conversion to MRSA was observed in 3 patients.

Conclusions

The rate of nasal MRSA colonization among patients with CSOM was higher than among the general community. Preoperative MRSA colonization was associated with MRSA from middle ear specimens. Further studies are warranted to investigate the possible benefit of preoperative treatment of MRSA colonized patients undergoing middle ear surgeries.

Preoperative, intraoperative, and postoperative results of bacterial culture from patients with chronic suppurative otitis media

BACKGROUND

Cultures obtained from preoperative middle ear swabs from patients with chronic suppurative otitis media (CSOM) have traditionally been used to guide antibiotic selection. However, little is known about changes in the bacterial flora during surgery.

OBJECTIVE

To analyze preoperative, intraoperative, and postoperative bacterial cultures of CSOM patients who underwent tympanomastoidectomy.

METHODS

We retrospectively reviewed the medical records of 244 patients (113 male and 131 female subjects; 252 ears) diagnosed with CSOM between January 2006 and December 2008. Middle ear swabs and mastoid granulation tissue were collected preoperatively and intraoperatively, respectively. We also cultured middle ear swabs from patients with postoperative otorrhea.

RESULTS

The most commonly identified preoperative pathogenic bacterial species was methicillin-resistant Staphylococcus aureus (MRSA). There were no statistical differences in prevalence of preoperative bacterial pathogens between patients with and without cholesteatoma. No bacteria were observed in 34.1% of preoperative or 76.6% of intraoperative cultures. Patients preoperatively positive for coagulase-negative Staphylococcus, S. aureus, or Pseudomonas aeruginosa remained positive intraoperatively. Of the patients preoperatively negative for bacteria and those positive for fungi, 6.9% and 20.0%, respectively, were positive for bacteria, including MRSA, intraoperatively. Of the patients that were preoperatively positive for bacteria, 16.7% to 50.0% was intraoperatively positive for different pathogens from previous results. Patients with postoperative otorrhea yielded the highest culture rates of MRSA, preoperatively, intraoperatively, and postoperatively.

CONCLUSION

Although the similarities between preoperative and intraoperative culture results were relatively high, remaining or different pathogens also may have been present from intraoperative mastoid granulation tissue culture. Patients with preoperative MRSA were at high risk of postoperative otorrhea.

Innate immunity and the role of defensins in otitis media

Otitis media is the most common pediatric disease in developed countries and a significant cause of morbidity and hearing loss in developing countries. The innate immune system is essential to protecting the middle ear from infection. Defensins, broad-spectrum cationic antimicrobial peptides, have been implicated in prevention of and the early response to acute otitis media; however, the mechanisms by which defensins and other antimicrobial molecules mediate this protection have not been completely elucidated. In both animal otitis media models and human middle ear epithelial cell culture models, β-defensins are highly induced and effectively kill the common pathogens associated with otitis media. We review the importance of innate immunity in protecting the middle ear and recent advances in understanding the roles of defensins and other antimicrobial molecules in the prevention and treatment of otitis media. The extremely high prevalence of otitis media, in spite of sophisticated innate and adaptive immune systems, is a vexing problem for clinicians and scientists. We therefore also review mechanisms by which bacteria evade innate immune defenses.

Demographics and microbiology of otorrhea through patent tubes failing ototopical and/or oral antibiotic therapy

OBJECTIVES

Posttympanostomy tube otorrhea (PTTO) results in significant health care cost and decreased satisfaction with care. The authors reviewed PTTO failing initial ototopical and/or oral antibiotic therapy and microbiology/susceptibility data from cultures.

STUDY DESIGN

Case series with chart review.

SETTING

A community university satellite ambulatory clinic and the outpatient clinic of a children's hospital.

METHODS

Review of 202 patients with 228 discrete episodes of culture-positive otorrhea from January 2004 to January 2009.

RESULTS

PTTO occurred an average of 13 months after tube placement. Median otorrhea duration was 21 days (mean, 42 days). A mean of 1.6 visits (range, 1-6) to the pediatric otolaryngology office was required for PTTO resolution. Ototopical therapy was reported used in 198 of 228 (87%) episodes of otorrhea prior to pediatric otolaryngology visit. Nearly 50% of patients were prescribed at least 1 or more courses of systemic antibiotics. Staphylococcus aureus accounted for 52% of the organisms cultured, with 57% methicillin-resistant S aureus (MRSA). S aureus resistance to clindamycin was high (49%) and resistance to levofloxacin was low (1.8%). MRSA was 68% clindamycin resistant, much higher than both ours and the children's hospital's clindamycin resistance rate of MRSA cultured from all other body sites.

CONCLUSIONS

PTTO that presents as having failed ototopical and/or oral antibiotics most commonly consists of S aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa. MRSA is highly prevalent in this population. It is not necessary to culture PTTO that presents to an otolaryngology office, as resistance to levofloxacin was only 1.8%. It is unclear why the same fluoroquinolone ototopical therapy that failed initially is often successful in treating PTTO after otolaryngologist visit.