A 16-year survey of changes in bacterial isolates associated with chronic suppurative otitis media

Efficacy of antibiotic prophylaxis prior to tympanoplasty for contaminated cholesteatoma

OBJECTIVES

To evaluate the efficacy of combined antistaphylococcal and antipseudomonal preoperative antibiotics for preventing surgical site infections following tympanoplasty and mastoidectomy with contaminated cholesteatoma.

STUDY DESIGN

Retrospective chart review.

METHODS

Medical records of patients who underwent tympanoplasty ± mastoidectomy for cholesteatoma were reviewed. Only cases considered to have contaminated or dirty surgical fields were included. The primary outcome measure was occurrence of postoperative surgical site infections, perichondritis, pinna abscess, periotic cellulitis, or periotic abscess requiring systemic antibiotic therapy or surgical intervention.

RESULTS

The charts of 326 patients who underwent tympanoplasty ± mastoidectomy were reviewed. Of those, 195 met inclusion criteria. Preoperative antibiotics included clindamycin and ceftazidime or gentamicin. Patients treated with no perioperative antibiotics had a surgical site infection rate of 11%, and those treated with perioperative antibiotics had a rate of 1% (P = 0.02).

CONCLUSION

Administration of preoperative antibiotics to cover staphylococcal and pseudomonal species may prevent surgical site infections with tympanoplasty ± mastoidectomy for contaminated cholesteatoma.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:2363-2366, 2016.

Radiographic and micro-computed tomographic imaging of lipopolysaccharide-mediated bone resorption

OBJECTIVES

Chronic otitis media and cholesteatomas cause hearing loss as a result of bony erosion. This bone resorption is known to be more aggressive when cholesteatomas become infected. The most common organism isolated from both diseases is the gram-negative bacterium Pseudomonas aeruginosa. Lipopolysaccharide (LPS), a major virulence factor found in the gram-negative bacterial cell wall, is well known to incite inflammatory bone resorption. The mechanisms underlying this process, however, are poorly understood. In this study, we developed a mouse model of calvarial osteolysis in which resorption was reliably imaged by plain radiography and micro-computed tomography (micro-CT).

METHODS

A murine calvarial model was developed to study bone resorption induced by P aeruginosa LPS. Calvariae from wild-type and knockout mice used in this model were imaged by plain radiography and micro-CT.

RESULTS

A high degree of correlation between plain radiography and micro-CT was identified (R2 = 0.8554). Furthermore, maximal LPS-induced bone resorption required functioning toll-like receptor (TLR) 2, TLR4, and myeloid differentiation factor 88 (MyD88).

CONCLUSIONS

We have developed a successful model of inflammatory osteolysis in which plain radiography can reliably delineate induced bone resorption. In vivo, we have shown that P aeruginosa LPS signals via TLR2, as well as TLR4 through MyD88.

Lipopolysaccharide-induced osteoclastogenesis from mononuclear precursors: a mechanism for osteolysis in chronic otitis

Osteoclasts are the only cells capable of carrying out bone resorption and therefore are responsible for the osteolysis seen in infectious diseases such as chronic otitis media and infected cholesteatoma. Pseudomonas aeruginosa is the most common organism isolated from these infectious middle ear diseases. In this study, we examined the mechanisms by which P. aeruginosa lipopolysaccharide (LPS) stimulates osteoclastogenesis directly from mononuclear osteoclast precursor cells. Osteoclast precursors demonstrated robust, bone-resorbing osteoclast formation when stimulated by P. aeruginosa LPS only if previously primed with permissive, sub-osteoclastogenic doses of receptor activator of NF-kappaB ligand (RANKL), suggesting that LPS is osteoclastogenic only during a specific developmental window. Numerous LPS-elicited cytokines were found to be released by osteoclast precursors undergoing P. aeruginosa LPS-mediated osteoclast formation. Two lines of evidence suggest that several cytokines promote Oc formation in an autocrine/paracrine manner. First, inhibition of several cytokine pathways including TNF-alpha, IL-1, and IL-6 block the osteoclastogenesis induced by LPS. Secondly, increased expression of the receptors for TNF-alpha and IL-1 was demonstrated by real-time quantitative polymerase chain reaction. Such a mechanism has not previously been established and demonstrates the ability of osteoclast precursors to autonomously facilitate bone destruction.

Construction and characterization of a highly redundant Pseudomonas aeruginosa genomic library prepared from 12 clinical isolates: application to studies of gene distribution among populations

OBJECTIVE

To create, array, and characterize a pooled, high-coverage, genomic library composed of multiple biofilm-forming clinical strains of the opportunistic pathogen, Pseudomonas aeruginosa (PA). Twelve strains were obtained from patients with otorrhea, otitis media, and cystic fibrosis as a resource for investigating: difference in the transcriptomes of planktonic and biofilm envirovars; the size of the PA supragenome and determining the number of virulence genes available at the population level; and the distributed genome hypothesis.

METHODS

High molecular weight genomic DNAs from 12 clinical PA strains were individually hydrodynamically sheared to produce mean fragment sizes of approximately 1.5 kb. Equimolar amounts of the 12 sheared genomic DNAs were then pooled and used in the construction of a genomic library with approximately 250,000 clones that was arrayed and subjected to quality control analyses.

RESULTS

Restriction endonuclease and sequence analyses of 686 clones picked at random from the library demonstrated that >75% of the clones contained inserts larger than 0.5 kb with the desired mean insert size of 1.4 kb. Thus, this library provides better than 4.5x coverage for each of the genomes from the 12 components clinical PA isolates. Our sequencing effort ( approximately 1 million nucleotides to date) reveals that 13% of the clones present in this library are not represented in the genome of the reference P. aeruginosa strain PA01.

CONCLUSIONS

Our data suggests that reliance on a single laboratory strain, such as PA01, as being representative of a pathogenic bacterial species will fail to identify many important genes, and that to obtain a complete picture of complex phenomena, including bacterial pathogenesis and the genetics of biofilm development will require characterization of the P. aeruginosa population-based supra-genome.

Intracranial abscesses associated with chronic suppurative otitis media

Intracranial abscesses are serious complications of chronic suppurative otitis media (COM). This study included 32 patients presenting with intracranial abscesses from 780 patients hospitalized for treatment of COM. The 32 patients had 59 intracranial complications. Perisinus abscess (13 of 32) was the most common intracranial abscess, followed by temporal lobe abscess (8 of 32), epidural abscess (7 of 32), cerebellar abscess (6 of 32) and subdural empyema (2 of 32). Headache (93%), fever (87%) and altered mental status (62%) were the most common presenting symptoms and signs, along with symptoms of COM. All patients were treated with intravenous antibiotics and canal wall down mastoidectomy. Cholesteatoma with granulation tissue and bony defects at the sinus plate and/or dural plate were seen in most of the patients. Gram negative bacilli and anaerobes were the most common organisms cultured from the abscesses. Three patients had neurological sequels. One patient died. The early diagnosis of these complications requires a high index of suspicion and imaging studies. A multidisciplinary and coordinated approach is important for the management of these patients.

Susceptibility of microorganisms isolated from chronic suppurative otitis media to ciprofloxacin

In order to evaluate the susceptibility of the microorganisms isolated from chronic suppurative otitis media to ciprofloxacin, cultures of specimens from 127 patients with chronic suppurative otitis media and their antibiotic sensitivity results were examined. The most common aerobic isolates were Pseudomonas sp., Proteus sp., and Staphylococcus aureus with recovery rates of 40.7%, 21.6% and 19.1% respectively. Sensitivity results showed that 6.2% of Pseudomonas isolates, 2.9% of Proteus isolates, 10% of Staphylococcus aureus isolates and 8.3% of Escherichia coli isolates were resistant to ciprofloxacin.