Safe and effective treatment for otitis externa.
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The purposes of this study were to determine whether ciprofloxacin disk diffusion susceptibility test (DDT) results could be used to assess the in vitro susceptibility of otic bacterial organisms to enrofloxacin and to determine the effect of concurrent enrofloxacin administration on the DDT results for enrofloxacin and ciprofloxacin. Thirty dogs with end-stage otitis externa undergoing unilateral total ear canal ablation were enrolled. The dogs were randomized to one of four enrofloxacin-treatment groups or to the control group. Each dog in the treatment groups received two intravenous doses of enrofloxacin prior to surgical removal of the middle-ear tissue while the control group did not receive any enrofloxacin. One dog was excluded from the study as no middle-ear tissue was removed during surgery. Twenty-four dogs were in the enrofloxacin-treatment groups and five dogs were in the control group. In 12 of 29 dogs (41.4%), 14 of 82 (17.1%) of bacteria had discrepancies in DDT results for enrofloxacin and ciprofloxacin. Discrepancies between the control group and treatment groups were not significantly different even though the percentage of discrepancies for the combined treatment group was 19.4% compared to 6.7% for the control group. In this study, ciprofloxacin DDT results were not an accurate indicator of the in vitro susceptibility of enrofloxacin for bacteria isolated from the middle-ear tissue of dogs with end-stage otitis.
OBJECTIVES: Proteases are known to contribute to the pathogenesis of chronic inflammatory skin conditions such as atopic dermatitis and psoriasis. Inhibition of these proteases has shown promise in the treatment of these skin conditions. The purpose of this study was to measure the matrix metalloproteinases (MMP) and human neutrophil elastase (HNE) activities in chronic otitis externa (COE) and to determine whether administration of protease inhibitors recombinant alpha 1-antitrypsin (rAAT) and ilomastat might reduce these protease activities. STUDY DESIGN: Prospective and ex vivo. METHODS: Twenty-five ear canals with COE and 34 with no pathology (i.e., controls) were debrided and filled with saline. After a tragal pump and 1 to 2 minutes, the washes were collected and analyzed for MMP and HNE activities and the inhibitory activity of rAAT and ilomastat on these proteases, respectively. RESULTS: MMP and HNE levels were significantly higher (P = .0057 and .0112) in ears with COE than normal ears. MMP activity greater than 3 mAU/minute was observed in 30% of COE and 0% of controls (P = .0270). HNE activity greater than 3 mAU/minute was found in 77% of COE versus 7% of controls (P < .0001). Ilomastat and rAAT inhibited 60% of MMP and 98% of HNE activity, respectively, in COE ears. CONCLUSIONS: Elevated levels of proteases found in COE, MMP, and HNE may be inhibited with ilomastat and rAAT. The therapeutic potential of these protease inhibitors warrants investigation.
Over a 12-month period, nine patients were seen in a contact dermatitis clinic with an inflammatory dermatosis localized predominantly to the external auditory canal. Of these patients, four were found to have an allergic contact dermatitis which was exacerbating their dermatitis. All were allergic to one or more corticosteroids and topical antibiotics used in the treatment of their dermatitis. We would suggest that hypersensitivity to topical corticosteroids and other medicaments be considered in patients with otitis externa which fails to respond to treatment.
Pseudomonas aeruginosa LasB elastase gene (lasB) transcription depends on cell density-dependent quorum-sensing mechanisms of gene activation. Previously, we collected several non-mucoid P. aeruginosa veterinary isolates and showed that the total matrix protease phenotype was similar for isolates regardless of host and site of isolation. In contrast, isolates from chronic canine ear infections (otitis externa) were significantly more likely to exhibit less elastase activity as measured by elastin Congo red than from any other site [Clin. Diag. Lab. Immun. 8 (2001) 632]. In this study, we found that the elastase deficiency phenotype is stable upon passage in broth culture. Transcript amplification analyses indicated that the elastase deficiency appears to be strain-specific, with each isolate exhibiting a unique expression profile relative to strain PAO1. Although a number of strain-specific transcriptional differences were observed, the overall pattern that emerges is a quorum sensing deficiency among canine ear P. aeruginosa isolates.
Chronic external otitis may be divided into several diagnostic categories. Disposition for psoriasis, seborrhoeic and atopic eczema are main endogenous reasons. Exogenous pathogens for external otitis are microbes and allergens. There are numerous interrelations by coincidence of dispositional diseases, e.g. psoriasis and atopic eczema and by combination of exogenous and endogenous pathogens. This holds good for the yeast Pityrosporum ovale vs. orbiculare in seborrhoeic eczema and for the susceptibility to contact (type IV) and respiratory (type I) allergy in atopic individuals as well. Mycotic and bacterial, especially gram negative external otitis are linked to predisposing factors like eczema, long-term microbicidal therapy, hot and humid environment. Contact allergic external otitis may occur during long lasting local therapy with various substances including vehicles, the most common allergen being neomycin. Mucosal allergic reactions (Type I) in the upper respiratory tract may impair ventilation of the Eustachian tube and middle ear and therefore epithelial migration, as a drainage mechanism of the auditory canal. Examination should include functional assessment of the Eustachian tube and middle ear and allergy testing (patch, prick test). Preparations for local therapy should contain a limited number of constituents and avoid common allergens. Surgical procedures to reestablish ventilation of the middle ear are also a therapy for chronic external otitis.
Malignant external otitis (MEO) is a disease of the external auditive channel (EAC) due to Pseudomonas aeruginosa which usually involves individuals with diabetes mellitus. It may result in the invasion of the cranial base with cranial neuropathy and a high mortality rate despite therapy. We report the clinical features, diagnostic procedures, evolution and therapy of 8 patients with MEO, seven of which had cranial neuropathy. All patients have diabetes except one who had acquired immunodeficiency syndrome. All had otalgia, otorrhea and headache lasting for several months. Six patients had homolateral (as related to the MEO) facial palsy. One patient with bilateral MEO developed bilateral facial palsy and lesion of the cranial nerves VI (unilaterally) and IX through XII (bilaterally). In all patients P. aeruginosa was cultured from the EAC exudate scintigraphy with 99Tc showed uptake at medium ear and mastoid level in all 8 patients, suggesting a possible osteomyelitis. Scintigraphy with 67Ga was positive in the 6 cases where it was carried out, showing uptake in the soft tissues of the cranial base. Computed tomography was carried out in 6 patients, and it was useful to define the anatomical extent of the disease. The patients received different therapeutic schedules, particularly the combination of a betalactamic and aminoglucoside antibiotics. Follow up was characterized by common recurrences, and one patient died. The importance of early diagnosis and treatment to prevent the extension and recurrence of MEO are discussed. Cranial neuropathy is considered as a poor prognostic finding.
Polymerase chain reaction (PCR)-based detection and transcription of the gene encoding a potent virulence factor, the exotoxin A, were done on 32 isolates of Pseudomonas aeruginosa belonging to 23 genotypes. These isolates were obtained from 22 patients who were admitted to the emergency room in a medical center during a 5-month period with the diagnosis of either unilateral or bilateral otitis externa. Patients showed symptoms that ranged from mild to severe. PCR amplification of a 396-bp fragment of the gene encoding the exotoxin A was done on extracted DNA. Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) was performed on extracted RNA to detect exotoxin A gene mRNA transcripts. Quantitation of RT-PCR amplicons from P. aeruginosa isolates associated with mild and severe symptoms was determined by end-point titration of c-DNA and scanning of amplicons with the Storm Gel and Blot Imaging System. Data have shown that all of the 32 isolates of P. aeruginosa carry the exotoxin A gene, and all isolates with the exception of two had the exotoxin A transcription demonstrated by the production of a 396-bp amplicon from RT-PCR-amplified RNA. The remaining two isolates amplified fragments that were slightly smaller than the expected size. Additional studies are needed to characterize these two mRNA transcripts. Transcription levels of exotoxin A gene associated with severe symptoms were significantly more elevated than those associated with mild to moderate symptoms. Studies are under way to determine expression of P. aeruginosa exotoxin A by detecting quantitatively levels of the translated exotoxin A protein produced by isolates associated with severe and mild to moderate symptoms.
Infections of the ear canal may vary in terms of severity. Their frequency and morbidity qualify them as significant aquatic problems. The aquatic environment adds the conditional variable of moisture to the ear canal. Usually bacteria are introduced with the moisture and in the warm environment of the canal multiply, generate debris, invade the canal lining, and generate the symptoms of otitis externa. Fortunately, the incidence of this condition can be minimized by eliminating moisture in the canal. In situations where excessive moisture is likely to be introduced such as in swimmers, scuba divers, and deep sea divers the prophylactic measures of desiccation and acidification of the canal should be used. They are very effective. In the saturation diver, ear canal infections are not likely to resolve without interruption of diving activities. Individuals who have recurring ear canal infections require evaluation by an ear specialist to identify possible remedial problems that can trigger infection. Correction of anatomical problems or underlying dermatoses can prevent recurrences of OE.
BACKGROUND: Swab cytology of ear canals is one of the most useful and rapid methods to assess the presence of external ear infections. Smears are generally stained with rapid Romanowsky-type stains, with or without prior heat fixation. OBJECTIVES: The aim of this study was to compare 4 different methods of fixation and staining of ear swab cytology samples from dogs. METHODS: Eight dogs with otitis externa were selected from a dermatology referral population. A cotton swab was used to obtain ceruminous material from 12 ear canals. Four smears of each swab were prepared on glass slides (randomly identified as A, B, C, or D) and air-dried for cytologic examination. Samples marked A were stained with Dip Quick (Jorgensen Laboratories Inc, Loveland, CO, USA) after heat fixation; samples marked B were stained without heat fixation; samples marked C were heat-fixed and dipped only in the counterstain (the blue reagent) of Dip Quick; and samples marked D were dipped only in the counterstain, without heat fixation. Ten high-power fields (hpf; X100 oil immersion objective) in each slide were evaluated by 2 observers, and total numbers of keratinocytes, yeast, bacteria, and neutrophils were counted. Statistical comparison was performed using an ANOVA model applied after verifying the normal distribution of the data, and using nonparametric sign tests and Wilcoxon signed rank tests. RESULTS: No statistically significant differences were observed in the numbers of keratinocytes, yeast, bacteria, or neutrophils among the 4 staining methods (P > .05), although significant interobserver differences were found. CONCLUSION: We conclude that heat fixation does not improve the quality of ceruminous ear swab samples for cytologic evaluation, and propose a 1-step dip in the blue reagent alone as a rapid method of staining samples from canine ear canals.
Arcanobacterium pyogenes is a normal inhabitant of the mucous membranes of domestic animals, such as cattle, sheep, swine, and goats. It is also an opportunistic pathogen in these animals, where it causes a variety of purulent infections involving the skin, joints, and visceral organs. Two recent cases of isolation of A. pyogenes from companion animals are reported. In the first case, a cat presented with a chronic otitis externa, from which A. pyogenes was isolated in pure culture. The second case involved a dog with a urinary tract infection, where A. pyogenes was isolated from urine as the predominant bacterial species. In both cases, the A. pyogenes isolates were presumptively identified by macrobiochemical tests, and then their identities were confirmed by polymerase chain reaction analysis and 16S rRNA gene sequencing.
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Bilophila wadsworthia is an obligately anaerobic, gram-negative rod, which was first described in 1989. The natural habitat of this species seems to be the lower intestinal tract where it was recovered from about 60% of the persons investigated. Bilophila wadsworthia is mainly associated with intra-abdominal infections, but the species was also isolated as part of aerobic-anaerobic mixed infections at various extra-abdominal sites. Otological infections due to Bilophila wadsworthia have as yet not been described. In the present paper, we report a case of a patient with postoperative otitis externa following stapedectomy, probably caused by the anaerobes Bacteroides fragilis and Bilophila wadsworthia.
A 69-year-old man presented with a three-month history of otalgia and tenderness of the right ear and a one-week history of a painful right parotid swelling. Examination revealed granulation tissue in the right ear canal with normal looking tympanic membranes and a parotid abscess. Repeated biopsies from the ear canal and parotid showed non-specific inflammation. Repeated cultures from both areas grew Ps. aeruginosa. The patient's condition improved following three weeks of intensive treatment for malignant otitis externa only to relapse five weeks after the end of treatment. He received a second course, only to improve temporarily. He developed a right facial nerve palsy five weeks after he was first seen, followed four months later by palsies of all cranial nerves except the olfactory, before dying, seven months after his first appointment. The radiological, histological and post-mortem findings are discussed.
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