Antimicrobial effect of chamomile-containing over-the-counter ear and eye drops.

Chamomile (Matricaria chamomilla) is a plant with known antimicrobial, anti-inflammatory, and analgesic properties. Homeopathic drops containing chamomile extract are often used for ear pain and chronic ear infections. We aimed to evaluate the antimicrobial effect of over-the-counter eardrops containing chamomile against organisms causing bacterial conjunctivitis and otitis externa. Liquid cultures of Streptococcus aureus and Pseudomonas aeruginosa were exposed to increasing concentrations of eardrops containing chamomile extract. Liquid cultures of S. aureus and Streptococcus pneumoniae were exposed to increasing concentrations of chamomile eye drops for 5, 10, 15, and 45 min. Colony forming units (CFUs) were assessed after 18 h. Viability assays for these organisms were performed using the resazurin microdilution assay. We observed a reduction in the number of P. aeruginosa CFUs when the bacteria were exposed to any of the three concentrations of the chamomile drops as early as 5 min, with maximal reduction upon exposure to the 30% concentration at 45 min. Reduction in S. aureus CFUs, on the other hand, was observed for all three concentrations as maximal in the 5 min of exposure. We observed a marked reduction in the number of S. aureus CFUs upon exposure to any of the three preparations of chamomile-containing eye drops, which was almost immediate at 10% concentration. Streptococcus pneumoniae reduction happened at 5 min and continued through the 45-min observation period for all three concentrations. Our findings suggest that over-the-counter ear drops containing chamomile extract could potentially be used as a non-prescription treatment for mild cases of otitis externa and bacterial conjunctivitis.

Evaluation of in vitro activity of herbal formula Di Er You and herb Coptis against bacteria isolated from dogs with otitis externa.

OBJECTIVE: To determine the in vitro activity of the herbal formula Di Er You (DEY) and the single-herb Coptis against bacteria cultured from dogs with otitis externa. ANIMALS: 32 client-owned dogs diagnosed with otitis externa. METHODS: A sample of otic debris from each patient was collected and plated onto a fresh Sheep's Blood Agar plate in the hospital. After bacterial growth was confirmed, 4 wells were created, numbered randomly, and treated with saline (placebo), DEY, Coptis, and Zymox Otic Enzymatic Solution with 1% Hydrocortisone (Zymox). After 24 hours of incubation, the diameter of the zone of inhibition (dZOI) of each treatment was measured and recorded, and compared among treatments. A sample of the bacterial colonies grown was submitted to an outside lab for bacterial identification. RESULTS: The mean ± SD dZOI values for saline, DEY, Coptis, and Zymox treated wells were 0.25 ± 1.41, 12.47 ± 3.92, 14.25 ± 7.12, and 3.22 ± 5.12, respectively. Post hoc multiple comparisons test revealed that (1) saline-treated wells had significantly smaller dZOI values than the other 3 groups (all P < .001), (2) Zymox treated wells had significantly smaller dZOI values than either herbal treated groups (both P < .001), and (3) DEY treated wells had significantly smaller dZOI values than those treated with Coptis (P = .0042). CLINICAL RELEVANCE: The results from this in vitro study suggested that both DEY and Coptis could be effective treatments in inhibiting the growth of bacteria in dogs with otitis externa. Prospective randomized controlled clinical trials are warranted to confirm these findings.

Management and Clinical Outcomes of 37 Patients with Necrotizing Otitis Externa: Retrospective Review of a Standardized 6-Week Treatment Pathway.

BACKGROUND: Necrotizing otitis externa is an invasive infection, affecting older patients, with significant associated morbidity. Despite this, there are no randomized controlled trials that address management, and therefore, treatment approaches may vary considerably. We describe the management and outcomes of 37 patients managed using a multidisciplinary treatment pathway for necrotizing otitis externa over a 5-year period. The pathway is based on a standardized antibiotic regime of 3 weeks of intravenous ceftazidime plus oral ciprofloxacin, followed by a further 3 weeks of ciprofloxacin. METHODS: This is a retrospective review of all patients diagnosed with necrotizing otitis externa since the introduction of our pathway in 2016. We include data on patient demographics, comorbidities, microbiology, length of stay, and length of antimicrobial treatment. Outcome data, including mortality, relapse and treatment failure, and adverse effects of treatment, are presented. RESULTS: The median age of our patients was 82 years. About 54% of patients had diabetes mellitus or another cause of immunocompromise. Pseudomonas aeruginosa was isolated in 68%. The median duration of inpatient stay was 9 days, and median treatment duration was 6 weeks. Of 37 patients, 32 were cured (86%), and of the remaining 5 patients, there were 2 mortalities unrelated to necrotizing otitis externa and 3 patients with recurrent infections due to anatomical abnormalities. CONCLUSION: We note favorable treatment outcomes when using a standardized multidisciplinary pathway and a 6-week course of antibiotic therapy.

Homeopathy treatment of Malassezia Pachydermatis in vitro

A common clinical occurrence in dogs is otitis externa caused by excessive growth of yeasts Malassezia pachydermatis, which can become chronic after wrong treatments, in which microbial resistance can occur. Homeopathic remedies can be considered a successful alternative, selecting the medicine through the similitude principle. Herein, 50 µL of a 1:1000 dilution of Malassezia pachydermatis suspension at 0.5 McFarland scale was used to seed the yeast into Sabouraud dextrose agar plates using a Drigalski spreader to proceed with colony unit counting. Before being seeded, the yeast suspensions were treated with 1% of different homeopathic treatments previously selected from a pilot study, which means Sulphur 6cH, Dolichos pruriens 6cH, and Kali carbonicum 6cH, being water, and succussed water used as controls. For comparison, a set of Sabouraud dextrose agar plates containing 1% Tween 80 was seeded in parallel. The treatments were made blind and evaluated in triplicate. Contaminated cultures were withdrawn. The number of colonies per plate was assessed, and smears were made from the cultures to classify yeast growth according to cytomorphology on ImageJ®software. The preliminary results show no significant effect of all tested medicines compared to the controls. High data variability was also observed, mainly in those cultures whose medium was prepared with Twin 80. In conclusion, at this point of the study, no evidence of the effects of the studied medicines on Malassezia pachydermatis growth in vitro could be identified. The analysis of cytomorphology is still in course.

In vitro and in vivo evaluation of a new phytotherapic blend to treat acute externa otitis in dogs.

Canine otitis externa is frequently encountered in veterinary practice, caused by primary factors with bacteria and yeast overgrowth acting as secondary and perpetuating factors. The pharmacological support includes anti-inflammatory, antimicrobials, and antimycotic drugs, but therapeutic failure and antimicrobial resistance are leading to alternative strategies based on phytotherapic products. This study aimed to evaluate an essential oil blend (Otogen® ) to treat otitis externa in dogs. The experimental design was divided in: (a) an in vitro approach, based on the European Normative UNI EN 1275:2006, to assess the efficacy of the product against the most frequently isolated microorganisms during otitis externa. (b) an in vivo part, 12 owned dogs presenting with acute otitis externa were enrolled. A significant growth reduction (>99.9%) of Malassezia pachydermatis and Candida albicans after 15 min of contact and Pseudomonas aeruginosa after 1 h of incubation was recorded. For Staphylococcus pseudintermedius, 50% of growth reduction were appreciated after 15 min. Results obtained in vivo after 7 days of blend administration, noted a significant improvement of all the considered parameters (most important were head shaking, erythema, and scraping). The results obtained may support the usefulness of the tested phytotherapic blend to manage acute otitis externa in dogs.

Standardised treatment protocol for necrotizing otitis externa: retrospective case series and systematic literature review.

OBJECTIVES: There is currently no consensus on the most effective treatment protocol for necrotizing otitis externa (NOE). This article aims to produce a NOE treatment protocol from the literature and clinical experience. METHODS: A total of 26 case series from the literature were reviewed in combination with a retrospective case series of inpatients from Hull University Teaching Hospitals NHS Trust from 2013-2018. Over 5 years, 40 patients were identified, with only 29 being analysed due to unavailable or incomplete case notes. RESULTS: In the literature review, the most common bacterial species causing NOE was Pseudomonas aeruginosa. Resistance to ciprofloxacin was prevalent, however multidrug resistance was rare. Ciprofloxacin and ceftazidime were the most widely used antibiotics. No ceftazidime resistance was reported in the literature or in our cohort. The average age of the patients in our cohort was 80 years. Moreover, 62% had either diabetes mellitus or were immunosuppressed. One patient died directly due to NOE-related sepsis. Intravenous ceftazidime monotherapy was mostly used. The duration of treatment was 6-7 weeks, with no relapses documented. CONCLUSION: Ceftazidime monotherapy was an effective empirical treatment in our cohort, and a total duration of 6-7 weeks of antibiotics was sufficient. We have created a standardised treatment protocol based on our findings that will need to be validated in a larger cohort of patients.

[Modern aspects of inflammatory external ear diseases treatment]. / Sovremennye aspekty lecheniya vospalitel'nykh zabolevanii naruzhnogo ukha.

The article deals with the problem of inflammatory diseases of the external ear. A review of pruritic dermatoses of the external auditory canal was carried out. It has been shown that in chronic dermatoses, the contamination of the skin with bacterial and fungal pathogens significantly increases, which leads to a high risk of developing secondary infectious pathological processes. Treatment of dermatological inflammatory ear diseases includes careful daily hygiene of the external auditory canal and pharmacotherapy, a key aspect of which is the use of topical etiotropic, anti-inflammatory, and symptomatic drugs. The advantage of the combined drug candiderm is described, which, thanks to the unique combination of beclomethasone, gentamicin and clotrimazole in the composition, effectively relieves the symptoms of external ear dermatoses.

Effect of an anti-inflammatory pomegranate otic treatment on the clinical evolution and microbiota profile of dogs with otitis externa.

BACKGROUND: Canine otitis externa (OE) is a common disease characterised by inflammation of the epithelial tissue of the external ear canal. Secondary infections are frequent, and Malassezia pachydermatis and Staphylococcus pseudintermedius are routinely isolated and treated with antifungal and antibiotic compounds. HYPOTHESIS/OBJECTIVES: To analyse the otitis ear microbiome before and after a treatment with prednisolone plus pomegranate or antimicrobial drugs ANIMALS: 15 dogs with nonpurulent OE. METHODS AND MATERIALS: A 30 day, double-blinded, multicentre, randomized and controlled parallel-group (1:1) trial was conducted in 15 dogs with nonpurulent OE, following two different topical treatments (prednisolone plus pomegranate versus prednisolone plus antibiotic and antifungal drugs). On days (D)0, D15 and D30, serum and skin otic samples were collected, and clinical examination and microbiome analysis (bacteria and fungi) were performed. Results were compared with validated otitis clinical scores to assess the effectiveness of both treatments. RESULTS: Nine bacterial and four fungal families were detected during the three time-points tested. An increase in fungal diversity (Shannon index) and composition was the most significant change observed after both treatments. At treatment D15 and D30, the reduction in clinical signs was statistically significant in both treatment groups (P ≤ 0.05). Prednisolone plus pomegranate cleanser treatment was able to control the clinical signs of otitis as well as the bacterial and fungal overgrowth. CONCLUSIONS AND CLINICAL IMPORTANCE: Mild otitis cases associated with microbial overgrowth may be managed with topical antiseptic and anti-inflammatory agents without the need for antibiotic and/or antifungal compounds.

Preliminary evaluation of two commercial ear solutions in the treatment of canine otitis externa.

OBJECTIVES: Preliminary evaluation of the efficacy of two commercial ear solutions composed of (1) chlorhexidine-Tris-ethylenediaminetetraacetic acid (EDTA) or (2) medical grade honey, for the treatment of otitis externa in dogs. MATERIALS AND METHODS: Dogs affected with otitis externa housed in an animal shelter were eligible for inclusion. Treatment was applied daily for 10 days and effect was measured by otitis clinical scores and microbiological counts. One of the treatments was applied to affected left ears, while the other was applied to affected right ears. RESULTS: A total of 24 ears from 13 dogs were included in the study. During the treatment period, with both treatments it was observed an improvement in clinical scores and a decrease in microbiological counts. At the end of the study 22 of 24 ears were deemed to have mild (4 ears), or no (18 ears) pain, with only two ears still showing pruritus. CLINICAL SIGNIFICANCE: The application of ear solutions composed of chlorhexidine-Tris-EDTA or medical grade honey, in the absence of antimicrobial treatment, might be effective for the control of clinical signs and microbial colonisation in dogs with otitis externa. Additional randomised studies on clinical patients are required to validate these findings.

Aspergillus necrotizing otitis externa with temporomandibulozygomatic involvement.

INTRODUCTION: Aspergillus necrotizing otitis externa (NOE) is a rare disease, often associated with delayed diagnosis, the management of which is poorly defined. SUMMARY: The authors report a case of Aspergillus flavus necrotizing otitis externa with temporomandibular arthritis and temporozygomatic osteomyelitis with Staphylococcal coinfection in a diabetic patient. The diagnosis and discontinuation of treatment were guided by PET-CT scan. A favourable course without sequelae was observed after repeated surgical curettage and 3 months of antifungal therapy. DISCUSSION: Aspergillus flavus is the agent most commonly incriminated in NOE. Indirect diagnostic tests (serology) may be negative. The diagnosis is based on imaging-guided surgical biopsy with histological examination and standard and fungal microbiological culture. Treatment requires a combination of surgery and antifungal therapy. The duration of antifungal therapy is poorly defined and discontinuation of therapy can be guided by PET-CT scan.

Management of otitis externa with an led-illuminated gel: a randomized controlled clinical trial in dogs.

BACKGROUND: Canine otitis externa is a painful condition which can be challenging to treat due to difficulties in the administration of otic medication. This can be due to lack of owner compliance in the application of ear drops or due to the resentment that some dogs demonstrate when attempts are made to administer topical medication into a sensitive ear canal. The aim of the study was to assess the efficacy of a topical LED-illuminated gel (LIG) in canine otitis externa in comparison to standard of care therapy. Dogs with spontaneous otitis externa were randomly allocated in three groups: groups QW received LIG once weekly; BW received LIG twice weekly; group C received enrofloxacin and silver sulfadiazine twice daily. LIG consists of a topical application of a gel containing chromophores that, when illuminated by a LED lamp, re-emit fluorescent light which can stimulate physiological responses, promoting healing and controlling bacteria. The evaluation protocol (T0 to T5) considered clinical assessment (OTIS-3-index-scoring-system; pruritus-severity-scale; pain-severity-score; aural temperature), cytological scoring system, quali-quantitative bacteriologic assessment. RESULTS: All groups (QW, n = 21; BW, n = 23; C, n = 20) showed improvement during the study (QW: P < 0.02 for cytological and pain scores, P < 0.003 for bacteriologic assessment, P < 10- 4 for pruritus, total OTIS-3 and temperature assessments; BW: P < 10- 4 for all clinical, cytological and bacteriologic assessments; C: P < 0.02 for all clinical and cytological assessments, P < 10- 4 for bacteriologic assessment). The highest clinical score reduction occurred in Group BW (P < 0.014 in T3; P < 0.001 in T4 and P < 10- 4 in T5). BW reached the clinically relevant effect level at T3 (- 3.26 ± 1.21 levels), QW reached it at T4 (- 3.24 ± 0.99), C did not reach it. No differences between groups were seen in the reduction of CFU/mL (T0-T5). CONCLUSIONS: All treatment groups showed a positive clinical effect. LIG administered twice-a-week was the most favourable protocol of the study. LIG may be considered beneficial in the management of canine otitis externa; it seems to be effective in controlling the clinical condition, including the signs of inflammation and local pain, the bacterial growth, and it may help increasing treatment compliance.

Meta-analysis does not support routine traditional nuclear medicine studies for malignant otitis.

OBJECTIVES: The role of traditional nuclear medicine studies in the management of malignant otitis externa (MOE) is unclear and there are ongoing debates regarding their diagnostic value. The authors perform a systematic review and meta-analysis to assess the sensitivity and specificity of traditional nuclear medicine studies in the diagnosis of MOE. METHODS: In accordance with PRISMA guidelines, a query of the Medline, Embase, Web of Science, and Cochrane databases was undertaken. The primary outcomes of interest were the sensitivity and specificity of traditional nuclear medicine studies to detect MOE. RESULTS: Of the initial 1317 hits from the four databases, 20 articles with a combined 608 patients were ultimately included in the review. The pooled sensitivities for Technetium-99 and Gallium-67 were 85.1% (95% CI, 72.0-98.1%) and 71.2% (95% CI, 55.1-87.3%) respectively. The available evidence suggested poor specificity of these modalities, but was insufficient for meta-analysis. Neither modality was shown to be effective in the assessment of disease resolution. CONCLUSION: The sensitivities of Technetium-99 and Gallium-67 to detect MOE are less favorable than was initially thought. Given this finding and their poor specificity, lack of anatomic resolution, unproven ability to detect disease resolution and variable availability, this review does not support the routine use of these studies in the management of MOE. LEVEL OF EVIDENCE: N/A Laryngoscope, 130:1812-1816, 2020.

Antimicrobial activity of thyme oil, oregano oil, thymol and carvacrol against sensitive and resistant microbial isolates from dogs with otitis externa.

BACKGROUND: Multidrug-resistant pathogens present a major global challenge in antimicrobial therapy and frequently complicate otitis externa in dogs. HYPOTHESIS/OBJECTIVES: In vitro efficacy of oregano oil, thyme oil and their main phenolic constituents against bacterial and fungal isolates associated with canine otitis externa were investigated. It was hypothesized that the main phenolic components would have greater antimicrobial activity compared to the relative essential oil. METHODS AND MATERIALS: Antimicrobial susceptibility testing was performed using broth microdilution with spot-plating technique to determine minimum inhibitory and bactericidal/fungicidal concentrations (MICs, MBCs and MFCs). A time-kill kinetics assay was performed to confirm the bactericidal and fungicidal activity of the oils and their phenolic constituents. One hundred bacterial and fungal isolates, including meticillin-susceptible Staphylococcus pseudintermedius (n = 10), meticillin-resistant S. pseudintermedius (n = 10), ß-haemolytic Streptococcus spp. (n = 20), Pseudomonas aeruginosa (n = 20; including 10 isolates resistant to one or two antimicrobials), Proteus mirabilis (n = 20) and Malassezia pachydermatis (n = 20) from dogs with otitis externa were used. RESULTS: Oregano oil, thyme oil, carvacrol and thymol exhibited antibacterial activity against all bacterial and fungal isolates tested. MIC90 values ranged from 0.015 to 0.03% (146-292 µg/mL) for the Gram-positive bacteria and P. mirabilis. For P. aeruginosa and M. pachydermatis, MIC90 values ranged from 0.09 to 0.25% (800-2,292 µg/mL). CONCLUSIONS AND CLINICAL SIGNIFICANCE: Oregano oil, thyme oil, carvacrol and thymol showed good in vitro bactericidal and fungicidal activity against 100 isolates from dogs with otitis externa, including some highly drug-resistant isolates. These essential oils and their main phenolic constituents have the potential to be further investigated in vivo for the treatment of canine otitis externa.

Malignant (necrotizing) externa otitis: the experience of a single hyperbaric centre.

INTRODUCTION: Malignant otitis externa (MOE) is a potentially life-threatening infection of the soft tissues of the external ear, quickly spreading to involve the periosteum and bone of the skull base. Treatment includes antibiotics and eventually surgery. Hyperbaric oxygen treatment (HBOT) has been proposed as an adjunctive therapy. However, in the tenth consensus conference, this disease was considered as a non-indication for HBOT. The aim of this study was to evaluate the effectiveness of HBOT in MOE treatment. METHODS: Retrospective and observational study was conducted of patients with MOE treated in our centre. Staging of the disease was made according to the clinicopathological classification system. RESULTS: From March 1998 to November 2016, 16 patients were referred. 6% patients were on stage 1 of the disease at the time they were referred, 20% in stage 2, 7% in stage 3a, 13% in stage 3b and 53% in stage 4. Seven (43.75%) patients had VII nerve palsy and three (18.75%) patients had multiple nerve palsy. Average length of symptoms of disease was 5 months (maximum 11 months). Average number of sessions was 33 and the length of hospitalization prior to HBOT (median 90 days) was significantly longer than the time between beginning HBOT and cure (p = 0.028, Wilcoxon signed rank test). There were no fatalities due to MOE and all patients were considered free of disease after HBOT. CONCLUSION: HBOT was well tolerated and revealed to be a helpful adjuvant treatment in MOE. According to our data, HBOT should be considered for patients who failed conventional treatments and in severe cases.

Carriage of Staphylococcus schleiferi from canine otitis externa: antimicrobial resistance profiles and virulence factors associated with skin infection.

The recent emergence of Staphylococcus schleiferi in dogs with otitis externa or skin and soft tissue infections has become a significant zoonotic issues. In the current study, we investigated 1) the carriage rates of S. schleiferi among major staphylococci in healthy dogs and dogs with otitis externa, 2) antibiotic susceptibility profiles of S. schleiferi, particularly methicillin resistance (MR), and 3) virulence factors associated with skin and soft tissue infections such as ability to form biofilm, resistance to cationic antimicrobial peptides (CAMPs), and carriage of staphylococcal enterotoxin genes. Among the 21 S. schleiferi isolates, 5 isolates (24%) were determined to be methicillin-resistant (MRSS). Staphylococcal cassette chromosome mec (SCCmec) typing revealed the presence of SCCmec type V in 4 MRSS isolates and type VII in one MRSS. Higher levels of antibiotic resistance, especially multidrug resistance, were observed in MRSS isolates compared to the methicillin-susceptible S. schleiferi (MSSS) isolates. In addition, MRSS isolates exhibited enhanced ability to form biofilm under static condition and all the 5 MRSS isolates carried three or more enterotoxin genes. However, there were no significant differences in resistance to CAMPs between MRSS and MSSS isolates. These findings suggest that coagulase-negative S. schleiferi is becoming more prevalent in canine otitis externa cases. Our results also highlight the presence of multidrug-resistant MRSS isolates with enhanced biofilm production and carriage of multiple enterotoxins.

OTO-201 for the Treatment of Acute Otitis Externa: Results from a Phase 3 Randomized Clinical Study.

OBJECTIVES: OTO-201 is a ciprofloxacin otic suspension previously approved by the US Food and Drug Administration to treat children with bilateral otitis media with effusion requiring tympanostomy tube placement. In this phase 3, double-blind, randomized, prospective, sham-controlled, multicenter study, a single dose of OTO-201 was administered to the external auditory canal in subjects with unilateral or bilateral acute otitis externa. METHODS: Two hundred sixty-two subjects, 3 to 83 years of age, were randomized, and 260 subjects were included in the intent-to-treat analysis population: OTO-201 (0.2 mL, 12 mg, n = 130) or sham (air injection, n = 130). The primary efficacy measure was clinical cure (CC) on day 8, judged by blinded assessor for erythema, edema, otorrhea, and tenderness. Subjects were monitored over 28 days for efficacy and safety. RESULTS: OTO-201 demonstrated a significant increase in CC compared with sham at day 8 (69.2% vs 46.1%, P < .001). Higher CC was also noted on day 4 ( P = .028), day 15 ( P < .001), and day 29 ( P < .001). A similar effect was observed in the pathogen-positive population. Single OTO-201 administration in the office setting was well tolerated by subjects. CONCLUSIONS: In this study in subjects with acute otitis externa, a single administration of 12 mg OTO-201 to the external auditory canal demonstrated a significantly higher proportion of subjects with CC and bacterial eradication compared with sham starting on day 4 and on all other observation days through day 29, with no safety or tolerability concerns identified. OTO-201 is the first agent in a randomized phase 3 study to demonstrate the efficacy and safety of a single-dose, health care professional-administered topical antibiotic for the treatment of acute otitis externa.

In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa.

BACKGROUND: An antibiotic adjuvant is a chemical substance used to modify or augment the effectiveness of primary antimicrobial agents against drug-resistant micro-organisms. Its use provides an alternative approach to address the global issue of antimicrobial resistance and enhance antimicrobial stewardship. HYPOTHESIS/OBJECTIVES: To determine the antimicrobial activity of a panel of potential antimicrobial adjuvants against common pathogens associated with canine otitis externa (OE). ANIMALS/ISOLATES: A number of type strains and clinical isolates (n = 110) from canine OE were tested including Staphylococcus pseudintermedius, ß-haemolytic Streptococcus spp., Pseudomonas aeruginosa, Proteus mirabilis and Malassezia pachydermatis. METHODS AND MATERIALS: Antimicrobial activities of monolaurin, monocaprin, N-acetylcysteine (NAC), polymyxin B nonapeptide, Tris-EDTA, Tris-HCL and disodium EDTA were tested using microdilution methodology according to CLSI guidelines. RESULTS: N-acetylcysteine, Tris-EDTA and disodium EDTA had antimicrobial activity against both type strains and otic pathogens. The other adjuvants tested had limited to no efficacy. NAC had a minimal inhibitory concentration (MIC) range of 2,500-10,000 µg/mL for the various organisms. Pseudomonas aeruginosa isolates were eight times more susceptible to disodium EDTA in the presence of Tris-HCL in comparison to disodium EDTA alone. Malassezia pachydermatis isolates were most susceptible to Tris-EDTA (MIC90  = 190/60 µg/mL) and disodium EDTA (MIC90  = 120 µg/mL). CONCLUSIONS AND CLINICAL RELEVANCE: N-acetylcysteine, Tris-EDTA and disodium EDTA have intrinsic antimicrobial activity and represent promising adjuvants that could be used to enhance the efficacy of existing antibiotics against Gram-negative and multidrug-resistant bacterial infections. These agents could be combined with other antimicrobial agents in a multimodal approach for mixed ear infections in dogs.

The significance of tissue biopsy for fungi in necrotizing otitis externa.

INTRODUCTION: The conventional treatment for necrotizing otitis externa (NOE) is prolonged anti-pseudomonas therapy, with surgical treatment in non-responsive patients. The aim of the present study is to describe the course of management of patients with non-responsive NOE undergoing hyperbaric oxygen therapy (HBOT), and to investigate the importance of tissue biopsy for fungi in this group of patients. MATERIALS AND METHODS: A retrospective study conducted between January 2010 and December 2013 at an Otolaryngology Head and Neck Surgery Department. Included were all 52 patients with NOE referred to our Medical Centre for further treatment including HBOT. RESULTS: Fifty-two consecutive patients, 29 men and 23 women, with a mean age of 70.6 years, were included in our study. Twenty seven (51.9%) underwent surgical debridement. No significant difference was found between the group having surgical intervention, and those who did not, with regard to sex, age, comorbidities, cranial nerve involvement or laboratory results. However, those who had surgical intervention had a statistically significant higher rate of fungal infection (P = 0.049). After completing 7 weeks of HBOT, a significantly lower WBC count was observed in the fungus-infected group (7000 vs 7.800, P = 0.03), and a tendency towards lower CRP levels in the fungus-infected group (16 vs 58, P = 0.087). CONCLUSION: Patients with NOE should have a comprehensive surgical intervention when delayed healing is observed, because proper fungal culturing might change the course of treatment and improve prognosis. LEVEL OF EVIDENCE: 4.