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.

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.

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.

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.

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.

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.

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.

Oxythiamine improves antifungal activity of ketoconazole evaluated in canine Malassezia pachydermatis strains.

BACKGROUND: Malassezia pachydermatis is an opportunistic yeast involved in skin and ear canal infections of dogs and cats. Reports suggest that strains of M. pachydermatis resistant to commonly used antifungal agents may be emerging. Therefore, new therapeutic strategies should be explored. OBJECTIVES: The synergistic effect of oxythiamine (OT) and ketoconazole (KTC) was analysed using a reference strain and field isolates (n = 66) of M. pachydermatis. Hydrogel formulations containing these components also were evaluated. METHODS AND MATERIALS: The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of OT, KTC and their mixtures were determined by a broth macrodilution method. The antifungal effects of hydrogel formulations were determined by a plate diffusion method. RESULTS: The MIC and MFC values of OT were in the range 0.08 × 103 to 10 × 103  mg/L. All M. pachydermatis strains showed higher susceptibility to KTC (MICs and MFCs in the range 0.04-0.32 mg/L). Formulations that combined OT and KTC showed a synergistic effect for all tested isolates (n = 66). Hydrogels that contained OT at a concentration of 10 × 103 or 20 × 103  mg/L and KTC at the concentration of 0.1 × 103  mg/L showed a stronger effect than a commercially available product with KTC alone (20 × 103  mg/L). CONCLUSIONS AND CLINICAL IMPORTANCE: Synergy of these drugs may allow for successful topical treatment which utilizes lower doses of KTC without changing its therapeutic effectiveness. Hydrogel formulations proved to be attractive drug carriers for potential topical use.

[In vivo-efficacy of an ear medication using gelatin powder as a vehicle for the therapy of canine otitis externa]. / In-vivo-Wirksamkeit eines Ohrmedikaments mit Gelatinepulver als Wirkstoffträger bei der Therapie kaniner Otitis externa.

OBJECTIVE: Otitis externa is normally treated with daily topical medication. Longer application intervals may be useful to facilitate therapy. In this study, the in vivo efficacy of a gel preparation containing marbofloxacin, dexamethasone and enilconazole was compared to that of a commercial otologic agent containing marbofloxacin, dexamethasone and clotrimazole based on clinical signs, ear cytology and bacterial/fungal cultures. MATERIAL AND METHODS: A gel preparation (group A) or a registered otologic agent (group B), respectively, was applied to 41 dogs. A total of 50 ears (25 per group) were analysed. The gel preparation was administered on days 0 and 5; the combination preparation was administered daily according to the manufacturer's recommendations. Dogs were reevaluated clinically and cytologically after 5 and 10 days. Initially and after 10 days, ear swabs were taken for bacterial and fungal cultures. RESULTS: No significant clinical or cytological differences were found between the groups. Significantly more isolates resistant to marbofloxacin were identified in group A after 10 days, although >98% of marbofloxacin was still detectable in vitro after 15 days. CONCLUSION: The clinical and cytological efficacy of a gel containing defined active agents applied twice 5 days apart was comparable to that of an authorised otologic agent applied once daily. There appears to be an increased risk with the gel in that a resistance to fluoroquinolones develops. Local adverse effects are also possible. CLINICAL RELEVANCE: A gelatine preparation containing active agents may be an alternative to daily topical therapy of canine otitis externa. The development of resistances is possible.

Traditional Mediterranean plants: characterization and use of an essential oils mixture to treat Malassezia otitis externa in atopic dogs.

Several plants extracts from Mediterranean countries are traditionally employed in skin troubles both in humans and in animals. Malassezia pachydermatis is a lipophylic yeast responsible for otitis externa and dermatitis in dogs and for cutaneous and systemic disease in humans. Five mixtures of essential oils obtained from Mediterranean plants (Citrus paradisi, Salvia sclarea, Ocimum basilicum, Rosmarinus officinalis, Citrus limon, Anthemis nobilis, Lavandula hybrida and Thymus vulgaris) provided with antifungal and/or anti-inflammatory action assayed in vitro, were tested in vivo versus M. pachydermatis to treat once daily for 2 weeks 25 atopic dogs with Malassezia otitis externa. Mixture composed by C. limon 1%, S. sclarea 0,5%, R. officinalis 1%, A. nobilis 0,5% yielded excellent results in all treated dogs. Despite of clinical resolution after all treatments the number of blastospores did not decrease. This study confirms recent findings suggesting a multifactorial alternative approach for the management of canine Malassezia otitis.

In vitro antimicrobial activity of a gel containing antimicrobial peptide AMP2041, chlorhexidine digluconate and Tris-EDTA on clinical isolates of Pseudomonas aeruginosa from canine otitis.

BACKGROUND: Pseudomonas aeruginosa (PA) may cause suppurative otitis externa with severe inflammation and ulceration in dogs. Multidrug resistance is commonly reported for this organism, creating a difficult therapeutic challenge. OBJECTIVE: The aim of this study was to evaluate the in vitro antimicrobial activity of a gel containing 0.5 µg/mL of antimicrobial peptide AMP2041, 0.07% chlorhexidine digluconate (CLX), 0.4% Tris and 0.1% EDTA on 30 clinical isolates of PA from canine otitis externa. MATERIALS AND METHODS: Antimicrobial activity was evaluated through minimal bactericidal concentration (MBC). Standardized bacterial suspensions were incubated with different concentrations of the gel at 37°C for 30 min and plated for colony forming unit (CFU) counts. Time-to-kill kinetics were evaluated with the undiluted product and at MBC for each PA strain at 30 s, 1, 5, 10, 15, 30 min, 24 and 48 h. RESULTS: The MBC was 1:64 for two of 30 strains, 1:128 for 15 of 30 strains and 1:256 for 13 of 30 strains. The geometric mean was 1:165, equivalent to a concentration of 0.003 µg/mL AMP2041 + 0.0004% CLX + 0.0024%Tris + 0.0006% EDTA. Time-to-kill assays with the undiluted product showed complete bactericidal effect within 30 s for all isolates, whereas at the MBC this effect was reached within 5 min for 20 of 30 isolates and within 30 min for all isolates. Bactericidal activity was maintained after 48 h for all isolates. CONCLUSION: This gel has shown rapid, complete and long-lasting activity against a panel of 30 PA isolates from cases of canine otitis externa.

Antibacterial effect of N-acetylcysteine on common canine otitis externa isolates.

BACKGROUND: N-Acetylcysteine (NAC) has the potential to be a useful therapeutic agent for the treatment of otitis externa due to its antimicrobial and mucolytic properties, as well as its ability to disrupt bacterial biofilm. HYPOTHESIS/OBJECTIVES: To determine the antibacterial activity of NAC against common bacterial isolates associated with canine otitis externa. ANIMALS: Twenty two isolates from canine clinical cases of otitis externa were identified and tested, including five Staphylococcus pseudintermedius, six Pseudomonas aeruginosa, five Corynebacterium spp. and six ß-haemolytic Streptococcus spp. isolates. METHODS: Each isolate was grown on blood agar for 24 h and transferred to Mueller Hinton Broth (MHB) to achieve a final concentration of 5 × 10(5)  CFU/mL. NAC was diluted in MHB to a starting concentration of 160 mg/mL and serial two-fold microdilution assays were performed in triplicate with negative controls for all isolates tested. Concentrations of NAC tested ranged from 0.125 to 80 mg/mL. A 50 µL volume of bacterial suspension was used to inoculate each well. RESULTS: The minimum inhibitory concentration (MIC) of NAC for all isolates tested ranged from 5 to 20 mg/mL. CONCLUSIONS AND CLINICAL RELEVANCE: N-Acetylcysteine inhibits clinically relevant and drug resistant bacteria in vitro, and has potential for use as a novel agent for treatment of otitis externa.

Efficacy of medical grade honey in the management of canine otitis externa - a pilot study.

BACKGROUND: The high prevalence of antimicrobial resistance within otic pathogens has created a need for alternative therapies of otitis externa (OE). Evidence suggests that medical grade honey (MGH) may be effective against drug-resistant pathogens. HYPOTHESIS/OBJECTIVES: The efficacy of a commercial MGH compound was assessed in an open clinical trial. We hypothesized that it would be an effective alternative to conventional treatments. ANIMALS: Client-owned dogs (n = 15) with a confirmed diagnosis of infectious OE were enrolled in this pilot study. METHODS: Dogs were prescribed MGH (1 mL daily per ear) until cure was achieved or for a maximum of 21 d. Evaluation was based on weekly clinical scores, cytological progression and owner assessments of pruritus. Swab samples were submitted for culture and susceptibility testing. MGH was tested for biocidal activity against the bacterial isolates. RESULTS: Medical grade honey promoted rapid clinical progress, with 70% of dogs achieving clinical cure between days 7 and 14 and over 90% having resolved by Day 21. There was a decrease in clinical scores throughout the duration of the trial (P < 0.001) and owner-assessed pruritus also decreased significantly (P < 0.05). In vitro assays of the biocidal activity of MGH showed activity against all bacterial isolates, including meticillin-resistant strains of Staphylococcus pseudintermedius (MRSP) and other species of drug-resistant bacteria. CONCLUSION AND CLINICAL IMPORTANCE: Medical grade honey was successful in both clinical and laboratory settings, thus demonstrating its potential of becoming an alternative treatment for canine OE.

Clinical evaluation of an antiinflammatory and antioxidant diet effect in 30 dogs affected by chronic otitis externa: preliminary results.

The aim of this evaluation study was to assess the possible role of a specific nutraceutical diet in relieving main clinical symptoms of chronic bilateral otitis externa (occlusion of ear canal, erythema, discharge quantity, and odor) in 30 adult dogs. Thirty dogs of different breeds (mean age ± SEM; 6.03 ± 0.15 years and mean weight ± SEM; 32.01 ± 1.17 Kg; 53.3% males, 46.6% females) with evident chronic clinical otitis symptoms were equally divided and randomly assigned to receive either the nutraceutical diet (ND group) or a standard diet (SD group) over a period of 90 days. In all cases a topical pharmacological treatment was given. The nutraceutical diet, also endowed with anti-inflammatory and antioxidant activities, significantly decreased the mean score intensity of all symptoms after 90 days of intervention (P < 0.0001) with the exception of Malassezia pachydermatis infection which was only slightly reduced. Our investigation is one of the few evidence-based results where a commercial nutraceutical diet has been proven effective, in combination with drugs, in relieving otitis externa-related symptoms. This study opens new insights into otitis externa clinical management providing evidence of efficacy of a combined therapy with drugs and a specific nutraceutical diet.

Comparison of lipid profiles of Malassezia pachydermatis strains isolated from dogs with otitis externa and without clinical symptoms of disease.

Malassezia pachydermatis can cause infections of the skin and mucous membranes, especially in animals. It becomes a problem also in medicine. It is considered that metabolic disorders as well as hormonal and immunological status of the host promote diseases caused by M. pachydermatis. Here we consider whether specific features of fungi could also favour infections. We checked whether there are differences in lipid profiles between strains obtained from dogs with otitis externa and strains obtained from healthy dogs. Lipid profiles were determined using thin layer chromatography and gas chromatography-mass spectrometry. All analyses were carried out on 32 strains derived from dogs with otitis externa and 31 strains isolated from dogs without symptoms of disease. The results show that strains isolated from dogs without symptoms of otitis externa are characterised by a higher content of fatty acids. They contain significantly more behenic and lignoceric acids on medium without addition of lipids, and more oleic acid and total monounsaturated fatty acids on medium with lipids supplementation. These strains have also a higher content of esters of ergosterol and triglycerides. Data obtained show differences which may be specific features of M. pachydermatis-specific strains related to the ability of infection, which could be not directly related of the host condition.

Identification and antibiotic susceptibility of bacterial isolates from dogs with otitis externa in Australia.

OBJECTIVE: To identify and quantify the five most frequently isolated significant bacterial microorganisms, and their antibiotic susceptibility, from bacterial cultures of samples taken from the ears of dogs with otitis externa. METHODS: Bacterial culture and susceptibility testing data for ear swabs from dogs with presumed otitis externa were collated and evaluated. RESULTS: The five most frequently isolated microorganisms were: Pseudomonas aeruginosa, Staphylococcus pseudintermedius, Proteus sp., beta-haemolytic streptococci and Escherichia coli. Susceptibility to gentamicin was very high for most isolates, whereas for polymyxin B, high levels of resistance were seen. Beta-haemolytic streptococci had high levels of resistance to all of the antibiotics tested. CONCLUSIONS: This study provides veterinarians with Australian data to assist in cytological interpretation and initial empirical therapy of canine otitis externa.

Bacterial contamination of commercial ear cleaners following routine home use.

Ear cleaning solutions are designed for repeated use, which raises the possibility for bacterial contamination leading to recurrent or persistent infectious otitis. The purpose of this study was to investigate the prevalence of bacterial contamination of commercial ear cleaners following routine home use in dogs and to describe the characteristics that are associated with contamination. Used ear cleaner bottles and information regarding their use were obtained from canine owners visiting veterinary dermatologists. Both the bottle applicator tips and the solution contents were cultured for aerobic bacteria. Bacterial contamination was present on 10% of the bottle tips and in 2% of the solutions. Isolated bacteria included Staphylococcus pseudintermedius, Bacillus spp., coagulase-negative Staphylococcus spp., Micrococcus spp. and Burkholderia cepacia. The contamination rate was significantly higher on the applicator tips than in the solutions (P = 0.0076). The applicator tip contamination rate was significantly higher in expired samples (17%) than in-date samples (4%; P = 0.0277). The bottle sizes were significantly larger for the samples with contaminated applicator tips compared with noncontaminated tips (P = 0.0455). The contamination rate was significantly higher when Tris-EDTA was an ingredient. Cleanliness of the bottle, contact with the ear canal and infection status of the ear at time of culture had no bearing on the contamination rate. In summary, with routine home use of commercial ear cleaners, pathogenic bacterial contamination is of minor concern. This concern may increase when expired products or larger bottles of ear cleaner are used and when Tris-EDTA is an ingredient.