Ears, otitis and putting medication to the best use in the age of AMR (2023)

Overview

Join us for an informative webinar featuring renowned dermatology specialist Ariane Neuber, where she will share her expertise on the use of cytology in selecting the most effective medication to combat antimicrobial resistance. The webinar will cover the importance of identifying the causative agents of skin infections through cytology, and how this information can be used to make informed decisions about the appropriate medication to use. You will gain valuable insights into the latest developments in dermatology and the practical steps you can take to reduce the risk of antimicrobial resistance in your practice. Don’t miss this opportunity to learn from one of the leading experts in the field.

Presenters

Transcript:

Hello and welcome to this talk about otitis. We will also discuss how to use medicine better in the time of multi-drug resistance (MDR). We will focus on cytology.

Otitis is a topic close to my heart, as I’ve personally experienced its pain. Antibiotic stewardship is very important now because more bacteria are resistant, so we must use antibiotics carefully.

In this presentation, we’ll cover:

• A brief overview of ear anatomy and physiology.
• Normal ear microbiology and the significance of MDR.
• Symptoms and diagnosis of otitis using the PSPP system.
• What you see through an otoscope and worthwhile diagnostic procedures.
• Goals of therapy, MDR implications, and a summary.

Starting with dog ear anatomy, different breeds have varied ear shapes affecting airflow and temperature, impacting otitis risk. Springer Spaniels have floppy, hairy ears.

These ears allow less air to flow, which can lead to ear infections. German Shepherds have upright ears. Their ears get better airflow, which lowers the risk of infections.

Owners often can’t see the ear canal’s full depth, including the horizontal and vertical canals and the bulla. Explaining this anatomy to owners is crucial since they might assume the ear is clear when deeper issues persist.

It’s important to educate owners on ear care and cleaning before problems arise. Encourage regular ear checks at puppy parties and during general consultations.

Stress that ear manipulations by vets aren’t painful; the disease causes discomfort. Discuss whether plucking hairy ears is necessary, as it can provoke inflammation. Avoid damaging structures during ear cleaning, especially the tympanic membrane.

Regarding physiology, the ear canal contains sebaceous and ceruminous glands, producing lipids and cerumen to trap foreign bodies. Cerumen has antibacterial and anti-yeast properties. Keratinocytes migrate from the tympanic membrane outward, self-cleaning the ear.

Normal ear temperature is around 37.4°C, with 88.5% humidity and a pH of 6.1 to 6.2. Otitis increases temperature, humidity, and pH, with acute cases lowering pH and chronic cases making it alkaline.

The ear’s normal flora is primarily gram-positive bacteria, similar to skin flora. Common bacteria include coagulase-positive and negative staphylococci, Malassezia, micrococcus, and streptococcus. Otitis increases bacterial numbers, with shifts to gram-negative species like Pseudomonas in chronic cases. Studies show that diseased ears lose microbial diversity but gain microbial biomass, often with overgrowth of staphylococci or Malassezia.

High humidity and excessive wax favour microbial growth. Healthy ears can have some microbes.

However, patients with symptoms need treatment. They may use topical cleaners or disinfectants. In severe cases, they might need drops.

MDR is a global problem and a One Health issue. It is caused by the overuse of antibiotics in medicine, veterinary care, and farming.

Increased antibiotic use leads to more resistance. Some countries have strict legislation reducing MDR strains, while others with over-the-counter antibiotic access face rampant resistance. It’s vital for the veterinary profession to judiciously use antibiotics, opting for disinfectants and topical treatments over systemic antibiotics, especially for otitis.

Studies like those by Martins et al. reveal high MDR rates in otitis cases, with 50% of bacteria showing resistance. In contrast, Bouroulli et al. found slightly lower rates in France, with MDR in Proteus mirabilis and Staphylococci. Encouragingly, fluoroquinolone resistance has decreased for some bacteria since 2013. Continued vigilance and careful antibiotic use are essential.

Otitis is a common clinical presentation, often seen daily in practice. Recurrent cases frequently prompt owners to switch practices. Identifying and addressing underlying causes early is crucial to prevent recurrence and chronic changes.

Multiple antibiotic courses are common, but systemic antibiotics rarely achieve effective ear concentrations. Currently, no non-antibiotic drops are licensed in the UK; most are combinations of antibiotics, antifungals, and anti-inflammatories. Cleaners with disinfectants and antimicrobial peptides can be effective, but antibiotic-free options would be beneficial.

Common otitis symptoms include head shaking, odour, scratching, moisture or hot spots, head tilt, ear rubbing, and discharge. Otitis is often recurrent, requiring investigation of underlying causes rather than just symptomatic treatment. The PSPP system (Primary, Secondary, Predisposing, and Perpetuating factors) aids in diagnosing and managing these factors.

Primary factors include allergies (environmental and food hypersensitivity), ectoparasites (Otodectes, Demodex), endocrine diseases, keratinization disorders, foreign bodies, and immune-mediated diseases. Secondary factors involve bacterial (cocci, gram-negative rods) and yeast infections, with gram-negative bacteria requiring culture for resistance patterns.

Some factors can increase the risk of ear infections. These include droopy ears, narrow ear canals, and hairy ears. These conditions can raise the temperature and humidity in the ear. Perpetuating factors develop due to the disease, such as chronic inflammatory changes, gland hyperplasia, stenosis, middle ear disease, altered epithelial migration, and treatment effects.

A study by O’Neill et al. shows that certain dog breeds, like Basset Hounds and Golden Retrievers, are more likely to get ear infections. Conversely, Chihuahuas, Border Collies, Yorkshire Terriers, and Jack Russell Terriers show reduced odds. Certain ear types, like pendulous and V-shaped drop ears, are more predisposed.

Don’t just depend on drops; look into and fix all causes to stop chronic ear infections from happening. Each recurrence worsens the condition, leading to more severe and frequent episodes, often prompting practice changes by owners.

In managing otitis cases, I assess breed predisposition, take thorough histories, and gauge owner compliance and treatment tolerance. After a general and skin examination, I perform cytology on every otitis case, even in head-shy dogs. Treatment is based on clinical examination, discharge type, tympanic membrane visibility, and cytology. Follow-up is crucial to ensure treatment effectiveness and prevent resistance, avoiding leftover drops for future use.

During examinations, palpating the ear canal provides information on hardness, thickness, stenosis, and pain. Discharge type can guide cleaner choice, with watery cleaners for purulent discharge and cerumenolytic ones for waxy discharge.

Biofilm, a protective slime produced by bacteria and yeast, complicates treatment by shielding organisms from medication. Biofilm occurs with severe infections, often requiring deep ear flushing under anaesthesia. Tris-EDTA-based cleaners and acetylcysteine can dissolve biofilm.

Otoscopy gives important information. However, if the patient is in too much pain, using glucocorticoids first can help. This makes the patient more comfortable and allows for a better exam.

Be gentle when checking dogs with ear infections. Some dogs may have had painful experiences in the past. They might be scared of being touched.

Training dogs from a young age to tolerate ear handling can be beneficial, even if an otoscope isn’t used initially. However, otoscopy alone doesn’t provide a complete picture; cytology is a key component in understanding the condition of the ear.

Otoscopy involves using a cone to inspect the ear canal, and it’s important to warm the cone beforehand to minimize discomfort. Generally, one of my nurses will hold the dog’s nose while I gently stretch the pinna to open the ear canal. If the dog is particularly painful or head shy, sedation or general anaesthesia might be necessary to conduct a thorough examination. Even deep sedation might not prevent reactions in very painful cases, so general anaesthesia can sometimes be a better option.

With video otoscopy, various conditions can be observed. For example, a dark brown, waxy discharge typically indicates Malassezia otitis, while a purulent discharge might suggest a bacterial infection, such as a cockle infection.

Pseudomonas otitis presents with purulent discharge and potential ulceration. Over-cleaning by owners can also lead to problems, resulting in red, inflamed ear canals with persistent discharge.

A cerumenolith is a hard, waxy plug located in front of the eardrum, often requiring flushing for removal. A ruptured eardrum may be indicated by air bubbles and a visible tear in the membrane. In cats, polyps can cause infections and may need to be surgically removed.

For cytology, essential equipment includes a good quality microscope, stains like methylene blue, immersion oil, slides, cover slips, and cotton buds. Methylene blue is particularly useful for highlighting inflammatory cells, bacteria, and yeast.

It’s important to use a high-quality microscope with proper lighting and regular maintenance. To collect a sample, use a cotton bud to gently gather material from the ear canal, place it on a slide, and apply the stain. For very head-shy or aggressive dogs, a gloved finger can be used to collect a sample by gently inserting it into the ear canal.

When examining the cytology slide, look for specific indicators. Pseudomonas otitis shows characteristics such as nuclear streaming and bacteria, while Malassezia appears as pale or ghost cells. Identifying the types of bacteria and yeast is crucial for appropriate treatment. Cytology provides quick and cost-effective insights into the nature of the infection, though culture and sensitivity testing, while useful for identifying species and resistance patterns, can be delayed and may not always align directly with treatment outcomes.

Following cytology, create a problem list and consider differential diagnoses based on the patient’s age, symptoms, and history. For instance, allergies might be considered in a young dog with recurrent otitis, while hypothyroidism might be suspected in an older dog showing weight gain. This step helps in determining further testing or treatment options.

In terms of therapy, address the infection, remove discharge, provide analgesia, and manage chronic changes. Choose appropriate treatments, including cleaners, ear drops, steroids, and potentially systemic medications. Systemic antibiotics are rarely used as they might not effectively reach the ear canal, while steroids and cyclosporine can help with pain relief and treating underlying conditions.

Analgesia is crucial since severe otitis can be extremely painful. Gabapentin may be used off-label for pain management. It’s important to educate owners about long-term management strategies, such as regular ear cleaning, dietary changes, or immunotherapy if needed. For severe cases, general anaesthesia might be required for ear flushing, especially if there’s significant discharge or biofilm.

Client education and follow-up care are vital. Teach owners the correct way to clean their dog’s ears and set realistic expectations about managing the condition.

We cannot completely get rid of ear disease. Our goal is to improve the patient’s quality of life. We do this through good management and regular check-ups. Follow-up visits are determined by the severity of the condition and can range from weekly for severe cases to annually for ongoing management.