Ušesna obolenja malih živali - SZVMŽ · 2018. 1. 31. · Veterinarska dermatologija - Ušesna obolenja malih živali Drage kolegice, dragi kolegi Dobrodošli na letnem srečanju

Veterinarska dermatologija U š e s n a o b o l e n j a m a l i h ž i v a l i

Predavatelji:Prof. dr. Tina Kotnik, dr. vet. med.

Dr. Ursula K. Mayer, dr. vet. med., Dipl.ECVD, Cert.VDDr. Xenokratis Kostatos, dr. vet. med.

Predkongresni dan XXX. simpozija SZVMŽ o aktualnih boleznih malih živali, 30. marec 2017, Portorož, Slovenija

ZBORNIK REFERATOV

Univerza v LjubljaniVeterinarska fakulteta

ZBORNIK REFERATOV

Veterinarska dermatologija

Ušesna obolenja malih živali

Predkongresni dan XXX. simpozija SZVMŽ o aktualnih boleznih malih živali,

30. marec 2017, Portorož, Slovenija

http://www.zdruzenje-szvmz.si/

Predkongresni dan XXX. SIMPOZIJA SZVMŽ o aktualnih boleznih malih živali ZBORNIK REFERATOV

Portorož, 30. marec 2017

4

Vsebina

Mayer K. U. Therapy of otitis ........................................................................................................ 7

Kostatos X. Update on the treatment od demodectic, sarcoptic and otodectic mange

in companion animals ............................................................................................................... 13

Kotnik T. Pseudomonas aeruginosa ............................................................................................ 14

Veterinarska dermatologija - Ušesna obolenja malih živali

Drage kolegice, dragi kolegi

Dobrodošli na letnem srečanju dermatološke sekcije. Tema današnjega dneva so ušesna obolenja pri psih in mačkah. Dr. Mayer se bo po inicialnem pregledu osnov etiopatogeneze otitisa, osredotočila na terapijo, in sicer

medikamentozno in tudi video-otoskopično. Prof. Kotnik bo delila z nami svoje bogate izkušnje s področja infekcij z bakterijami Pseudomonas aeruginosa in predstavila zanimive primere. Dr. Kostatos pa bo še dodatno osvežil

program z novostmi s področja zdravljenja različnih vrst garij.

Kot vedno, bomo zelo veseli, če bodo predavanja interaktivna ker boste tudi sami vnesli čim več vprašanj in lastnih izkušenj. Tako upamo, da se bomo vsi veliko naučili. Veselimo se druženja z Vami.

S spoštovanjem,

Mihaela Bizjak, Ana Rostaher (v imenu SZVMŽ)

Ura Program Predavatelj

9:00 do 09:45 Otitis: etiopathogenesis and diagnostics Dr. Ursula Mayer

09:45 do 10:30 Otitis: therapy Dr. Ursula Mayer

10:30 do 11.00 Premor

11:00 do 11:45 Video-otoscopy and ear flushing Dr. Ursula Mayer

11:45 do 12.30 Update on the treatment od demodectic, sarcoptic and otodectic mange in companion animals Dr. X. Kostatos MSD AH

12:30 do 14:00 Kosilo (+ sestanek dermatološke sekcije ≈ 20 min)

14:00 do 14:45 Pseudomonas otitis Prof. Dr. Tina Kotnik

14:45 do 15:30 Otitis: Klinični primeri Prof. Dr. Tina Kotnik

Izdalo: Slovensko združenje veterinarjev za male živali

Oblikovanje:AKTA DESIGNwww.aktadesign.si

50 izvodov

ZBORNIK REFERATOV Predkongresni dan XXX. SIMPOZIJA SZVMŽ o aktualnih boleznih malih živali


5

ORGANIZACIJSKI IN UREDNIŠKI ODBOR SZVMŽ (UO SZVMŽ)

Prof. dr. Nataša Tozon, dr. vet. med. (predsednica)

Milan Matko, dr. vet. med. (podpredsednik - bodoči predsednik)

Doc. dr. Alenka Seliškar (podpredsednica – prejšnja predsednica)

Barbara Celinšek, dr. vet. med. (tajnik)

Tjaša Pukl, dr. vet. med. (blagajnik)

Doc. dr. Joško Račnik, dr. vet. med. (član)

Mag. Jure Pipp, dr. vet. med. (član)

ČASTNI ČLANI ZDRUŽENJA:

Prof. dr. Vjekoslav Simčič, dr. vet. med.

Prof. dr. Boyd R Jones, BVSc, FACVSc, DECVIM-Ca, MRCVS

Emil Mlinarič, dr. vet. med.

WORLD SMALL ANIMAL VETERINARY ASSOCIATION - WSAVA

OFFICERS

Dr. Walt Ingwersen, Executive Board Member, President

Prof. Colin Burrows, Executive Board Member, Past President

Dr. Shane Ryan, Executive Board Member, President Elect

Dr. Siraya Chunekamrai, Executive Board Member, Vice President

Dr. Ellen van Nierop, Executive Board Member, Honorary Treasurer

Dr. Nicola Neumann, Executive Board Member

Dr. Renée Chalmers Hoynck van Papendrecht, Executive Board Member, Honorary Secretary

FEDERATION OF EUROPEAN COMPANION ANIMAL VETERINARY ASSOCIATIONS - FECAVA

OFFICERS

Dr. Jerzy Gawor, President

Dr. Wolfgang Dohne, Vice President

Dr. Denis Novak, Treasurer

Dr. Ann Criel, Honorary Secretary

Dr. Monique Megens, Senior Vice-President

Prof. dr. Tina Kotnik, dr. vet. med.

[email protected]

Prof. Kotnik je zaključila študij veterine v Ljubljani, kjer je tudi nadaljevala in zaključila magistrski in doktorski študij na temo dermatologije (Mikrosporija). Ves čas od diplome (1991) je zaposlena na Kliniki za male živali VF v Ljubljani. S področja dermatologije se vsa leta dodatno izobražuje. Vidnejši so tečaji ESAVS Dermatology I, II in III ter večletno sodelovanje z diplomatom ECVD Nikšo Lemo iz Zagreba. Od leta 1993 vodi Dermatološko ambulanto KMŽ, ki obratuje trikrat tedensko. Opravlja tudi vodstveno funkcijo namestnice predstojnice klinike. Poleg operativnega dela s pacienti prof. Kotnikova opravlja tudi znanstveno raziskovalno in pedagoško delo. Do sedaj je objavila okrog 90 del in bila mentorica eni magistrantki, dvema doktorandoma in šestim študentom pri izdelavi Prešernove raziskovalne naloge, vse s področja dermatologije. Od leta 1996 je članica ESVD. Bila je ustanovna članica in prva predsednica Dermatološke sekcije SZVMŽ, ki je bila ustanovljena 29. marca 2008.

Dr. Ursula Mayer, dr. vet. med., Dipl. ECVD, Cert. VD, FTA Dermatologie Kleintiere

www.haut-tier-arzt.de

Dr. Mayer je zaključila študij veterine v Leipzig-u in na Dunaju, kjer je tudi opravila doktorsko dizertacijo iz področja veterinarske dermatologije. Medtem ko je delala v mali in veliki praksi, je še pridobila dermatološki specialistični naslov v Veliki Britaniji. Zatem je v Munchnu opravila 3-letni specilaistični program ter pridobila naziv »Diplomate of the European College of Veterinary Dermatology« ter specialistični nemški dermatološki specialistični naziv 2008 leta. Po nekajmesečnem delu kot docentka na univerzi v Pennsylvania, Philadelphia, se je ustalila na Bavarskem, kjer je delala v privatni praksi izključno kot dermatologinja in je od rojstva prvega sina dalje zaposlena v privatni referenčni veterinarski kliniki v Augsburgu. Od 2012 dalje opravlja tudi svetovalno delo za podjetje Idexx/Vet Med. Od 2010 do 2015 je bila tudi članica organizacijskega odbora ESVD (European Society of Veterinary Dermatology). Poleg kliničnega dela Dr. Mayer veliko predava in se še naprej udejstvuje na raziskovalnem področju.

Xenokratis Kostatos, dr. vet. med.

Technical & Marketing Manager Companion Animals, Greece, Cyprus, Bulgaria, Croatia, Slovenia

MSD Animal Health

Dr. Xenokratis Kostatos prihaja iz Grčije, kjer je tudi uspešno zaključil študij veterinarske medicine leta 1993. Od leta 1995 je zaposlen v veterinarski industriji, kot »Professional Affairs, Technical and Marketing Manager« (Hill’s Pet Nutrition, Bayer Animal Health in MSD Animal Health). V letu 2010 se je pridružil MSD Animal Health, kjer je njegova funkcija ti. » Technical & Marketing Manager« za male živali, za področje Grčije, Bolgarije, Hrvaške in Slovenije. Ima bogate izkušnje na področju razvoja veterinarksih izdelkov ter marketinga, sodeloval je velikokrat tudi na večjih internacionalnih projektih in uspešno obvlada krizni management. Dr. Kostatos je vabljen na številne seminarje in konference, kjer večinoma predava o prehrani, kontroli ekto- in endoparazitov, o infekcijah ter cepljenju predvsem pri psih in mačkah.

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7

THERAPY OF OTITIS

Ursula K. Mayer

I: Etiopathogenesis and diagnosis of Otitis

1.) Short anatomy important to diagnosis and ther-apy of otitis:

The ear is divided into three major portions: the exter-nal ear (pinna and external ear canal), the middle ear and the inner ear.

The external ears major function is the collection of sound waves and their transmission to the tympanic mem-brane. The external ear canal is lined by skin (including adnexa like glands and few hair follicles), in contrast to the middle ear, which is lined by a mucous membrane. As a normal self-cleaning mechanism of the ear the surface of the skin lining the ear canal is constantly moving outward, transporting desquamated epithelial cells, cerumen and microorganisms out of the ear. The length of the external ear canal varies (5-10cm in dogs; volume 0.5-2ml). The ex-ternal ear canal is divided into the vertical ear canal (pinna until medial bend) and horizontal ear canal (medial bend until tympanic membrane). At the medial bend there is a prominent dorsal skin fold. When performing otoscopy it is important to straighten out this fold by pulling the pinna dorsal and lateral to avoid touching it, which is very painful for most dogs with otitis.

The tympanic membrane is a specialized epithelial structure separating the external ear canal from the middle ear cavity. It consists of the pars tensa and the pars flac-cida. The normal pars tensa is translucent with striations. The manubrium of the malleus can be seen attached to the tympanum and has a C shaped appearance, with the open end of the C pointing cranially towards the nose. The pars flaccida lays dorsal, is vascular and in the dog can bulge out with increased middle ear pressure (air or fluid). The tympanic membrane is oriented in a 30-45 degree angle in the dog. This creates an angel, where accumulations of earwax as well as large primary hairs are often seen. These hairs may help localizing the tympanum in diseased ears.

The middle ear consists of the tympanic cavity, the au-ditory ossicles and the auditory tube, which opens into the nasal pharynx. The middle ear is divided into a dorsal, mid-dle and ventral part. The dorsal part (epitympanic recess) contains the auditory ossicles. The middle part (tympanic cavity proper) is adjacent to the tympanic membrane. Its

dorsal-medial surface is made up of the cochlear prom-ontory with the cochlear (round window – entrance to the inner ear), which should be avoided when perform-ing myringotomy and middle ear flushing. The ventral part (tympanic bulla) is egg-shaped and divided by a bony ridge (tympanic bulla ridge), which makes it very difficult to pass tubes for flushing into the ventral tympanic bulla. Struc-tures running close to or in channels along the middle ear include the facial nerve, vagus nerve, carotid and lingual arteries.

2.) Pathogenesis and classification of otitisFor successful therapy of otitis it is very important to

address all causes (primary and secondary) as well as fac-tors (predisposing, perpetuating) involved. Many combina-tions of causes and factors may be seen. By combining predisposing factors and secondary causes otitis may result even without a primary cause. On the other hand prima-ry causes (e.g. atopy) may not result in apparent clinical symptoms until aggravated by secondary causes, predis-posing or perpetuating factors. These combinations also explain why dogs with a bilateral symmetric primary cause (allergy) may show recurrent unilateral otitis with second-ary infections. (See Table 1: causes and factors of otitis)

3.) Ear cytologyEar cytology is very useful in determining what infec-

tious agent is present and initial medical therapy can be based on it. Since gram positive cocci and yeast are found in most normal ears, it is a better diagnostic measure than culture in these cases. This is because it is able to assess relative numbers as well as inflammatory cells. Further cy-tology is a fast and cheap diagnostic method and should be used routinely in all cases of otitis. A clean cotton swab is passed down the vertical ear canal were it bends medi-ally to obtain a sample of discharge representative for the deeper levels of the canal. The swab is then rolled onto a glass slide, which should be heat fixed and stained with Diff Quick® (Modified Wrights stain). With this stain all bacteria stain blue, therefore differentiation of gram posi-tive and gram negative is not possible. If cocci are found there is a > 90% chance that it is Staphylococcus pseud-intermedius. If rods are found the most common bacteria are Pseudomonas aeruginosa, E. coli, Klebsiella and, Pro-teus. A bacterial culture and sensitivity should be mainly performed if otitis media is suspected and/or systemic therapy indicated. Malassezia and inflammatory cells can also easily be evaluated with this method.

Dr. vet. med. Ursula K. Mayer, DipECVD, CertVD, FTA Dermatologie Kleintiere, Tierdermatologie Mayer, Anicura Kleintierspezialisten Augsburg, Germany



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4.) Otoscopy and ear flushingOtoscopes must have a strong light and power source

combined with at least a 10x magnification lens. Surgi-cal otoscopes have the advantage that instruments can be passed into the ear canal while observing. Various sizes of otoscope cones are needed for cats and the different dog breeds. A clean otoscope cone should be used in each ear. In a in vitro study (Newton et al. 2006) evaluating the efficacy of otoscope cone cleaning after inoculation with Pseudomonas soaking for 20 min in Cetylcide II and chlo-rhexidine gluconate 2% solutions were most effective. Improved visualization is possible with Fiber optic Video Enhanced Otoscopy (FOVOE). This also allows recording if connected to a digital recorder/printer. Other useful instru-ments are bulb syringes, feeding or urinary catheters for flushing, long needles and ear curettes or loops.

Diagnosis of otitis media is not as easily determined as with otitis externa. Nerve damage and mandibular disease are indicative of otitis media, but many dogs with otitis media show the same clinical signs as with otitis externa. Imaging can be diagnostic, if middle ear pathology can be demonstrated. Herein CT (computer tomography) and MRI (magnetic resonance imaging) are more sensitive than radiographs. But normal imaging does not rule out otitis media. Otitis media can only be ruled out when a normal appearing tympanic membrane is present.

II. Medical therapy of otitis

Otitis externa is best treated topically (except when extensive ulceration is present), since it is very difficult to achieve desired tissue levels on the skin surface and in the fluid of the lumen of the ear canal with systemic therapeu-tics. Cultures of the exudate from the external ear canal are rarely needed, since information from sensitivity test-ing reflects the serum level of a drug required to kill the organism cultured. It is usually expressed in MIC (minimal inhibitory concentration) or reported susceptible, interme-diate or resistant based on the Kirby-Bauer disk diffusion method. This may not be relevant in choosing topical an-timicrobial preparations, since topical formulations usually contain drug concentrations that greatly exceed those that could be safely achieved in the systemic circulation. There-fore veterinarian should be comfortable with basing an empirical choice of topical antimicrobial on the cytologi-cal identification of class of organism and otoscopic evalu-ation of the extent of ear canal inflammation, nature of exudate and chronic changes(see tables 2-4).

If otitis media is present additional systemic therapy is indicated because antibiotics are delivered very well to the highly vascular mucous membrane lining the middle ear. Also it is more difficult to reach the middle ear cavity with topically applied medications.

Ear cleaning is critical in management of otitis externa. Many ear cleaners do also alter the ph and have mild anti-microbial activity. For example acidifying ear cleaners have efficacy against Malassezia. The new formulation of Epi-otic® contains sugars that decrease bacterial adherence to corneocytes. Most commercial ear medications contain an antibacterial, an antifungal and an anti-inflammatory

agent as well as vehicles, stabilizers, solubilizers and sur-factants. Many vehicles are also potentially ototoxic or can elicit contact dermatitis. Glucocorticoids have many ben-eficial effects in otitis externa. They are antiinflammatory, antiproliferative, antipruritic, decrease gland secretions and pain. Drug potency depends on the glucocorticoid, its concentration and vehicle base.

Therapy of typical cases:

Therapy of acute otitis externa: in general for a first time case a fist-line antimicrobial,

based on cytology should be used twice daily for 7 to 14 days. The volume applied to the ear should be adjusted to the animal’s size. Large breed dogs (eg. Labrador, German Shepherd dog) should receive a minimum of 1ml (10-12 drops) per ear. This should be preceded by one to twice daily ear cleaning (about 15-30 minutes prior). It is essen-tial that after this time the animal is reevaluated and cytol-ogy and otoscopic examination repeated, to prove that the otitis was fully cleared. Fortyeight hours before reevalu-ation nothing should be administered into the ear canal by the owner to avoid false cytological results because of remaining medication in the ear canal.

Therapy of parasitic otitis: Since these are often secondarily infected with bacteria

or yeast cytology should always be performed. If infection is present above regimen should be applied. All mites, except for Demodex spp. can be treated with selamectin (Strong-hold®) or moxidectin (Advocate®) three treatments two weeks apart as a spot on between the shoulder blades (Caution: every two weeks is off label in most countries). In contact animals should be treated too, since clinically normal carriers are reported. Some topical ear medications do also contain miticidal substances like Lindan in Orisel® or Ivermectin in Otimectin®. In my experience they work in many animals, but I see more recurrences than with Stronghold®. Otic demodicosis is mostly associated with generalized demodicosis. For therapy I recommend the practice guidelines on treatment of demodicosis by Muel-ler, R et al. (2011) available as free publication via Pubmed (https://www.ncbi.nlm.nih.gov/pubmed/22329600).

Therapy of chronic recurrent otitis externa: Here search for predisposing, primary, secondary and

perpetuating factors is mandatory. These need to be iden-tified and addressed for successful therapy. The status of the tympanic membrane should be confirmed. Often topical and/or systemic glucocorticoids (e.g. prednisolone 0.5mg/kg twice daily, tapered weekly to every 24 and then every 48 hours) for 1-2(4) weeks are needed to reverse the edema and chronic changes of the ear canal and to be able to open up the ear canal far enough so visualization of the tympanum is possible. Second or third-line antimicrobials may need to be used topically, depending on cytology and previous drug history. The owners should be prepared for intensive diagnostic work up and prolonged topical thera-py (sometimes months), depending on chronicity. Systemic antibiotics may be indicated in some cases if there is deep infection of the skin in the ear canal or extensive ulcera-tion. Rechecks should be scheduled every 2 to 4 weeks for



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cytological and otoscopic evaluation until complete reso-lution is achieved. Often an ear flush under anesthesia is necessary 2-6 weeks into treatment to assess the ear drum and help heal the otitis.

Therapy of otitis media: Since otitis media is commonly the result of a ruptured

tympanic membrane and extension of chronic otitis ex-terna, all principles explained above are also mandatory here. Additionally an ear flush under anesthesia to perform middle ear probes for culture and sensitivity, as well as cleaning out infective and inflammatory exudates is most times needed and speeds up resolution. Systemic antibiot-ics should be administered based on culture and sensitivity.

6.) SurgeryIf calcification of the ear canal or osteomyelitis are pre-

sent a total ear canal ablation (TECA) and bullaosteotomy is recommended. With the exception of tumor or polyp re-moval, surgery rarely eliminates all the causes of a chronic otitis. Lateral ear canal ablation and vertical ear canal ab-lation are only indicative if anatomical abnormalities are present only in these parts of the ear canal with no other primary causes of otitis. This is not the case in most chronic otitis patients.

III. Videootoscopy and earflushing

Video otoscopy and ear flushing under anesthesia can not only be used as a diagnostic tool and to obtain probes for culture and sensitivity testing from the middle ear. It is also an important component of the therapy in severe and chronic cases otitis externa and media. Lens fogging and dirtying the lens with debris can be a major cause of frustration. Simultaneously flushing the canal with warm (body temperature) saline minimizes this complication. This also increases magnification and gently cleanses the ear canal. Assessing the tympanic membrane is not always easy in diseased ears, since it is no longer translucent and can be confused with impacted keratinous and inflamma-tory debris. Assessment of the depth of the canal (prac-tice in normal dogs will help to develop a feel for normal length of the ear canal) and location of the tip of a feeding tube can help. An intact tympanum will also move from the pressure of the tube or water being infused and then retracted back. The observation of fluid coming out of the nares or failure to retrieve all fluid infused, along with swallowing in an awake dog are indicative of a ruptured tympanic membrane. Therefore ear flushing in anesthesia always requires intubation to prevent aspiration pneumo-nia.

If there is suspicion of otitis media with an intact tym-panum myringotomy is generally performed. In most of these cases the tympanum had been perforated, but has been re-healed. Retrograde infections moving up the Eu-stachian tube or hematogenous spread are also possible explanations, although much rarer. Prior to myringotomy the external ear canal should be thoroughly cleaned to avoid spreading infectious agents into the middle ear. The site for performing myringotomy is at 6 to 7 o clock, over the ventral caudal part of the pars tensa of the tympanic

membrane. A stiff urinary catheter (tip cut off) or long nee-dle attached to a syringe can be used. Before flushing the middle ear some fluid should be obtained under preferably sterile criteria for culture and sensitivity testing, by apply-ing negative pressure via the attached syringe.

References:

Griffin CE (2006), Otitis techniques to improve practice. Clin Tech Small Anim Pract. 21(3):96-105.

Gortel K (2004), Otic flushing. Vet Clin North Am Small Anim Pract. 34(2):557-65.

Gotthelf LN (2005), Small Animal Ear Diseases: An Illustrated Guide. Elsevier, Philadelphia, USA.

Harvey RG, Harari J, Delauche AJ (2001), Ear diseases of the dog and cat. Iowa State University Press, Iowa, USA.

Lanz OI, Wood BC (2004), Surgery of the ear and pinna. Vet Clin North Am Small Anim Pract. 34(2):567-99

Mansfield PD et al. (1997), The effects of four, commercial ceruminolytic agents on the middle ear. J Am Anim Hosp Assoc. 33(6):479-86

Morris DO (2004), Medical therapy of otitis externa and otitis media. Vet Clin North Am Small Anim Pract. 34(2):541-55

Mueller RS et al. (2012), Treatment of Demodicosis in dogs: 2011 clinical practice guidelines . Vet Dermatol. 23(2):86-96.

Nardoni S et al. (2008), Diagnostic and clinical features of animal malasseziosis. Parassitologia. 50(1-2):81-3

Newton HM et al. (2006), Evaluation of otoscope cone cleaning and disinfection procedures commonly used in veterinary medical practices: a pilot study. Vet Dermatol. 17(2):147-50.

Nuttall T, Cole LK (2007), Evidence-based veterinary dermatology: a systematic review of interventions for treatment of Pseudomonas otitis in dogs. Vet Dermatol. 18(2):69-77.

Swinney A et al. (2008), Comparative in vitro antimicrobial efficacy of commercial ear cleaners. Vet Dermatol. 19(6):373-9.



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Tables:Table 1: causes and factors involved in otitis

Table 2: classification of ear cleaners

Predisposing factors

Conformation (Pendulous pinna, stenotic canal, excessive hair + glands)

Environment (humidity, heat)

Obstructive disease (polyp, cystadenomatosis)

Immunosuppression

Aggressive cleaning, hair plucking

Class

Acidifying

Alkalizing

Ph neutral

Example

Acetic acid (e.g. Malacetic)

Epiotic (old formulation)

TrisEDTA (tromethamine-ethylenediamine-tetraacetate)

Epiotic (new formulation)

Comment

Dont use with aminoglycosides

Increases permeability of bacterial cell wall – antibiotic can enter (esp. flouroquinolones, aminoglycosides in gram negatives)

Primary causes

Allergic disease

(atopic dermatitis, adverse food reaction, contact allergy)

Parasites (Otodectes, Demodex, ticks)

Endocrine disease (hypothyroidism, hyperadrenocorticism)

Autoimmune (pemphigus foliaceous, erythema multiforme)

Epithelialization disorders (primary seborrhea, sebaceous adenitis)

Foreign bodies

Miscellaneous (juvenile cellulitis, idiopathic facial dermatitis of Persian cats, perforating necrotizing otitis of kittens)

Neoplasia

Occasionally gram negative rod bacteria

Secondary causes

Bacteria

Staph. pseudintermedius

P. aeruginosa

Yeast

Malassezia pachydermatis

Contact irritant reaction to topicals

Perpetuating factors

Proliferative changes of the skin and glands - stenosis, folds

Hyperkeratosis + hypersecretion – increased cerumen

Abnormal cleaning mechanism

Changes of the tympanic membran

Otitis media,

Calcification

Osteomyelitis



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Table 3: other ingredients commonly contained in topicals for the ear

Table 4: examples of ear cleaners

Class

Drying agents

Cerumenolytics

Antibacterial

Antifungal

Skin barrier

Vehicles

Disinfectants

Detergents

Product

Epiotic®, Virbac (new)

Malacetic®, Albrecht

TrizEDTA®, Albrecht

Douxo®, Solgeval

Main ingredients

Salicylic acid 0.2%, PCMX, Sodium Dokusat, EDTA, monosaccharid complex

2% boric acid, 2% acetic acid, surfactant, water

553mg TrizEDTA

Phytosphingosine, nonionic surfactant, polysaccharide complex, poliphenol, fragrance

Example

Burrow’s solution (Aluminium acetate)

Alcohol

Acetic acid, boric acid, salicylic acid

Squalene (Episqalan®)

Propylene glycol

Dioctyl Sodium Sulfosuccinate

Acetic acid, boric acid, salicylic acid

Chlorhexidine

PCMX (Parachloromethylxylenol)

Some polysaccharids (new Epiotic®)

TrisEDTA

Acetic acid above 2%

Chlorhexidine above 2%

Phytosphingosine (Douxo®)

Water

Demulcents (for emulsions or suspensions with water insoluble drugs)

Emollients (occlusive, carry water insoluble drugs)

Chlorhexidine, alcohols

Sodium lauryl sulfate

Comment

Irritates eroded or ulcerated ear canals

Only non-ototoxic

Poss. ototoxic if > 0.2%

Also antimicrobial activity

Polyethylene glycol, Propylene glycol, glycerine

Hydrocarbons, animal fat, vegetable oils

Ototoxic

Ototoxic



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Table 5: topical antimicrobial therapy

Organism on cytology

Cocci

Rods

MRSP (methicillin resistant Staph. pseudointermedius)

Yeast

Active ingredient

Neomycin

Gentamicin

Polymyxin B + Miconazole

Silversulfadiazine

Gentamicin

Flouroquinolones(Enrofloxacin, Marbofloxacin)

Polymyxin B

Silver sulfadiazine (SSD)

Amikacin

Ticacillin

Based on culture and sensitivity

Nystatin

Thiabendazole

Clotrimazole

Miconazole

Comment

First-line antibacterial, good for gram positive cocci, but most P.aeruginosa resistant, ototoxic potential

Second-line antibacterial, ototoxic potential especially in cats

Second-line antibacterial, Polymyxin B poss. ototoxic

Third-line antibacterial, not commercially available as ear preparation for animal.

Resistant strains of E.coli and P.aeruginosa not uncommon

Flourequinolones bacterial resistance occurs by rapid mutation especially in sub therapeutic concentrations. Good efficacy for gram pos cocci and gram negative rods (but increasing resistance esp. with Enrofloxacine)

Neutralized endotoxins of gram negative bacteria, inactivated by pus, ototoxic potential

Third line: Gram pos cocci and P.aeruginosa. Resistance is very rare. Positive effects on wound healing. Ototoxic potential unknown. 1% creme (human medicine) or 1% solution out of micronized powder

Third-line (reserve antibiotic) for gentamycin resistant gram negative bacilli (Pseudomonas ae.), injectable diluted to concentration of 30-50mg/ml in sterile saline or TrisEDTA

Third-line (reserve antibiotic) for resistant P.aeruginosa. Dilute 6g injectable with 12ml of sterile water. Add 2ml of that solution to 40ml of acidifying ear cleanser (only stable for 3-7 days). Freeze.

Polymyxin B, SSD, Chloramphenicol more often sensitive

First-line antimalassezia

First-line antimalassezia

Second-line antimalassezia

Third-line antimalassezia, resistance very rare



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UPDATE ON THE TREATMENT OF DEMODECTIC, SARCOPTIC & OTODECTIC MANGE IN COMPANION ANIMALS

Xenokratis Kostatos

Abstract

Generalised demodicosis has been a frustrating and challenging disease to treat. Currently available treat-ments include weekly amitraz rinses and daily oral macro-cyclic lactones such as milbemycin oxime, ivermectin and moxidectin. Weekly application of topical moxidectin can be useful in dogs with milder forms of the disease. Also, there is some evidence for the efficacy of weekly or twice weekly subcutaneous or oral doramectin. To be effective, these treatment regimens require high owner compliance over an extended period of time (usually three months or more).

One of the most common reasons for treatment fail-ure is ending therapy too soon, i.e., after clinical resolution but before parasitic cure is achieved, alongside with poor owner compliance (as conventional treatments are difficult or tedious to administer). Relapses, occurring within a few months from treatment discontinuation, are reported in 10-45% of patients. Moreover, adverse reactions, espe-cially neurological signs, are not uncommon when macro-cyclic lactones are used for longer term or in MDR-1 gene deficient dog breeds, such as Collies, further undermining compliance and treatment outcome. Hence, practitioners should:

• Perform recheck visits and skin scraping tests every 4 weeks to monitor response; it is recommended to scrape repeatedly the 3-5 most severely affected ar-eas and any new lesions monthly, until 2 consecutive negative skin scraping tests, at least 4 weeks apart, are obtained. The presence of any live, dead and/or fragments of Demodex mites should be considered positive.

• Continue treatment for 1 month after the second neg-ative monthly set of skin scrapings or even further in dogs that responded very slowly to therapy.

• Monitor patients for 12 months after treatment is dis-continued, with rechecks and skin scrapings every 3-4 months to monitor for relapses.

Also, effective long-term treatment should include:

• Topical and/or systemic antimicrobial therapy

• Good control of endoparasites

• Feeding a balanced, high-quality diet

• Diagnosis and treatment of underlying systemic dis-eases (e.g., hyperadrenocorticism, hypothyroidism).

• Avoiding the use of immunosuppressive drugs and conditions

• Client education about the length, complexity and cost of the treatment as well as the possibility of ad-verse reactions and recurrence

Recently, systemic isoxazoline parasiticides, such as flu-ralaner, afoxolaner and sarolaner have emerged as new off-label treatment options for canine generalized demodi-cosis. In one study, oral afoxolaner (administered 4 times on days 0, 14, 28 and 56) achieved 100% mite reduction. In another study, 3 monthly treatments of oral sarolaner also resulted in 100% mite reduction.

In three different studies, a single oral administration of fluralaner was proven effective in eliminating Demodex mites (100% efficacy) and significantly reducing the skin lesions. Fluralaner is safe to use in MDR-1 gene deficient Collies and may be considered as an alternative to macro-cyclic lactones. Also, it is safe in breeding, pregnant and lactating dogs; thus, it might prove an effective prophy-lactic intervention against the transmission of Demodex mites from a lactating bitch to her new-born pups.

Similarly, in one study the efficacy of fluralaner (single oral or topical administration) has been evaluated against naturally acquired Sarcoptes scabiei var. canis infestation in dogs, resulting in 100% reduction in mite counts and improvement of clinical signs. Finally, one single treatment with fluralaner (either orally in dogs or topically in dogs and cats) resulted in 99,8% reduction in Otodectes cyno-tis mite counts in dogs and 100% reduction in cats and significant improvement in the amount of cerumen exuda-tion; no mites were visible during otoscopic examination in dogs (Day 28) and cats (Days 14 and 28).

The long, 12-week systemic efficacy of a single treat-ment with fluralaner may help overcome poor owner com-pliance and thus reduce the risk of treatment failure.

Xenokratis Kostatos, dr. vet. med. Technical & Marketing Manager Companion Animals, Greece, Cyprus, Bulgaria, Croatia, Slovenia MSD Animal Health



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PSEUDOMONAS AERUGINOSA

Tina Kotnik

Pseudomonas aeruginosa (PA) je pogojno patogena, fakultativno anaerobna, G-negativna bakterija, ki se nahaja v vodi, zemlji in rastlinah. Okužbe lahko povzroča pri živalih in ljudeh, izpostavljeni pa so imunsko kompromitirani os-ebki. Pogosto povzroča kronična vnetja zunanjih sluho-vodov pri psih. Zaradi slabo prepustne celične ovojnice je naravno odporna proti aminoglikozidom, fluorokinolonom in beta-laktamskim antibiotikom. Poleg tega z mutacijo ali pridobivanjem genov, ki kodirajo rezistenco na antibiotike (na primer s pomočjo plazmidov), hitro postane odporna proti večini antibiotikov. Na splošno lahko t.i. intrinzično rezistenco bakterij razložimo z dejstvom, da so določene elemente odpornosti našli že pri bakterijah, starih 30 000 let, izoliranih iz večnega ledu. To nakazuje, da so se nara-vni antibiotiki razvili že dolgo nazaj. Evolucija odpornosti bakterij na antibiotike je torej naravni proces, ki je potekal že dolgo pred človekovim odkritjem antibiotikov. Vendarle pa je neracionalna raba antibiotikov - vse od njihovega od-kritja v 20 stoletju - zelo pospešila pojav rezistence bakterij (Fair in Tor, 2014).

Pseudomonas aeruginosa je bakterija, ki proizvaja mnoge faktorje virulence. Ti so proteaze, elastaze, piocia-nin, eksotoksin A, fosfolipaza C in eksoencim S. Pomaga si tudi z lipopolisaharidi, migetalkami in pili. S posebnim sistemom sekrecije izloča citokine neposredno v celice gos-titelja. Je zelo odporna na vplive okolja in potrebuje malo prehranskih snovi za preživetje. Preživi lahko celo v gorivu reaktivnih letal in v razkužilih. S številnimi nosilci železovih ionov in pigmenti je invazivna za celice takojšnjega imun-skega sistema (Fair in Tor, 2014). Bakterija ima sposobnost pripenjanja (adherence) na razne površine - na primer pulte v proizvodnji živil, medicinske inštrumente, tkivne vs-adke in epitelne celice in-vivo. Na njih tvori biofilm. Biofilm sestoji iz bakterijskih kolonij, vpetih v matriks, ki je sestav-ljen iz ekstracelularnih polimerov. Biofilm kolonijo ščiti pred delovanjem imunskih celic in omogoča komunikacijo med bakterijami s pomočjo sporočilnih molekul, kar imenujemo Quorum sensing (QS) (Abdullahi s sod., 2016; Pires s sod., 2015). Poleg tega biofilm bakterije mehansko ščiti pred antibiotiki, na katere bi bile sicer občutljive. Po nekater-ih podatkih so za uničenje bakterijskih kolonij v biofilmu potrebne do 1000 x večje koncentracije antibiotika, kot bi ga potrebovali za uničenje planktonične oblike bakterij (Abdullahi s sod., 2016).

DIAGNOSTIKA OKUŽB Z MIKROORGANIZMI, KI PROIZVAJAJO BIOFILM

Bakterije v biofilmu so na okuženo tkivo tako trdno pripete, da je rezultat gojiščne preiskave velikokrat neg-ativen, ali pa dobimo lažno pozitiven rezultat prosto gi-bljivih kontaminantov, ki so se znašli v bližini. Ustrezne diagnostične tehnike so zato serološka diagnostika, fluo-rescentna in- situ hibridizacija, CT, MR, PCR in druge molekularne tehnike. V diagnostiki vnetij srednjega ušesa v humani medicini se je kot zelo uporabna izkazala nein-vazivna mikroskopska tehnika, znana kot »laserska pregle-dovalna konfokalna mikroendoskopija«. Tehnika omogoča opazovanje biofilma na sluznicah votlih organov kot je GI trakt, urinarni trakt ali votlina srednjega ušesa (Abdullahi s sod., 2016).

PSEUDOMONASNI OTITIS

Pseudomonasni otitis je gnojno vnetje sluhovodov, ki se klinično kaže z ulceracijami kože sluhovoda ter močno bolečino, ki zahteva takojšnje zdravljenje. Pseudomonas aeruginosa je poleg Staphylococcus pseudintermedius najpogostejši povzročitelj kroničnega vnetja ušes pri psih (Cole s sod., 1998). Kronično vnetje je tisto, ki se ne odzi-va na medikamentozno zdravljenje, traja neprekinjeno več kot dva meseca ali se pogosto ponavlja (Doyle s sod., 2004). Pogost spremljevalec kroničnega vnetja zunanjih sluhovodov (v 50% - 80% primerov) je vnetje srednjega ušesa (Otitis media). Bakterije pri psih v srednje uho vdrejo skozi predrt bobnič, ki pri okužbah s PA nastane spontano. Zaradi razjed sluhovoda, ki spremljajo pseudomonasni oti-tis, se izloča velika količina seruma, ki privede do maceraci-je epitelija bobniča. Do maceracije privede tudi povečana količina vnetnega eksudata. Ker ima zunanji sluhovod ob-liko črke L se vnetni eksudat nabira ob bobniču. Vnetni eksudat vsebuje proteolitične encime, ki jih PA izloča v okolico, vnetne celice pa izločajo lizocime. Proteolitični en-cimi in lizocimi delujejo na maceriran epitel bobniča, kar privede do nekroze epitelija in kolagenih vlaken, bobnič se stanjša in oslabi ter v končni fazi pride do spontanega predrtja (Gotthelf, 2004). Bobnič ima sicer dobro sposob-nost celjenja in se po predrtju zaceli v 21 -35 dneh (Steiss s sod., 1992), zato nepoškodovan bobnič v času pregleda še ne zagotavlja, da do vdora infekta v srednje uho ni prišlo (Miller s sod., 2013). Intakten bobnič je lahko prisoten v času našega pregleda v kar 71% primerov vnetja srednjega ušesa pri psih (Cole s sod., 1998).

Prof. dr. Tina Kotnik, dr. vet. med. Klinika za male živali Veterinarska fakulteta Univerze v Ljubljani



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Klinično je vnetje srednjega ušesa velikokrat težko ugo-toviti, saj večina pacientov kaže le simptome vnetja zunan-jega sluhovoda. Pri kroničnem vnetju se epitel sluznice, ki ga imenujemo mukoperiost, značilno spremeni iz kuboidnega v stolpičastega, kar privede do povečanega števila celic in žlez, ki izločajo eksudat. Na sluznici nastanejo razjede, lam-ina propria zadebeli in ožiljenost se poveča. Nastane edem in razrašča granulacijsko tkivo. Nastane lahko septični ar-tritis slušnih koščic z začasno izgubo sluha ali osteomielitis s trajno izgubo sluha. Obilen vnetni eksudat drenira skozi predrt bobnič v horizontalni del sluhovoda ter preprečuje njegovo celjenje. Ko z ustreznimi zdravili ustavimo vnetje, se zmanjša tudi proizvodnja in pritisk vnetnega eksu-data, bobnič se lahko zaceli in vnetje srednjega ušesa je pozdravljeno (Gotthelf, 2004). Vendar klinična ozdravitev ne pomeni vedno tudi mikrobiološke ozdravitve (podatki o klinični in mikrobiološki ozdravitvi se namreč lahko ra-zlikujejo kar v tretjini primerov), zato bi morali uspešnost zdravljenja vedno ocenjevati tudi na podlagi mikrobiološke preiskave po zdravljenju (Nuttal s sod., 2007).

ZDRAVLJENJE PSEUDOMONASNEGA VNETJA

Pomemben del uspešnega zdravljenja vnetja sluhovo-dov je temeljito čiščenje. Izpiranje s pomočjo katetra je edino učinkovito in ustrezno pri zdravljenju vnetja sredn-jega ušesa. Globoko izpiranje vedno opravimo v anesteziji z intubacijo živali, sicer pri poškodovanem bobniču lahko pride do aspiracije tekočine, ki med izpiranjem priteče sko-zi evstahijevo tubo v žrelo. Veterinar bi pri tem postopku moral nositi rokavice, obrazno masko in zaščito za oči v izogib okužbi s kontaminiranim aerosolom. Pred izpiranjem odvzamemo brise zunanjega in v primeru predrtja bobniča tudi izpirke srednjega ušesa. Kadar uvajamo kateter v sred-nje uho je pomembno, da konico usmerimo ventralno in se tako izognemo občutljivim strukturam v dorzalnem delu. Dokler se ne prepričamo, da je bobnič nepoškodovan, za izpiranje uporabimo toplo fiziološko raztopino. Uporaba večine ceruminolitikov, detergentov in dezinficiensov je namreč pri predrtem bobniču kontraindicirana, saj delujejo ototoksično. Izmenično izpiramo in izsesavamo tekočino, dokler ne dobimo čistega izpirka. Na koncu uporabimo ad-stringent (na primer 3% ocetna kislina), s katerim osušimo sluhovod (Nuttal in Cole, 2004). Tekočina, ki zaostane v buli timpani po spiranju, se običajno resorbira v 7-10 dneh (Gotthelf, 2004). V večini kroničnih primerov z enkrat-nim izpiranjem sluhovodov ne moremo zadovoljivo rešiti problema vnetja. Alternativna rešitev je, da lastnik živali nadaljuje z izpiranjem doma. Najučinkovitejša frekvenca izpiranja doma je vsakih 48 ur, da se uho med posamezni-mi izpiranji tudi zadosti posuši (Miller s sod., 2013). Včasih je sluhovod tako ulceriran, otekel in boleč, da ga ne more-mo dovolj dobro pregledati niti v splošni anesteziji. Take primere je nujno najprej zdraviti, svetuje se 2-3 tedenska terapija s topikalnimi ali sistemskimi glukokortikoidi. Upo-rabimo prednizolon 1 - 2 mg/kg/24 ur p/o, nato odmerek zmanjšujemo (Nuttal in Cole, 2004).

Novejša doktrina zdravljenja vnetja srednjega ušesa priporoča aplikacijo topikalnih zdravil v bulo timpani. Z vnosom zdravil neposredno v bulo timpani dosežemo vi-soko koncentracijo zdravila na mestu vnetja, ki bi jo zaradi oslabljene oskrbe s krvjo težko dosegli po hematogeni poti.

Prenizka koncentracija antimikrobnega zdravila na mestu vnetja je običajno glavni razlog za neuspešnost zdravljenja. Topikalno vneseno zdravilo ostane v buli timpani v viso-ki koncentraciji, saj zaradi položaja bule timpani le malo vnesenega zdravila izteka v zunanji sluhovod. Aplikacijo topikalnega zdravila ponavljamo vsak teden. Uporabimo topikalna zdravila, ki niso ototoksična. Varni antibiotiki, ki jih lahko apliciramo v bulo timpani, so fluorokinoloni (ciprofloksacin, enrofloxacin, ofloxacin, marbofloxacin), vodotopni penicilin G, nekateri polsintetični penicilini (kar-benicilin, tikarcilin) in cefalosporini (ceftazidim, cefmenok-sin) (Ghubash s sod., 2004). Kadar imamo opravka z zelo rezistentnimi sevi PA, včasih tvegamo ototoksičnost z ap-likacijo sicer učinkovitega zdravila v bulo timpani. Tak je na primer tobramicin, na katerega rezistenca PA še ni pogos-ta. Tris-EDTA je varno čistilo za spiranje srednjega ušesa. Tudi vodne oblike protivnetnih zdravil (dexametazon, fluo-cinolon) so varne za topikalno uporabo v srednjem ušesu.

Topikalno zdravljenje kombiniramo s sistemskimi zdravili, izbranimi na podlagi antibiograma. Uporabimo sistemska zdravila, ki penetrirajo kostno tkivo in sicer v najvišjih priporočenih odmerkih. Običajno izbiramo med naslednjimi antibiotiki: Trimetoprim-sulfadiazin (Primo-trenR, Lek) 25 mg/kg/12 ur, ormetoprim-sulfadimethoxin (PrimorR, Pfizer) 55 mg/kg prvi dan, nato 25 mg/kg/24 ur; klindamicin (AntirobeR, Upjohn) 7-10 mgIkg/12 ur, cefalex-in (OracefR, Lek) 22 mg/kg/12 ur, enrofloksacin (EnroxilR, Krka) 5-20 mg/kg/24 ur; orbifloksacin (OrbaxR, Schering-Plough) 2,5-12,5 mg/kg/24 ur; ciprofloxacin (CiprobayR, Bayer) 20 mg/kg/24 ur.; marbofloxacin 5 mg/kg/24 ur.

Kronično vnetje sluhovodov, ki preide v končni stadij bolezni, je rešljivo samo s kirurškim zdravljenjem. Končni stadij bolezni nastopi takrat, ko pride do ireverzibilne ste-noze horizontalnega dela sluhovoda s kalcifikacijo hrustan-ca (Doyle s sod., 2004). Edina uspešna kirurška metoda zdravljenja kroničnega otitisa je TECA/LBO (Totalna ab-lacija sluhovoda z lateralno osteotomijo bule). Vendarle pa odličnih rezultatov ne moremo pričakovati, če je pri-marni vzrok vnetja alergijska bolezen in te ustrezno ne zdravimo. Poleg tega so tudi pri tej metodi v tretjini prim-erov možni postoperativni zapleti v obliki dehiscence ran, deficitov obraznega živca, vestibularnega sindroma, par-aaurikularnih abscesov s fistuliranjem in izgubo ušesnega hrustanca. Polovica nevroloških znakov je lahko ireverzi-bilnih (Doyle s sod., 2004).

ALTERNATIVNI NAČINI ZDRAVLJENJA

Novejša literatura priporoča nekaj načinov alternativne-ga zdravljenja pseudomonasnih okužb. Priporočljivo je kombinirati potentne antibiotike z ultrazvokom (akustična energija ultrazvoka povzroči poškodbe membran biofilma, kar omogoči dostop antibiotika do bakterijskih kolonij), električnim tokom nizke napetosti (elektromagnetni pulz poveča antimikrobno aktivnost kationskih antibiotikov proti biofilmu), bakteriofagi (ki proizvajajo encime s ka-terimi hidrolizirajo ekstracelularni matrix in omogočajo med drugim tudi lažji dostop antibiotikom), nano-nos-ilci (antibiotik inkapsulirajo v t.i. nano-nosilce, kot so na primer fosfotidil holin, polietilen glicerol, poliamidoamin in poliakrilat, ki antibiotik prinesejo na mesto delovanja



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in podaljšajo njegovo delovanje) in motenjem Quorum sensing-a (Abdullahi s sod., 2016). V nadaljevanju bom nekoliko podrobneje opisala zdravljenje z bakteriofagi in Quorum quenching.

Ideja zdravljenja bakterijskih bolezni s pomočjo bakte-riofagov sega v leto 1917. Kljub nekaj začetnim uspehom je bil ta način zdravljenja po 2. svetovni vojni, ko so se pojavili ceneni in učinkoviti antibiotiki, v zahodnem svetu opuščen. Še naprej pa so ta način zdravljenja uporabljali na Poljskem in na takratnem območju Sovjetske zveze (Pires s sod., 2015). Neracionalna raba antibiotikov pri zdrav-ljenju, še bolj pa množična uporaba antibiotikov v rejah ekonomskih živali z namenom doseganja večjega prirasta in proizvodnih učinkov je povzročila množični pojav bak-terij, odpornih na večino znanih antibiotikov. Med 25- 80% vseh antibiotikov, ki se dandanes uporabijo v ZDA, se uporabi v hrani proizvodnih živali v profilaktične namene in to v subterapevtskih odmerkih (Fair in Tor, 2014). An-tibiotiki za spodbujanje rasti so večinoma isti, kot jih upo-rabljamo za zdravljenje, prodajajo pa se celo izven lekarn in brez veterinarskega nadzora. V zadnjih nekaj letih ugo-tavljamo pojav enterobakterij, odpornih celo na karbap-enem, antibiotik, rezerviran za zdravljenje najtežjih okužb pri ljudeh (Jassim in Limoges, 2014). Z antibiotiki je vedno bolj obremenjeno tudi okolje, saj se kar 75% antibiotikov, ki jih prejmejo živali, ne presnovi v celoti (Chee-Sanford s sod., 2009). S polivanjem gnojnice se antibiotiki zanesejo v pitno vodo in ogrožajo zdravje ljudi (Jassim in Limoges, 2014). V ZDA profilaktična uporaba antibiotikov še vedno ni prepovedana, medtem ko je bila v Evropi ustavljena leta 2006 (Laxminarayan s sod., 2013).

Nastali položaj je pripeljal do iskanja alternativnih zdravljenj. Eno teh je zdravljenje z bakteriofagi. Bakte-riofagi so virusi, ki okužujejo bakterije. So približno 50 x manjši od bakterij (20-200 nm) in vsenavzoči v zemlji, vodi in številnih prehranskih izdelkih (meso, zelenjava, mlečni izdelki ipd.) (Ly-Chatain, 2014). Delimo jih na t.i. litične bakteriofage in lizogene bakteriofage. Ko litični bakteri-ofag okuži bakterijsko celico, se v njej razmnožuje mnogo hitreje, kot sama celica. Povzroči lizo celice in v okolico se sprostijo mladi bakteriofagi, ki okužijo sosednje bakterije. Lizogeni fagi pa se za razliko razmnožujejo tako, da se nji-hov genetski material vgradi v bakterijski genom in pravilo-ma celice ne ubijejo. Uporabimo jih lahko za vnašanje genov v bakterijski kromosom, s čimer lahko na primer restavriramo občutljivost bakterij na določene antibiotike. Zaenkrat se pri zdravljenju uporabljajo samo litični bakteri-ofagi (Jassim in Limoges, 2014; Ly-Chatain, 2014). Bakte-riofagi specifično okužijo tarčne bakterije in ne učinkujejo škodljivo na komenzale. Ne povzročajo alergij, poleg tega pa se odstranijo po naravni poti skupaj s popolno odstran-itvijo patogenih bakterij iz organizma. Lahko se uporabljajo v prehranski industriji, saj ne spreminjajo okusa, vonja ali strukture izdelkov (Ly-Chatain, 2014).

Prva kontrolirana klinična raziskava zdravljenja z bak-teriofagi v zahodnem svetu je bila narejena pri ljudeh s kroničnim otitisom, povzročenim z rezistentno bakterijo Pseudomonas aeruginosa (PA). Dvanajstim bolnikom so aplicirali mešanico bakteriofagov (Biophage-PA) v zu-nanji sluhovod in spremljali učinke zdravljenja 7., 21. in 42. dan po enkratnem vnosu. Ugotovili so statistično

značilno izboljšanje v primerjavi z dvanajstimi bolniki kon-trolne skupine, ki je prejela placebo. Neželenih stranskih učinkov niso beležili (Wright s sod., 2009). Samo leto kas-neje so v raziskavi pseudomonasnega otitisa pri psih ugo-tovili učinkovitost topikalnega nanosa bakteriofagov, ki je povzročil lizo bakterij brez toksičnih učinkov za organizem (Hawkins s sod., 2010). Ugotovljeno je, da je pri zdravljenju sistemskih okužb najučinkovitejši vnos bakteriofagov par-enteralni, medtem ko je oralni vnos predvsem učinkovit pri zdravljenju gastrointestinalnih okužb. Kot zelo učinkovito se je izkazalo lokalno zdravljenje (koža, sluhovodi, ustna votlina) kot tudi inhalacija bakteriofagov pri okužbah dihal (Ryan s sod., 2011).

Navdušujoča je hitrost tega načina zdravljenja. Pri psih s kroničnim pseudomonasnim otitisom, ki so prejeli eno samo aplikacijo koktejla šestih bakteriofagov v zunanji sluhovod, so v 48 urah zabeležili izboljšanje kliničnih zna-kov za 30% in zmanjšanje števila bakterij v izpirkih kar za 67% (Hawkins s sod., 2010). Pri psu z bilateralnim kroničnim pseudomonasnim otitisom so v samo 27. urah po aplikaciji bakteriofagov v zunanji sluhovod ugotovili odsotnost znakov vnetja in vlage v zdravljenem sluhovodu (Pires s sod., 2015).

Danes poznamo že okrog 140 bakteriofagov, ki na-padajo PA. Izolirali so jih iz različnih okolij, največ iz fekalij, vključno z bolnišničnimi odplakami. Prihodnost pridobivan-ja bakteriofagov pa se kaže v sintetično proizvedenih sevih, kar je mnogo cenejše od pridobivanja iz naravnega okolja (Pires s sod., 2015). V zadnjih desetih letih so že bili proizve-deni in registrirani komercialni proizvodi (na primer Listex© v sirarski industriji, Listshield©, Ecoshield ©, Salmonelex© in drugi za uporabo v prehranski industriji). BioPhage-PA (AmpliPhi biosciences corp., UK) je komercialna mešanica fagov, ki jih uporabljajo za zdravljenje kroničnega otitisa, povzročenega s Pseudomonas aeruginosa. Sicer pa je uspešnost zdravljenja s pomočjo bakteriofagov odvisna od številnih dejavnikov, kot so na primer razmerje števila bak-teriofagov proti številu bakterij, pH in temperatura medija, v katerem zdravilo deluje ipd. Negativno lahko vpliva rez-istenca bakterij proti fagom in nevtralizacije fagov s strani imunskega sistema. Na splošno fagi ne preživijo padca pH pod 4,5 in jih v veliki meri nevtralizira želodčna kislina, so pa precej odporni proti izsuševanju in visokim tempera-turam (40-90°C) in nekateri preživijo celo pasterizacijo. Vprašljivo je njihovo delovanje proti intracelularnim bak-terijam (kot je na primer Salmonela) (Ly-Chatain, 2014).

Alternativni način zdravljenja pseudomonasnih okužb je tudi poseganje v Quorum sensing (QS). Izraz QS označuje komunikacijo med bakterijami v koloniji, s pomočjo katere se posamezne bakterije v koloniji začnejo obnašati kolektiv-no. Pseudomonas aeruginosa v koloniji proizvaja signalne molekule, imenovane N-acilhomoserin laktoni (AHL). S pomočjo teh molekul bakterija v kolonijah ureja virulenco in druge dejavnike, pomembne za uspešno okužbo, saj se kolonija na določeno koncentracijo teh molekul kolektivno odzove. Učinkovito se bakterije odzovejo s proizvodnja biofilma, ki kolonijo zaščiti tako pred imunskim sistemom organizma kot pred antibiotiki. Zaprti sistemi, kamor sodi tudi vnetje zunanjega sluhovoda, so za proizvodnjo biofil-ma in razvoj kronične okužbe še posebej ugodni. V raziska-vi, nedavno narejeni na VF v Ljubljani, smo dokazali pris-



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otnost molekul AHL v vsebini sluhovodov psov, okuženih s PA (Kušar s sod., 2016). Poleg tega smo ugotavljali tudi možnost zdravljenja, ki ga imenujemo Quorum quenching (QQ). V principu poteka zdravljenje tako, da z določenimi zdravili motimo QS in na ta način onemogočamo kolektiv-no komunikacijo med celicami v koloniji, ki tako postanejo manj odporne na delovanje antibiotikov. V naši raziskavi smo uporabili antibiotik azitromicin. Na ta antibiotik je PA sicer odporen vendar smo ugotavljali zdravilne učinke azitromicina kot motilca izločanja molekul AHL v koloniji bakterij. Ugotovili smo sicer le šibko tendenco k hitrejši eliminaciji PA ob sočasnem zdravljenju z azitromicinom in antibiotiki, vendar je možen vzrok za rezultat premajhno število psov, vključenih v raziskavo (Vengušt s sod., 2015).

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