Bacteria of Ophthalmic Importance Diane Hendrix, DVM, DACVO Professor of Ophthalmology

Bacteria of Ophthalmic Importance Diane Hendrix, DVM, DACVO Professor of Ophthalmology

THE UNIVERSITY OF TENNESSEE COLLEGE OF VETERINARY MEDICINE DEPARTMENT OF <>

1 Bacteria

Prokaryotic organisms – cell membrane – cytoplasm – RNA – DNA – often a cell wall – +/- specialized surface structures such as capsules or pili.

–lack a nuclear membrane or mitotic apparatus – the DNA is organized into a single circular chromosome

www.norcalblogs.com/.../GeneralBacteria.jpg

2 Bacteria

+/- smaller molecules of DNA termed plasmids that carry information for drug resistance or code for toxins that can affect host cellular functions

www.fairscience.org

3 Variable physical characteristics

• Mycoplasma lacks a rigid cell wall • Borrelia and Leptospira have flexible thin walls. • Pili are short, hair-like extensions at the cell membrane that mediate adhesion to specific surfaces.

http://www.stopcattlepinkeye.com/about-cattle-pinkeye.asp

4 Bacteria reproduction

• Asexual binary fission • The bacterial growth cycle includes: – the lag phase – the logarithmic growth phase – the stationary growth phase – the decline phase • Iron is essential for bacteria

5 Opportunistic bacteria • Staphylococcus epidermidis • Bacillus sp. • Corynebacterium sp. • Escherichia coli • Klebsiella sp. • Enterobacter sp. • Serratia sp. • Pseudomonas sp. (other than P aeruginosa).

6 Infectivity

• Adhesins are protein determinates of adherence. Some are expressed in bacterial pili or fimbriae. • Flagella • Proteases, elastases, hemolysins, cytoxins degrade BM and extracellular matrix. • Secretomes and lipopolysaccharide core biosynthetic genes inhibit corneal epithelial cell migration

7 8 Normal bacterial and fungal flora Bacteria can be cultured from 50 to 90% of normal dogs. – Gram + aerobes are most common. – Gram - bacteria have been recovered from 8% of normal dogs. – Anaerobes are rarely isolated. Normal flora varies with the season and the breed of dog. Fungi have been isolated from 22% of dogs in one study.

9 Conjunctival flora in dogs with ulcerative keratitis. • Bacteria are more commonly isolated. • Malassezia pachydermatitis is present in 23% of eyes with corneal ulceration

10 Equine flora

Normal bacterial flora Corynebacterium spp., beta-hemolytic Streptococcus, Staphylococcus spp., Klebsiella spp., Bacillus cereus and Moraxella spp. Fungal flora Unidentifiable molds, dematiaceous molds, Chrysosporuim spp., Cladosporium spp., Aspergillus spp. and Penicillium spp.

11 Bovine flora

• Cladosporium spp. and Penicillium spp. • No seasonal or housing difference. • May represent transient seeding from the environment, including the hay, as suspected in other species.

12 Normal flora •Bats • Alpacas • Chelonians

13 www.biology4kids.com Staphylococcus spp.

• Ubiquitous and are part of the microflora of the skin and mucous membranes. • Gram + organisms that appear cytologically as individuals, pairs, small groups or grapelike clusters. • Facultative anaerobes and fermentative. • Isolates commonly recovered from ocular sources are coagulase-positive species.

14 Infectious Keratitis

– S aureus is isolated from about 5% of horses – S intermedius is isolated from 2% of horses and 29% of dogs – Coagulase-negative species include S epidermidis (isolated from 6% of affected horses).

15 Resistance

• Canine isolates are sensitive to cefazolin, ciprofloxacin, and chloramphenicol. • Of 4 equine isolates all were sensitive to bacitracin, chloramphenicol, neomycin, and enrofloxacin. upload.wikimedia.org

16 Streptococcus spp. and related cocci

• Ubiquitous, suppurative bacteria • Enterococci are opportunists • Streptococcal keratitis is relatively common

17 • β-hemolytic Strep spp - 17% of dogs • S. equi subsp zoo - 12% and 22% of the isolates from horses.

18 Streptococcus spp.

UT – Equine and canine • all isolates were susceptible to ciprofloxacin, cephalothin and chloramphenicol • > 80% resistance to neomycin, polymixin B and tobramycin UF - Equine • All susceptible to chloramphenicol, bacitracin • An increase in resistance of S.equi subsp zooepidemicus to gentamicin was found over time Australia >80% of isolates were resistant to ciprofloxacin but remained susceptible to chloramphenicol and cephalexin

19 Streptococcus spp. Strangles

• Streptococcus equi subsp. equi • Transmission via direct contact and fomites • Colonizes within the pharyngeal and nasal mucosa Signs – Lymphadenopathy –Pyrexia – Malaise – Purulent discharge – Pharyngitis – Abscessed lymph nodes

20 Streptococcus spp. Bastard strangles • Cases involving any area other than the pharyngeal area. • Ocular abnormalities – Serous then mucopurulent discharge – Panophthalmitis – Chorioretinitis – Central blindness • Dx via culture or PCR

21 Corynebacterium spp.

• Gram + rods • Appear singly or in pairs • +/- clubbed ends • Flora of normal skin and mucous membranes

22 Bacillus spp.

• Gram + rods found singly, in pairs or chains. • May have a single endospore • More pathogenic organisms usually present as co-infections. • Most common organism isolated from endophthalmitis in humans.

http://content.answers.com/main/content/wp/en-commons/thumb/4/42/260px-Bacillus_subtilis_Spore.jpg

23 Listeriosis • Rod-shaped, Gram + bacterium • L monocytogenes most common in animals • Spoiled or incompletely fermented corn or hay silage is the main source of infection in outbreaks.

VCNA Food AnimPract. 2010 Nov;26(3):487-503

24 • CNS disease is most likely to be associated with ocular signs in food animal species. – vestibular ataxia – cranial nerve deficits – brain stem involvement • facial nerve paralysis •KCS • Keratitis • Anterior uveitis w/hypopyon • Purulent endophthalmitis

VCNA Food AnimPract. 2010 Nov;26(3):487-503

25 Other species •Dog • Conjunctivitis, neurologic signs, and pancytopenia with generalized infection. • Sheep & goats – Scleral hyperemia – Unilateral keratitis +/- ulceration – CNS signs

en.wikipedia.org/wiki/Listeriosis_in_animals

26 Pseudomonas spp. • Gram - rods • Widely distributed. • Found in the skin and mucous membranes. • Cytologically indistinguishable from other rods • Antibiotic susceptibility testing is especially important

27 Pseudomonas aeruginosa • Isolated from about 15% of horses with bacterial keratitis • Isolated from 21% of dogs

28 Innate resistance

Evans 2013

29 Pathogenic mechanisms

sciencephoto.com www.cdc.gov www.asylumresearch.co.uk/.../Bacteria/Cell!.jpg

30 Pathogenic mechanisms of Pseudomonas aeruginosa Major matrix metalloproteinases

Alkaline protease – attacks the helical structure of native type I, III, IV collagen – interferes with host defense systems by degrading complement components, IG, IFN, IL 1 and 2, and tumor necrosis factor. Elastase • As above • Activates proMMPs MucD

31 Pathogenic mechanisms of Pseudomonas aeruginosa Cytotoxic and invasive strains • Cytotoxic strains remain mostly extracellular • Invasive strains enter cells and replicate within them. • Tobramycin vs ofloxacin •Steroids? • Both antibiotics hastened disease resolution infections caused by either strain.

32 IOVS 2011 March; 52(3): 1368–1377

33 Pseudomonas aeruginosa Resistance • Almost all isolates are sensitive to gentamicin, tobramycin, and ciprofloxacin • Study with 7 fluoroquinolones • 24/ 27 isolates were susceptible to all fluoroquinolones evaluated • Susceptibility ranged from 88.9% to 100% • No significant differences among isolate susceptibilities to the individual antimicrobials or among generations of fluoroquinolones

34 Multi-drug resistant, extensively drug resistant, and pan-drug resistant strains of P aeruginosa

• Risk factors: bandage contact lens, topical steroids, previous therapeutic graft, preservative-free lubricant ointment and ocular surface disorders. • Of 15 isolates, one isolate was resistant to all antibiotics. • Success with medical therapy alone was not common. These cases are more likely to require the use of tissue adhesives and keratoplasty and are likely to have treatment failure. • Another study compared the efficacy of topical 1.5% and 0.5% levofloxacin.

35 Bacteriophages/ Pseudomonas aeruginosa Predatory Prokaryotes

AJVR 2011 Aug;72(8):1079-86

36 • 6 year old Quarter horse gelding • Tearing couple days previously • RDVM started neo/poly/dex

37 38 39 • Cytology – many PMNs • Treatment: – Lavage – Serum q2h – Tobramycin q2h – Cefazolin q2h – Miconazole q2h – Atropine QID – Flunixin 500 mg PO BID

40 • 4 colonies of P. aeruginosa

41 Day 4

42 Discharged on day 7 • Serum and antibiotics 5x/day • Atropine BID • Flunixin 500 mg PO QD

• Day 10 - Discontinued miconazole • Day 14 – Discontinued serum, atropine to SID

43 Day 20

44 Day 30

45 Day 45

46 Moraxella spp.

• A large, plump, Gram - coccobacillus • Primary cause of infectious bovine keratoconjunctivitis (IBK) “pinkeye” • Highly contagious ocular infection of cattle Monetary losses caused by:

– decreased weight gain

– decreased milk production

– devaluation because of eye disfigurement

– cost of treatment

47 Moraxella bovis Transmission

• Opportunistic pathogen • Environmental factors – Exposure to UV light – Irritants- face fly • Host factors – Genetic – Nutritional – Immune status – Current infections

48 Transmission of Moraxella bovis

Nonpiliated, nonpathogenic forms can exist in a carrier state in the host. • Carrier animals are asymptomatic, but shed the organism. • Harbored in nasal, ocular, and vaginal secretions Transmitted by direct contact, aerosol, or fomites. Cattle are the primary natural reservoir for M bovis and have a high nasal carrier rate.

49 Transmission of Moraxella bovis

The face fly Musca autumnalis is a primary mechanical vector and serves as an irritant.

www.forestryimages.org bugguide.net popgen.unimaas.nl

50 Transmission of Moraxella bovis

• UV light causes direct conversion of nonhemolytic, nonpiliated organisms to pathogenic forms in carrier animals. • Then a rapid logarithmic growth phase of the organism begins.

51 Transmission of Moraxella bovis

• Bos taurus is more susceptible to IBK than is Bos indicus (such as Zebu and Brahman) • Calves are more prone to disease than adults. • IBK is more common in summer and fall

52 Pathogenesis of Moraxella bovis - Pili

M. bovis attaches to undamaged older, hypermature corneal epithelial cells with smaller, more densely packed microvili. Two kinds of pili – Q-pili are specific for colonization of the bovine corneal epithelium – I-pili enable maintenance of an established infection.

– Pili alone cannot cause diseasewww.hgsc.bcm.tmc. edu/projects/microbial/Mbovis

53 Pathogenesis of Moraxella bovis

β-hemolysin of M bovis is also required to cause disease. – RTX family of toxins – causes clinical signs directly as a result of damaged ocular cells or indirectly through lysis of the WBCs attracted to the site.

54 ns causedns 1987; 24(4):287-295. 1987; Vet Path Vet in gnotobiotic calves. gnotobiotic in Moraxella bovis Moraxella by Rogers DG, Cheville NF, Pugh GWJ. Pathogenesis of corneal lesio corneal of Pathogenesis GWJ. Pugh NF, Cheville DG, Rogers

55 Moraxella bovis Pink eye – Infectious Bovine Keratitis

• Summer and fall • Younger cattle • Incubation period 2-3 days.

56 Moraxella bovis Clinical Signs

Initially – Decreased appetite – Moderate pyrexia. – Epiphora – Blepharospasm – Chemosis and hyperemia of the conjunctiva Day 2 – A small opaque area appears axially Day 6 – Entire cornea is gray-white to yellow with axial corneal ulceration – +/- corneal vascularization

57 Moraxella bovis Outcome

Typically – Complete recovery in 3-5 weeks – Some with persistent scar Infrequent outcomes – Severe ulceration – Corneal rupture with iris prolapse – Conical bulging of the eye – Blindness

58 Moraxella bovis Treatment - Parenteral

• Oxytetracycline (LA200 2 injections, 20 mg/kg IM at 72 hour intervals) • Oxytetracycline (Tetradur, 300 mg/ml, 1-2 ml IM, lasts 7-10 days.) • Florfenicol (2 IM dosages of 20 mg/kg 48 hours apart or a single 40 mg/kg SC dosage)

59 Moraxella bovis

Treatment - Subconjunctival

• Procaine penicillin (1-2 ml) +/- subconjunctival dexamethasone (1-2 ml) • Oxytetracycline (100 mg/ml subconjunctival 1-2 ml)

60 Moraxella bovis Treatment

• Nictitating membrane flaps or temporary tarsorrhaphies • Decreasing the fly population • Decreasing UV radiation • Autogenous vaccines • Cytokines with inactivated bacteria • Intranasal vaccines

61 Moraxella bovoculi

• Isolated from IBK cases • Blepharitis and conjunctivitis • Respond to IBK treatments • Association with M bovis?

62 Other diseases by Moraxella spp. • Moraxella spp. cause other ocular infections of small ruminants and horses. • Moraxella ovis – Gram - diplococcus – Cultured from normal small ruminants – Cultured from sheep and goats with keratoconjunctivitis. – May occur as a co-infection with chlamydial or mycoplasmal conjunctivitis – May complicate other ocular diseases

63 Pasteurellosis

• Pasteurella multocida • Very small, non-motile, Gram - ovoid, coccoid or short rod

• Bipolar staining http://www.med.monash.edu.au/microbiology/staff/adler/ • Aerobic and facultatively anaerobic

64 Pasteurellosis Opportunistic bacteria

Virulent factors –endotoxin –adhesins –filamentous appendages help P. multocida colonize mucous membranes

65 Pasteurellosis Clinical signs in rabbits • Rhinitis (or snuffles) • Pneumonia • Genital infections • Wound infections • Abscesses www.mri.sari.ac.uk/%5Cjpg%5Cbact-rep10-fig2b.jpg • Otitis media

66 Pasteurellosis Ocular signs • Conjunctivitis • Dacryocystitis – mucopurulent discharge – pressure below the medial canthus expresses purulent material – lacrimal sac may be distended – secondary conjunctivitis and keratitis

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/171317.htm

67 Brucellosis

• Brucella canis • Zoonotic aerobic Gram-coccobacillus • Survives in mononuclear cells. • Penetrates mucous membranes. • Ingestion and venereal transmission are common. • Can be transmitted via fomites, such as cages or equipment.

68 Brucellosis Ocular signs

• Occur in ~ 14 % of dogs with brucellosis. • Endophthalmitis • Chronic uveitis • Hyphema • Chorioretinitis

69 Brucellosis Systemic signs

• Diskospondylitis • Glomerulopathy • Meningoencephalitis • Abortion and infertility are common in breeding dogs • Dogs not used for breeding may have undetected disease for long periods of time due to the prolonged bacteremia and secondary localization

70 Brucellosis Diagnosis • Isolation and identification • Serologic screening involves the rapid slide agglutination test with and without 2-mercaptoethanol. • Tube agglutination, ELISA or IFA tests or the cytoplasmic protein agar gel immunodiffusion test have greater specificity • Zoonotic potential

71 Brucellosis Case Report • 3 neutered dogs • Chronic recurrent uveitis • Blood culture or PCR • Responded to therapy

Vet Ophthalmol. 2009 May-Jun;12(3):183-91.

72 Histophilus spp.

• Histophilus spp. requires factors from blood for growth. • Normal flora of the oral cavity and nasopharynx • Also primary etiology for acute mucopurulent conjunctivitis in humans. • Little affinity for the avascular cornea, and corneal involvement is a rare complication of conjunctivitis.

73 Thromboembolic Meningoencephalitis Histophilus somnus Acute septic TEME most commonly occurs in feedlot cattle

Can Vet J. 1971 September; 12(9): 180–182.

74 Mycoplasma

• Smallest prokaryotic cells capable of self-replication • Ubiquitous free-living saprophytes (eg. members of the Genus Acholeplasma) • Animal pathogens include the genera Mycoplasma and Ureaplasma

75 Mycoplasma

Lack a true cell wall, but have a plasma membrane. – accounts for their plasticity and pleomorphism, including cocci, spiral filament, and ring-like

http://www.malp-research.de/malp_history.html, webmedia.unmc.edu/.../2SL31-mycoplasma.jpgstructures

76 Mycoplasma

• stain poorly with Gram stain • Giemsa and other Romanowsky stains are better • fragility, pleomorphism and weak staining characteristics make direct examination of stained smears of limited value in making a diagnosis

Vet Clin Pathol 41/2 (2012) 283–290

77 Mycoplasma Pathogenesis • Adhere to host mucous membranes where they remain extracellular • Produce – hemolysins – proteases – nucleases – other toxic factors • Latency can occur •Host specific • Eye infections are characterized by serous discharge and conjunctival hyperemia

78 Mycoplasma M. felis, M. gateae, M. arginini and Acholeplasma laidlawii Cats • Recovered from the eyes of cats with ocular disease • Also recovered from the normal conjunctiva • Koch’s postulates have not been fulfilled with these organisms with the exception of M. felis. • Inoculating kittens with M. felis causes clinical signs • It is more commonly cultured from ill cats versus normal cats • Clinical signs

79 M conjunctivae and M agalactiae

Sheep • keratoconjunctivitis (with corneal vascularization but not corneal ulcers) Goats (and maybe sheep) • M. agalactiae causes systemic disease including arthritis, mastitis or abortion • M. mycoides subsp. mycoides (large- colony type) causes septicemia, mastitis, and arthritis

80 Ophthalmic signs in sheep and goats

Mycoplasma – keratoconjunctivitis – anterior uveitis – choroiditis – hyalitis • M. mycoides in goats – keratoconjuctivitis with perilimbal corneal opacities – eye lesions may occur without systemic signs

81 M. bovoculi, Ureaplasma spp., M. laidlawii and M. bovirhinis

Cattle • bovine conjunctivitis • association with M bovis has not been confirmed. • tends to occur in the summer • mild and self-limiting

82 Mycoplasma Mycoplasma bovis Cattle – Pneumonia – Arthritis – Mastitis – Meningitis – Infertility – Subcutaneous abscesses in cattle – Keratoconjunctivitis

83 Chlamydophila sp. (Chlamydiae) • Obligate intracellular organisms • Cell walls similar to those of other Gram- bacteria • Lack the machinery that allow autonomous survival and replication

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/201700.htm

84 • The cell replication cycle involves: – Extracellular (elementary body) Chlamydophila psittaci

• 0.2-0.6 µm in size la_pneumoniae.jpg/200px-Chlamydophila_pneumoniae.jpg

with rigid cell walls Elementary bodies of – Intracellular

(initial body, reticulate body) liver, hematoxylin hepatocytes (Parrot,in the cytoplasmof )a nd eosin stain).

• 0.5 – 1.5 µm Chlamydia psittaci www.vet.uga.edu/.../turnerandrobbins/Fig1.jpgFigure1. http://upload.wikimedia.org/wikipedia/en/thumb/1/1a/Chlamydophi lack cell walls (previously

85 • Previously all members of the family Chlamydiaceae were known as one species Chlamydia psittaci • Currently there are 2 genera, Chlamydia and Chlamydophila, and multiple species within each

86 Chlamydophila felis • Transmission – direct contact or aerosols. • Only survives a few days in the environment. • Cellular and hormonal mechanisms play a role in immunity. • Cats under < 8 weeks and > 5 years are unlikely to become infected. • In general chlamydiae are considered to have a restricted host range.

87 Chlamydophila felis Pathogensis

• Highly contagious • Spreads rapidly by direct contact • A low dose incites unilateral disease and a high dose incites bilateral disease. • Spread internally to colonize many tissues including the tonsil, lung, liver, spleen and kidney. • Shed in the tears and nasal secretions • May persist in the ocular tissues for months following remission of ocular signs.

88 Chlamydophila felis Clinical signs

• initial chemosis • suppurative conjunctivitis • petechial hemorrhages • conjunctival lymphoid follicles • +/- respiratory signs

89 Chlamydophila felis Clinical signs

• Experimental infection • unilateral conjunctivitis within 5-10 days of exposure • Serous ocular discharge becomes mucoid or mucopurulent within 3-5 days • Cats that become bilaterally affected have clinical signs persist for 22-25 days. • Recovery can result in persistent infections with conjunctival shedding for up to 8 months. • Chronic shedding of organisms from the urogenital and GI tract has been documented.

90 Microb Pathog. 2016 Aug;97: 14-8

91 Chlamydophila felis Diagnosis

• C. felis, in contrast to Chlamydial infections in other species, is not associated with keratitis. • Isolation from conjunctival cotton swabs (without wooden sticks) •ELISA •PCR •FA • Intracytoplasmic elementary bodies

Vet Clin Pathol 41/2 (2012) 283–290

92 Chlamydophila felis Treatment

• Changes to facility management • Topical oxytetracycline QID for 2 weeks past resolution of clinical signs • Erythromycin and chloramphenicol are also effective • Pradofloxacin vs doxycycline

93 Disease in Farm Animals

• Chlamydophila pecorum • Chlamydophila abortus • Chlamydia suis

94 C. pecorum

• Cattle, sheep and swine • Encephalomyelitis • Enteritis • Polyarthritis •Metritis • Pneumonia • Conjunctivitis • Typically young animals are affected in sporadic outbreaks.

95 C. abortus C. abortus

• Sheep – Conjunctivitis – Keratitis – Polyarthritis – Pneumonia –Orchitis – Epididymitis – Abortion • Chlamyodophilosis among lambs and kids may produce both ocular signs and polyarthritis.

96 C. abortus Ocular signs • Bilateral in 80% • Conjunctiva lesions – Conjunctivitis – Petechial hemorrhages – Epiphora and purulent exudation – Lymphoid follicle proliferation (which may become confluent, producing folds) • Cornea – Peripheral edema and neovascularization – Ulceration is rare

97 C. abortus Treatment

• Topical oxytetracycline is used to treat lambs and kids • LA200 is effective • Usually self limiting in 2-3 weeks.

98 C. abortus • Diagnosis

– Conjunctival cytology

–Culture

–ELISA

– PCR

• Persistent infection with intermittent shedding is common among ovine chlamydial diseases.

• The elementary bodies are relatively resistant and may remain viable for several days.

99 C suis

Swine • Conjunctivitis • Keratoconjunctivitis • Enteritis • Pneumonia • Lymphofollicular hyperplasia of the palpebral conjunctiva • Isolated from the conjunctiva of healthy pigs. Journal of Zoo and Wildlife Medicine 44(1): 159–162, 2013

100 Chlamydophila psittaci

• Avian chlamydiosis • Subclinical, acute, subacute, or chronic infection • Worldwide at least 150 avian species • Respiratory, digestive, or systemic infection. • 10-30% of surveyed avian populations may be found positive. • Avian serotypes are capable of infecting people and other mammals.

101 Chlamydophila psittaci Transmission • Airborne elementary bodies are resistant to drying. • Also spread by fecal oral transmission. • Stress can initiate shedding and cause recurrence. • Carriers can shed the organism for extended periods. • The incubation is typically 3-10 days.

102 Chlamydophila psittaci Clinical signs

• Nasal and ocular discharge • Conjunctivitis • Sinusitis • Green to yellow-green droppings • Fever • Inactivity • Ruffled feathers • Weakness • Inappetence, and weight loss • Asymptomatic infections are common

103 Chlamydophila psittaci

Diagnostics www.vet.uga.edu/vpp/clerk/Bockino/Fig1.jpg

• clinical findings • hematology • clinical chemistries • radiology • organism can be seen in impression smears of affected tissues stained by Giemsa, Gimenez, or Macchiavello’s method. • IFA, ELISA, PCR

104 Disease in Koalas • keratoconjunctivitis • urinary tract disease • reproductive tract disease • rhinitis/pneumonia

Veterinary Microbiology 165 (2013) 214–223

105 Treatment • Response to treatment is variable • Decreased palpebral fissure, entropion and corneal scarring may result. • Enrofloxacin, chloramphenicol • Not tetracyclines and macrolides

106 Bartonella • Gram-negative

• Facultative intracellular rod or coccobacillus

• Bartonellaceae family • Transmitted by arthropods • Infection is suspected to be primarily in RBCs, but infection of vascular endothelium also occurs.

107 Bartonella In Cats

• Bartonella henselae is the most frequently reported species to infect cats • Naturally occurring infection is mild and transient • Clinical findings: pyrexia, lymphadenopathy, lethargy, anorexia, CNS disorders, urologic diseases and endocarditis • Ocular disease: uveitis, keratitis and chorioretinitis

108 Bartonella Diagnosis in cats • Serology • Blood culture •PCR • In the United States, 12-67% of the cats are seropositive for Bartonella. • A higher prevalence of affected cats occurs in warm, humid areas which have more fleas.

109 Neonatal septicemia/bacteremia

Commonly isolated bacteria in foals – E. coli – Klebsiella spp – Actinobacillus spp – Enterobacter spp – Pseudomonas spp – Rhodococcus equi

110 Neonatal septicemia/bacteremia In foals Routes of entry for bacteria – Placenta, umbilicus, lungs & GI tract. The major risk factor for septicemia is failure of passive transfer of colostral antibodies. Other factors include – unsanitary environmental conditions – gestational age of the foal (prematurity) – health and condition of the mare – difficulty of parturition – new pathogens in the environment

111 Neonatal septicemia/bacteremia

Frequently affected organ systems – Umbilical remnants – CNS – Respiratory – Cardiovascular – Musculoskeletal – Renal – Hepatobiliary – GI organs • Depressed and lethargic. The foals do not nurse with normal frequency.

112 Neonatal septicemia/bacteremia Ophthalmic findings

• Fibrin in the anterior chamber • Hypopyon • Severe miosis • Entropion (if the foal is dehydrated)

113 Neonatal septicemia/bacteremia Commonly isolated bacteria in farm animals – E coli – Klebsiella spp – Actinobacillus spp – Streptococcus spp – Arcanobacterium pyogenes – Salmonella spp – Pasteurella spp

114 Neonatal septicemia/bacteremia Disease in farm animals

• Calves, piglets, kids and lambs • Umbilical infections or ingesting bacteria. • Clinical signs include polyarthritis, meningitis and/or diarrhea. • Ocular lesions: fibrin clots in the AC, hypopyon or hyphema, miosis, and chorioretinal embolic lesions

115 Anaerobic Pathogens

• Anaerobic bacteria possess complex species-dependent virulent mechanisms. • Direct corneal damage – Elaboration of toxins, metabolites, enzymes, and degradation products • Indirect corneal damage – Stimulation of corneal immune responses.

116 Anaerobic Bacteria

• Isolated from dogs, cats, horses and alpacas with ulcerative keratitis. • Isolated from 13% of corneal samples. • Genera Clostridium, Peptostreptococcus, Actinomyces, Fusobacterium, and Bacteroides. • Positive correlation between isolation and ocular trauma, preexisting corneal disease and chronic dermatologic disease.

117 Anaerobic Pathogens

• Concurrent or prior facultative aerobic bacterial multiplication • Aerobic bacteria may also produce essential nutrients, growth factors, energy substrates and protective enzymes. • Mixed infections provide mutual protection from phagocytosis and intracellular killing.

118 Anaerobic Pathogens

• Most antimicrobials have limited to no microbial action against anaerobic pathogens. • Antimicrobial susceptibility patterns are relatively predictable (except Bacteriodes spp.) • Elimination of synergistic aerobic bacteria and disruption of low oxygen corneal microenvironment may be mechanism.

119 Anaerobic Pathogens

• Stromal abscess in a dog. • Implicated in necrotic and suppurative deep tissue infections • Often mixed infections with facultatively anaerobic bacteria

120 Other Bacterial Infections

• Rickettsia • Ehrlichia • Borrelia • Leptospira

121 Rickettsial species • minute, obligate intracellular bacteria • transmitted by ticks • rod-shaped or coccobacilli • 0.3 to 0.6 µm in length • contain both RNA and DNA • replicate primarily within the cytosol of target cells. • nonmotile • aerobic

•users.wfu.edu/derkls4/images/attachment%20of%...

122 Rocky Mountain Spotted Fever

• R rickettsii • An acute febrile illness in dogs and humans. • USA, Western Canada and Central and South America.

123 Rocky Mountain Spotted Fever

• Tick vectors are D variabilis and D andersoni. • Methods for tick infection • Transmission does not occur for 5-20 hours post attachment

stri.discoverlife.org/IM/I_GA/0000/640/Dermac...

124 Rocky Mountain Spotted Fever Pathogenesis • Vasculitis is the primary lesion • Pathogenesis – relates directly to the vascular lesions which initiate platelet activation and activation of the coagulation system.

125 Rocky Mountain Spotted Fever Clinical signs in dogs – Fever – Neurologic dysfunction – Polyarthritis – Petechial and ecchymotic hemorrhages – Thrombocytopenia – Nonregenerative anemia • Signs begin within 3 days of tick attachment. • Hemorrhages most commonly occur on mucous membranes, but epistaxis, melena and hematuria may be present in severely affected animals.

126 Rocky Mountain Spotted Fever Ocular signs • Altered vascular permeability in the conjunctiva, uvea, and retina results in ocular signs.

127 Rocky Mountain Spotted Fever

Conjunctivitis – conjunctivitis – chemosis – petechial hemorrhages – mucopurulent to purulent ocular discharge Anterior segment – iris stromal petechiations – anterior uveitis – hyphema

128 Rocky Mountain Spotted Fever

• Posterior segment – retinitis characterized by perivasculitis, focal areas of edema, and petechiation. – Unilateral or bilateral optic neuritis • Ocular disease may be confined to the retina • Ophthalmic lesions are usually mild

129 Rocky Mountain Spotted Fever

130 Rocky Mountain Spotted Fever Experimental infection Fluorescein angiography • ↑permeability in retinal vessels beginning 6 days post infection and 2 days after onset of pyrexia. • Venules are more permeable than arterioles

131 Rocky Mountain Spotted Fever Histopathology • Necrotizing vasculitis with perivascular accumulations of PMNs and lymphoreticular cells. • Organs with endarterial circulation such as skin, brain, heart, kidney and retina are affected.

132 Rocky Mountain Spotted Fever Diagnosis

• rising serum titers on micro IFA test •isolation www.cdc.gov/ncidod/dvrd/rmsf/IMAGES/rick-IFA.jpg • www.answers.com/.../rocky-mountain-spotted-fever

133 Rocky Mountain Spotted Fever Treatment • Doxycycline • Tetracycline • Chloramphenicol • Enrofloxacin • 14-21 days is usually effective • +/- inflammatory doses of oral prednisone in conjunction with antibiotic therapy.

134 Ehrlichia canis

• Causes canine monocytic ehrlichiosis • Acute, subclinical and chronic disease. • Gram - bacteria • Lack peptidoglycan and lipopolysaccharide components.

135 E. canis Transmission • Obligate intracellular parasite transmitted by the brown dog tick, Rhipicephalus sanguineus. • The tick can transmit the disease more than 5 months after detaching from the canine host.

136 E. canis Pathogenesis

• Replicates in mononuclear inflammatory cells and circulating leukocytes • As perivascular tissues become infected, severe vasculitis may occur, resulting in bleeding and platelet consumption. • The morulae, which are cytoplasmic clusters of dividing organisms, can be seen microscopically in monocytes.

137 E. canis Disease in dogs

• Acute phase occurs 8-20 days post infection and lasts 2-4 weeks. • Common clinical signs include – fever and depression – +/- neurologic signs – petechial and ecchymotic hemorrhages, epistaxis – lymphadenopathy – limb edema – vomiting • Ticks are found on 40% of dogs.

138 E. canis Subclinical phase

• The subclinical phase lasts for weeks to months. • Clinical signs may regress.

139 E. canis Chronic phase

• May persist for years • Signs may include: – depression – weight loss – pale mucous membranes – abdominal tenderness – bleeding episodes – secondary infections – limb edema

140 E. canis

Ocular signs • Associated with:

– acute vasculitis

– perivasculitis

– thrombocytopenia

– platelet dysfunction

– hyperviscosity

141 E. canis

Ocular signs • Conjunctival hyperemia and hemorrhages • Corneal edema • Deep corneal vascularization • Anterior uveitis • Chorioretinitis • Panuveitis • Optic neuritis

142 E. canis

Chronic ocular signs

• hyperproteinemia and hyperviscosity syndrome lead to retinal vascular engorgement

143 E. canis

Diagnosis • Laboratory abnormalities • Presence of morula on stained blood smears • Bone marrow cytology with hypoplastic elements, plasmacytosis, and mastocytosis • IFA and PCR

144 E. canis Histopathology of E. canis • The most consistent histopathologic finding is a predominantly monocytic or lymphocytic cell infiltrate of the uveal tract, retina and optic nerve.

145 • 5 year old male castrated Aussie • Presented for lethargy, fever, tachypnea, and stiff gate • A tick was noted 3 days earlier • Temp: 103.7 Pulse: 130 Respiration: 42 • No oral petechia or ecchymosis noted • No joint swelling or effusion

146 147 • Thrombocytopenic 120,000 • RMSF titer was <1:16 at presentation and 1:128 2 weeks later.

• DISCHARGE INSTRUCTIONS: Doxycycline (100 mg): Give 1 tablet by mouth every12 hours for three weeks.

148 Borreliosis or Lyme’s Disease • Tick-borne spirochetosis • Borrelia burgdorferi • Small corkscrew shaped motile microaerophilic bacteria. • Do not survive free living in the environment. • Highest incidence of disease remains in the www.medicalecology.org/diseases/lyme/em.jpg northeastern US.

149 Transmission of B. burgdorferi

• Ticks of the Ixodes sp. • Primary reservoirs are small rodents and birds. • Transmission relates to contact time of the tick on the host – 48 to 72 hours for a 38-92% transmission rate.

www.cdc.gov/.../images/TickMaster4_12_w452.gif

150 Borreliosis Pathogenesis

• Once inside the host, the organisms use their specialized endoflagella to move through the connective tissues. • Organisms can survive for years in skin, connective tissue, joints and nervous system.

151 Borreliosis Disease in dogs and cats

• Systemic signs in dogs and cats include lameness, joint pain, pyrexia and lymphadenopathy. • Ocular lesions include conjunctivitis, corneal edema, anterior uveitis, retinal petechia, chorioretinitis, and retinal detachment • Definitive proof is lacking…..

152 Borreliosis Borreliosis in other species • Organisms were found in the anterior chamber of a pony and 2 horses. • Humans exhibit conjunctivitis, keratitis, panuveitis, chorioretinitis, retinal detachment, optic neuritis and periorbital edema.

VO (2012) 15, 6, 398–405

153 Leptospirosis

• Motile spirochetal bacteriahttp://www.med.monash.edu.au/microbiology/staff/adler • The predominant serovars responsible for causing disease in dogs are canicola, icterohemorrhagica, grippotyphosa, pomona, and bratislava. • Maintained in host adapted species that act as reservoir hosts and is shed in the urine. • Direct transmission through contact with infected urine, bites, ingestion of affected material and contact with contaminated water.

154 Leptospirosis

• Vasculitis and endotheliitis involving the kidneys, liver, spleen, muscles, central nervous system, and eyes occur.

155 Leptospirosis Lesions in dogs Infrequent – conjunctivitis with mucopurulent oculonasal discharge – scleritis – anterior uveitis

Systemic signs – renal or hepatic failure or dysfunction.

156 Leptospirosis Disease in horses Acute signs – Transient depression, fever, icterus, anemia and anorexia. • Serologic surveys of horses have shown that exposure to Leptospira is common, but variable, according to the geographic location or climate. • Horses positive for leptospirosis are common in the Ohio, Delaware, Tennessee, and Mississippi river valleys.

157 Leptospirosis

• Leptospira interrogans most likely plays a role in many cases of ERU. • 20 serovars • L interrogans serovar pomona is most often associated with ERU. • Usually horses develop ERU 18 to 24 months after the initial infection.

158 159