Bacteria Bacteria of Ophthalmic Importance Diane Hendrix, DVM, DACVO Professor of Ophthalmology Bacteria Prokaryotic Organisms
Bacteria Bacteria of Ophthalmic Importance Diane Hendrix, DVM, DACVO Professor of Ophthalmology 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, but the DNA is organized into a single circular chromosome
www.norcalblogs.com/.../GeneralBacteria.jpg 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 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 Bacteria reproduction Asexual binary fission The bacterial growth cycle includes: the lag phase the logarithmic growth phase the stationery growth phase the decline phase Iron is essential for bacteria Bacteria Opportunistic bacteria Staphylococcus epidermidis Bacillus sp. Corynebacterium sp. Escherichia coli Klebsiella sp. Enterobacter sp. Serratia sp. Pseudomonas sp. (other than P aeruginosa). Infectivity Adhesins are protein determinates of adherence. Some are expressed in bacterial pili. Virulent factors increase the capacity of an organism to cause tissue inflammation and destruction. (Proteses, elastases, hemolysins, cytoxins) Secretomes and lipopolysaccharide core biosynthetic genes inhibit corneal epithelial cell migration Pseudomonas aeruginosa and Moraxella bovis
Bacteria
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. Bacteria
Conjunctival flora in dogs with ulcerative keratitis. Bacteria are more commonly isolated. Malassezia pachydermatitis is present in 23% of eyes with corneal ulceration 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. Bovine flora
Cladosporiumspp. and Penicillium spp.
No seasonal or housing difference.
May represent transient seeding from the environment, including the hay, as suspected in other species. Normal flora
Bats Alpacas Chelonians 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. Staphylococcus spp.
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). Staphylococcus spp.
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 Streptococcus spp. and related cocci
Ubiquitous, suppurative bacteria Enterococci are opportunists Streptococcal keratitis is relatively common
Most pathogenic Streptococci produce varying hemolysins. Streptococcus spp.
β-hemolytic Strep spp - 17% of dogs
S. equi subsp zoo - 12% and 22% of the isolates from horses. 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 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 Streptococcus spp.
Bastard strangles
Cases involving any area other than the pharyngeal area.
Ocular abnormalities
Serous then mucopurulent discharge
Panophthalmitis
Central blindness
Dx via culture or PCR Corynebacterium spp.
Gram + rods
Appear singly or in pairs
+/- clubbed ends
Flora of normal skin and mucous membranes 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 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 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 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 Swine listeriosis Septicemia Encephalitis Diagnosis clinical signs culture and identification of the organism from body fluids Pseudomonas spp.
Gram - rods Widely distributed. Found in the skin and mucous membranes. Cytologically indistinguishable from other rods Antibiotic susceptibility testing is especially important Pseudomonas aeruginosa Isolated from about 15% of horses with bacterial keratitis Isolated from 21% of dogs Innate resistance
Evans 2013 Pathogenic mechanisms
www.asylumresearch.co.uk/.../Bacteria/Cell!.jpg sciencephoto.com www.cdc.gov 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 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. IOVS 2011 March; 52(3): 1368–1377 Pseudomonas aeruginosa Resistance No resistance to gentamicin, tobramycin, ciprofloxacin, neomycin and polymixin B in horses at UT
At UF a statistically significant increase in resistance to gentamicin and tobramycin was found in horses between the isolates from 1992 to 1998 and those from 1999 to 2000.
Isolates of P. aeruginosa from dogs were susceptible to tobramycin and gentamicin and had limited resistance to ciprofloxacin (0.07%). Pseudomonas aeruginosa
Resistance 27 P aeruginosa isolates from dogs
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 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, 6 were sensitive only to imipenem, 3 to colistin, 2 to neomycin, 1 each to imipenem and colistin, imipenem and ceftazidime, and azithromycin. 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. Pseudomonas aeruginosa
Bacteriophages/ Predatory Prokaryotes
AJVR 2011 Aug;72(8):1079-86 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 Moraxella bovis
Transmission Opportunistic pathogen Environmental factors Exposure to UV light Irritants- face fly Host factors Genetic Nutritional Immune status Current infections 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. 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 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. 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 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 disease www.hgsc.bcm.tmc.edu/projects/microbial/Mbovis 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. Rogers DG, Cheville NF, Pugh GWJ. Pathogenesis of corneal lesions caused by Moraxella bovis in gnotobiotic calves. Vet Path 1987; 24(4):287-295. Moraxella bovis
Pink eye – Infectious Bovine Keratitis
Summer and fall
Younger cattle
Incubation period 2-3 days. 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 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 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) Moraxella bovis
Treatment - Subconjunctival
Procaine penicillin (1-2 ml) +/- subconjunctival dexamethasone (1-2 ml)
Oxytetracycline (100 mg/ml subconjunctival 1-2 ml) Moraxella bovis
Treatment - other
Ceftiofur crystalline-free acid (CCFA)(6.6 mg of ceftiofur equivalents/kg, SC)****
Tulathromycin 1 dose SC Tilmicosin SC (5 or 10 mg/kg) Moraxella bovis
Treatment
Nictitating membrane flaps or temporary tarsorrhaphies
Decreasing the fly population
Decreasing UV radiation
Autogenous vaccines
Cytokines with inactivated bacteria
Intranasal vaccines Moraxella bovoculi Isolated from IBK cases Blepharitis and conjunctivitis Respond to IBK treatments Association with M bovis? 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 Pasteurellosis Pasteurella multocida
Very small, non-motile, Gram - ovoid, coccoid or short rod http://www.med.monash.edu.au/microbiology/staff/adler/ Bipolar staining
Aerobic and facultatively anaerobic Pasteurellosis Opportunistic bacteria
Virulent factors endotoxin adhesins filamentous appendages help P. multocida colonize mucous membranes Pasteurellosis
Clinical signs in rabbits Rhinitis (or snuffles) Pneumonia Genital infections Wound infections Abscesses www.mri.sari.ac.uk/%5Cjpg%5Cbact Otitis media - rep10 - fig2b.jpg fig2b.jpg 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 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. Brucellosis
Ocular signs Occur in ~ 14 % of dogs with brucellosis.
Endophthalmitis
Chronic uveitis
Hyphema
Chorioretinitis 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 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 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. Haemophilus spp. Haemophilus 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. Thromboembolic Meningoencephalitis Haemophilus somnus Acute septic TEME most commonly occurs in feedlot cattle
Can Vet J. 1971 September; 12(9): 180–182. Bovine tuberculosis Zoonotic Disease Acid-fast bacterium, Mycobacterium bovis Ocular tuberculosis is rare in cattle and swine
subretinal exudation Basic Science Guides Design of New TB Vaccine Candidates M. J. Friedrich JAMA. 2005;293:2703-2705. http://jama.ama-assn.org/cgi/content/extract/293/22/2703 retinal hemorrhage Affected small animals anterior uveitis are in farm settings and endophthalmitis with a are drinking granulomatous response unpasteurized milk. 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 Mycoplasma
Lack a true cell wall, but have a plasma membrane. accounts for their plasticity and pleomorphism, including cocci, spiral filament, and ring-like structures
http://www.malp-research.de/malp_history.html, webmedia.unmc.edu/.../2SL31-mycoplasma.jpg 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 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 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 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 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 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 Mycoplasma
Mycoplasma bovis Cattle
Pneumonia
Arthritis
Mastitis
Infertility
Subcutaneous abscesses in cattle
Keratoconjunctivitis 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 The cell replication cycle involves:
Extracellular (elementary body)
0.2-0.6 µm in size with rigid cell walls Chlamydophila psittaci
Intracellular (initial body, reticulate body) bodies of Elementary
0.5 – 1.5 µm
lack cell walls stain). eosin and hematoxylin liver, (Parrot, hepatocytes of cytoplasm the in ) Chlamydia psittaci http://upload.wikimedia.org/wikipedia/en/thumb/1/1a/Chlamydophila_pneumoniae.jpg/200px - Chlamydophila_pneumoniae.jpg www.vet.uga.edu/.../turnerandrobbins/Fig1.jpgFigure 1. (previously 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 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. 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. Chlamydophila felis
Clinical signs
initial chemosis
suppurative conjunctivitis
petechial hemorrhages
conjunctival lymphoid follicles
+/- respiratory signs 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. 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 Chlamydophila felis
Treatment Topical oxytetracycline QID for 2 weeks past resolution of clinical signs
Erythromycin and chloramphenicol are also effective
Pradofloxacin vs doxycycline Disease in Farm Animals Chlamydophila pecorum
Chlamydophila abortus
Chlamydia suis C. pecorum Cattle, sheep and swine Encephalomyelitis Enteritis Polyarthritis Metritis Pneumonia Conjunctivitis Typically young animals are affected in sporadic outbreaks. C. abortus
C. abortus Sheep Conjunctivitis Keratitis Polyarthritis Pneumonia Orchitis Epididymitis Abortion Chlamyodophilosis among lambs and kids may produce both ocular signs and polyarthritis. 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 C. abortus
Treatment
Topical oxytetracycline is used to treat lambs and kids
LA200 is effective
Usually self limiting in 2-3 weeks. 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. 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 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. Chlamydophila psittaci
Serotypes All share an identical genus-specific antigen in their lipopolysaccharide Currently, 8 serotypes are recognized The same strain may cause mild disease or asymptomatic infection in one species, but severe or fatal disease in another species. Avian serotypes are capable of infecting people and other mammals. 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 period typically is 3-10 days. 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 Chlamydophila psittaci www.vet.uga.edu/vpp/clerk/Bockino/Fig1.jpg Diagnostics 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 Chlamydophila pecorum
Disease in koalas keratoconjunctivitis urinary tract disease reproductive tract disease rhinitis/pneumonia
Veterinary Microbiology 165 (2013) 214–223 Chlamydophila pecorum
Treatment
Response to treatment is variable Decreased palpebral fissure, entropion and corneal scarring may result. Enrofloxacin, chloramphenicol Not tetracyclines and macrolides 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. 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 Bartonella
In Dogs B henselae, B vinsonii, B clarridgeiae, & B elizbethae Anterior uveitis Hyphema Chorioretinitis Retinal detachment due to systemic hypertension Multiple systemic signs Diagnosis is based on serology 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. Neonatal septicemia/bacteremia
Commonly isolated bacteria in foals E coli Klebsiella spp Actinobacillus spp Enterobacter spp Pseudomonas spp Rhodococcus equi 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 Neonatal septicemia/bacteremia
Frequently affected organ systems Umbilical remnants CNS Respiratory Cardiovascular Musculoskeletal Renal Hepatobiliary GI organs Foals in the early stages of sepsis are depressed and lethargic. The foals do not nurse with normal frequency. Neonatal septicemia/bacteremia
Ophthalmic findings Fibrin in the anterior chamber Hypopyon Severe miosis Entropion (if the foal is dehydrated) Neonatal septicemia/bacteremia Commonly isolated bacteria in farm animals E coli Klebsiella spp Actinobacillus spp Streptococcus spp Arcanobacterium pyogenes Salmonella spp Pasteurella spp 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 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. Anaerobic Pathogens
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. 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. 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. Anaerobic Pathogens
Stromal abscess in a dog.
Implicated in necrotic and suppurative deep tissue infections
Often mixed infections with facultatively anaerobic bacteria Other Bacterial Infections
Rickettsia Ehrlichia Borrelia Leptospira 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%... Rocky Mountain Spotted Fever R rickettsii An acute febrile illness in dogs and humans. USA, Western Canada and Central and South America. 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... 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. 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. Rocky Mountain Spotted Fever Ocular signs Altered vascular permeability in the conjunctiva, uvea, and retina results in ocular signs. Rocky Mountain Spotted Fever
Conjunctivitis conjunctivitis chemosis petechial hemorrhages mucopurulent to purulent ocular discharge Anterior segment iris stromal petechiations anterior uveitis hyphema 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 Rocky Mountain Spotted Fever 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 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. Rocky Mountain Spotted Fever Diagnosis
rising serum titers on micro IFA test isolation www.cdc.gov/ncidod/dvrd/rmsf/IMAGES/rick • www.answers.com/.../rocky - - mountain spotted - IFA.jpg - fever 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. Ehrlichia canis
Causes canine monocytic ehrlichiosis
Acute, subclinical and chronic disease.
Gram - bacteria
Lack peptidoglycan and lipopolysaccharide components. 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. 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. 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. E. canis
Subclinical phase The subclinical phase lasts for weeks to months.
Clinical signs may regress. 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 E. canis
Ocular signs Associated with:
acute vasculitis
perivasculitis
thrombocytopenia
platelet dysfunction
hyperviscosity E. canis
Ocular signs Conjunctival hyperemia and hemorrhages Corneal edema Deep corneal vascularization Anterior uveitis Chorioretinitis Panuveitis Optic neuritis E. canis
Chronic ocular signs
hyperproteinemia and hyperviscosity syndrome lead to retinal vascular engorgement E. canis
Diagnosis Laboratory abnormalities Presence of morula on stained blood smears Bone marrow cytology with hypoplastic elements, plasmacytosis, and mastocytosis IFA and PCR 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. Anaplasma platys Rickettsial parasite
Causes infectious thrombocytopenia in dogs
Reported to cause uveitis
E. chaffeensis, E. ewingii, and E. equi (in dogs) may also cause anterior uveitis. Borreliosis or Lyme’s Disease
Tick-borne spirochetosis Borrelia burgdorferi Small corkscrew shaped motile microaerophilic bacteria. Do not survive free living in the environment.
www.medicalecology.org/diseases/lyme/em.jpg Highest incidence of disease remains in the northeastern US. 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 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. 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….. 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 Borreliosis
Diagnosis
There is a high prevalence of serum + antibody titers (75%) with actual disease in ~ 5-10% of dogs.
Current lab tests employ the specific c6 lipoprotein antigen in ELISA and western blot
www.lersus.de/.../1/res/files/borrelia_0_.jpg Leptospirosis
http://www.med.monash.edu.au/microbiology/staff/adler Motile spirochetal bacteria 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. Leptospirosis
Vasculitis and endotheliitis involving the kidneys, liver, spleen, muscles, central nervous system, and eyes occur. Leptospirosis
Lesions in dogs
Infrequent conjunctivitis with mucopurulent oculonasal discharge scleritis anterior uveitis
Systemic signs renal or hepatic failure or dysfunction. 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. 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. Diagnosis
Sequestered in kidneys, liver, www.buddycom.com/bacteria/nongram/leptofa1346.jpg spleen, CNS and eyes. Clinical signs Microscopic agglutination test or ELISA Histology PCR Cultured from the aqueous humor of dogs Can be shed in the urine up to 3 months
Proteases and toxins Increase virulence by damaging tissue and interfering with host defense systems. Exo-products contribute directly to keratitis through toxic effects on corneal cells and degradation of corneal proteins and indirectly through activation of corneal proteases.