DEEP BACTERIAL INFECTIONS OF DOGS AND CATS: DEEP BACTERIAL INFECTIONS OF DOGS AND CATS VMED 5372 Infectious Diseases Dr. Foil


OVERVIEW: OVERVIEW Actinomycosis Nocardiosis Mycobacterial Diseases Tuberculosis Leprosy Atypical Mycobacterial Infection


What Do I Need to Know?: What Do I Need to Know? Really basic microbiology How Acquired? Common Presenting Signs Basic Diagnostic Parameters Basic Treatment Parameters DDX for Mycetoma


Actinomycosis: Actinomycosis Actinomyces spp -- branching, filamentous anaerobic or microaerophilic inhabitants (commensals) of oral cavities of animals and man


Actinomycosis: Actinomycosis Infections are associated with puncture wounds inc. bite wounds Many cases are associated with migrating plant foreign bodies


Actinomycosis: Actinomycosis Adult large breed (sporting breed) dogs are most commonly affected


Clinical Features: Clinical Features Localized pyogranulomas, abscesses or body cavity effusion are seen Most abscesses or draining tracts are found on the head or neck


SULFUR GRAINS: SULFUR GRAINS Exudate is like tomato soup with sulfur grains! Sulfur grains are soft mucoid clumps of organisms


CAUSES OF MYCETOMA: CAUSES OF MYCETOMA Actinomycotic Mycetoma Botryomycosis Eumycotic Mycetoma Pseudomycetoma Actinomyces, Nocardia or other actinomycete Other bacterial infections e.g. Staph Saprophytic fungi Microsporum canis in Persian cats


PYOTHORAX: PYOTHORAX Often associated with plant foreign body Clinical signs = exercise intolerance, weight loss, fever, tachypnea, dyspnea Occasionally, tracts will form through the chest wall


Osteomyelitis: Osteomyelitis Often vertebrae or long bones Often associated with bite wounds


Skin Infections: Skin Infections


Cytologic Diagnosis: Cytologic Diagnosis Careful examination of exudate for sulfur granules These can be crushed and smeared on glass slides Gm positive filamentous branching rods ALL ACTINOMYCETES have similar morphology


ANAEROBIC CULTURE: ANAEROBIC CULTURE A large quantity of exudate WITH sulfur grains is needed to the microbiology lab, fast, in capped syringe Anaerobic transport media even better A large sample of affected tissue may be an alternative


3 PRINCIPLES OF THERAPY: 3 PRINCIPLES OF THERAPY L Lavage and drainage of affected areas. L Debridement of granulation tissue and granulomatous masses. L Long-term antibiotic therapy (weeks to months)


ANTIBIOTICS FOR ACTINO: ANTIBIOTICS FOR ACTINO Penicillin is the drug of choice Pen G 100,000 units/kg q 12-24 h IM, SQ Pen V 50 mg/kg q 8 h PO). Alternatives: erythromycin, minocycline, clindamycin, or chloramphenicol Sensitivity testing is recommended


Nocardiosis: Nocardiosis Nocardia spp are aerobic saprophytic organisms found in rich soil N. asteroides complex N. nova is most commonly associated with disease in dogs and cats N. brasiliensis and N. caviae are sometimes isolated Nocardia infections are much less common (1:9) than Actinomyces in dogs


Nocardiosis: Nocardiosis Infection associated with wound contamination with soil or by inhalation. Inhalation infection or dissemination from a localized infection occurs in immunocompromised hosts


Nocardia --3 major forms: Nocardia --3 major forms Localized: Non-healing wounds with local extension possible, regional lymph node abscessation. Sulfur granules may or may not be present Pyothorax: Signs similar to Actinomycosis but more acutely ill. Sulfur granules may or may not be present. Disseminated form: resembles canine distemper


Cytologic Diagnosis: Cytologic Diagnosis Beaded, filamentous Gram-positive rods Acid-fast stain MAY be positive


AEROBIC CULTURE: AEROBIC CULTURE May require up to 2 weeks SLOW Acid-fast stains on colonies in culture may be more successful than those on tissue or exudate


THERAPY: THERAPY Except in disseminated disease, the 3 therapeutic principles given for Actinomycosis apply First choice antibiotics: Triple sulfa, sulfadiazine or sulfamethoxazole Amikacin, enrofloxacin or minocycline are other choices


Streptomyces – another Actinomycete: Streptomyces – another Actinomycete


MYCOBACTERIA: MYCOBACTERIA Mycobacteria are aerobic, non-spore forming, non-motile, gram-positive, acid-fast, large, slender, beaded rods


MYCOBACTERIA: MYCOBACTERIA Tuberculous Group Leprosy Group Saprophytic (Atypical) Groups I-IV M. tuberculosis M. bovis M. avium M. leprae M. lepraemurium M. avium-intercellulare M. fortuitum group M. chelonae group M. smegmatis group


Tuberculosis in Dogs and Cats: Tuberculosis in Dogs and Cats Incidence increasing because of AIDS Increasing incidence of multiple-drug resistant TB Exposure to infectious body fluids is means of transmission This is a reverse zoonosis – most important in dogs


TB -- Forms of Disease: TB -- Forms of Disease Bronchopulmonary Gastrointestinal Disseminated In all 3 forms, dogs and cats often develop oropharyngeal lesions


BRONCHPULMONARY TB: BRONCHPULMONARY TB ADL, fever, weight loss, and cough Oropharyngeal -- dysphagia, retching, ptyalism, tonsillar enlargement Chest radiographs -- tracheobronchial lymphadenopathy, interstitial to finely granular to consolidating parenchymal infiltrate, calcified nodular densities or pleural or pericardial effusion


GASTROINTESTINAL TB: GASTROINTESTINAL TB Oropharyngeal Symptoms Weight Loss, Anemia, Vomiting Malabsorption Type of Diarrhea Mesenteric Lymph Node Enlargement and Thickened Bowel Loops Palpable


DIAGNOSIS: DIAGNOSIS Can be very challenging Cytologic Examination –Lg Gm + Rods; Acid-Fast Tissue for Path & Culture Large Amounts of Exudate or BX for Culture TB Take Several Weeks; Require Special Agars Intradermal Skin Testing May Be Useful for Dogs but Not Cats


TREAT TB?: TREAT TB? Treatment of Dogs and Cats Is Usually Not Recommended Only With Permission From Public Health Authorities Agents in Combination As in Humans Isoniazid With Rifampin, Streptomycin or Ethambutol (2 Drugs)


Atypical Mycobacterial Infections: Atypical Mycobacterial Infections Atypical Mycobacterial Pyogranulomatous Panniculitis Pulmonary Disease Disseminated Disease


ATYPICALS – WHERE?: ATYPICALS – WHERE? Saprophytic Mycobacteria are ubiquitous in moist sites in the environment. They have been isolated from soil, water, drain pipes, and even bandage materials in hospitals. They are common laboratory contaminants


DDX PANNICULITIS: DDX PANNICULITIS Infectious causes: nocardiosis, actinomycosis, pythiosis, sporotrichosis, botryomycosis, eumycotic mycetoma, blastomycosis, cryptococcosis, tuberculosis, chronic abscessation secondary to FeLV or FIV infection, Rhodococcus equi abscess, bacterial L-forms Non-infectious causes: lymphoreticular or mammary neoplasia, foreign body, nutritional pansteatitis and sterile nodular panniculitis


How Is It Acquired?: How Is It Acquired? MB enter through contaminated wounds Entry in SQ fat is especially important Patients are not immunosuppressed


What Does It Look Like?: What Does It Look Like? Nodular to ulcerative, fibrosing Greasy hemorrhagic purulent exudate Opening of new drainage sites *Surgical excision is typically followed by rapid recrudescence at the surgery site*


DIAGNOSIS: DIAGNOSIS Culture of biopsy-obtained tissues is most reliable The Type IV organisms grow rapidly on either standard or enriched agars Specific ID should always be requested; +/- C & S testing


DIAGNOSIS: DIAGNOSIS Can be Dx’d presumptively on Histopath Takes experience and a Vet Pathologist Special processing for Acid-Fast Stains


TREATMENT: TREATMENT Long-term therapy Relapse on or after tx a problem Surgical debridement Drugs most often effective for fortuitum group -- amikacin, cefoxitin, sulfonamides, fluoroquinolones; +/- clarithromycin and doxycycline, clofazimine. Antituberculosis drugs are not effective