Bacterial Infections Flashcards
Diagnostic Methods for Bacterial Infections
Direct Microscopic Exam
• most cost effective
Isolation
• culture of bacteria on appropriate growth media
Direct detection of bacteria, bacterial antigens, nucleic acids, or toxins
• use immunohistochemistry, PCR, or others
• Important for microorganisms difficult to culture or limited serology
Serology
• use when presence of Ab in pop of clinically normal animals
• use to see increase in Ab titer
• may not confirm clinical dz
Interpreting Bacterial Results
Normal flora
• mixture of > 3 or 4 aerobic bacteria in low to moderate numbers from mucous membranes or external body surfaces probably represents normal flora.
Quantitation of growth
• large numbers of a single organism
• strong indicator of an infection
No growth
• sample did not have viable organisms present
• does not mean bacteria are not cause of problem.
What is Susceptibility Test & When is it indicated?
• in vitro assays used to predict in vivo susceptibility
• used if susceptibility is unpredictable, resistance anticipated, or dz life-threatening
Pyoderma in Dogs; responsible bacteria, how to diagnose
• Staph. pseudintermedius usually
• usually secondary to parasites, endocrinopathy, allergy
Diagnosis
• skin scrape
• cytology of pustules
• skin culture
• skin biopsy
Treatment for Pyoderma
• localized surface pyodermas can be treated topically
• generalized or deep need systemic antibiotics
• use Beta-lacatamase resistant antimicrobials
• Clavamox, oxacillin, cephalexin
Otitis Externa; responsible bacteria, cause, diagnosis
• usually Staph. pseudintermedius
• secondary to atopy, allergy, parasitism, abnormal conformation of ear, excessive moisture
Diagnosis
• otoscopic exam, cytology & culture of exudate
Otitis Externa; Treatment
• identify underlying cause
• clean ears
• topical therapy for uncomplicated cases
Otitis Media; responsible bacteria, cause, treatment, ototoxic drugs
• usually Staph. pseudintermedius
• usually extension of otitis externa
Treatment
• systemic antibiotics + topical for 4-6wks
do not apply Abs to external ear when ear drum perf is suspected
Ototoxic Drugs
• aminoglycosides, fluoroquinolones, erythromycin, polymyxin B, and chlorhexidine
Otitis Interna; responsible bacteria, cause, treatment
• Staph, Strep, Proteus, Pseudomonas, Enterococcus, E. coli
• extension of otitis externa/media or extension of pharyngeal organisms
Treatment
• systemic antibiotics + topical for 4-6wks
do not apply Abs to external ear when ear drum perf is suspected
Bite Abscess treatment
• most common cause of bacterial infection in cats
• MUST drain & give Abs
• penicillin V, ampicillin, amoxicillin
• topicals usually not effective
The most common organisms involved in localized myositis
• staph
• sometimes Clostridium perf
Joint Infections; responsible bacteria, cause, diagnosis, treatment
• from penetrating injury or hemtagoneous
• staph & strep most common in penetrating
Diagnosis
• septic arthritis often occupies only 1 joint
• non-infectious usually affects most joints
Treatment
• culture joint fluid
• 1st line of defese - cephalosporin or clavamox
Osteomyelitis; responsible bacteria, causes
• often Staph. pseudintermedius
• often secondary to tissue ischemia, sequestrum formation, foreign bodies, fractures, or surgical implants
Osteomyelitis; diagnosis & treatment
Diagnosis
• rads
• culture for aerobic & anaerobic bacteria
Tretament
• surgical debridement & drainage
• removal of insciting object
• antibiotics based on culture
• initiate cephalosporin or clavamox while waiting for culture
Diskospondylitis; responsible bacteria, causes, treatment
• most common is S. speudintermedius
• usually arises hematogenously from infection elsewhere
Treatment
• culture & sensitivity of blood or urine
• 1st gen cephalosporin until culture results
Bacteremia; responsible bacteria, causes, symptoms
• Usually stems from a localized infection
Bacteria
• S. speudointermedius (+) in dogs
• E. coli (-) in dogs
• Salmonella enteritidis in cats
Symptoms
• fever, trembling, tachycardia, hypotension, multi-organ dysfunction
Bacteremia; Diagnosis, Treatment
Diagnosis
• blood cultures
Treatment
• find primary infection ->
• target therapy at usual bacteria in that area
Drugs for Gram (+), Gram (-), & Anaerobes
Gram (+):
• first-generation cephalosporin; amoxicillin-clavulanate
Gram (-):
• aminoglycoside, fluoroquinolone
Anaerobe:
• ampicillin, metronidazole, clindamycin
Infective bacterial endocarditis; agent & diagnosis
• Often sequel to bacteremia
• most commonly caused by S. speudintermedius
• culture blood & cardiac ultrasound
Bacterial rhinitis causes & diagnosis
• often complication of nasal trauma, dental dz, foreign body, fungal infection, or neoplasia
• treat based upon culture & cytology
Tracheobronchitis; occurs in which species, agent
• AKA canine infectious respiratory dz complex
• often viral contributor
• most common bacteria is Bordetella bronchiseptica
Bacterial Pneumonia; Risk factors & agents
Risks
• esophageal disease,
• vomiting,
• recent anesthesia
• dz that compromise pulmonary defenses
• large group housing of puppies
Most common agents from upper airway
• B. bronchiseptica
• Pasturella
Most common agent from aspiration
• E. coli
Bacterial Pneumonia; diagnosis & treatment
Diagnosis
• 3 view rads
• trans/endotracheal wash
• bronchoalveolar lavage
• FNA of lung
• CBC often normal
• C & S recommended
Treatment
• up to 6wks
• treat to clinical resolution
• gram (+) & anaerobes - clavamox
• gram (-) - aminoglycosides
• mycoplasma - doxy
Pleural Infection; Agents & Pathophysiology
Agents
Dogs
• Nocardia, Actinomyces, E coli
Cats
• Bacteroides, Fusobacterium, Pasteurella
Path
• penetrating or migrating foreign body
• hematogenous or lymphatic spread
• extension from other abscesses
