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
