22/09/2010. Laboratory 2a + b Staphylococci and Streptococci

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1 Laboratory 2a + b Staphylococci and Streptococci 1

2 Hamster: To be or not to be..!? (a play on Ham-let!) Summary on Exercise 1 (Lab 2a) Big colony heavy growth, color? Double-zone hly CAT and Tube Coag +ve Gram-pos. cocci Little colony 1-5%, color? Non-hly/ synergistic hly CAT +ve, Coag ve Gram-pos. cocci Tentative i.d. with this info (+ what you know) S. aureus S. intermedius group S. schleiferi subsp. coagulans S. hyicus Why Penicillin bad for hamsters? Antibiotic Associated Enterotoxemia Dysbiois Clostridium spp. + potentiated sulfa-drug, Enrofloxacin etc. What unchecked pyoderma results in! Lab 2b Exercise 1 Most likely i.d. s, based on scenario, colony, microscopy, Catalase, Coagulase etc. A. Setter pyoderma Staph. pseudintermedius B. Greasy Pig Staph. hyicus C. Equine metritis - Strep. equi subsp. zooepidemicus D. Holstein mastitis Strep. dysgalactiae subsp. dysgalactiae E. Cat UTI Enterococcus faecalis - a tough one that you should have had on your r/o list but challenging to nail -down with the tests you had available 2

3 Lab 2b: Exercise 2 and Questions 2. arthritic pig (see exercise 2 from lab 2a) Small, circular, +/- wet, alpha-hemolysis (can be weak at 24 hours) Gram-positive cocci, Catalase negative Note: you can get an odd lancet-morphology with this species of Strep. under the microscope Google Image Streptococcus-lancet shape and you will see that S. pneumoniae does the same thing I.d. = Streptococcus suis Questions: 1. Disease conditions are staph commonly associated with in Dogs SSTI s (Skin + Soft Tissue Infections), otitis externa, UTI, reproductive etc Cows Mastitis, Pigs - young pigs (dermatitis, septicemia, arthritis); mastitis Insows and questions 2. Major disease from Streps we ve seen today Bovine Streps mastitis: S. agalactiae, dysgalactiae and uberis Equine Streps S. equi strangles (cervical lymph nodes ) / bastard strangles (mediastinal/mesenteric lymph node involvement), pneumonia S. zooepidemicus - reproductive, respiratory pathogen important Porcine Strep(s) S. suis - ~ 35 strains very, very impt economically, vaccine efficacy, abx-resistance are problems. Multiple clinical presentations: bacteremia, pneumonia, meningitis, arthritis, endocarditis 3

4 MRSA/MRSI/MRSP/MRSS!? Methicillin Resistant Staph. Aureus in case you forgot! Out there yup! MRSA People-to- dogs MRSP p for pseudintermedius Dogs-to-people MRSS -? s: for schleiferi subsp Asymptomatic, transient Immunocomp. at risk SSTI skin. soft tissue infection Septic Infections Pneumonia Report How we i.d. methicillin resistance Sensitive Staph. aureus Oxacillin Cefoxitin 30 Resistant or Sensitive Now What? Resistant PBP 2a Confirmation Ag detection meca PCR MRSA Report - beta-lactam resistant Methicillin is related to Penicillin but penicillinase resistant. Oxacillin is more reliable for susceptibility testing in-vitro. Intervention once you know Barrier Nursing Precautions: Hospitalized Prevention: HANDWASHING Chlorhexidine-based best Cover your lesions, avoid exudates and excretions Love your dog - without all the licking, or bed-sharing!! Pet dishes (daily), beds (weekly), quarantine gramps!! Decolonization Yikes! vs transient colonization and waiting? People: Showers chlorhexidine ( Hibiclens ) antiseptic soap and mupirocin nasal cream Dogs/cats/horses is it practical? chlorhexidine or benzoyl peroxide (Etiderm) baths, mupirocin (offlabel Canada + resistant strains?) vancomycin creams 4

5 Abx Intervention? Systemic Antibiotic Therapy (MRSA but not ALL-RSA ) SSTI s, septicemia, septic arthritis, pneumonia infections or highly virulent strains MIC s invaluable Candidate Abx Debate as to beta-lactams or not in humans Clindamycin, Tetracyclines, potentiated sulfonamides (Morris says Clindamycin not good, uses potentiated sulfa-drugs Chloramphenicol or Amikacin as last resort atology/2010-ce_s1-4-4_staphylococci.pdf - Morris,