Exercise 1. Bovine mastitic milk sample A. Note relevant images are on next page Sample A is Staphylococcus aureus Moderate size (1.0 mm), circular, convex, cream-to-light yellow, opaque Double-zone (target) hemolysis Gram +ve cocci Clumps, pairs, Catalase +ve Coagulase +ve MAC No growth - - Ed No growth - -
Staph. aureus on Staph. aureus is coagulase positive
Exercise 1. Bovine mastitic milk sample B. Note relevant images are on next page Sample B is Streptococcus uberis Pinpoint to small (<0.5 mm), circular, translucent at 24 hours. Opaque, ~ 1mm at 48 hours Strains are (weak) alpha or nonhemolytic Recall - hemolysis shows zone of greening around colonies Gram +ve Chains of cocci Catalase -ve CAMP -ve MAC No growth - - Ed Growth - grey to brown colonies Due to hydrolysis of Esculin and formation of Fe precipitate - Esculin +ve
Streptococcus uberis at 48 hrs, Strep. uberis on Edwards agar note dark/silvery/grey colonies
Exercise 1. Bovine mastitic milk sample C. Note relevant images are on next page Sample C is Escherichia coli 2-3 mm greyish, single narrow zone of hemolysis Gram-negative rods, singly and in pairs Oxidase ve Indole +ve Citrate & Urease -ve MAC Growth, Lactose Fermentor (LF) intensely pink with pink in agar around colonies Ed No growth - -
E. coli showing hemolysis on Urease Citrate E. coli E. coli E. coli E. coli on MAC
Exercise 1. Bovine mastitic milk sample D. Note relevant images are on next page Sample D is Corynebacterium bovis Small, white, dry colonies nonhemolytic MAC No growth - Ed No growth Gram +ve Coryneform - rods & coccobacilli - L & V forms Palisades Catalase +ve Urease -ve
Note: we don t have a good picture of C. bovis - This is a high mag shot of C. pseudotuberculosis - C. bovis is more off-white, less glossy & no hemolysis Catalase test
Exercise 1. Bovine mastitic milk sample E. NOTE there are no images for CoNS Sample E is a Coagulase Negative Staphylococcus spp. (CoNS or CNS) Moderate size (1.0 mm), circular, convex, off-white, opaque Non- or single-zone hemolysis MAC No growth - Ed No growth - Gram +ve cocci Clumps, pairs, occasional short (3-4) chains Catalase +ve Coagulase -ve
Exercise 1. Bovine mastitic milk sample F. Note relevant images are on next page Sample F is Streptococcus dysgalactiae Small translucent colonies, Strains are typically alpha-hemolytic Recall - hemolysis shows zone of greening around colonies MAC No growth - Ed Growth hemolytic zone is often Visible Gram +ve cocci Short chains - Smears from milk sample tend to show chaining better - Catalase ve CAMP -ve Esculin -ve
Streptococcus dysgalactiae 48 hour plate Close-up of -hemolysis: zone of greening
Exercise 1. Bovine mastitic milk sample G. Note relevant images are on next page Sample G is Klebsiella pneumoniae Large (5-10 mm), light grey, coalescing, mucoid colonies Nonhemolytic MAC Large, mucoid, LF- pale pink - Ed No growth - Gram-negative Short, plump rods occurring singly or in pairs. A large, unstained halo may be evident particularly with Fuchsin counterstain this is the capsule Oxidase ve Indole ve Citrate & Urease +ve
Klebsiella pneumoniae on Urease Citrate Klebsiella pneumoniae on MAC K. pneumoniae K. pneumoniae K. pneumoniae