Basic Swine Bacteriology

Enteric Pathogens
Escherichia coli
Blood agar Most pathogenic strains will be β haemolytic or smooth and mucoid	MacConkey’s Pink colonies – lactose fermenter	Tergitol Yellow- gold colonies lactose fermenter
A B C	Tests – A – Urease –ve yellow B – Simm’s + ve red colour C – Kligler’s +ve with gas Oxidase -ve	Gram negative rod
Clostridium perfringens
	Requires anaerobic culture. Note flat spreading colony shape. Double zone of haemolysis.		Gram positive rods – vegetative and solid rods some spore formation
Blood agar
Brachyspira hyodysenteriae and Brachyspira pilosicoli
	Requires anaerobic culture and 42C. A filmy surface growth is typical, rather than distinct individual surface colonies. β haemolytic Bacteria lie under the surface.			Weakly Gram positive spirochaetes.

Salmonella spp. There are over 2300 types of salmonella
Blood agar Salmonella strains are non-haemolytic on blood agar	MacConkey’s A non-lactose fermenter		Tergitol – a non-lactose fermenter
A B	Tests – A – Kligler’s Iron agar –H2S + Lactose Blue colour B - Lysine Iron Agar + ve Blue colour	Gram negative rod
Lawsonia intracellularis
Note L. intracellularis requires cell culture. It will not grow on agar media

Respiratory pathogens
Actinobacillus pleuropneumoniae
Blood agar Requires staphylococcus streak - Haemolytic - satellitism		MacConkey’s – No growth					Tergitol - No growth
APP left, HPS right plates		Differentiation between APP and HPS by cultural characteristics and urease positive – blue coloration and is CAMP positive.					Haemolytic colonies
			Gram negative rods and coccobacillary forms Organism generally requires NAD (Nicotinamide adenine dinucleotide to grow – V factor) – supplied by a Staphylococcus streak.
Bordetella bronchiseptica
Blood agar - Incubate for at least 48 hours		MacConkey’s - non lactose fermenter					Tergitol – non lactose fermenter
A B C D			A – Kligler’s –ve red B – Simm’s – Poor reaction little growth C- urease – Strong positive – pink slant D - Simmon’s citrate agar – positive – blue color Oxidase +ve		Small gram negative coccobacilli
Pasteurella multocida
Blood agar assisted with Staphylococcus streak to distinguish A and D by producing mucoid colonies				MacConkey’s – no growth Tergitol – no growth
P. multocida A mucoid colony - may run together	P. multocida D non mucoid – dry colony
A B C			Tests – note distinctive odor – musky A – Dextrose Broth - +ve red no gas. B – Lactose –ve yellow C - Indole positive red In addition - urease negative			Small Gram negative rod or coccobacillus
Salmonella choleraesuis See enteric pathogens for growth characteristics
Streptococcus suis
Blood agar		MacConkey’s – no growth					Tergitol – no growth
		Note type of haemolysis α haemolysis - green, β haemolysis – clearing Catalase –ve					Gram positive small cocci –in chains or pairs

Actinobacillus suis
Blood agar – wide zone of β haemolysis	MacConkey’s – no growth Sometimes very small				Tergitol – no growth
A B C	Tests – No growth on MacConkey’s or Tergitol important differential from E. coli A - Kligler’s – Lactose +ve Dextrose +ve red B – Simm’s – difficult little reaction C – Urease +ve red				Gram negative rod
Haemophilus parasuis
Blood agar – very small colonies around the Staphylococcus streak			MacConkey’s – no growth			Tergitol – no growth
		Can be difficult to grow – requires NAD. Reputedly Grows best under CO2 on chocolate agar. It is urease negative - yellow – useful to distinguish from APP positive - blue.		Gram negative coccobacillus

Arcanobacterium pyogenes
Blood agar Catalase -ve	MacConkey’s – no growth	Tergitol – no growth
	Gram positive pleomorphic rods – “Chinese letters”
Mycoplasma hyopneumoniae
Mycoplasma’s require special media. M. hyopneumoniae requires a very long incubation period and a specialized laboratory to grow the organism, which even then is frequently overgrown with other mycoplasma spp.

Other pathogens
Erysipelothrix rhusiopathiae
Blood agar – small colonies	MacConkey’s – no growth			Tergitol – no growth
		Tests - Produces hydrogen sulfide (black streak) along stab line in Kligler’s iron agar.	Slender Gram positive rod
Actinobaculum suis (Eubacterium suis)
Gram positive pleomorphic rods
				Tests – urease positive
Blood agar – requires anaerobic culture. Flat colonies fried egg shaped	Pleomorphic rods
Staphylococcus spp. – Example - Staphylococcus hyicus
Blood agar	MacConkey’s No growth			Tergitol No growth
	Gram positive cocci – in clumps resembling grapes Catalase positive