Concise Review of Veterinary Microbiology

P. J. Quinn, B. K. Markey, F. C. Leonard, E. S. Fitzpatrick, S. Fanning

• Publisher: Wiley-Blackwell
• Year: 2015
• Print ISBN: 9781118802700
• eBook ISBN: 9781118802694
• Edition: 2
• Topic: Medicine
• Subtopic: Veterinary Medicine

Updated to reflect the latest developments in the field, Concise Review of Veterinary Microbiology, 2nd Edition, presents essential information on veterinary microbiology for students and those requiring a refresher on key topics relating to microbial diseases in animals. Morphological, cultural and other descriptive features of pathogenic microorganisms are described, together with their habitats and aetiological roles in disease production in animals and, where appropriate, in the human population.

Key features:
• There are five sections covering bacteriology, mycology, virology, biosecurity and other aspects of infectious diseases
• Provides concise, yet comprehensive information on pathogenic microorganisms of importance in veterinary medicine, the diseases which they cause, their diagnosis and control
• The 79 short chapters in this book include 13 new chapters on antibacterial resistance, structure and function of the immune system, antifungal chemotherapy, antiviral chemotherapy, principles of biosecurity and a number of topics related to the control and prevention of infectious diseases
• This latest edition uses updated nomenclature and includes detailed diagrams now in full colour, and comprehensive tables

Section II
Pathogenic Bacteria

14 Staphylococcus species

Staphylococci are Gram-positive cocci, approximately 1 μm in diameter, which form irregular clusters resembling bunches of grapes. They occur as commensals on skin and mucous membranes; some act as opportunistic pathogens causing pyogenic infections. They are comparatively stable in the environment. The coagulase-positive S. aureus subsp. aureus (referred to as S. aureus) and S. pseudintermedius and the coagulase-variable S. hyicus are important pathogens of domestic animals. Coagulase, which converts fibrinogen in plasma to fibrin, is a virulence factor of these organisms which correlates with pathogenicity. Coagulase-negative staphylococci are usually of low virulence. In clinical specimens, Staphylococcus species must be differentiated from Streptococcus species and from Micrococcus species. Staphylococci are generally catalase-positive and streptococci catalase-negative. Staphylococcus species are usually identified by the appearance of their colonies, haemolytic pattern and biochemical profiles. Molecular typing methods are increasingly being used to assign S. aureus and S. pseudintermedius to clonal complexes. Such methods include multi-locus sequence typing, analysis of patterns following enzymatic digestion and pulsed-field gel electophoresis and staphylococcal protein A typing.

Because staphylococci are pyogenic bacteria, they often cause suppurative lesions. Minor trauma or immunosuppression may predispose to the development of infection. Virulence factors of S. aureus and their pathogenic effects are indicated in Table 14.1. Although some virulence factors are plasmid-mediated, many are encoded in the staphylococcal core genome. Staphylococcal diseases of importance in domestic animals include mastitis, tick pyaemia, exudative epidermitis, botryomycosis and pyoderma (Table 14.2).

Table 14.1 Virulence factors, including toxins, of Staphylococcus aureus and their pathogenic effects.

Virulence factor	Pathogenic effects
Coagulase	Conversion of fibrinogen to fibrin. Fibrin deposition may shield staphylococci from phagocytic cells
Lipase, esterases, elastase, staphylokinase, deoxyribonuclease, hyaluronidase, phospholipase	These factors facilitate dissemination and enhance toxicity of the organisms
Protein A	Surface component which binds the Fc portion of IgG and inhibits opsonization
Leukocidin	Cytolytic destruction of phagocytes of some animal species
Alpha-toxin (α-haemolysin)	The major toxin in gangrenous mastitis. It causes spasm of smooth muscle and is necrotizing and potentially lethal
Beta-toxin (β-haemolysin)	A sphingomyelinase which damages cell membranes
Toxic shock syndrome toxin (TSST)-1	Superantigen activity
Exfoliative toxins	Responsible for desquamation in staphylococcal ‘scalded skin syndrome’ in humans
Enterotoxins	Heat-stable toxins associated with staphylococcal food poisoning in humans

Table 14.2 Coagulase-positive staphylococci and their clinical importance.

Species	Hosts	Clinical conditions
Staphylococcus aureus	Cattle Sheep	Mastitis, udder impetigo Mastitis Tick pyaemia (lambs) Benign folliculitis (lambs) Dermatitis
	Goats	Mastitis Dermatitis
	Pigs	Botryomycosis of mammary glands Impetigo on mammary glands
	Horses	Scirrhous cord (botryomycosis of the spermatic cord), mastitis
	Dogs, cats	Suppurative conditions similar to those caused by S. pseudintermedius
	Poultry	Arthritis and septicaemia in turkeys Bumblefoot Omphalitis in chicks
S. pseudintermedius	Dogs	Pyoderma, endometritis, cystitis, otitis externa, and other suppurative conditions
	Cats	Various...

Table of contents

• Cover
• Titlepage
• Copyright
• Preface
• Acknowledgements
• Abbreviations and definitions
• About the companion website
• Section I: Introductory Bacteriology
• Section II: Pathogenic Bacteria
• Section III: Mycology
• Section IV: Viruses and Prions
• Section V: Prevention and Control of Infectious Disease
• Appendix: relevant websites
• Index
• EULA