UNIVERSITÀ DEGLI STUDI DI SASSARI SCUOLA DI DOTTORATO IN RIPRODUZIONE, PRODUZIONE, BENESSERE ANIMALE E SICUREZZA DEGLI ALIMENTI DI ORIGINE ANIMALE Direttore Prof. Giovanni Garippa INDIRIZZO IN: Produzione e Sicurezza degli Alimenti di Origine Animale (XXIV CICLO) (coordinatore: prof. Basilio Remo Floris) EPIDEMIOLOGY, VIRULENCE FACTORS AND ANTIBIOTIC RESISTANCE IN STAPHYLOCOCCUS AUREUS STRAINS ISOLATED IN SMALL RUMINANT DAIRY CHAIN Docente Guida Dott. Christian Scarano Direttore Tesi di dottorato del Prof. Giovanni Garippa Dott. Vincenzo Spanu ANNO ACCADEMICO 2010-2011 Vincenzo Spanu, “Epidemiology, virulence factors and antibiotic resistance in Staphylococcus 1 aureus strains isolated in small ruminants dairy chain”. Tesi di Dottorato in Produzione e Sicurezza degli Alimenti di Origine Animale, Università degli Studi di Sassari Table of contents Abbreviation …………………………………………………………………………………... 3 CHAPTER 1 ............................................................................................................................... 10 Introduction ................................................................................................................................ 10 1.1. Staphylococcus aureus epidemiology ............................................................................................. 11 1.2. Staphylococcus aureus in small ruminants dairy chain ................................................................... 13 1.3. Staphylococcus aureus virulence factors ......................................................................................... 16 1.3.1. S. aureus adherence factors (adhesines) ........................................................................... 17 1.3.2. S. aureus exoproteins ..................................................................................................... 19 1.4. Antibiotic resistance ........................................................................................................................ 22 1.5. Antimicrobial agents: ...................................................................................................................... 24 1.5.1. Beta-lactam antibiotics................................................................................................................. 24 1.5.2. Glycopeptides ............................................................................................................................... 26 1.5.3. Aminoglycosides ........................................................................................................................... 26 1.5.4. Quinolones ................................................................................................................................... 27 1.5.5. Macrolides .................................................................................................................................... 27 1.5.6. Nitromidazoles ............................................................................................................................. 28 1.5.7. Tetracyclines ................................................................................................................................ 28 1.5.8. Lincosamides ................................................................................................................................ 29 1.5.9. Nitrofurans ................................................................................................................................... 29 1.5.10. Sulfonamides .............................................................................................................................. 29 1.5.11. Chloramphenicol ........................................................................................................................ 30 1.6. Mechanisms of antibiotic resistance in bacteria population ............................................................ 31 1.7. Staphylococcus aureus and antibiotic resistance ............................................................................. 33 1.8. Molecular mechanisms of antibiotic resistance in S. aureus strains ................................................ 33 1.8.1. β-lactam resistance ...................................................................................................................... 33 1.8.2. glycopeptide resistance ................................................................................................................ 34 1.8.3. aminoglycoside resistance ............................................................................................................ 35 1.8.4. macrolide and lincosamide resistance ......................................................................................... 36 1.8.5. quinolone resistance ..................................................................................................................... 36 Vincenzo Spanu, “Epidemiology, virulence factors and antibiotic resistance in Staphylococcus 2 aureus strains isolated in small ruminants dairy chain”. Tesi di Dottorato in Produzione e Sicurezza degli Alimenti di Origine Animale, Università degli Studi di Sassari 1.8.6. tetracycline resistance .................................................................................................................. 37 1.9. References ....................................................................................................................................... 38 CHAPTER 2 ............................................................................................................................... 50 Thesis project ............................................................................................................................. 50 CHAPTER 3 ............................................................................................................................... 55 Antibiotic Resistance in Staphylococcus aureus and Coagulase Negative Staphylococci isolated from goats with subclinical mastitis. ......................................................................................................... 55 3.1. Introduction ..................................................................................................................................... 56 3.2. Material and methods ...................................................................................................................... 57 3.3. Results ............................................................................................................................................. 60 3.4. Discussion ....................................................................................................................................... 62 3.5. Conclusion....................................................................................................................................... 64 3.6. Tables .............................................................................................................................................. 65 3.7. References ....................................................................................................................................... 69 CHAPTER 4 ............................................................................................................................... 72 The pattern of enterotoxins and virulence factors genes in Staphylococcus aureus strains isolated from goat’s bulk tank milk....................................................................................................................... 72 4.1. Introduction ..................................................................................................................................... 73 4.2. Material and methods ...................................................................................................................... 74 4.3. Results ............................................................................................................................................. 77 4.4. Discussion ....................................................................................................................................... 79 4.5. Conclusion....................................................................................................................................... 81 4.6. Tables .............................................................................................................................................. 82 4.7. Figures ............................................................................................................................................. 82 4.8. References ....................................................................................................................................... 87 CHAPTER 5 ............................................................................................................................... 91 Antibiotic resistance in Staphylococcus aureus strains isolated from bulk tank goat’s milk in Sardinia. .. 91 5.1. Introduction ..................................................................................................................................... 92 5.2. Material and methods ...................................................................................................................... 92 5.3. Results ............................................................................................................................................. 95 Vincenzo