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Understanding Gram-Positive Bacteria: Classifications and Pathogenicity Factors

Explore classifications of Gram-positive bacteria, including Actinobacteria and Bacilli, and delve into the pathogenicity factors of Staphylococcus, Streptococcus, Enterococcus, Bacillus, Clostridium, Listeria, and Erysipelothrix. Analyze antibiotic resistance, virulence factors, and diseases caused by these bacteria in humans and animals.

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Understanding Gram-Positive Bacteria: Classifications and Pathogenicity Factors

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  1. Classification of Gr+ bacteria (I part) • Tribe: Actinobacteria • Class: Actinobacteria • Order: Actinomycetales • F.: Micrococcace • F: Corynebacteriaeceae • F: Mycobacteriaceae • F: Nocardiaeace

  2. Classification of Gr+ bacteria (II part) • Class : Bacilli • Order : Bacillales • F.: Bacillaceae • F.: Listeriaceae • F.: Staphylococcaceae • Order: Lactobacillales • F.: Lactobacillaceae • F.: Enterococcaceae • F.: Streptococcaceae

  3. Class: Actinobacteria • Order : Actinomycetales • F: Micrococcaceae

  4. G+ cocci • F: Micrococcaceae (catalase +) • Genera: • Micrococccus (M.luteus) • Kocuria (K.rosea) • Dermacoccus

  5. Class: Bacilli • Order Bacillales • F. Staphylococcace • Order Lactobacillales • F: Streptococcaceae • F.:Enterococcaceae • F.:Lactobacillaceae

  6. Staphylococcus • Coagulase positive staphylococci (CPS) • Toxins: • hemolysines (alpha, beta, gama, delta) • enterotoxines • exfoliative toxin • Coagulase negative staphylococci (CNS)

  7. Staphylococcal species • CPS • S.aureus • S.intermedius, S.pseudointermedius • S.hyicus subsp. hyicus • CNS • S.epidermidis • S.chromoges S.sciuri

  8. Resistant isolates 90% - penicillins 4O%- macrolides/. linkosamides MRSA- methicillin rezistant S.aureus Aditional penicilline binding proteins PBP are produced ´ with low avidity to betalactams Antibiotic rezistence in S.aureus

  9. Antibiotic rezistence in S.pseudointermedius • MRSP isolates from dogs in Sweden • mecA gene • Isolates from post operative wound infections

  10. Antibiotic rezistence in S.intermedius • Multiresistant strains. Clindamycin erytromycine,streptomycine, tetracycline and enrofloxacin

  11. Streptococcus Pyogennic haemolytic streptococcoci S.pyogenes (ser. group A) human infections • S.agalactiae (ser. group B) cattle, man , pig • S.equi (group C) • S. equi subsp. • S.canis (group G) • Other non-haemolytic streptococci: S.suis

  12. New species S.suis • S.suis decribed (1987) and validated (1992) • Major host: pig • Pathogenicity for pigs and humans • Habitat: tonzils • About 35 serovars is recognised (1-35) • Patogenic and nonpatogenic strains

  13. Pig Serotype 1 Serotype1/2 Serotype 2 Srotype 3 Serotype 4 Serotype 7 Serotype 8 Serotype 9 Serotype 16 Man Serotype 2 Pathogenic serotypes of S. suis

  14. Factors associated with patogenicity and virulence • Capsule (polysacharide) • Adherence • Receptors for IgG a albumins • Hemolyzin (suilysin) • Virulent proteins (MRP, EF, MRP*, EF*) • Other proteins (heat shock protein) • Genes responsible for virulence are known

  15. Disease in pigs and humans • Meningitis (serotype 2) • Endocarditis • Bronchopneumonia only in pigs • (Poly) Arthritis (serotype 1) only in pigs

  16. Enterococcus • Habitat: intestine of animals • E. faecium • E.faecalis • Vancomycine rezistence enterococci (VRE) from broilers • VRE - nosocomial (hospital) infection in humans • E. hirae

  17. Lactococcus • Starter cultures • L.lactis • L.cremoris • L.rafinolactis

  18. Grampositive rods forming endospores • Aerobic/facultatively anaerobic: • The genus Bacillus • Anaerobic: • The genus Clostridium

  19. Genus Bacillus • Group of B.cereus: • B.anthracis • B.cereus* • B.thuringiensis* • B.mycoides • B.pseudomycoides • Group of B.subtilis

  20. B.anthracis • Anthrax in domestic animals (cattle and sheep) • septisemia • Anthrax in man in 3 forms: • cutaneneous • gastrointestinal • pulmonary

  21. Anthrax treatment • 1. Antibiotics: • humans: ciprofloxacin (fluorochinolone) • cattle and sheep: penicillins • 2. Specific antibodies (hyperimmune serum): • humans : very limited • animals : very ofen in use

  22. B.cereus • toxinogenic B.cereus causes food poisoning in man: • 1) diarrhoeal syndrom • 2) emetic syndrom • toxinogenic B.cereus as feed poisoning in pigs

  23. Pathogenicity and virulence factors of toxinogenic B.cereus

  24. Laboratory diagnostics of enterotoxigenic B.cereus • Foodstaffs samples/ rectal swabs • Cultivation on selective media • Evidence of enterotoxins • BCET-REPLA for HBL toxin • ELISA for NHE

  25. Resistance to antimicrobial agents in B.cereus • Low susceptibility to penicillins and cephalosporins

  26. Genus Clostridium -pathogenic species • Neurotoxic species: • C.botulinum - botulism • C.tetani - tetanus • Histotoxic species:C.peringens, C.chauvoei, C.novyi, C.septicum, C.sordelii…. • Enteric and Enterotoxemic species: • C.perfringens -nekrotic enteritis (poultry, calves, piglets) • C.difficile - colitis (man, horse, pig, dog)

  27. Taxons of inserte sedis • F.: Erysipelothrichaceae • G.: Erysipelothrix • E. rhusiopathiae

  28. Listeria • Pathogenic species: • L.monocytogenes • L.ivanovii • virulence factors : • (LLO, PLC, internalin)

  29. L.monocytogenes • Human food borne infection since 1988 • Meningitis • Pregnant women- fetal infection- stillbirth • Neonatal menigitis • Animal listeriosis (sheep, cattle) – menigitis • abortions • mastitis

  30. L.ivanovii • Pathogen of sheep and other ruminants

  31. Non pathogenic species • L. innocua • L. seeligeri

  32. Erysipelothrix • E. rhusiopathiae • Habitat: tonsils of pigs • In pigs: • septisemia • „ diamond skin diseases“ – urtcal form • artritis • endocarditis

  33. E. rhusiopathiae • In fowl turkeys (septicemia):, chickens • In sheep (septicemia)

  34. Corynebacterium • C.pseudotuberculosis • In sheep and goats: caseous lymphadenitis • Corynebacterium renale, C.cystitidis , C. pilosum: bladder and kidney infections • Corynebacterium renale pyelonephritis in cows

  35. Nocardioform bacteria • Rhodococcus equi • pyogranulomatos pneumonia in foals • virulent strains • virulence plasmid • protein 18 kD Vap A and B

  36. Mycobacteria • G: Mycobacteriun • Patogenic species: • M.tuberculosis complex (one species ?) M. tuberculosis subsp. hominis (H) M.bovis M.bovis subsp.caprae M.microti (vole- rodents) M.africanum (H) • M.leprae – leprosy (H)

  37. Rod Mycobacterium -oprotunic pathogens : • M. avium-intracellulare complex • M.avium • M.avium subsp. avium • M.avium subsp. paratuberculosis • M.avium subsp. silvaticum • M.avium subsp. hominissuis • M.intracellulare • M.kansasii • M.simiae • M.marinum • M.xenopi

  38. Mycoplasma • Cattle • M.bovis,M. bovigenitalium • Pig • M.hyopneumonie, M.hyosynovie, M.hyorhinis • Poultry • M.gallisepticum • M.synoviae • M.meleagridis

  39. Mycoplasma hyopneumoniae • Enzootic pneumonia in pigs • aerogenic infection • chronic respirtory desease • Seroconversion after 2-4 weeks • Diagnostics: only PCR , serology suitable as herd test

  40. Mycoplasma haemosuis – new species • (Eperythrozoon suis) extracellular parasite of erythrocytes in pigs – eperythrozoonosis in piglets after weaning or in faterns • M.haemosuis – non detecteble on media in vitro – PCR detection during last decade

  41. M.haemosuis detected in • Blood of newborne piglets • Spleen of newborne piglets

  42. M.haemosuis positive newborne piglets • Clinical signs of low viability • High mortality (30%) during 3 days

  43. G+ bacteria 2008

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