Transcript Listeria monocytogenes
1 Listeria & Erysipelothrix Filename: Listeria.ppt
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2 Outline Microbes –
Corynebacterium, Listeria, Erysipelothrix
Diseases – Diphtheria, Listeriosis, Erysipeloid 4/27/202 0
3 Listeriosis 4/27/202 0
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Listeria monocytogenes
short , motile,non-spore - forming, Grm + rods, - hemolytic, looks like Group B streptococcus but group B is catalase neg and non-motile.
found in wild and domestic animals excreted into soils healthy human carriers 5-10 % source of infection is food and animal contact.
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Listeria I nfections
Neonatal sepsis or meningitis Spontaneous abortion or still birth Sepsis or meningitis in immunocompromised patients Puerperal sepsis Persons at risk: Pregnant, post partum, new born, organ transplants 4/27/202 0
6 Listeriosis Disease of humans – Sepsis – Meningitis + encephalitis 25% mortality 4/27/202 0
7 Listeria Pathogenesis Ingested raw contaminated food Penetrates cell of intestine common event most have T cells Facultative intracellular pathogen Immunocompromised host Transmitted congenitally 4/27/202 0
8 Listeriosis Diagnosis Monocytosis – Peripheral blood & cerebrospinal fluid Gram stain – Gram positive rods in CFS Culture – Blood, CSF, skin lesions 4/27/202 0
9 Listeria: Virulence Factors Internalin an invasion factor controlled by the inl A gene The organisms are taken into the cell by forced phagocytosis , become enclosed in a vesicle and rupture it.
Listeriolysin - alpha hemolysis hly gene. Lecithinase - hemolysin Phospholipase 4/27/202 0
10 Listeria: Food poisoning MILK and dairy products. This species grows at refrigerator temp. 5-12 o C Isolated by cold enrichment.
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11 Test for Listeria in Milk Add fluorescent-labelled antibodies specific for
Listeria monocytogenes
to milk Pass through a flow cytometer. fluid is passed through a small opening Listeria detected by a laser beam NO CULTURE NEEDED!!!
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12 Listeriosis Prevention Persons at risk avoid soft cheeses and unpasteurized milk and processed meat that cannot be cooked.
thoroughly cook all meats especially hot dogs – left over meat should be cooked to steaming.
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13 Listeriosis Control Hygienic food processing – contaminated vegetables – vinegar in salads Antimicrobial agents – Not cephalosporins – Ampicllin + aminoglycoside – bacteriostatic 4/27/202 0
14 Erysipeloid 4/27/202 0
15 Erysipelothrix pathogenesis Skin lesions – fingers or hand – violet or wine coloured Occasionally septicemia – endocarditis – afebrile arthritis 4/27/202 0
16 Erysipelothrix rhusiopathiae Gram positive rods Grow aerobically – prefer 7% carbon dioxide Non motile Non hemolytic Produce hydrogen sulfide 4/27/202 0
17 Erysipelothrix Epidemiology Found in mammals, poultry & fish Farmers, vets, slaughterhouse workers, fish handlers 4/27/202 0
18 Erysipelothrix Diagnosis & Control Diagnosis – Typical lesions – Occupation – Blood culture if sepsis Control – Self limiting – Penicillin if complications 4/27/202 0
19 The End 4/27/202 0
20 Performance Objectives Key terms, concepts short answers 4/27/202 0
Key Terms 21 4/27/202 0
Key Terms 22 4/27/202 0
23 Key Organisms
Corynebacterium
Listeria
Erysipelothrix
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24 Key Concepts 4/27/202 0
25 Epidemiology of Listeriosis Disease/bacterial factors Transmission Who is at risk Geography/ season Incidence Modes of control 4/27/202 0
26 Short Answers Construct a table of the virulence factors associated with listeriosis and the biological activity of each Describe the clinical manifestations of listeriosis Construct a table listing the common Corynebacteria and the associated diseases.
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