introduction to bacteria.pptx

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INTRODUCTION TO BACTERIA Dr. Nilanthi Dissanayake (MBBS, Dip. Micro, MD Micro) Department of Microbiology Faculty of Medicine University of Peradeniya

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INTRODUCTION TO BACTERIA

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Page 1: INTRODUCTION TO BACTERIA.pptx

INTRODUCTION TO BACTERIA

Dr. Nilanthi Dissanayake (MBBS, Dip. Micro, MD Micro)Department of Microbiology

Faculty of MedicineUniversity of Peradeniya

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OBJECTIVES

1. Major morphological and biological characteristics of infective bacteria that determine visualisation/ID

2. Basis of classification and means by which recognised as a cause of disease in a patient

OBJECTIVES

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STRUCTURE

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HABITAT? Where are bacteria found

EVERY WHERE BUT – most are non pathogenic

Skin flora Space

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IMPORTANCE• Basic life form

• Waste degradation

• Industry

• Antibiotic production

• Vaccine production

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CLASSIFICATION• Morphology

A- BacilliB,C,D- CocciE- Spiral

• Stain characteristics

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IDENTIFICATION• Culture

• Staining characteristics

• Antigen detection

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• Biochemical tests

• Nucleic acid detection

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HOST PARASITE RELATIONSHIP

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STAPHYLOCOCCI

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OBJECTIVES

• Habitat, main mode/s of transmission• Morphology and growth characteristics in

relation to ID• Virulence factors, pathogenicity and main

clinical diseases• Principles of treatment and prevention

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Staphylococci……• Gram positive cocci in clumps

• Ubiquitously found in humans, animals and in the environment

• Important human pathogen

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Staphylococci……• Several species• Classified using coagulase

Positive – S.aureus

Negative- Coagulase negative Staphylococci (CNS)

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S.aureus…… Habitat and transmission

• Normal flora of human and animals

• Abundant in ‘sweaty’ hairy areas – nose, axilla, scalp Skin scales – (10-100,000)/cm2 of skin

• Survives for long periods in environment

• TransmissionDirect or indirect contact

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S.aureus….. Virulance and disease• Several virulence factors eg. Adhesins, hyaluronidase, leucocidin, coagulase, staphylokinase, haemolysins

Toxins – exfoliatin, enterotoxins, Panton Valentine Leucicidin (PVL)

• DiseaseLocalSystemicToxin related

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Antibiotic Treatment• Development of resistance Penicillinase production

Change of Penicillin binding Proteins or the binding target • Range of antibiotics which can be used for treatment

β lactams - penicillins, cephalosporins, carbapenemsMacrolides – erythomycin, azithromycin,

clarithromycinGlycopeptides – vancomycin, teicoplaninOthers – quinolones, rifampicin, linelozid,

daptomycin

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Coagulase negative staphylococci….• Many species, but only few are important

S.epidermidisS.saprophyticus

• S.saprophyticus – common cause of Urinary tract infections in females

- very sensitive to antobiotics

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• S.epidermidis- Skin commensal- Not a primary pathogen-Forms biofilms on prosthetic material