Classification of Bacteria

Transcription

1 Classification of Bacteria

2 MICROBIOLOGY -TAXONOMY Taxonomy is the system to classify living organisms Seven groups kingdom, phylum or div, class, order, family, genus, species Binomial system of nomenclature genus name followed by spp name

3 TAXONOMY Systemic classification & categorization of organisms in to ordered groups Bacterial classification according to phenotypic features a) Morphology ( cocci, bacilli, spirochaetes, ) b)staining properties ( Gram +ve, Gram ve,) Cultural requirements (aerobic, facultative anaerobe,, anaerobe ) Biochemical reaction sugar fermentation reaction Antigenic structure (serotypes) Genotypic taxonomy DNA homology guanine & cytosine content (GC )

4 GRAM STAINING

5

6

7

8

9 Classification of Gram positive bacteria Cocci aerobes clusters staphylococcus chains/pairs streptococcus - anaerobes chains/clusters - peptostreptococcus

10

11 Classification of Gram positive bacteria Bacilli aerobes sporing Bacillus B. anthracis non sporing Corynebacterium, Lactobacillus, Nocardia, - anaerobes sporing Clostridium non sporing Actinomyces, Propionibacterium

12 Classification of Gram negative bacteria Cocci aerobes Neisseria, - anaerobes Veillonella

13 Classification of Gram negative bacteria Bacilli aerobes or facultative anaerobes a.parvobacteria Haemophilus, Brucella, Bordetella, Yersinea, Pasteurella b.enterobacteria Escherichia, Klebsiella,Proteus, Serratia,Salmonella, Shigella, c. Vibrio Vibrio, Campylobacter d. Legionella -

14 Classification of Gram negative bacteria Bacilli anaerobes Bacteroides, Porphyromonas, Prevotella

15 BACTERIAL IDENTIFICATION Macroscopic morphology Microscopic morphology Physiological/ biochemical characteristics Chemical analysis of cell wall Serological analysis Genetic & molecular analysis

16 NORMAL FLORA Definition: Bacteria & fungi which are permanent residents of certain body sites. They are not harmful when present in that location, but most of them become serious pathogens when transferred to deeper tissues. Many are therefore considered opportunistically pathogenic. The establishment of resident bacteria begins during birth

17 Commensals = Normal flora Colonizers = Acquisition of a new organism. After the new organism colonizes (i.e., attaches and grows, usually on a mucosal mem brane), it may cause an infectious disease or it may be eliminated by our host defenses. Carrier = An individual harbors a potential pathogen and therefore can be a source of infection of others

18 NORMAL FLORA DISTRIBUTION Common sites in contact with outside world Skin, eye,mouth,upper resp tract, GIT, urogenital tract Sterile sites internal organs & systems spleen, pancreas, liver, bladder, CNS

19 NORMAL FLORA ANATOMIC SITE Bacteroides Candida albicans Clostridium sp. Corynebacterium sp. Haemophilus sp. Lactobacillus sp. Neisseria sp. S. aureus S. epidermidis Colon,throat,vagina Mouth,colon,vagina Colon Nasopharynx,skin, vagina Nasopharynx,conjunctiva Mouth, colon,vagina Mouth, Nasopharynx Nose, skin Skin,nose,mouth,vagina, urethra

20 Normal Flora of Skin Staphylococcus aureus, and Staph. epidermidis, Micrococci Propionibacterium acnes, Diphtheroids (Coryneforms)

21 Respiratory Tract Flora Hostile to most bacteria because of mucous The upper respiratory tract Staphylococcus aureus, Staph. epidermidis, Streptococcus pneumoniae, Strept. mutans, Strept. viridans, Haemophilous influenzae, Moraxella catarrhalis, Neisseria sicca, Corynebacterium sp.

22 Teeth Gingival Crevice - Fusobacterium sp. (G-, anaerobic, elongated) Borrelia sp. (G--, anaerobic, spirillum) B. vincentii causes trench mouth (Vincent's Disease) in predisposed individuals) Surface - Leptotrichia buccalis (G-, anaerobic, filamentous) Lactobacillus sp. (G+ bacilli) Streptococcus (G+, cocci)

23 Dental Caries (Decay Sites) Compacted food and bacteria is called Dental Plaque Streptococcus mutans produces glucan (glycocalyx, Dextran) Lactobacillus sp. ferment sucrose inside the plaque into lactic acid Anaerobes- Bacteroides,Fusobacterium,actinomyces

24 Gastrointestinal Tract Flora Mouth - Viridans streptococci 50% Spirochaetes borrelia, treponema, Anaerobes bacteroides spp,fusobacterium, lactobacillus spp, prevotella spp, Actinomyces Esophagus, Stomach, Duodenum, Jejunem, Ileum (last part), Colon(10 11 ) : Bacteroides sp., Peptostreptococcus sp., Clostridium sp. enterobacteriaceae,pseudomonas, protozoa

25 Newborns: A. Breast-fed babies - Bifidobacterium, Lactobacillus B. Formula-fed babies - Mixed flora

26 Urogenital Flora First month of life -Lactobacillus spp, From I month of age to puberty --diphtheroids, S epidermidis, streptococci, and E coli At puberty -- Lactobacillus spp, L.acidophilus, corynebacteria, peptostreptococci, staphylococci, streptococci, and Bacteroides Menopause --prepubescent flora, Yeasts (Torulopsis and Candida) Gp B Strept,

27 NORMAL FLORA UROGENITAL TRACT Adult women -Lactobacillus spp, Before puberty & after menopause lactobacilli rare

28 In the anterior urethra S epidermidis, enterococci, and diphtheroids --frequently E coli, Proteus, and Neisseria (nonpathogenic species) --occasionally

29 Conjunctival Flora corynebacteria, neisseriae, and moraxellae, Staphylococci, streptococci & Haemophilus spp. Tears contain lysozyme, help limit bacterial population of conj

30 Diseases due to normal flora

31 NORMAL FLORA BENEFICIAL FUNCTIONS 1-Due to increased no in lower GIT & mouth compete for nutrients with invading pathogens 2- Some bacteria of bowel produce antibacterial subs 3- Bacterial colonization of newborn infant acts as a powerful stimulus for development of immune system 4- Bacteria of gut produce vit K

32 NORMAL FLORA harmful effects When org are displaced from normal site in body to abnormal site eg: skin flora - Endocarditis Urethral flora - UTI Gut flora - Peritonitis Mouth flora Fascial soft tissue infection When individual are immunocopromised, normal flora can overgrow & become pathogenic

33 Death of normal flora diminished population of normal flora due to antibiotic therapy cause overgrowth of C. difficile - Psuedomembranous colitis

34