Classification of bacteria Classification of bacteria DR.THAMINA SAYYED DR.THAMINA SAYYED REGISTRAR REGISTRAR MICROBIOLOGY MICROBIOLOGY KKUH KKUH

Bacterial cells

Classification System  3 Domains 1978 Carl Woese 1. Bacteria 1. Bacteria Unicellular prokaryotes with cell wall containing peptidoglycanUnicellular prokaryotes with cell wall containing peptidoglycan 2. Archaea 2. Archaea Unicellular prokaryotes with no peptodoglycan in cell wallUnicellular prokaryotes with no peptodoglycan in cell wall 3. Eukarya 3. Eukarya ProtistaProtista FungiFungi PlantaePlantae AnimaliaAnimalia

Comparing Prokaryotic and Eukaryotic Cells

Taxonomic Classification Categories  arranged in hierarchical order  species is basic unit DomainKingdom Phylum or Division ClassOrderFamilyGenusSpecies

Prokaryote Classification  Technologies used to characterize and ID prokaryotes and ID prokaryotes microscopic examination microscopic examination culture characteristics culture characteristics biochemical testing biochemical testing nucleic acid analysis nucleic acid analysis combination of the above is most accurate combination of the above is most accurate

Phenotypic & Genotypic classification

Phenotypic Characteristics for Identifying Prokaryotes  often does not require sophisticated equipment  can easily be done anywhere

Microscopic Phenotypic Exam  size and shape and arrangement enough information for diagnosis of certain infections enough information for diagnosis of certain infections  Gram stain distinguishes between Gram + and Gram – bacteria distinguishes between Gram + and Gram – bacteria narrows the possibilities quickly narrows the possibilities quickly

Microscopic Phenotypic Exam  special stain allows for the distinction of microorganisms with unique characteristics allows for the distinction of microorganisms with unique characteristics capsulecapsule acid fast staining detects the waxy presence of Mycobacterium tuberculosisacid fast staining detects the waxy presence of Mycobacterium tuberculosis Capsule staining Acid fast staining of M. tuberculosis

CELL WALL 11 Gram positive cell wall  Consists of a thick, homogenous sheath of peptidoglycan nm thick a thick, homogenous sheath of peptidoglycan nm thick tightly bound acidic polysaccharides, including teichoic acid and lipoteichoic acid tightly bound acidic polysaccharides, including teichoic acid and lipoteichoic acid cell membrane cell membrane  Retain crystal violet and stain purple Gram negative cell wall  Consists of an outer membrane containing lipopolysaccharide (LPS) an outer membrane containing lipopolysaccharide (LPS) thin shell of peptidoglycan thin shell of peptidoglycan periplasmic space periplasmic space inner membrane inner membrane  Lose crystal violet and stain pink from safranin counterstain

12 Gram Positive Gram Negative

13 Crystal violet Gram's iodine Decolorise with acetone Counterstain with e.g. methyl red Gram-positives appear purple Gram-negatives appear pink The Gram Stain

15 Gram-positive rods Gram-negative rods Gram-positive cocci Gram-negative cocci

Metabolic Phenotypic Exam  cultural approaches required for positive diagnosis of infection required for positive diagnosis of infection isolation and ID of pathogen isolation and ID of pathogen accuracy, reliability, and speed accuracy, reliability, and speed  methods used include culture characteristics culture characteristics biochemical reactions process biochemical reactions process

Serological Testing Phenotypic Exam  serological testing uses ELISA testing fast and easy to use fast and easy to use

Classification of bacteria

Classification of medically significant bacteria  I.Thick rigid walled cells A. Free living extracellular A. Free living extracellular 1.Gram positive 1.Gram positive a.Cocci Staphylococcus - abcess a.Cocci Staphylococcus - abcess Streptococcus - puemonia, Streptococcus - puemonia, Pharyngitis cellulitis Pharyngitis cellulitis b.Spore forming rods b.Spore forming rods Aerobic Bacillus - Anthrax Aerobic Bacillus - Anthrax Anaerobic Clostridium - tetanus,gas gangrene Anaerobic Clostridium - tetanus,gas gangrene botulism botulism

c.Non spore forming rods ( GRAM POSTIVE CONTD) 1-Non filamentous Cornybacterium – Diphtheria 1-Non filamentous Cornybacterium – Diphtheria Listeria - meningitis Listeria - meningitis 2.Filamentous Actinomycetes – Actinomycosis 2.Filamentous Actinomycetes – Actinomycosis Nocardia - Nocardiosis Nocardia - Nocardiosis

 2.Gram negative A.Cocci Neisseria -Gonorrhoea, A.Cocci Neisseria -Gonorrhoea, meningitis meningitis B.Rods B.Rods 1.Facultative 1.Facultative a. Straight a. Straight 1.Respiratory org. Haemophillus- meningitis 1.Respiratory org. Haemophillus- meningitis Bordatella-Whooping cough Bordatella-Whooping cough Legionella- Pneumonia Legionella- Pneumonia 2.Zoonotic Brucella – Brucallosis 2.Zoonotic Brucella – Brucallosis Francisella –Tularemia Francisella –Tularemia Pasteurella –Cellulitis Pasteurella –Cellulitis Yersinia - Plague Yersinia - Plague

 3.enteric & related ( GRAM NEGATIVE CONTD) E.coli - UTI,Diarrhoea E.coli - UTI,Diarrhoea Enterobacter – UTI Enterobacter – UTI Serratia – Pneumonia Serratia – Pneumonia Klebsiella – Pneumonia.UTI Klebsiella – Pneumonia.UTI Salmonella – enterocolitis,typhoid fever Salmonella – enterocolitis,typhoid fever Shigella – Enterocolitis Shigella – Enterocolitis Proteus – UTI Proteus – UTI b. Curved b. Curved Campylobacter – Entericolitis Campylobacter – Entericolitis helicobacter – Gastritis,Peptic ulcer helicobacter – Gastritis,Peptic ulcer Vibrio - Cholera Vibrio - Cholera

(Gram negative) (Gram negative)  C.Aerobic Pseudomonas – pneumonia,UTI  D. Anaerobic Bacteroids – peritonitis 3.ACID FAST 3.ACID FAST MYCOBACTERIUM - Tuberculosis & Leprosy MYCOBACTERIUM - Tuberculosis & Leprosy

 B. Non free living obligate intracellular parasites 1.Rickettsia – Rocky mountain spotted fever 1.Rickettsia – Rocky mountain spotted fever Typhus, Q fever Typhus, Q fever 2.Chlamydia urethritis, trachoma. Psittacosis 2.Chlamydia urethritis, trachoma. Psittacosis

Flexible thin walled Flexible thin walled Spirochaetes - Treponema – Syphilis Spirochaetes - Treponema – Syphilis Borrelia – Lyme disease Borrelia – Lyme disease Leptospira - leptospirosis Leptospira - leptospirosis Wall- less cells Wall- less cells Mycoplasma - pneumonia Mycoplasma - pneumonia

Subtyping & Its applications Subtyping & Its applications  To distinguishinguish between strains of different species  Biotyping  Serotyping  Antimicrobial susceptibility system  Bacteriophage typing  Bacteriocin typing

Genotypic Characteristics for Identifying Prokaryotes  the use of genotypic testing has increased with the availability of technology  genotypic testing is particularly useful in the case of organisms that are difficult to identify  several techniques include gene probes gene probes PCR PCR sequencing rRNA sequencing rRNA

 gene probes single stranded DNA that has been labeled with a identifiable tag, such as a fluorescent dye single stranded DNA that has been labeled with a identifiable tag, such as a fluorescent dye are complementary to target nucleotide sequences are complementary to target nucleotide sequences unique in DNA of pathogenunique in DNA of pathogen

 PCR: polymerase chain reaction used to detect small amounts of DNA present in a sample (blood, food, soil) used to detect small amounts of DNA present in a sample (blood, food, soil) the PCR chain reaction is used to amplify the amount of DNA present the PCR chain reaction is used to amplify the amount of DNA present Genotypic Characteristics used in Classifying Prokaryotes( non culture methods)  sequencing ribosomal RNA of particular use for identifying prokaryotes impossible to grow in a culture of particular use for identifying prokaryotes impossible to grow in a culture focus is place on the 16S molecules of the RNA because of it’s size focus is place on the 16S molecules of the RNA because of it’s size approximately 1500 nucleotidesapproximately 1500 nucleotides once the 16S molecule is sequenced, it can then be compared to the sequences of known organisms once the 16S molecule is sequenced, it can then be compared to the sequences of known organisms

Genotypic Characteristics used in Classifying Prokaryotes  comparison of nucleotide sequences differences in DNA sequence can assist in determination of divergence of evolutionary path for organisms differences in DNA sequence can assist in determination of divergence of evolutionary path for organisms  DNA hybridization single strands of DNA anneal single strands of DNA anneal  16S ribonucleic acid comparing sequence of ribosomal RNA comparing sequence of ribosomal RNA  relatedness to other organisms can be determined using numerical taxonomy determined by the percentage of characteristics two organisms have in common determined by the percentage of characteristics two organisms have in common