Medical Bacteriology
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MEDICAL BACTERIOLOGY CLASSIFICATION OF BACTERIA In 1923, David Bergey, Professor of bacteriology at the University of Pennsylvania, and four colleagues published a classification of bacteria called the Bergey’s Manual of Systematic Bacteriology. It contains descriptions of all procaryotic species. The first volume of the second edition has been published recently. The first edition of bergey’s manual of systematic bacteriology The system given in the first edition of Bergey’s Manual is primarily phenetic. It contains 33 sections in the four volumes. Volume 1 (1984) - It describes Gram-negative Bacteria of general, medical or industrial importance . Volume 2 (1986) – It illustrates Gram-positive Bacteria other than Actinomycetes. Volume 3 (1989) - It describes Archaeobacteria, Cyanobacteria, and remaining Gram- negative Bacteria. Volume 4 (1989) – It illustrates Actinomycete. The second edition of bergey’s manual of systematic bacteriology There has been enormous progress in procaryotic taxonomy since 1984. In particular, the sequencing of rRNA, DNA and proteins has made phylogenetic analysis of prokaryotes feasible. As a consequence, the second edition of Bergey’s Manual was published based on phylogenetic characters. The second edition is made of 5 volumes. It have more ecological information about individual taxa. The second edition will not group all the clinically important prokaryotes together. Instead, pathogenic species will be placed phylogenetically and thus scattered throughout the following five volumes. Volume 1 (2001) -It explains the Archaea and the deeply branching and phototrophic Bacteria. Volume 2 (2005) – it describes the characters of Proteobacteria. Volume 3 (2009) - It clearly depicts the Firmicutes. Volume 4 (2011) - The nature of The Bacteroidetes, Spirochaetes, Mollicutes, Acidobacteria, Fibrobacteres, Fusobacteria, Dictyoglomi, Gemmatimonadetes, Lentisphaerae, Verrucomicrobia, Chlamydiae, and Planctomycetes. Volume 5 (2012) - It describes The Actinobacteria Summary of Bergey’s Manual of Systematic Bacteriology 2nd edition Volume 1. The Archaea and the Deeply Branching and Phototrophic Bacteria Domain Archaea Phylum Crenarchaeota Thermoproteus, Pyrodictium, Sulfolobus Phylum Euryarchaeota Class I. Methanobacteria- Methanobacterium Class II. Methanococci- Methanococcus Class III. Halobacteria -Halobacterium, Halococcus Class IV. Thermoplasmata -Thermoplasma, Picrophilus Class V. Thermococci -Thermococcus, Pyrococcus Class VI. Archaeoglobi- Archaeoglobus Class VII. Methanopyri -Methanopyrus Domain Bacteria Phylum Aquificae -Aquifex, Hydrogenobacter Phylum Thermotogae -Thermotoga, Geotoga Phylum Thermodesulfobacteria- Thermodesulfobacterium Phylum “Deinococcus-Thermus” Deinococcus, Thermus 104 Phylum Chrysiogenetes- Chrysogenes Phylum Chloroflexi- Chloroflexus, Herpetosiphon Phylum Thermomicrobia- Thermomicrobium Phylum Nitrospira- Nitrospira Phylum Deferribacteres- Geovibrio Phylum Cyanobacteria- Prochloron, Synechococcus, Pleurocapsa, Oscillatoria, Anabaena, Nostoc, Stigonema Phylum Chlorobi- Chlorobium, Pelodictyon Volume 2. The Proteobacteria Phylum Proteobacteria Class I – Alphaproteobacteria- Rhodospirillum, Rickettsia, Caulobacter, Rhizobium, Brucella, Nitrobacter, Methylobacterium, Beijerinckia, Hyphomicrobium Class II - Betaproteobacteria -Neisseria, Burkholderia, Alcaligenes, Comamonas, Nitrosomonas, Methylophilus, Thiobacillus Class III – Gammaproteobacteria- Chromatium, Leucothrix, Legionella, Pseudomonas, Azotobacter, Vibrio, Escherichia, Klebsiella, Proteus, Salmonella, Shigella, Yersinia, ` Haemophilus Class IV – Deltaproteobacteria- Desulfovibrio, Bdellovibrio, Myxococcus, Polyangium Class V - Epsilonproteobacteria- Campylobacter, Helicobacter Volume 3. The Low G - C Gram-Positive Bacteria Phylum Firmicutes Class I. Clostridia- Clostridium, Peptostreptococcus, Eubacterium, Desulfotomaculum, Heliobacterium, Veillonella Class II. Mollicutes- Mycoplasma, Ureaplasma, Spiroplasma, Acholeplasma Class III. Bacilli- Bacillus, Caryophanon, Paenibacillus, Thermoactinomyces, Lactobacillus, Streptococcus, Enterococcus, Listeria, Leuconostoc, Staphylococcus Volume 4. The High G- C Gram-Positive Bacteria Phylum Actinobacteria Class Actinobacteria- Actinomyces, Micrococcus, Arthrobacter, Corynebacterium, Mycobacterium, Nocardia, Actinoplanes, Propionibacterium, Streptomyces,Thermomonospora, Frankia, Actinomadura, Bifidobacterium Volume 5. The Planctomycetes, Spirochaetes, Fibrobacteres, Bacteriodetes, and Fusobacteria Phylum Planctomycetes - Planctomyces, Gemmata Phylum Chlamydiae- Chlamydia Phylum Spirochaetes -Spirochaeta, Borrelia, Treponema, Leptospira Phylum Fibrobacteres- Fibrobacter Phylum Acidobacteria- Acidobacterium Phylum Bacteroidetes- Bacteroides, Porphyromonas, Prevotella, Flavobacterium, Sphingobacterium, Flexibacter, Cytophaga Phylum Fusobacteria- Fusobacterium, Streptobacillus Phylum Verrucomicrobia- Verrucomicrobium Phylum Dictyoglomi -Dictyoglomus 55. CLASSIFICATION OF PATHOGENIC BACTERIA Bergey's Manual of Determinative Bacteriology This book is a collection of brief descriptions of bacteria and detailed tables of differential characteristics of bacterial species described and cultured as of January 1991. Now this book is in 9th edition. It was published in 1994. Determinative manual serving as a reference to aid in the identification of unknown bacteria. Information is arranged strictly based on phenotypic characteristics of bacteria. The bacteria are divided into 35 groups.These groups are not meant to be formal taxonomic ranks. 105 The classification described below is based on the Bergey’s manual determinative Bacteriology. GROUP 1: THE SPIROCHETES Gram-negative helical shaped cells that are highly flexible. Motile by periplasmic flagella Chemoorganotrophic Anaerobic, Microaerophilic, Facultative anaerobic or Aerobic Some are pathogenic to human and animals. Important Genus Borrelia Spirochaeta Leptospira Treponema GROUP 2: AEROBIC/MICROAEROPHILIC, MOTILE, HELICAL/VIBRIOID Gram Negative Cells are helical or Vibrioid Motile by polar flagella Aerobic or Microaerophilic,having a respiratory type of metabolism Chemoorganotrophic Some are pathogenic to animals or humans. Some are predatory on other microorganisms. Important Genus Campylobacter Helicobacter Group 4: GRAM-NEGATIVE AEROBIC/MICROAEROPHILIC RODS AND COCCI Chemoorganotrophic heterotrophs Occur in soil, fresh water, or marine environments and oral cavity of human and animals Some are pathogenic for animals or humans. Important Genus Alcaligenes Legionella Alteromonas Moraxella Bordetella Neisseria Brucella Pseudomona Flavobacterium Group 5: FACULTATIVELY ANAEROBIC GRAM-NEGATIVE RODS Chemoorganotrophic heterotrophs Occur either free-living or in association with animal, human, or plant hosts. Some are pathogenic. Important Genus Citrobacter Aeromonas Escherichia Plesiomonas Hafnia Photobacterium Klebsiella Vibrio Proteus Actinobacillus Salmonella Haemophilus Serratia Pasteurella Shigella Streptobacillus Yersinia 106 Group 6: GRAM-NEGATIVE, ANAEROBIC, STRAIGHT, CURVED,AND HELICAL RODS Chemoorganotrophic heterotrophs Obtain energy by anaerobic respiration or by fermentation. Important Genus Bacteroides Fusobacterium Porphyromonas Group 8: ANAEROBIC GRAM-NEGATIVE COCCI Chemoorganotrophic heterotrophs Have a strictly fermentative type of metabolism. Important Genus Veillonella Group 9: THE RICKETTSIAS AND CHLAMYDIAS Obligate intracellular parasite May be rod-shaped, coccoid, or pleomorphic Many species are pathogenic. Important Genus Rickettsia Chlamydia Group 17: GRAM POSITIVE COCCI Chemoorganotrophic Mesophilic Non-spore forming cocci Aerobic cocci that occur in pairs, clusters, or tetrads Facultatively Anaerobic or Microaerophilic Cocci and Strictly Anaerobic Cocci also occur in pairs, clusters, or tetrads. Important Genus Enterococcus Leuconostoc Micrococcus Peptococcus Peptostreptococcus Staphylococcus Streptococcus Group 18: ENDOSPORE-FORMING GRAM-POSITIVE RODS AND COCCI Bacteria that produce heat-resistant endospores. Mostly motile rods or filaments Strict Aerobes, Facultative Anaerobes, Microaerophils, or Strict Anaerobes. Bacillus Clostridium Group 19: REGULAR, NONSPORING GRAM-POSITIVE RODS Rod-shaped cells Non-sporing, Nonpigmented, Mesophiles Chemoorganotrophic Fermentative, Saccharolytic Microaerophils 107 Aerobes or Facultative Anaerobes Strict Aerobes Lactobacillus Erysipelothrix Listeria Group 20: IRREGULAR, NON-SPORING GRAM-POSITIVE RODS Irregular rods Some may exhibit club-shaped forms, branched filamentous elements, or mixtures of rods or filamentous and coccoid forms Strictly aerobic or Facultatively anaerobic to Microaerophilic or strictly Anaerobic Some are pathogens of animals or plants. Acetobacterium Actinomyces Bifidobacterium Brevibacterium Corynebacterium GROUP 21 : THE MYCOBACTERIA Aerobic Nonmotile Nonsporing Slow growing rod shaped bacteria Acid Fast Bacterium Branched filaments are formed occasionally. No Aerial Mycelium is formed. Important genus : Mycobacterium GROUP 22-29 THE ACTINOMYCETES Gram-positive bacteria that form branching filaments or hyphae Some are motile GROUP 22 NOCARDIFORM ACTINOMYCETES Sub group 1 Mycolic Acid Containing Bacteria Rhodococcus Nocardia. Subgroup 2 Pseudonocardia And Related Genera Pseudonocardia Subgroup 3 : Nocardioides Terrabacter. Subgroup 4 : Jonesia GROUP 30 MYCOPLASMAS Pleomorphic cells devoid of cell walls. Growth on agar shows characteristic “fried egg” appearance Requires sterols for growth May show Gliding motility Facultative anaerobic to Obligatory