Survey of Microbes Part I: Important prokaryotes

But first… a word on shape, arrangement and size SHAPES: 1. ____________ – spherical, ball shaped 2. ____________ - rod 3. _________________– helical, comma (vibrio), twisted rod (spirillum, rigid with lophotrichous flagella), spirochete (flexible with periplasmic flagella) Also… intermediate shapes like coccobacillus cells can be thin (filamentous) Cells can be pleomorphic (species can have >1 form such as Corynebacterium diphtheriae)

arrangements of bacteria Pairs (2 like diplococci, diplobacilli) Tetrads (4 cells in packet) Sarcinae (balls or blocks of 8, 16, 32 cells) Chains (streptococci; streptobacilli) Clusters (Micrococcus, Staphylococcus) Palisades arrangement (Corynebacteria)

streptococcidiplobacillusspirochetespirillum

size

7 Bacterial Taxonomy Based on Bergey’s Manual Bergey’s Manual of Determinative Bacteriology – five volume resource covering all known prokaryotes ◦Classification based on genetic information – phylogenetic ◦Two domains: Archaea and Bacteria ◦Five major subgroups with 25 different phyla

8 Major Taxonomic Groups of Bacteria Domain ____________ – primitive, adapted to extreme habitats and modes of nutrition Domain Bacteria: ◦Phylum Proteobacteria – Gram-negative cell walls ◦Phylum Firmicutes – mainly gram-positive with low G + C content ◦Phylum Actinobacteria – Gram-positive with high G + C content

Figure 4.27 Universal phylogenetic tree 9

IMPORTANT GRAM POSITIVE BACTERIA

Soil bacteria: Bacillus Clostridium (some pathogens) Lactic acid bacteria: Lactococcus, Lactobacillus, Acidophilus Several human pathogens: Staphylococcus (S. aureus) Streptococcus (S. pyogenes, S. pneumoniae) Mycobacterium (M. leprae and M. tuberculosis) Corynebacterium Listeria monocytogenes Others: Propionibacterium Streptomyces Mycoplasma! (no cell wall, but it’s grouped with G+) Important Gram positive bacteria

Staphylococcus Genus: staphylo=“grape clusters” S. epidermidis – opportunistic pathogen; no virulence factors; natural flora S. aureus – hemolytic, coagulase, invasive; flora of the nose but still a pathogen Many diseases: endocarditis, pneumonia, meningitis, arthritis, intoxications such as ______________________ and food poisoning; more often cuteneous: ◦pimples/boils/abscesses/carbuncles, pink eye ◦scalded skin syndrome, ◦impetigo. 1a.) Gram + cocci

BOIL CARBUNCLE SCALDED SKIN SYNDROME IMPETIGO Strep. pyogenes? Endocarditis

Virulence factors of Staph Pathogenic effects: mostly associated with ________________________ Diagnostic marker localized clotting Prevents bacteria from being cleared from host Kills leukocytes so that bacteria are not phagocytosed Form pus and acne 1a.) Gram + cocci --Staph

Current estimate: >60% of hospital acquired S. aureus infections are MRSA Many strains are MDR!!

TSN, The Surveillance Network (data include hospital infections); NNIS, National Nosocomial Infections Surveillance System (data include only intensive care units); SENTRY, includes only skin and soft tissue infections. Percentage of Staphylococcus aureus isolates resistant to methicillin in national surveys, United States, 1999–2004. (source: Klein et al EID)

Hospitalizations and Deaths Caused by Methicillin-Resistant Staphylococcus aureus, United States, 1999–2005 Figure 1. Estimated methicillin-resistant Staphylococcus aureus (MRSA)–related hospitalization rates, United States, 1999–2005. Rates are no. MRSA-related discharges/1,000 hospitalizations. Error bars represent 95% confidence intervals. (source: Klein et al EID)

Streptococcus 1. Group A Strep = ____________ Strep throat, pharyngitis ◦Secondary: Scarlet fever (systemic rash); Rheumatic fever (heart valves, arthritis) Cuteneous infections: Impetigo (older children), pyoderma, acne, Erysipelas – AKA “St. Anthony’s Fire”; Toxic shock syndrome ◦____________ ____________ ; “flesh eating bacteria” All are mediated by various virulence factors – esp. ____________ 1a.) Gram + cocci

Strawberry tongue – Scarlet fever Strep throat 1a.) Gram + cocci --Strep

Streptococcus Streptococcal toxic shock syndrome (STSS), causes blood pressure to drop rapidly and various organs to fail. About 20% of patients with necrotizing fasciitis and more than half of those with STSS will die. Generally, the mortality rate for other forms of invasive group A streptococcal disease is 10-15%. 1a.) Gram + cocci --Strep

PYODERMA (S. aureus or S. pyogenes)

Virulence factors of Strep ____________ : due to secretion of many enzymes and toxins including: ◦____________ : lyse red blood cells ◦____________ : breaks down collagen (cement of connective tissue: helps organism spread) 1a.) Gram + cocci --Strep

Other pathogenic Streptococci ________________________ : causes dental caries (cavities) ____________________________ (often called pneumococcus) carried in upper respiratory tract and nasopharynx of humans 15% of children and 5% of adults are “carriers” grow in pairs (NOT in long chains) most common cause of pneumonia and otitis media (middle ear infection) 1a.) Gram + cocci --Strep

Clostridium ____________ ____________ (cannot grow in oxygen) rod shaped bacteria contain ____________ : resistant to heat and chemicals; spores are introduced into injury or anaerobic wound or ingested (botulism) ◦ spores germinate and active bacteria multiply 1b.) Gram + rods --Clostridium

Medically important species C. tetani: ____________ ◦neurotoxin: called tetanospasmin (a dot the size of a period-kills 30!) ◦blocks muscles relaxation: muscles spasm and contract ◦contractions: tear muscles/cause compression fraction of vertebrae  death from spasms of respiratory muscles  vaccine (DPT): inactivated toxin used to stimulate antibodies C. difficile: ____________ ____________ often caused when antibiotic therapy alters microflora in intestines and allows for growth of this organism C. perfringens: causes ______________________ (severe tissue death); also foodborne diarrhea 1b.) Gram + rods --Clostridium

Medically important species C. botulinum: ____________________. grows in anaerobic environments (canned foods): discard bulging cans! Produces toxin: MOST potent of ALL toxins: specific for nerve endings (synapses) Blocks acetylcholine (neurotransmitter): nerve impulses blocked! Botulism disease progression: Initial symptom: blurred vision and nausea flaccid paralysis: respiratory and cardiac failure slow recovery: nerve endings regenerate; respiratory support: antibiotics are of no use! Prevention: Toxin is destroyed by boiling and nitrites in food prevent bacterial growth A word about commercial use of BOTOX: ◦prevent wrinkles – maybe, BUT… ◦strasbismus: crossed eyes ◦blephorospasm: inability to keep eyelids open

Bacillus commonly found in soil produces ____________ Medically important species of Bacillus ____________________ : anthrax disease of cattle, sheep and humans Two forms of anthrax: ____________(skin): transmitted through a break in the skin cause pustule or lesions: tissue dies, crusts and falls off systemic (bloodstream): shock/ collapse ____________(pulmonary): transmitted by inhaling anthrax spores starts as pneumonia, high fever then septicemia, respiratory distress, death biowarfare agent: spores can be spread in aerosols no spread from person to person! penicillin effective if given early

Anthrax sepsis due to inhalation anthrax (now involving eye) Woman was exposed to animal hides; Pennsylvania 2006 Cutaneous anthrax – note BLACK lesions Inhalation anthrax on x-ray; Patient died next day.

Bacillus (cont’d) Bacillus ____________ : food poisoning often from starchy food especially rice Bacillus thuringiensis: insect pathogen produces delta endotoxin in crystal form insect eats toxin crystals and dies ◦sold for plant treatment as pesticide ◦transgenic plants engineered to produce toxin Bacillus subtilis: produces bacitracin Bacillus polymyxa: produce polymixin 1b.) Gram + rods --Bacillus

Mycobacterium __________________________________ __ Acid-fast stain – mycolic acid; Slow growing 1. Leprosy: mainly affects the skin, peripheral nerves, upper respiratory tract. ◦discovered by G.A. Hansen in 1873; first bacterium to be identified as causing disease in man. ◦contagious, but not widespread because 95% of the population have competent immune systems. 2. TB: causes tubercles in lungs, bones; poor health, crowding plays a role (communicable); ◦leading cause of death in the world from a single infectious disease! ◦ affects 1.7 billion people/year which is equal to one-third of the entire world population! 1b.) Gram + rods Mycobacterium

TB – cavitation, and calcified tubercle

Other pathogens 1. ___________________ - C. diphtheriae: causes diphtheria – DPT vaccine -pseudomembrane on tonsils -strong toxin – can destroy heart 2. ______________________– food poisoning; outbreak in hot dogs; intracellular pathogen 1b.) Gram + rods --others

Pallisades arrangement of Corynebacterium Can be pleiomorphic Pseudomembrane: necrosis, plasma, fibrin and bacteria

Nonpathogenic, but important! 1. Propionibacterium, Brevibacterium - swiss cheese, bacterial acne, stinky feet; propionic acid and sulfur compounds 2. Streptomyces - antibiotic production:  erythromycin, neomycin, streptomycin, tetracycline 3. ____________– normal flora in gut and vagina ◦found in yogurt, cheeses (mozzarella, cheddar, provolone)

____________ naturally lack a cell wall stabilized by sterols, resistant to lysis extremely small (0.1 – 0.5 µm) range in shape from filamentous to coccus or doughnut shaped ____________ ____________ Mycoplasma ____________ – atypical pneumonia in humans (“walking pneumonia”)