Bacteria

Proteobacteria

• named from mythical greek god, proteus, who could assume many shapes

• gram-negative

• chemoheterotrophic

• largest taxonomic group of bacteria

• five classes

Alphaproteobacteria

• gram-negative

• most capable of growing with very low nutrient levels

• some have stalks known as prosthecae

• human pathogens, obligate intracellular parasites, nitrogen fixing, plant pathogen, and nitrifying bacteria

Bartonella

• type of alphaproteobacteria

• cat-scratch disease

• human pathogen

Brucella: Brucellosis

• type of protebacteria

• human pathogen

• can evade immune system because they survive phagocytosis

Ehrlichia

• type of alphaproteobacteria

• obligate intracellular parasite

• Tickborne, ehrlichiosis (live in white blood cells)

Rickettsia

• type of alphaproteobacteria

• obligate intracellular parasite

• Arthropod-borne, spotted fevers

  • R. rickettsii: Rocky Mountain spotted fever

  
  

Azospirillum

• type of alphaproteobacteria

• nitrogen-fixing

• Grow in soil, use nutrients excreted by plants

Rhizobium

• type of alphaproteobacteria

• nitrogen-fixing

• Fix nitrogen in the roots of plants

Agrobacterium

• type of alphaproteobacteria

• plant pathogen

• inserts a plasmid into plant cells, inducing a tumor

Nitrobacter and Nitrosomonas

• type of alphaproteobacteria

• nitrifying bacteria

• Nitrosomonas oxidizes ammonium (NH4+) to nitrite (NO2-) which is oxidized by Nitrobacter to nitrate (NO3+) in a process called nitrification

Betaproteobacteria

gram negative

Burkholderia

• type of betaproteobacteria

• gram negative, motile rods

• pathogen: Burkholderia cepacia degrades more than 100 organic molecules.

• Is a common species that contaminates equipment in hospitals; causes infections in cystic fibrosis patients

Bordetella

• type of betaproteobacteria

• gram-negative, non-motile rods

• pathogen: B. pertussis - whooping cough (pertussis)

Neisseria

• type of betaproteobacteria

• gram-negative

• found in human mucous membrane

• pathogens: N. gonorrhea - gonorrhea & N. meningitidis - meningitis

Gamma Proteobacteria

• gram-negative

• contains the largest number of important bacteria

• subdivided into several orders.

• 1. THIOTRICHALES

  2. PSEUDOMONADALES

  3. LEGIONALLES

  4. VIBRIONALES

  5. ENTEROBACTERIALES

  6. PASTEURELLAS

  
  

Thiotrichales

• type of gammaprotetobacteria

• Francisella

• grows on complex media (blood or tissue extract)

• Francisella tularensis

  • Causes tularemia (rabbit fever)

  • Transmitted to humans with contact with small animals such as

  rabbits, cats, foxes etc.

  
  

Pseudomonadales

• types of gammaproteobacteria

• Pseudomonas and Acinetobacter

Pseudomonas (Pseudomonadales)

• gammaproteobacteria, pseudomonadales

• oppourtunistic pathogens and metabolically diverse

• polar flagella

• resistant to many antibiotics and disinfectants

• Causes pneumonia, urinary tract infections, infections in burns

Nosocomial infections – found in faucets, showers, syringes soaps,catheters & other hospital instruments

Acinetobacter (Pseudomonadales)

• gammaproteobacteria, pseudomonadales

• forms in pairs

• gains antibiotic resistance easily, some are resistant to all

• grows easily in hospital setting and once its there, its hard to get rid of.

Legionellales: Legionella

• causes legionellosis(Legionnaires’ Disease)

• caused by Legionella pneumophila: aerobic, gram-negative rod that grows in water and airconditioning; creates biofilsm and waterborn amebae

• Transmitted by inhaling aerosols; not transmitted person to person

• Symptoms: high fever and cough

• Treated with erythromycin and macrolides

The Vibrionales

vibiro, found in aquatic habitats

• V. cholerae causes cholera

• V. parahaemolyticus causes gastroenteritis (from raw shellfish)

• V. vulnificus causes septicemia and wound infections

Vibrio cholerae

• usually found in water contaminated with feces

• found naturally in water/shellfish

• about 5 million cases and 100k deaths (worldwide)

• symptoms include watery diarrhea and dehydration

Vibrio vulnificus and Vibrio parahaemolyticus

• found in brackish water worldwide

• highly concentrated in oysters and other shellfish

• Vibrio vulnificus wound infections: from contact with seawater, inflammation, necrosis, exotoxin secreted causes cellular damage

Vibrio food-borne infections

• mostly from eating raw oysters or shellfish

• rapid infection (24 hours)

• lesions on extremities, septic shock, organ failure from endotoxin

The Enterobacteriales

• commonly called the “enterics”

• gram-negative

• primarily inhabit the intestical tracts of animals and humans

• some are motile(flagella) and some have fimbriae for attachment to cell surfacs

• many produce bacteriocins - lyse other enterics

Escherichia (The Enterobacteriales)

• E. coli - most common facultative anaerobe in the gut

• gram-negative rod

• presence of this organism in food or water usually indicates fecal contamination (fecal indicator bacteria)

• pathogenic strains cause a variety of gastrointestinal diseases (urinary tract infections and Traveler’s diarrhea)

Salmonella (The Enterobacteriales)

• almost all are pathogenic

• common inhabitant of intestinal tract of animals (cattle and poultry)

• only 2 species, 2500+ serotypes(serovars)

• most common human pathogen = S. enterica serovar typhimurium (food poisoning due to uncooked poultry)

• S. enterica. serovar typhi - typhoid fever (most pathogenic)

  • Serious systemic infection can lead to intestinal wall perforation

Other Enterobacteriales

• Shigella – causes shigellosis (dysentery) , only found in humans

• Klebsiella – found in soil and water, can cause pneumonia

• Serratia – produces red pigment, found on catheters and in saline solutions. Causes UTI and RTI

• Yersinia – Causes plague, transmitted by prairie dogs

Pasteurellaes

• Pasteurella – pathogen of domestic animals, cows, dogs, cats, chickens

• Haemophilus – once thought to cause flu, actually causes meningitis, ear aches, arthritis, bronchitis

Deltaproteobacteria

• gram-negative

• Bdellovibrio - prey on other bacteria

Epsilon Proteobacteria

-organisms that are slender, gram-negative helical bacteria

1. Campylobacter

• Found in cattle & sheep

• May cause abortions in animals

• Campylobacter jejuni - gastroenteritis after ingesting improperly cooked meat and chicken (can survive at 43 C)

2. Helicobacter

• Helicobacter pylori – curved rod that causes gastritis and peptic ulcers in humans

• Multiple flagella

Nonproteobacteria (gram-negative)

1. CYANOBACTERIA

2. CHLAMYDIAE

3. BACTEROIDETES

4. SPIROCHAETES

5. DEINOCOCCUS/THERMUS

Cyanobacteria

• carry out oxygenic photosynthesis

• gas vesicles that provide buoyancy

• unicellular or filamentous

• nitrogen fixing occurs in heterocysts of filamentous cyanobacteria

Chlamydiae

• No peptidoglycan in the cell wall; grow intracellularly

• Chlamydia and Chlamydophila: Form an elementary body that is infective

• Chlamydia trachomatis causes trachoma and urethritis

• Chlamydophila psittaci causes respiratory psittacosis

• Chlamydophila pneumoniae causes a mild form of pneumonia prevalent in young adults

Bacteroidetes

Bacteroides

• Enteric (lives in gut)

• 1 billion per gram of feces

• Can cause infection if bowel is perforated

Spirochaetes

• coiled bacteria, motility by axial filaments

• good at moving through viscous fluids

• Treponema (causes syphilis)

• Borrelia (Lyme Disease)

• Leptospira (spread by water, urine of cats/dogs)

Deinococcus/Thermus

Deinococcus

• resistant to radiation: can survive radiation 1500x what is fatal to humans and was isolated from nuclear disasters like chernobyl

Thermus

• Thermus auaticus

• very heat stables, isolated from yellowstone hotspring

• where Taq polymerase comes from (PCR)

Gram-positive bacteria

• Firmicutes (low G + C ratios)

• Tenericutes (low G + C ratios)

• Actinobacteria (high G + C ratio

Tetanus (Lockjaw) - Fermicute

• caused by Clostridium tetani (gram-positive, endospore forming, obligate anaerobe)

• grows in deep wounds with anaerobic conditions

Tetanospasmin released from dead cells

• Enters CNS and blocks the relaxation pathway in muscles, causing muscle spasms

• Death occurs from spasms of respiratory muscles

• Fewer than 50 cases per year (Mortality of 25–50%)

• Prevented by vaccination with a tetanus toxoid (DTaP)

• Stimulates antibodies that neutralize the toxin, booster required every 10 years

Botulism - Fermicute

Caused by Clostridium botulinum (Gram-positive, endospore-forming, obligate anaerobe)

• Found in soil (vegetables), water

• Spores on vegetables --- canning = anaerobic ---germination (not on acidic foods like tomatoes)

• Intoxication comes from ingesting the botulinal exotoxin

• Specific for the synaptic end of the nerve; blocks release of the neurotransmitter acetylcholine causing flaccid paralysis

• Prevention: roper canning and use of nitrites to prevent endospore germination

Alternate infections of botulism

Infant botulism: C. botulinum growing in the intestines of infants

due to a lack of intestinal microbiota

• Does not compete with normal intestinal flora of adults

• If symptoms appear slowly: (crying, sucks poorly, can’t hold up head)

• If symptoms appear rapidly: (death due to respiratory failure)

• Associated with honey

Would botulism: growth of C. botulinum in wounds

• Treatment with respiratory assistance and antitoxins

Bacillales - Fermicute

• gram positive

• bacillus and staphylococcus

Bacillus - Fermicute

• Endospore–producing rods, facultative anaerobes, mainly found in soil

• Bacillus anthracis - causes anthrax.

• Disease of cattle that can be transmitted to humans

Staphylococcus - Fermicute

• gram-positive cocci that grow in grape-like clusters

S. Aureus - most important human pathogen

• grows as yellow/golden colony on agar plates

• can be found on skin and nasal passages

• can grow under high salt concentrations

• causes many skin infections and serious infections as well as nosocomial infections

• food poisoning, acne

• releases toxins (toxic shock syndrome)

• MRSA - Methicillin-resistant Staphylococcus aureus

Lactobacillales - fermicute

Lactobacillus, streptococcus, enterococcus

Lactobacillus - Lactobacillales

• gram positive

• in vaginal and oral cavity

• makes foods (yogurt, pickles, buttermilk, sauerkraut)

Streptococcus - Lactobacillales

• gram positive

• appears in chains

Streptococcal pharyngitis (strep throat)

• caused by group A streptococci (GAS) (streptococcus pyogenes)

• local inflammation, fever, tonsillitis, enlarged lymph nodes

Scarlet fever

• erythrogenic toxic produced by lysogenized S. pyogenes

Enterococcus - Lactobacillales

• gram positive

• found in human stool

• fecal indicator bacteria

• VRE - Vancomycin resistant Enterococcus

Tenericutes

Mycoplasma

• Do not have cell walls

• Highly pleomorphic because of no cell well (many shapes)

• Cell are small (5% of a bacillus)

Mycobacterium - Actinobacteria

• myco means fungus-like, (filamentous growth)

• Lipopolysaccharide layer is replaced with mycolic acid (causes Gram Stains to fail)

• M. tuberculosis Causes Tuberculosis

Tuberculosis - Actinobacteria

10 million develop TB annually; 2 million die

• ⅓ of the world's population has latent TB.

• Leading cause of death for those with HIV

BCG vaccine: live culture of avirulent M. bovis

• Not widely used in the United States due to questionable effectiveness

Diagnosis of Tuberculosis

Tuberculin skin test

• Positive reaction means a current or previous infection.

• T cells react with purified protein derivative from the TB bacterium.

• Delayed hypersensitivity induration

• Followed by an X-ray or CT exam to check for lung lesions

Treatment of Tuberculosis

• minimum of 6 months of drug therapy due to slow growth and dormancy

• first line drugs: isoniazid, rifampin, ethambutol, pyrazinamide

• Second-line drugs: aminoglycosides, fluoroquinolones, streptomycin, para-aminoslicyclic acid (PAS)

• Multi-drug-resistant (MDR) strains: resistant to first-line drugs

• Extensively drug-resistant (XDR) strains: resistant to second-line drugs

Corynebacterium diphtheriae - actinobacteria

• Causes diphtheria: forms a tough grayish membrane in the throat (fibrin and dead tissue) and blocks passage of air to the lungs

• Exotoxin produced by lysogenized bacteria: circulates in the blood; damages the heart and kidneys

• Prevented by DTaP vaccine (diphtheria toxoid)

Diphtheria - actinobacteria

Diphtheria membrane: Fibrin, tissue, bacterial cells (can lead to suffocation)

Propioibacterium - actinobacteria

P. acnes causes acne

Streptomyces

• One of most common soil bactera

• Produce a substance that gives fresh soil its musty odor

• Produces most of our commercial antibiotics