Microbiology 251- Test 2 (Ch 4/5)

What are some ways bacteria are useful in the environment?

-Nitrogen fixation (converts Nitrogen to Ammonia)
-Carbon fixation (Converts CO2 into usable carbon)
-Degradation of toxic compounds

Characteristics of Rhizobium

-Nitrogen-fixing
- Live in roots of legume plants
- Produce ammonia (use by plants)

In what type of symbiotic relationship do both organisms benefit?

Mutualism

In what type of symbiotic relationship is one organism harmed and the other is unaffected?

Amensalism

In what type of symbiotic relationship does one organism benefit and the other is unaffected?

Commensalism

In what type of symbiotic relationship are both organisms unaffected?

Neutralism

In what type of symbiotic relationship does one organism benefit while the other is harmed?

Parasitism

What is hemolysis?

Destruction of red blood cells (Alpha-partial, Beta-total, Gamma-None)

Characteristics of Mycobacterium tuberculosis

-Mycolic acid coat (waxy)
-Difficult to treat w/ antibiotics
-Slow growth
-Sx: cough(sputum/blood clumps), fever, crackling in lungs,

Characteristics of Mycobacterium leprae

-Causes leprosy (Hansen's disease)
-Found in peripheral body regions (cooler areas)

List some qualities of the human microbiome

-All microbes associated to the human body
-Ratio ~10:1
-Bacteria thrive in damp/moist areas (mouth, nose, throat, ears, vagina, GI)
-Some bacteria thrive on dry places as well
-Can be resident or transient microbes

Why is maintenance of the human microbiome so important?

-Important roles in digestion(GI tract), immune function, and overall homeostasis

How are blood agar plates used?

-TSA agar with 15% sheep blood added, looking for "clear zone" where RBCs were lysed
-Common in clinical settings
-Streptococcus (pneumoniae/pyogenes) and Staphylococcus (aureus) are common examples

Characteristics of Corynebacterium

-Gram positive
-Pairs of rods (v-shaped)
-Facultative anaerobes
-Found in skin and mucous membranes
-Harmless unless toxin-producing

Characteristics of Corynebacterium dihptheriae

- Causes diptheria (respiratory tract)
- Produces hramful toxin

Characteristics of Clostridium

-Obligate anaerobes
-Gram-positive rods
-Endospore formers
-Produce toxins

Characteristics of Clostridium botulinum

- Causes food poisoning
- Produces botulinum toxin
- Endospores found in soil
- Can't give honey to infants bc of underdeveloped immune system (potential colonization in GI tract after spore ingestion)

Characteristics of Clostridium perfringens

-Causes myonecrosis (gas gangrene) and food poisoning
_Obligate anaerobe
-Wound infections (aerobic environment) can be treated w/ hyperbaric chamber

Characteristics of Clostridium tetani

-Causes tetanus
-Produces toxin (tetanosasmin)
-Found in soil, and deep wounds

Characteristics of Clostridium difficile

-Severe colitis (some severe cases are deadly)
-Common hospital acquired infection ("C-diff")

Characteristics of Streptococcus

-Obligate fermenters (produce lactic acid)
- Grow in chains/pairs
-Gram positive
- Can cause RBCs to lyse
- Some are pathogenic

Characteristics of Streptococcus pyogenes

-All pathogenic (on a "range" of severity)
-Beta-hemolytic group A streptococci
- Can be in some human normal flora of respiratory tract (<15%)
- Common cause of strep throat (bacterial pharyngitis)
- Some skin infections (impetigo)
- Rare: necrotizing faciitis

Characteristics of Streptococcus pneumoniae

-Gram positive cocci in pairs
-Causes bacterial pneumonia, menengitis, and endocarditis (mostly immunocompromised pop.)
-Virulent strands have capsule

Characteristics of Lactobacillus

-Gram positive rods
-Most are aerotolerant anaerobes (not killed by O2)
-Fermentative (produces lactic acid)
-Part of normal microbiota and vagina (helps maintain acidic environment)
-Antibiotics can disrupt growth, causing secondary infection (yeast infection)

Characteristics of Bacillus

-Gram positive rods
-Forms endospores
-Obligate aerobes/facultative anaerobes
-Source of antibiotics (found in soil)
-Opportunistic pathogen (food poisoning, anthrax, etc.)

Characteristics of Bacillus cereus

-Common in soil
-Found in milk
-Can cause food poisoning

Characteristics of Bacillus anthracis

-Causes anthrax
-Uncommon in environment, hard to isolate
-Affects animals
-In humans: black ulcers, severe enterocolitis, and bran damage from swelling
-Fatal when untreated

Characteristics of Staphylococcus aureus

-Cocci in clusters, not chains
-Causes: skin infections that produce boils, carbuncles, cellulitis, or impetigo
-Some produce enterotoxin (enteritis, staph food poisoning, toxic shock syndrome)
-Many antibiotic resistant strains (MRSA, VRSA) which are contagious and extremely difficult to treat
-Threat in hospitals, nursing homes, etc.

Characteristics of Staphylococcus epidermis

-Main habitat is human skin; nonpathogenic for normal pop.
-Important cause of infections associated w/ IV caths
-Problematic in hospital settings (lots of immunocompromised pts)

Characteristics of Pseudomonas

-Unique gram negative bacteria (produces pigments)
-Aerobic
-Does NOT ferment
-Found widespread in soil/water
-Can grow practically ANYWHERE in the body, cause of many infections (opportunistic pathogen)
-Biofilm can cause chronic, difficult to eradicate infections

Characteristics of Vibrio

-Gram negative rods, often curved (commas)
-Found mostly in aquatic environments (more alkaline), some food

Characteristics of Vibrio cholerae

-O1 or O139 can produce toxin responsible for cholera (widespread epidemics)
-Transmission: ingestion of contaminated water (or food, mostly seafood)
-Hypersecretion of electrolytes/water in colon, profuse watery diarrhea and dehydtration
-Uncommon in US

Characteristics of Legionella pneumophila

-Aquatic environment (warm water)
-Often reside in protozoa
-Causes respiratory disease (only transmits from environment to human, not human to human)
_Ex: contaminated air conditioning units
-Hard to culture; needs "charcoal" media

Characteristics of Escherichia coli

-Most strains are mutualistic w/ humans (E. coli in gut)
-Used as indicator for fecal contamination
-Can produce potent shiga toxin which inhibits protein synthesis and causes hemorrhagic colitis, inflammation of GI tract, and bloody diarrhea
-Hemolytic uremic syndrome (HUS) in severe cases
-O157 and H7 can infect ground beef/produce

Characteristics of Salmonella

-Many species
-Identify using antisera
-Cause of typhoid fever

Describe protists

-algae and protozoa
-highly diverse in organism and environment

Fungal cell walls characteristically contain:

Chitin

Fungal cell membranes characteristically contain:

Ergosterol

What are the most common growth characteristics of fungi?

-Moist environment
-Slightly acidic
-Can grow with/without light
-Vary in O2 requirement

How many major groups of fungi are there?

7

What fungi groups contain pathogens? (4

-Zygomycota
-Ascomycota
-Basidiomycota
Microsporidia

How are fungi commonly grouped?

Based on their reproductive strategies

Do fungi photosynthesize or have chlorophyll?

No and No

How do fungi obtain food?

Heterotrophs- obtain carbon through complex organic compounds

What type of fungi is used known as baker's yeast?

Saccharomyces cerevisiae

Penicillin is isolated from:

Penicillium mold

What are mycoses?

Illness caused by fungi

Multicellular fungi are usually called:

Molds

Molds are made of filaments called:

Hyphae

What are septate hyphae?

Hyphae with cell walls

What are coenocytic hyphae?

Hyphae with no cell walls b/w cells

What are tangled networks of hyphae?

Mycelium

Unicellular fungi are commonly known as:

Yeasts

How do yeasts reproduce?

Budding (asexual)

What is a dimorphic fungi?

Can appear as yeast or mold, often changing to adapt to environment

Characteristics of Aspergillus

-Produces aflatoxins
-Contaminant of nuts/grains

Characteristics of Dermatophytes

-Genera that causes athlete's foot, jock itch, ringworm

Characteristics of Histoplasma capsulatum

-Respiratory pathogen
-Associated with birds and bats

Characteristics of Coccidioides immitis

-Valley fever

Characteristics of Candida albicans

-Common cause of yeast infection (vagina and other moist body sites)

Characteristics of Cryptococcus neoformans

-Causes serious lung infections (especially in immunocompromised pts)
-Basidocarp (forms spores through budding in fruiting bodies)

Characteristics of Microsporidia

-Unicellular fungi
-Obligate intracellular parasites
-Entry via a polar tube

Common fungi used as foods:

-Edible mushrooms
-Morels
-Truffles

Characteristics of Naigleria fowleri

-"Brain eating" amoeba

Characteristics of Acanthamoeba

-Causes amoebic keratitis (eye infection)

Characteristics of Entamoeba histolytica

-Parasitic amoeba, causes amebic dysentery

Characteristics ofPlasmodium

-Causes Malaria (Amoebazoa)
-Complex lifecycle involving mosquito

Characteristics ofToxoplasma gondii

-Causes toxoplasmosis
-Amoebazoa transmitted via cat feces or undercooked meat

Characteristics of Giardia

-Parasitic protozoa (forms resting stage/cyst)
-GI infections/diarrhea
-Transmitted through feces/contaminated water

Basic features of fungi

-Lack chlorophyll
-Do not photosynthesize
-Heterotrophic