Gram Positive Bacteria (Chapter 4, Exam 2)

Bacteria with gram positive cell walls

Firmicutes and Actinobacteria

Firmicutes (endospore forming)

gram positive

endospore forming bacteria that can remain viable for years

resist dying, freezing, and chemical disinfectants

genera: Clostridium and bacillus

lactic acid bacteria

low Guanine and Cytosine content

Bacillus

spore forming genus

B. thuringinesis

B. anthracis

B. cereus

B. thuringiensis

producer of insecticide compounds

block digestive track since they are toxic

B. anthracis

anthrax

transmitted to humans

form of bioterrorism

B.cereus

food poisoning

from starchy foods like rice

Clostridium

obligate anaerobes

produce endospores, anaerobic habitats like soil and aquatic sediments rich in organic nutrients

growing endospore swells the end of the cell, giving a clip. shape

C. tetani

C. botulinum

C. perfringens

C. difficile

C. tetani

tetanus

from soil, rusty nails

inhibits relaxation pathways

produce neurotoxin-->enters neurons--> moves around in CNS and causes static paralysis

C. botulinum

botulism

produce toxin that blocks acetycholine

caused flaccid paralysis

can cosmetically erase wrinkles

C. perfringens

gas gangrene

gets in wounds and causes necrosis in tissue

C. difficile

severe colitis and diarahhea

often after the normal gut microbiota

eradicated by antibiotics

Firmicutes (non-endospore forming)

gram positive

grow at low temperatures

lactic acid bacteria like lactococcus and lactobacillus

ferment milk to make yogurt and cheese

Listeria species

Listeria spp

intracellular pathogens causing diseases affecting GI tract and nervous system

Congenital Listeria Monocytogenes

results in premature delivery, miscarriage, or stillbirth

can cross placenta

Gram positive cocci of Firmicutes (Non-endospore formers)

enterococcus

streptococcus (chains)

staphylococcus (Grape-like clusters--S. aureus)

Streptococcus

spherical cells in chains

gram positive

produce enzymes that damage tissue

aerotolerant, fermentat sugar, lack ETC

found in oral cavity, skin, intestines

demineralize--> cause tooth decay

Two groups of Streptococci

S. pyogenes

S. mutans (viridans)

S. pyogenes

strep throat

S. mutans

dental caries

Beta hemolysis on blood agar

complete hemolysis

zone of clearing (no green color)

S. pyogenes

S. agalactiae

S. algalactiae

neonatal sepsis and meningitis

Alpha hemolysis on blood agar

partial hemolysis (green)

s. pneumoniae

S. mutans

greenish zone of clearing

Enterococcus

gram positive

genus of fecal origin, can be pathogenic

found in intestinal tract; hospital contaminants

E. faecalis and E. faecium

E. faecalis and E. faecium

infect surgical wounds and the urinary tract through catheters

VRE

vancomycin resistant enterococcus

Staphylococcus

grape-like clusters of cocci

facultative anaerobe

tolerate drying and high salt conc

-high osmotic pressure, so can survive in high salt environments

-found in nasal secretions

common commensals and parasites of humans and animals that occasionally cause serious infections

S. epidermis and S. aureus

S. aureus

causes wound infections

antibiotic resistant

produces enterotoxin

MRSA, skin skalded syndrome

can cause food poisoning

S.epidermis

lives on skin and mucous membranes; endocarditis, bacteremia, UTI

Mycoplasma

bacteria lacking a cell wall

parasitize multicellular organisms

pleomorphic

maybe the smallest-self replicating organisms capable of a free-living organisms

live within animal and plant hosts

small genomes

M. pneuominae

Low guanine and cytosine

Firmicutes

High guanine and cytosine

Actinobacteria

Actinobacteria

high G+C gram positive bacteria

distinctive feature: presence of several different peptidoglycan in cell wall

A. israelli, S. coelicolor

highly pleomorphic, some branching filaments (branching bacteria)

common inhabitant in soil

Actinomyces israelii

forms branched mycelial filaments

endocarditis-inflammation of the inner lining of heart

Streptomyces

most important genus of antibiotic producers

reproductive asexual spores formed at the ends of aerial filaments

-if each spore lands on a suitable substrate, can germinate into a new colony

Streptomyces coelicolor

forms branched mycelial filaments

produces many antibiotics

Actinomycetes

form mycelia with branching filaments

important in soil ecology and some species are human pathogens

Frankia

nitrogen fixing bacteria

form symbiotic relationship with alder trees to do nitrogen fixation

Nocardia

Form fragmenting filaments; acid-fast

N. asteroides causes pulmonary infections

resembles mycobacteria

Actinobacteria (that are not actinomycetes)

-cell walls contain mycolic acid and cells stain acid-fast

-dont form mycelia

-pathogens and symbionts

--> Gardnerella vaginalis, Corynebacterium diptheriae, proprionibacterium freudreichii, Cutibacterium

-bacilli and cocci

Gardnerella vaginalis

bacterial vaginosis

plemorphic, gram variable, doesn't stain well

Corynebacterium diphtheriae

Diphtheria toxin

diagnostic

white/grayish membrane forms in throat and blocks air to reach lungs

prevented using DTaP vaccination

Cutibacterium acnes

Gram-positive bacilli/rods

found on skin

acne

producing propanoic acid

Key genus of Actinobacteria

Mycobacterium

common in soils and and most are harmless

contains several human pathogens

-Acid fast (AFB), mycelia acids

Mycobacterium tuberculosis, Mycobacterium leprae

Mycobacterium tuberculosis

causes tuberculosis

use skin test for exposure

vaccine not prevalent in U.S since it interferes with skin test

Deinoccocus radiodurans

high G +C, gram positive bacteria

more resistant to radiation than endospores

unique arrangement of DNA that facilitates rapid repair of radiation damage

red/pink color due to carotenoids

Theramus aquaticus

found in hot springs in Yellowstone national park

source of Taq polymerase

Taq polymerase

thermotolerant enzyme used in polymerase chain reaction (PTC)