Alpha ProteobacteriaAlpha ProteobacteriaA presentation by Alicia Agnew, Joe Bianco, Geraldine Petica, Corine Schuster, and Alexandria Metijevic

Alpha-Proteobacteria:Alpha-Proteobacteria:A Pathogenic Approach A Pathogenic Approach

What is a pathogen?What is a pathogen?An agent of disease or a disease

producer.A pathogen generally refers to

infectious organisms.Different pathogens include:

◦Bacterial pathogens◦Viral pathogens◦Fungi pathogens

What is Pathogenic Bacteria What is Pathogenic Bacteria Bacteria is made up of one

cell.◦ Although they are made up

of one cell they are capable of multiplying and dividing by themselves.

There are 3 main bacterial shapes.◦ Coccus◦ Spiral◦ Rod

Some bacteria is pathogenic◦ Pathogenic bacteria produce

toxins to harm their host.http://www.bacteriamuseum.org/niches/pbacteria/

pathogenicity.shtml

Figure 1: A Gram stain of Clostridium botulinum. This picture was taken under the magnification of a microscope.

http://www.dmacc.cc.ia.us/instructors/scottie.htm

Alpha-Proteobacteria Alpha-Proteobacteria LifestylesLifestylesObligate intracellular

◦Ex: RickettsiaFacultative intracellular

◦Ex: BrucellaExtracellular pathogens

◦Ex: AgrobacteriumSymbionts of plant and animals

◦Ex: Sinorhizobiumhttp://www.pnas.org/content/99/20/12503.full?ck=nck

How do Pathogenic How do Pathogenic Organisms Spread?Organisms Spread?Through transmission the infectious

organism moves to a healthy host.Organisms are spread through direct

and indirect methods:◦ Direct methods such as directly touching a

telephone that an infected person has touched.

◦ Indirect methods such as a bite from an infected mosquito.

Air borne transmission ◦ Generally enters the body via the

respiratory tract. Such as Mycobacterium tuberculosis

http://www.truthaboutwellness.com/pathogen.html

Steps for Pathogen Steps for Pathogen SurvivalSurvival1. Find a host2. Attach to the host and colonize3. Invade and evade the host

making the host immune suppressed

4. Be able to survive outside the host

How the Body Stops the How the Body Stops the Spread of Disease Spread of Disease With the production of

L-lysine and Vitamin C which are natural inhibitors against:◦ Collagen digesting

enzymes found on viruses and pathogens.

Humans cannot produce their own Vitamin C so these inhibitors are needed as inhibitors.

http://topouest.com/wp-content/uploads/2009/01/germs-under-the-microscope-thumb3131800.jpg

So Remember To:So Remember To:Wash your hands before touching

your face or eatingTake your Vitamin C and L-Lysine

supplements to boost your defense against pathogens.

http://www.truthaboutwellness.com/pathogen.html

Some Examples of Some Examples of αα proteobacteria proteobacteria Order: Rhodospirillales

Genus: Azospirillum Order: Rickettsiales

Genus: Rickettsia Genus: Wolbachia

Order: Caulobacterales Genus: Caulobacter

Order: Rhizobiales Genus : Hyphomicrobium Genus: Rhizobium Genus: Agrobacterium

RickettsiaRickettsia

Gram negative rod shaped bacteria or coccobacilli.

Transmitted to humans by bites from insects and ticks.

Cause diseases known as the Spotted Fever Group◦ Epidemic Typhus◦ Endemic Murine Typhus◦ Rocky Mountain Spotted Fever

In humans rickettsial infections damage the permeability of blood capillaries, which results in a characteristic spotted rash.

EhrlichiaEhrlichia

Gram negative, rickettsialike bacteria that must live in white blood cells

Ehrlichia species are transmitted by ticks to humans and cause ehrlichiosis, which can sometimes be fatal.

Symptoms generally include fever, headache, fatigue, and muscle aches. They begin to appear after an incubation period of 5-10 days.

Many individuals who become infected do not become ill or they develop only mild symptoms.

Blood tests indicate low white blood cell count, and elevated liver enzymes.

BartonellaBartonella

The best known human pathogen is Bartonella henselae, which causes cat-scratch disease.

Small red bump appears and in 2-3 weeks swells

Cat-scratch disease can be more serious for an immunocompromised person

BrucellaBrucella

All species of Brucella are obligate parasites of mammals and cause brucellosis

Cause disease in humans when they come in contact with animals or animal products contaminated with this bacteria

Symptoms are similar to the fluBrucellosis may lead to chronic

symptoms

ααlpha Proteobacterialpha ProteobacteriaMechanisms used by α proteobacteria to infect host organisms

Alpha Proteobacteria and Alpha Proteobacteria and their Modes of Infectiontheir Modes of InfectionThere are many different orders

and genera of α proteobacteriaMany of them infect different types

of host organisms, from plants to animals to humans

There are numerous different mechanisms of infection

They exhibit a variety of different types of relationships with their hosts

Infection Mechanism of Infection Mechanism of AzospirillumAzospirillumA soil bacterium that grows in

close association with roots of plants; can be isolated from plant root systems

It uses the nutrients that the plants excrete

In return, it fixes nitrogen from the atmosphere

Infection Mechanism of Infection Mechanism of RickettsiaRickettsiaRickettsia enter the host cell by

inducing phagocytosisThey quickly enter the cytoplasm

of the cell; once there, they reproduce by binary fission

Another type of rickettsialike bacteria, ehrlichiae, live obligately within white blood cells

Infection Mechanism of Infection Mechanism of CaulobacterCaulobacter and and HyphomicrobiumHyphomicrobium These can be found in

low-nutrient aquatic environments, such as lakes

They use stalks to anchor their organs to surfaces

They take up nutrients through these stalks

If they anchor to the surface of a living host, the bacteria use the host’s excretions as nutrients

Figure 11.2 Caulobacter. Most of the Caulobacter in this photo are in the stalked stage.

Infection Mechanism of Infection Mechanism of RhizobiumRhizobiumInfect the roots of leguminous

plants (ex: beans, peas, or clovers) Nodules form where this bacteria

is presentThere is a symbiotic relationship

between the bacteria and the plant, resulting in fixation of nitrogen from the air for use by the plant

Infection Mechanism of Infection Mechanism of AgrobacteriumAgrobacterium Invade plants, but do

not lead to nodule formation, and do not fix nitrogen

A specific Agrobacterium, Agrobacterium tumefaciens, causes a disease called crown gall

A. tumefaciens inserts a plasmid into the plants chromosomal DNA

This plasmid contains the genetic information of the bacteria

Crown gall

University of Georgia Plant Pathology Archive, University of Georgia, Bugwood.org

Infection Mechanism of Infection Mechanism of WolbachiaWolbachiaThe live only inside the cells of

their hosts, usually insectsHave an endosymbiotic

relationship with their hosts

Alphaproteobacteria: Alphaproteobacteria: Mode of TransmissionMode of TransmissionThere are many different Alphaproteobacteria, and thus many different modes to transfer them.

Epidemic TyphusEpidemic TyphusWe find that this disease affects

humans and is transmitted by lice. The disease itself is caused by Rickettsia prowazekii , which the lice are carrying. It is uncommon in the United States, but does occur among homeless individuals.

Murine TyphusMurine TyphusThis disease is transmitted by

fleas that carry the organism Rickettsia typhi. The fleas travel on mice, cat and oppossums. It is seen throughout the world.

Scrub TyphusScrub TyphusThis disease is transmitted by

mites and mite larvae and is caused by the microorganism Rickettsia tsutsugamushi . It is typical to Asiatic areas and is generally carried by rodents

RickettsialpoxRickettsialpoxThis disease is transmitted by

mites and chiggers and is caused by the organism, Rickettsia akari. This disease is also constantly on the move by rodents that carry the infectious organisms. It was originally observed in New York city and then later Russia, Korea and Africa.

Q FeverQ FeverThis disease is caused by the

microorganism Coxiella burnetii and infection can occur when inhaling the organism or through drinking raw milk. It is transported through sheep, cattle and goats and is common throughout the world.

Alpha-ProteobacteriaAlpha-Proteobacteria

2

Infections should be treated Infections should be treated with Antibioticswith AntibioticsDoxycycline is preferred2

100 mg/daily for at least one week2,3

Rifampin can be used in pregnant women

Doxycycline- An Doxycycline- An IntroductionIntroductionMember of tetracyclinesFirst isolated from Streptomyces

species in late 1940sBroad spectrum antibiotics, works

on:◦Gram negative◦Gram positive◦Ricksettae◦Mycobacterium◦protozoa

DoxycylineDoxycylineUnlike other tetracylclines, does

not have OH at C6 greater stability and penetration of membranes4

Mechanism of Action against Mechanism of Action against BacteriaBacteriaInhibits both 70s and 80s of

prokaryotes and eukaryotes, but has greater affinity for 70s4,5

reversibly bind to 30s of 70s at the A site preventing the attachment of tRNA4,5

Are thus bacteriostatic

BibliographyBibliography 1. “Alpha-proteobacteria”.

http://www.life.umd.edu/classroom/bsci424/BSCI223WebSiteFiles/AlphaProteobacteria.htm

2. Petri, William MD PHD. “Treatment”. http://www.merck.com/mmhe/sec17/ch195/ch195a.html. November 2007.

3. “Viral and Rickettsial Zoonoses Branch: Human Ehrlichiosis in the United States”. Center for Disease Control and Prevention. http://www.cdc.gov/ncidod/dvrd/ehrlichia/Treatment/Treatment.htm. April 5, 2000.

4. Thomas, Sheena. “Doxycyline”. http://sitemaker.umich.edu/mc10/doxycycline.

5. Buck, Marcia FCCP. “Doxycycline”. Sitemaker.umich.edu/mc2/doxycycline. November 4, 2003.