Alpha Proteobacteria A presentation by Alicia Agnew, Joe Bianco, Geraldine Petica, Corine Schuster, and Alexandria Metijevic

Alpha-Proteobacteria: A Pathogenic Approach

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

Alpha-Proteobacteria Lifestyles Obligate intracellular ◦ Ex: Rickettsia Facultative intracellular ◦ Ex: Brucella Extracellular pathogens ◦ Ex: Agrobacterium Symbionts of plant and animals ◦ Ex: Sinorhizobium

How do Pathogenic 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

Steps for Pathogen Survival 1. Find a host 2. Attach to the host and colonize 3. Invade and evade the host making the host immune suppressed 4. Be able to survive outside the host

How the Body Stops the 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. microscope-thumb jpg

So Remember To: Wash your hands before touching your face or eating Take your Vitamin C and L-Lysine supplements to boost your defense against pathogens.

Some Examples of α proteobacteria  Order: Rhodospirillales  Genus: Azospirillum  Order: Rickettsiales  Genus: Rickettsia  Genus: Wolbachia  Order: Caulobacterales  Genus: Caulobacter  Order: Rhizobiales  Genus : Hyphomicrobium  Genus: Rhizobium  Genus: Agrobacterium

Rickettsia 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.

Ehrlichia 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.

Bartonella 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

Brucella 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 flu Brucellosis may lead to chronic symptoms

α lpha Proteobacteria Mechanisms used by α proteobacteria to infect host organisms

Alpha Proteobacteria and their Modes of Infection There are many different orders and genera of α proteobacteria Many 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 Azospirillum A 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 Rickettsia Rickettsia enter the host cell by inducing phagocytosis They 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 Caulobacter and Hyphomicrobium  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 Rhizobium Infect the roots of leguminous plants (ex: beans, peas, or clovers) Nodules form where this bacteria is present There 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 Agrobacterium  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 Wolbachia The live only inside the cells of their hosts, usually insects Have an endosymbiotic relationship with their hosts

Alphaproteobacteria: Mode of Transmission There are many different Alphaproteobacteria, and thus many different modes to transfer them.

Epidemic Typhus We 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 Typhus This 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 Typhus This 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

Rickettsialpox This 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 Fever This 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-Proteobacteria 2

Infections should be treated with Antibiotics Doxycycline is preferred mg/daily for at least one week 2,3 Rifampin can be used in pregnant women

Doxycycline- An Introduction Member of tetracyclines First isolated from Streptomyces species in late 1940s Broad spectrum antibiotics, works on: ◦ Gram negative ◦ Gram positive ◦ Ricksettae ◦ Mycobacterium ◦ protozoa

Doxycyline Unlike other tetracylclines, does not have OH at C6  greater stability and penetration of membranes 4

Mechanism of Action against Bacteria Inhibits both 70s and 80s of prokaryotes and eukaryotes, but has greater affinity for 70s 4,5 reversibly bind to 30s of 70s at the A site preventing the attachment of tRNA 4,5 Are thus bacteriostatic

Bibliography 1. “Alpha-proteobacteria”. Files/AlphaProteobacteria.htm Files/AlphaProteobacteria.htm 2. Petri, William MD PHD. “Treatment”. November November “Viral and Rickettsial Zoonoses Branch: Human Ehrlichiosis in the United States”. Center for Disease Control and Prevention. nt.htm. April 5, nt.htm. 4. Thomas, Sheena. “Doxycyline” Buck, Marcia FCCP. “Doxycycline”. Sitemaker.umich.edu/mc2/doxycycline. November 4, 2003.