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C. trachomatis is a human pathogen that causes trachoma , a disease of the eyes, often leading to blindness. C. trachomatis also causes the sexually transmitted disease lymphogranuloma venereum (LGV). This disease is often mildly symptomatic, manifesting as regional lymph node swelling, or it may be asymptomatic, but it is extremely contagious and is common on college campuses.

[link] summarizes the characteristics of important genera of Alphaproteobacteria.

A diagram showing the life cycle of Chlamydia. An epithelial cell is infected by small spheres labeldd elementary bodies. Within 12 hours, these form into reticulate bodies which divide  to form inclusions within 24 hours. Within the inclusions more elementary bodies are formed and within 72 hours these are released when the cell ruptures.
Chlamydia begins infection of a host when the metabolically inactive elementary bodies enter an epithelial cell. Once inside the host cell, the elementary bodies turn into active reticulate bodies. The reticulate bodies multiply and release more elementary bodies when the cell dies after the Chlamydia uses all of the host cell’s ATP. (credit: modification of work by Centers for Disease Control and Prevention)
Class Alphaproteobacteria
Genus Microscopic Morphology Unique Characteristics
Agrobacterium Gram-negative bacillus Plant pathogen; one species, A. tumefaciens , causes tumors in plants
Bartonella Gram-negative, pleomorphic, flagellated coccobacillus Facultative intracellular bacteria, transmitted by lice and fleas, cause trench fever and cat scratch disease in humans
Brucella Gram-negative, small, flagellated coccobacillus Facultative intracellular bacteria, transmitted by contaminated milk from infected cows, cause brucellosis in cattle and humans
Caulobacter Gram-negative bacillus Used in studies on cellular adaptation and differentiation because of its peculiar life cycle (during cell division, forms “swarm” cells and “stalked” cells)
Chlamydia Gram-negative, coccoid or ovoid bacterium Obligatory intracellular bacteria; some cause chlamydia, trachoma, and pneumonia
Coxiella Small, gram-negative bacillus Obligatory intracellular bacteria; cause Q fever; potential for use as biological weapon
Ehrlichia Very small, gram-negative, coccoid or ovoid bacteria Obligatory intracellular bacteria; can be transported from cell to cell; transmitted by ticks; cause ehrlichiosis (destruction of white blood cells and inflammation) in humans and dogs
Hyphomicrobium Gram-negative bacilli; grows from a stalk Similar to Caulobacter
Methylocystis Gram-negative, coccoid or short bacilli Nitrogen-fixing aerobic bacteria
Rhizobium Gram-negative, rectangular bacilli with rounded ends forming clusters Nitrogen-fixing bacteria that live in soil and form symbiotic relationship with roots of legumes (e.g., clover, alfalfa, and beans)
Rickettsia Gram-negative, highly pleomorphic bacteria (may be cocci, rods, or threads) Obligate intracellular bacteria; transmitted by ticks; may cause Rocky Mountain spotted fever and typhus
  • What characteristic do all Alphaproteobacteria share?

Betaproteobacteria

Unlike Alphaproteobacteria, which survive on a minimal amount of nutrients, the class Betaproteobacteria are eutroph s (or copiotrophs), meaning that they require a copious amount of organic nutrients. Betaproteobacteria often grow between aerobic and anaerobic areas (e.g., in mammalian intestines). Some genera include species that are human pathogens, able to cause severe, sometimes life-threatening disease. The genus Neisseria , for example, includes the bacteria N. gonorrhoeae, the causative agent of the STI gonorrhea , and N. meningitides , the causative agent of bacterial meningitis .

Questions & Answers

how does Neisseria cause meningitis
Nyibol Reply
what is microbiologist
Muhammad Reply
what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
Ntefuni Reply
What is microbiology
Mercy Reply
studies of microbes
Louisiaste
when we takee the specimen which lumbar,spin,
Ziyad Reply
How bacteria create energy to survive?
Muhamad Reply
Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
Louisiaste
what is sporadic nd endemic, epidemic
Aminu Reply
the significance of food webs for disease transmission
Abreham
food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
Mark
explain assimilatory nitrate reduction
Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
Shu Reply
Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
Mark
what is cell
faisal Reply
cell is the smallest unit of life
Fauziya
cell is the smallest unit of life
Akanni
ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
Musa
what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
_Adnan
define infection ,prevention and control
Innocent
I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
Lubega
Heyy Lubega hussein where are u from?
_Adnan
en français
Adama
which site have a normal flora
ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
Safaa
skin
Asiina
skin,Oral,Nasal,GIt
Sadik
How can Commensal can Bacteria change into pathogen?
Sadik
How can Commensal Bacteria change into pathogen?
Sadik
all
Tesfaye
by fussion
Asiina
what are the advantages of normal Flora to the host
Micheal
what are the ways of control and prevention of nosocomial infection in the hospital
Micheal
what is inflammation
Shelly Reply
part of a tissue or an organ being wounded or bruised.
Wilfred
what term is used to name and classify microorganisms?
Micheal Reply
Binomial nomenclature
adeolu

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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