Final; Small Gram-Negative Pathogens Flashcards
This is an obligate intracellular pathogen growing only inside cells or on live tissues and depend on their host for ATP
Chlamydiae
What are the 4 recognized species of Chlamydiae
C. trachomatis
C. pneumoniae
C. psittaci
C. pecorum
Chlamydiae is the leading cause of preventable what and the most common what
blindless
agents of sexually transmitted bacteria infections
How is Chlamydiae spread
droplet or direct infection
4 F’s; fingers, flies, fomites, fornication
Where does Chlamydiae infect
mucosal epithelial cells
localized; eyes, lungs, genitalia
What are the symptoms of a Chlamydiae genital tract infection
males; prostitis, epididymitis
femalse; cervicitis, PID, premature birthda, pelvic pain, newborn infection
both; urethritis, infertility, proctitis, arthritis
How is the disease manifested in females
usually asymptomatic in females; chronic or repeat infections can cause sterility and/or ectopic pregnancy
What is characteristic of Chlamydiae infections
may be acute or chronic; silent period
asymptomatic carriage results in most damage and scarring
during birth, infants can contract the infection
This is the non-replicating infectious particle that enters epithelial cells and is internalized by receptor-mediated endocytosis
elementary body
The elementary body modifies the endocytic vesicle in which two ways
maintain pH above 6.2
prevents vesicle from fusion with lysosomes
How is the vesicle modified by the host
modified with host glycolipids for camouflage
What do the infectious EBs change into
larger intracellular active organisms called reticular bodies
What do reticular bodies do within the vesicle
synthesize molecules using host metabolites and energy
divide by binary fission
organisms develop slowly (2-3 days per cycle)
How do reticular bodies uptake nutrients
tube-like structures that allow them to feed on eukaryotic host cell without leaving the inclusion vacuole
18-23 tubes
This is inflammation of the conjunctiva, can cause blindness and scarring of the cornea
trachoma (C. trachomitis)
How is trachoma spread
by direct contact with yes, nose, and throat secretions from affected individuals or contact with objects such as towels or washcloths
This is a STD, systemic invasive infection apparent in the lymph nodes that drain the genital tract found in developing countries
lymphogranuloma venerum
This is the most prevalent chlamydial pathogen in the human population; 50% of people up to age 20% are infected and 80% of older adults
chlamydophila pneumoniae
C. pneumoniae invokes what type of symptoms
asymptomatic or acute respiratory response but chronic respiratory infections have been associated with asthma, CF, and lunch cancer
directly observed in 40-100% of patients with atherosclerotic heart lesions
What is the treatment for chlamydia
target the metabolically active RBs
there are four membrane laters to penetrate
organisms grow slow so the antibiotics must be taken for a longer period of time
This is an obligate intracellular small gram-negative rod bacterium that can be spread from animals to humans (zoonoses)
rickettsiae
What is the main difference between rickettsiae and chlamydia
rickettsiae can synthesize its own ATP and is capable of independent metabolism
it may lack certain metabolites necessary for growth
no flagella or endospores
must be cultivated in animals, embryonated eggs, or cell cultures in the lab
What are some diseases caused by rickettsiae
rocky mountain spotted fever
typhus
How is rickettsiae transmitted
only ticks are naturally infected
the ticks feed on large mammals and the larva/nymph feed on small rodents
the bacteria is spread through the blood stream
How does rickettsiae spread and multiply
attaches to vascular endothelial cells; induces endocytosis
once inside, presumably lyse the phagosome (phospholipase) and enter the cytosol
How does R. prowazekii exit the cell
lysis
How does R. ricketttsii exit the cell
gets extruded from the cell through local projections (filopodia)
actin helps to give it a push
How does R. tsutsugamushi exit the cell
by budding through the cell membrane; will remain enveloped as it infects other cells
What is the injury to the host as a result of Rickettsiae
it is proportional to the number of intracellular bacteria
lysis of cells leads to rash; hemorrhagic spots
it can travel to other vessels including heart and brain
75% of patients will clear before antimicrobial treatment
This causes typhus fever, recrudescent typhus, and is transmitted by human lice
the reservoir is humans and flying squirrels
R. prowazekii
This is prevalent and widespread, marine typhus, and is transmitted by rats and rat fleas
R. typhii
This causes scrub typhus, there is a variety of antigenic types but there is no rash as observed in the other
Orentia tsutsugamushi
This is an obligate intracellular bacteria discovered in 1987 that infects mostly monocytes, macrophages, and neutrophils
Ehrlichia
What are the disease/infections of ehrlichia
human granulocytic ehrlichiosis
human monocytic ehrlichiosis
causes fevers, malaise, headache, and myalgia
Where does ehrlichia develop within the cells
within host cell vacuoles first as reticulate cells (RC) and then as dense-core cells (DC)
Why is diagnosing rickettsiae problematic
during the fist visit patients may not be aware of tick bite or have a fever/rash
required eukaryotic cell cultures or inoculation of animals
handling is hazardous
What are the clinical diagnosis tests for rickettsiae
antibody titer
fluorescent antibody assay
complement fixation
latex agglutination
This is the smallest organism capable of growth on cell-free media, its cells membranes contain sterols and is found in
mycoplasma
What are some important characteristics of mycoplasma
*requires sterol characteristic "friend egg" appearance small colonies slow growth lack of cell wall; not sensitive to penicillin
What are the four species of mycoplasma that causes disease
M. pneumoniae M. genitalium M. hominis Ureaplasma urealyticum some microplasms are part of microbiota
Where is M. pneumonia encountered
humans are the only reservoir
spread through close contact via respiratory droplets; mild to moderately contagious
is adheres to respiratory epithelium
M. pneumoniae is typicaly referred to as what
“walking pneumonia” primary atypical pneumonia; not cleared by penicillin
Where does M. pneumonia infect
colliery function of the lungs is impaired
it is largely limited to the respiratory mucosa that lines the airways
doesn’t get into lung alveoli; bronchopneumonia
tissue toxin substances may include H2O2
What are the main cells of the inflammatory response
lymphocytes
What type of damage can M. pneumonia cause besides in the respiratory tract
hemolytic anemia; IgM = cold hemagglutinins, colder temps cause them to aggregate encephalitis erythema multiforme (rash)
This is the newest emerging human pathogen causing urethritis, cervicitis, endometritis, and PID
M. genitalium
These are frequently associated with diseases in newborns, commonly found in respiratory and genitourinary tract; and is present in most of the sexually active population
M. hominis and U. urealyticum
True or False
M. hominis and U. urealyticum can be isolated from the spinal fluid of newborns, but always cause disease
False; it doesn’t always cause disease
