Gram negative pathogens (complete) Flashcards
What are the Gram-negative pathogens we study
- Neisseria species
- Escherichia Coli
- Shigella species
- Salmonella species
- Klebsiella pneumoniae
- Yersina species
- Bordetella pertussis
- Pseudomonas aeruginosa
- Francisella tularenesis
- Legionella pneumophila
What group is the largest group of human pathogens and why
Gram-negative bacteria, in part because of the Lipid A in their cell wall
What does Lipid A trigger in humans
Fever, vasodilation, inflammation, shock, and disseminated intravascular coagulation (blood clots in blood vessels)
What are the three things that any gram-negative bacteria needs to cause disease or death in humans
- breach the skin or mucus membranes
- grow at 37 degrees celcius
- evade the immune system
What is the only Gram-negative Cocci that regularly causes diseases in humans
Neisseria
What do Neisseria usually look like
gram-negative diplococci, in pairs, with flattened sides
are neisseria aerobic or anaerobic
aerobic
What are the two pathogenic types of neisseria
neisseria gonorrhea
neisseria meningitidis
neisseria are pyogenic, or pyrogenic
pyogenic (pus creating)
What is the isolation media used for neisseria
chocolate agar, + increased CO2
What is the major virulence factor of neisseria gonorrhea
the attachment pili
what is the most common reportable disease is the US
gonorrhea
What happens to males with gonorrhea
infection of the anterior urethra = acute inflammation
pus discharge and painful urination
can cause rectal or pharyngeal infections also
What happens to females with gonorrhea
infection of vaginal-cervical junction
80% of infections are asymptomatic
may cause salpingitis
may spread to lower abdomen and cause Pelvic Inflammatory Disease (PID)
What is salpingitis
a gonorrhea infection of the fallopain tubes (20% sterility rate)
What happens to children with gonorrhea
as they pass through the birth canal they can contrat gonococcal opthalmia neonarum (eye infection)
What is done to prevent gonococcal opthalmia neonarum
antibiotic ointments placed in the eyes of newborns
What is neisseria gonorrhea transmitted
sexual contact
which age group has the highest incidence of neisseria gonorrhea
20-24
How is gonorrhea diagnosed
by the symptoms, and observation of the organisms in the pus
What is the treatment for gonorrhea
used to be penicillin, but not it has 50% resistance
now it is cephalosporin + tetracycline
how is gonorrhea prevented
controlling sexual behavior
Where can you find neisseria meningitidis
only in humans (normal microbiota of the upper respiratory tract)
What is the problem with neisseria meningitidis
when the bacteria gets in the blood or cerebrospinal fluid it becomes life threatening meningitis
neisseria meningitidis is the most common cause of meningitis in individuals _____
under 20
How is neisseria meningitidis transmitted
how How
respiratory droplets among people living in close contact (dorms and barracks)
What are the two diseases associated with neisseria meningitidis
meningococcal meningitis
meningococcal septicemia
how quickly can meningococcal meningitis go from initial symptoms to death
6 hours
what is meningococcal septicemia
blood poisoning by neisseria meningitidis. produces blood coagulation and the formation of minute hemorrhagic lesions.
What are the two virulence factors of neisseria meningitidis
the capsule and the endotoxin
how is neisseria meningitidis transmitted
aerosol droplets, close contact facilitates transmission
carrier rate is higher in military personnel
How is neisseria meningitidis diagnosed
symptoms, characteristics
How is neisseria meningitidis treated
i.v. penicillin or cephalosporin
What should high risk populations for neisseria meningitidis do
get the quadrivalent vaccine
What are enterobacteriaceae
a large family of gram-negative rods
What kinds of interaction do enterobacteriaceae have with oxygen
facultative aerobic
are enterobacteriaceae common commensals in humans
yes
what are the three types of surface antigens on enterobacteriaceae
O, K, and H
are enterobacteriaceae infections common nosocomial infections
yes
how well do disinfectants and antibiotics work against enterobacteriaceae
disinfectants easily kill them, antibiotics do not
What are the three types of enterobacteriaceae
- coliforms - those that ferment glucose
- noncoliforms - those that don’t ferment glucose
- Frank pathogens
What does the presence of coliforms in water indicative of
impure water, and poor sewage treatment
What is the most common and important of the enterobacteriaceae coliforms
Escherichia Coli (E. Coli)
What are the most common diseases associated with E. Coli
UTIs and Gastroenteritis
What is the most common cause of non-nocosomial UTIs
E. Coli
What are the two main virulence factors of E. Coli
pili and exotoxins
What are the 5 main different varieties of E.Coli
Uropathic E. Coli - more likely to produce UTI
Enterotoxogenic E. Coli - causes diarrhea
Enteropathogenic E. Coli - infant diarrhea
Enterohemorrhagic E. Coli - Hemolytic Uremic Syndrome
Enteroinvasive E. Coli - causes dysentary
Why is type 1 pili of E. Coli important
those E. Coli with type 1 Pili can hold on to the bladder and aren’t flushed out, so they can cause a UTI. Those without it are flushed out and not pathogenic
what causes most E. Coli Epidemics
undercooked ground beef, unpasteurized milk or juice, or fresh vegetables
What is shigella
a gram-negative nonmotile bacteria that is a parasite of the human digestive system
what is the diseases associated with shigella, and what causes it
the disease is a bacillary dysentary called shigellosis, the diarrhea inducing enterotoxin is what causes it
shigella is spread by the 5 Fs, what are they
flies fingers fomites food feces
What is the shigella toxin similar to, and how
it is similar to the ricin toxin, it is similar because it is an AB toxin, it inactivates ribosomes, and causes apoptosis
What happens with shigella once it enters the cell
it is absorbed into a phagosome, which it escapes, then polymerizes actin into a tail and flies around the cell and into others
What does salmonella do once absorbed into marcophages
it multiplies in them and spreads
Where is salmonella found
in the intestines and feces of most birds, reptiles and mammals
What is the most common cause of salmonella infections for humans
food contaminated with animal feces
What are the two important pathogens of salmonella
Salmonella enterica serovar typhimurium
Salmonella enterica serovar typhi
what does Salmonella enterica serovar typhimurium cause
salmonellosis
what does Salmonella enterica serovar typhi cause
typhoid fever
Where can you find Salmonella enterica serovar typhi
only in humans
how do you get Salmonella enterica serovar typhi
ingestion of food or water that is in from sewage contaminated with the bacteria
What happens with Salmonella enterica serovar typhi once you ingest it
it goes from the intestines into the blood, to the liver, spleen, bone marrow, and gall bladder, then back into the intestines and all over again. can cause peritonitis
Who was typhoid mary
a cook with Salmonella enterica serovar typhi, that accidentally killed many families by feeding them contaminated food
How is typhoid fever treated
with antimicrobial drugs
how is typhoid fever prevented
temporary vaccines can be given to those traveling to areas where typhoid fever is endemic
how does salmonella get through the intestinal walls
it causes the M-cells to ruffle so it can go through
What is klebsiella
an opportunist with a capsule that protects it from phagocytosis
what is the most common pathogenic type of klebsiella
Klebsiella pneumoniaea
What does Klebsiella pneumoniaea cause
pneumonia, and maybe bacteremia, meningitis, wound infections, and UTIs
What is Yersina
a normal pathogen of animals that can be acquired via consumption of food or water contaminated with animal feces
What are the three important yersina species
Yersina enterolitica
Yersina pseudotuberculosis
Yersina pestis
What is caused by a Yersina entericolitica infection
inflammation of the intestinal tract (similar symptoms to appendicitis)
What is caused by Yersina Pseudotuberculosis
less severe inflammation of the intestinal tract than Yersina entericolitica
What is caused by Yersina Pestis
the bubonic plague
high fever, swollen painful lymph nodes (buboes)
pneumonic plague
How quickly does a respiratory infection of yersina pestis kill
2-4 days from exposure to death.
how quickly after symptoms begin does treatment have to be started to prevent death
treatment must be started within 24 hours of symptoms onset or fatality is near 100%
What are the virulence factors of yersina pestis
F1 capsule - antiphagocytotic
T3SS - delivers YOPS
YOPS - inhibit cytokines, destroy cytoskeleton, trigger apoptosis
What is bordetella
a small aerobic nonmotile coccobacillus
What is the most significant bordetella
bordetella pertussis
what does bordetella pertussis cause
pertussis ((whooping cough))
Who is most commonly infected with bordetella
children
what are the virulence factors of B. pertussis
Adhesons
Toxins
How is B. pertussis transmitted
inhaled in aerosols
What are the two pertussis adhesons
filamentous hemagluttinin and perussis toxin
What are the four B. Pertussis toxins
pertussis toxin
Adenylate cyclase toxin
dermonecrotic toxin
Tracheal cytotoxin
what does pertussis toxin cause
increased mucus production
what does adenylate cyclase toxin cause
increased mucus production and inhibition of leukocyte functions
what does dermonecrotic toxin cause
constriction and hemorrhage of blood vessels
what does tracheal cytotoxin cause
inhibits cilia movement and kills ciliated cells
Where can pseudonomads be found
water and plants
why are pseudonomads problematic in hospitals
because they can be found in numerous locations
what is the most common human pseudonomad pathogen
psuedomonas aeruginosa
Who is typically infected with pseudomonas aeruginosa
immunocompromised patients
What condition is often worsened by pseunomonas aeruginosa
cystic fibrosis, it increases the likelyhood of death in these patients
what does pseudomonas aeruginosa do to protect itself from phagocytes
forms a biofilm
What else is pseudomonas aeruginosa involved in
infections of severe burns
hot tubitis
What are some diagnostic characteristics of pseudomonas aeruginosa
pyocyanin - a blue-green pigment with a fruity odor
fluorescent pigment
how easily is pseudomonas aeruginosa treated
not easily, it is resistant to many antibacterial drugs
What is francisella tularensis
nonmotile strict aerobe found in animals, that causes tularemia
how is francisella tularensis trasmitted to humans
bite of an infected tick or deerfly, or contact with an infected animal
how infectious is francisella tularensis
very, less than 10 cells needed, and it can spread through unbroken skin and mucus membranes
Why is tularemia often misdiagnosed
its symptoms are common to other bacterial and viral diseases
What is different about the necessary conditions of legionella pneumophilia
it needs cysteine, iron and a lower pH (6.9) to grow
how do humans become infected with legionella pneumophilia
inhaling the bacteria in aerosols from various water sources
legionella are intracellular parasites
that is true
What causes legionaires disease (causes pneumonia)
legionella pneumophilia
how do you eliminate the legionella pneumophilia
you can’t, but you can reduce their numbers to successfully control it
what kind of agar is legionella pneumophilia grown on
charcoal agar
how and where does legionalla pneumophilia multiply in humans
it multiplies in macrophages
- it gets phagocytosed (OMP and Mip assist)
- the phagosome is coated in ribosomes and mitochondria (don’t let the phagosome fuse)
- legionella multiplies inside the macrophage to very high numbers, then the release a pore forming toxin and lyse the cell, then spread.
