Gram Negative Pathogens - Robison Flashcards
What constitutes the larges group of human pathogens?
Gram negative bacteria; usually cause disease and death in humans
Describe Neisseria
The only genus of Gram negative diplococci that regularly cause disease in humans
aerobic, catalase positive, oxidase positive
Cause gonorrhoeae and mengingitis
What are the virulent factors in neisseria gonorrhoeae?
pili because that is how it holds on to the cell
What was the past therapy for gonorrhea and why does it not work now?
Penicillin, but not it is resistant
Describe Neisseria meningitidis
Humans are the only carriers
Can be normal in microbiota
Transmitted through respiratory droplets and being in close contact
Dangerous!!!! Can die within 6 hours after intial symptoms
What are symptoms of meningitidis and meningococcal septiciemia? What are treatments?
Stiff Neck
Fever, headache, bright lights,
Blood coagulation
treatments are vaccines, penicillin, or cephalosporins
What are virulent factors of N. meningitidis?
capsule and endotoxin
Describe Enterobacteriaeae
gram negative, faculatively aerobic rods, ferment, catalase positive, oxidase negative
Usually killed by disinfectants
What are the three types of enterobacteriaceae surface antigens?
O- parts of lipopolysaccharides
K- capsule (Kapsule - german)
H- flagella
What are the three groups of enterobacteriaceae?
Coliforms- ferments lactose, part of the normal microbiota and may be opportunistic
Non coliforms opportunists- do not ferment lactose
Frank pathogens- do not ferment lactose
What is the most common and important coliforms? And what are characteristics
E. coli
UTIs and gastroenteritis are the most common E.coli diseases
Many different varieties
What is a type 3 secretion?
Protein complex that acts like a syringe
Usually in a strain of pathogenic E. coli
Causes diarrhea, hemorrhagic colitis, and HUS
Describe shigella
gram negative and non motile
parasite of GI tract
produces diarrhea inducing enterotoxin
causes shigellosis (dysentery)
How is shigella spread?
flies, fingers, fomites, food, feces
What is the mech of shiga toxin?
AB toxin
inactivates ribosomes- aka no more protein synthesis
Which two organisms can invade a host cell?
Listeria and Shigella
Describe salmonella
Gram negative, motile, bacilli
Enterobacteria
Found in intestines and feces of most birds, reptiles and mammals
People usually infected by consumption of contaminated foods
What does samonella enterica serovar Typhi cause?
Typhoid fever
Humans are the only hosts
Usually infected through food and affects the gallbladder and liver
“Typhoid Mary” - most infamous carrier; cook
Treated with vaccines and antimicrobial drugs
What does Klebsiella cause?
pneumoniae
Enterobacteria
produces a capsule that protects from phagocytosis
What is Yersinia?
normal pathogen of animals with 3 important species
Enterobacteria
Y. enterocolitica causes symptoms of appendicitis
Y. pseudotuberculosis causes less severe intestinal inflammation
Y. pestis causes bubonic plague!
Describing bordetella
small aerobic gram negative non motile coccobacillus
causes whooping cough
inhaled in aerosols and grow on epithelial cells
Describe pseudomondads
Gram negative aerobic bacilli
Usually in plants and wter
opportunistic bacteria
Problematic in hospitals
What is a common infector of severe burns?
Pseudomonas aeruginosa
difficult to treat with antibiotics
Describe francisella tularensis
non motile, strictly aerobic, gram negative
TINY ORGANISM
causes tularemia
Spread to humans through bite of tick or deerfly
usually misdiagnosed because it is similar to other diseases
