Flashcards in Gram Negative Bacteria Deck (82):
Describe the structure of a G- bacteria.
It has an inner membrane with proteins, a periplasm with lipoproteins and a peptidoglycan cell wall, and an outer membrane with proteins, LPS and porins
What are the four components of LPS from out to in?
1. O-antigen made of repeating sugars
2. Outer core with heptose, glucose, galactose
3. Inner core with heptose and KDO
4. Lipid A which confers virulence
Gram negative rods can be divided into two major groups. What are they?
Fermenters and non-fermenters
Are enterobacteriacae fermenters or non-fermenters? What strains of bacteria fall in this category?
They are gram negative rods that are fermenters.
Enterobacteriacae are vibrio and aeromonas
What bacteria are gram negative rod fermenters that are lactose fermenters? Which are fast and which are slow?
1. E. coli- fast
What are gram negative fermenters that cannot ferment lactose? (only other sugars)
Which gram negative rods are non-fermenters?
1. pseudomonas aeruginosa
What are examples of gram negative cocci that ferment maltose and glucose?
What are examples of gram negative cocci that do not ferment maltose, but can ferment glucose?
Gram negative cocci are all strongly ______ positive.
Gram negative coccobacillary _____________ oxidase positive.
What are examples of coccobacillary gram negatives?
1. Haemophilus influenza- cofactors
2. Bordatella pertussis- special media
3. moraxella catarrhalis
4. brucella abortus
5. pasteurella multocida
Lactose fermenting ____________ can be differentiated from non-lactose fermenting ________________.
Lactose= E. coli
Non-lactose = Salmonella
What agar would be used to isolate gram negative bacteria?
MacConkey's because crystal violet and bile restrict the growth of gram positives
What agar is used to isolate gram positives?
Colistin (nalidixic acid) because it binds LPS to inhibit growth of gram negatives
Describe the oxidase test.
It is used to see if a bacteria can produce cytochrome c oxidase (showing it uses an electron transport chain -- aerobic)
If something is oxidase positive, it will convert colorless solution to purple
1. gram stain and shape
2. oxygen usage
3. spore capability
4. catalase + or -
5. Fermentation ability
6. motility/type of flagella
1. Gram negative rod
2. facultative anaerobe
3. can NOT form spores
4. Catalase +
5. ferments glucose and others
6. motile with peritrichous flagella
What is the most common enterobacteriaceae?
Where is the reservoir for E. coli?
GI tract and they are commensal
What are the three most common syndromes associated with E. coli?
3. neonatal sepsis and meningitis
What is the number one cause of UTI?
What pili are associated with the attachment of E. coli?
1. Type 1 pillin
2. P fimbrae
For E. coli, certain ____ and _____ antigens correlate to disease
O (LPS) and K (capsular)
What antigen of E. coli is responsible for the vast majority of neonatal sepsis?
K1 capsular antigen
The KI capsular antigen of E. coli resembles the structure of ___________________________ because of the sailic acid.
group B streptcoccus capsule
What are the three major toxins associated with diarrheal syndromes of E. coli?
1. Heat-labile toxin (plasmid)
2. Heat-stable toxin (plasmid)
3. Shiga-like toxin (lysogenic prophage)
Describe the heat-labile toxin of E. coli. What does it cause?
It is an A-B toxin (like cholera) that activates adenylate cyclase.
It causes traveler's diarrhea
Describe the heat-stable toxin of E. coli What does it cause?
It is an AB toxin that activates guanylate cyclase and causes diarrhea
Describe the shiga-like toxin of E. coli.
What is the major example?
It is a lysogenic prophage that acts as an enterotoxin causing fluid secretion
Prime example: O157:H7
Describe Vibrio spp:
1. gram stain
2. motility (what kind of flagella)
1. They are curved gram negative rods
2. sIngle Polar flagella
What is the habitat of Vibrio spp?
(oceans, brackish water, eating shellfish, fecal-oral spread)
What are the three most notable kinds of vibrio spp?
1. Vibrio cholera
2. Vibrio parahaemolyticus
3. Vibrio vulinficus
What type of toxin is associated with vibrio cholera?
AB toxin that is a lysogenic prophage. It increases cAMP in the host causing secretory diarrhea (20L/day--> dehydration/death)
What serotypes of O antigen are associated with vibrio cholera?
O1 and O139
What disease is caused by vibrio parahaemolyticus?
gastroenteritis- cramping, abdominal pain, nausea, vomiting, fever, bloody diarrhea
What disease is associated with vibrio vulnificus? How do you acquire this infection?
1.Soft tissue infection and sepsis
2. liver disease
You get V. vulnificus from eating raw oysters
Describe Helicobacter pylori:
1. gram stain and shape
2. oxygen consumption
They are gram negative rods with a curved shape.
They are motile
What do helicobacter pylori utilize for energy?
they utilize a urease to break urea into ammonium and carbon dioxide
Where do helicobacter pylori reside?
In the stomach and duodenum
What disease do helicobacter pylori cause?
Peptic ulcers that can lead to:
MALT lymphoma (cured by antibiotics)
What is unique about the growth of C. jejuni and other campylobacter?
They grow best at 42 degrees celcius
Describe the shape, gram stain and motility of Campylobacter.
They are GNR that are curved and motile
What is the reservoir for campylobacter?
What bacteria contaminates most chickens in the US?
What disease presentation is associated with campylobacter?
Febrile, bloody diarrhea
Describe Pseudomonas aeruginosa:
1. gram stain and shape
3. oxygen consumption
2. motile with polar flagella
3. aerobic- (non-fermentor, oxidase +)
Pseudomonas aeroginosa is an aerobic GNR. This means that is will test ________ positive and will be a ______________.
It will test oxidase positive and will be a non-fermentor
What is unique about the growth of pseudomonas aeroginosa?
It has a fruity smell in culture and has pigments:
Pyocyanin and pyoverdin
What is the reservoir for pseudomonas aeruginosa?
Soil and water organisms (ubiquitous)
What virulence factor is associated with pseudomonas aeruginosa?
It can form biofilm
What diseases are associated with pseudomonas aeruginosa?
1. Nosocomial pneumonia associated with ventilators
2. Burn patients
3. cystic fibrosis
What is the gram stain and shape of pasteurella mutlocida?
It is a gram negative coccobacillary that is small and non-motile
What is the reservoir of pasteurella mutlocida?
It lives in the mouths of cats and dogs so it can cause infection after a bite
Describe the gram staining and shape of francisella?
GNR that is small and non-motile
What region of the country has francisella?
Tulare county in CA is where it was found, but it is now seen most in the midwest (oklahoma especially)
What disease is associated with francisella?
How is the infection acquired?
It is a zoonotic infection that causes "rabbit fever" and is acquired via puncture through skin or inhalation
What is the gram staining and oxygen consumption of legionella pneumophila?
It is a GNR that is aerobic and requires fastidious nutrition on culture
What is the reservoir for legionella?
It is ubiquitous in water and has adapted to parasitize free living amoeba
What specific cell is legionella an intracellular pathogen to?
Macrophages where they inhibit phagolysosomal fusion, acidification and respiratory burst
What disease is caused by legionella infection?
Community acquired pneumonia
1. gram staining
3. oxygen consumption
4. fastidious growth
1. GN cocci
3. aerobic- (oxidase +, non-fermentor)
4. requires excess CO2 to grow in lab
What agar would you use to grow Neisseria gonorrhea and Neisseria meningitidis?
Chocolate agar- blood agar that has been heated to release internal contents of RBC
Thayer-Martin from nonsterile sites
What is the reservoir of N. meningitidis?
nasopharynx of humans
What is the most common cause of sporadic bacterial meningitis in young adults (20-30)?
Where are epidemics of N. meningitidis likely to occur?
Highly crowded areas like dorms, prisons, military barracks
What is the main virulence factor of N. menigitidis?
It has a capsule to allow it to be antiphagocytic
How many serotypes does the N. meningitidis capsule have? What serotypes cause disease?
Which serotypes are there vaccines for?
There are 13 serotypes and A B C Y and W135 cause disease
There are vaccines for A C Y and W135 (NOT B)
What is the reservoir for N. gonorrhea?
humans- common STD
What are the 2 virulence factors associated with N. gonorrhea?
1. Pilin for attachment (with phase variation)
2. IgA protease to avoid immune detection
How do neisseria (both gonorrhea and meningitidis) avoid immune detection?
They have IgA protease
What is the most common presentation of N. gonorrhea?
1. Urethritis- drip/clap where there is milky white discharge and burning dysuria
2. prostatitis and orchitis in men
3. cervicictis and salpingitis (PID) in women
If gonorrhea disseminates beyond genitalia, what can it cause?
There are many other Neisseria besides gonorrhea and meningitidis.
They are all __________ positive
They differ in what four ways?
They are all oxidase positive
They differ in :
1. sugar use
2. growth in CO2
3. pigment production
4. capsular formation
What two enzymes do anaerobes lack that do not allow them to detoxify oxygen biproducts?
1. superoxide dismutase
Anaerobes are the predominant species in what four body regions?
2. GI tract
3. GU tract
4. Skin appendages (hair follicles and sweat glands)
Mouth flora is a mixture of _______ and ________/
viridans streptococci and anaerobes
Anaerobes comprise what percent of the colonic flora?
What diseases are caused by anaerobes in the mouth?
1. Peridontal disease
2. Oral and pharyngeal absess
3. Lung absess
What diseases are caused by anaerobes in the GI tract?
What diseases are caused by anaerobic bacteria in the GU tract?
Pelvic inflammatory disease and tubo-ovarian abscesses
What are the 5 main anaerobes that infect the head and neck?