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112 Cards in this Set

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Pseudomonas aeruginosa
non-lactose fermenting Gram negative rod, oxidase positive

shiny, blue-green pigment on blood agar, but shows a lack of lactose fermentation on MacConkey

sweet “grape-like” odor

uncommon in immune competent

one of the most common in hosp patients and is a frequent cause of pneumonias, urinary infections, and bloodstream infections
age-related changes in the pathogens responsible for pulmonary exacerbations in pts with cystic fibrosis
infants and younger children, S. aureus and H.influenzae

older children and adolescents, P. aeruginosa

Later stages of disease are often associated with pulmonary infections due to multiple-drug resistant P. aeruginosa, other resistant grams negatives
Antibiotics active against P. aeruginosa
piperacillin, 3rd and 4th gen cephalosporins, carbepenems, certain floroquinolones (like ciprofloxacin), and aminoglycosides (especially tobramycin)
L. monocytogenes
facultative anaerobic Gram positive bacillus

one of the leading causes of community-acquired meningitis in adults older than 60 years of age and infants younger than 1 month; less frequently in pregnant women and immunocompromised hosts
most common clinical manifestation of Listeriosis
mild disease characterized by fever, nausea, vomiting, and diarrhea

associated with epidemic gastroenteritis
where can L. monocytogenes be found? (what should pregnant women avoid eating during their third trimester?)
soft cheeses, processed delicatessen meats, and raw vegetables
How do children get L. monocytogenes
vertical transmission from mother to child during or after childbirth is likely responsible for neonatal infections
Initial therapy for bacterial meningitis in a 67 year old woman
steroids, vancomycin (for penicillin resistant S. pneumoniae), cetriaxone (3rd gen cephalosporin, covers S. pneumoniae & N. meningitidis), and ampicillin (for Listeria monocytogenes)
Treatment for patient with confirmed L. monocytogenes meningitis
ampicillin with gentamicin for synergy
mortality rate due to L. monocytogenes meningitis
high: approximately 30%
What strain of Haemophilus is associated with invasive dz in children? What is the typing done by?
Type B, a polysaccharide capsule

Hib
Why are infants 6 months to 3 yrs susceptible to Hib? How are they protected the first 6 months?
Lack antibodies to b capsule.

mother passes antibodies via breast milk
What are the 4 things that Hib causes in infant 6 months to 3 yrs?
Meningitis
Acute epiglottitis
Septic arthritis
Sepsis
What are some acid fast bacteria?
mycobacteria

mycobacterium tuberculosis
mycobacterium leprae
What are some bacteria without cell walls?
Mycoplasma
Where do the vast majority of bacteria in our body live?
large intestine
What are the four sterile places in the body?
blood, urine, brain, and lungs
Pathogen
microbe capable of producing damage
Virulence
relative ability of a microbe to cause damage/disease in a host
Damage f(host) with examples

Class 1
Class 2
Class 5
Class 1- dz in immune-compromised, beneficial in normals
(candida, staph epiderm)

Class 2- dz in immune-compromised, but no benefit (pneumococcus, cryptococcus)

Class 5-dz in those w/strong immune response (H1N1, SARS)
Serratia
gram negative rod

bright red pigment

causes UTIs, wound infections, pneumonia in nosocomial infections
What is the virulence factor in Candidiasis? (defies Koch's postulate)
medical therapy(impaired barrier)/impaired host is virulence factor

normal component of human flora
What is the virulence factor in Legionellosis? (defies Koch's postulate)
envt is virulence factor

true host is amoeba, transmitted via water sources
How does mononucleosis defy Koch's postulate?
Epstein Barr Virus

causes three diseases

mononucleosis, B-cell tumor, Burkitt's lymphoma
How do ulcers defy Koch's postulate?
H. pylori causes two dieases, one of which is non-infectious

ulcers and stomach cancer
Defns
Sporadic
Endemic
Epidemic
Pandemic
Sporadic- isolated

Endemic-regionally

Epidemic-anywhere, tends to affect large #s of ppl

Pandemic-global
What microbes have the capacity to survive outside its host? What microbes dont have this ability?
Fungi can survive outside host

Viruses cannot
What kind of nucleus, ribosomes, and outer surface do fungi have?
Eukaryotic (have mitochondria)

80S (60S + 40S)

Chitin
What kind of nucleus, ribosomes, and outer surface do bacteria have?
Prokaryotic

70S (50S + 30S)

Peptidoglycan
Aerobic
Anaerobic
Facultative
Microaerophilic
Aerobic- need oxygen

Anaerobic- don't need oxygen

Facultative- indifferent to oxygen

Microaerophilic-enhanced growth with oxygen
What causes pneumonia in alcoholics?
Klebsiella (aspiration pneumonia)
What features are unique to gram positive organisms?
teichoic acid

Cell wall
What features are unique to gram negative organisms?
Endotoxin/LPS (lipid A)

Periplasmic space
Siderophores
take up and transport iron to microbe
What does a inducer do?
binds to (inactivates) repressor

turns on transcription
What strategies does N. gonorrhea use to avoid detection?
antigenic variation- make new pilin subunits

phase variation-entire protein or truncated protein via a slipped strand mispairing
How does yersinia avoid host cell immune response?
YopB/D form pores allowing...

YopH to enter which has tyrosine phosphatase activity which interferes with host cell immune response
Aminoglycosides (kanamycin, gentamicin) mechanism?
bind to 30s subunit to prevent binding to 50s subunit
B-lactams (penicillin and amoxicillin) mechanism?
inhibit synthesis of peptidoglycan
What strategy does Salmonella typhi use to survive in host?
cadC gene

activates lysine decarboxylase to catalyze the reaction from lysine--> cadaverine

cadaverine= greater tolerance t low pH
What strategies does Pseudomonas aeruginosa use to survive in host?
acquisition of iron

quorom sensing- way bacteria communicate with one another; colonize only when a certain # of bacteria in an area
What organism causes syphillis?
Treponema pallidum
How does campylobacter jejuni acoid detection?
has sialyl transferase which is involved in glycosylation (unusual to find in bacteria); sialic acid is on RBCs
What is the most effective strategy for controlling a toxin-mediated disease?
Immunization against Toxin A subunit (b/c it is the active subunit, most directly involved with causing damage)
AB Toxins

How many A? B? for....

Diptheria toxin?
Cholera?
Anthrax?
Diptheria toxin? A + B

Cholera? A + 5B

Anthrax? 2A + B
What are bacterial viruses called?
phage
Which toxins are stable to boiling?

Which toxins are inactivated by boiling?
endotoxins are stable to boiling.

most exotoxins are inactivated by boiling
Cornyebacterium diptheriae and immunized ppl
gram positive, non-spore forming rod

inactive toxin used for vaccine

ppl can be colonized but not affected since immunized against toxin, not the bacteria
Mechanism of action of Cornyebacterium diptheriae toxin?
inactivates E2F protein which is involved in elongation step of translation
Where does Cornyebacterium diptheriae colonize and what does it form?
colonizes the pharynx and

forms a pseudomembrane
What does Cornyebacterium diptheriae cause?
damages heart and neural cells by interfering with protein synthesis (E2F) with its exotoxin rockets
Classification of Cornyebacterium diptheriae and Listeria moncytogenes
gram positive rods
Classification of Bacillus (anthracis) and Clostridium (botulinum, tetani)
gram positive, spore-forming rods
Three bacteria most responsible for causing most meningitis by baby coming out

Later?
Listeria monocytogenes, Group B strep, E. Coli

Later: N. meningitidis. H. influenzae
What are two disease that we are vaccinated against the toxin but not the microbe?
Tetanus (Clostridium tetani)

diptheria (Cornyebacterium diptheriae)
How does one get Clostridium tetani?
skin trauma by any object contaminated with spores

germinate in necrotic tissue (anaerobic) and release tetanospasmin
Vibrio cholera

what is cholera?

how does it cause death?
curved gram negative rod with single polar flagellum

diarrheal disease that causes rice water diarrhea

Cholera causes death by dehydration
How does Vibrio cholera cause disease?
bacteria attach to epithelial cell, release choleragen toxin....

choleragen has one A subunit and 5 B subunits, B binds to intestinal epithelial cell and A enters causing secretion of NaCl and prevention of NaCl reabsorption
What three things does Clostridium perfringens cause?
Gas gangrene

1. Cellutis/wound infection

2. Clostridial myonecrosis: fatal, if left untreated

3. Watery diarrhea
What three microbes release Shiga toxin/Shiga-like toxin?

What do these toxins do?
Shigella
Enterohemorrhagic E. Coli
Enteroinvasive E. Coli

inhibit 60s ribosome resulting in intestinal epithelial cell death, bloody diarrhea
What two microbes release heat labile toxin and cholera toxin?

What do these toxins do?
Enterotoxigenic E. Coli and vibrio cholera

inhibit the absorption of NaCl, watery diarrhea
What causes Hemolytic Uremic syndrome?
What are the symptoms?
Enterohemorrhagic E.Coli 0157:H7

anemia, thrombocytopenia, renal failure
Why are infants susceptible to botulism spores in honey but adults are not?
Infants have STERILE GI tract

In adults, commensal bacteria outcompete botulism spores and is the reason when they don't get infected when eating honey
What is the most virulent staph specie?
S. aureus
What is the main reservoir for S. aureus?
nasal mucosa
When staph epidermidis causes disease, what is the most likely cause?
presence of foreign body; catheter or prosthetic device
Important facts abt staph aureus
resistant to penicillin

propensity to invade the vascular system

s. aureus bacteremia is a common complication of IVs
How do supeantigens work?
bind to MHC-II receptors of monocytes-macrophages at sites distinct from classic binding groove,causin exuberant non-specific immunologic activation and release of cytokines
Penicillin binding proteins
crosslink peptidoglycan chains in bacterial cell walls

altered PBPs will grant resistance to penicillin
Beta-lactamASE
used by bacteria to destroy the beta-lactam ring of penicillin
What strategies does MRSA use that make it so hard to kill?
B-lactamase AND altered PBPs
What is the difference between CA-MRSA and hospital acquired MRSA?
CA-MRSA is generally susceptible to a range of non-beta lactam antibiotics, but....

hospital acquired MRSA is generally broadly resistant...

REMEMBER both MRSA types have B-lactamase AND altered PBPs
Clinical presentation of CA-MRSA
severe skin abscesses
necrotizing pneumonia
necrotizing fasciitis
septic arthritis
bacteremia
What is Panton-Valentine leukocidin (PVL)?
crucial mediator of increase virulence in CA-MRSA

toxin that acts by damaging neutrophils causing neutrophil apoptosis and by triggering interleukin and inflammatory mediator production
What people have higher rates of infection for staph aureus?
3Ds

diabetics, dialysis, drugs
what increases cAMP?
Cholera, Anthrax, Monetezuma's (Enterotoxigenic E. Coli), Pertussis
What is the microbe best at setting up distant sites of infection?
Staph aureus

endocarditis, osteomyelitis
Toxins produced by Staph Aureus and diseases they can cause
TSST-1, enterotoxin, epidermolytic toxin, membrane damaging toxin (leukocidin)

Toxic shock- multisystem
Food poisoning- projectile vomiting
Scalded skin syndrome- will heal w/o scarring
What does TSST-1 induce the release of?
IL1, IL2, TNF
How do superantigens work?
binds to Antigen presenting cells and presents to T-cells in a nonspecific way
-->1 in 5 Tcells are activated and host hurts itself thru a non-specific exuberant immune reaction
Weird presentations of staph aureus
Job's syndrome- neutrophil dysfunction, abscesses on skin

Botryomycosis- chronic granulomas that do damge over months to yrs
What will S. epidermidis have?

so what?
altered PBPs

dont give B-lactams like penicillin, give vancomycin
What features distinguish enterococci (group D strep) from other strep?
ability to grow in bile
What features distinguish enterococcus faecalis (enterococcal group D strep) from non-enterococcal group D strep?
enterococcus faecalis (enterococcal group D strep) can grow in NaCl, it is one of the hardiest orgs and part of normal GI flora

both grow in bile
Group A Strep
aka?

ID

Symptoms
aka? Strep pyogenes

ID? B-hemolysis, Bacitracin susceptible

Symptoms? Mom, my throat hurts, my skin is disintegrating, and my body is turning scarlet!!!"

Later...Mom, I want to watch Rheumatic Fever! Mom, my urine is tea colored!!!!
What is the virulence factor in Group A Strep that is anti-phagocytic and can be used for typing strains?
M protein
What microbiological feature of enterococci (Group D strep) distinguish it from other strep?
ability to grow in bile
Group B strep (strep agalactiae)
B for baby!!! B-hemolytic, CAMP positive

early onset: neonatal meningitis, pneumonia, sepsis

prophylaxis helps in preventing early onset dz, but not late onset
Viridans strep
Viridans = Verde =green a-hemolytic

Dental infections
Endocarditis

Eating heart valves slowly
Group D strep (Enterococci)
normal GI flora, gamma hemolytic

able to grow in high salt and bile

nosocomial pathogen

UTI, bacteremia, endocarditis, wound infection
Red currant jelly sputum with bulging fissure sign. what bacteria? what ppl? what is it?
Klebsiella, diabetics and alcoholics

lobar pneumonia
What type of pts is pseudomonas prevalent in?
immune compromised pts
Cystic fibrosis pts
nosocomial infections
probs with treating pseudomonas
highly resistant so need to treat with extended spectrum beta lactams
Proteus
"swarming"
has urease which causes stone formation, results in high urine pH
Serratia
SerREDtia

Red color

hospital outbreaks
Klebsiella vs. Pseudomonas
both occur in immuno compromised
both have extended spectrum resistance to beta-lactams

Klebsiella- lobar pneumonia (red currant jelly) in alcoholics and diabetics

Pseudomonas- CF pneumonia; BE PSEUDo
Strep pneumonia
Pneumococcal warrior
Pneumonia is to Parents what
Group B strep is to Babies
both cause meningitis and pneumonia in their respective groups
What can Hib cause?
Meningitis, acute epiglottitis, septic arthritis, sepsis
What does Hib need to grow?
chocolate agar, factors V and X
Neisseria meningitidis
gram
shape
gram negative diplococci
Strep pneumonia
gram
shape
Gram positive
lancet shaped diplococci
Enterotoxigenic E.Coli
traveler's diarrhea, rice water stool

Heat labile (just like cholera toxin) and heat stabile toxin

Tx: anti-motility and antibiotics
Enteroaggregative E. Coli
forms aggregate patterns and biofilms

destroys cells and mucus secretion

pts get watery, mucoid diarrhea (1/3 bloody)

Sticks arounds (17 days in children)
Enteropathogenic E. Coli
occurs in infants in developing countries

causes effacement of enterocytes and pedestal formation causing malabsorption and diarrhea
Enterohemorrhagic E. Coli
Hs- causes bloody diarrhea, 5Bs, 1A

Hamburger meat in industrialized world

Hemolytic uremic syndrome

Shiga-like toxin, inhibits 60s ribosome causing intestinal cell death
DONT give anti-motility agents; want to get rid of bloody diarrhea of course!

has leukocytes in stool
Enteroinvasive E.coli
Like Shigella
invade epithelial cells

causes immune reaction with FEVER

bloody diarrhea with WBCs (like shigellosis)
Typhoid fever (salmonella typhi)
infects gall bladder and biliary system

Vi capsule gives it extra virulence with pathogenicity island

invades M cells (APC cells of gut), invade lymphoid tissue, invade macrophages, to multiple organ systems

after 7-14d, gets into bloodstream, relative bradycardia, fever, coated tongue, petechiae
Salmonellea enterocolitis
causes diarrhea

result of improper food handling in industrialized countries

food poisoning assoc with picnics

RUFFLES engulf organism
Shigella
like enteroinvasive E. Coli

causes dysentery, bloody mucus containing stools, painful defecation and tenesmus
Campylobacter jejuni
Camping bacteria (zoonotic) in jejunum with nothing better to do than cause bloody diarrhea

oxidase positive

prodrome of fever and headache
Vibrio cholerae (cholera)
curve shaped gram negative adheres to jejunum to colon

oxidase positive

needs a large infecting dose

5B:1A toxin, increase fluid secretion just like heat labile toxin of enterotoxigenic E. Coli.

rapid onset of extreme rice water diarrhea