Microbio: Gram Negative Flashcards
gram negative stain
pink in color
gram negative oxidase positive, comma shaped
campylobacter, vibrio cholera, helicobacter pylori
gram negative diplococci
Neisseria meningitidis and Neisseria gonorrhea
how to distinguish neisseria meningitis from neisseria gonorrhea
minigitidis- maltose fermenter
gonorrhea- non maltose fermenter
gram negative coccoid rods
these are often times called "coccoid rolds" haemophilus influenzae pasturella brucella bordetella pertussis
gram negative rods- how to tell them apart?
lactose fermenter or not
lactose fermenting gram negative rods
can be fast fermenter and slow fermenter
fast fermenting gram negative, lactose fermenting rods
Klebsiella and Ecoli
slow fermenting gram negative, lactose fermenting rods
serratia, cirtobacter and others
non lactose fermenting gram negative rods can be separated based on…
oxidase positivity
oxidase negative gram negative rods
Shigella, salmonella, proteus, yersinia
oxidase positive gram negative rods
pseudomonas
lactose fermenting enteric bacteri
grow pink colonies on Mac Conkey agar. things like citrobacter, klebsiella, E coli, Enterobacter and Serratia
E coli on MacConkey agar
grows pink because it produces a beta galactosidase and this breaks down lactose into glucose and galactose. EMB agar- lactose fermenters are usually purple or black but Ecoli has purple colonies with a green metallic sheen
can penicillin be used on gram negative bugs?
not on gram negative bacili because the gram negative outer membrane layer inhibits entry of the penicillin G an vancomycin.
Neisseria
gram negative diplococci. both of the species ferment glucose and produce IgA proteases. N gonorrhea is often intracellular (within the nuetrophils)
what is the difference betwen N meningitidis and N gonorrhea
M ferments maltose and G does not
which Neisseria species has a capsule
N Meningitidis. polysaccharide
Is there a vaccine for the Neisseria species
Yes for N. meningitidis (not for type B)
and No for N. Gonorrhea bc there is antigenic variation of pilus proteins really fast
diseases caused by N meningitidis
meningitis and meningococcemia. can also cause Waterhouse Friedrichson syndrome- bleeding and necrosis of the adrenal gland.
diseases caused by N. gonorrhea
gonorrhea, septic arthritis, neonatal conjunctivitis, PID, and Fitz Hugh Curtis syndrome
treatment of N gonorrhea
ceftriaxone and (azithromycin or doxycycline) for possible chlamydia co infection
treatment for N. Meningitidis
cetriaxone or Penicillin G
Haemophilus influenzae
small gram negative coccobacillary rod. aerosol transmission. most disease is caused by the capsular type B. produces an IgA protease. culture on chocolate agar with factor V and X
medium required for H influenza
needs chocolate agar with factor V (NAD+) and X (hematin)
diseases caused by H influenza
NOT influenza
epiglottitis (cherry red throat in children), meningitis, otitis media and pneumonia
how to treat mucosal infections from H influenza
usually caused by the non typeable strains. treat with amoxicillian +/- clavulanate
how to treat H influenza infections
ceftriaxone. rifampin prophalxais in close contacts
H influenza vaccine
one of the three vaccines that has the B capsular polysaccharide conjugated to a protein. here it is conjuagted to the diptheria toxoid in general. given between ages 2months- 18 months.
legionella- features?
gram negative rod that does not gram stain well
what stain should you use for legionella?
silver stain
what kind of medium do you need for legionella
charcoal yeast extract culture with iron and cysteine added
how do you detect legionella?
antigen in the urine
how is legionella transmitted?
usually airborne to water source habitat like air conditioning or water heaters. no person to person trnasmission.
treatment for legionella
macrolide or quinolone
two diseases caused by legionella infection
legionaries disease and pontiac fever
legionaries disease
severe pneumonia, fever, GI and CNS symptoms
pontiac fever
caused by an infection with legionella. causes mild flu like symptoms
what important lab finding do you see in legionella infection?
hyponatremia
features of pseudomonas aeruginosa
aerobic gram negative rod. non lactose fermenting, oxidase positive.
what kind of pigment does pseudomonas produce
blue green pigment called pyocyanin. has a grape like odor.
which two bugs inhibit protein synthesis with an exotoxin that causes a decrease in elongation factor 2 (EF2)?
pseudomonas aeriginosa and corynbacteria diptheria
does pseudomonas produce endotoxin or exotoxin?
both! endotoxin gives fever and shock while exotoxin A inactivates EF2
what disease gives chronic pneumonia in CF patients
pseudomonas aerginosa
diseases associated with pseudomonas aerginosa infections
PSEUDO: pneumonia (especially in CF), sepsis, external otitis (swimmers ear), UTI, Drug use and diabetic osteomyelitis. also can cause hot tub folliculitis
ecthyma gangrenosum
this is a rapidly progressive necrotic cutaneous lesion caused by pseudomonas aerginosa. mostly seen in imuno compromised patients.
treatment for pseudomonas infection?
aminoglycoside plus extended spectrum penicillin
malignant otitis externa in diabetics
caused by pseudomonas aeriginosa
E coli has 3 virulence factors
fimbrae- cystitis and pylonephritis
K capsule- pneumonia and neonatal meningitis
LPS endotoxin- septic shock
EIEC infection
I is for INVASION. microbe invades the intestinal mucosa and causes necrosis and inflammation. clinical manifestations similar to Shigela. causes dysentery.
ETEC infection
T is for enteroToxins. heat labile and heat stabile enterotoxins. no inflammation and no invasion. T is also for Traveler’s diarrhea
EPEC infection
P is for pediatrics. usually seen in kids.
adheres to the apical surface, flattens villi and prevents absorption
EHEC infection
classic- O157H7- most common serotype. Shiga like exotoxin that produces a hemolytic uremic syndrome (HUS: thrombocytopenia, anemia, and acute renal failure). get mechanical hemolysis (schistocytes formed) and decreased renal blood flow. microthrombi consume platelets. does not ferment sorbitol (distinguishes it from other types).
Klebsiella features
fast fermenter (lactose) with E.coli.
intestinal flora that can cause lobar pneumonia in alcoholics and diabetics when aspirated.
abundant polysaccharide capsules. causes red “current” jelly sputum.
can also cause nosocomial UTIs.
does salmonella or shigella have a flagella
salmonella (swims like a salmon)
how does salmonella spread
hematogenously
how does shigella spread
cell to cell transmission. NOT HEMATOGENOUS
salmonella reservoirs
many of them
shigella reservours
only humans and primates
does salmonella or shigella produce H2S gas?
salmonella
are antibiotics better for salmonella or shigella?
shigella. abx can actual lengthen the time of fecal excretion of the organism in salmonella
what type of cell response is seen in salmonella
monocytes after invasion
what type of cell response is seen in shigella
PMNs after invasion
which of salmonella or shigella more commonly causes bloody diarrhea
shigella more commonly does. both can
which of salmonella or shigella can ferment lactose?
neither
which of salmonella or shigella are oxidase negative
both
bug that causes typhoid fever
salmonella typhi. rose red spots on the abdomen, fever, headache, and diarrhea. can remain in the gallbladder and use a carrier state.
campylobacter jejuni characteristics
this is a gram negative, comma shaped, oxidase positive organism. fecal oral transmission through foods. poultry, meat, unpasteurized milk. comma or s shaped. grows at 42 degrees. “camp likes the hot fire”.
what disease does infection with campylobacter jejuni often come before?
Guillane Barre syndrome (ascending paralysis migrating from hands and feet toward the trunk, with weakness) and reactive arthritis.
what infection gives rice water diarrhea
most commonly vibrio cholera. it does through an enterotoxin that permanently activates Gs, increasing cAMP.
vibrio cholera characteristics
comma shaped organism that is gram negative and oxidase positive. grows in alkaline media.
Helicobacter pylori characteristics
comma shaped, oxidase positive organism. it is also catalase and urease positive. so it is catalase, urease and oxidase positive. creates an alkaline environment.
diseases caused by helicobactery pylori
gastritis, peptic ulcers (most commonly duodenal). risk factor for gastric adenocarcinoma and lymphoma.
how to diagnose h pylori infection
urease breath test or fecal antigen testing.
triple therapy for H pylori infection
PPI + clarithromycin + amoxicillin/metronidazole (flagyl)
what usually transmits Yersnina enterolitica?
usually transmitted by pet feces like puppies, contaminated milk, or pork.
what disease does yersinia enterolitica cause?
mesenteric adenitis (inflammation of abdominal nodes) that can mimic crohns or appendicitis
what are the three important spirochetes?
spiral shaped bacteria with axial filaments. includes…
Borrelia, Leptospira, Treponema (BLT)
how to visualize borrelia
this is the “big” spirochete so it can be seen using aniline dyes (wright or giemsa stain) in light microscopy
how to visualize treponema
requires dark field microscopy
Leptospira interrogans features
found in water contaminated with animal urine.
leptospirosis
flu like symptoms, jaundice and photophobia with conjunctival suffision (erythema without exudate).
who gets leptospirosis
surfers in the tropics like Hawaii
Weil disease
severe infection with leptospira interrogans. also known as icterohemorraghic leptospirosis- severe form with jaundice, azotemia from renal and liver dysfunction, fever, hemorrhage and anemia
what disease is caused by borrelia burgdorfi
lyme disease
what is the vector that transmits lyme disease
Ixodes.. this is also the vector for babesia
natural reservoir for lyme disease
the mouse
rash associated with lyme disease
bulls eye rash called erythema migrans.
early symptoms of lyme disease
erythema migrans, flu like symptoms, can have a facial nerve palsy
late symptoms of lyme disease
monoarthritis (large joints), migratory polyarthritis, cardiac (AV node) block, neurologic things such as encephalopathy, facial nerve palsy, polyneuropathy.
what is important about the facial nerve palsy that can be seen in lyme disease
it is most commonly bilateral
treatment for lyme
doxycycline and ceftriaxone
bacteria that causes syphilis
treponema palidum
treatment for syphilis
Penicillin G
primary syphilis features
painless chancre
dark field microscopy will show the bug
what is serologic testing for syphillis
VDRL/RPR are non specific and you can confirm the diagnosis with specific test like FTA ABS
secondary syphilis features
disseminated disease with constitutional symptoms like maculopapular rash on palms and soles, condylomata lata= wart like lesions on the genitals
tertiary syphilis features
gummas (chronic granulomas), aortitis from vasa vasorum destruction, neurosyphilis (tabes dorsalis or general paresis), argyl robertson pupil. broad based ataxia, positive rhomberg, charcot joints, stroke without hypertension
congenital syphilis signs
saber shins, saddle nose, CN VIII deafness, Hutchinson teeth, mulberry molars. to prevent, treat mother early in pregnancy as placental transmission typically occurs after the first trimester.
argyle robertson pupil
prostitute pupil- accommodates but does not react. associated with tertiary syphillis
false positive VDRL
reacts with beef cariolipin. many false positives including viral infections like mono or hepatitis, drugs, rheumatic fever, lupus and leprosy.
Jarisch Herxheimer reaction
reaction can be seen once penicillin G is started for syphillis. it is flu like symptoms after the abx are started due to killed bacteria releasing pyrogens.
Gardenalla vaginalis
gram variable rod involved in vaginosis. gray vaginal discharge with a fishy odor. non painful- this is different from vaginITIS. overgrowth from abx use or sexual activity but not sexually acquired. clue cells are seen with the bacteria under the microscope.
treatment for vaginosis from gardenala vaginalis
metronidazole or clindamycin (treats anerobics)
anaplasma source
ixodes tick
bartonella transmission
cat scratch. this is cat scratch fever, bacillary angiomatosis
borrelia recurrentis
causes relapsing fever and is transmitted through the louse (recurrent due to variable surface antigens)
brucella
disease: brucellosis/undulant fever. source is unpasturized dairy
campylobacter
bloody diarrhea. from puppies, livestock, ingestion undercooked meat
chlamydophilia psittaci
psitticosis, from parrots or other birds
coxiella burnetii
Q fever, aerosols of cattle or sheep amniotic fluid
ehrlicia chaffeensis
causes erlichiosis, from lone star ticks
francisella tularensis
causes tularemia from ticks, rabbits, deer fly
leptospira
leptospirosis from animal urine
mycobacterium leprae
leprosy; humans with leprosy or the armidillo
pasturella multocida
cellultitis, osteomylitis; animal bite from cat or dog
Rickettsia prowazekii
epidemic typhus; from a louse
rickettsia rickettsii
Rocky mountain spotted fever; dermacentor ticks
Rickettsia typhi
endemic typhus; fleas
Yersinia pestis
plague; rats and prairie dogs are the reservoirs, fleas
how to treat all rickettsia illnesses
doxicycline
things that cause rash on palms and soles
CARS: coxsackie virus A infection (hand foot and mouth disease), Rocky mountain spotted fever, Secondary syphilis
where do you ind rocky mountain spotted fever?
mostly in the southern american states like in North Carolina.
what is classic about the rash in rocky mountain spotted fever?
starts at the wrists and ankles and then spreads to trunk, palms and soles.
classic triad of rocky mountain spotted fever
headache, fever, rash (vasculitis). can look like meningitis at first
what type of organism is rickettsia
obligate intracellular organism that needs CoA and NAD+ because they cannot make their own ATP
classic rash of typhus
this starts centrally on the TRUNK and spreads out. it SPARES the palms and soles
organisms that can cause typus
fleas- R typhi, human louse R prowazekii.
Is a rash common in erlichiosis
rare
vector of erlichiosis
tick
what do you see on histology with erlichiosis
monotcytes with morulae or berry like inclusions in the cytoplasm.
Anaplasmosis vector
tick
Anaplasmosis histology findings
granulocytes with morulae in cytoplasm
what is Q fever
infection with Coxiella burnetti- no arthropod vector. tick feces and cattle placenta releas spores that are inhaled as aerosoles.
how does Q fever present?
pneumonia
what type of organism causes chlamydia
chlamydiae cannot make their own ATP. obligate intracellular organisms that cause mucosal infections.
2 forms of chlamydia. 1) elementary bodies…
elementary bodies (small dense), they infect cells and enter the cell via endocytosis. then transforms into a reticulate body.
2 forms of chlamydia 2)reticulate body…
the reticulate body replicates in the cell by fission and reorganizes into elementary bodies.
lab diagnosis of chlymidia
cytoplasmic inclusions seen on Giemsa or flourescent antibody stained smear. the chlamydial cell wall is unusual in that it lacks muramic acid
what disease is caused by Chlamydia trachomatis
reactive arthritis, follicular conjunctivitis, non-gonococcal urethritis and PID
treatment of chlymidia infections
azithromycin is favored bc 1 dose treatment. can use doxycycline as well
Types A, B, C of Chlymida trachomatis
chronic infection, blindness (from follicular conjunctivitis) and Africa
Types D-K Chlymidia Trachomatis
Urethritis, PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis
Types L1, L2 and L3 chlymidia trachomatis
lymphogranuloma venereum- small, painless ulcers on genitals and swollen painful inguinal lymph nodes that ulcerate.
Mycoplasma pneumoniae
classic cause of atypical or walking pneumonia. symptoms include insidious onset, headache, non productive cough, patchy or diffuse interstitial infiltrate. X-ray commonly looks much worse than the patient.
what lab test is often elevated in walking or atypical pneumonia
IgM cold aggultinins. these can agglutinate or lyse RBCs.
how do you grow up Mycoplasma pneumonia
on eaton agar with cholesterol.
common outbreaks of Mycoplasma pnuemonia
in prisons and military recruits- those under 30 yrs age more commonly infected
Treatment for Mycoplasma pneumonia
macrolide, doxycycline or fluoroquinolone .
can you use penicillin for Mycoplasma pneumonia
No because Mycoplasma have no cell wall
