Gram Negative and Other Bacteria Flashcards
What are the gram negative cocci
N. meningitidis
N. Gonorrhoae
Moraxella catarrhalis
All are oxidase +
How to differentiate b/w the two neisserias
Meningitidis: Fermenter
Gonorrhea: Non fermenter
What are the coccoid rods
H Influenza
B pertussis
Pasteurella
Brucella
How are the gram negative rods differentiated?
Lactose fermenter - pink
Lactose non fermenter
What are the lactose fermenting GNR’s?
Klebsiella Ecoli Enterobacter Citrobater Serratia
What are the slow lactose fermenters
citrobacter
serratia
What are the lactose nonfermenters?
White colonies: Shigella Salmonella Proteus Pseudomonas (oxidase +)
What are the fast lactose fermenters
Klebsiella
E coli
Enterobacter
How are the lactose nonfermenters differentiated?
If they have oxidase
Oxidase positive gram negative rod
Pseudomonas
What gram negative bacteria are curved or comma shaped?
Campylobacter jejuni
Vibrio cholera
H Pylori
Neisseria
Gram negative diplococci
Both ferment glucose and make IgA proteases
N. Gonorrhea clinically
Urethritis, PID, STI
Can travel in blood and cause septic arthritis, conjunctivitis
N. gonoccoi structure
Maltose non fermenter
Gram neg diplococci
No polysaccharide capsule
1st line tx for N gonorrhea
Ceftriaxone
N. Meningococci transmission
Respiratory and oral secretions
N. meningococci structure
Maltose fermenter
Polysaccharide capsule
What bug can cause Waterhouse-Friedrichsen syndrome
N. meningitidis
Prophylaxis for meningococci
Rifampin, ciprofloxacin, ceftriaxone
Treatment for meningococci
Ceftriaxone or PCN G (only after culture)
Haemophilus influenza structure
Gram neg coccoid rod
What does H Flu cause
Epiglottitis Meningitis Otitis media Pneumonia Sinusitis
Thumb sign on XR
Thickening of epiglottis = H Flu epiglottitis
Treatment of H Flu
Treat mucosal infxn w/amoxicillin+/- clavulanate
Treat meningitis with ceftriaxone
What’s most invasive form of H flu
Capsular type B (there’s a vaccine now)
What does H flu produce
IgA protease
How to culture H Flu
Chocolate agar w/factors V and X
Hemophilus ducreyi
Causes chancroid - painful solitary genital ulcer
Legionella pneumophila
Gram negative rod but stains poorly so use silver stain
What do you have to grow legionella on
Charcoal yeast extract culture with iron and cysteine
How is legionella diagonsed
Antigen in urine
Transmission of legionella
NO person to person
Aerosol transmission from environmental water source habitate
Tx of legionella
Macrolide (erythromycin) or quinolone
Pseudomonas aeurginosa
Gram negative rod Oxidase positive Lactose non fermenter Moist environments Blue-green pigment
Infxns from pseudomonas
PNA - cystic fibrosis Otitis externa UTI Osteomyelitis - diabetics Sepsis Contaminates medical equipment and catheters Associated with burn and wound infections Hot tub folliculitis
Pseudomonas toxin
Exotoxin A - inactivates EF-2 - cell necrosis
Tx of pseudomonas
Piperacillin, Ticarcillin
Cefepime, ceftazidime
Imipenem, meropenem
H Pylori triple therapy
PPI + Clarithromycin + either amoxicillin or metronidazole
Gram negative, oxidase positive, diplococci
N gonorrhea or N meningitidis
Sepsis, DIC, adrenal hemorrhage
N. meningitidis
5 year old w/pharyngitis, drooling, and x ray reveals thumb sign
H flu type B (epiglottitis)
What are the virulence factors of E Coli
Fimbriae
K Capsule
LPS endotoxin
What does K capsule of E coli cause
PNA, neonatal meningitis
What does fimbriae of E coli cause
Cystitis, pyelonephritis
What does LPS endotoxin of E coli cause
Septic shock
What does EIEC strain of E coli do
Invades intestinal mucosa and causes necrosis and inflammation
Similar to shigella
Presentation and treatment of EIEC
Fever + bloody diarrhea
Tx: Fluoroquinolones
Toxin and mechanism of ETEC
Produces heat labile and heat stable enterotoxins
No inflammation or invasion
Presentation of ETEC
Travelers diarrhea - watery, similar to cholera
Toxin and mechanism of EPEC
No toxin produced
Adheres to apical surface and flattens villi which prevents absorption
Presentation of EPEC
Diarrhea, usually in kids
EHEC presentation and treatment
Dysentery, HUS (Anemia, thrombocytopenia, ARF)
Tx = supportive
How to differentiate EHEC from other E Coli strains
It does not ferment sorbitol
What is klebsiella
Gram negative rod, fast fermenter of lactose
Red currant jelly sputum
Klebsiella
What does Klebsiella cause
Intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated
Mucoid colonies caused by abundant polysaccharide capsules
Nosocomial UTI
What are the 4 A’s of klebsiella
Aspiration pneumonia
Abscess in lungs and liver
Alcoholics
diAbetics
How are salmonella and shigella similar
Both cause bloody diarrhea and fever, both do not ferment lactose and both are oxidase negative
Salmonella typhi clinical presentation
Typhoid fever
Rose spots on abdomen, fever, HA, diarrhea
Can stay in gallbladder and cause carrier state
Treatment of shigella
Fluoroquinolones
How is shigella spread in body
Cell-cell - no hematogenous spread
How is shigella spread in environment
Humans and primates
Cellular response of salmonella vs shigella
Salmonella: Monocyte response
Shigella: PMN infiltration
What is campylobacter jejuni
Gram negative oxidase + comma shaped, grows in hot temperature.
What does campylobacter cause
Guillain-Barre, reactive arthritis, bloody diarrhea in kids
What is vibrio cholera
Gram negative oxidase + comma shaped. Grows in alkaline media
How does vibrio cholera produce rice water diarrhea
Heat labile endotoxin permanently activates Gs, increasing cAMP.
What does Yersinia enterocolitis cause
Mesenteric adenitis that can look like appendicitis or crohn’s disease
How is yersinia transmitted
Pet feces (puppies), contaminated milk, or pork
What is yersinia
Similar to shigella and salmonella, it’s a gram negative rod, non lactose fermenting and oxidase negative.
What is borrelia
Spirochete - spiral shaped bacteria w/axial filaments, only spirochete that can be visualized on LM
What is Leptospira interrogans
Spirochete that causes leptospirosis
What is leptospirosis
Flu like symptoms, jaundice, photophobia with erythema
Who is leptospirosis found in
Surfers, in the tropics
It’s found in water contaminated with animal urine
What is Weil disease
Icterohemorrhagic leptospirosis
Severe form of leptospirosis with jaundice and azotemia (kidney and liver dysfunction), fever, hemorrhage, and anemia
What is the natural vector for Borrelia burgodrferi
Mouse
The tick can transmit it
Treatment of Lyme disease
Doxycycline, Ceftriaxone
What characterizes the Bell’s palsy of Lyme disease
Bilateral and affects forehead
What is an Argyll Robertson pupil
Constricts with accomodation but is not reactive to light
Associated with tertiary syphilis
What are some causes of VDRL false positives
VDRL detects nonspecific antibody that reacts w/beef cardiolipin Viruses - mono, hepatitis Drugs Rheumatic fever Lupus, leprosy
What is the treatment for all rickettsial diseases
Doxycycline
What is the rickettsial triad
Headache, fever, rash (vasculitis)
What causes rocky mountain spotted fever
Rickettsia rickettsii - obligate intracellular
Clinical pres of RMSF
Rash that starts at wrists and ankles, then spreads to trunk, palms, and soles
What causes Typhus
R. typhi - endemic
R. prowazekii - epidemic
What is the rash like in typhus
Rash starts centrally, then spreads, spares palms and soles
Ehrlichiosis
Ehrlichia - vector is tick
Monocytes with morula in cytoplasm
Anaplasmosis
Anaplasma - vector is tick
Granulocytes with morulae in cytoplasm
Q fever agent
Coxiella burnetii - tick feces and cattle placenta release spores that are inhaled.
Q fever presentation
Atypical Pneumonia
How is Q fever unique from other Rickettsia species
No Weil-Felix reaction
Spores that can survive in endospore form
What are the two forms of chlamydia
- elementary body - infectious, enters cell via endocytosis, transforms into reticulate body
- Reticulate body- replicates in cell by fission and reorganizes into elementary bodies
What species of chlamydia cause atypical PNA
C. pneumoniae, C. psittaci
What species of chlamydia can cause reactive arthritis, follicular conjunctivitis, urethritis, and PID
Chlamydia trachomatis
Tx of chlamydia
Azithromycin
Dx of chlamydiae
Giemsa or fluorescent aby-stained smear shows cytoplasmic inclusions
Lymphogranuloma venerum
Types L1-L3 of chlamydia trachomatis cause small painless ulcers on genitals that cause swollen and painful inguinal lymph nodes which ulcerate.
Tx = doxycycline
What is the classic cause of atypical walking pneumonia
Mycoplasma pneumoniae
Lab findings in mycoplasma pna
High titer of cold agglutinins (IgM) that can agglutinate or lyse RBCs
How is mycoplasma pneumo grown
Eaton agar
Tx of mycoplasma pneumo
Macrolide, doxycycline, or fluoroquinolone
NO pcn - no cell wall
What is contained in mycoplasma pneumo bacterial membrane
No cell wall
Membrane contains sterols for stability