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Flashcards in Gram negative Bugs Deck (47):

Define the

  • Lactose fermenting enteric bacteria
  • what do they grow on
  • produce what (and what does this thing do)
  • how do they look on EMB agar?

  • Citrobacter, Klebsiella, E. coli, Enterobacter, Serratia (weak fermenter).
  • grow on MacConkey agar (pink)
  • produce Beta-galactosidase:  breaks down lactose into glucose and galactose
  • EMB agar:  grow as purple/blk (E.coli grows purple with green sheen)


Penicillin and gram neg bugs

  • resistance/susceptiblitiy
  • G- moa w/penicillin and vancomycin

  • resistant to penicillin G: susceptible (may be) to penicillin derivatives (ampicillin and amoxicillin)
  • G- outer membrane layer inhibits entry of penicillin G and vancomycin


Define a 

G- diploccoci, both ferment glucose and produce IgA proteases.  

Difference b/t the two

  • Neisseria 
  • Meningoccoci (ferments maltose and glucose) & Gonococci (ferments glucose)
    • N. gonorrhoeae is often intracellular (w/in neutrophils)


Gonococci vs Meningococci 

  • capsule
  • maltose fermation
  • vaccine
  • transmission
  • causes what
  • prevention
  • treatment


  • No polysacchride capsule
  • non maltose fermation
  • no vaccine
  • Sexually transmitted
  • Causes:  gonorrhea, septic arthritis, neonatal conjuntivitis, pelvic inflammtory disease (PID), Fitz-Hugh-Curtis syndrome
  • Prevention:  
    • condoms, prevent sexual transmission.  
    • erythromycin oitment prvents neonatla transmission
  • Treatment:  
    • Ceftriaxone + (axithromycin or doxycycline) for possible chlamydia coninfection


  • Polysaccharide capsule
  • Maltose formation
  • Vaccine is present (except type B)
  • Respirtory and oral secretions
  • Causes:  meningococcemia, meningitis, waterhouse-friderichsen syndrome
  • Prevention:  Rifampin, ciprofloxacin or ceftriazone prophylaxis in close contacts
  • Treatment:  Ceftriaxone or penicillin G


G - rod, stains poorly, used silver stain.  Grow on charcoal yeast extract culture with iron and cysteine. Detected clinically by presence of antigen in urine. Aerosol transmission from environemntal water souce, habitat (e.g. air conditioning systems, hot water tanks).  No person to person transmission. 

  • ID the organism
  • Treatment
  • additional key lab finding

  • Legionella pneumophila
  • Legionnaires' disease:  severe pneuomia, fever, GI and CNS symptoms
  • Pontaic fever:  mild flu like symptoms
  • Labs show hyponatremia


Pt presentation:

Sm gram neg (coccobacillary rod), aerosol transmission. Most invasive disease cause by capsule type B. Non typeable strains cause mucosal infections (otitis media, conjunctivitis, bronchoitis).  Produce IgA protease. Culture on chocolate agar requires, factos V (NAD+) and factor X (hematin) for growth.  can also be grown with S. aureus, which provides factor V.  

Causes: Epiglottitis (cherry red in children) meningitis, ortitis media and pneumona (E-MOP).

  • Id the organism
  • Prevention
  • Treatment

  • Haemophilus influenzae
  • Prevention:
    • Vaccine contains type B capsular polysaccharide (polyribosylribitol phosphate) conjugated to diphtheria toxoid or other protein. 
    • Given 2-18 mo of age
    • does not cause flu!
  • Treatment
    • Mucosal infection:  amoxicillin +/- clavulanate
    • Meningitis: ceftriaxone, (Rifampin prophylaxis in close contacts)


Aerobic gram - rod, non lactose fermenting, oxidase +, produces pyocyanin (blue green pigment), has a grape like odor.  Water source. Produces endotoxin (fever shock, and exotoxin A (inactivates EF-2).

Assocaited w/:  wound and burn infections, pneumonia (especially in cystic fibrosis) sepsis, external otitis (swimmer's ears), UTI, Drug use and Diabetic osteomyelitis, hot tub folliculitis.  Malignant otitis externia in diabetics.

  • Define organism
  • Define Ecthyma gangrenosum
  • treatment
  • Assoc with CF pt

  • Pseudomonas aeruginosa
  • Ecthyma gangrenosum:  rapidly progressive, necrotic cutaneous lesions, caused by Pseudomanas bacterium.  Typically seen in immunocompromised pts.
  • Treatment:  
    • aminoglycoside + extended- spectrum penicillin (piperacillin, ticarcillin, cefepime, imipenem, meropenem).
  • Chronic pneumonia in CF pt is associated with biofilm.


Define the 3 virulence factors of E. Coli

  • Fimbriae:  cystitis ad pyelonephritis
  • K capsule:  pneumonia, neonatal meningitis
  • LPS endotoxin:  septic shock


No toxin produced,  Adheres to apical surface, flattens villi, prevents absorption.

  • Define strain and presentation

  • EPEC
  • Diarrhea usually in children (Pediatrics)


Microbe invades intestinal mucosa and causes necrosis and inflammation.  Clinical manifestations similiar to Shigella.

  • Define strain & presentation

  • EIEC
  • Invasive, dysentery


Produces heat labile and heat stable enteotoxins.  No inflammation or invasion.

  • Define strain and presentation

  • ETEC
  • traveler's diarrhea (watery!!!!)


Salmonella vs Shigella

  • flagella
  • transmission
  • reservoirs animals or humans
  • production of hydrogen sulfide
  • Antibiotics on fecal excretion
  • invades inteatinal mucosa and causes what?
  • bloody diarrhea
  • lactose fermentation


  • flagella present (think salmon swim)
  • Transmission: disseminate hematogenously
  • reserevoirs animals
  • produces Hydrogen sulfid
  • antibiotics prolong fecal excretion of organism
  • monocytic response
  • causes bloody diarrhea
  • does not ferment lactose


  • No flagella
  • cell to cell transmission, no hematogenous spread
  • reservoir humans and primates
  • DOES not produce hydrogen sulfid
  • antibiotics shorten fecal excretion
  • invades intestinal mucosa and causes PMN infiltration
  • Often causes bloody diarrhea
  • Does not ferment lactose


O157:H7 is the most common serotype.  Produces shiga-like toxin that causes Hemolytic-uremic syndrome (triad of anemia, thrombocytopenia, and acute renal failure). 

Microthrombi form an endothelium damaged by toxin--> mechanical hemolysis (schitocytes formed) and dec renal blood flow; microthrombi consume platelets--> thrombocytopenia.

  • Define strain and presentation

  • EHEC
  • Presentation
    • Dysentery (toxin alone causes necrosis and inflammation)
    • Does not ferement sorbitol (distinguishes it from other E. coli


an intestinal flora tha cause lobar pneumonia in alcoholics and diabetics when aspirated.  Very mucoid colonies caused by abundant polysaccharide capsules.  Red 'current jelly' sputum.

Also cause of nosocomial UTIs

  • Define organism and presentation of 4 A's

  • Klebsiella
  • Presentation
    • aspiration pneumonia
    • Abscess in lungs and liver
    • Alcoholics
    • di-A-betics


found only in humans, characterized by rose spots on the abdomen, fever, headache, diarrhea.  Can remain in gallbladder and cause a carrier state.

Salmonella typhi


Many cause of bloody diarrhea, especially in children.  fecal oral transmission through foods such as poultry meat, unpasteurized milk.  comma or s-shaped oxidase + grows at 42oC .

  • Define organism
  • Common antecedent to what 2 diseases

  • Campylobacter jejuni
  • GBS (guillain-Barre syndrome) and reactive arthritis


Produces profuse rice water diarrhea via enterotoxin that permanently activates Gs, increase cAMP. comma shaped, oxidase +, grows in alkaline media.  Endemic to developing countries.

  • Define the organism
  • What is the treatment

  • vibrio cholera
  • prompt oral rehydration


Usually transmitted from pet feces (puppies) contaminated milk or pork.  


  • define the organism
  • Causes mesenteic adenitis that can mimic what 2 conditions?

  • Yersinia enterocolitica
  • Crohn disease or appendicitis


Causes gastritis and peptic ulcers (especially duodenal).  Risk factor for peptic ulcer, gastric adenocarcinoma and lymphoma.  Curved gram negative rod that is catalse, oxidase and urease + (can use urea breath test or fecal antigen test for diagnosis).  Creates an alkaline environment.

  • Define the organism
  • What is the treatment?

  • Helicobacter pylori
  • Triple therapy:
    • PPI (proton pump inhibitor)
    • Clarithromycin
    • (either amoxicillin or metronidazole)


  • Define the 3 types of spirochetes (spiral shaped bacteria with axial filamnets)
  • which one can be visualized
    • via aniline dyes in light microscope
    • dark-field microscopy

  • Borrelia, Leptospira, Treponema
    • Aniline dyes:  Borrelia
    • Dark field:  Treponema


Found in water with animal urine, causes leptospirosis; flu like symptoms jaundice, photophobia with conjunctial suffusion (erythema w/o exudate). Prevalent amon surfers and in tropics (Hawaii)

  • What is the organism
  • assocaited with what diesase?

  • Leptospira interrogans
  • Weil disease:  (icterohemorrhagic leptospirosis) severe form with jaundice and azotemia from liver and kidney dysfunction;  fever, hemorrhage and anemia.


Common in northeastern US.  

  • inital symptoms:  erythema chronicum migrans (bull's eye rash'), flu like symptoms, +/- facial nerve palsy.
  • later symptoms:  monoarthrits (large joints) and migratory polyarthritis, cardiac (AV nodal block), neurologic (encephalopathy, facial nerve palsy, polyneuropathy).


  • What is the disease and Caused by what 
  • Transmitted by what
  • Treatment?

  • Lyme disease borrelia burgdorferi 
  • transmitted by:  Ixodes tick (vector of Babesia)
  • Treatment:  doxycycline, ceftriaxone.


What is syphilis caused by?


  • Treponema pallidum
  • Treatment: Penicillin G


Localized disease presenting with painless chancre.  If avaloiabel use a dark field microscopy to visualze in fluid from chancre.

  • What is the disease
  • What is the serologic testing

  • Primary syphilis
  • VDRL/RPR (non specific) confirm diagnosis with (FTA-ABS specific)


Disseminated disease with constitutional symptoms maculopapular rash (palms and soles) condylomata lata (also confirmable with bark field microscopy)

  • What is the disease
  • What is the serologic testing
  • Is it localized or systemic

  • secondary syphilis
  • Serologic testing:  VDRL/RPR (non specific, confirm diagnosis with specific test (FTA-ABS).
  • Systemic, latent syphilis follows.



gummas (chroic granulomas) aortiis (vasa vasorum destruciton) neurosyphilis (tabes dorsalis, general paresis) Argyll Robertson pupil

  • What is the disease
  • What are the signs
  • What do you with neurosyphilis

  • Tertiary syphilis
  • Signs: board based ataxia, + Romberg, Charcot joint, stroke w/o HTN.
  • For neurosyphilis: test spinal fluid with VDRL or RPR.


Pt presents with saber shins, saddle nose, CN VIII deafness, Hutchinson teeth, mulberry molars.

  • What is the disease
  • How do you prevent

  • Congenital syphilis
  • Prevent:  treat mother early in pregnancy as placental transmission typically occurs after first trimester.


What is argyll robertson pupil?

constricts wit accommodation but not reactive to light (assoc with 3 syphilis)


What are VDRL false positives?

What can cause it?

  • VDRL detects nonspecific antibody that reacts with beef cardiolipin.
    • Inexpensive, widely available test for syphilis, quantitative, sensitive, but not specific.
  • Viruses (mono, hepatitis), Drugs, Rheumatic fever, Lupus and Leprosy.


Define a Jarisch-Herxherimer reaction

what causes it?

  • Flu like syndrome after antibiotics are started
    • due to killed bacteria releasing pyrogens.


A pleomorphic gram variable rod that is involved in vaginosis.  Presents as a gray vaginal discharge with fishy smell; nonpainful (vs vaginits).  Associated with sexual activity, but not sexually transmitted.   Clue cells coverd with certain bacteria are present under the microscope.

  • Define the organism
  • Treatment:

  • Gardnerella vaginalis
  • Treatment: metronidazole or (to treat anaerobic bacteria) clindamycin


what do you use to treat all rickettsial diseases and vector borne illness?



Disease occurs primarily in the sourht atlantic states, especially N. Carolina.  Rash typically starts at wrist and ankeles and then spreads to teh truck, palms, and soles.

Classic triad:  headache, fever, rash (vasculitis)

  • Define the disease
  • Name the vector
  • describe what it is (obligate, facultative, etc.), and what it needs to synethesis ATP

  • Rocky Mountain spotted fever
  • Rickettsia rickettsii
  • Obligate intracellular organism: NAD+ and CoA (due to the fact it can not synthesis ATP on its own).

-Palms adn soles rash is seen in Coxsackevirus A infection (hand, foot, mouth disease)

-Rocky MSF & 2o syphilis (you drive CARS using your palms and soles)


Rash starts centerally and spreads out, sparing palms and soles

  • What is the disease?
  • Endemic is caused by what bug?
  • Epidemic is caused by what bug?

  • Typhus
  • Endemic (fleas)--> R. typhi
  • Epidemic (human body louse) R. prowazekii

Rickettsii on the wRists, Typhus on the Truck


Monocytes with morulae (berry like inclusions) in cytoplasm

  • what is the disease
  • what is the vector

  • Ehrlichiosis
  • Ehrlichia


Granulocytes wit h morulae in cytoplasm

  • What is the disease?
  • What is the vector?

  • Anaplasmosis
  • Anaplasma


A tick feces and cattle placenta release spores that are inhaled as aerosols.  Presents as pneumonia.

  • What is the disease?
  • What is the vector?
  • What is the causitive organism?

  • Q fever
  • No vector
  • Coxiella burnetti

Q fever is Queer b/c it has no rash or vector  and its causitive organism can survive outside in its endospore form.  Not in the Rickettsia genus, but closely related.


Chylamydiae cannot make their own ATP.  They are obligate intracellular organisms that cause mucosal infections.  

What are the 2 forms (and their func) that chylamydiae come in?

  • Elementary body (sm, dense)
    • Enfections & Enters cell via Endocytosis
    • transforms into reticulate body
  • Reticulate body 
    • Replicates in cell by fission
    • reorganizes into elementary bodies


What species of Chlamydia causes

  • reactive arthritis (Reiter syndrome)
  • follicular conjunctivitis
  • Nongonococcal urethritis and PID

Chlamydia trachomatis


What 2 species of Chlamydia cause atypical pneumonia?

How are they transmitted?

  • C. pneumonia & C. Psittaci
  • transmitted by aerosal


  • What is the 2 types of treatments for Chlamydia (which on is favored and why)
  • Lab diagnosis?
  • how is this organism unusual?


  • Azithromycin (favored b/c of one time treatment) and Doxycycline
  • Lab diagnosis cytoplasmic inclusions seen on Giemsa or fluorescent antibody- stained smear
  • Unusual Chlaymdial cell wall lacks muramic acid.


What are the 3 Chlamydia trachomatis serotypes?

  • Types A, B, & C
  • Types D-K
  • Types L1, L2, & L3


Which of the Chlamydia trachomatis serotypes causes:

  • Chronic infection, causes blindness due to folllicular conjunctivitis in Africa.

  • Types A, B, and C

Africa/Blindness/Chronic infection


Which of the Chlamydia trachomatis serotypes causes:

  • Urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis.

  • Types D-K= everything else
  • neonatal disease can be acquired durign passage through infected birth canal.

D**K is where you would get the urethritis.


Which of the Chlamydia trachomatis serotypes causes:

  • Small, painless uclers or genitals--> swollen painful inguinal lymph nodes that ulcerate (buboes) 
    • What is this termed as
  • How do you treat?

  • Types L1, L2, L3
  • Lymphogranuloma venerum
  • Treatment: doxycycline


Pt presents with

-Insidious onset, headache, nonproductive cough, patchy, or diffuse intersititial infiltrate.

-X-ray looks worse than patient

  • What is the disease
  • High titer of what?
    • which can agglutinate or lyse RBC.
  • Grown on what?
  • Treated with what?

  • Mycoplasma pneumoniae
  • high titer:  cold agglutinins (IgM)
  • Grown on Eaton agar
  • Treatment:  macrolides, doxycycline or fluoroquinolone (penicillin ineffective since mycoplasma have no cell wall).



  • No cell wall. not seen on                 .
  • Bacterial membrane contains               for stability
  • freq outbreaks in                &                 .
  • Mycoplasmal pneumonia is more common in pts <30 yrs old.

  • Giesma stain
  • sterols 
  • military recruits and prisons