Micro (G-) Flashcards Preview

Step 1 Prep > Micro (G-) > Flashcards

Flashcards in Micro (G-) Deck (57)
Loading flashcards...

Which bugs grow pink colonies on MacConkey agar?

Teset with MacConKEE'S agar







What bugs ferment Lactose?

Which one does it really fast and why? 

Lactose is KEE

Klebsiella, E. Coli, Enterobacter

Klebsiell and E.Coli are fast

E.Coli has a B-galactosidase that breaks down lactose into glucose and galactose


IN EMB agar, we see lactose fermenster growing as purple/black colonies. 

Will show up as purple colonies with a green sheen



Gram-negative diplococci. Both ferment glucose and produce IgA proteases.



N. Gonorrhea is a huge pain the ass. What diseases does it cause?

Why can't we make a vaccine for it?

How is it trasmitted? Can we prevent it's transmission?

Causes gonorrhea, septic arthritis, neonatal conjunctivitis, pelvic inflammatory disease (PID), and Fitz-Hugh–Curtis syndrome

No vaccine due to antigenic variation of pilus proteins

Sexually or perinatally transmitted

Condoms sexual transmission. Erythromycin ointment prevents neonatal transmission

Treatment: ceftriaxone + (azithromycin or doxycycline) for possible chlamydial coinfection 


Young lady come to office with horrible pain in her left knee. It is warm and erythematous. During her social history she admits to having unprotected sex several weeks ago and thought she had a yeast infection for which she got treatment from her phamacist but it hasn't gone away. 

What is the Dx?

What are some other complications that present with this disease?

What should we tx her with?

Dx is Neisseria Gonorrhea

Presents with discharge that women may mistake for yeast infection. See PID which may lead to infertility and can cause septic arthritis, causing her knee pain. 

Tx: Ceftriaxone (+Azihtromycin or Doxyclcine to cover for Chlamydia)


Your friend's brother is back home from college and has been feeling like shit. He has fever with joint pain and say's it hurts to turn his head. He prefers to stay in his room in the basement as the light makes his headache worse. When you stop over to see him, you notice he has a dark rash on his lower legs and tell him he needs to get to the ER NOW! What is the DX?

What is a severe complication from this?

How do you tx this pt?

What should you and your friend take to prevent getting this?

Neisseria Meningiditis: you can get meningococcemia and TTP form this and in bad siutaitons Waterhouse-Friderichsen syndrome or even DIC

Treatment: ceftriaxone or penicillin G 

Rifampin, ciprofloxacin, or ceftriaxone prophylaxis in close contacts



What is the difference between N. Meningitis and Gonorrhea?


Maltose fermentation?

Glucose fermentation?


Meningitis: POlysaccharide capsule, ferments glucose AND maltose and transmitted via oral and respiratory secreations

Gonorrhea: NO capsules, CANT ferment maltose (can glucose) and sexually transmitted


This small Gram (-) rod is resposible for lots of diseaes and transmitted via aersolization. 

Makes and IgA protease

What diseases does it cause?

What do we culture it on?

HaEMOPhilus influenzae 

Causes Epiglottitis, Meningitis, Otitis Media, Pneumonia

Culture on Chocolate agar with factors V (NAD+) and X (hematin)


Little boy comes in with bad sore throat and difficulty breathing. You take a xray and it's posted below.

What medications do you prescribe for this pt?

What would you give if this were to cause meningitis?

Treat mucosal infections with amoxicillin +/− clavulanate.

Treat meningitis with ceftriaxone. Rifampin prophylaxis for close contacts. 


What do we give children to prevent epiglotitis?

What is special about this vaccine?

When is it given?

Vaccine contains type b capsular polysaccharide (polyribosylribitol phosphate) conjugatedto diphtheria toxoid or other protein. Given between 2 and 18 months of age.

 Does not cause the flu (influenza virus does). 


 A group of individuals comes down with unilateral lobar pneumonia. The pt had a fever and GI disturbance and are crrently hyponatermic. The doctors make a diagnosis based on an antiG they detected in the pts urine. 



How would you culture this organims?


Dx: Legionella pneumophila 

Tx: Macrolide or Quinolone

Gram-negative rod. Gram stains poorly—use silver stain. Grow on charcoal yeast extract culture with iron and cysteine.


Weird stuff I never knew about Legionella, but hey..

 Detected by presence of antigen in urine. Labs may show hyponatremia.

(remember also causes Pontiac fever! milder form!)


Aerobic, motile, gram-negative rod. Non-lactose fermenting, oxidase ⊕. Produces pyocyanin (blue-green pigment A ); has a grape-like odor. Produces endotoxin (fever, shock) and exotoxin A (inactivates EF-2). 

Pseudomonas aeruginosa 


PSEUDDOmonas is associated with: ƒ

ƒ Sepsis
ƒ Otitis Externa (swimmer’s ear)
ƒ UTIs

ƒ Drug use
ƒ Diabetes
ƒ Osteomyelitis (e.g., puncture wounds) 


You are treating a young girl in the PICU for severe 3rd degree burns and damage to the lungs for inhalation. She is feverish and severily ill. She has ulcers and indurations all around the burns and are discolored. What is the Dx and what can you tx it with?

Pseudomonas Aeruginosa


Extended-spectrum β-lactams (e.g.,piperacillin, ticarcillin, cefepime)

ƒ  Carbapenems (e.g., imipenem, meropenem)

ƒ  Monobactams (e.g., aztreonam)

ƒ  Fluoroquinolones (e.g., ciprofloxacin)

ƒ  Aminoglycosides (e.g., gentamicin,tobramycin)

ƒ  For multidrug-resistant strains: colistin,polymyxin B


Ecthyma gangrenosum—rapidly progressive, necrotic cutaneous lesion caused by Pseudomonas bacteremia. Typically seen in 

immunocompromised patients 


may contribute to chronic pneumonia in cystic fibrosis patients due to biofilm formation.

D/t infection with pseudomonas aeruginosa

Mucoid polysaccharide capsule


Name the virulence factors responsible for the following disease states

1. Cycstitis and Pyelonephritis

2. pneumonaie adn neonatal meningitis

3. Septic shock

1.  Fimbriae—cystitis and pyelonephritis;

2. K capsule—pneumonia, neonatal meningitis

3. LPS endotoxin—septic shock. 


Microbe invades intestinal mucosa and causes necrosis and inflammation. Clinical manifestations similar to Shigella. Very invasive and causes dysentary




1. Produces heat-labile and heat-stable enteroToxins. No inflammation or invasion. 

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


ETEC: travelers diarrhea

EPEC: Diarrhea, usually in children (Pediatrics). 


What bug is responsible for the following triad: anemia, thrombocytopenia, and acute renal failure

This toxin is simular to Shiga toxin

What is the bug responsible and what is the mechanism of the disease process?

EHEC O157:H7 

HUS: triad of anemia, thrombocytopenia, and acute renal failure due to microthrombi forming on damaged endothelium-->mechanical hemolysis (with schistocytes on peripheral blood smear), platelet consumption, and decraesed renal blood flow; microthrombi consume plats leading to thrombocytopenia 


Alcholic is brought to the ER  passed out. He has labored breathing and when he comes to you find out he's homeless and CXR shows lobar pneumonia. 

He coughs up globoid, bloody mucus. What is the dx?

Does this bug have a capsule?

Where is this bug usually found?




An intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated. Very mucoid colonies caused by abundant polysaccharide capsules.

Dark red “currant jelly” sputum (blood/mucus).

Also cause of nosocomial UTIs.


What are the 4 A's of KlebsiellA:

4 A’s of KlebsiellA:

Aspiration pneumonia

Abscess in lungs and liver



Major cause of bloody diarrhea, especially in children. Fecal-oral transmission through person- to-person contact or via ingestion of poultry, meat, unpasteurized milk. Contact with infected animals (dogs, cats, pigs) is also a risk factor. 

camplyobacter jejuni


Describe in as much detail as you can Campylobacter jejuni

What does it condition does it commonly procreed?

Big cause blood diarrhea  in kids

fecal oral transmission and foods like poultry, meat, unpast milk

S shaped, oxidase + and grows at 42 degress (hot a a campfire)

Preceeds Guillan Barre and reactive arthritis


Produces profuse rice-water diarrhea. Endemic to developing countries. Prompt oral rehydration is necessary. 


Mechanism of diesease?

Vibrio cholera

via enterotoxin that permanently activates Gs, INCREASE cAMP. 


Both Salmonella and Shigella are gram-negative bacilli that are_____ fermenters and oxidase ____




can disseminate hematogenously and have flagella with many animal reserviours.

Will produce hydrogen sulfide

Is invasive in intestinal mucosa and causes a monocytic response

Bug responsible?

Do we provide antibiotics?

Does this ferment lactose?


antibiotics may prolong fecal excreation

does NOT ferment lactose


This bug causes diarrhea with cell to cell transmission; NOT hematogenous spread. Doesn't make hydrogen sulfide. Does NOT invade intestinal mucosa and causes PMN infiltration. 

Causitive agent?

Do you provide antibiotics?

Does it ferment lactose?


antibiotics shorten duration of fecal excreation of organism

get bloody diarrhea and does NOT ferment lactose