Micro (G-) Flashcards
Which bugs grow pink colonies on MacConkey agar?
Teset with MacConKEE’S agar
Citrobacter
Klebsiella
E.coli
Enterobacter
Serratia
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
E.Coli
Gram-negative diplococci. Both ferment glucose and produce IgA proteases.
Neisseria
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?
Capsule?
Maltose fermentation?
Glucose fermentation?
Transmission?
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.
Dx
Tx
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:
Pneumonia
Sepsis
Otitis Externa (swimmer’s ear)
UTIs
Drug use
Diabetes
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
Tx:
Extended-spectrum β-lactams (e.g.,piperacillin, ticarcillin, cefepime)
Carbapenems (e.g., imipenem, meropenem)
Monobactams (e.g., aztreonam)
Fluoroquinolones (e.g., ciprofloxacin)
Aminoglycosides (e.g., gentamicin,tobramycin)
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
- Cycstitis and Pyelonephritis
- pneumonaie adn neonatal meningitis
- Septic shock
- Fimbriae—cystitis and pyelonephritis;
- K capsule—pneumonia, neonatal meningitis
- LPS endotoxin—septic shock.
Microbe invades intestinal mucosa and causes necrosis and inflammation. Clinical manifestations similar to Shigella. Very invasive and causes dysentary
Dx.
EIEC
- Produces heat-labile and heat-stable enteroToxins. No inflammation or invasion.
- 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
Women comes in complaining of foul smelling lady parts and gray discharge. After dx her you assure her it isn’t an STD.
Whats the Dx and characteristics of organism?
Tx?
Gardnerella Vaginalis:
A pleomorphic, gram-variable rod involved in bacterial vaginosis (Associated with sexual activity, but not sexually transmitted)
Clue cells, or vaginal epithelial cells covered with Gardnerella bacteria (“stippled” appearance along outer margins), are visible under the microscope
Treatment: Metronidazole or clindamycin.
Your friend talks about an interesting case she saw in the ID department when she was rotating through a hospital in North Carolina. A young man came in with a rash all over his trunk but said it started on his wrists and ankles. Prior to the rash he had a fever of 101 and a bad headache.
What is the responsible organism?
Tx?
Characteristics of organims?
Rickettsia rickettsii= Rocky mountain spotted fever with tick as vector: get a rash on hands and feet
Tx = Doxycycline
Characterstics: obligate intracellular organims; needs coA and NAD+; cant make it’s own ATP
Patient presents with headache, muscle aches, and fatigue. In a culture you see these berry like inclusions. What is the Dx?
Do you see a rash with this?
Eherlichiosis: Ehrlichia (type of ricketsial disease), vector is tick. Monocytes with morulae (berry-like inclusions) in cytoplasm.
Rash is rare, tx with Doxycycline
An 35 yo man comes to the office complaining of persistant SOB and cough for the past two weeks. He works from home, has 2 children and has not significant travel hx except, he laughs, taking his kids to the petting zoo! CXR shows right lobar consolidation.
What is the most likely Dx?
What is he at risk for if not tx?
How did he aquire this?
Coxiella burnetii= Q fever, no arthropod vector. Spores inhaled as aerosols from cattle/sheep amniotic fluid. Presents as pneumonia.
May cause endocarditis: Most common cause of culture ⊝ endocarditis.
Got while at the petting zoo; Q fever is Queer because it has no rash or vector and its causative organism can survive outside in its endospore form. Not in the Rickettsia genus, but closely related.
25 yo male comes in with bad headeache, and a nonproductive cough. His commanding officer said he should get looked at. CXR show diffuse interstitial infiltates that would indicate the pt should feel much worse then they do.
You culture the sputum and see they can agglutinate and lyse RBCs and there is a high titer of cold agglutinins (IgM)
Dx?
What do you tx with?
How does this gram stain?
Mycoplasma pneumoniae ; walking pneumoniae
Treatment: macrolides, doxycycline, or fluoroquinolone (penicillin ineffective since Mycoplasma have no cell wall).
*No cell wall. Not seen on Gram stain. Pleomorphic
Classic cause of atypical “walking” pneumonia (insidious onset, headache, nonproductive cough, patchy or diffuse interstitial infiltrate). X-ray looks worse than patient. High titer of cold agglutinins (IgM), which can agglutinate or lyse RBCs. Grown on Eaton agar.; Frequent outbreaks in military recruits and prisons
