Gram Negative Bacteria Flashcards
1
Q
Neisseria - Overview
Gram Negative Diplococci
A
2
Q
Neisseria gonorrheae
A
3
Q
Neisseria meningitidis
A
4
Q
People with terminal complement deficiency (c5-c9) are particularly susceptible to which type of gram negative infection?
A
Neisseria infections.
5
Q
Antigenic variation of what in Neisseria infections?
A
Pili
* Hair-like proteins that facilitate attachment to mucosal surfaces
6
Q
Concerning Neisseria complication (as a class, overall)?
A
Disseminated intravascular coagulopathy (DIC)– causing petechial skin rash.
7
Q
Liver pain in a young woman who otherwise has an STD:
A
Fitz-Hugh-Curtis syndrome
* Perihepatitis – infection & inflammation of the liver
* Violin-string adhesions of the peritoneum to the liver
Complication of PID.
8
Q
Necessary co-treatment of gonococcal & chlamydia infections:
A
Gonorrhea
* Ceftriaxone IM injection
Chlamydia
* Azithromycin (macrolides)
* Doxycyclines (tetracyclines)
9
Q
Haemophilus influenzae
A
10
Q
Bordetella pertussis
A
11
Q
H. Flu can be co-cultured with which other organism?
A
Staph Aureus (which provides factor 5 through the breakdown of RBCs).
* Factor 5 (NAD+)
* Factor 10 (hematin)
12
Q
Which organ is mainly responsible for filtering encapsulated bacteria from the blood?
A
Spleen
- This is why asplenic patients are particularly susceptible to infections caused by encapsulated organisms:
- H. flu
- N. meningitidis
- Strep pneumo
- Pseudomonas aeruginosa
- E. coli
- Salmonella
- Klebsiella
13
Q
Epiglottitis (inspiratory stridor) & a patient in tripod position is likely affected with which organism?
A
H. Flu (type B)
14
Q
Medication indications for different H. Flu complications:
A
Sinusitus, otitis media (mucosal resp/airway infections)
* Amoxicillin clavulanate
Meningitis
* Ceftriaxone (IM)
Prophylaxis for close contacts
* Rifampin
15
Q
Organisms that produce culture-negative endocarditis:
A
HACEK
- Haemophilus
- Actinobacillus
- Cardiobacter
- Eikenella
- Kingella
16
Q
Pertussis toxin does what?
A
- activates adenylate cyclase by inhibiting Gi
- increasing cAMP
- increased permeability of the cell membrane
- flow of ions and fluid out of the cell into the extracellular space
- EDEMA
17
Q
3 phases of whooping cough:
A
- Catarrhal phase – low grade fevers and runny nose
- Paroxysmal – intense cough with inspiratory whooop. Can be so severe that the coughs cause vomiting (posttussive emesis)
- Convalesecent – gradual recovery of bronchitis & cough
18
Q
Why could bordetella pertussis be mistaken for a viral infection?
A
Because of the lymphocytic infiltrate resulting from immune response.
19
Q
Gram negative bacteria what color under the microscope (after gram stain)?
A
- Red
- Pink
20
Q
Brucella
A
21
Q
Rx combination to treat Brucella
A
Doxycycline & Rifampin.
- Transmitted through the ingestion of contaminated animal products.
22
Q
Name that organism: Long time smoker with chronic lung disease who is presenting with severe unilateral lobar pneumonia, high fever, CNS symptoms, GI symptoms, and hyponatremia – and many other people on the same cruise ship are affected:
A
Legionella (gram negative rod)
- Causing Legionnaires’ disease (shared water source)
23
Q
Why is Legionella so hard to visualize?
A
Because it’s mainly intracellular (facultative).
24
Q
Hyponatremia will lead to what cardiac finding on physical exam?
A
Bradycardia
25
If a patient has both **diarrhea** (GI symptoms) and **coughing** (lung symptoms), think of this gram negative bacillus:
**Legionella pneumophila**
26
How to Dx Legionella?
Urine antigen test.
27
Legionella pneumophila
28
**Pseudomonas aeruginosa** (characteristics)
29
**Pseudomonas aeruginosa** (virulence factors)
30
Name the offending organism: **Hot tub folliculitis** & **malignant otitis externa**
Pseudomonas aeruginosa
31
The 4 risk factors for Pseudomonas Aeruginosa:
## Footnote
Warm, moist environments
1. **Hot tubs**/pools
2. **Cystic Fibrosis**
3. Ecthyma gangrenosum (**immunocompromised patients**)
4. **Indwelling (foley)** catheter -- causes **UTI**s
## Footnote
Common nosocomial infection.
32
Which 3rd generation cephalosporin is **not effective** for pseudomonas aeruginosa?
* Ceftriaxone
33
**Rx** that is effective for **pseudomonas aeruginosa**?
**1st Line**
1. Piperacillin, Ticarcillin
2. Ceftazidime (3rd gen), Cefepime (4th gen)
**Next -- acquired resistance**
1. Fluoroquinolones (cipro, levo)
2. Carbapenems (mero, imi)
34
**Pseudomonas aeruginosa** (disease)
35
**Salmonella** (overview)
36
How to distinguish **salmonella** and **shigella** (both being **gram negative rods** that are **oxidase-negative** and **don't ferment lactose**)?
**Hydrogen Sulfide test**
* Only **Salmonella** produces **H2S** & black precipitate on **iron agar**?
**Motility test**
* **Salmonella** is **motile**
* Shigella is non-motile
37
Is **salmonella** acid-stable or acid-labile?
**Acid-labile**. It requires a high infectious dose to cause disease.
38
How does **Salmonella** **invade** the **GI Tract** (same as **Shigella**)?
It invades the **M-cells** of the **Peyer's Patches** in the intestines (collections of lymphoid tissue that assess for infection)
* After it moves past the intestinal wall, it travels through the **mesenteric lymph nodes** -- where it **multiplies inside macrophages**
* Macrophages are lysed and released
39
Salmonella typhi
40
High yield clinical association between **S. typhi** & **sickle cell patients**?
Development of **osteomyelitis**.
41
How would you describe the diarrhea in **S. typhi** versus **Shigella**?
S. typhi
* **Pea-soup watery** diarrhea
Shigella
* **Bloody mucoid** diarrhea (inflammatory)
42
Salmonella enteritidis
43
Shigella
44
What is the 1st line Rx for S. typhi?
**Fluoroquinolones**
2nd line
* **Azithromycin** (macrolides)
45
Which population group is most affected by **Shigella**?
**Children**
* Adults have better immunity to fight off Shigella infection
46
What is the main cause of **Shigella's pathogenicity**?
**Direct bacterial spread**.
* **Not toxin-mediated** (despite the production of Shiga toxin-- which is more important with E. coli's Shiga-like toxin)
47
Yersinia enterocolitica
48
How does **Yersinia's enterotoxin** work?
1. It actives guanylate cyclase
2. Increases **intracellular levels of cGMP**
3. Results in **watery diarrhea**
49
E. coli (overview)
50
What is one of the **unique biochemical** characteristics of **E. coli** bacteria that can be assessed in the lab?
It is **Indole (+)**. Can break tryptophan down into Indole.
* It is also **Lactose-fermenting** (& glucose-fermenting) on EMB agar (blue color)
51
Which **E. coli** virulence factor is implicated in **neonatal meningitis**?
**K1 polysaccharide capsule**
* Prevents **phagocytosis** or **complement activation**
52
Which **E. coli** virulence factor is implicated in **UTIs**?
**Pili / Fimbriae**
* Enables adhesion to the **uroepithelial surface**
53
ETEC vs. EHEC diarrhea:
ETEC
* **Watery** diarrhea
EHEC
* **Bloody** diarrhea
54
**Name that bug**: Common cause of **acute kidney failure** in otherwise healthy patients in the USA. Patient has quickly developed **bloody diarrhea** and worsened kidney function after an outdoor BBQ
**EHEC** 0157:H7
* Hemolytic-uremic syndrome (**HUS**)
55
Clinical triad of **Hemolytic-uremic syndrome** in **EHEC**:
**Triad**
1. Hemolytic anemia
2. Thrombocytopenia
3. AKI
56
What is the major mediator of **pathogenicity** in **EHEC 0157:H7**?
**Shiga-like toxin**
* **Inactivates the 60s ribosomal subunit**
* stops protein production -- leads to cell death
* **Toxin-mediated enterocyte death** & **intestinal hemorrhage**
* (In contrast to Shigella, where toxin plays a minor role in pathogenesis)
57
**EHEC** 0157:H7
58
**ETEC**
59
**2 enterotoxins** in ETEC:
1. **LT** -- **increases cAMP** in gut mucosa (like cholera toxin)
2. **ST** -- **increases cGMP** in gut mucosa
Result = watery diarrhea
60
Gram negative rod that is both:
1. **Lactose-fermenting**
2. **Urease positive**
High clinical suspicion for **Klebsiella pneumoniae**
61
**Klebsiella pneumoniae** commonly causes which **type** of **pneumonia**?
**Aspiration pneumonia** (usually lobar).
* Elderly
* Alcoholics
* Diabetics
62
Which gram negative bacteria can lead to to struvite kidney stones?
Klebsiella pneumoniae
63
Klebsiella pneumoniae
64
All gram-negative curved rods have what biochemical trait?
They are oxidase-positive.
65
Which gram negative corkscrew-shaped rod bacteria grows specificlaly at 42 degrees celsius?
Campylobacter jejuni
66
Campylobacter jejuni
67
Vibrio (Cholera)
68
Helicobacter Pylori
69
Borrelia burgdoferi (**Lyme**)
70
Leptospira Interrogans
71
What gram negative **spirochete infection** are people who do a lot of **water sports** most susceptible to?
## Footnote
Hint: presents with conjunctival suffusion, liver failure, and renal failure
Leptospirosis
72
**Name that syndrome**: Patient exhibits **ascending muscle weakness** after having **bloody diarrhea**
**Guillain-Barre** syndrome after **C. Jejuni** infection
73
**Name that bug**: Patient exhibits **unilateral arthritis** of the knee, **conjunctivitis**, & **urethritis**
**Campylobacter jejuni**
Reactive arthritis triad
1. **Unilateral arthritis** of large joints (knee)
2. **Conjunctivitis**
3. **Urethritis**
74
**Biochemical profile** of *Vibrio cholerae*:
1. **Oxidase (+)**
2. **Alkaline media** (TCBS agar growth)
3. **Motile** - flagella
4. **Gram-negative comma shaped** rod
75
Ingestion of contaminated **shellfish** in the USA can result in which **gram-negative comma shaped rod** infection?
Vibrio cholerae
76
Diarrhea description for **Vibrio cholerae**:
**Rice-water** diarrhea
77
**Name that bug**: Patient who lives in New England is exhibiting **heart (AV) block)**, **facial dropping**, and **migratory joint pains**
**Borrelia burdgorferi** (Lyme disease)
Rx = **Doxycycline**
78
**Treponema pallidum** (overview - part 1)
79
**Treponema pallidum** (overview - part 2)
80
**Treponema pallidum** (Dx)
81
Congenital Syphilis
82
**Chlamydia** (overview)
83
Which **form** of chlamydia is **infectious**: **elementary body** or **reticular body**?
**Elementary body**.
1. Elementary body -- extracellular infectious form
2. Reticular body -- intracellular replicating form (large inclusion body) that releases elementary bodies
84
**Name that organism**: "Can't see, can't pee, can't climb a tree"
Chlamydia trachomatis
85
Chlamydia trachomatis
86
*Chlamydia pneumoniae* **vs.** *psittaci*
87
**Rx** for *Chlamydia pneumoniae* **vs.** *psittaci*
## Footnote
The Psittaci parrot loves Doxy.
**C. pneumoniae** -- Azithromyrin (macrolides)
**C. psittaci** -- Doxycycline
88
Rickettsia rickettsii
89
Direction of **rash spread** in the *Rickettsia* family: **rickettsii** vs. **typhi & prowazekii**
**Rickettsii** in **Rocky Mountain Spotted Fever**
* Centripetal behavior
* Starts at the palms & soles / wrists & ankles -- then moves inward to the trunk
**Typhi & Prowazekii**
* Rash on the trunk (centrally) that spreads outward, and spares the palms and soles
90
Rickettsia **typhi** vs. **prowazekii**
## Footnote
The poacher has body lice & the tiger has (rat) fleas.
91
**Anaplasma** vs. **Ehrlichia** (overview)
92
What **clinical presentation** can help you distinguish between **Anaplasma** (ixodes tick) & **Ehrlichia** (lone star tick), as they both cause non-specific flu-like illness?
**Ehrlichia** causes a **rash**, whereas Anaplasma doesn't.
93
**Anaplasma** vs. **Ehrlichia**: vector & infected cell types
Anaplasma
* **Ixodes tick**
* Infects **PMN**
Ehrlichia
* **Lone Star tick**
* infects monocytes (**macrophages**)
## Footnote
Both show mulberry-like inclusions in cytoplasm.
94
Coxiella burnetii (Q fever)
