Infectious Disease > Gram negative rods > Flashcards

Gram negative rods Flashcards

(63 cards)

Study These Flashcards
1
Q

Most Gram negative rods resistent to

A
  • Penicillin
  • Vancomycin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Gram negative rods ABx

A
  • Ceftriaxone
  • Fluoroquinolones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Klebsiella feautes

A
  • intestinal flora
  • non-motile/capsular
  • impaired host defenses (alcoholis, sick people)
  • treatment based on susceptibility testing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Klebsiella illnesses

A

Lovar pneumonia

Lung abscesses

liver abscesses

UTI (3-4%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Klebsiella pneumonia

A
  • Lobar
  • occurs in alcoholics or diabetics (aspiration)
  • results in red “currant jelly” sputum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Klebsiella lung abscesses

A
  • usually caused by mouth anaerobes
  • Peptostreptococcus, Fusobacterium, Prevotella, Bacteroides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Klebsiella liver abscess

A

usually in patients with underlying disease or cholangitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Features of E. coli

A
  • gram neg rods with fimbriae (pili)
    • attach to surfaces (may be specialized for particular surfaces)
  • K capsule
    • K1 capsular antigen present in 75% meningitis cases (babies)
    • inhibits phagocytosis and complement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

E. coli illnesses

A
  • Watery diarrhea
  • Bloody diarrhea (dysentary)
  • UTI/pyelonephritis
    • E coli bacteremia, sepsis (rare), usually from UTI
  • Meningitis in newborns
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

E. coli diarrheal illnesses

A
  • Enteroinvasive E. coli (EIEC)
  • Enterotoxigenic E coli (ETEC)
  • Enteropathogenic E coli (EPEC)
  • EnteroHemorrhagic E coli (EHEC)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Enteroinvasive E. coli (EIEC)

A
  • Clinically similar to shigella (no toxins in this but Shigella does make a toxin of course)
  • Invades intestinal mucosa
  • Necrosis
  • Inflammation
  • Bloody diarrhea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Enterotoxigenic E coli (ETEC)

A
  • Two toxins: Labile and Stable
  • watery (traveler’s diarrhea) from contaminated food/water
  • No imflammation
  • No invasion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Enteropathogenic E coli (EPEC)

A
  • No toxin
  • No inflammation
  • Blunt villi prevent absorption
  • Diarrhea usually in children (p=pediatrics)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

EnteroHemorrhagic E coli (EHEC)

A
  • Does not ferment sorbitol (sorbitol-McConkey agar)
  • Classic serotype: E. coli 0157:H7
  • Does not invade host cells (toxin causes disease)
  • Produces Shiga-like toxin -> bloody diarrhea
    • bacteriophage encoded (lysogenic) toxin
  • Usually from undercooked beef
  • Toxin effects
    • Endothelium swells -> vessel lumens narrow
    • Deposition of fibrin/platelets in microvasculature
    • Hemolysis, inflammation
  • Feared complication is if the toxin gets into the bloodstream causing Hemolytic Uremic Syndrome (HUS)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

HUS

A
  • Hemolytic Uremic Syndrome
  • complication of 10% of EHEC cases
  • common in children
  • Triad
    • Hemolytic anemia
    • Thrombocytopenia
    • Acute renal failure (uremia)
  • HUS + fever; mental status changes = TTP (Thrombotic Thrombocytopenic purpura)
  • usually occurs 5-7 days post diarrhea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Gram negative sepsis

A
  • Fever
  • Tachycardia
  • Hypotension
  • Life-threatening
  • Driven by endotoxin (LPS; Lipid A)
  • Common scenario
    • Elderly patient
    • UTI (catheter, BPH)
    • Gram negative sepsis (+blood cultures)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Infectious causes of bloody diarrhea

7 listed

A
  • Campylobacter
  • Salmonella enterica
  • Shigella
  • Yersinia entercolitica
  • EiEC
  • Entamoeba histolytica
  • EHEC
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Infectious causes of watery diarrhea

8 listed

A
  • ETEC
  • Cholera
  • C. diff
  • C. perfringens
  • Giardia
  • Crypto
  • Rotavirus
  • Norovirus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Fecal leukocytes and RBC iindicate?

A

usually indicate invasive infection

Bloody diarrhea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Mucous and epithelial cells in stool only seen in

A

toxin-mediated disease

Watery diarrhea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Parasitic diarrhea can be Dxd by?

A

Stool ova and parasites from protozoal infections

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Causes of diarrhea that invade the mucosa

5 listed

A
  • Campylobacter
  • Salmonella enterica
  • Shigella
  • Yersinia entercolitica
  • EIEC
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Enterobacter features

A
  • Rare cause of nosocomial UTIs
  • Resistant to many antibiotics
    • ESBL
    • Resistance to most beta-lactams; penicillins, cephalosporins and aztreonam
  • Often treated with Carbapenems
    • Imipenem
    • Meropenem
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Enterobacter treatment

A

Resistant to a lot of Abx because they have ESBLs

  • Carbapenems
    • Imipenem
    • Meropenem
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Nosocomial means?
disease originating from a hospital
26
Citrobacter & Serratia
* Slow Lactose Fermenters * Gram negative rods * Not dominant pathogen for any condition * often resistant to many Abx
27
Citrobacter features
* Can be found in normal gut flora * Gram negative sepsis (with other GN bugs)
28
Features of Serratia
* GN rod * produce diistinctive red colonies (red pigment) * Catalase positive * Hospital outbreaks of UTIs; contaminated water, soap, IV solutions * Sometimes osteomyelitis in IV drug users (also Pseudomonas)
29
Slow Lactose Fermenters
Citrobacter & Serratia
30
Types of Salmonella
* Salmonella typhi * Salmonella Enterica * Salmonella Enteritidis
31
Salmonella illnesses
* Salmonella typhi -\> typhoid fever * Non-typhoid strains cause gastroenteritis (enterica, enteritidis) * NVcramps, bloody diarrhea * ingestion of contaminated meat, eggs, poultry * osteomyelitis in sickle cell patients
32
Features of Salmonella
* Flagellated, mobil, encapsulated gram negative rod * disseminate through blood * osteomelitis in sickle cell pts * Live in GI tract of mammals, birds and reptiles * produce hydrogen sulfide * triple sugar iron (TSI) test -\> media turns black * differentiates from shigella * Invades GI mucosa * The cellular response is largely monocytes
33
Typhoid fever
* caused by Salmonella typhi * Travelers to Asia, Africa, South America * Classic features * Rose spots * Faint salmon-colored macules * Trunk and abdomen * Pulse-termperature dissociation * High fever -\> slow pulse * Can remain in the gall bladder (carrier state) * endemic countries 1-4% people may be carriers * May be risk factor for carcinoma
34
Diagnosis of Salmonella
* Culture (stool, blood (typhoid))
35
Treatment of Salmonella Gastroenteritis
Gastroenteritis * Fluids/electrolytes * Abx not really helpful (only in severely ill) * has lots of resistance * Anti-peristalsis contraindicated because prolong illness
36
Treatment of Typhoid Fever
* Ceftriaxone * Fluoroquinolones * Typhoid vaccine is available * inactive variant given orally * used for high risk travelers
37
Shigella features
* non-motile (no flagella) * not normal GI flora * Commin in children * Dx: stool culture * Invades mucosal cells (M cels in Peyer's Patches) * Macropinocytosis * Induces apoptosis * Spreads from cell-to-cell * does not spread hematogenously (salmonella does) * Releases Shiga toxin * but non-toxin strains **still** cause disease * Cellular invasion **more** important mechanisms of disease * Very few bacteria are required to cause disease (few as 10) * Cellular response is largely PMNs (neutrophils)
38
Shigella treatment
* Fluids/electrolytes * Abx improve symptoms, reduce shedding in stool * can limit spread * Ceftriaxone or Ciprofloxacin
39
How to tell Salmonella vs Shigella
* Salmonella * Produces H2S so black color on triple sugar iron TSI * Mostly Monocyte response * Hematogenous spread * No antibiotics * Motile (flagella) * Shigella * No H2S * Mostly Neutrophil response * Cell-to-cell spread (Macropinocytosis) * Yes Abx (Ceftriaxone or Ciprofloxacin) * Nonmotile * Shiga toxin * Low infectious dose
40
Proteus features
* Rare cause of UTIs * "Swarm phenotype" * long flagella * facilitates urinary ascent * Bulls-eye on agar plates * Produces urease * converts urea to ammonia * Associated with Struvite Kidney Stones
41
Pseudomonas aeruginosa features
* highly-feared bacteria * serious hospital acquired infections (i.e. VAP "Ventilator Acquired Pneumonia) * Resistant to many Abx * Obligate aerobe * gram negative rod * Loves the water (commonly found in environmental water sources * Produces blue-green pigment (pyocyanin) * smooth, fluorescent green colonies on culture media * sweet grape-like odor
42
Pseudomonas aeruginosa illnesses
* Pneumonia (Nosocomial) (Cystic fibrosis) * UTIs * Surgical wound infections * Bacteremia/sepsis * Osteomyelitis (IV drug users) * Ottitis externa (swimmers ear) * Burn infections * Hot tub folliculitis
43
Pseudomonas toxins
* Endotoxin (LPS) * can cause fever, shock * Endotoxin A * Inactivates elongation factor EF-2 * EF-2 is necessary for protein synthesis
44
Pseudomonas Pneumonia
* classic pneumonia in CF pts
45
Pseudomonas
46
Hot tub folliculitis
tender itchy papules after using hot tub or spa
47
Otitis externa
* Swimmer's ear * painful ear with discharge
48
Pseudomonas Osteomyelitis
* IV drug users
49
Ecthyma gangrenosum
* Caused by Pseudomonas bacteremia * Black, necrotic ulcers on skin with bacteremia * invasion/destruction of blood vessels by bacteria * Classic case is neutropenic cancer patient with fever, chills (bacteremia) who develops black lesions on chest and back
50
Burkholderia cepacia
* Gram negative rod similar to Pseudomonas * Oxidase positive * Catalase positive * Rare cause of infections in * Cystic fibrosis * Chronic Granulomatous Disease
51
H pylori illnesses
* gastritis & ulcers * common in paitents with ulcers (majority of duodenal ulcers) * many with gastric ulcers * MALT lymphoma * mucosal associated lymphatic tissue lymphoma * B-cell cancer; usually in the stomach * Highly associated with H. pylori
52
H pylori features
* Causes gastritis and ulcers (abdominal pain) * Urease positive * hydrolyzes urea to compounds that damage epithelium * produces ammonium (alkaline) (protects from acidic environment in stomach * Protects bacteria from stomach acid * Urea breath test * patients swallow urea with isotopes (carbon-14 or Carbon-13) * detection of isotope labled carbon dioxide in exhaled breath is evidence indicating urea was split (urease is present)
53
H pylori diagnosis
* Biopsy * Urea breath test * Stool antigen
54
H pylori treatment
* Triple therapy for 7-10 days * Proton pump inhbitor (omeprazole) * Clarithromycin * Amoxicillin or Metronidazole * Test to determine eradication (failure in 20% of attempts) * breath test, stool antigen or biopsy
55
Legionella features
* Does not gram stain well * silver stains used * special culture requirements * Buffered charcoal Yeast Extract (BCYE) with Iron and Cysteine added for growth * Supplemented with antibiotics and silver dyes * Antimicrobials prevent overgrowth by competing organisms * dyes give distinctive color to Legionella
56
Legionella illneses
* Nosocomial pneumonia in Nursing homes *
57
Legionella pneumonia symptoms
* initially mild pneumonia symptoms * fever; mild, slightly productive cough * can progress to severe pneumonia * GI symptoms * NVwD, abdominal pain * Hyponatremia (Na\<130 mEq/L) common * can occur in any pneumonia but more common with Legionella Pneumonia
58
Classic case of Legionella infection
* Mild cough * Watery diarrhea * Confusion (low Na) * Negative bacteria on gram stain (poorly visualized)
59
Treatment of Legionella
* Fluoroquinolone * or * Macrolide
60
Pontiac fever
Mild form of Legionella infection * fever * malaise * chills * fatigue * headache * no respiratory complaints * Chest radiograph usually normal
61
Bacteroides fragilis
* Gneg rod anaerobic * normal GI flora * cause infection after breach of mucosal barrier
62
Bacteroides fragilis infections
* rare to cause infections by itself * Usually part of polymicrobial infections from the GI tract * peritonitis (following perforation) * Intraabdominal abscess * Lung abscess (aspiration) * E. coli/GNR and B fragilis often components together
63
Bacteroides fragilis treatment
* Covered by Metronidazole * Common GI therapy: Cipro/Flagyl * Quinolone for E. coli * Metronidazole for B. fragilis
Infectious Disease
flashcards
Decks in class (82)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions