Micro - Clinical Bacteriology (Gram - Rods & Comma-Shaped)

Question 1

What are the main 2 conditions caused by Legionella pneumophila? What are the signs/symptoms associated with each condition?

Answer 1

(1) Legionnaires’ disease = severe pneumonia, fever, GI, and CNS symptoms (2) Pontiac fever = mild flu-like syndrome

Question 2

What bacteria causes Legionnaires’ disease? What are the symptoms of Legionnaires’ disease?

Answer 2

Legionella pneumophila; Severe pneumonia, fever, GI, and CNS symptoms

Question 3

What bacteria causes Pontiac fever? What are the symptoms of Pontiac fever?

Answer 3

Legionella pneumophila; Mild flu-like syndrome

Question 4

What kind of bacteria is Legionella pneumophila?

Answer 4

Gram-negative rod

Question 5

What is important to know about the staining of Legionella pneumophila?

Answer 5

Gram stains poorly (negative) - use silver stain

Question 6

On what type of media does Legionella pneumophila grow?

Answer 6

Grow on charcoal yeast extract culture with iron and cysteine

Question 7

How is Legionella pneumophila detected clinically?

Answer 7

Presence of antigen in urine

Question 8

How is Legionella pneumophila transmitted, and from where? How is it not transmitted?

Answer 8

Aerosol transmission from environmental water source habitat; No person-to-person transmission

Question 9

What is the treatment for Legionella pneumophila?

Answer 9

Macrolide or quinolone

Question 10

What lab finding (chem-7) is in patients with Legionella pneumophila?

Answer 10

Hyponatremia

Question 11

With what kind of infections is Pseudomonas aeruginosa associated?

Answer 11

Wound and burn infections

Question 12

What 7 conditions does Pseudomonas aeruginosa cause?

Answer 12

(1) Pneumonia (espcially in cystic fibrosis) (2) Sepsis (black lesions on skin) (3) External otitis (swimmer’s ears) (4) UTI (5) Drug and DiabetesOsteomyelitis… plus hot tub folliculitis; (6) Malignant otitis externa in diabetics. (7) Ecthyma gangrenosum—rapidly progressive, necrotic cutaneous lesions caused by Pseudomonas bacteremia. Think: “PSEUDOmonas (plus just remember hot tub folliculitis)”

Question 13

What kind of bacteria are Pseudomonas aeruginosa? Think in terms of both metabolic and gram-stain classifications.

Answer 13

Aerobic, non-lactose fermenting, oxidase positive, gram-negative rod

Question 14

What kind of pigment and odor do Pseudomonas aeruginosa make?

Answer 14

Pyocyanin (blue-green) pigment; grape-like odor

Question 15

What condition(s) can Pseudomonas aeruginosa cause in diabetics?

Answer 15

Diabetic osteomyelitis & malignant otitis externa

Question 16

What is often a source of Pseudomonas aeruginosa?

Answer 16

Water

Question 17

What toxins do Pseudomonas aeruginosa make, and what are their effects?

Answer 17

(1) Endotoxin (fever, shock) (2) Exotoxin A (inactivates EF-2)

Question 18

How is Pseudomonas aeruginosa treated?

Answer 18

Beta-lactam (e.g., piperacillin, ticarcillin, cefepime, imipenem, meropenem) +/- aminoglycoside. Ciprofloxacin if UTI.

Question 19

What effect does Pseudomonas aeruginosa commonly have on cystic fibrosis patients, and with what is this effect associated?

Answer 19

Chronic pneumonia, associated with biofilm

Question 20

What are the E. coli virulence factors? With what conditions/diseases is each associated?

Answer 20

(1) Fimbriae - cystitis and pyelonephritis (2) K capsule - pneumonia, neonatal meningitis (3) LPS endotoxin - septic shock

Question 21

What are the strains of E. coli?

Answer 21

(1) EIEC (Enteroinvasive) (2) ETEC (Enterotoxigenic) (3) EPEC (Enteropathogenic) (4) EHEC (Enterohemorrhagic)

Question 22

What is the mechanism of EIEC? What is its presentation?

Answer 22

Microbe invades intestinal mucosa & causes necrosis & inflammation; Clinical manifestations similar to Shigella; Invasive, dysentery; Think: “I is for Invasive”

Question 23

To what other bacteria does EIEC present similarly?

Answer 23

Shigella

Question 24

What is the toxin/mechanism of ETEC? What is its presentation?

Answer 24

Labile toxin/stable toxin. No inflammation or invasion; Traveler’s diarrhea (watery); Think: “T is for Traveler’s diarrhea”

Question 25

What is the toxin/mechanism of EPEC? What is its presentation?

Answer 25

No toxin produced. Adheres to apical surface, flattens villi, prevents absorption; Diarrhea usually in children (Pediatrics); "Think: P is for Pediatrics"

Question 26

What is the toxin/mechanism of EHEC? What is its presentation?

Answer 26

Shiga-like toxin cause hemolytic-uremic syndrome (triad of anemia, thrombocytopenia, and acute renal failure); Microthrombi form on endothelium damaged by toxin => mechanical hemolysis (schistocytes formed) and decreased renal blood flow; microthrombi consume platelets => thrombocytopenia. Dysentery (toxin alone causes necrosis and inflammation); Think: "H is for Hemolytic-uremic syndrome"

Question 27

What distinguishes EHEC from other E. Coli?

Answer 27

Does not ferment sorbitol

Question 28

What syndrome is caused by EHEC? With what symptoms is it associated?

Answer 28

Hemolytic-uremic syndrome; Triad of anemia, thrombocytopenia, & acute renal failure

Question 29

What is the most common serotype of EHEC?

Answer 29

O157:H7

Question 30

Where is Klebsiella normally found?

Answer 30

Intestinal flora

Question 31

How do Klebsiella colonies appear, and why?

Answer 31

Very mucoid colonies caused by abundant polysaccharide capsule

Question 32

What is a clinically relevant sign of Klebsiella?

Answer 32

Red "currant jelly" sputum

Question 33

What major disease does Klebisella cause, in what populations, and under what circumstances?

Answer 33

Causes lobar pneumonia in alcoholics and diabetics when aspirated; Think: "4 A's: (1) Aspiration pneumonia (2) Abscess in lungs and liver (3) Alcoholics (4) di-A-betics"

Question 34

Besides lobar pneumonia in alcoholics and diabetics, what other category of disease/condition is associated with Klebsiella?

Answer 34

Also cause of nosocomial UTIs

Question 35

Compare/Contrast Salmonella and Shigella in terms of motility.

Answer 35

SALMONELLA - have flagella; SHIGELLA - no flagella; Think: "SALMONella swim"

Question 36

What is the method of dissemination (once inside the body) for Salmonella versus Shigella?

Answer 36

SALMONELLA - can disseminate hematogenously; SHIGELLA - cell to cell transmission, no hematogenous spread

Question 37

What is the reservoir for Salmonella versus Shigella?

Answer 37

SALMONELLA - have many animal reservoirs ; SHIGELLA - only reservoirs are humans and primates

Question 38

Do Salmonella and/or Shigella produce hydrogen sulfide?

Answer 38

SALMONELLA - Produce hydrogen sulfide; SHIGELLA - NOT produce hydrogen sulfide

Question 39

What effects do antibiotics have on Salmonella versus Shigella?

Answer 39

SALMONELLA - Antibiotics may prolong fecal excretion of organism; SHIGELLA - Antibiotics shorten the duration of fecal excretion of organism

Question 40

What is the response caused by Salmonella versus Shigella upon affecting the human body?

Answer 40

SALMONELLA - Invades intestinal mucosa & causes a monocytic response; SHIGELLA - Invades intestinal mucosa & causes PMN infiltration

Question 41

Compare/Contrast the possibility/likelihood of Salmonella versus Shigella causing blood diarrhea.

Answer 41

SALMONELLA - can cause bloody diarrhea; SHIGELLA - OFTEN causes bloody diarrhea

Question 42

Do Salmonella and/or Shigella ferment lactose?

Answer 42

Neither ferments lactose

Question 43

What causes typhoid fever? What characterizes it?

Answer 43

Salmonella typhi; Rose spots on abdomen, fever, headache, and diarrhea

Question 44

In what reservoir is Salmonella typhi found?

Answer 44

Only in humans

Question 45

What is important to know about the potential for latency/dormancy in Salmonella typhi infections?

Answer 45

Can remain in gallbladder and cause a carrier state

Question 46

Of what condition is Camplyobacter jejuni a major cause, and in what population?

Answer 46

Major cause of bloody diarrhea, especially in children

Question 47

How is Campylobacter jejuni transmitted?

Answer 47

Fecal-oral transmission through foods such as poultry, meat, unpasteurized milk.

Question 48

What are important things to know about Campylobacter jejuni in order to classify/identify it?

Answer 48

Gram-negative, comma or S-shaped, oxidase positive, grows at 42C

Question 49

To what conditions is Campylobacter jejuni a common antecedent?

Answer 49

(1) Guillian-Barre syndrome (2) Reactive arthritis

Question 50

What are important things to know about Vibrio cholerae in order to classify/identify it?

Answer 50

Gram-negative, comma shaped, oxidase positive, grows in alkaline media

Question 51

In general, where is Vibrio cholerae endemic?

Answer 51

Developing countries

Question 52

What major symptom does Vibrio cholerae produce, and how?

Answer 52

Produces profuse rise-water diarrhea, via Toxin that permanently activates Gs, increasing cAMP

Question 53

What is the necessary response to Vibrio cholerae infection?

Answer 53

Prompt oral rehydration is necessary

Question 54

How is Yersinia entercolitica usually transmitted?

Answer 54

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

Question 55

What condition does Yersinia enterocolitica cause? What other condition(s) does this condition mimic?

Answer 55

Causes mesenteric adenitis, that can mimic Crohn's or appendicitis

Question 56

What condition(s) does Helicobacter pylori cause?

Answer 56

Helicobacter pylori - causes gastritis and peptic ulcers (especially duodenal)

Question 57

For what 3 condition(s) is Helicobacter pylori a risk factor?

Answer 57

(1) Peptic ulcer (2) Gastric adenocarcinoma (3) Gastric Lymphoma

Question 58

What are the gram stain, morphology, and metabolic characteristics of Helicobacter pylori? Which of these is most clinically relevant, and why?

Answer 58

Curved gram-negative rod that is catalase, oxidase, and urease (+) (can use urea breath test or fecal antigen test for diagnosis)

Question 59

What kind of environment does Helicobacter pylori create?

Answer 59

Creates alkaline environment

Question 60

What is the most common initial treatment for Helicobacter pylori?

Answer 60

Triple therapy: (1) Proton pump inhibitor (2) Clarithromycin (3) Amoxicillin or Metronidazole

Question 61

What bacteria causes ecthyma gangrenosum? What characterizes it? In what patient population is it seen?

Answer 61

Ecthyma gangrenosum—rapidly progressive, necrotic cutaneous lesions caused by Pseudomonas bacteremia.

Question 62

What is another name for EHEC bacteria?

Answer 62

Enterohemorrhagic E. coli (EHEC) = Also called STEC (Shiga toxin-producing E. coli)

Question 63

How is H. pylori diagnosed?

Answer 63

Can use urea breath test or fecal antigen test for diagnosis