Gram negative bacteria

Question 1

Gram (-), oxidase positive, comma shaped

Answer 1

Campylobacter jejuni, grows at 42 C and Vibrio cholerae, grows in alkaline media

Question 2

Gram - rods that are lactose fermenters

Answer 2

Klebsiella and E Coli

Question 3

gram - rod, lactose nonfermenter, and oxidase -

Answer 3

shigella, salmonella, and proteus

Question 4

gram - rod, lactose nonfermenter, and oxidase +

Answer 4

Pseudomonas and H pylori

Question 5

Gram - diplococci

Answer 5

Maltose nonfermenter = N. gonorrhoeae and Maltose fermenter = N. meningitidis

Question 6

N. Gonorrhoeae

Answer 6

Gram negative diplocci. Ferments glucose and IgA protease. No polysaccharide capsule. No maltose fermentation. No vaccine (pili antigenic variation). Sexual transmission. Causes gonorrhea, septic arthritis, neonatal conjuntivitis, PID, and FHC syndrome. TX = Ceftriaxone + (azithromycin or doxycycline) for possible chlamydia infection

Question 7

N. Meningitidis

Answer 7

Produce IgA protease and ferments glucose. Ferments maltose and glucose. Has a polysaccharide capsule. Has vaccine. Transmit by respiratory and oral secretions. Causes meningitis and Waterhouse- Friderichsen syndrome. In close contacts = rifampin, ciprofloxacin, or ceftriaxone prophylaxis in close contacts. Tx= ceftriaxone or penicillin G

Question 8

Haemophilus influenzae

Answer 8

haEMOPhilus. Causes Epiglottis, Meningitis, Otitis media, and Pneumonia. Gram negative rod. Nontypeable cause mucosal infection. Produce IgA protease. Chocolate agar = requres V and X factor. Tx with ceftriaxone. Rifampin prophylaxis in close contacts. Vaccine = type B capsular polysaccharide conjugate to diphtheria toxin.

Question 9

Legionella pneumophila

Answer 9

Legionnaires disease: pneumonia, fever, GI, and CNS symptoms
Pontiac Fever: mild flu
Gram negative rod. poor gram stain so use silver stain. Grow charcoal yeast agar with iron and cysteine. Transmission by water source. Lab = hyponatremia. Tx = macrolide or quinolone.

Question 10

Pseudomonas aeruginosa

Answer 10

PSEUDOmonas. Associated with wound and burn infections. Pneumonia in cystic fibrosis, Sepsis, External otitis (swimmers ear), Uti, Drug use, and diabetic Osteomyelitis. Hot tub folliculitis. Aerobic gram negative rod, non lactose fermenting, oxidase positive. blue - green pigment, grape like odor. Endotoxin and exotoxin A (inactivates EF-2). Tx = aminoglycoside plus extended spectrum penicillin (piperacillin, ticarcillin).

Question 11

Lactose Fermenting enteric bacteria

Answer 11

Grow pink on MacConkey agar. Lactose is KEE. Test with MacConKEE’S agar. Citrobacter, Klebsiella, E. coli, Enterobacter, and Serratia. Lactose fermenters are purple. E. coli is green with sheen.

Question 12

E coli virulence factors

Answer 12

Fimbriae - cystitis and pyelonephritis. K capsule - pneumonia, neonatal meningitis. LPS endotoxin - septic shock.

Question 13

EIEC

Answer 13

Invades intestinal mucosa. No toxin. Similar to Shigella. Invasive! Bloody diarrhea.

Question 14

ETEC

Answer 14

Watery diarrhea. Has toxin. No inflammation or invasion.

Question 15

EPEC

Answer 15

Diarrhea in Pediatrics. No toxin. Adheres to villi to prevent absorption.

Question 16

EHEC

Answer 16

O157: H7 is the most common serotype. Shiga like toxin. Can cause Hemolytic uremic syndrome = triad of anemia, thrombocytopenia, and acute renal failure. Why? Endothelium swells = mechanical hemolysis and reduced renal flow. Does not ferment SORBITOL….distinguish from other E. Coli.

Question 17

Klebsiella

Answer 17

Intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated. polysaccharide capsule…Red currant jelly sputum. Can cause nosocomial UTI. The 4As: Aspiration pneumonia, Abscess in lungs and liver, Alcoholics, and diAbetics.

Question 18

Salmonella

Answer 18

Have flagella (salmon swim).  
Can spread in blood.  
Many animal reservoirs.  
Produce hydrogen sulfide.  
Invades intestinal mucosa.  
Cause bloody diarrhea.  
Does not ferment lactose.

Question 19

Shigella

Answer 19

No flagella.  
Cell to cell transmission, no hematogenous spread.  
Human reservoir.  
No hydrogen sulfide
Bloody diarrhea.  
Does not ferment lactose.

Question 20

Salmonella typhi

Answer 20

Typhoid fever. Only in humans. Rose spots on abdomen, fever, headache, and diarrhea. Can be in gallbladder to cause carrier state.

Question 21

campylobacter jejuni

Answer 21

Bloody diarrhea. Fecal oral transmission through food such as poultry, meat, and unpasteurized milk. Comma shaped, oxidase positive, grows at 42C (Campylobacter likes hot hot CAMP fire). Can cause Guillan-Barre syndrome and reactive arthritis.

Question 22

Vibrio cholerae

Answer 22

Rice water diarrhea via toxin that activates Gs to increase cAMP. Comma shaped, oxidase positive, grows in alkaline media. Oral rehydration promptly!!

Question 23

Yersinia enterocolitica

Answer 23

Pet feces, contaminated milk, or pork. Can mimic Crohn’s or appendicitis.

Question 24

Helicobacter pylori

Answer 24

Gastritiis and up to 90% of duodenal ulcers. Risk for peptic ulcer, gastric adenocarcinoma, and lymphoma. Curved gram negative rod. Urease positive (use urea breath test to dx). creates alkaline environment. Tx is triple therapy: PPI, clarithromycin, amoxicillin or metronidazole.