Gram Negatives II

Question 1

What are the characteristics of Pseudomonas aeruginosa?

Answer 1

G- rod

Motile with flagella

Oxidase positive

Green fluorescent pigment pyoverdin

Question 2

What are the Pseudomonas toxins?

Answer 2

Endotoxin (LPS) - fever, shock

Exotoxin A - inactivate elongation factor EF-2, necessary for protein synthesis

Question 3

What are common Psuedomonas infections?

Answer 3

Pnemonia in CF

Burn infections

Hot tub folliculitis

Otitis externa (swimmer’s ear)

Osteomyelitis in IV drug users (classic case)

Ecthyma gangrenosum - black, necrotic ulcers

Question 4

What is Pseuomonas folliculits?

Answer 4

Results form immersion in contaminated water

Secondary infection in people have acne or depilate their legs

Question 5

What is the treatment for Pseudomonas?

Answer 5

Resistant to many antibiotics, treatment must be tailored

Combination: Anti-Pseudomonas penicillin plus an aminoglycoside

Question 6

Why has multidrug resistance become a major issue with management of nosocomial P. aeruginosa infections?

Answer 6

Acquisition and accumulation of:

Chromosomal B-lactamases

Extended-spectrum B-lactamases (ESBL)

Porin channel mutations

Efflux pumps

Question 7

What is Burkholderia cepacia?

Answer 7

G- rod

Oxidase and Catalase positive

Rare cause of two infections: CF, Chronic gramulotmatous disease

Question 8

What is Legionella?

Answer 8

Doesn’t gram stain, use silver stain

BCYE agar, Fe and cyteine needed

Question 9

What are the symptoms of Legionella infection?

Answer 9

Initially milde pneumonia symptoms - Fever, mild, slightly productive cough

GI - watery diarrhea, nausea, vomiting and abdominal pain

Hyponatremia

Question 10

What is the classic presentation for Legionella?

Answer 10

Mild cough, Water diarrhea, confusion, G-

Treatment: Fluoroquinolone, Macrolide

Question 11

What is Pontiac Fever?

Answer 11

Mild form of Legionella infection

Fever, malaise, chills, fatigue, headache

No respiratory complaints

Question 12

What is Bacteroides fragilis?

Answer 12

G- rod

Most common bacteria in GI flora

Part of polymicrobial infections from GI tract

Treated with metronidazole

Question 13

What is Acinetobacter?

Answer 13

Aerobic, G- bacteria that are widely distributed

Often multidrug resistant, occasionally cause nosocomial infection

Question 14

What is Moraxella catarrhalis?

Answer 14

G- diplococci

Causes otitis media, COPD exacerbations

Usually treated empirically

Question 15

What are some characteristics of Neisseria?

Answer 15

Cause meningitidis and Gonorrhea

G- cocci

Glucose fermenters

Ceftriaxone used to treat

Question 16

What is the difference between N. meningococcus and N gonococcus?

Answer 16

N. meningococcus ferments maltose

Gonoccous only ferments glucose

Question 17

What is the major virulence factor for Neisseria?

Answer 17

Polysaccharide capsule, basis for serotyping

Question 18

What is the pathogenesis of meningococcus?

Answer 18

Adhere to nonciliated columnar epithelial and induce endocytosis

Avoids intracellular death and migrates to subepithelial space

May seed meninges and cause meningitis

Question 19

What patients are at an increased risk for meningococcus infection?

Answer 19

Patients with late complement deficiencies (C5-C9)

Question 20

What are the complications of bacteremia in N. meningitidis infection?

Answer 20

Spesis, fevers, chills, tachycardia

Pupuric rash

DIC

Question 21

What is Waterhouse-Friderischsen syndrome?

Answer 21

Adrenal destruction from meningococcemia

Question 22

What causes outbreaks in dorms/barracks and can infect young, healthy people?

Answer 22

N. meningitidis via respiratory droplets

Question 23

What is the prophylaxis for N. meningitidis?

Answer 23

Rifampin

Ceftrixone or Ciprofloxacin

Question 24

Describe N. meningitides vaccines?

Answer 24

Quadra-valent for group specific capsular polysaccharides

Does not cover sserotype B

Two vaccines:

MPSV4 - polysaccharide

MCV4 - conjugate to diptheria toxoid protein carrier

Question 25

What are the characteristics of N. gonorrhea?

Answer 25

Mainly causes gonorrhea

Grown on Thayer-Martin agar

Key feature: antigenic variation of pilus proteins - no long term immunity, re-infection, no vaccine

Question 26

What does N. gonorrhea co-infect with?

Answer 26

Chlamydia

Both cause same symptoms

Question 27

What are the male and female symptoms of Gonorrhea?

Answer 27

Men: urethritis, dysuria, discharge. Can progress to epididymitits/orchitis

Women: Itching, discharge from cervix. Not painful, Can progress to PID

Question 28

What is Pelvic Inflammatory Disease?

Answer 28

Infection by N. gonorrhea

Causes Pelvic/abdominal pain, dyspareunia, cervical motion tenderness (chandelier sign)

Question 29

What is Fits-Hugh-Curtis Syndrome?

Answer 29

Infection by N. gonorrhea

Perihepatitis, inflammation of Glisson’s capsule around liver

Severe RUQ tenderness with pleuritic pain

Violin strain adesions of parietal peritoneum to liver

Question 30

What is Bordetella Pertussis?

Answer 30

G- coccobacillus

Aerobic, oxidase and catalase +

Hallmark is lymphocytosis which prevents lymphocytes from entering lymph nodes

Grown on Bordet-Gengou media

Transmitted by aerosolized droplets

Question 31

What are the symptoms of B. pertussis infection?

Answer 31

Recurrent, violent cough that can last up to 6 weeks

Capable of invading the respiratory trat causing pertussis or whooping cough

Question 32

What is Pertussis toxin?

Answer 32

Shot to inhibit Gi protein

Increased cAMP levels in neutrophils

Causes impaired recruitment of neutrophils

May not cause cough

Question 33

What is the vaccine for pertussis?

Answer 33

Administered in combination with toxoids of diphtheria and tetanus (DTaP)

Administration of doses at 2, 4, 6, and 15-18 months

Booster at 4-6 years

Question 34

What is the treatment for B. pertussis?

Answer 34

Susceptible to several drugs

Main drug is erythromycin