Gram Negative Opportunistic Pathogens

Question 1

what is an opportunistic infection

Answer 1

infections that only cause disease in compromised peope

• immunocompromised
• physical barrier breaches
• alterations in innate protective mechanisms

Question 2

where are Gm-OP found?

Answer 2

numerous environements and survive in diverse conditions

Question 3

LPS contributes symptoms of infections

Answer 3

ok

Question 4

why are opportunistic infections increasing?

Answer 4

increased scope of surgical treatments, implants, and transplants

increased indwelling devices

increased capacity to sustain chronically ill

increased interventions that cause immunosuppression

immunosuppression from primary infection

Question 5

OPs cause pneumonia. what factors contribute?

Answer 5

lung/heart/CNS/ or cancer diseases

surgery (in elderly and procedures that prevent coughing)

mechanical ventilation

lying flat

sedation

Question 6

nosocomial infeciton

Answer 6

infection occurs in hospital

Question 7

biofilms

Answer 7

dense microbial communities surrounded by ECMs

associated w/ implants and catheter infections

Question 8

what is the most common OP and what does it cause?

Answer 8

E coli

1 GI
2 UTI
3 bacteremia
4 meningitis

Question 9

uropathogenic E coli symptoms

Answer 9

UPEC

cause 95% of hospital acquired UTIs. women more suceptible

cystitis (bladder)- dysuria (burning), frequency, urgency, suprapubic tenderness

pylenophritis- UTI in the kidney- flank pain, tenderness/fever, dysuria, frequency, urgency

Question 10

UPEC adhesins/disease

Answer 10

pilli or fimbrae

pili/fimbriae
-P pili (MR) Pyelonephritis/cystitis

• Prs pili (MR) Cystitis
• Type 1 pili (MS) Cystitis
• S pili (MR) Cystitis

nonfimbrial adhesin
-F adhesin (MR) Pyelonephritis

-Dr adhesin (MR) Cystitis

MR = mannose resistant
MS = mannose sensitivity

Question 11

what is a common cause of UTI?

Answer 11

catheter use

Question 12

not all humans are equivalent in terms of disease susceptibility

Answer 12

characteristics of your blood group (ex. globoseries Gal-Gal constituent) affect which cells bacteria can adhere to

Question 13

e coli bacteremia

Answer 13

leading cause of nosocomial bacteremia is e coli

common routes are UTIs or indwelling medical devices (unknown how)

has resistance related to k1 capsule

causes systemic rxn to LPS/endotoxin

Question 14

neonatal meningitis

Answer 14

caused by e coli K1

unknown how it gets to CNS, but capsule is important

proliferation in CSF is important, siderophores in particular cause damage

Question 15

pseudomonas aeruginosa infections

Answer 15

burns, catheters, implanted devices, ventilator pneumonia, eyes, bacteremia

chronic indections- occur in lung w/ diseases like COPD or CF

Question 16

P. aeruginosa toxins

Answer 16

endotoxin

exotoxins- proteases, elastases, phospholipases

some secreted by T3SS

Question 17

pyocyanin

Answer 17

P aeruginosa produces blue/green pigment- toxic ROS

Question 18

P. aeruginosa cannot ferment sugars. considered obligate aerobe

Answer 18

ok

Question 19

clinical syndromes of klebsiella pneumoniae

Answer 19

pneumonia w/ underlying medical problems (alcoholism)
- causes red jelly sputum

UTI

wounds

bactermia/meningitis

diarrhea

Question 20

most important klebsiella pneumoniae virulence factor

Answer 20

main virulence factor is capsule

Question 21

enterobacter cloacae

Answer 21

associated w/ burn, wound, UTI, repiratory

infection occurs secondary to antibiotic therapy

lactose fermenter

Question 22

serratia marcesens

Answer 22

prodigiosins produce red color

infections secondary to antibiotic therpy

forms biofilms

infections are respiratory and UTI, GI in neonates

associated w/ heroin addicts or septic arthritis outside hospital

Question 23

serratia marcesens virulence factors

Answer 23

fimbrae, proteases, siderophores, swarming motility

Question 24

proteus vulgaris, proteus mirabilis

Answer 24

UTIs

flagella (swarming motility) and urease synthesis (break down ura to increase pH and causing stone formation) are two pathogenic mechanisms

Question 25

acinetobacter

Answer 25

oxidase nonfermenter, short rod

associated w/ indwelling medical devices

most intrinically antibiotic resistant bug

Question 26

diagnosis of OP

Answer 26

colony morphology- shape, color, smell

selective medium

biochemical tests (fermenter, gas production, urease, oxidase)