Gram Negatives

Question 1

makeup of outside of gram negatives

Answer 1

• two cell membranes with thin peptidogylcan wall inbetween

- surface protein lipopolysaccharide

Question 2

Newer drugs are incorporating what into them?

Answer 2

• beta lactamase inhibitors to stop the bacteria from breaking it down with their beta-lactamase properties

Question 3

Pathogenic features of Gram Negatives

Answer 3

• Infections
• Endotoxins- lipopolysaccharide
• Enterotoxins - E. coli, shigella, infections diarrhea
• community and nosocomial acqusitions
• intrinsic resistance mechanisms exist in some species like beta-lactamase, efflux pumps, outer membrane

Question 4

____ has many gram (-)s which are fine unless they leave this area

Answer 4

• GI tract

Question 5

Medically Relevant Gram Negative bacteria

Answer 5

• gram neg bacilli (enterobacteraceae and non-enterobacteriaceae)
• gram neg cocci/ coccobacilli
• “Other” gram neg bacteria
• Gram neg anaerobes

Question 6

Enterobacteriaceae

Answer 6

• diverse bacterial group -thousands of species: found in normal GI flora!
• Enteric gram negative bacilli
• e. coli
• enterbacter spp.
• citrobacter spp.
• salmonella, shigella, camplyobacter
• Primary cause of clinically significant gram neg infections
• food/water borne pathogens
• e. coli
• shigella
• salmonella
• campylobacter
• vibrio cholerae

Question 7

SPACE

Answer 7

• highly drug resistant enteribacteriaceae

- cause GI infections

Question 8

E. coli

Answer 8

• most common shiga-toxin producing e. coli
• source; contaminated beef, and veggies
• low inoculum <100 cells needed for infection
• > 110,000 cases, 80 deaths/yr

Question 9

Enterobacteriaceae threat by CDC yes/no

Answer 9

yes

Question 10

Non-enterobacteracaea

Answer 10

• non-fermentative, gram-neg bacilli (rods)
• Organisms:
• pseudomonas aeruginosa
• acinterobacter baumanii
• stenotrophomonas maltophilia
• berkholderia cepacia
• not normal flora
• nosocomial infections
• multi-drug resistant infections

Question 11

Pseudomonas Aeruginosa

Answer 11

• normally colonizes soil, water, plants
• cause of both chronic and acute disease
• infections:
• SSTI/foliculitis
• endocarditis
• sepsis
• post-op wounds
• IV catheters

Question 12

Multi-drug resistant Pseudomonas Aeruginosa threat level

Answer 12

• threat level serious

Question 13

Acinetobaacter baumanii

Answer 13

• mostly found in hospitals in/on equiptment
• days to weeks duration
• infects immunocompromised hosts
• high crude mortality
• infections: pneumonia (vents), open wounds, lines

Question 14

Multi-drug resistant acinetobacter baumanii threat level

Answer 14

• threat level serious

Question 15

Clinical Pearls- Non-enterobaacteraceae

Answer 15

• cover for pseudomonas in suspected noscomial infection until pathogen identified
• double coverage used initially
• few treatment options for MDR pseudomonas and acinetobacter
• Stenotrophomonas treatment of choice: TMP/SMX
• WASH HANDS

Question 16

Gram negative cocci/ coccobacilli

Answer 16

• Haemophilus spp
• h. influenzae
• Moraxella catarrhalis
• OM, sinusitis, bronchitis, pneumonia
• Neisseria spp
• N. menigitidis (meningitis)
• N. gonorrhea

Question 17

Haemophilus influenzae

Answer 17

• gram negative cocci
• encapsulated, anaerobe
• type B most clinically significant
• colonizes upper resp tract
• infections mostly children: CAP, Meningitis, SInusitics, OM, Conjunctivitis
• antibiotic resistance variable

Question 18

Nisseria Meningitidis

Answer 18

• gram negative diplococcus
• carried in nasopharyngeal secretions
• requires culture from sterile body fluid like blood, CSF for diagnosis
• produces polysaccharide capsule
• cause of meningitis and associated sequelae
• BETA-LACTAMS best therapy!!

Question 19

Neisseria Gonnorrheae

Answer 19

• gram neg cocci
• second most common reportable disease in US
• sexually transmitted
• reinfection in >40% of high risk patients within one year treatment

Question 20

Drug Resistant Neisseria Gonorrheae threat level

Answer 20

• threat level Urgent!

Question 21

Chlamydia trachomatis

Answer 21

• number 1 bacterial STD in US
• about 50% of men have symptoms
• 75% of women are asymptomatic and can transfer disease without knowing

Question 22

other gram neg pathogens

Answer 22

• helicobacter pylori
• brucella
• francisella tularensis
• yersinia pestis (plague)
• bordetella pertussis (whooping cough)
• legionella (legionare’s disease)

Question 23

Gram negative anerobes

Answer 23

• distinguished as “true anaerobes” and metronidazole susceptible, gram (-) rods
• bacteroides fragilis (most common and pathogenic) lower GI, abdominal abscesses
• fusobacterium (mouth upper resp, lemierre’s disease acute jugular vein septic thrombopheblitis)
• prevotella spp (mouth, upper resp, lower resp)