Intro to Aerobic Gram-Neg Bacteria

Question 1

Gram-negative vs Gram-positive

Answer 1

Gram positive has THICKER peptidoglycan layer. But Negative has periplasmic space!

Question 2

2 Main differences between Staphylococci and Streptococci?

Answer 2

Catalase: + for Staph, - for Strep.
Arrangements: Clumps for Staph, Chains for Strep

Question 3

Escherichia Coli (E. Coli)

Answer 3

• Cause:Urinary Tract Infections, Bacteremia, Diarrhea, Neonatal Sepsis and Meningitis.
• 2 Main strains… ETEC, and EHEC/STEC

Question 4

E. Coli: ETEC

Answer 4

• Needs a LOT of cells to transmit.

- Produce enterotoxins which cause watery diarrhea(not bloody, bloody would require a toxin which causes cell death)

Question 5

E.Coli: EHEC/STEC

Answer 5

• Hamburger disease(also vegetables!)
• Requires little cells to infect!
• Produce Shiga Toxin… halts protein synthesis and causes cell death
• Causes bloody diarrhea and severe abdominal cramping
• Don’t use antibiotics!!!

Question 6

Klebsiella Pneumoniae

Answer 6

-Urinary tract infections, liver abscess syndrome(polysaccharides protect it from immune system), Pneumonia

Question 7

Pseudomonas Aeruginosa

Answer 7

• Isolated from green pus
• Gram-neg bacillus
• Oxidase + (grape like
• Causes Ventilator and hospital associated pneumonia, Urinary Tract Infection, Bacteremia, Folliculitis, Otitis external, Surgical site/burn infections
• Resistant to LARGE number of antibiotics!

Question 8

Neisseria Meningitidis

Answer 8

-Gram-neg diplococci
Causes meningitis and meningococcemia
-Those at risk are complement deficient
-Diagnosis: Blood culture and CSF cell count, gram stain, and culture! Meningitis would have LOW glucose (bacteria eating it all!), and HIGH protein (bacteria contain proteins), and HIGH WBC! Mainly neutrophils! ALSO Gram-neg diplococci in CSF is basically diagnostic!
-Structure: Capsule! Opacity protein, Pilus which allows attachment, LOS causing sepsis, Human Factor H-binding protein
-Sudden onset, fever, headache, photophobia, nausea, vomiting, stiff neck, myalgia, inflamed meninges, rash
-Late signs: Delirium, unconsciousness, seizures
- Treat with Dexamethasone, ceftriaxone, vancomycin, ampicillin, or penicillin G or ampicillin
-Common Pathogens: S. Pneumoniae, N. Meningitidis, H Influenzae
-12 zero groups
-You can immunize, and use antibiotics to prevent

Question 9

Haemophilus Influenzae

Answer 9

Gram neg, coccobacillus

-Causes Bacteremia, meningitis, pneumonia, epiglottitis, sinusitis, otitis media

Question 10

Moraxella Catarrhalis

Answer 10

Ox. Positive, Gram neg.

-Otitis media, chronic obstructive pulmonary disease exacerbations

Question 11

Neisseria Gonorrhoeae

Answer 11

Incubation period is 2-7 days
Gram neg, Oxidase +
Males: Symptomatic… urethritis, epididymitis
Females: Asymptomatic… Cervicitis, pelvic inflammatory disease, urethritis
Males and Females:
Pharyngitis, conjunctivitis, disseminated gonococcal infection.
Prevent with Condoms/barriers

Question 12

Classifications of Gram Neg Bacteria

Answer 12

Bacili - Glucose fermenting(lactose fermenting/nonfermenting)/non fermenting.
Cocci
Coccobacilli