Gram Negative Rods

What structural feature do all gram-negative rods share?

An outer membrane containing lipopolysaccharide (endotoxin)

What is the medical importance of endotoxin (LPS)?

Triggers inflammation, fever, and septic shock

Are Pseudomonas species oxidase positive or negative?

Oxidase positive

What type of flagella does Pseudomonas have?

Monotrichous

Why is Pseudomonas aeruginosa dangerous in hospitals?

Resistant to disinfectants, antibiotics, and forms biofilms

What enzyme breaks hydrogen peroxide into water and oxygen?

Catalase

Where does Legionella pneumophila commonly live?

Water systems and inside amoebas

What disease does Legionella cause?

Legionnaires’ disease

What antibiotic treats Legionnaires’ disease?

Azithromycin

What infections are Enterobacteriaceae most associated with?

Diarrhea and nosocomial infections

What does the IMViC test identify?

Coliforms within Enterobacteriaceae

What does a positive indole test indicate?

Tryptophan degradation to indole

What does a positive methyl red test indicate?

Acidic glucose fermentation

What does a positive citrate test indicate?

Ability to use citrate as a carbon source

Which E. coli strain causes hemorrhagic colitis?

E. coli O157:H7

What toxin does EHEC produce?

Shiga-like toxin

Which E. coli causes traveler’s diarrhea?

Enterotoxigenic E. coli (ETEC)

How does Salmonella enter epithelial cells?

Trigger mechanism using actin rearrangement

What disease does Salmonella typhi cause?

Typhoid fever

Where are chronic carriers of S. typhi colonized?

Gallbladder

What vector transmits plague?

Fleas

What are the three forms of plague?

Bubonic, septicemic, pneumonic

Why do fleas become ravenous when infected?

Coagulase causes blood clots blocking the esophagus