[BIO 120.3] Q2: Gram Negative Rods - Shigella, Salmonella, Others, Vibrio, Helicobacter

E. coli

Identify: Fimbriae + Multiple Flagella + Straight Rod

Vibrio

Identify: Curved Rod + Flagellum (single)

Shigella

Identify: Slender Rod + Fimbriae + No flagella (non-motile)

Slender rods, non-motile, cocco-bacillus in young cultures

Morphology: Shigella dysenteriae

Aerobes or Facultative Anaerobes

Oxygen Requirement: Shigella dysenteriae

Glucose Fermenters, Non-lactose Fermenters

Sugar Fermentation: Shigella dysenteriae

No H2S production

H2S production: Shigella dysenteriae

Acid Producer

Acid Production: Shigella dysenteriae

Rare Gas Production

Gas Production: Shigella dysenteriae

Facultative anaerobe

Oxygen Requirement: Salmonella

Non lactose fermenter, Non sucrose fermenter

Sugar Fermentation: Salmonella

Acid Producer

Acid Production: Salmonella

Gas Producer

Gas Production: Salmonella

H2S Producer

H2S Producer: Salmonella

Aerobes

Metabolic Diversity: Vibrio cholerae

Sucrose Fermenter

Sugar Fermentation: Vibrio cholerae

Halophilic, requires 0.5 - 4.5% NaCl

Salt Requirement: Vibrio cholerae

8.5 - 9.5 (basic)

pH Requirement: Vibrio cholerae

Microaerophilic

Oxygen Requirement: Helicobacter pylori

Longer incubation of 14 days

Incubation Period: Helicobacter pylori

Oxidase and Catalase Positive

Oxidase and Catalase Reaction: H. pylori

Urease Positive

Urease Reaction: H. pylori

Intestinal tracts of humans and primates

Dysentery infects what part of what species?

Bacillary dysentery

What infection does Shigella dysenteriae cause?

Fecal-oral

Transmission: Shigella dysenteriae

Shiga toxin

What is the virulence factor of Shigella dysenteriae?

EHEC, EIEC

The Shiga toxin produced by S. dysenteriae is similar to the toxins produced by what E. coli strains?

Low infectious dose, 10^2

What is the infectious dose for Shigella dysenteriae?

10^8

What is the infectious dose for Vibrio?

10^5

What is the infectious dose for Salmonella?

Fever, Abdominal Pain, Bloody diarrhea with mucus and pus

Clinical Findings: Shigella dysenteriae

EIEC

Shigella dysenteriae has the same clinical findings as what strain of E. coli?

Oral fluid replacement, IV fluid, No anti-diarrheal drugs, Antibiotics for severe infections

Treatment: Shigella dysenteriae

TMP-SMX, CFT, AZT

What are antibiotics given to patients with severe Shigella dysenteriae infections?

TRUE

T/F: For Shigella dysenteriae patients, anti-diarrheal drugs like loperamide are not given

FALSE

T/F: For Salmonella patients, anti-diarrheal drugs like loperamide are given

Bacillary dysentery

What is an example of a self-limiting disease

60S ribosomal subunit of the intestinal epithelial cell, affecting translation

What does the Shiga toxin specifically target?

Gram stain, Culture of stool sample on MAC or EMB, HE, XLD, K/A on TSIA, no gas or H2S

Diagnostics: Shigella dysenteriae

K/A

What is the expected result for TSIA of Shigella dysenteriae?

5-7 days

Shigellosis or Dysentery is a self-limiting disease, meaning that the diarrhea naturally passes after how many days?

Xylose Lysine Deoxycholate Agar

what does XLD stand for?

Salmonella, Shigella (cream colored colonies)

XLD agar is a differential media for what 2 species?

Cream colored colonies

What is the appearance of Shigella dysenteriae colonies on XLD?

Black colored colonies

What is the appearance of Salmonella colonies on XLD?

Bacillus-shaped, Motile

Morphology: Salmonella

Commensal (to animals) and pathogenic (to humans)

What kind of bacteria is Salmonella in reference to its interaction with host?

Via contaminated water and food or animal products

Transmission: Salmonella

Snakes, Turtles, Chicken

What are animals that serve as commensals of Salmonella?

Capsule (Vi antigen), Motile, Siderophores

What are 3 virulence factors of Salmonella?

Vi antigen

What antigen does the Salmonella capsule contain?

Typhoid (enteric) fever, Enterocolitis, Carrier State, Sepsis

Clinical Findings: Salmonella

Rose spots on chest and abdomen

What is a key characteristic of typhoid fever?

Typhoid Fever

What disease caused by Salmonella is characterized by the following symptoms:

Fever, headache, abdominal pain, rose spots on chest and abdomen

Enterocolitis

What disease caused by Salmonella is characterized by the following symptoms?

Nausea, headache, vomiting, watery diarrhea (some may contain mucous or blood), abdominal cramping, fever

Mucus or blood

What can be expected in diarrheal samples of patients with enterocolitis caused by salmonella?

TRUE

T/F: Salmonella can cause systemic infections

FALSE

T/F: Salmonella does not cause systemic infections

S. typhi, S. paratyphi

What 2 species of Salmonella are considered as typhoidal?

S. typhimurium, S. enteritidis

What 2 species of Salmonella are considered as non-typhoidal?

Facultative intracellular bacteria

Since Salmonella can survive within macrophages and neutrophils, what are they called?

Ciprofloxacin / ceftriaxone

Treatment: Typhoid Fever (S. typhi)

Fluid and electrolyte replacement

Treatment: Enterocolitis (S. typhimurium)

People without spleen

What people are more prone to typhoid infection because they cannot produce macrophages and neutrophils?

Lymph nodes can engulf and protect Salmonella, allowing them to travel towards multiple organ systems

How can Salmonella infections become systemic?

Lower right, Appendicitis

Abdominal pain caused by typhoid fever is found in what region? What does it resemble?

Enterocolitis

Most common clinical manifestation of S. typhimurium (non-typhoidal)

Gallbladder

In what organ can Salmonella reside making the host a carrier?

Gram stain; Blood, stool, or urine culture on MAC or EMB, HE, XLD; K/A, gas and H2S on TSIA

Diagnostics: Salmonella

TRUE

T/F: Antibiotics for Enterocolitis do not kill Salmonella, but may shorten symptom duration

FALSE

T/F: Antibiotics for Enterocolitis can kill Salmonella

Hektoen Enteric Agar

What does HE agar mean?

Capsule, Non-motile

Virulence Factors: Klebsiella spp.

Highly motile

Virulence Factors: Proteus mirabilis

Capsules, Motile

Virulence Factors: Enterobacter spp.

Motile, DNAse, lipase, gelatinase

Virulence Factors: Serratia marcescens

Motile, binds to intestinal wall, enterotoxins (similar to ST of E. coli)

Virulence Factors: Yersinia enterolitica

Klebsiella spp.

What is the organism that is the 2nd most cause of sepsis?

currant jelly sputum

What is the hallmark symptom of pneumonia caused by Klebsiella spp.?

Sepsis, Pneumonia with currant jelly sputum, UTI (from catheters), Granuloma inguinale

Clinical Findings: Klebsiella spp.

Very virulent, destroys lung tissue and produces craters, also has a characteristic currant jelly sputum

Describe the Pneumonia caused by Klebsiella spp.

K. pneumoniae, K. oxytoca

What are 2 species of Klebsiella that have clinical importance?

Granuloma inguinale

An STD that is caused by Klebsiella

Nosocomial, High mortality rate

What 2 things must be noted about Klebsiella, specifically on how it is acquired and its mortality rate

Cephalosporin, Ciprofloxacin, Azithromycin

Treatment: Klebsiella

TRUE

T/F: Antibiotic treatments are recommended for Klebsiella spp.

FALSE

T/F: Antibiotic treatments are not recommended for Klebsiella spp.

Spreaders in agar, even without moisture

What is a unique characteristic of Proteus mirabilis colonies?

Splits urea to ammonia and CO2

Why does Proteus mirabilis cause alkaline urine?

UTI with alkaline urine and stone formation, Sepsis

Clinical Findings: Proteus mirabilis

TRUE

T/F: Proteus mirabilis is a part of the normal gut flora

FALSE

T/F: Proteus mirabilis is not a part of the normal gut flora, so it is immediately a causative agent once detected

Ampicillin, TMP-SMX

Treatments: Proteus mirabilis

HAIs like pneumonia, UTI, wound and device infections

Clinical findings: Enterobacter spp.

ampC

What is a gene present in Enterobacter spp. that codes for beta-lactamase, making it multidrug resistant?

B-lactamase

What is the ampC gene resistant to?

Commonly found in environment and food, skin and gut microflora

What are the descriptions of Enterobacter spp. in terms of their occurrence?

Carbapenem

Treatment: Enterobacter spp.

TRUE

T/F: Enterobacter spp. is notable for being multi-drug resistant due to its ampC gene

FALSE

T/F: Klebsiella spp. is notable for being multi-drug resistant due to its ampC gene