Gram (-) bacilli (Enteric tract) Flashcards
Proteus mirabilis
lab tests
The god of the public restroom
gram (-) bacillus
Facultative Anaerobe
Swarming motillity when plated
urease (+)
H2S (+)
Proteus mirabilis
signs and symptoms
The god of the public restroom
Stag horn calculi, kidney stones
(urease → ⬆ pH → kidney struvite stones → stag horn calculi on imaging)
Pain
UTI’s
FIshy Odor
Proteus mirabilis
Treatment
The god of the public restroom
Sulfonamides
Yersinia enterocolitica & pestis
lab tests
Yersins pets
gram (-) bacillus
“safety pin” staining (stains heavily on two ends)
encapsulated
Yersinia enterocolitica
source
Yersins pets
Puppy feces
Contaminated milk products
(Similar to listeria; resistant to cold temperatures)
* Children most commonly infected
Yersinia enterocolitica & pestis
VF
Yersins pets
Encapsulated VF
Yersinia enterocolitica
signs and symptoms
Yersins pets
Bloody diarrhea
Mimics appendicitis
Invasive systemic effects like fever, intestinal issues, leukocytes, abscesses, majar bowel issues.
Yersinia pestis
source
Yersins pets
Rats or prarie dogs → fleas → humans
(Transmitted through humans as incidental host)
Yersinia pestis
MOA
Yersins pets
Yersinia outer proteins inhibit macrophages through a type 3 secretion system → inhibits phagocytosis
Abscesses in organs or DIC from endotoxin and neurotoxin.
Also has Exotoxins
Yersinia pestis
signs and symptoms
Yersins pets
* Bubonic plague (25 million died)
Forms buboes (swollen inflammed lymph node).
The lymph nodes are swollen and tender.
Abcesses in organs or DIC.
Yersinia pestis
Treatment
Yersins pets
Aminoglycosides with tetracycline
Yersinia pestis
Vaccine
Yersins pets
Killed vaccine
Shigella
lab tests
She Gorilla’s Circus
gram (-) bacillus
Facultative Intracellular
Immotile
H2S (-)
Lactose (-)
Green colonies on hektoin agar (ddx Salmonella which grows black)
(hektoin agar is yellow to salmon color if H2S or Lactose is present with the bacteira, green if neither)
Shigella
MOA
She Gorilla’s Circus
- Acid Stable (needs fewer organisms to cause infection).
- Shigella uses M cells in peyers patches to phagocytose them → then escape the phagolysosome prior to destruction → Shigella uses the host cells actin cytoskeleton to create a tail → propels itself to new cells.
- Damages tissue and releases cytokines → inflame tissue → bloody diarrhea
Shigella
VF
She Gorilla’s Circus
LPS (endotoxin) leads to inflammation, type 3 secretion.
Shiga toxin binds to the 60s subunit of ribosomes and inhibits translation.
Shigella
Signs and symptoms
She Gorilla’s Circus
Shigella Dyssentaria
gastroenteritis (inflammatory**) → **watery diarrhea → bloody diarrhea (with leukocytes)
Leads to hemolytic uremic syndrome (HUS; but more common in E. coli) in younger children (most commonly under 10 y/o)
Pro-germinal diarrhea followed with acute renal failure (glomerular damage) → Shistocytes (fragmented RBC’s)
Shigella
Treatment
She Gorilla’s Circus
Macrolides and Fluoroquinolones
Escherichia coli
lab tests
E. Cola’s soda fountain
gram (-) bacillus
Facultative Anaerobe
oxidase (-)
catalase (+)
Green metallic** sheen on **EMB agar
Ferments Lactose (+) → pink on MacConkey’s agar
Encapsulated
Escherichia coli
VF
E. Cola’s soda fountain
- Main VF are Capsular K antigen and Flagellar H antigens.
* causes neonatal meningitis only if has the K antigen
- E. coli is leading cause of gram (-) sepsis by LPS endotoxin in outer cell membrane
- Fimbriae lead to UTI’s (#1 cause of UTI’s)
Escherichia coli
Major pathotypes of E. coli
E. Cola’s soda fountain
* Enterohemorrhagic E. coli (EHEC)
* Enterotoxigenic E. coli (ETEC)
Enteropathogenic E. coli (EPEC)
Enteroinvasive E. coli (EIEC)
Enteroaggregative E. coli (EAEC)
Adherent-Invasive E. coli (AIEC)
Escherichia coli
Enterohemorrhagic E. coli (EHEC)
E. Cola’s soda fountain
Severe Hemorrhagic Colitis caused by strain 0157:H7.
Common cause is undercooked meat.
Causes bloody diarrhea with little to no fever but mucosal inflammation or invasion..
EHEC is the only E. Coli that does not ferment sorbital.
Shiga-like Toxin inhibits ribosomes at the 60s position → can cause hemolytic uretic syndrome (HUS)
Escherichia coli
Shiga-like Toxin
E. Cola’s soda fountain
Shiga-like Toxin is from the Enterohemorrhagic (EHEC) strain of E. coli
Shiga-like Toxin inhibits ribosomes at the 60s position → can cause hemolytic uretic syndrome (HUS)
Shiga-like Toxin damages endothelial cells of capillaries in the glomerulus → platlets adhere to damaged endothelial cells → ⬇ platelet count → causing thrombocytopenia → platelet clumps hemolysis RBC’s
Escherichia coli
Enterotoxigenic E. coli (ETEC)
E. Cola’s soda fountain
“Traveler’s Diarrhea”
Heat Labile toxin → produces cAMP (symp effects)
Heat Stable toxin → produces cGMP (p.s. effects)
Watery DIarrhea
Escherichia coli
Treatment
E. Cola’s soda fountain
TMP/SMX or fluoroquinolones
Campylobacter jejuni
lab tests
Camping guy and the bears
* gram (-) Spiral/curved bacillus
Microaerophilic
* Thermophile (prefers 42°C)
oxidase (+)
Campy medium or Skirrow Agar (Skirrow agar is selective for Campylobacter)
Campylobacter jejuni
Source
Camping guy and the bears
Main reservoir is intestinal tract of poultry.
Transmitted by fecal oral, contaminated water, or ingestion of raw milk.
Campylobacter jejuni
MOA
Camping guy and the bears
Bacteria colonize intestinal mucosa and attach to epithelial cells → replicate intracellulary → causing acute PMN response, edema of the mucosa, and ulcerations.
Campylobacter jejuni
Signs and symptoms
Camping guy and the bears
Bloody stools and diarrhea
Bacteremia (INVASIVE)
Reactive arthritis (Reiter syndrome)
* Ascending paralysis (Guillen barre syndrome)
Acute enteritis
Campylobacter jejuni
Guillen barre syndrome
Camping guy and the bears; (guy and bears = Guillen Barre!)
Campylobacter jejuni can cause Guillen barre syndrome.
Autoimmune response damages myelin** of **peripheral nerves leading to ascending paralysis
(starts at the feet then ascends!)
Campylobacter jejuni
Treatment
Camping guy and the bears
Supportive care
Klebsiella, Enterobacter, Serratia
lab tests
(common to all three)
Hospital room scene
gram (-) bacilli
Ferments Lactose → turns pink on MacConkeys
Klebsiella, Enterobacter, Serratia
Enterobacter ddx
Shared traits
gram (-) bacilli
Ferments Lactose → turns pink on MacConkeys
Hospital room scene
Very motile
Klebsiella, Enterobacter, Serratia
Serratia ddx
Shared traits
gram (-) bacilli
Ferments Lactose → turns pink on MacConkeys
Hospital room scene
Very motile
Red pigment when cultured
(like a pink ring around shower or bright red)
Catalase (+)
Klebsiella, Enterobacter, Serratia
Klebsiella ddx
Shared traits
gram (-) bacilli
Ferments Lactose → turns pink on MacConkeys
Hospital room scene
* 3 A’s!!! (Alcoholics, Abscesses, Aspiration)
* sputum that is red color
Klebsiella is Immotile
Urease (+)
Polysaccharide capsule
Cavatary “TB like” lesions
Klebsiella, Enterobacter, Serratia
Treatment
Hospital room scene
Multi Drug Resistant Carbopenam
or
Clindamycin
Helicobacter Pylori
lab tests
The Helicopter Pilot
curved gram (-) bacillus
All curved rods are oxidase (+)
Urease (+); can use urease breath test! (urea is broken down and exhaled as CO2 and NH3)
Motile (Flagella)
Helicobacter Pylori
VF
The Helicopter Pilot
Urease (+); can use urease breath test!
Urease is the major VF!
Urease reduces the acidity of the stomach, allowing H. Pylori to survive there.
Helicobacter Pylori
signs and symptoms
The Helicopter Pilot
Transmitted Fecal Oral or Orally.
Causes 95% of all duodenal ulcers.
Chronic infection → ⬆ acid infection → risk of developing gastric adenocarcinoma.
Can develop lymphoma of mucous associatied lymphoid tissue (MALT).
Helicobacter Pylori
Treatment
The Helicopter Pilot
Proton pump inhibitors
Amoxicillin
Macrolide - Clarithromycin
Pseudomonas
lab tests
The suiters of pseudo Mona
gram (-) bacillus
obligate Aerobe
oxidase (+)
catalase (+)
Blue green pigment when plated (from Pyocyanin and pyoverdin, may even turn wounds blue)
Encapsulated
Pseudomonas
signs and symptoms
The suiters of pseudo Mona
* Thrives in aquatic environments (HOT TUB FOLLICULITIS)
- ⬆ risk if pt has Chronic Granulomatous Disease
- Fruity grape like odor
- May turn wounds blue (from Pyocyanin and pyoverdin)
- Most common gram (-) Nosocomial Pneumonia
- Osteomyelitis in IV drug users and diabetics
- UTI’s (catheters!)
- Burn patients are especially susceptile
- Ecthyma gangrenosum
- Otitis Externa (Swimmers ear)
Pseudomonas
Respiratory failure in who?
The suiters of pseudo Mona
Respiratory failure in CF patients.
Most common gram (-) Nosocomial Pneumonia.
(CL- channels dysfunctional in CF)
Pseudomonas
MOA
The suiters of pseudo Mona
Exotoxin A
Ribosolation of EF2** → inhibition of protein synthesis and cell death
Pseudomonas
Treatment
The suiters of pseudo Mona
Piperacillin (penicillin)
amingoglycosides
and Fluoroquinolones
Salmonella enterica and Salmonella typhi
lab tests
The salmon dinner
gram (-) bacillus
Faculatative Intracellular (macrophages → colon)
motile
H2S (+) → Black on hektoen agar
Capsulated (citrate use turns indicator blue due to alk pH)
Acid labile (need high doses to cause infection)
Indole (-) due to lack of tryptophanase
Salmonella enterica and Salmonella Typhi
Salmonella enterica ddx
The salmon dinner
Caused by eating undercooked chickens
Causes inflammatory diarrhea and gastroenteritis
Contains type 3 secretion system → detects eukaryotic cells that will ⬆ infectivity
Salmonella enterica and Salmonella typhi
Salmonella typhi ddx
(Typhoid fever)
1 cause of Osteomyletis in adults with sickle cell
The salmon dinner
Always from a human source
* Red spots on trunk / stomach
*“pea soup” diarrhea
3 phases (multiply, bactereremia, 2nd bacteremia)
Salmonella enterica and Salmonella typhi
Salmonella typhi phases
(Typhoid fever)
The salmon dinner
3 phases (multiply, bactereremia, 2nd bacteremia)
1) Bacteria multiply. When enough are in the intestines → lethargy, dull frontal headaches, constipation**, rise in body temp
2) Bacteremia → fever, severely ill with a dull expressionless look, rose spots develop mainly on the trunk
3) Second bacteremia from reinfection of biliary tract → pus in stools, bleeding in payers patches, Ileum necrosis
Salmonella enterica and Salmonella typhi
Treatment
The salmon dinner
Many resistances
Do not use antidiarrheal
Salmonella Septicemia: Agressive Chloramphenicol, amp, Amox, or TMP/SMX for 10 days
Flouroquinalones (Cipro/levo)
Ceftriaxone for Invasive and Bloody
Vibrio Cholera
lab tests
Colonel Cholera’s Base Camp
Comma shaped gram (-) curved bacilli
Oxidase (+)
TCBS agar (Thiosulfate-citrate-bile salts-sucrose agar) used to selectively grow and isolate Vibrio
Acid labile (need high doses to cause infection)
Vibrio Cholera
VF
Colonel Cholera’s Base Camp
Cholera toxin is the main virulence factor and is an AB type toxin
- ⬆ Gαs cAMP production by binding to and ⬆ activation of adenylate cyclase
- Then it activate GS pathway → ⬆ cAMP → efflux of Cl and H2O → Watery DIarrhea
Vibrio Cholera
MOA
Colonel Cholera’s Base Camp
Cholera is transmitted fecal-oral due to poor sanitation** allowing it to get into **food (not an invasive infection).
Cholera attaches to the mucosa by fimbriae attaching to the ganglioside receptors in the intestinal wall.
Vibrio Cholera
signs and symptoms
Colonel Cholera’s Base Camp
Profuse watery diarrhea
“Rice Water” stool
Vibrio Cholera
Treatment
Colonel Cholera’s Base Camp
Oral rehydration with electrolytes
Vibrio vulnificus and paraliticus
ddx
Colonel Cholera’s Base Camp
contaminates seafood, especially oysters
Vibrio V. → causes Acute Gastroenteritis
Vibrio P. → causes fulminating septicemia → death
(marked edema and necrosis)
