Gram (-) bacilli (Enteric tract) Flashcards by Sydra Siddiqui

Proteus mirabilis

lab tests

The god of the public restroom

gram (-) bacillus

Facultative Anaerobe

Swarming motillity when plated

urease (+)

H₂S (+)

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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

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Proteus mirabilis

Treatment

The god of the public restroom

Sulfonamides

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Yersinia enterocolitica & pestis

lab tests

Yersins pets

gram (-) bacillus

“safety pin” staining (stains heavily on two ends)

encapsulated

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Yersinia enterocolitica

source

Yersins pets

Puppy feces

Contaminated milk products

(Similar to listeria; resistant to cold temperatures)

* Children most commonly infected

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Yersinia enterocolitica & pestis

Yersins pets

Encapsulated VF

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Yersinia enterocolitica

signs and symptoms

Yersins pets

Bloody diarrhea

Mimics appendicitis

Invasive systemic effects like fever, intestinal issues, leukocytes, abscesses, majar bowel issues.

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Yersinia pestis

source

Yersins pets

Rats or prarie dogs → fleas → humans

(Transmitted through humans as incidental host)

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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

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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.

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Yersinia pestis

Treatment

Yersins pets

Aminoglycosides with tetracycline

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Yersinia pestis

Vaccine

Yersins pets

Killed vaccine

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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)

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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

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Shigella

She Gorilla’s Circus

LPS (endotoxin) leads to inflammation, type 3 secretion.

Shiga toxin binds to the 60s subunit of ribosomes and inhibits translation.

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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)

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Shigella

Treatment

She Gorilla’s Circus

Macrolides and Fluoroquinolones

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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

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Escherichia coli

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)

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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)

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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)

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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

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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 Micro**aerophilic** **\*** **_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 **_intra_**cellulary** → 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 ****_Im_**motile** 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 ****_m_**ucous **_a_**ssociatied **_l_**ymphoid **_t_**issue** (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_** ****_Exo_**toxin A** **_Ribosolation_** of **EF**_2_**** → **_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 ****_Intra_**cellular** (**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**)

**_The salmon dinner_** Always from a **human source** **\* _Red spots_** on **_trunk_** / stomach #1 cause of **Osteomyletis** in adults with **sickle cell** **\***"**_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**, **c**_onstipation_****, **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** (**T**hiosulfate-**c**itrate-**b**ile salts-**s**ucrose 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** 1. ⬆ **G_αs cAMP** production by binding to and ⬆ activation of adenylate cyclase 2. 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**)