Gram (-) bacilli (Enteric tract) - Sketchy Copy Flashcards by h h

Proteus mirabilis

lab tests

The god of the public restroom

gram (-) bacillus

Facultative Anaerobe

Swarming motillity when plated

urease (+) - Purple Color In tube

H₂S (+)

EMB medium - Pink, Lactose Negative

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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

Blood Agar Cold Enrichment (Not safe for Y. Pestis)

Serology

gram (-) bacillus

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

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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

Shared VF

(Y.Pestis has much more)

Yersins pets

Antiphagocytic Capsule

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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.

Exotoxins - Pla: Plasminogen Activator

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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

Catalase (+), Indole(ONPG+)

Green metallic** sheen on **EMB agar

Ferments Lactose (+) → pink on MacConkey’s agar

gram (-) bacillus

Encapsulated - K antigen + O antigen for Outer mem.

Facultative Anaerobe

oxidase, Urease and H2S (-)

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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

Fluids to help prevent dehydration and fatigue

If hemolytic uremic syndrome -> IV fluids, blood transfusions and kidney dialysis

Antibiogram to Check Resistance : Complicated Cases - Beta Lactam and Lactamase Inhibitor

Campylobacter jejuni

General and Biochemical Properties and Lab tests

Camping guy and the bears

* gram (-) Spiral/curved bacillus

Oxidase (+) and Catalase (+)

Skirrow Agar : Microaerophilic and Thermophile (prefers 42°C) with VPN- (Cant grow H.Pylori)

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)

*Complications: 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 for 3-5 days

Erythromycin in severe cases

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 - Peritrichous Flagella

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

3rd-generation cephalosporins, cefepime, carbapenems, fluoroquinolones, piperacillin/tazobactam, or aminoglycosides.

Some isolates are resistant to multiple antibiotics, susceptibility testing is essential.

(*Multi Drug Resistant Carbopenam or

Clindamycin)

Helicobacter Pylori

lab tests

The Helicopter Pilot

curved gram (-) bacillus ,Motile (Flagella)

Microaerophillic ,Catalase( +), oxidase (+)

Endoscopic Biopsy: Urease (+); can use Urease Breath Test! (urea is broken down and exhaled as CO₂ and NH₃)

ELISA from Urine/Blood Sample with Westren Blot to confirm

Helicobacter Pylori

The Helicopter Pilot

Urease is the major VF: reduces the acidity of the stomach, allowing H. Pylori to survive there.

Adhesins used to adhere to stomach

Mucinase aids the penetration into the mucous layer of the stomach

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 - Omeprazole

Amoxicillin

Macrolide: Clarithromycin

(Severe cases with +Metronidazole, if resistant - Bismuth salts)

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

VFs

The suiters of pseudo Mona

Exotoxin A: EF2- ADP-Ribosylation

Pyocyanin - ROS agaisnt other Microbes

Pyoverdin - Biofilms and Iron

Elastase - Complement Inhibition

PLC - Cell Membrane Lysis

Pseudomonas

Exotoxin A

The suiters of pseudo Mona

Only Gram Negative with Exotoxin

Ribosolation of EF2** → inhibition of protein synthesis and cell death

Pseudomonas

Treatment

The suiters of pseudo Mona

Piperacillin (penicillin)

amingoglycosides

and Fluoroquinolones

Salmonella enteritidis 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 enteritidis and Salmonella Typhi

Salmonella enteritidis ddx

The salmon dinner

Caused by eating undercooked chickens

Causes inflammatory diarrhea and gastroenteritis (Salmonelosis)

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

General and Biochemical Properties

Colonel Cholera’s Base Camp

Comma shaped gram (-) curved bacilli

Oxidase (+)

Acid labile

Halophile - “Salt Lover”

Vibrio Cholera

lab tests

Colonel Cholera’s Base Camp

TCBS agar (Thiosulfate-citrate-bile salts-sucrose agar) used to selectively grow and isolate Vibrio (Alkaline)

Slide Agglutination for O1 / O139 Antigens

Vibrio Cholera

Colonel Cholera’s Base Camp

Cholera toxin is the main virulence factor and is an AB type toxin

⬆ G_αs cAMP production by binding to and ⬆ activation of adenylate cyclase
Then it activate GS pathway → ⬆ cAMP → efflux of Cl and H₂O → Watery DIarrhea