SEVERE VOMITING AND WATERY DIARRHEA

Case Files: Microbiology

Camille ReneeSaint James School of Medicine

CCBS3 2061 STVSource: espemed.com.mx

CASE 23

A 35-year-old woman presents to the emergency room

with a 2-day history of severe diarrhea (approx. 1

L/hr) and vomiting after eating shrimp that seemed

undercooked. Her symptoms started abruptly, with

watery diarrhea followed by vomiting. Her skin is

dry and tents when lightly pinched. A complete

blood count shows an elevated white blood cell

count and an elevated hematocrit. A metabolic panel

shows hypokalemia and low serum bicarbonate.

You assess this patient to be in hypovolemic shock

and metabolic acidosis, and institute appropriate

therapy. Source: Case Files:

Microbiology

CHIEF COMPLAINT

Symptoms

Severe Watery Diarrhea

Profuse Vomiting

Signs

Skin ‘tenting’

Metabolic Acidosis

Hypokalemia

Increased WBC count

Hypovolemic ShockSource: paramedicine.comSource: Case Files: Microbiology

SKIN TENTING INDICATES DEHYDRATION

Skin tenting occurs because of a loss of

elasticity

VOMITING & DIARRHEA DDX

1) E. coli infection

2) Viral

Gastroenteritis i.e.

Rotavirus, Norovirus

3) Aeromonas

4) Vibrio

parahaemolyticus

5) Vibrio choleraeSource: margotbworldnews.com Source:

emedicine.com

1ST DDX: ESCHERICHIA COLI

Source: cdn.phys.org

Gram Negative

bacilli

Causes:

Shiga-like dysentery

Traveler’s diarrhea

Hemolytic uremic

syndrome

Responsible for up

to 45% of

internationalSource: skinsight.comSource: emedicine.com

2ND DDX: VIRAL GASTROENTERITIS

Source: tabletsmanual.com

Sporadic - Mostly

caused by rotavirus in

infants

Acute

gastroenteritis of

adults – mostly

caused by

norovirus

Fecal-oral

transmissionSource: emedicine.com

3RD DDX: VIBRIO SPECIES

Gram Negative

comma-shaped bacilli

Single Polar Flagellum

Serotypes O1 (El Tor)

and O139 (Bengal)

Consumption of

contaminated seafood i.e. shellfish, plankton

Grows in Alkaline

MediaSource: http://upload.wikimedia.org/Source: Case Files:

Microbiology

4TH DDX: AEROMONAS

Gram negative rod

Cholera-like or

dysenteric

gastroenteritis

Consumption of

contaminated

seafood

Skin infections are

common Source: medical-labs.netSource: Santhosh, SJSM Source: oscarfish.com

DDX: PROCESS OF ELIMINATION

LABORATORY INVESTIGATION

Source: judyancheta.files.wordpress.com

SELECTING THE CAUSATIVE ORGANISM

Vibrio cholerae

vs.

Vibrio

parahaemolyticus

or Vibrio

vulnificus

Vibrio

vs.

Aeromonas

DDX: TABLE OF CHARACTERISTICS

VIBRIO SPECIES CAN BE O129 RESISTANT!

O129 (2,4-diamino-6,7-diisopropylpteridine)

differential disc is Vibriostatic

Authors: Hofer E1, Reis EM, Quintaes BR,

Rodrigues DP, Feitosa IS, Angelo MR,

Ribeiro LH.

O1 (El Tor) and O22 serogroups were isolated from patients with enteritis in Ceará, Brazil during 1991-1993

2/7,058 V. cholerae Samples Were Resistant To O129

Additionally, these O129-resistant strains of V. cholerae O1 and O22 Were ALSO Resistant To Trimethoprim/ Sulfamethoxazole

DX: VIBRIO CHOLERAE

Gram Negative curved bacilli

with Single Polar Flagellum

IP: 1-3 days

Fecal-oral transmission

Serotypes O1 (El Tor) and

O139 (Bengal) are

Responsible for Epidemic

Disease

Consumption of

contaminated seafood

Grows in Alkaline MediaSource: cholera1.wikispaces.comSource: Case Files:

Microbiology

MOST COMMON MODES OF TRANSMISSION

Contaminated

Water

Ingestion of Raw

Shellfish

Flooding in

Underdeveloped

Countries

Poor Hygiene

Source: zipheal.com Source: blogcdn.comSource: Case Files-

Microbiology

THE MECHANISM OF CHOLERA TOXIN (CTX)

Bacteria attach to upper intestine

via pili and subsequently colonize

Cholera enterotoxin

1 A subunit

5 B subunits

B subunits bind to a GM1 ganglioside receptor

on the mucosal cell to allow entry of the A subunit

A subunit Overactivates Adenylate Cyclase (Gs

protein)

Hypersecretion of Water, Chloride and other

Electrolytes into the intestinal lumenSource: Microsoft OfficeSource: Case Files:

Microbiology

Source: emedicine.com

Source: Lippincott’s

DIAGNOSTIC TESTS

Clinical diagnosis

Stool sample

Cary Blair media

TCBS agar (yellow

colonies)

Hanging drop test

Darting motility

Alkaline peptone

water (enrichment

media)

Crystal VC® dipstick

rapid test

Source: amsrapidtest.comSource: www.cdc.govSource: microrao.com

DIAGNOSTIC TESTS

Specific anti-

serum can be

used in

immobilization

tests i.e.

cessation of

motility of the

organism

Electron

microscopy

Source: thumbs.dreamstime.comSource: emedicine.com

SUPPORTIVE MANAGEMENT OF CHOLERA

Oral or Intravenous

Rehydration (1st line

therapy)

Ringer’s Lactate

Solution (50-100

mL/kg/hr)

Oral Rehydration Salts

(ORS)

It should take

approximately 4 hours

to Return the Patient to

Normal Hydration StatusSource: c1.staticflickr.com Source: tspwiki.com Source: emedicine.com

Isotonic,

bicarbona

te-

containin

g fluids

are key!

SECOND LINE THERAPY

Oral Antibiotics (2nd

Line Therapy)

Doxycycline(preferred)

Tetracycline

Azithromycin

Erythromycin Trimethoprim/Sulfamethoxaz

ole

Ciprofloxacin

Ampicillin

Norfloxacin

Source: bipolarbrain.comSource: emedicine.com

VIBRIO SPECIES CAN BE O129 RESISTANT!

O129 (2,4-diamino-6,7-diisopropylpteridine) differential disc is Vibriostatic

Authours Hofer E1, Reis EM, Quintaes BR, Rodrigues DP, Feitosa IS, Angelo MR, Ribeiro LH.

O1 (El Tor) and O22 serogroups were isolated from patients with enteritis in Ceará, Brazil during 1991-1993

2/7,058 V. cholerae Samples Were Resistant To O129

Additionally, these O129-resistant strains of V. cholerae O1 and O22 Were ALSO Resistant To Trimethoprim/ Sulfamethoxazole

REHYDRATION IS LIFE SAVING

Rehydration Usually

Results in Patient Recovery

If Left Untreated, complications include:

Hypoglycemia: patient becomes too ill to eat

Hypokalemia: abundant loss of electrolytes

Acute Tubular Necrosis or Renal Failure:

kidney malfunction associated with

hypovolemic shock

Death from dehydration Source: . globalparent.unicef.ieSource: Mayoclinic.org

OVERALL TREATMENT PLAN

5 Steps

WHEN TO SUSPECT CHOLERA

According to the World Health

Organization, a case of cholera is

suspected when:

Area with disease Not known to be

present

A patient aged 5 years or older develops

Severe Dehydration or dies from Acute

Watery Diarrhea

Area With Noted Cholera epidemic

A patient aged 5 years or older develops

Acute Watery Diarrhea, With or Without

Source: b.3cdn.netSource: who.int

MORTALITY

Access to Intravenous

Therapy Determines

Cholera’s Rate of Mortality

Before IV therapy, death caused

by cholera was Greater Than

50%; it is now <1% with

appropriate therapy

Mortality rate is still the Highest

in Africa due to the lack of

equipment in some countries Source: . www.medindia.netSource: emedicine.com Source: Toronto Notes

REDUCE THE INCIDENCE OF CHOLERA

Prevent cholera

transmission by:

Engaging in

appropriate

hygienic

practices

Drinking

chlorinated or

boiled water

Ensuring

thorough cooking

Source: www.getreadyforflu.org Source: filteredwatertap.com Source: Case Files:

Microbiology

GASTRIC ACIDITY FIGHTS CHOLERA

Cholera bacilli usually

Cannot Survive in Acidic

Environments

Patients with Achlorhydria

(Low Levels of Stomach

Acid) from taking

antacids, H2 blockers, or

proton pump inhibitors

are at a Greater Risk of

Developing CholeraSource: . cdn.return2health.net Source: Mayoclinic.org

PASSIVE IMMUNITY

Infants Who

Derive Passive

Immunity from

nursing mothers

who have

previously had

cholera are Not

Susceptible to

CholeraSource: . foodnavigator-asia.comSource: Mayoclinic.org

VACCINES FOR TRAVELERS

Vaccines are available in Select Countries

1. Parenteral

Approximately 50% efficacy

2. Killed whole cell V. cholerae with

recombinant B-subunit of CTX (Dukoral)

Approximately 50% efficacy after 3 years

3. Live attenuated CVD 103-HgR

>90% efficacy after 1 week

Source: . static.ddmcdn.comSource: slideshare.net Source: Toronto Notes

MULTIPLE CHOICE QUESTIONS

QUESTION 1

Which of the following statements is true of cholera enterotoxin?

a) Produces its effect by stimulating adenylate cyclase

activity in mucosal cells

b) Causes destruction of the

intestinal mucosa allowing for

invasive infection

c) Causes a net efflux of ions and

water from tissue into the lumen

of the large intestine

d) Is a protein with a molecular weight of

approximately 284,000 daltonsSource: sharinginhealth.caSource: Case Files:

Microbiology

ANSWER

A. Vibrio cholerae consists of an

enterotoxin A subunit that increases

adenylate cyclase activity, causing

hypersecretion of chloride and bicarbonate.

This prevents sodium and chloride to be

absorbed into cells, resulting in a massive

secretion of fluid into the intestinal lumen.

Source: Case Files:

Microbiology

QUESTION 2

What differential medium is used to distinguish Aeromonas spp. from Vibriospp.?

a) Xylose lysine desoxyscholate (XLD) agar

b) O129 differential disc

c) Hektoen enteric agar

d) Buffered charcoal yeast extract agar

e) Mannitol salt agar

ANSWER

B. To distinguish between Vibrio and

aeromonas, an O129 differential disc (2,4-

diamino-6,7-di-isopropylpteridine phosphate)

susceptibility is done:

Vibrio = “S” (susceptible)

Aeromonas =“R” (resistant)

Source: Santhosh, SJSM

QUESTION 3

What is the first-line treatment for cholera?

a) Administering the antimicrobial agent

doxycycline

b) Provide vaccination to stimulate the

patient’s immune system

c) Volume replacement with isotonic

bicarbonate fluid (i.e. Ringer’s lactate

solution)

d) Administering the antimicrobial agent

quinolone

ANSWER

C. The treatment of cholera involves

volume replacement with isotonic,

bicarbonate-containing fluids, either using

oral rehydration solutions in mild to

moderate dehydration or IV fluids, such as

Ringers lactate solution, in the profoundly

dehydrated or those unable to tolerate oral

intake.

Source: Case Files:

Microbiology

QUESTION 4

Which of the following culture plates may

be used to isolate Vibrio species, based

on its requirement of salt for growth?

a) Thayer-Martin medium

b) MacConkey agar

c) Blood agar

d) TCBS agar

Source: . c1.staticflickr.com

ANSWER

D. Thiosulfate-citrate-bile salts-sucrose

(TCBS) agar is the culture medium used

to selectively isolate Vibrio species. Blood

agar detects hemolysis, Thayer-Martin

medium isolates Neisseriae, and MacConkey

agar detects lactose-fermenting organisms.

Source: Santhosh, SJSM

QUESTION 5

An individual experiences watery diarrhea and fever

after eating raw shellfish in San Francisco. When

cultured onto a selective medium called TCBS, it

yielded green colored colonies.

Which among the following is the organism that is

responsible for the above manifestations and

symptoms?

a) Salmonella typhi

b) Vibrio parahaemolyticus

c) Vibrio cholerae

d) Clostridium difficile

e) Campylobacter jejuni Source: vibrio-cholerae.org/Source: Santhosh, SJSM

ANSWER

B. Like V. cholerae, V.

parahaemolyticus causes acute

gastroenteritis following ingestion of

contaminated seafood such as raw fish or

shellfish. The patient will develop vomiting,

abdominal cramps, fever, and diarrhea. It is

diagnosable on TCBS agar as green

colonies.

Source: Case Files:

Microbiology

GOOD JOB!

Source: . slvrdlphn.com

ACKNOWLEDGEMENTS

Professors

Dr. Mohamed Shata

Dr. Rana Zeine

Dr. Anwural Siddiqui

Dr. Fatima Marankan

Dr. Daphne Santhosh

REFERENCES

1. Liberman, M.A. & Ricer, E. (2010). Lippincott’s illustrated Q&A review of biochemistry. Wolters

Kluwer: Hong Kong

2. Kumar, V., Abbas, A.K., & Fausto, N. (2005). Robbins and cotran pathologic basis of disease,

7th ed. Elsevier Saunders: Philadelphia

3. Toy, E.C., Uthman, M.O., Uthman, E., & Brown, E.J. (2008). Case files: microbiology. United

States of America: McGraw-Hill Companies, Inc.

4. Cholera diagnosis. (2014). Retrieved March 3, 2015 from

http://www.cdc.gov/cholera/diagnosis.html

5. Cholera. (2014). Retrieved March 6, 2015 from http://www.mayoclinic.org/diseases-

conditions/cholera/basics/definition/con-20031469

6. Le, T., Bhushan, V., & Sochat, M. (2014). First aid for the usmle step 1. McGraw-Hill: Chicago

7. Cholera. (2015). Retrieved March 9, 2015 from

http://emedicine.medscape.com/article/962643-overview

Questions?

Source: . pixshark.com