Vibrio cholerae: Difference between revisions
From IDWiki
Vibrio cholerae
m (Aidan moved page Vibrio to Vibrio cholerae) |
(→) |
||
(6 intermediate revisions by the same user not shown) | |||
Line 1: | Line 1: | ||
+ | ==Background== |
||
− | = Vibrio cholerae = |
||
− | * |
+ | *Causes '''cholera''', a severe diarrheal illness that is transmitted with the fecal-oral route (food or water), and specifically associated with improper sanitation |
− | == |
+ | ===Microbiology=== |
− | * |
+ | *Curved, motile [[Stain::Gram-negative]] [[Shape::bacillus]] within the class [[Class::Gammaproteobacteria]], family [[Family::Vibrionaceae]], and genus [[Genus::Vibrio]] |
+ | *Oxidase [[Oxidase::positive]] and facultatively anaerobic |
||
− | * Serogroups O1 and O139 cause epidemic cholera, others cause mild gastroenteritis |
||
+ | *Serotypes differ in O-specific polysaccharide (OSP) chains of lipopolysaccharide (LPS), and are grouped into more than 200 serogroups |
||
+ | **Serogroups O1 and O139 cause epidemic cholera, while other serogroups cause mild gastroenteritis |
||
+ | **Serogroup O1 is divided into serotypes Inaba and Ogawa |
||
+ | **El Tor is a specific biotype of serotype O1 |
||
+ | *Halophylic, can grow in salt water with organic material |
||
+ | ===Pathophysiology=== |
||
− | == Pathogenesis == |
||
+ | *Ingestion of contaminated water leads to small intestine colonization mediated by TCP (toxin coregulated pili) |
||
− | * Can grow in salt water with organic material |
||
+ | *''Vibrio'' is non-invasive but rather causes toxin-mediated disease |
||
− | * Human are only known hosts |
||
+ | *VP1 pathogenic island is associated with pandemic strains of cholera and confers severity |
||
− | * Ingestion of contaminated water leads to small intestine colonization mediated by TCP (toxin coregulated pili) |
||
+ | *Severe secratory diarrhea cause by the virulence factor cholera toxin (CT) |
||
− | ** ''Vibrio'' is non-invasive |
||
+ | **CT causes severe secretory diarrhea |
||
− | * Severe secratory diarrhea cause by cholera toxin (CT) |
||
+ | **CT comprises 1 A subunit and 5 B subunits |
||
− | ** CT causes severe secretory diarrhea |
||
− | ** |
+ | **It enters epithelial cells by binding of B subunit to a glycosphingolipid, GM1 |
− | ** |
+ | **Inside the cell, it increases activity of adenylyl cyclase, causing an increase in cAMP, which causes chloride ion secretion |
− | ** |
+ | **CT is encoded by ctxAB genes, which were added to TCP-positive ''V. cholera'' by a bacteriophage |
− | == |
+ | ===Epidemiology=== |
+ | *Fecal-oral transmission, with humans being only known host |
||
− | * 3-5 million people affected annually |
||
+ | **Survives in brackish water |
||
− | * 100-120,000 deaths annually, but likely underestimated |
||
+ | *3-5 million people affected annually |
||
− | * Typically in poor countries with poor sanitation |
||
+ | *100-120,000 deaths annually, but likely underestimated |
||
− | * Seven pandemics described since 1817 |
||
+ | *Typically in poor countries with poor sanitation |
||
− | ** The seventh and current pandemic started in Indonesia in 1961, and is currently still circulating |
||
+ | *Seven pandemics described since 1817 |
||
− | *** The current strain is called El Tor |
||
+ | **The seventh and current pandemic started in Indonesia in 1961, and is currently still circulating |
||
+ | **The current strain is biotype El Tor within serotype O1 |
||
− | == |
+ | ===Risk Factors=== |
− | * |
+ | *Limited access to clean water and sanitation |
− | * |
+ | *In endemic countries, those less than 4 years of age |
− | * |
+ | *In newly affected countries, everyone is at risk |
+ | ==Clinical Manifestations== |
||
− | == Presentation == |
||
− | === |
+ | ===Cholera=== |
+ | *Incubation period [[Usual incubation period::6 hours to 5 days|Usual incubation period::2 hours to 5 days]], depending on the size of the inoculum |
||
− | * 6h to 5d onset requiring very low innoculum |
||
− | * |
+ | *Profuse painless watery diarrhea with rice-water stools, up to 1 L/h when severe |
+ | *Abdominal cramping and nausea |
||
− | ** Up to 1 L/h |
||
+ | *Only rarely associated with fever, as it is non-invasive |
||
− | * Abdo cramping and nausea |
||
+ | **More likely to be hypothermic from severe dehydration |
||
− | * Only rarely associated with fever, as it is non-invasive |
||
− | ** More likely to be hypothermic from severe dehydration |
||
− | === |
+ | ===Severe Cholera (Cholera Gravis)=== |
− | * |
+ | *Severe, life threatening dehydration occurs in 10-20% |
− | ** |
+ | **Profuse diarrhea, leading to shock from profound fluid losses, and, eventually, death |
+ | **Up to 1 L of diarrhea per day, with death occurring in as little as one day |
||
− | * Signs are those of severe dehydration: |
||
+ | *Signs are those of severe dehydration: |
||
− | ** Lethargy or loss of consciousness |
||
+ | **Lethargy or loss of consciousness |
||
− | ** Sunken eyes |
||
+ | **Sunken eyes |
||
− | ** Low skin turgor |
||
+ | **Low skin turgor |
||
− | ** Low blood pressure and weak pulse |
||
+ | **Low blood pressure and weak pulse |
||
− | ** Unable to drink |
||
+ | **Unable to drink |
||
+ | *Can see significant electrolyte abnormalities due to the secretory diarrhea |
||
− | === |
+ | === Cholera Sicca === |
+ | * Fluid builds up in abdomen and can cause dehydration and death even without significant bowel movements |
||
− | * 90% of colonized patients are asymptomatic but still infectious [CITATION NEEDED] |
||
− | * Among those who are symptomatic, they can shed it for months after illness (though most stop 2-3 days after symptom resolution) |
||
+ | ===Asymptomatic Carriage=== |
||
− | == Diagnosis == |
||
+ | *Colonized patients are asymptomatic but still infectious |
||
− | * Usually clinical diagnosis in low-resource settings |
||
+ | *Among those who are symptomatic, they can shed it for months after illness (though most stop 2-3 days after symptom resolution) |
||
− | * Stool culture |
||
− | ** Helpful for determining resistance during outbreaks, but not routinely done |
||
− | * Rapid stool tests, requiring dark field microscopy to see "shooting star" appearance of vibrios |
||
− | * Serology, sometimes |
||
− | == |
+ | == Differential Diagnosis == |
+ | * Refer to [[diarrhea in the returned traveller]] |
||
− | * Isolation |
||
− | * Rehydration is the main way to reduce mortality |
||
− | ** Mild: alert with normal exam |
||
− | *** Oral rehydration at home, guided by thirst |
||
− | *** Should be observed until they are reliably replacing their losses, then can be discharged home |
||
− | ** Moderate: alert to restless, with some abnormalities on exam to suggest dehydration |
||
− | *** Oral or IV rehydration in hospital |
||
− | *** Bolus 75 mL/kg over 3-4 hours |
||
− | *** Replace losses |
||
− | *** Observe until signs of dehydration resolves and patient peeing |
||
− | ** Severe: cholera gravis, as described above |
||
− | *** Aggressive IV rehydration in hospital |
||
− | *** Bolus >100 mL/kg as rapidly as possible until circulation is restored, then the remainder over 3 hours |
||
− | *** Replace losses |
||
− | * Replace electrolytes as needed, but laboratory assistance is not required in most cases |
||
− | * Antibiotics decrease duration and volume of diarrhea, and are indicated in cases of moderate or severe cholera |
||
− | ** Doxycycline 300 mg po once, avoided in pregnant women and children <8 years |
||
− | ** Azithromycin 1 g po once |
||
− | ** Ciprofloxcin used previously, but increasing resistance |
||
− | * Avoid antiemetics and antimotility agents |
||
− | * Consider zinc supplementation in children 10-30 mg daily x5-7 days |
||
− | * Can use a cholera cot |
||
+ | ==Diagnosis== |
||
− | === Choice of fluids === |
||
+ | *Usually clinical diagnosis in low-resource settings |
||
− | * D5/lactated Ringer's (D5LR) is the preferred IV fluid, though D5-NS can be used if D5LR is not available |
||
+ | **Essentially all patients 5 years of age and older who present with acute watery diarrhea causing severe dehydration |
||
− | ** "Dhaka solution" has more potassium, bicarbonate, and glucose, and is optimal |
||
+ | *Stool culture |
||
− | * NS can be used for circulatory support |
||
+ | **Helpful for determining resistance during outbreaks, but not routinely done |
||
− | * Oral rehydration solutions (ORS) have salt and glucose |
||
+ | *Rapid stool tests, requiring dark field microscopy to see "shooting star" appearance of vibrios |
||
− | ** In an emergency, can add 1/2 tsp salt with 6 tsp sugar in 1 L of clean water |
||
+ | *Serology, sometimes, with a sensitivity and specificity anywhere from 60 and 100% |
||
+ | *PCR also exists |
||
− | == |
+ | ==Management== |
+ | *Isolation |
||
− | * Dukoral and Shanchol are both killed ''Vibrio'' vaccines |
||
+ | *Rehydration is the main way to reduce mortality |
||
− | * Immunity lasts 6 months to a few years, not approved in children |
||
+ | **Mild: alert with normal exam |
||
− | ** Boosters every 2 years |
||
+ | ***Oral rehydration at home, guided by thirst |
||
− | * Both vaccines are well-tolerated but only 60-80% effective |
||
+ | ***Should be observed until they are reliably replacing their losses, then can be discharged home |
||
− | * During outbreaks, they have about 80% effectiveness |
||
+ | **Moderate: alert to restless, with some abnormalities on exam to suggest dehydration |
||
+ | ***Oral or IV rehydration in hospital |
||
+ | ***Bolus 75 mL/kg over 3-4 hours |
||
+ | ***Replace losses |
||
+ | ***Observe until signs of dehydration resolves and patient peeing |
||
+ | **Severe: cholera gravis, as described above |
||
+ | ***Aggressive IV rehydration in hospital |
||
+ | ***Bolus >100 mL/kg as rapidly as possible until circulation is restored, then the remainder over 3 hours |
||
+ | ***Replace losses |
||
+ | *Replace electrolytes as needed, but laboratory assistance is not required in most cases |
||
+ | *Antibiotics decrease duration and volume of diarrhea, and are indicated in cases of moderate or severe cholera |
||
+ | **[[Doxycycline]] 300 mg po once, avoided in pregnant women and children <8 years |
||
+ | **[[Azithromycin]] 1 g po once |
||
+ | **[[Ciprofloxacin]] used previously, but increasing resistance |
||
+ | *Avoid [[antiemetics]] and antimotility agents |
||
+ | *Consider [[zinc]] supplementation in children 10-30 mg daily x5-7 days |
||
+ | *Can use a cholera cot |
||
+ | ===Rehydration Fluids=== |
||
− | == Prognosis == |
||
+ | *D5/lactated Ringer's (D5LR) is the preferred IV fluid, though D5-NS can be used if D5LR is not available |
||
− | * Depends on context (rich vs poor) |
||
+ | **"Dhaka solution" has more potassium, bicarbonate, and glucose, and is optimal |
||
+ | *NS can be used for circulatory support |
||
+ | *[[Oral rehydration solution]] (ORS) has salt and glucose |
||
+ | **In an emergency, can add 1/2 tsp salt with 6 tsp sugar in 1 L of clean water |
||
+ | ==Prevention== |
||
− | == Further Reading == |
||
+ | *Improved water hygiene and sanitation is the backbone of long-term prevention, but is expensive and slow to set up |
||
− | * [http://www.cotsprogram.com/ Cholera Outbreak Training and Shigellosis (COTS) Program]: information and tools for managing cholera |
||
+ | |||
+ | ===Infection Prevention and Control=== |
||
+ | |||
+ | *Routine precautions |
||
+ | *Needs contact precaution if: |
||
+ | **Pediatric patient |
||
+ | **Incontinent |
||
+ | **Stool not contained |
||
+ | **Poor hygiene |
||
+ | **Patient is contaminating the environment |
||
+ | *Continue until 48 hours after symptoms have resolved |
||
+ | |||
+ | ===Immunization=== |
||
+ | |||
+ | *All vaccines in use are based on killed ''Vibrio cholerae'' |
||
+ | **Dukoral is killed whole-cell serotype O1, classic and El Tor biotypes, with additional recombinant cholera toxin subunit B (CtxB) |
||
+ | **Shanchol (India) is bivalent, including a number of O1 strains as well as O139, without the addition of CtxB |
||
+ | **Euvichol (South Korea) similar to Shanchol |
||
+ | **mORCVAX (Vietnam) is similar to Shanchol, but only available locally in Vietnam |
||
+ | *For children, Dukoral is approved for people aged 2 years and older while the others are for ages 1 and older |
||
+ | *Dukoral needs boosters every 2 years (or every 6 months for children younger than 5 years) |
||
+ | *All vaccines are well-tolerated but only 60-80% effective within 6 months (Dukoral) to 5 years (Shanchol and Euvichol) |
||
+ | **During outbreaks, they have about 80% effectiveness and vaccine rates of at least 50% are needed to interrupt transmission |
||
+ | |||
+ | ==Further Reading== |
||
+ | |||
+ | *[http://www.cotsprogram.com/ Cholera Outbreak Training and Shigellosis (COTS) Program]: information and tools for managing cholera |
||
+ | |||
+ | {{DISPLAYTITLE:''Vibrio cholerae''}} |
||
+ | [[Category:Gram-negative bacilli]] |
Latest revision as of 22:05, 5 July 2022
Background
- Causes cholera, a severe diarrheal illness that is transmitted with the fecal-oral route (food or water), and specifically associated with improper sanitation
Microbiology
- Curved, motile Gram-negative bacillus within the class Gammaproteobacteria, family Vibrionaceae, and genus Vibrio
- Oxidase positive and facultatively anaerobic
- Serotypes differ in O-specific polysaccharide (OSP) chains of lipopolysaccharide (LPS), and are grouped into more than 200 serogroups
- Serogroups O1 and O139 cause epidemic cholera, while other serogroups cause mild gastroenteritis
- Serogroup O1 is divided into serotypes Inaba and Ogawa
- El Tor is a specific biotype of serotype O1
- Halophylic, can grow in salt water with organic material
Pathophysiology
- Ingestion of contaminated water leads to small intestine colonization mediated by TCP (toxin coregulated pili)
- Vibrio is non-invasive but rather causes toxin-mediated disease
- VP1 pathogenic island is associated with pandemic strains of cholera and confers severity
- Severe secratory diarrhea cause by the virulence factor cholera toxin (CT)
- CT causes severe secretory diarrhea
- CT comprises 1 A subunit and 5 B subunits
- It enters epithelial cells by binding of B subunit to a glycosphingolipid, GM1
- Inside the cell, it increases activity of adenylyl cyclase, causing an increase in cAMP, which causes chloride ion secretion
- CT is encoded by ctxAB genes, which were added to TCP-positive V. cholera by a bacteriophage
Epidemiology
- Fecal-oral transmission, with humans being only known host
- Survives in brackish water
- 3-5 million people affected annually
- 100-120,000 deaths annually, but likely underestimated
- Typically in poor countries with poor sanitation
- Seven pandemics described since 1817
- The seventh and current pandemic started in Indonesia in 1961, and is currently still circulating
- The current strain is biotype El Tor within serotype O1
Risk Factors
- Limited access to clean water and sanitation
- In endemic countries, those less than 4 years of age
- In newly affected countries, everyone is at risk
Clinical Manifestations
Cholera
- Incubation period Usual incubation period::2 hours to 5 days, depending on the size of the inoculum
- Profuse painless watery diarrhea with rice-water stools, up to 1 L/h when severe
- Abdominal cramping and nausea
- Only rarely associated with fever, as it is non-invasive
- More likely to be hypothermic from severe dehydration
Severe Cholera (Cholera Gravis)
- Severe, life threatening dehydration occurs in 10-20%
- Profuse diarrhea, leading to shock from profound fluid losses, and, eventually, death
- Up to 1 L of diarrhea per day, with death occurring in as little as one day
- Signs are those of severe dehydration:
- Lethargy or loss of consciousness
- Sunken eyes
- Low skin turgor
- Low blood pressure and weak pulse
- Unable to drink
- Can see significant electrolyte abnormalities due to the secretory diarrhea
Cholera Sicca
- Fluid builds up in abdomen and can cause dehydration and death even without significant bowel movements
Asymptomatic Carriage
- Colonized patients are asymptomatic but still infectious
- Among those who are symptomatic, they can shed it for months after illness (though most stop 2-3 days after symptom resolution)
Differential Diagnosis
- Refer to diarrhea in the returned traveller
Diagnosis
- Usually clinical diagnosis in low-resource settings
- Essentially all patients 5 years of age and older who present with acute watery diarrhea causing severe dehydration
- Stool culture
- Helpful for determining resistance during outbreaks, but not routinely done
- Rapid stool tests, requiring dark field microscopy to see "shooting star" appearance of vibrios
- Serology, sometimes, with a sensitivity and specificity anywhere from 60 and 100%
- PCR also exists
Management
- Isolation
- Rehydration is the main way to reduce mortality
- Mild: alert with normal exam
- Oral rehydration at home, guided by thirst
- Should be observed until they are reliably replacing their losses, then can be discharged home
- Moderate: alert to restless, with some abnormalities on exam to suggest dehydration
- Oral or IV rehydration in hospital
- Bolus 75 mL/kg over 3-4 hours
- Replace losses
- Observe until signs of dehydration resolves and patient peeing
- Severe: cholera gravis, as described above
- Aggressive IV rehydration in hospital
- Bolus >100 mL/kg as rapidly as possible until circulation is restored, then the remainder over 3 hours
- Replace losses
- Mild: alert with normal exam
- Replace electrolytes as needed, but laboratory assistance is not required in most cases
- Antibiotics decrease duration and volume of diarrhea, and are indicated in cases of moderate or severe cholera
- Doxycycline 300 mg po once, avoided in pregnant women and children <8 years
- Azithromycin 1 g po once
- Ciprofloxacin used previously, but increasing resistance
- Avoid antiemetics and antimotility agents
- Consider zinc supplementation in children 10-30 mg daily x5-7 days
- Can use a cholera cot
Rehydration Fluids
- D5/lactated Ringer's (D5LR) is the preferred IV fluid, though D5-NS can be used if D5LR is not available
- "Dhaka solution" has more potassium, bicarbonate, and glucose, and is optimal
- NS can be used for circulatory support
- Oral rehydration solution (ORS) has salt and glucose
- In an emergency, can add 1/2 tsp salt with 6 tsp sugar in 1 L of clean water
Prevention
- Improved water hygiene and sanitation is the backbone of long-term prevention, but is expensive and slow to set up
Infection Prevention and Control
- Routine precautions
- Needs contact precaution if:
- Pediatric patient
- Incontinent
- Stool not contained
- Poor hygiene
- Patient is contaminating the environment
- Continue until 48 hours after symptoms have resolved
Immunization
- All vaccines in use are based on killed Vibrio cholerae
- Dukoral is killed whole-cell serotype O1, classic and El Tor biotypes, with additional recombinant cholera toxin subunit B (CtxB)
- Shanchol (India) is bivalent, including a number of O1 strains as well as O139, without the addition of CtxB
- Euvichol (South Korea) similar to Shanchol
- mORCVAX (Vietnam) is similar to Shanchol, but only available locally in Vietnam
- For children, Dukoral is approved for people aged 2 years and older while the others are for ages 1 and older
- Dukoral needs boosters every 2 years (or every 6 months for children younger than 5 years)
- All vaccines are well-tolerated but only 60-80% effective within 6 months (Dukoral) to 5 years (Shanchol and Euvichol)
- During outbreaks, they have about 80% effectiveness and vaccine rates of at least 50% are needed to interrupt transmission
Further Reading
- Cholera Outbreak Training and Shigellosis (COTS) Program: information and tools for managing cholera