Vibrio, Aeromonas, Plesiomonas, and Campylobacter Overview

Vibrio species

10 species involved in human infections.

Habitat of Vibrio

Found in fresh, brackish, and salt water.

Temperature preference

Prefers warmer water environments.

Epidemic involvement

Usually associated with cyclical epidemics.

Vibrio cholerae

Causative agent of cholera disease.

Vibrio parahemolyticus

Commonly associated with seafood-related infections.

Vibrio vulnificus

Linked to severe infections from seafood.

Vibrio alginolyticus

Associated with marine environments and infections.

Isolation increase factors

Rising ocean temperatures and seafood consumption.

Risk factors for infection

Raw seafood consumption, travel, and trauma.

Gastroenteritis symptoms

Cholera-like or rice-water stools observed.

General characteristics

Facultatively anaerobic, gram-negative, small rods.

Size of Vibrio

1.4 to 2.6 µm long.

Morphology

Pleomorphic shapes, curved in Gram stain.

Biochemical tests

Catalase and oxidase positive, nitrate reduction.

Vibriostat disk

Used to differentiate Vibrio from others.

O/129 susceptibility

Separates Vibrio from Aeromonas and Plesiomonas.

String test

Identifies Vibrio by emulsifying colonies.

Halophilic nature

Most Vibrio species are salt-loving.

V. cholerae subgroups

Three major subgroups with common antigens.

Epidemic cholera serotypes

V. cholerae O1 and O139 are epidemic.

Epidemiology of cholera

Seven pandemics since 1817, last in 1975.

Cholera in the US

Last outbreak occurred 1910-1911.

Common cholera regions

Bengal region of India and Bangladesh.

Imported cholera cases

Most US cases considered imported.

Infection prevention

Quarantine measures historically used to control outbreaks.

Recreational water exposure

Increased risk of Vibrio infections.

Immunocompromised population

Higher susceptibility to Vibrio infections.

Clinical specimen isolation

Low frequency except in coastal areas.

Cholera

Bacterial infection causing severe diarrhea and dehydration.

2010 Haiti Earthquake

Natural disaster affecting 3 million people.

Artibonite River

Major drinking water source in Haiti.

Nepalese UN Peacekeepers

Stationed in Haiti during cholera outbreak.

Fecal Contamination

Primary cause of cholera outbreak in Haiti.

Cholera Symptoms

Rice-water stool and large fluid loss.

Hypovolemic Shock

Condition from severe fluid loss.

Cholera Toxin

Causes diarrhea by stimulating cAMP production.

cAMP

Cyclic adenosine monophosphate, increases fluid secretion.

Cholera Transmission

Spread through contaminated water and food.

V. cholerae O1

Most common strain causing cholera outbreaks.

V. cholerae O139

Causes cholera outbreaks in India and Bangladesh.

V. cholerae non-01

Non-toxigenic strain causing milder gastroenteritis.

V. parahaemolyticus

Bacteria causing summer diarrhea from seafood.

Serotype O3:K6

Major cause of foodborne outbreaks worldwide.

Kanagawa Phenomenon

Heat-stabile hemolysin associated with V. parahaemolyticus.

Self-limiting Diarrhea

Watery diarrhea resolving without treatment.

V. vulnificus

Lactose-positive Vibrio causing severe infections.

Septicemia

Blood infection with high mortality rate.

Specimen Collection

Collect fluids, pus, tissues for Vibrio testing.

Cary-Blair Medium

Transport medium preventing desiccation of samples.

Raw Seafood Risk

Source of V. vulnificus infections.

Electrolyte Loss

Significant loss during cholera infection.

Diarrhea Frequency

10-30 movements per day in cholera.

Dehydration Treatment

IV and oral fluids with electrolytes.

Antibiotic Resistance

Reported resistance to tetracycline and doxycycline.

Extraintestinal Infections

Wound, eye, ear infections from V. parahaemolyticus.

Marine Animal Association

V. parahaemolyticus linked to 30 species.

Vibrio Species

Bacteria primarily found in aquatic environments.

Blood Agar Plate (BAP)

Culture medium suitable for Vibrios.

MacConkey Plates

Selective agar for Gram-negative bacteria.

Lactose Negative

Characteristic of most Vibrio species except V. vulnificus.

Thiosulfate-Citrate-Bile Salts-Sucrose (TCBS)

Medium for isolating Vibrio species.

V. cholerae

Causes cholera, appears yellow on TCBS.

V. parahaemolyticus

Green on TCBS, associated with seafood.

Antimicrobial Susceptibility Testing

Evaluates bacteria's resistance to antibiotics.

Clinical and Laboratory Standards Institute (CLSI)

Sets standards for antimicrobial susceptibility testing.

Doxycycline

Commonly effective antibiotic against Vibrio species.

Ciprofloxacin

Fluoroquinolone effective against Vibrio infections.

Aeromonas

Gram-negative rods, oxidase positive, glucose fermenting.

Mesophilic Aeromonas

Optimal growth at 37°C, includes A. hydrophila.

Psychrophilic Aeromonas

Optimal growth at 22°C, includes fish pathogen.

Gastroenteritis

Infection causing diarrhea, often from contaminated water.

Acute Secretory Diarrhea

Diarrhea with watery stools, often viral or bacterial.

Cholera-like Disease

Presents with rice-water stools, similar to cholera.

Wound Infection

Infection from injuries in contaminated water.

Septicemia

Blood infection, can be caused by A. veronii.

Osteomyelitis

Bone infection, can be caused by Aeromonas.

Indole Positive

Characteristic of most clinically relevant Aeromonas species.

String Test Negative

Differentiates Aeromonas from Vibrio species.

Plesiomonas

Similar to Aeromonas, grows well in 0% NaCl.

Inositol Negative

Aeromonas does not ferment inositol.

Trimethoprim/Sulfamethoxazole

Effective against Aeromonas infections.

A. hydrophila

Commonly associated with wound infections and gastroenteritis.

A. veronii

Associated with septicemia in immunocompromised patients.

Beta Hemolysis on SBA

Characteristic of Aeromonas hydrophila on sheep blood agar.

Lactose Fermentation

Aeromonas caviae can ferment lactose on MAC.

Plesiomonas

Gram-negative rod, formerly in Vibrionaceae.

Enterobacteriaceae

Family of bacteria including Plesiomonas.

Gram-negative

Bacteria with thin peptidoglycan layer.

Oxidase positive

Indicates presence of cytochrome c oxidase.

Glucose fermenting

Can metabolize glucose without gas production.

Facultatively anaerobic

Can grow with or without oxygen.

Motile

Capable of movement, often via flagella.

Vibriostat (O/129) disks

Used to test susceptibility of Plesiomonas.

Gastroenteritis

Inflammation of stomach and intestines.

Watery diarrhea

Common symptom of Plesiomonas infection.

Dysenteric form

Severe diarrhea resembling colitis.

Inositol brilliant green bile salts (IBB)

Special media for culturing Plesiomonas.

Lactose fermenter

Ability to ferment lactose, distinguishes bacteria.

High salt tolerance

Vibrio species grow in high salt concentrations.